Linux 4.16.11

[linux/fpc-iii.git] / drivers / tty / synclink.c

// SPDX-License-Identifier: GPL-1.0+
/*
 * $Id: synclink.c,v 4.38 2005/11/07 16:30:34 paulkf Exp $
 *
 * Device driver for Microgate SyncLink ISA and PCI
 * high speed multiprotocol serial adapters.
 *
 * written by Paul Fulghum for Microgate Corporation
 * paulkf@microgate.com
 *
 * Microgate and SyncLink are trademarks of Microgate Corporation
 *
 * Derived from serial.c written by Theodore Ts'o and Linus Torvalds
 *
 * Original release 01/11/99
 *
 * This driver is primarily intended for use in synchronous
 * HDLC mode. Asynchronous mode is also provided.
 *
 * When operating in synchronous mode, each call to mgsl_write()
 * contains exactly one complete HDLC frame. Calling mgsl_put_char
 * will start assembling an HDLC frame that will not be sent until
 * mgsl_flush_chars or mgsl_write is called.
 * 
 * Synchronous receive data is reported as complete frames. To accomplish
 * this, the TTY flip buffer is bypassed (too small to hold largest
 * frame and may fragment frames) and the line discipline
 * receive entry point is called directly.
 *
 * This driver has been tested with a slightly modified ppp.c driver
 * for synchronous PPP.
 *
 * 2000/02/16
 * Added interface for syncppp.c driver (an alternate synchronous PPP
 * implementation that also supports Cisco HDLC). Each device instance
 * registers as a tty device AND a network device (if dosyncppp option
 * is set for the device). The functionality is determined by which
 * device interface is opened.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#if defined(__i386__)
#  define BREAKPOINT() asm("   int $3");
#else
#  define BREAKPOINT() { }
#endif

#define MAX_ISA_DEVICES 10
#define MAX_PCI_DEVICES 10
#define MAX_TOTAL_DEVICES 20

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/synclink.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/dma.h>
#include <linux/bitops.h>
#include <asm/types.h>
#include <linux/termios.h>
#include <linux/workqueue.h>
#include <linux/hdlc.h>
#include <linux/dma-mapping.h>

#if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINK_MODULE))
#define SYNCLINK_GENERIC_HDLC 1
#else
#define SYNCLINK_GENERIC_HDLC 0
#endif

#define GET_USER(error,value,addr) error = get_user(value,addr)
#define COPY_FROM_USER(error,dest,src,size) error = copy_from_user(dest,src,size) ? -EFAULT : 0
#define PUT_USER(error,value,addr) error = put_user(value,addr)
#define COPY_TO_USER(error,dest,src,size) error = copy_to_user(dest,src,size) ? -EFAULT : 0

#include <linux/uaccess.h>

#define RCLRVALUE 0xffff

static MGSL_PARAMS default_params = {
        MGSL_MODE_HDLC,                 /* unsigned long mode */
        0,                              /* unsigned char loopback; */
        HDLC_FLAG_UNDERRUN_ABORT15,     /* unsigned short flags; */
        HDLC_ENCODING_NRZI_SPACE,       /* unsigned char encoding; */
        0,                              /* unsigned long clock_speed; */
        0xff,                           /* unsigned char addr_filter; */
        HDLC_CRC_16_CCITT,              /* unsigned short crc_type; */
        HDLC_PREAMBLE_LENGTH_8BITS,     /* unsigned char preamble_length; */
        HDLC_PREAMBLE_PATTERN_NONE,     /* unsigned char preamble; */
        9600,                           /* unsigned long data_rate; */
        8,                              /* unsigned char data_bits; */
        1,                              /* unsigned char stop_bits; */
        ASYNC_PARITY_NONE               /* unsigned char parity; */
};

#define SHARED_MEM_ADDRESS_SIZE 0x40000
#define BUFFERLISTSIZE 4096
#define DMABUFFERSIZE 4096
#define MAXRXFRAMES 7

typedef struct _DMABUFFERENTRY
{
        u32 phys_addr;  /* 32-bit flat physical address of data buffer */
        volatile u16 count;     /* buffer size/data count */
        volatile u16 status;    /* Control/status field */
        volatile u16 rcc;       /* character count field */
        u16 reserved;   /* padding required by 16C32 */
        u32 link;       /* 32-bit flat link to next buffer entry */
        char *virt_addr;        /* virtual address of data buffer */
        u32 phys_entry; /* physical address of this buffer entry */
        dma_addr_t dma_addr;
} DMABUFFERENTRY, *DMAPBUFFERENTRY;

/* The queue of BH actions to be performed */

#define BH_RECEIVE  1
#define BH_TRANSMIT 2
#define BH_STATUS   4

#define IO_PIN_SHUTDOWN_LIMIT 100

struct  _input_signal_events {
        int     ri_up;  
        int     ri_down;
        int     dsr_up;
        int     dsr_down;
        int     dcd_up;
        int     dcd_down;
        int     cts_up;
        int     cts_down;
};

/* transmit holding buffer definitions*/
#define MAX_TX_HOLDING_BUFFERS 5
struct tx_holding_buffer {
        int     buffer_size;
        unsigned char * buffer;
};


/*
 * Device instance data structure
 */
 
struct mgsl_struct {
        int                     magic;
        struct tty_port         port;
        int                     line;
        int                     hw_version;
        
        struct mgsl_icount      icount;
        
        int                     timeout;
        int                     x_char;         /* xon/xoff character */
        u16                     read_status_mask;
        u16                     ignore_status_mask;     
        unsigned char           *xmit_buf;
        int                     xmit_head;
        int                     xmit_tail;
        int                     xmit_cnt;
        
        wait_queue_head_t       status_event_wait_q;
        wait_queue_head_t       event_wait_q;
        struct timer_list       tx_timer;       /* HDLC transmit timeout timer */
        struct mgsl_struct      *next_device;   /* device list link */
        
        spinlock_t irq_spinlock;                /* spinlock for synchronizing with ISR */
        struct work_struct task;                /* task structure for scheduling bh */

        u32 EventMask;                  /* event trigger mask */
        u32 RecordedEvents;             /* pending events */

        u32 max_frame_size;             /* as set by device config */

        u32 pending_bh;

        bool bh_running;                /* Protection from multiple */
        int isr_overflow;
        bool bh_requested;
        
        int dcd_chkcount;               /* check counts to prevent */
        int cts_chkcount;               /* too many IRQs if a signal */
        int dsr_chkcount;               /* is floating */
        int ri_chkcount;

        char *buffer_list;              /* virtual address of Rx & Tx buffer lists */
        u32 buffer_list_phys;
        dma_addr_t buffer_list_dma_addr;

        unsigned int rx_buffer_count;   /* count of total allocated Rx buffers */
        DMABUFFERENTRY *rx_buffer_list; /* list of receive buffer entries */
        unsigned int current_rx_buffer;

        int num_tx_dma_buffers;         /* number of tx dma frames required */
        int tx_dma_buffers_used;
        unsigned int tx_buffer_count;   /* count of total allocated Tx buffers */
        DMABUFFERENTRY *tx_buffer_list; /* list of transmit buffer entries */
        int start_tx_dma_buffer;        /* tx dma buffer to start tx dma operation */
        int current_tx_buffer;          /* next tx dma buffer to be loaded */
        
        unsigned char *intermediate_rxbuffer;

        int num_tx_holding_buffers;     /* number of tx holding buffer allocated */
        int get_tx_holding_index;       /* next tx holding buffer for adapter to load */
        int put_tx_holding_index;       /* next tx holding buffer to store user request */
        int tx_holding_count;           /* number of tx holding buffers waiting */
        struct tx_holding_buffer tx_holding_buffers[MAX_TX_HOLDING_BUFFERS];

        bool rx_enabled;
        bool rx_overflow;
        bool rx_rcc_underrun;

        bool tx_enabled;
        bool tx_active;
        u32 idle_mode;

        u16 cmr_value;
        u16 tcsr_value;

        char device_name[25];           /* device instance name */

        unsigned int bus_type;  /* expansion bus type (ISA,EISA,PCI) */
        unsigned char bus;              /* expansion bus number (zero based) */
        unsigned char function;         /* PCI device number */

        unsigned int io_base;           /* base I/O address of adapter */
        unsigned int io_addr_size;      /* size of the I/O address range */
        bool io_addr_requested;         /* true if I/O address requested */
        
        unsigned int irq_level;         /* interrupt level */
        unsigned long irq_flags;
        bool irq_requested;             /* true if IRQ requested */
        
        unsigned int dma_level;         /* DMA channel */
        bool dma_requested;             /* true if dma channel requested */

        u16 mbre_bit;
        u16 loopback_bits;
        u16 usc_idle_mode;

        MGSL_PARAMS params;             /* communications parameters */

        unsigned char serial_signals;   /* current serial signal states */

        bool irq_occurred;              /* for diagnostics use */
        unsigned int init_error;        /* Initialization startup error                 (DIAGS) */
        int     fDiagnosticsmode;       /* Driver in Diagnostic mode?                   (DIAGS) */

        u32 last_mem_alloc;
        unsigned char* memory_base;     /* shared memory address (PCI only) */
        u32 phys_memory_base;
        bool shared_mem_requested;

        unsigned char* lcr_base;        /* local config registers (PCI only) */
        u32 phys_lcr_base;
        u32 lcr_offset;
        bool lcr_mem_requested;

        u32 misc_ctrl_value;
        char *flag_buf;
        bool drop_rts_on_tx_done;

        bool loopmode_insert_requested;
        bool loopmode_send_done_requested;
        
        struct  _input_signal_events    input_signal_events;

        /* generic HDLC device parts */
        int netcount;
        spinlock_t netlock;

#if SYNCLINK_GENERIC_HDLC
        struct net_device *netdev;
#endif
};

#define MGSL_MAGIC 0x5401

/*
 * The size of the serial xmit buffer is 1 page, or 4096 bytes
 */
#ifndef SERIAL_XMIT_SIZE
#define SERIAL_XMIT_SIZE 4096
#endif

/*
 * These macros define the offsets used in calculating the
 * I/O address of the specified USC registers.
 */


#define DCPIN 2         /* Bit 1 of I/O address */
#define SDPIN 4         /* Bit 2 of I/O address */

#define DCAR 0          /* DMA command/address register */
#define CCAR SDPIN              /* channel command/address register */
#define DATAREG DCPIN + SDPIN   /* serial data register */
#define MSBONLY 0x41
#define LSBONLY 0x40

/*
 * These macros define the register address (ordinal number)
 * used for writing address/value pairs to the USC.
 */

#define CMR     0x02    /* Channel mode Register */
#define CCSR    0x04    /* Channel Command/status Register */
#define CCR     0x06    /* Channel Control Register */
#define PSR     0x08    /* Port status Register */
#define PCR     0x0a    /* Port Control Register */
#define TMDR    0x0c    /* Test mode Data Register */
#define TMCR    0x0e    /* Test mode Control Register */
#define CMCR    0x10    /* Clock mode Control Register */
#define HCR     0x12    /* Hardware Configuration Register */
#define IVR     0x14    /* Interrupt Vector Register */
#define IOCR    0x16    /* Input/Output Control Register */
#define ICR     0x18    /* Interrupt Control Register */
#define DCCR    0x1a    /* Daisy Chain Control Register */
#define MISR    0x1c    /* Misc Interrupt status Register */
#define SICR    0x1e    /* status Interrupt Control Register */
#define RDR     0x20    /* Receive Data Register */
#define RMR     0x22    /* Receive mode Register */
#define RCSR    0x24    /* Receive Command/status Register */
#define RICR    0x26    /* Receive Interrupt Control Register */
#define RSR     0x28    /* Receive Sync Register */
#define RCLR    0x2a    /* Receive count Limit Register */
#define RCCR    0x2c    /* Receive Character count Register */
#define TC0R    0x2e    /* Time Constant 0 Register */
#define TDR     0x30    /* Transmit Data Register */
#define TMR     0x32    /* Transmit mode Register */
#define TCSR    0x34    /* Transmit Command/status Register */
#define TICR    0x36    /* Transmit Interrupt Control Register */
#define TSR     0x38    /* Transmit Sync Register */
#define TCLR    0x3a    /* Transmit count Limit Register */
#define TCCR    0x3c    /* Transmit Character count Register */
#define TC1R    0x3e    /* Time Constant 1 Register */


/*
 * MACRO DEFINITIONS FOR DMA REGISTERS
 */

#define DCR     0x06    /* DMA Control Register (shared) */
#define DACR    0x08    /* DMA Array count Register (shared) */
#define BDCR    0x12    /* Burst/Dwell Control Register (shared) */
#define DIVR    0x14    /* DMA Interrupt Vector Register (shared) */    
#define DICR    0x18    /* DMA Interrupt Control Register (shared) */
#define CDIR    0x1a    /* Clear DMA Interrupt Register (shared) */
#define SDIR    0x1c    /* Set DMA Interrupt Register (shared) */

#define TDMR    0x02    /* Transmit DMA mode Register */
#define TDIAR   0x1e    /* Transmit DMA Interrupt Arm Register */
#define TBCR    0x2a    /* Transmit Byte count Register */
#define TARL    0x2c    /* Transmit Address Register (low) */
#define TARU    0x2e    /* Transmit Address Register (high) */
#define NTBCR   0x3a    /* Next Transmit Byte count Register */
#define NTARL   0x3c    /* Next Transmit Address Register (low) */
#define NTARU   0x3e    /* Next Transmit Address Register (high) */

#define RDMR    0x82    /* Receive DMA mode Register (non-shared) */
#define RDIAR   0x9e    /* Receive DMA Interrupt Arm Register */
#define RBCR    0xaa    /* Receive Byte count Register */
#define RARL    0xac    /* Receive Address Register (low) */
#define RARU    0xae    /* Receive Address Register (high) */
#define NRBCR   0xba    /* Next Receive Byte count Register */
#define NRARL   0xbc    /* Next Receive Address Register (low) */
#define NRARU   0xbe    /* Next Receive Address Register (high) */


/*
 * MACRO DEFINITIONS FOR MODEM STATUS BITS
 */

#define MODEMSTATUS_DTR 0x80
#define MODEMSTATUS_DSR 0x40
#define MODEMSTATUS_RTS 0x20
#define MODEMSTATUS_CTS 0x10
#define MODEMSTATUS_RI  0x04
#define MODEMSTATUS_DCD 0x01


/*
 * Channel Command/Address Register (CCAR) Command Codes
 */

#define RTCmd_Null                      0x0000
#define RTCmd_ResetHighestIus           0x1000
#define RTCmd_TriggerChannelLoadDma     0x2000
#define RTCmd_TriggerRxDma              0x2800
#define RTCmd_TriggerTxDma              0x3000
#define RTCmd_TriggerRxAndTxDma         0x3800
#define RTCmd_PurgeRxFifo               0x4800
#define RTCmd_PurgeTxFifo               0x5000
#define RTCmd_PurgeRxAndTxFifo          0x5800
#define RTCmd_LoadRcc                   0x6800
#define RTCmd_LoadTcc                   0x7000
#define RTCmd_LoadRccAndTcc             0x7800
#define RTCmd_LoadTC0                   0x8800
#define RTCmd_LoadTC1                   0x9000
#define RTCmd_LoadTC0AndTC1             0x9800
#define RTCmd_SerialDataLSBFirst        0xa000
#define RTCmd_SerialDataMSBFirst        0xa800
#define RTCmd_SelectBigEndian           0xb000
#define RTCmd_SelectLittleEndian        0xb800


/*
 * DMA Command/Address Register (DCAR) Command Codes
 */

#define DmaCmd_Null                     0x0000
#define DmaCmd_ResetTxChannel           0x1000
#define DmaCmd_ResetRxChannel           0x1200
#define DmaCmd_StartTxChannel           0x2000
#define DmaCmd_StartRxChannel           0x2200
#define DmaCmd_ContinueTxChannel        0x3000
#define DmaCmd_ContinueRxChannel        0x3200
#define DmaCmd_PauseTxChannel           0x4000
#define DmaCmd_PauseRxChannel           0x4200
#define DmaCmd_AbortTxChannel           0x5000
#define DmaCmd_AbortRxChannel           0x5200
#define DmaCmd_InitTxChannel            0x7000
#define DmaCmd_InitRxChannel            0x7200
#define DmaCmd_ResetHighestDmaIus       0x8000
#define DmaCmd_ResetAllChannels         0x9000
#define DmaCmd_StartAllChannels         0xa000
#define DmaCmd_ContinueAllChannels      0xb000
#define DmaCmd_PauseAllChannels         0xc000
#define DmaCmd_AbortAllChannels         0xd000
#define DmaCmd_InitAllChannels          0xf000

#define TCmd_Null                       0x0000
#define TCmd_ClearTxCRC                 0x2000
#define TCmd_SelectTicrTtsaData         0x4000
#define TCmd_SelectTicrTxFifostatus     0x5000
#define TCmd_SelectTicrIntLevel         0x6000
#define TCmd_SelectTicrdma_level                0x7000
#define TCmd_SendFrame                  0x8000
#define TCmd_SendAbort                  0x9000
#define TCmd_EnableDleInsertion         0xc000
#define TCmd_DisableDleInsertion        0xd000
#define TCmd_ClearEofEom                0xe000
#define TCmd_SetEofEom                  0xf000

#define RCmd_Null                       0x0000
#define RCmd_ClearRxCRC                 0x2000
#define RCmd_EnterHuntmode              0x3000
#define RCmd_SelectRicrRtsaData         0x4000
#define RCmd_SelectRicrRxFifostatus     0x5000
#define RCmd_SelectRicrIntLevel         0x6000
#define RCmd_SelectRicrdma_level                0x7000

/*
 * Bits for enabling and disabling IRQs in Interrupt Control Register (ICR)
 */
 
#define RECEIVE_STATUS          BIT5
#define RECEIVE_DATA            BIT4
#define TRANSMIT_STATUS         BIT3
#define TRANSMIT_DATA           BIT2
#define IO_PIN                  BIT1
#define MISC                    BIT0


/*
 * Receive status Bits in Receive Command/status Register RCSR
 */

#define RXSTATUS_SHORT_FRAME            BIT8
#define RXSTATUS_CODE_VIOLATION         BIT8
#define RXSTATUS_EXITED_HUNT            BIT7
#define RXSTATUS_IDLE_RECEIVED          BIT6
#define RXSTATUS_BREAK_RECEIVED         BIT5
#define RXSTATUS_ABORT_RECEIVED         BIT5
#define RXSTATUS_RXBOUND                BIT4
#define RXSTATUS_CRC_ERROR              BIT3
#define RXSTATUS_FRAMING_ERROR          BIT3
#define RXSTATUS_ABORT                  BIT2
#define RXSTATUS_PARITY_ERROR           BIT2
#define RXSTATUS_OVERRUN                BIT1
#define RXSTATUS_DATA_AVAILABLE         BIT0
#define RXSTATUS_ALL                    0x01f6
#define usc_UnlatchRxstatusBits(a,b) usc_OutReg( (a), RCSR, (u16)((b) & RXSTATUS_ALL) )

/*
 * Values for setting transmit idle mode in 
 * Transmit Control/status Register (TCSR)
 */
#define IDLEMODE_FLAGS                  0x0000
#define IDLEMODE_ALT_ONE_ZERO           0x0100
#define IDLEMODE_ZERO                   0x0200
#define IDLEMODE_ONE                    0x0300
#define IDLEMODE_ALT_MARK_SPACE         0x0500
#define IDLEMODE_SPACE                  0x0600
#define IDLEMODE_MARK                   0x0700
#define IDLEMODE_MASK                   0x0700

/*
 * IUSC revision identifiers
 */
#define IUSC_SL1660                     0x4d44
#define IUSC_PRE_SL1660                 0x4553

/*
 * Transmit status Bits in Transmit Command/status Register (TCSR)
 */

#define TCSR_PRESERVE                   0x0F00

#define TCSR_UNDERWAIT                  BIT11
#define TXSTATUS_PREAMBLE_SENT          BIT7
#define TXSTATUS_IDLE_SENT              BIT6
#define TXSTATUS_ABORT_SENT             BIT5
#define TXSTATUS_EOF_SENT               BIT4
#define TXSTATUS_EOM_SENT               BIT4
#define TXSTATUS_CRC_SENT               BIT3
#define TXSTATUS_ALL_SENT               BIT2
#define TXSTATUS_UNDERRUN               BIT1
#define TXSTATUS_FIFO_EMPTY             BIT0
#define TXSTATUS_ALL                    0x00fa
#define usc_UnlatchTxstatusBits(a,b) usc_OutReg( (a), TCSR, (u16)((a)->tcsr_value + ((b) & 0x00FF)) )
                                

#define MISCSTATUS_RXC_LATCHED          BIT15
#define MISCSTATUS_RXC                  BIT14
#define MISCSTATUS_TXC_LATCHED          BIT13
#define MISCSTATUS_TXC                  BIT12
#define MISCSTATUS_RI_LATCHED           BIT11
#define MISCSTATUS_RI                   BIT10
#define MISCSTATUS_DSR_LATCHED          BIT9
#define MISCSTATUS_DSR                  BIT8
#define MISCSTATUS_DCD_LATCHED          BIT7
#define MISCSTATUS_DCD                  BIT6
#define MISCSTATUS_CTS_LATCHED          BIT5
#define MISCSTATUS_CTS                  BIT4
#define MISCSTATUS_RCC_UNDERRUN         BIT3
#define MISCSTATUS_DPLL_NO_SYNC         BIT2
#define MISCSTATUS_BRG1_ZERO            BIT1
#define MISCSTATUS_BRG0_ZERO            BIT0

#define usc_UnlatchIostatusBits(a,b) usc_OutReg((a),MISR,(u16)((b) & 0xaaa0))
#define usc_UnlatchMiscstatusBits(a,b) usc_OutReg((a),MISR,(u16)((b) & 0x000f))

#define SICR_RXC_ACTIVE                 BIT15
#define SICR_RXC_INACTIVE               BIT14
#define SICR_RXC                        (BIT15|BIT14)
#define SICR_TXC_ACTIVE                 BIT13
#define SICR_TXC_INACTIVE               BIT12
#define SICR_TXC                        (BIT13|BIT12)
#define SICR_RI_ACTIVE                  BIT11
#define SICR_RI_INACTIVE                BIT10
#define SICR_RI                         (BIT11|BIT10)
#define SICR_DSR_ACTIVE                 BIT9
#define SICR_DSR_INACTIVE               BIT8
#define SICR_DSR                        (BIT9|BIT8)
#define SICR_DCD_ACTIVE                 BIT7
#define SICR_DCD_INACTIVE               BIT6
#define SICR_DCD                        (BIT7|BIT6)
#define SICR_CTS_ACTIVE                 BIT5
#define SICR_CTS_INACTIVE               BIT4
#define SICR_CTS                        (BIT5|BIT4)
#define SICR_RCC_UNDERFLOW              BIT3
#define SICR_DPLL_NO_SYNC               BIT2
#define SICR_BRG1_ZERO                  BIT1
#define SICR_BRG0_ZERO                  BIT0

void usc_DisableMasterIrqBit( struct mgsl_struct *info );
void usc_EnableMasterIrqBit( struct mgsl_struct *info );
void usc_EnableInterrupts( struct mgsl_struct *info, u16 IrqMask );
void usc_DisableInterrupts( struct mgsl_struct *info, u16 IrqMask );
void usc_ClearIrqPendingBits( struct mgsl_struct *info, u16 IrqMask );

#define usc_EnableInterrupts( a, b ) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0xff00) + 0xc0 + (b)) )

#define usc_DisableInterrupts( a, b ) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0xff00) + 0x80 + (b)) )

#define usc_EnableMasterIrqBit(a) \
        usc_OutReg( (a), ICR, (u16)((usc_InReg((a),ICR) & 0x0f00) + 0xb000) )

#define usc_DisableMasterIrqBit(a) \
        usc_OutReg( (a), ICR, (u16)(usc_InReg((a),ICR) & 0x7f00) )

#define usc_ClearIrqPendingBits( a, b ) usc_OutReg( (a), DCCR, 0x40 + (b) )

/*
 * Transmit status Bits in Transmit Control status Register (TCSR)
 * and Transmit Interrupt Control Register (TICR) (except BIT2, BIT0)
 */

#define TXSTATUS_PREAMBLE_SENT  BIT7
#define TXSTATUS_IDLE_SENT      BIT6
#define TXSTATUS_ABORT_SENT     BIT5
#define TXSTATUS_EOF            BIT4
#define TXSTATUS_CRC_SENT       BIT3
#define TXSTATUS_ALL_SENT       BIT2
#define TXSTATUS_UNDERRUN       BIT1
#define TXSTATUS_FIFO_EMPTY     BIT0

#define DICR_MASTER             BIT15
#define DICR_TRANSMIT           BIT0
#define DICR_RECEIVE            BIT1

#define usc_EnableDmaInterrupts(a,b) \
        usc_OutDmaReg( (a), DICR, (u16)(usc_InDmaReg((a),DICR) | (b)) )

#define usc_DisableDmaInterrupts(a,b) \
        usc_OutDmaReg( (a), DICR, (u16)(usc_InDmaReg((a),DICR) & ~(b)) )

#define usc_EnableStatusIrqs(a,b) \
        usc_OutReg( (a), SICR, (u16)(usc_InReg((a),SICR) | (b)) )

#define usc_DisablestatusIrqs(a,b) \
        usc_OutReg( (a), SICR, (u16)(usc_InReg((a),SICR) & ~(b)) )

/* Transmit status Bits in Transmit Control status Register (TCSR) */
/* and Transmit Interrupt Control Register (TICR) (except BIT2, BIT0) */


#define DISABLE_UNCONDITIONAL    0
#define DISABLE_END_OF_FRAME     1
#define ENABLE_UNCONDITIONAL     2
#define ENABLE_AUTO_CTS          3
#define ENABLE_AUTO_DCD          3
#define usc_EnableTransmitter(a,b) \
        usc_OutReg( (a), TMR, (u16)((usc_InReg((a),TMR) & 0xfffc) | (b)) )
#define usc_EnableReceiver(a,b) \
        usc_OutReg( (a), RMR, (u16)((usc_InReg((a),RMR) & 0xfffc) | (b)) )

static u16  usc_InDmaReg( struct mgsl_struct *info, u16 Port );
static void usc_OutDmaReg( struct mgsl_struct *info, u16 Port, u16 Value );
static void usc_DmaCmd( struct mgsl_struct *info, u16 Cmd );

static u16  usc_InReg( struct mgsl_struct *info, u16 Port );
static void usc_OutReg( struct mgsl_struct *info, u16 Port, u16 Value );
static void usc_RTCmd( struct mgsl_struct *info, u16 Cmd );
void usc_RCmd( struct mgsl_struct *info, u16 Cmd );
void usc_TCmd( struct mgsl_struct *info, u16 Cmd );

#define usc_TCmd(a,b) usc_OutReg((a), TCSR, (u16)((a)->tcsr_value + (b)))
#define usc_RCmd(a,b) usc_OutReg((a), RCSR, (b))

#define usc_SetTransmitSyncChars(a,s0,s1) usc_OutReg((a), TSR, (u16)(((u16)s0<<8)|(u16)s1))

static void usc_process_rxoverrun_sync( struct mgsl_struct *info );
static void usc_start_receiver( struct mgsl_struct *info );
static void usc_stop_receiver( struct mgsl_struct *info );

static void usc_start_transmitter( struct mgsl_struct *info );
static void usc_stop_transmitter( struct mgsl_struct *info );
static void usc_set_txidle( struct mgsl_struct *info );
static void usc_load_txfifo( struct mgsl_struct *info );

static void usc_enable_aux_clock( struct mgsl_struct *info, u32 DataRate );
static void usc_enable_loopback( struct mgsl_struct *info, int enable );

static void usc_get_serial_signals( struct mgsl_struct *info );
static void usc_set_serial_signals( struct mgsl_struct *info );

static void usc_reset( struct mgsl_struct *info );

static void usc_set_sync_mode( struct mgsl_struct *info );
static void usc_set_sdlc_mode( struct mgsl_struct *info );
static void usc_set_async_mode( struct mgsl_struct *info );
static void usc_enable_async_clock( struct mgsl_struct *info, u32 DataRate );

static void usc_loopback_frame( struct mgsl_struct *info );

static void mgsl_tx_timeout(struct timer_list *t);


static void usc_loopmode_cancel_transmit( struct mgsl_struct * info );
static void usc_loopmode_insert_request( struct mgsl_struct * info );
static int usc_loopmode_active( struct mgsl_struct * info);
static void usc_loopmode_send_done( struct mgsl_struct * info );

static int mgsl_ioctl_common(struct mgsl_struct *info, unsigned int cmd, unsigned long arg);

#if SYNCLINK_GENERIC_HDLC
#define dev_to_port(D) (dev_to_hdlc(D)->priv)
static void hdlcdev_tx_done(struct mgsl_struct *info);
static void hdlcdev_rx(struct mgsl_struct *info, char *buf, int size);
static int  hdlcdev_init(struct mgsl_struct *info);
static void hdlcdev_exit(struct mgsl_struct *info);
#endif

/*
 * Defines a BUS descriptor value for the PCI adapter
 * local bus address ranges.
 */

#define BUS_DESCRIPTOR( WrHold, WrDly, RdDly, Nwdd, Nwad, Nxda, Nrdd, Nrad ) \
(0x00400020 + \
((WrHold) << 30) + \
((WrDly)  << 28) + \
((RdDly)  << 26) + \
((Nwdd)   << 20) + \
((Nwad)   << 15) + \
((Nxda)   << 13) + \
((Nrdd)   << 11) + \
((Nrad)   <<  6) )

static void mgsl_trace_block(struct mgsl_struct *info,const char* data, int count, int xmit);

/*
 * Adapter diagnostic routines
 */
static bool mgsl_register_test( struct mgsl_struct *info );
static bool mgsl_irq_test( struct mgsl_struct *info );
static bool mgsl_dma_test( struct mgsl_struct *info );
static bool mgsl_memory_test( struct mgsl_struct *info );
static int mgsl_adapter_test( struct mgsl_struct *info );

/*
 * device and resource management routines
 */
static int mgsl_claim_resources(struct mgsl_struct *info);
static void mgsl_release_resources(struct mgsl_struct *info);
static void mgsl_add_device(struct mgsl_struct *info);
static struct mgsl_struct* mgsl_allocate_device(void);

/*
 * DMA buffer manupulation functions.
 */
static void mgsl_free_rx_frame_buffers( struct mgsl_struct *info, unsigned int StartIndex, unsigned int EndIndex );
static bool mgsl_get_rx_frame( struct mgsl_struct *info );
static bool mgsl_get_raw_rx_frame( struct mgsl_struct *info );
static void mgsl_reset_rx_dma_buffers( struct mgsl_struct *info );
static void mgsl_reset_tx_dma_buffers( struct mgsl_struct *info );
static int num_free_tx_dma_buffers(struct mgsl_struct *info);
static void mgsl_load_tx_dma_buffer( struct mgsl_struct *info, const char *Buffer, unsigned int BufferSize);
static void mgsl_load_pci_memory(char* TargetPtr, const char* SourcePtr, unsigned short count);

/*
 * DMA and Shared Memory buffer allocation and formatting
 */
static int  mgsl_allocate_dma_buffers(struct mgsl_struct *info);
static void mgsl_free_dma_buffers(struct mgsl_struct *info);
static int  mgsl_alloc_frame_memory(struct mgsl_struct *info, DMABUFFERENTRY *BufferList,int Buffercount);
static void mgsl_free_frame_memory(struct mgsl_struct *info, DMABUFFERENTRY *BufferList,int Buffercount);
static int  mgsl_alloc_buffer_list_memory(struct mgsl_struct *info);
static void mgsl_free_buffer_list_memory(struct mgsl_struct *info);
static int mgsl_alloc_intermediate_rxbuffer_memory(struct mgsl_struct *info);
static void mgsl_free_intermediate_rxbuffer_memory(struct mgsl_struct *info);
static int mgsl_alloc_intermediate_txbuffer_memory(struct mgsl_struct *info);
static void mgsl_free_intermediate_txbuffer_memory(struct mgsl_struct *info);
static bool load_next_tx_holding_buffer(struct mgsl_struct *info);
static int save_tx_buffer_request(struct mgsl_struct *info,const char *Buffer, unsigned int BufferSize);

/*
 * Bottom half interrupt handlers
 */
static void mgsl_bh_handler(struct work_struct *work);
static void mgsl_bh_receive(struct mgsl_struct *info);
static void mgsl_bh_transmit(struct mgsl_struct *info);
static void mgsl_bh_status(struct mgsl_struct *info);

/*
 * Interrupt handler routines and dispatch table.
 */
static void mgsl_isr_null( struct mgsl_struct *info );
static void mgsl_isr_transmit_data( struct mgsl_struct *info );
static void mgsl_isr_receive_data( struct mgsl_struct *info );
static void mgsl_isr_receive_status( struct mgsl_struct *info );
static void mgsl_isr_transmit_status( struct mgsl_struct *info );
static void mgsl_isr_io_pin( struct mgsl_struct *info );
static void mgsl_isr_misc( struct mgsl_struct *info );
static void mgsl_isr_receive_dma( struct mgsl_struct *info );
static void mgsl_isr_transmit_dma( struct mgsl_struct *info );

typedef void (*isr_dispatch_func)(struct mgsl_struct *);

static isr_dispatch_func UscIsrTable[7] =
{
        mgsl_isr_null,
        mgsl_isr_misc,
        mgsl_isr_io_pin,
        mgsl_isr_transmit_data,
        mgsl_isr_transmit_status,
        mgsl_isr_receive_data,
        mgsl_isr_receive_status
};

/*
 * ioctl call handlers
 */
static int tiocmget(struct tty_struct *tty);
static int tiocmset(struct tty_struct *tty,
                    unsigned int set, unsigned int clear);
static int mgsl_get_stats(struct mgsl_struct * info, struct mgsl_icount
        __user *user_icount);
static int mgsl_get_params(struct mgsl_struct * info, MGSL_PARAMS  __user *user_params);
static int mgsl_set_params(struct mgsl_struct * info, MGSL_PARAMS  __user *new_params);
static int mgsl_get_txidle(struct mgsl_struct * info, int __user *idle_mode);
static int mgsl_set_txidle(struct mgsl_struct * info, int idle_mode);
static int mgsl_txenable(struct mgsl_struct * info, int enable);
static int mgsl_txabort(struct mgsl_struct * info);
static int mgsl_rxenable(struct mgsl_struct * info, int enable);
static int mgsl_wait_event(struct mgsl_struct * info, int __user *mask);
static int mgsl_loopmode_send_done( struct mgsl_struct * info );

/* set non-zero on successful registration with PCI subsystem */
static bool pci_registered;

/*
 * Global linked list of SyncLink devices
 */
static struct mgsl_struct *mgsl_device_list;
static int mgsl_device_count;

/*
 * Set this param to non-zero to load eax with the
 * .text section address and breakpoint on module load.
 * This is useful for use with gdb and add-symbol-file command.
 */
static bool break_on_load;

/*
 * Driver major number, defaults to zero to get auto
 * assigned major number. May be forced as module parameter.
 */
static int ttymajor;

/*
 * Array of user specified options for ISA adapters.
 */
static int io[MAX_ISA_DEVICES];
static int irq[MAX_ISA_DEVICES];
static int dma[MAX_ISA_DEVICES];
static int debug_level;
static int maxframe[MAX_TOTAL_DEVICES];
static int txdmabufs[MAX_TOTAL_DEVICES];
static int txholdbufs[MAX_TOTAL_DEVICES];
        
module_param(break_on_load, bool, 0);
module_param(ttymajor, int, 0);
module_param_hw_array(io, int, ioport, NULL, 0);
module_param_hw_array(irq, int, irq, NULL, 0);
module_param_hw_array(dma, int, dma, NULL, 0);
module_param(debug_level, int, 0);
module_param_array(maxframe, int, NULL, 0);
module_param_array(txdmabufs, int, NULL, 0);
module_param_array(txholdbufs, int, NULL, 0);

static char *driver_name = "SyncLink serial driver";
static char *driver_version = "$Revision: 4.38 $";

static int synclink_init_one (struct pci_dev *dev,
                                     const struct pci_device_id *ent);
static void synclink_remove_one (struct pci_dev *dev);

static const struct pci_device_id synclink_pci_tbl[] = {
        { PCI_VENDOR_ID_MICROGATE, PCI_DEVICE_ID_MICROGATE_USC, PCI_ANY_ID, PCI_ANY_ID, },
        { PCI_VENDOR_ID_MICROGATE, 0x0210, PCI_ANY_ID, PCI_ANY_ID, },
        { 0, }, /* terminate list */
};
MODULE_DEVICE_TABLE(pci, synclink_pci_tbl);

MODULE_LICENSE("GPL");

static struct pci_driver synclink_pci_driver = {
        .name           = "synclink",
        .id_table       = synclink_pci_tbl,
        .probe          = synclink_init_one,
        .remove         = synclink_remove_one,
};

static struct tty_driver *serial_driver;

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256


static void mgsl_change_params(struct mgsl_struct *info);
static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout);

/*
 * 1st function defined in .text section. Calling this function in
 * init_module() followed by a breakpoint allows a remote debugger
 * (gdb) to get the .text address for the add-symbol-file command.
 * This allows remote debugging of dynamically loadable modules.
 */
static void* mgsl_get_text_ptr(void)
{
        return mgsl_get_text_ptr;
}

static inline int mgsl_paranoia_check(struct mgsl_struct *info,
                                        char *name, const char *routine)
{
#ifdef MGSL_PARANOIA_CHECK
        static const char *badmagic =
                "Warning: bad magic number for mgsl struct (%s) in %s\n";
        static const char *badinfo =
                "Warning: null mgsl_struct for (%s) in %s\n";

        if (!info) {
                printk(badinfo, name, routine);
                return 1;
        }
        if (info->magic != MGSL_MAGIC) {
                printk(badmagic, name, routine);
                return 1;
        }
#else
        if (!info)
                return 1;
#endif
        return 0;
}

/**
 * line discipline callback wrappers
 *
 * The wrappers maintain line discipline references
 * while calling into the line discipline.
 *
 * ldisc_receive_buf  - pass receive data to line discipline
 */

static void ldisc_receive_buf(struct tty_struct *tty,
                              const __u8 *data, char *flags, int count)
{
        struct tty_ldisc *ld;
        if (!tty)
                return;
        ld = tty_ldisc_ref(tty);
        if (ld) {
                if (ld->ops->receive_buf)
                        ld->ops->receive_buf(tty, data, flags, count);
                tty_ldisc_deref(ld);
        }
}

/* mgsl_stop()          throttle (stop) transmitter
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_stop(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_stop"))
                return;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("mgsl_stop(%s)\n",info->device_name);    
                
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (info->tx_enabled)
                usc_stop_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_stop() */

/* mgsl_start()         release (start) transmitter
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_start(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_start"))
                return;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("mgsl_start(%s)\n",info->device_name);   
                
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (!info->tx_enabled)
                usc_start_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_start() */

/*
 * Bottom half work queue access functions
 */

/* mgsl_bh_action()     Return next bottom half action to perform.
 * Return Value:        BH action code or 0 if nothing to do.
 */
static int mgsl_bh_action(struct mgsl_struct *info)
{
        unsigned long flags;
        int rc = 0;
        
        spin_lock_irqsave(&info->irq_spinlock,flags);

        if (info->pending_bh & BH_RECEIVE) {
                info->pending_bh &= ~BH_RECEIVE;
                rc = BH_RECEIVE;
        } else if (info->pending_bh & BH_TRANSMIT) {
                info->pending_bh &= ~BH_TRANSMIT;
                rc = BH_TRANSMIT;
        } else if (info->pending_bh & BH_STATUS) {
                info->pending_bh &= ~BH_STATUS;
                rc = BH_STATUS;
        }

        if (!rc) {
                /* Mark BH routine as complete */
                info->bh_running = false;
                info->bh_requested = false;
        }
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        return rc;
}

/*
 *      Perform bottom half processing of work items queued by ISR.
 */
static void mgsl_bh_handler(struct work_struct *work)
{
        struct mgsl_struct *info =
                container_of(work, struct mgsl_struct, task);
        int action;

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_handler(%s) entry\n",
                        __FILE__,__LINE__,info->device_name);
        
        info->bh_running = true;

        while((action = mgsl_bh_action(info)) != 0) {
        
                /* Process work item */
                if ( debug_level >= DEBUG_LEVEL_BH )
                        printk( "%s(%d):mgsl_bh_handler() work item action=%d\n",
                                __FILE__,__LINE__,action);

                switch (action) {
                
                case BH_RECEIVE:
                        mgsl_bh_receive(info);
                        break;
                case BH_TRANSMIT:
                        mgsl_bh_transmit(info);
                        break;
                case BH_STATUS:
                        mgsl_bh_status(info);
                        break;
                default:
                        /* unknown work item ID */
                        printk("Unknown work item ID=%08X!\n", action);
                        break;
                }
        }

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_handler(%s) exit\n",
                        __FILE__,__LINE__,info->device_name);
}

static void mgsl_bh_receive(struct mgsl_struct *info)
{
        bool (*get_rx_frame)(struct mgsl_struct *info) =
                (info->params.mode == MGSL_MODE_HDLC ? mgsl_get_rx_frame : mgsl_get_raw_rx_frame);

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_receive(%s)\n",
                        __FILE__,__LINE__,info->device_name);
        
        do
        {
                if (info->rx_rcc_underrun) {
                        unsigned long flags;
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        usc_start_receiver(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        return;
                }
        } while(get_rx_frame(info));
}

static void mgsl_bh_transmit(struct mgsl_struct *info)
{
        struct tty_struct *tty = info->port.tty;
        unsigned long flags;
        
        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_transmit() entry on %s\n",
                        __FILE__,__LINE__,info->device_name);

        if (tty)
                tty_wakeup(tty);

        /* if transmitter idle and loopmode_send_done_requested
         * then start echoing RxD to TxD
         */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( !info->tx_active && info->loopmode_send_done_requested )
                usc_loopmode_send_done( info );
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}

static void mgsl_bh_status(struct mgsl_struct *info)
{
        if ( debug_level >= DEBUG_LEVEL_BH )
                printk( "%s(%d):mgsl_bh_status() entry on %s\n",
                        __FILE__,__LINE__,info->device_name);

        info->ri_chkcount = 0;
        info->dsr_chkcount = 0;
        info->dcd_chkcount = 0;
        info->cts_chkcount = 0;
}

/* mgsl_isr_receive_status()
 * 
 *      Service a receive status interrupt. The type of status
 *      interrupt is indicated by the state of the RCSR.
 *      This is only used for HDLC mode.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_status( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, RCSR );

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):mgsl_isr_receive_status status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        if ( (status & RXSTATUS_ABORT_RECEIVED) && 
                info->loopmode_insert_requested &&
                usc_loopmode_active(info) )
        {
                ++info->icount.rxabort;
                info->loopmode_insert_requested = false;
 
                /* clear CMR:13 to start echoing RxD to TxD */
                info->cmr_value &= ~BIT13;
                usc_OutReg(info, CMR, info->cmr_value);
 
                /* disable received abort irq (no longer required) */
                usc_OutReg(info, RICR,
                        (usc_InReg(info, RICR) & ~RXSTATUS_ABORT_RECEIVED));
        }

        if (status & (RXSTATUS_EXITED_HUNT | RXSTATUS_IDLE_RECEIVED)) {
                if (status & RXSTATUS_EXITED_HUNT)
                        info->icount.exithunt++;
                if (status & RXSTATUS_IDLE_RECEIVED)
                        info->icount.rxidle++;
                wake_up_interruptible(&info->event_wait_q);
        }

        if (status & RXSTATUS_OVERRUN){
                info->icount.rxover++;
                usc_process_rxoverrun_sync( info );
        }

        usc_ClearIrqPendingBits( info, RECEIVE_STATUS );
        usc_UnlatchRxstatusBits( info, status );

}       /* end of mgsl_isr_receive_status() */

/* mgsl_isr_transmit_status()
 * 
 *      Service a transmit status interrupt
 *      HDLC mode :end of transmit frame
 *      Async mode:all data is sent
 *      transmit status is indicated by bits in the TCSR.
 * 
 * Arguments:           info           pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_status( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, TCSR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_transmit_status status=%04X\n",
                        __FILE__,__LINE__,status);
        
        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS );
        usc_UnlatchTxstatusBits( info, status );
        
        if ( status & (TXSTATUS_UNDERRUN | TXSTATUS_ABORT_SENT) )
        {
                /* finished sending HDLC abort. This may leave  */
                /* the TxFifo with data from the aborted frame  */
                /* so purge the TxFifo. Also shutdown the DMA   */
                /* channel in case there is data remaining in   */
                /* the DMA buffer                               */
                usc_DmaCmd( info, DmaCmd_ResetTxChannel );
                usc_RTCmd( info, RTCmd_PurgeTxFifo );
        }
 
        if ( status & TXSTATUS_EOF_SENT )
                info->icount.txok++;
        else if ( status & TXSTATUS_UNDERRUN )
                info->icount.txunder++;
        else if ( status & TXSTATUS_ABORT_SENT )
                info->icount.txabort++;
        else
                info->icount.txunder++;
                        
        info->tx_active = false;
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        del_timer(&info->tx_timer);     
        
        if ( info->drop_rts_on_tx_done ) {
                usc_get_serial_signals( info );
                if ( info->serial_signals & SerialSignal_RTS ) {
                        info->serial_signals &= ~SerialSignal_RTS;
                        usc_set_serial_signals( info );
                }
                info->drop_rts_on_tx_done = false;
        }

#if SYNCLINK_GENERIC_HDLC
        if (info->netcount)
                hdlcdev_tx_done(info);
        else 
#endif
        {
                if (info->port.tty->stopped || info->port.tty->hw_stopped) {
                        usc_stop_transmitter(info);
                        return;
                }
                info->pending_bh |= BH_TRANSMIT;
        }

}       /* end of mgsl_isr_transmit_status() */

/* mgsl_isr_io_pin()
 * 
 *      Service an Input/Output pin interrupt. The type of
 *      interrupt is indicated by bits in the MISR
 *      
 * Arguments:           info           pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_io_pin( struct mgsl_struct *info )
{
        struct  mgsl_icount *icount;
        u16 status = usc_InReg( info, MISR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_io_pin status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        usc_ClearIrqPendingBits( info, IO_PIN );
        usc_UnlatchIostatusBits( info, status );

        if (status & (MISCSTATUS_CTS_LATCHED | MISCSTATUS_DCD_LATCHED |
                      MISCSTATUS_DSR_LATCHED | MISCSTATUS_RI_LATCHED) ) {
                icount = &info->icount;
                /* update input line counters */
                if (status & MISCSTATUS_RI_LATCHED) {
                        if ((info->ri_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_RI);
                        icount->rng++;
                        if ( status & MISCSTATUS_RI )
                                info->input_signal_events.ri_up++;      
                        else
                                info->input_signal_events.ri_down++;    
                }
                if (status & MISCSTATUS_DSR_LATCHED) {
                        if ((info->dsr_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_DSR);
                        icount->dsr++;
                        if ( status & MISCSTATUS_DSR )
                                info->input_signal_events.dsr_up++;
                        else
                                info->input_signal_events.dsr_down++;
                }
                if (status & MISCSTATUS_DCD_LATCHED) {
                        if ((info->dcd_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_DCD);
                        icount->dcd++;
                        if (status & MISCSTATUS_DCD) {
                                info->input_signal_events.dcd_up++;
                        } else
                                info->input_signal_events.dcd_down++;
#if SYNCLINK_GENERIC_HDLC
                        if (info->netcount) {
                                if (status & MISCSTATUS_DCD)
                                        netif_carrier_on(info->netdev);
                                else
                                        netif_carrier_off(info->netdev);
                        }
#endif
                }
                if (status & MISCSTATUS_CTS_LATCHED)
                {
                        if ((info->cts_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
                                usc_DisablestatusIrqs(info,SICR_CTS);
                        icount->cts++;
                        if ( status & MISCSTATUS_CTS )
                                info->input_signal_events.cts_up++;
                        else
                                info->input_signal_events.cts_down++;
                }
                wake_up_interruptible(&info->status_event_wait_q);
                wake_up_interruptible(&info->event_wait_q);

                if (tty_port_check_carrier(&info->port) &&
                     (status & MISCSTATUS_DCD_LATCHED) ) {
                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                printk("%s CD now %s...", info->device_name,
                                       (status & MISCSTATUS_DCD) ? "on" : "off");
                        if (status & MISCSTATUS_DCD)
                                wake_up_interruptible(&info->port.open_wait);
                        else {
                                if ( debug_level >= DEBUG_LEVEL_ISR )
                                        printk("doing serial hangup...");
                                if (info->port.tty)
                                        tty_hangup(info->port.tty);
                        }
                }
        
                if (tty_port_cts_enabled(&info->port) &&
                     (status & MISCSTATUS_CTS_LATCHED) ) {
                        if (info->port.tty->hw_stopped) {
                                if (status & MISCSTATUS_CTS) {
                                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                                printk("CTS tx start...");
                                        info->port.tty->hw_stopped = 0;
                                        usc_start_transmitter(info);
                                        info->pending_bh |= BH_TRANSMIT;
                                        return;
                                }
                        } else {
                                if (!(status & MISCSTATUS_CTS)) {
                                        if ( debug_level >= DEBUG_LEVEL_ISR )
                                                printk("CTS tx stop...");
                                        if (info->port.tty)
                                                info->port.tty->hw_stopped = 1;
                                        usc_stop_transmitter(info);
                                }
                        }
                }
        }

        info->pending_bh |= BH_STATUS;
        
        /* for diagnostics set IRQ flag */
        if ( status & MISCSTATUS_TXC_LATCHED ){
                usc_OutReg( info, SICR,
                        (unsigned short)(usc_InReg(info,SICR) & ~(SICR_TXC_ACTIVE+SICR_TXC_INACTIVE)) );
                usc_UnlatchIostatusBits( info, MISCSTATUS_TXC_LATCHED );
                info->irq_occurred = true;
        }

}       /* end of mgsl_isr_io_pin() */

/* mgsl_isr_transmit_data()
 * 
 *      Service a transmit data interrupt (async mode only).
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_data( struct mgsl_struct *info )
{
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_transmit_data xmit_cnt=%d\n",
                        __FILE__,__LINE__,info->xmit_cnt);
                        
        usc_ClearIrqPendingBits( info, TRANSMIT_DATA );
        
        if (info->port.tty->stopped || info->port.tty->hw_stopped) {
                usc_stop_transmitter(info);
                return;
        }
        
        if ( info->xmit_cnt )
                usc_load_txfifo( info );
        else
                info->tx_active = false;
                
        if (info->xmit_cnt < WAKEUP_CHARS)
                info->pending_bh |= BH_TRANSMIT;

}       /* end of mgsl_isr_transmit_data() */

/* mgsl_isr_receive_data()
 * 
 *      Service a receive data interrupt. This occurs
 *      when operating in asynchronous interrupt transfer mode.
 *      The receive data FIFO is flushed to the receive data buffers. 
 * 
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_data( struct mgsl_struct *info )
{
        int Fifocount;
        u16 status;
        int work = 0;
        unsigned char DataByte;
        struct  mgsl_icount *icount = &info->icount;
        
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_receive_data\n",
                        __FILE__,__LINE__);

        usc_ClearIrqPendingBits( info, RECEIVE_DATA );
        
        /* select FIFO status for RICR readback */
        usc_RCmd( info, RCmd_SelectRicrRxFifostatus );

        /* clear the Wordstatus bit so that status readback */
        /* only reflects the status of this byte */
        usc_OutReg( info, RICR+LSBONLY, (u16)(usc_InReg(info, RICR+LSBONLY) & ~BIT3 ));

        /* flush the receive FIFO */

        while( (Fifocount = (usc_InReg(info,RICR) >> 8)) ) {
                int flag;

                /* read one byte from RxFIFO */
                outw( (inw(info->io_base + CCAR) & 0x0780) | (RDR+LSBONLY),
                      info->io_base + CCAR );
                DataByte = inb( info->io_base + CCAR );

                /* get the status of the received byte */
                status = usc_InReg(info, RCSR);
                if ( status & (RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR |
                                RXSTATUS_OVERRUN | RXSTATUS_BREAK_RECEIVED) )
                        usc_UnlatchRxstatusBits(info,RXSTATUS_ALL);
                
                icount->rx++;
                
                flag = 0;
                if ( status & (RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR |
                                RXSTATUS_OVERRUN | RXSTATUS_BREAK_RECEIVED) ) {
                        printk("rxerr=%04X\n",status);
                        /* update error statistics */
                        if ( status & RXSTATUS_BREAK_RECEIVED ) {
                                status &= ~(RXSTATUS_FRAMING_ERROR | RXSTATUS_PARITY_ERROR);
                                icount->brk++;
                        } else if (status & RXSTATUS_PARITY_ERROR)
                                icount->parity++;
                        else if (status & RXSTATUS_FRAMING_ERROR)
                                icount->frame++;
                        else if (status & RXSTATUS_OVERRUN) {
                                /* must issue purge fifo cmd before */
                                /* 16C32 accepts more receive chars */
                                usc_RTCmd(info,RTCmd_PurgeRxFifo);
                                icount->overrun++;
                        }

                        /* discard char if tty control flags say so */
                        if (status & info->ignore_status_mask)
                                continue;
                                
                        status &= info->read_status_mask;
                
                        if (status & RXSTATUS_BREAK_RECEIVED) {
                                flag = TTY_BREAK;
                                if (info->port.flags & ASYNC_SAK)
                                        do_SAK(info->port.tty);
                        } else if (status & RXSTATUS_PARITY_ERROR)
                                flag = TTY_PARITY;
                        else if (status & RXSTATUS_FRAMING_ERROR)
                                flag = TTY_FRAME;
                }       /* end of if (error) */
                tty_insert_flip_char(&info->port, DataByte, flag);
                if (status & RXSTATUS_OVERRUN) {
                        /* Overrun is special, since it's
                         * reported immediately, and doesn't
                         * affect the current character
                         */
                        work += tty_insert_flip_char(&info->port, 0, TTY_OVERRUN);
                }
        }

        if ( debug_level >= DEBUG_LEVEL_ISR ) {
                printk("%s(%d):rx=%d brk=%d parity=%d frame=%d overrun=%d\n",
                        __FILE__,__LINE__,icount->rx,icount->brk,
                        icount->parity,icount->frame,icount->overrun);
        }
                        
        if(work)
                tty_flip_buffer_push(&info->port);
}

/* mgsl_isr_misc()
 * 
 *      Service a miscellaneous interrupt source.
 *      
 * Arguments:           info            pointer to device extension (instance data)
 * Return Value:        None
 */
static void mgsl_isr_misc( struct mgsl_struct *info )
{
        u16 status = usc_InReg( info, MISR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_misc status=%04X\n",
                        __FILE__,__LINE__,status);
                        
        if ((status & MISCSTATUS_RCC_UNDERRUN) &&
            (info->params.mode == MGSL_MODE_HDLC)) {

                /* turn off receiver and rx DMA */
                usc_EnableReceiver(info,DISABLE_UNCONDITIONAL);
                usc_DmaCmd(info, DmaCmd_ResetRxChannel);
                usc_UnlatchRxstatusBits(info, RXSTATUS_ALL);
                usc_ClearIrqPendingBits(info, RECEIVE_DATA | RECEIVE_STATUS);
                usc_DisableInterrupts(info, RECEIVE_DATA | RECEIVE_STATUS);

                /* schedule BH handler to restart receiver */
                info->pending_bh |= BH_RECEIVE;
                info->rx_rcc_underrun = true;
        }

        usc_ClearIrqPendingBits( info, MISC );
        usc_UnlatchMiscstatusBits( info, status );

}       /* end of mgsl_isr_misc() */

/* mgsl_isr_null()
 *
 *      Services undefined interrupt vectors from the
 *      USC. (hence this function SHOULD never be called)
 * 
 * Arguments:           info            pointer to device extension (instance data)
 * Return Value:        None
 */
static void mgsl_isr_null( struct mgsl_struct *info )
{

}       /* end of mgsl_isr_null() */

/* mgsl_isr_receive_dma()
 * 
 *      Service a receive DMA channel interrupt.
 *      For this driver there are two sources of receive DMA interrupts
 *      as identified in the Receive DMA mode Register (RDMR):
 * 
 *      BIT3    EOA/EOL         End of List, all receive buffers in receive
 *                              buffer list have been filled (no more free buffers
 *                              available). The DMA controller has shut down.
 * 
 *      BIT2    EOB             End of Buffer. This interrupt occurs when a receive
 *                              DMA buffer is terminated in response to completion
 *                              of a good frame or a frame with errors. The status
 *                              of the frame is stored in the buffer entry in the
 *                              list of receive buffer entries.
 * 
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_receive_dma( struct mgsl_struct *info )
{
        u16 status;
        
        /* clear interrupt pending and IUS bit for Rx DMA IRQ */
        usc_OutDmaReg( info, CDIR, BIT9 | BIT1 );

        /* Read the receive DMA status to identify interrupt type. */
        /* This also clears the status bits. */
        status = usc_InDmaReg( info, RDMR );

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk("%s(%d):mgsl_isr_receive_dma(%s) status=%04X\n",
                        __FILE__,__LINE__,info->device_name,status);
                        
        info->pending_bh |= BH_RECEIVE;
        
        if ( status & BIT3 ) {
                info->rx_overflow = true;
                info->icount.buf_overrun++;
        }

}       /* end of mgsl_isr_receive_dma() */

/* mgsl_isr_transmit_dma()
 *
 *      This function services a transmit DMA channel interrupt.
 *
 *      For this driver there is one source of transmit DMA interrupts
 *      as identified in the Transmit DMA Mode Register (TDMR):
 *
 *      BIT2  EOB       End of Buffer. This interrupt occurs when a
 *                      transmit DMA buffer has been emptied.
 *
 *      The driver maintains enough transmit DMA buffers to hold at least
 *      one max frame size transmit frame. When operating in a buffered
 *      transmit mode, there may be enough transmit DMA buffers to hold at
 *      least two or more max frame size frames. On an EOB condition,
 *      determine if there are any queued transmit buffers and copy into
 *      transmit DMA buffers if we have room.
 *
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void mgsl_isr_transmit_dma( struct mgsl_struct *info )
{
        u16 status;

        /* clear interrupt pending and IUS bit for Tx DMA IRQ */
        usc_OutDmaReg(info, CDIR, BIT8 | BIT0 );

        /* Read the transmit DMA status to identify interrupt type. */
        /* This also clears the status bits. */

        status = usc_InDmaReg( info, TDMR );

        if ( debug_level >= DEBUG_LEVEL_ISR )
                printk("%s(%d):mgsl_isr_transmit_dma(%s) status=%04X\n",
                        __FILE__,__LINE__,info->device_name,status);

        if ( status & BIT2 ) {
                --info->tx_dma_buffers_used;

                /* if there are transmit frames queued,
                 *  try to load the next one
                 */
                if ( load_next_tx_holding_buffer(info) ) {
                        /* if call returns non-zero value, we have
                         * at least one free tx holding buffer
                         */
                        info->pending_bh |= BH_TRANSMIT;
                }
        }

}       /* end of mgsl_isr_transmit_dma() */

/* mgsl_interrupt()
 * 
 *      Interrupt service routine entry point.
 *      
 * Arguments:
 * 
 *      irq             interrupt number that caused interrupt
 *      dev_id          device ID supplied during interrupt registration
 *      
 * Return Value: None
 */
static irqreturn_t mgsl_interrupt(int dummy, void *dev_id)
{
        struct mgsl_struct *info = dev_id;
        u16 UscVector;
        u16 DmaVector;

        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk(KERN_DEBUG "%s(%d):mgsl_interrupt(%d)entry.\n",
                        __FILE__, __LINE__, info->irq_level);

        spin_lock(&info->irq_spinlock);

        for(;;) {
                /* Read the interrupt vectors from hardware. */
                UscVector = usc_InReg(info, IVR) >> 9;
                DmaVector = usc_InDmaReg(info, DIVR);
                
                if ( debug_level >= DEBUG_LEVEL_ISR )   
                        printk("%s(%d):%s UscVector=%08X DmaVector=%08X\n",
                                __FILE__,__LINE__,info->device_name,UscVector,DmaVector);
                        
                if ( !UscVector && !DmaVector )
                        break;
                        
                /* Dispatch interrupt vector */
                if ( UscVector )
                        (*UscIsrTable[UscVector])(info);
                else if ( (DmaVector&(BIT10|BIT9)) == BIT10)
                        mgsl_isr_transmit_dma(info);
                else
                        mgsl_isr_receive_dma(info);

                if ( info->isr_overflow ) {
                        printk(KERN_ERR "%s(%d):%s isr overflow irq=%d\n",
                                __FILE__, __LINE__, info->device_name, info->irq_level);
                        usc_DisableMasterIrqBit(info);
                        usc_DisableDmaInterrupts(info,DICR_MASTER);
                        break;
                }
        }
        
        /* Request bottom half processing if there's something 
         * for it to do and the bh is not already running
         */

        if ( info->pending_bh && !info->bh_running && !info->bh_requested ) {
                if ( debug_level >= DEBUG_LEVEL_ISR )   
                        printk("%s(%d):%s queueing bh task.\n",
                                __FILE__,__LINE__,info->device_name);
                schedule_work(&info->task);
                info->bh_requested = true;
        }

        spin_unlock(&info->irq_spinlock);
        
        if ( debug_level >= DEBUG_LEVEL_ISR )   
                printk(KERN_DEBUG "%s(%d):mgsl_interrupt(%d)exit.\n",
                        __FILE__, __LINE__, info->irq_level);

        return IRQ_HANDLED;
}       /* end of mgsl_interrupt() */

/* startup()
 * 
 *      Initialize and start device.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        0 if success, otherwise error code
 */
static int startup(struct mgsl_struct * info)
{
        int retval = 0;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s(%d):mgsl_startup(%s)\n",__FILE__,__LINE__,info->device_name);

        if (tty_port_initialized(&info->port))
                return 0;

        if (!info->xmit_buf) {
                /* allocate a page of memory for a transmit buffer */
                info->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
                if (!info->xmit_buf) {
                        printk(KERN_ERR"%s(%d):%s can't allocate transmit buffer\n",
                                __FILE__,__LINE__,info->device_name);
                        return -ENOMEM;
                }
        }

        info->pending_bh = 0;
        
        memset(&info->icount, 0, sizeof(info->icount));

        timer_setup(&info->tx_timer, mgsl_tx_timeout, 0);
        
        /* Allocate and claim adapter resources */
        retval = mgsl_claim_resources(info);
        
        /* perform existence check and diagnostics */
        if ( !retval )
                retval = mgsl_adapter_test(info);
                
        if ( retval ) {
                if (capable(CAP_SYS_ADMIN) && info->port.tty)
                        set_bit(TTY_IO_ERROR, &info->port.tty->flags);
                mgsl_release_resources(info);
                return retval;
        }

        /* program hardware for current parameters */
        mgsl_change_params(info);

        if (info->port.tty)
                clear_bit(TTY_IO_ERROR, &info->port.tty->flags);

        tty_port_set_initialized(&info->port, 1);

        return 0;
}       /* end of startup() */

/* shutdown()
 *
 * Called by mgsl_close() and mgsl_hangup() to shutdown hardware
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void shutdown(struct mgsl_struct * info)
{
        unsigned long flags;

        if (!tty_port_initialized(&info->port))
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_shutdown(%s)\n",
                         __FILE__,__LINE__, info->device_name );

        /* clear status wait queue because status changes */
        /* can't happen after shutting down the hardware */
        wake_up_interruptible(&info->status_event_wait_q);
        wake_up_interruptible(&info->event_wait_q);

        del_timer_sync(&info->tx_timer);

        if (info->xmit_buf) {
                free_page((unsigned long) info->xmit_buf);
                info->xmit_buf = NULL;
        }

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_DisableMasterIrqBit(info);
        usc_stop_receiver(info);
        usc_stop_transmitter(info);
        usc_DisableInterrupts(info,RECEIVE_DATA | RECEIVE_STATUS |
                TRANSMIT_DATA | TRANSMIT_STATUS | IO_PIN | MISC );
        usc_DisableDmaInterrupts(info,DICR_MASTER + DICR_TRANSMIT + DICR_RECEIVE);

        /* Disable DMAEN (Port 7, Bit 14) */
        /* This disconnects the DMA request signal from the ISA bus */
        /* on the ISA adapter. This has no effect for the PCI adapter */
        usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT15) | BIT14));

        /* Disable INTEN (Port 6, Bit12) */
        /* This disconnects the IRQ request signal to the ISA bus */
        /* on the ISA adapter. This has no effect for the PCI adapter */
        usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT13) | BIT12));

        if (!info->port.tty || info->port.tty->termios.c_cflag & HUPCL) {
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
                usc_set_serial_signals(info);
        }

        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        mgsl_release_resources(info);

        if (info->port.tty)
                set_bit(TTY_IO_ERROR, &info->port.tty->flags);

        tty_port_set_initialized(&info->port, 0);
}       /* end of shutdown() */

static void mgsl_program_hw(struct mgsl_struct *info)
{
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        
        usc_stop_receiver(info);
        usc_stop_transmitter(info);
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        
        if (info->params.mode == MGSL_MODE_HDLC ||
            info->params.mode == MGSL_MODE_RAW ||
            info->netcount)
                usc_set_sync_mode(info);
        else
                usc_set_async_mode(info);
                
        usc_set_serial_signals(info);
        
        info->dcd_chkcount = 0;
        info->cts_chkcount = 0;
        info->ri_chkcount = 0;
        info->dsr_chkcount = 0;

        usc_EnableStatusIrqs(info,SICR_CTS+SICR_DSR+SICR_DCD+SICR_RI);
        usc_EnableInterrupts(info, IO_PIN);
        usc_get_serial_signals(info);
                
        if (info->netcount || info->port.tty->termios.c_cflag & CREAD)
                usc_start_receiver(info);
                
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}

/* Reconfigure adapter based on new parameters
 */
static void mgsl_change_params(struct mgsl_struct *info)
{
        unsigned cflag;
        int bits_per_char;

        if (!info->port.tty)
                return;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_change_params(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        cflag = info->port.tty->termios.c_cflag;

        /* if B0 rate (hangup) specified then negate RTS and DTR */
        /* otherwise assert RTS and DTR */
        if (cflag & CBAUD)
                info->serial_signals |= SerialSignal_RTS | SerialSignal_DTR;
        else
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
        
        /* byte size and parity */
        
        switch (cflag & CSIZE) {
              case CS5: info->params.data_bits = 5; break;
              case CS6: info->params.data_bits = 6; break;
              case CS7: info->params.data_bits = 7; break;
              case CS8: info->params.data_bits = 8; break;
              /* Never happens, but GCC is too dumb to figure it out */
              default:  info->params.data_bits = 7; break;
              }
              
        if (cflag & CSTOPB)
                info->params.stop_bits = 2;
        else
                info->params.stop_bits = 1;

        info->params.parity = ASYNC_PARITY_NONE;
        if (cflag & PARENB) {
                if (cflag & PARODD)
                        info->params.parity = ASYNC_PARITY_ODD;
                else
                        info->params.parity = ASYNC_PARITY_EVEN;
#ifdef CMSPAR
                if (cflag & CMSPAR)
                        info->params.parity = ASYNC_PARITY_SPACE;
#endif
        }

        /* calculate number of jiffies to transmit a full
         * FIFO (32 bytes) at specified data rate
         */
        bits_per_char = info->params.data_bits + 
                        info->params.stop_bits + 1;

        /* if port data rate is set to 460800 or less then
         * allow tty settings to override, otherwise keep the
         * current data rate.
         */
        if (info->params.data_rate <= 460800)
                info->params.data_rate = tty_get_baud_rate(info->port.tty);
        
        if ( info->params.data_rate ) {
                info->timeout = (32*HZ*bits_per_char) / 
                                info->params.data_rate;
        }
        info->timeout += HZ/50;         /* Add .02 seconds of slop */

        tty_port_set_cts_flow(&info->port, cflag & CRTSCTS);
        tty_port_set_check_carrier(&info->port, ~cflag & CLOCAL);

        /* process tty input control flags */
        
        info->read_status_mask = RXSTATUS_OVERRUN;
        if (I_INPCK(info->port.tty))
                info->read_status_mask |= RXSTATUS_PARITY_ERROR | RXSTATUS_FRAMING_ERROR;
        if (I_BRKINT(info->port.tty) || I_PARMRK(info->port.tty))
                info->read_status_mask |= RXSTATUS_BREAK_RECEIVED;
        
        if (I_IGNPAR(info->port.tty))
                info->ignore_status_mask |= RXSTATUS_PARITY_ERROR | RXSTATUS_FRAMING_ERROR;
        if (I_IGNBRK(info->port.tty)) {
                info->ignore_status_mask |= RXSTATUS_BREAK_RECEIVED;
                /* If ignoring parity and break indicators, ignore 
                 * overruns too.  (For real raw support).
                 */
                if (I_IGNPAR(info->port.tty))
                        info->ignore_status_mask |= RXSTATUS_OVERRUN;
        }

        mgsl_program_hw(info);

}       /* end of mgsl_change_params() */

/* mgsl_put_char()
 * 
 *      Add a character to the transmit buffer.
 *      
 * Arguments:           tty     pointer to tty information structure
 *                      ch      character to add to transmit buffer
 *              
 * Return Value:        None
 */
static int mgsl_put_char(struct tty_struct *tty, unsigned char ch)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        int ret = 0;

        if (debug_level >= DEBUG_LEVEL_INFO) {
                printk(KERN_DEBUG "%s(%d):mgsl_put_char(%d) on %s\n",
                        __FILE__, __LINE__, ch, info->device_name);
        }               
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_put_char"))
                return 0;

        if (!info->xmit_buf)
                return 0;

        spin_lock_irqsave(&info->irq_spinlock, flags);
        
        if ((info->params.mode == MGSL_MODE_ASYNC ) || !info->tx_active) {
                if (info->xmit_cnt < SERIAL_XMIT_SIZE - 1) {
                        info->xmit_buf[info->xmit_head++] = ch;
                        info->xmit_head &= SERIAL_XMIT_SIZE-1;
                        info->xmit_cnt++;
                        ret = 1;
                }
        }
        spin_unlock_irqrestore(&info->irq_spinlock, flags);
        return ret;
        
}       /* end of mgsl_put_char() */

/* mgsl_flush_chars()
 * 
 *      Enable transmitter so remaining characters in the
 *      transmit buffer are sent.
 *      
 * Arguments:           tty     pointer to tty information structure
 * Return Value:        None
 */
static void mgsl_flush_chars(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
                                
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_flush_chars() entry on %s xmit_cnt=%d\n",
                        __FILE__,__LINE__,info->device_name,info->xmit_cnt);
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_flush_chars"))
                return;

        if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
            !info->xmit_buf)
                return;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_flush_chars() entry on %s starting transmitter\n",
                        __FILE__,__LINE__,info->device_name );

        spin_lock_irqsave(&info->irq_spinlock,flags);
        
        if (!info->tx_active) {
                if ( (info->params.mode == MGSL_MODE_HDLC ||
                        info->params.mode == MGSL_MODE_RAW) && info->xmit_cnt ) {
                        /* operating in synchronous (frame oriented) mode */
                        /* copy data from circular xmit_buf to */
                        /* transmit DMA buffer. */
                        mgsl_load_tx_dma_buffer(info,
                                 info->xmit_buf,info->xmit_cnt);
                }
                usc_start_transmitter(info);
        }
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
}       /* end of mgsl_flush_chars() */

/* mgsl_write()
 * 
 *      Send a block of data
 *      
 * Arguments:
 * 
 *      tty             pointer to tty information structure
 *      buf             pointer to buffer containing send data
 *      count           size of send data in bytes
 *      
 * Return Value:        number of characters written
 */
static int mgsl_write(struct tty_struct * tty,
                    const unsigned char *buf, int count)
{
        int     c, ret = 0;
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_write(%s) count=%d\n",
                        __FILE__,__LINE__,info->device_name,count);
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_write"))
                goto cleanup;

        if (!info->xmit_buf)
                goto cleanup;

        if ( info->params.mode == MGSL_MODE_HDLC ||
                        info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if (info->tx_active) {

                        if ( info->params.mode == MGSL_MODE_HDLC ) {
                                ret = 0;
                                goto cleanup;
                        }
                        /* transmitter is actively sending data -
                         * if we have multiple transmit dma and
                         * holding buffers, attempt to queue this
                         * frame for transmission at a later time.
                         */
                        if (info->tx_holding_count >= info->num_tx_holding_buffers ) {
                                /* no tx holding buffers available */
                                ret = 0;
                                goto cleanup;
                        }

                        /* queue transmit frame request */
                        ret = count;
                        save_tx_buffer_request(info,buf,count);

                        /* if we have sufficient tx dma buffers,
                         * load the next buffered tx request
                         */
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        load_next_tx_holding_buffer(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        goto cleanup;
                }
        
                /* if operating in HDLC LoopMode and the adapter  */
                /* has yet to be inserted into the loop, we can't */
                /* transmit                                       */

                if ( (info->params.flags & HDLC_FLAG_HDLC_LOOPMODE) &&
                        !usc_loopmode_active(info) )
                {
                        ret = 0;
                        goto cleanup;
                }

                if ( info->xmit_cnt ) {
                        /* Send accumulated from send_char() calls */
                        /* as frame and wait before accepting more data. */
                        ret = 0;
                        
                        /* copy data from circular xmit_buf to */
                        /* transmit DMA buffer. */
                        mgsl_load_tx_dma_buffer(info,
                                info->xmit_buf,info->xmit_cnt);
                        if ( debug_level >= DEBUG_LEVEL_INFO )
                                printk( "%s(%d):mgsl_write(%s) sync xmit_cnt flushing\n",
                                        __FILE__,__LINE__,info->device_name);
                } else {
                        if ( debug_level >= DEBUG_LEVEL_INFO )
                                printk( "%s(%d):mgsl_write(%s) sync transmit accepted\n",
                                        __FILE__,__LINE__,info->device_name);
                        ret = count;
                        info->xmit_cnt = count;
                        mgsl_load_tx_dma_buffer(info,buf,count);
                }
        } else {
                while (1) {
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        c = min_t(int, count,
                                min(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
                                    SERIAL_XMIT_SIZE - info->xmit_head));
                        if (c <= 0) {
                                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                                break;
                        }
                        memcpy(info->xmit_buf + info->xmit_head, buf, c);
                        info->xmit_head = ((info->xmit_head + c) &
                                           (SERIAL_XMIT_SIZE-1));
                        info->xmit_cnt += c;
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        buf += c;
                        count -= c;
                        ret += c;
                }
        }       
        
        if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!info->tx_active)
                        usc_start_transmitter(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
cleanup:        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_write(%s) returning=%d\n",
                        __FILE__,__LINE__,info->device_name,ret);
                        
        return ret;
        
}       /* end of mgsl_write() */

/* mgsl_write_room()
 *
 *      Return the count of free bytes in transmit buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static int mgsl_write_room(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        int     ret;
                                
        if (mgsl_paranoia_check(info, tty->name, "mgsl_write_room"))
                return 0;
        ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
        if (ret < 0)
                ret = 0;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_write_room(%s)=%d\n",
                         __FILE__,__LINE__, info->device_name,ret );
                         
        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if ( info->tx_active )
                        return 0;
                else
                        return HDLC_MAX_FRAME_SIZE;
        }
        
        return ret;
        
}       /* end of mgsl_write_room() */

/* mgsl_chars_in_buffer()
 *
 *      Return the count of bytes in transmit buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static int mgsl_chars_in_buffer(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
                         
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_chars_in_buffer(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_chars_in_buffer"))
                return 0;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_chars_in_buffer(%s)=%d\n",
                         __FILE__,__LINE__, info->device_name,info->xmit_cnt );
                         
        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                /* operating in synchronous (frame oriented) mode */
                if ( info->tx_active )
                        return info->max_frame_size;
                else
                        return 0;
        }
                         
        return info->xmit_cnt;
}       /* end of mgsl_chars_in_buffer() */

/* mgsl_flush_buffer()
 *
 *      Discard all data in the send buffer
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_flush_buffer(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_flush_buffer(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_flush_buffer"))
                return;
                
        spin_lock_irqsave(&info->irq_spinlock,flags); 
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        del_timer(&info->tx_timer);     
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        tty_wakeup(tty);
}

/* mgsl_send_xchar()
 *
 *      Send a high-priority XON/XOFF character
 *      
 * Arguments:           tty     pointer to tty info structure
 *                      ch      character to send
 * Return Value:        None
 */
static void mgsl_send_xchar(struct tty_struct *tty, char ch)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_send_xchar(%s,%d)\n",
                         __FILE__,__LINE__, info->device_name, ch );
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_send_xchar"))
                return;

        info->x_char = ch;
        if (ch) {
                /* Make sure transmit interrupts are on */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!info->tx_enabled)
                        usc_start_transmitter(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
}       /* end of mgsl_send_xchar() */

/* mgsl_throttle()
 * 
 *      Signal remote device to throttle send data (our receive data)
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_throttle(struct tty_struct * tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_throttle(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (mgsl_paranoia_check(info, tty->name, "mgsl_throttle"))
                return;
        
        if (I_IXOFF(tty))
                mgsl_send_xchar(tty, STOP_CHAR(tty));

        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                info->serial_signals &= ~SerialSignal_RTS;
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
}       /* end of mgsl_throttle() */

/* mgsl_unthrottle()
 * 
 *      Signal remote device to stop throttling send data (our receive data)
 *      
 * Arguments:           tty     pointer to tty info structure
 * Return Value:        None
 */
static void mgsl_unthrottle(struct tty_struct * tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_unthrottle(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (mgsl_paranoia_check(info, tty->name, "mgsl_unthrottle"))
                return;
        
        if (I_IXOFF(tty)) {
                if (info->x_char)
                        info->x_char = 0;
                else
                        mgsl_send_xchar(tty, START_CHAR(tty));
        }

        if (C_CRTSCTS(tty)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                info->serial_signals |= SerialSignal_RTS;
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
        
}       /* end of mgsl_unthrottle() */

/* mgsl_get_stats()
 * 
 *      get the current serial parameters information
 *
 * Arguments:   info            pointer to device instance data
 *              user_icount     pointer to buffer to hold returned stats
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_stats(struct mgsl_struct * info, struct mgsl_icount __user *user_icount)
{
        int err;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_params(%s)\n",
                         __FILE__,__LINE__, info->device_name);
                        
        if (!user_icount) {
                memset(&info->icount, 0, sizeof(info->icount));
        } else {
                mutex_lock(&info->port.mutex);
                COPY_TO_USER(err, user_icount, &info->icount, sizeof(struct mgsl_icount));
                mutex_unlock(&info->port.mutex);
                if (err)
                        return -EFAULT;
        }
        
        return 0;
        
}       /* end of mgsl_get_stats() */

/* mgsl_get_params()
 * 
 *      get the current serial parameters information
 *
 * Arguments:   info            pointer to device instance data
 *              user_params     pointer to buffer to hold returned params
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_params(struct mgsl_struct * info, MGSL_PARAMS __user *user_params)
{
        int err;
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_params(%s)\n",
                         __FILE__,__LINE__, info->device_name);
                        
        mutex_lock(&info->port.mutex);
        COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
        mutex_unlock(&info->port.mutex);
        if (err) {
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk( "%s(%d):mgsl_get_params(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        return 0;
        
}       /* end of mgsl_get_params() */

/* mgsl_set_params()
 * 
 *      set the serial parameters
 *      
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      new_params      user buffer containing new serial params
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_set_params(struct mgsl_struct * info, MGSL_PARAMS __user *new_params)
{
        unsigned long flags;
        MGSL_PARAMS tmp_params;
        int err;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_set_params %s\n", __FILE__,__LINE__,
                        info->device_name );
        COPY_FROM_USER(err,&tmp_params, new_params, sizeof(MGSL_PARAMS));
        if (err) {
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk( "%s(%d):mgsl_set_params(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        mutex_lock(&info->port.mutex);
        spin_lock_irqsave(&info->irq_spinlock,flags);
        memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        mgsl_change_params(info);
        mutex_unlock(&info->port.mutex);
        
        return 0;
        
}       /* end of mgsl_set_params() */

/* mgsl_get_txidle()
 * 
 *      get the current transmit idle mode
 *
 * Arguments:   info            pointer to device instance data
 *              idle_mode       pointer to buffer to hold returned idle mode
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_get_txidle(struct mgsl_struct * info, int __user *idle_mode)
{
        int err;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_get_txidle(%s)=%d\n",
                         __FILE__,__LINE__, info->device_name, info->idle_mode);
                        
        COPY_TO_USER(err,idle_mode, &info->idle_mode, sizeof(int));
        if (err) {
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk( "%s(%d):mgsl_get_txidle(%s) user buffer copy failed\n",
                                __FILE__,__LINE__,info->device_name);
                return -EFAULT;
        }
        
        return 0;
        
}       /* end of mgsl_get_txidle() */

/* mgsl_set_txidle()    service ioctl to set transmit idle mode
 *      
 * Arguments:           info            pointer to device instance data
 *                      idle_mode       new idle mode
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_set_txidle(struct mgsl_struct * info, int idle_mode)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_set_txidle(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, idle_mode );
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        info->idle_mode = idle_mode;
        usc_set_txidle( info );
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_set_txidle() */

/* mgsl_txenable()
 * 
 *      enable or disable the transmitter
 *      
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      enable          1 = enable, 0 = disable
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_txenable(struct mgsl_struct * info, int enable)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_txenable(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, enable);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( enable ) {
                if ( !info->tx_enabled ) {

                        usc_start_transmitter(info);
                        /*--------------------------------------------------
                         * if HDLC/SDLC Loop mode, attempt to insert the
                         * station in the 'loop' by setting CMR:13. Upon
                         * receipt of the next GoAhead (RxAbort) sequence,
                         * the OnLoop indicator (CCSR:7) should go active
                         * to indicate that we are on the loop
                         *--------------------------------------------------*/
                        if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
                                usc_loopmode_insert_request( info );
                }
        } else {
                if ( info->tx_enabled )
                        usc_stop_transmitter(info);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_txenable() */

/* mgsl_txabort()       abort send HDLC frame
 *      
 * Arguments:           info            pointer to device instance data
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_txabort(struct mgsl_struct * info)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_txabort(%s)\n", __FILE__,__LINE__,
                        info->device_name);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( info->tx_active && info->params.mode == MGSL_MODE_HDLC )
        {
                if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
                        usc_loopmode_cancel_transmit( info );
                else
                        usc_TCmd(info,TCmd_SendAbort);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_txabort() */

/* mgsl_rxenable()      enable or disable the receiver
 *      
 * Arguments:           info            pointer to device instance data
 *                      enable          1 = enable, 0 = disable
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_rxenable(struct mgsl_struct * info, int enable)
{
        unsigned long flags;
 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_rxenable(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, enable);
                        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if ( enable ) {
                if ( !info->rx_enabled )
                        usc_start_receiver(info);
        } else {
                if ( info->rx_enabled )
                        usc_stop_receiver(info);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_rxenable() */

/* mgsl_wait_event()    wait for specified event to occur
 *      
 * Arguments:           info    pointer to device instance data
 *                      mask    pointer to bitmask of events to wait for
 * Return Value:        0       if successful and bit mask updated with
 *                              of events triggerred,
 *                      otherwise error code
 */
static int mgsl_wait_event(struct mgsl_struct * info, int __user * mask_ptr)
{
        unsigned long flags;
        int s;
        int rc=0;
        struct mgsl_icount cprev, cnow;
        int events;
        int mask;
        struct  _input_signal_events oldsigs, newsigs;
        DECLARE_WAITQUEUE(wait, current);

        COPY_FROM_USER(rc,&mask, mask_ptr, sizeof(int));
        if (rc) {
                return  -EFAULT;
        }
                 
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_wait_event(%s,%d)\n", __FILE__,__LINE__,
                        info->device_name, mask);

        spin_lock_irqsave(&info->irq_spinlock,flags);

        /* return immediately if state matches requested events */
        usc_get_serial_signals(info);
        s = info->serial_signals;
        events = mask &
                ( ((s & SerialSignal_DSR) ? MgslEvent_DsrActive:MgslEvent_DsrInactive) +
                  ((s & SerialSignal_DCD) ? MgslEvent_DcdActive:MgslEvent_DcdInactive) +
                  ((s & SerialSignal_CTS) ? MgslEvent_CtsActive:MgslEvent_CtsInactive) +
                  ((s & SerialSignal_RI)  ? MgslEvent_RiActive :MgslEvent_RiInactive) );
        if (events) {
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                goto exit;
        }

        /* save current irq counts */
        cprev = info->icount;
        oldsigs = info->input_signal_events;
        
        /* enable hunt and idle irqs if needed */
        if (mask & (MgslEvent_ExitHuntMode + MgslEvent_IdleReceived)) {
                u16 oldreg = usc_InReg(info,RICR);
                u16 newreg = oldreg +
                         (mask & MgslEvent_ExitHuntMode ? RXSTATUS_EXITED_HUNT:0) +
                         (mask & MgslEvent_IdleReceived ? RXSTATUS_IDLE_RECEIVED:0);
                if (oldreg != newreg)
                        usc_OutReg(info, RICR, newreg);
        }
        
        set_current_state(TASK_INTERRUPTIBLE);
        add_wait_queue(&info->event_wait_q, &wait);
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        

        for(;;) {
                schedule();
                if (signal_pending(current)) {
                        rc = -ERESTARTSYS;
                        break;
                }
                        
                /* get current irq counts */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                cnow = info->icount;
                newsigs = info->input_signal_events;
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                /* if no change, wait aborted for some reason */
                if (newsigs.dsr_up   == oldsigs.dsr_up   &&
                    newsigs.dsr_down == oldsigs.dsr_down &&
                    newsigs.dcd_up   == oldsigs.dcd_up   &&
                    newsigs.dcd_down == oldsigs.dcd_down &&
                    newsigs.cts_up   == oldsigs.cts_up   &&
                    newsigs.cts_down == oldsigs.cts_down &&
                    newsigs.ri_up    == oldsigs.ri_up    &&
                    newsigs.ri_down  == oldsigs.ri_down  &&
                    cnow.exithunt    == cprev.exithunt   &&
                    cnow.rxidle      == cprev.rxidle) {
                        rc = -EIO;
                        break;
                }

                events = mask &
                        ( (newsigs.dsr_up   != oldsigs.dsr_up   ? MgslEvent_DsrActive:0)   +
                        (newsigs.dsr_down != oldsigs.dsr_down ? MgslEvent_DsrInactive:0) +
                        (newsigs.dcd_up   != oldsigs.dcd_up   ? MgslEvent_DcdActive:0)   +
                        (newsigs.dcd_down != oldsigs.dcd_down ? MgslEvent_DcdInactive:0) +
                        (newsigs.cts_up   != oldsigs.cts_up   ? MgslEvent_CtsActive:0)   +
                        (newsigs.cts_down != oldsigs.cts_down ? MgslEvent_CtsInactive:0) +
                        (newsigs.ri_up    != oldsigs.ri_up    ? MgslEvent_RiActive:0)    +
                        (newsigs.ri_down  != oldsigs.ri_down  ? MgslEvent_RiInactive:0)  +
                        (cnow.exithunt    != cprev.exithunt   ? MgslEvent_ExitHuntMode:0) +
                          (cnow.rxidle      != cprev.rxidle     ? MgslEvent_IdleReceived:0) );
                if (events)
                        break;
                
                cprev = cnow;
                oldsigs = newsigs;
        }
        
        remove_wait_queue(&info->event_wait_q, &wait);
        set_current_state(TASK_RUNNING);

        if (mask & (MgslEvent_ExitHuntMode + MgslEvent_IdleReceived)) {
                spin_lock_irqsave(&info->irq_spinlock,flags);
                if (!waitqueue_active(&info->event_wait_q)) {
                        /* disable enable exit hunt mode/idle rcvd IRQs */
                        usc_OutReg(info, RICR, usc_InReg(info,RICR) &
                                ~(RXSTATUS_EXITED_HUNT | RXSTATUS_IDLE_RECEIVED));
                }
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }
exit:
        if ( rc == 0 )
                PUT_USER(rc, events, mask_ptr);
                
        return rc;
        
}       /* end of mgsl_wait_event() */

static int modem_input_wait(struct mgsl_struct *info,int arg)
{
        unsigned long flags;
        int rc;
        struct mgsl_icount cprev, cnow;
        DECLARE_WAITQUEUE(wait, current);

        /* save current irq counts */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        cprev = info->icount;
        add_wait_queue(&info->status_event_wait_q, &wait);
        set_current_state(TASK_INTERRUPTIBLE);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        for(;;) {
                schedule();
                if (signal_pending(current)) {
                        rc = -ERESTARTSYS;
                        break;
                }

                /* get new irq counts */
                spin_lock_irqsave(&info->irq_spinlock,flags);
                cnow = info->icount;
                set_current_state(TASK_INTERRUPTIBLE);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                /* if no change, wait aborted for some reason */
                if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
                    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
                        rc = -EIO;
                        break;
                }

                /* check for change in caller specified modem input */
                if ((arg & TIOCM_RNG && cnow.rng != cprev.rng) ||
                    (arg & TIOCM_DSR && cnow.dsr != cprev.dsr) ||
                    (arg & TIOCM_CD  && cnow.dcd != cprev.dcd) ||
                    (arg & TIOCM_CTS && cnow.cts != cprev.cts)) {
                        rc = 0;
                        break;
                }

                cprev = cnow;
        }
        remove_wait_queue(&info->status_event_wait_q, &wait);
        set_current_state(TASK_RUNNING);
        return rc;
}

/* return the state of the serial control and status signals
 */
static int tiocmget(struct tty_struct *tty)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned int result;
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_get_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        result = ((info->serial_signals & SerialSignal_RTS) ? TIOCM_RTS:0) +
                ((info->serial_signals & SerialSignal_DTR) ? TIOCM_DTR:0) +
                ((info->serial_signals & SerialSignal_DCD) ? TIOCM_CAR:0) +
                ((info->serial_signals & SerialSignal_RI)  ? TIOCM_RNG:0) +
                ((info->serial_signals & SerialSignal_DSR) ? TIOCM_DSR:0) +
                ((info->serial_signals & SerialSignal_CTS) ? TIOCM_CTS:0);

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s tiocmget() value=%08X\n",
                         __FILE__,__LINE__, info->device_name, result );
        return result;
}

/* set modem control signals (DTR/RTS)
 */
static int tiocmset(struct tty_struct *tty,
                                    unsigned int set, unsigned int clear)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):%s tiocmset(%x,%x)\n",
                        __FILE__,__LINE__,info->device_name, set, clear);

        if (set & TIOCM_RTS)
                info->serial_signals |= SerialSignal_RTS;
        if (set & TIOCM_DTR)
                info->serial_signals |= SerialSignal_DTR;
        if (clear & TIOCM_RTS)
                info->serial_signals &= ~SerialSignal_RTS;
        if (clear & TIOCM_DTR)
                info->serial_signals &= ~SerialSignal_DTR;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_set_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        return 0;
}

/* mgsl_break()         Set or clear transmit break condition
 *
 * Arguments:           tty             pointer to tty instance data
 *                      break_state     -1=set break condition, 0=clear
 * Return Value:        error code
 */
static int mgsl_break(struct tty_struct *tty, int break_state)
{
        struct mgsl_struct * info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_break(%s,%d)\n",
                         __FILE__,__LINE__, info->device_name, break_state);
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_break"))
                return -EINVAL;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (break_state == -1)
                usc_OutReg(info,IOCR,(u16)(usc_InReg(info,IOCR) | BIT7));
        else 
                usc_OutReg(info,IOCR,(u16)(usc_InReg(info,IOCR) & ~BIT7));
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        return 0;
        
}       /* end of mgsl_break() */

/*
 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
 * Return: write counters to the user passed counter struct
 * NB: both 1->0 and 0->1 transitions are counted except for
 *     RI where only 0->1 is counted.
 */
static int msgl_get_icount(struct tty_struct *tty,
                                struct serial_icounter_struct *icount)

{
        struct mgsl_struct * info = tty->driver_data;
        struct mgsl_icount cnow;        /* kernel counter temps */
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        cnow = info->icount;
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        icount->cts = cnow.cts;
        icount->dsr = cnow.dsr;
        icount->rng = cnow.rng;
        icount->dcd = cnow.dcd;
        icount->rx = cnow.rx;
        icount->tx = cnow.tx;
        icount->frame = cnow.frame;
        icount->overrun = cnow.overrun;
        icount->parity = cnow.parity;
        icount->brk = cnow.brk;
        icount->buf_overrun = cnow.buf_overrun;
        return 0;
}

/* mgsl_ioctl() Service an IOCTL request
 *      
 * Arguments:
 * 
 *      tty     pointer to tty instance data
 *      cmd     IOCTL command code
 *      arg     command argument/context
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_ioctl(struct tty_struct *tty,
                    unsigned int cmd, unsigned long arg)
{
        struct mgsl_struct * info = tty->driver_data;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_ioctl %s cmd=%08X\n", __FILE__,__LINE__,
                        info->device_name, cmd );
        
        if (mgsl_paranoia_check(info, tty->name, "mgsl_ioctl"))
                return -ENODEV;

        if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
            (cmd != TIOCMIWAIT)) {
                if (tty_io_error(tty))
                    return -EIO;
        }

        return mgsl_ioctl_common(info, cmd, arg);
}

static int mgsl_ioctl_common(struct mgsl_struct *info, unsigned int cmd, unsigned long arg)
{
        void __user *argp = (void __user *)arg;
        
        switch (cmd) {
                case MGSL_IOCGPARAMS:
                        return mgsl_get_params(info, argp);
                case MGSL_IOCSPARAMS:
                        return mgsl_set_params(info, argp);
                case MGSL_IOCGTXIDLE:
                        return mgsl_get_txidle(info, argp);
                case MGSL_IOCSTXIDLE:
                        return mgsl_set_txidle(info,(int)arg);
                case MGSL_IOCTXENABLE:
                        return mgsl_txenable(info,(int)arg);
                case MGSL_IOCRXENABLE:
                        return mgsl_rxenable(info,(int)arg);
                case MGSL_IOCTXABORT:
                        return mgsl_txabort(info);
                case MGSL_IOCGSTATS:
                        return mgsl_get_stats(info, argp);
                case MGSL_IOCWAITEVENT:
                        return mgsl_wait_event(info, argp);
                case MGSL_IOCLOOPTXDONE:
                        return mgsl_loopmode_send_done(info);
                /* Wait for modem input (DCD,RI,DSR,CTS) change
                 * as specified by mask in arg (TIOCM_RNG/DSR/CD/CTS)
                 */
                case TIOCMIWAIT:
                        return modem_input_wait(info,(int)arg);

                default:
                        return -ENOIOCTLCMD;
        }
        return 0;
}

/* mgsl_set_termios()
 * 
 *      Set new termios settings
 *      
 * Arguments:
 * 
 *      tty             pointer to tty structure
 *      termios         pointer to buffer to hold returned old termios
 *      
 * Return Value:                None
 */
static void mgsl_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_set_termios %s\n", __FILE__,__LINE__,
                        tty->driver->name );
        
        mgsl_change_params(info);

        /* Handle transition to B0 status */
        if ((old_termios->c_cflag & CBAUD) && !C_BAUD(tty)) {
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
                spin_lock_irqsave(&info->irq_spinlock,flags);
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }

        /* Handle transition away from B0 status */
        if (!(old_termios->c_cflag & CBAUD) && C_BAUD(tty)) {
                info->serial_signals |= SerialSignal_DTR;
                if (!C_CRTSCTS(tty) || !tty_throttled(tty))
                        info->serial_signals |= SerialSignal_RTS;
                spin_lock_irqsave(&info->irq_spinlock,flags);
                usc_set_serial_signals(info);
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
        }

        /* Handle turning off CRTSCTS */
        if (old_termios->c_cflag & CRTSCTS && !C_CRTSCTS(tty)) {
                tty->hw_stopped = 0;
                mgsl_start(tty);
        }

}       /* end of mgsl_set_termios() */

/* mgsl_close()
 * 
 *      Called when port is closed. Wait for remaining data to be
 *      sent. Disable port and free resources.
 *      
 * Arguments:
 * 
 *      tty     pointer to open tty structure
 *      filp    pointer to open file object
 *      
 * Return Value:        None
 */
static void mgsl_close(struct tty_struct *tty, struct file * filp)
{
        struct mgsl_struct * info = tty->driver_data;

        if (mgsl_paranoia_check(info, tty->name, "mgsl_close"))
                return;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_close(%s) entry, count=%d\n",
                         __FILE__,__LINE__, info->device_name, info->port.count);

        if (tty_port_close_start(&info->port, tty, filp) == 0)
                goto cleanup;

        mutex_lock(&info->port.mutex);
        if (tty_port_initialized(&info->port))
                mgsl_wait_until_sent(tty, info->timeout);
        mgsl_flush_buffer(tty);
        tty_ldisc_flush(tty);
        shutdown(info);
        mutex_unlock(&info->port.mutex);

        tty_port_close_end(&info->port, tty);   
        info->port.tty = NULL;
cleanup:                        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_close(%s) exit, count=%d\n", __FILE__,__LINE__,
                        tty->driver->name, info->port.count);
                        
}       /* end of mgsl_close() */

/* mgsl_wait_until_sent()
 *
 *      Wait until the transmitter is empty.
 *
 * Arguments:
 *
 *      tty             pointer to tty info structure
 *      timeout         time to wait for send completion
 *
 * Return Value:        None
 */
static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout)
{
        struct mgsl_struct * info = tty->driver_data;
        unsigned long orig_jiffies, char_time;

        if (!info )
                return;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_wait_until_sent(%s) entry\n",
                         __FILE__,__LINE__, info->device_name );

        if (mgsl_paranoia_check(info, tty->name, "mgsl_wait_until_sent"))
                return;

        if (!tty_port_initialized(&info->port))
                goto exit;

        orig_jiffies = jiffies;

        /* Set check interval to 1/5 of estimated time to
         * send a character, and make it at least 1. The check
         * interval should also be less than the timeout.
         * Note: use tight timings here to satisfy the NIST-PCTS.
         */ 

        if ( info->params.data_rate ) {
                char_time = info->timeout/(32 * 5);
                if (!char_time)
                        char_time++;
        } else
                char_time = 1;
                
        if (timeout)
                char_time = min_t(unsigned long, char_time, timeout);
                
        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                while (info->tx_active) {
                        msleep_interruptible(jiffies_to_msecs(char_time));
                        if (signal_pending(current))
                                break;
                        if (timeout && time_after(jiffies, orig_jiffies + timeout))
                                break;
                }
        } else {
                while (!(usc_InReg(info,TCSR) & TXSTATUS_ALL_SENT) &&
                        info->tx_enabled) {
                        msleep_interruptible(jiffies_to_msecs(char_time));
                        if (signal_pending(current))
                                break;
                        if (timeout && time_after(jiffies, orig_jiffies + timeout))
                                break;
                }
        }
      
exit:
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_wait_until_sent(%s) exit\n",
                         __FILE__,__LINE__, info->device_name );
                         
}       /* end of mgsl_wait_until_sent() */

/* mgsl_hangup()
 *
 *      Called by tty_hangup() when a hangup is signaled.
 *      This is the same as to closing all open files for the port.
 *
 * Arguments:           tty     pointer to associated tty object
 * Return Value:        None
 */
static void mgsl_hangup(struct tty_struct *tty)
{
        struct mgsl_struct * info = tty->driver_data;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_hangup(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        if (mgsl_paranoia_check(info, tty->name, "mgsl_hangup"))
                return;

        mgsl_flush_buffer(tty);
        shutdown(info);
        
        info->port.count = 0;   
        tty_port_set_active(&info->port, 0);
        info->port.tty = NULL;

        wake_up_interruptible(&info->port.open_wait);
        
}       /* end of mgsl_hangup() */

/*
 * carrier_raised()
 *
 *      Return true if carrier is raised
 */

static int carrier_raised(struct tty_port *port)
{
        unsigned long flags;
        struct mgsl_struct *info = container_of(port, struct mgsl_struct, port);
        
        spin_lock_irqsave(&info->irq_spinlock, flags);
        usc_get_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock, flags);
        return (info->serial_signals & SerialSignal_DCD) ? 1 : 0;
}

static void dtr_rts(struct tty_port *port, int on)
{
        struct mgsl_struct *info = container_of(port, struct mgsl_struct, port);
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (on)
                info->serial_signals |= SerialSignal_RTS | SerialSignal_DTR;
        else
                info->serial_signals &= ~(SerialSignal_RTS | SerialSignal_DTR);
        usc_set_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}


/* block_til_ready()
 * 
 *      Block the current process until the specified port
 *      is ready to be opened.
 *      
 * Arguments:
 * 
 *      tty             pointer to tty info structure
 *      filp            pointer to open file object
 *      info            pointer to device instance data
 *      
 * Return Value:        0 if success, otherwise error code
 */
static int block_til_ready(struct tty_struct *tty, struct file * filp,
                           struct mgsl_struct *info)
{
        DECLARE_WAITQUEUE(wait, current);
        int             retval;
        bool            do_clocal = false;
        unsigned long   flags;
        int             dcd;
        struct tty_port *port = &info->port;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):block_til_ready on %s\n",
                         __FILE__,__LINE__, tty->driver->name );

        if (filp->f_flags & O_NONBLOCK || tty_io_error(tty)) {
                /* nonblock mode is set or port is not enabled */
                tty_port_set_active(port, 1);
                return 0;
        }

        if (C_CLOCAL(tty))
                do_clocal = true;

        /* Wait for carrier detect and the line to become
         * free (i.e., not in use by the callout).  While we are in
         * this loop, port->count is dropped by one, so that
         * mgsl_close() knows when to free things.  We restore it upon
         * exit, either normal or abnormal.
         */
         
        retval = 0;
        add_wait_queue(&port->open_wait, &wait);
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):block_til_ready before block on %s count=%d\n",
                         __FILE__,__LINE__, tty->driver->name, port->count );

        spin_lock_irqsave(&info->irq_spinlock, flags);
        port->count--;
        spin_unlock_irqrestore(&info->irq_spinlock, flags);
        port->blocked_open++;

        while (1) {
                if (C_BAUD(tty) && tty_port_initialized(port))
                        tty_port_raise_dtr_rts(port);

                set_current_state(TASK_INTERRUPTIBLE);

                if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
                        retval = (port->flags & ASYNC_HUP_NOTIFY) ?
                                        -EAGAIN : -ERESTARTSYS;
                        break;
                }

                dcd = tty_port_carrier_raised(&info->port);
                if (do_clocal || dcd)
                        break;

                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        break;
                }
                
                if (debug_level >= DEBUG_LEVEL_INFO)
                        printk("%s(%d):block_til_ready blocking on %s count=%d\n",
                                 __FILE__,__LINE__, tty->driver->name, port->count );
                                 
                tty_unlock(tty);
                schedule();
                tty_lock(tty);
        }
        
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&port->open_wait, &wait);
        
        /* FIXME: Racy on hangup during close wait */
        if (!tty_hung_up_p(filp))
                port->count++;
        port->blocked_open--;
        
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):block_til_ready after blocking on %s count=%d\n",
                         __FILE__,__LINE__, tty->driver->name, port->count );
                         
        if (!retval)
                tty_port_set_active(port, 1);
                
        return retval;
        
}       /* end of block_til_ready() */

static int mgsl_install(struct tty_driver *driver, struct tty_struct *tty)
{
        struct mgsl_struct *info;
        int line = tty->index;

        /* verify range of specified line number */
        if (line >= mgsl_device_count) {
                printk("%s(%d):mgsl_open with invalid line #%d.\n",
                        __FILE__, __LINE__, line);
                return -ENODEV;
        }

        /* find the info structure for the specified line */
        info = mgsl_device_list;
        while (info && info->line != line)
                info = info->next_device;
        if (mgsl_paranoia_check(info, tty->name, "mgsl_open"))
                return -ENODEV;
        tty->driver_data = info;

        return tty_port_install(&info->port, driver, tty);
}

/* mgsl_open()
 *
 *      Called when a port is opened.  Init and enable port.
 *      Perform serial-specific initialization for the tty structure.
 *
 * Arguments:           tty     pointer to tty info structure
 *                      filp    associated file pointer
 *
 * Return Value:        0 if success, otherwise error code
 */
static int mgsl_open(struct tty_struct *tty, struct file * filp)
{
        struct mgsl_struct *info = tty->driver_data;
        unsigned long flags;
        int retval;

        info->port.tty = tty;
                
        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_open(%s), old ref count = %d\n",
                         __FILE__,__LINE__,tty->driver->name, info->port.count);

        info->port.low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;

        spin_lock_irqsave(&info->netlock, flags);
        if (info->netcount) {
                retval = -EBUSY;
                spin_unlock_irqrestore(&info->netlock, flags);
                goto cleanup;
        }
        info->port.count++;
        spin_unlock_irqrestore(&info->netlock, flags);

        if (info->port.count == 1) {
                /* 1st open on this device, init hardware */
                retval = startup(info);
                if (retval < 0)
                        goto cleanup;
        }

        retval = block_til_ready(tty, filp, info);
        if (retval) {
                if (debug_level >= DEBUG_LEVEL_INFO)
                        printk("%s(%d):block_til_ready(%s) returned %d\n",
                                 __FILE__,__LINE__, info->device_name, retval);
                goto cleanup;
        }

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s(%d):mgsl_open(%s) success\n",
                         __FILE__,__LINE__, info->device_name);
        retval = 0;
        
cleanup:                        
        if (retval) {
                if (tty->count == 1)
                        info->port.tty = NULL; /* tty layer will release tty struct */
                if(info->port.count)
                        info->port.count--;
        }
        
        return retval;
        
}       /* end of mgsl_open() */

/*
 * /proc fs routines....
 */

static inline void line_info(struct seq_file *m, struct mgsl_struct *info)
{
        char    stat_buf[30];
        unsigned long flags;

        if (info->bus_type == MGSL_BUS_TYPE_PCI) {
                seq_printf(m, "%s:PCI io:%04X irq:%d mem:%08X lcr:%08X",
                        info->device_name, info->io_base, info->irq_level,
                        info->phys_memory_base, info->phys_lcr_base);
        } else {
                seq_printf(m, "%s:(E)ISA io:%04X irq:%d dma:%d",
                        info->device_name, info->io_base, 
                        info->irq_level, info->dma_level);
        }

        /* output current serial signal states */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_get_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        stat_buf[0] = 0;
        stat_buf[1] = 0;
        if (info->serial_signals & SerialSignal_RTS)
                strcat(stat_buf, "|RTS");
        if (info->serial_signals & SerialSignal_CTS)
                strcat(stat_buf, "|CTS");
        if (info->serial_signals & SerialSignal_DTR)
                strcat(stat_buf, "|DTR");
        if (info->serial_signals & SerialSignal_DSR)
                strcat(stat_buf, "|DSR");
        if (info->serial_signals & SerialSignal_DCD)
                strcat(stat_buf, "|CD");
        if (info->serial_signals & SerialSignal_RI)
                strcat(stat_buf, "|RI");

        if (info->params.mode == MGSL_MODE_HDLC ||
            info->params.mode == MGSL_MODE_RAW ) {
                seq_printf(m, " HDLC txok:%d rxok:%d",
                              info->icount.txok, info->icount.rxok);
                if (info->icount.txunder)
                        seq_printf(m, " txunder:%d", info->icount.txunder);
                if (info->icount.txabort)
                        seq_printf(m, " txabort:%d", info->icount.txabort);
                if (info->icount.rxshort)
                        seq_printf(m, " rxshort:%d", info->icount.rxshort);
                if (info->icount.rxlong)
                        seq_printf(m, " rxlong:%d", info->icount.rxlong);
                if (info->icount.rxover)
                        seq_printf(m, " rxover:%d", info->icount.rxover);
                if (info->icount.rxcrc)
                        seq_printf(m, " rxcrc:%d", info->icount.rxcrc);
        } else {
                seq_printf(m, " ASYNC tx:%d rx:%d",
                              info->icount.tx, info->icount.rx);
                if (info->icount.frame)
                        seq_printf(m, " fe:%d", info->icount.frame);
                if (info->icount.parity)
                        seq_printf(m, " pe:%d", info->icount.parity);
                if (info->icount.brk)
                        seq_printf(m, " brk:%d", info->icount.brk);
                if (info->icount.overrun)
                        seq_printf(m, " oe:%d", info->icount.overrun);
        }
        
        /* Append serial signal status to end */
        seq_printf(m, " %s\n", stat_buf+1);
        
        seq_printf(m, "txactive=%d bh_req=%d bh_run=%d pending_bh=%x\n",
         info->tx_active,info->bh_requested,info->bh_running,
         info->pending_bh);
         
        spin_lock_irqsave(&info->irq_spinlock,flags);
        {       
        u16 Tcsr = usc_InReg( info, TCSR );
        u16 Tdmr = usc_InDmaReg( info, TDMR );
        u16 Ticr = usc_InReg( info, TICR );
        u16 Rscr = usc_InReg( info, RCSR );
        u16 Rdmr = usc_InDmaReg( info, RDMR );
        u16 Ricr = usc_InReg( info, RICR );
        u16 Icr = usc_InReg( info, ICR );
        u16 Dccr = usc_InReg( info, DCCR );
        u16 Tmr = usc_InReg( info, TMR );
        u16 Tccr = usc_InReg( info, TCCR );
        u16 Ccar = inw( info->io_base + CCAR );
        seq_printf(m, "tcsr=%04X tdmr=%04X ticr=%04X rcsr=%04X rdmr=%04X\n"
                        "ricr=%04X icr =%04X dccr=%04X tmr=%04X tccr=%04X ccar=%04X\n",
                        Tcsr,Tdmr,Ticr,Rscr,Rdmr,Ricr,Icr,Dccr,Tmr,Tccr,Ccar );
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
}

/* Called to print information about devices */
static int mgsl_proc_show(struct seq_file *m, void *v)
{
        struct mgsl_struct *info;
        
        seq_printf(m, "synclink driver:%s\n", driver_version);
        
        info = mgsl_device_list;
        while( info ) {
                line_info(m, info);
                info = info->next_device;
        }
        return 0;
}

static int mgsl_proc_open(struct inode *inode, struct file *file)
{
        return single_open(file, mgsl_proc_show, NULL);
}

static const struct file_operations mgsl_proc_fops = {
        .owner          = THIS_MODULE,
        .open           = mgsl_proc_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

/* mgsl_allocate_dma_buffers()
 * 
 *      Allocate and format DMA buffers (ISA adapter)
 *      or format shared memory buffers (PCI adapter).
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        0 if success, otherwise error
 */
static int mgsl_allocate_dma_buffers(struct mgsl_struct *info)
{
        unsigned short BuffersPerFrame;

        info->last_mem_alloc = 0;

        /* Calculate the number of DMA buffers necessary to hold the */
        /* largest allowable frame size. Note: If the max frame size is */
        /* not an even multiple of the DMA buffer size then we need to */
        /* round the buffer count per frame up one. */

        BuffersPerFrame = (unsigned short)(info->max_frame_size/DMABUFFERSIZE);
        if ( info->max_frame_size % DMABUFFERSIZE )
                BuffersPerFrame++;

        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                /*
                 * The PCI adapter has 256KBytes of shared memory to use.
                 * This is 64 PAGE_SIZE buffers.
                 *
                 * The first page is used for padding at this time so the
                 * buffer list does not begin at offset 0 of the PCI
                 * adapter's shared memory.
                 *
                 * The 2nd page is used for the buffer list. A 4K buffer
                 * list can hold 128 DMA_BUFFER structures at 32 bytes
                 * each.
                 *
                 * This leaves 62 4K pages.
                 *
                 * The next N pages are used for transmit frame(s). We
                 * reserve enough 4K page blocks to hold the required
                 * number of transmit dma buffers (num_tx_dma_buffers),
                 * each of MaxFrameSize size.
                 *
                 * Of the remaining pages (62-N), determine how many can
                 * be used to receive full MaxFrameSize inbound frames
                 */
                info->tx_buffer_count = info->num_tx_dma_buffers * BuffersPerFrame;
                info->rx_buffer_count = 62 - info->tx_buffer_count;
        } else {
                /* Calculate the number of PAGE_SIZE buffers needed for */
                /* receive and transmit DMA buffers. */


                /* Calculate the number of DMA buffers necessary to */
                /* hold 7 max size receive frames and one max size transmit frame. */
                /* The receive buffer count is bumped by one so we avoid an */
                /* End of List condition if all receive buffers are used when */
                /* using linked list DMA buffers. */

                info->tx_buffer_count = info->num_tx_dma_buffers * BuffersPerFrame;
                info->rx_buffer_count = (BuffersPerFrame * MAXRXFRAMES) + 6;
                
                /* 
                 * limit total TxBuffers & RxBuffers to 62 4K total 
                 * (ala PCI Allocation) 
                 */
                
                if ( (info->tx_buffer_count + info->rx_buffer_count) > 62 )
                        info->rx_buffer_count = 62 - info->tx_buffer_count;

        }

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s(%d):Allocating %d TX and %d RX DMA buffers.\n",
                        __FILE__,__LINE__, info->tx_buffer_count,info->rx_buffer_count);
        
        if ( mgsl_alloc_buffer_list_memory( info ) < 0 ||
                  mgsl_alloc_frame_memory(info, info->rx_buffer_list, info->rx_buffer_count) < 0 || 
                  mgsl_alloc_frame_memory(info, info->tx_buffer_list, info->tx_buffer_count) < 0 || 
                  mgsl_alloc_intermediate_rxbuffer_memory(info) < 0  ||
                  mgsl_alloc_intermediate_txbuffer_memory(info) < 0 ) {
                printk("%s(%d):Can't allocate DMA buffer memory\n",__FILE__,__LINE__);
                return -ENOMEM;
        }
        
        mgsl_reset_rx_dma_buffers( info );
        mgsl_reset_tx_dma_buffers( info );

        return 0;

}       /* end of mgsl_allocate_dma_buffers() */

/*
 * mgsl_alloc_buffer_list_memory()
 * 
 * Allocate a common DMA buffer for use as the
 * receive and transmit buffer lists.
 * 
 * A buffer list is a set of buffer entries where each entry contains
 * a pointer to an actual buffer and a pointer to the next buffer entry
 * (plus some other info about the buffer).
 * 
 * The buffer entries for a list are built to form a circular list so
 * that when the entire list has been traversed you start back at the
 * beginning.
 * 
 * This function allocates memory for just the buffer entries.
 * The links (pointer to next entry) are filled in with the physical
 * address of the next entry so the adapter can navigate the list
 * using bus master DMA. The pointers to the actual buffers are filled
 * out later when the actual buffers are allocated.
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        0 if success, otherwise error
 */
static int mgsl_alloc_buffer_list_memory( struct mgsl_struct *info )
{
        unsigned int i;

        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                /* PCI adapter uses shared memory. */
                info->buffer_list = info->memory_base + info->last_mem_alloc;
                info->buffer_list_phys = info->last_mem_alloc;
                info->last_mem_alloc += BUFFERLISTSIZE;
        } else {
                /* ISA adapter uses system memory. */
                /* The buffer lists are allocated as a common buffer that both */
                /* the processor and adapter can access. This allows the driver to */
                /* inspect portions of the buffer while other portions are being */
                /* updated by the adapter using Bus Master DMA. */

                info->buffer_list = dma_alloc_coherent(NULL, BUFFERLISTSIZE, &info->buffer_list_dma_addr, GFP_KERNEL);
                if (info->buffer_list == NULL)
                        return -ENOMEM;
                info->buffer_list_phys = (u32)(info->buffer_list_dma_addr);
        }

        /* We got the memory for the buffer entry lists. */
        /* Initialize the memory block to all zeros. */
        memset( info->buffer_list, 0, BUFFERLISTSIZE );

        /* Save virtual address pointers to the receive and */
        /* transmit buffer lists. (Receive 1st). These pointers will */
        /* be used by the processor to access the lists. */
        info->rx_buffer_list = (DMABUFFERENTRY *)info->buffer_list;
        info->tx_buffer_list = (DMABUFFERENTRY *)info->buffer_list;
        info->tx_buffer_list += info->rx_buffer_count;

        /*
         * Build the links for the buffer entry lists such that
         * two circular lists are built. (Transmit and Receive).
         *
         * Note: the links are physical addresses
         * which are read by the adapter to determine the next
         * buffer entry to use.
         */

        for ( i = 0; i < info->rx_buffer_count; i++ ) {
                /* calculate and store physical address of this buffer entry */
                info->rx_buffer_list[i].phys_entry =
                        info->buffer_list_phys + (i * sizeof(DMABUFFERENTRY));

                /* calculate and store physical address of */
                /* next entry in cirular list of entries */

                info->rx_buffer_list[i].link = info->buffer_list_phys;

                if ( i < info->rx_buffer_count - 1 )
                        info->rx_buffer_list[i].link += (i + 1) * sizeof(DMABUFFERENTRY);
        }

        for ( i = 0; i < info->tx_buffer_count; i++ ) {
                /* calculate and store physical address of this buffer entry */
                info->tx_buffer_list[i].phys_entry = info->buffer_list_phys +
                        ((info->rx_buffer_count + i) * sizeof(DMABUFFERENTRY));

                /* calculate and store physical address of */
                /* next entry in cirular list of entries */

                info->tx_buffer_list[i].link = info->buffer_list_phys +
                        info->rx_buffer_count * sizeof(DMABUFFERENTRY);

                if ( i < info->tx_buffer_count - 1 )
                        info->tx_buffer_list[i].link += (i + 1) * sizeof(DMABUFFERENTRY);
        }

        return 0;

}       /* end of mgsl_alloc_buffer_list_memory() */

/* Free DMA buffers allocated for use as the
 * receive and transmit buffer lists.
 * Warning:
 * 
 *      The data transfer buffers associated with the buffer list
 *      MUST be freed before freeing the buffer list itself because
 *      the buffer list contains the information necessary to free
 *      the individual buffers!
 */
static void mgsl_free_buffer_list_memory( struct mgsl_struct *info )
{
        if (info->buffer_list && info->bus_type != MGSL_BUS_TYPE_PCI)
                dma_free_coherent(NULL, BUFFERLISTSIZE, info->buffer_list, info->buffer_list_dma_addr);
                
        info->buffer_list = NULL;
        info->rx_buffer_list = NULL;
        info->tx_buffer_list = NULL;

}       /* end of mgsl_free_buffer_list_memory() */

/*
 * mgsl_alloc_frame_memory()
 * 
 *      Allocate the frame DMA buffers used by the specified buffer list.
 *      Each DMA buffer will be one memory page in size. This is necessary
 *      because memory can fragment enough that it may be impossible
 *      contiguous pages.
 * 
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      BufferList      pointer to list of buffer entries
 *      Buffercount     count of buffer entries in buffer list
 * 
 * Return Value:        0 if success, otherwise -ENOMEM
 */
static int mgsl_alloc_frame_memory(struct mgsl_struct *info,DMABUFFERENTRY *BufferList,int Buffercount)
{
        int i;
        u32 phys_addr;

        /* Allocate page sized buffers for the receive buffer list */

        for ( i = 0; i < Buffercount; i++ ) {
                if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                        /* PCI adapter uses shared memory buffers. */
                        BufferList[i].virt_addr = info->memory_base + info->last_mem_alloc;
                        phys_addr = info->last_mem_alloc;
                        info->last_mem_alloc += DMABUFFERSIZE;
                } else {
                        /* ISA adapter uses system memory. */
                        BufferList[i].virt_addr = dma_alloc_coherent(NULL, DMABUFFERSIZE, &BufferList[i].dma_addr, GFP_KERNEL);
                        if (BufferList[i].virt_addr == NULL)
                                return -ENOMEM;
                        phys_addr = (u32)(BufferList[i].dma_addr);
                }
                BufferList[i].phys_addr = phys_addr;
        }

        return 0;

}       /* end of mgsl_alloc_frame_memory() */

/*
 * mgsl_free_frame_memory()
 * 
 *      Free the buffers associated with
 *      each buffer entry of a buffer list.
 * 
 * Arguments:
 * 
 *      info            pointer to device instance data
 *      BufferList      pointer to list of buffer entries
 *      Buffercount     count of buffer entries in buffer list
 * 
 * Return Value:        None
 */
static void mgsl_free_frame_memory(struct mgsl_struct *info, DMABUFFERENTRY *BufferList, int Buffercount)
{
        int i;

        if ( BufferList ) {
                for ( i = 0 ; i < Buffercount ; i++ ) {
                        if ( BufferList[i].virt_addr ) {
                                if ( info->bus_type != MGSL_BUS_TYPE_PCI )
                                        dma_free_coherent(NULL, DMABUFFERSIZE, BufferList[i].virt_addr, BufferList[i].dma_addr);
                                BufferList[i].virt_addr = NULL;
                        }
                }
        }

}       /* end of mgsl_free_frame_memory() */

/* mgsl_free_dma_buffers()
 * 
 *      Free DMA buffers
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_free_dma_buffers( struct mgsl_struct *info )
{
        mgsl_free_frame_memory( info, info->rx_buffer_list, info->rx_buffer_count );
        mgsl_free_frame_memory( info, info->tx_buffer_list, info->tx_buffer_count );
        mgsl_free_buffer_list_memory( info );

}       /* end of mgsl_free_dma_buffers() */


/*
 * mgsl_alloc_intermediate_rxbuffer_memory()
 * 
 *      Allocate a buffer large enough to hold max_frame_size. This buffer
 *      is used to pass an assembled frame to the line discipline.
 * 
 * Arguments:
 * 
 *      info            pointer to device instance data
 * 
 * Return Value:        0 if success, otherwise -ENOMEM
 */
static int mgsl_alloc_intermediate_rxbuffer_memory(struct mgsl_struct *info)
{
        info->intermediate_rxbuffer = kmalloc(info->max_frame_size, GFP_KERNEL | GFP_DMA);
        if ( info->intermediate_rxbuffer == NULL )
                return -ENOMEM;
        /* unused flag buffer to satisfy receive_buf calling interface */
        info->flag_buf = kzalloc(info->max_frame_size, GFP_KERNEL);
        if (!info->flag_buf) {
                kfree(info->intermediate_rxbuffer);
                info->intermediate_rxbuffer = NULL;
                return -ENOMEM;
        }
        return 0;

}       /* end of mgsl_alloc_intermediate_rxbuffer_memory() */

/*
 * mgsl_free_intermediate_rxbuffer_memory()
 * 
 * 
 * Arguments:
 * 
 *      info            pointer to device instance data
 * 
 * Return Value:        None
 */
static void mgsl_free_intermediate_rxbuffer_memory(struct mgsl_struct *info)
{
        kfree(info->intermediate_rxbuffer);
        info->intermediate_rxbuffer = NULL;
        kfree(info->flag_buf);
        info->flag_buf = NULL;

}       /* end of mgsl_free_intermediate_rxbuffer_memory() */

/*
 * mgsl_alloc_intermediate_txbuffer_memory()
 *
 *      Allocate intermdiate transmit buffer(s) large enough to hold max_frame_size.
 *      This buffer is used to load transmit frames into the adapter's dma transfer
 *      buffers when there is sufficient space.
 *
 * Arguments:
 *
 *      info            pointer to device instance data
 *
 * Return Value:        0 if success, otherwise -ENOMEM
 */
static int mgsl_alloc_intermediate_txbuffer_memory(struct mgsl_struct *info)
{
        int i;

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk("%s %s(%d)  allocating %d tx holding buffers\n",
                                info->device_name, __FILE__,__LINE__,info->num_tx_holding_buffers);

        memset(info->tx_holding_buffers,0,sizeof(info->tx_holding_buffers));

        for ( i=0; i<info->num_tx_holding_buffers; ++i) {
                info->tx_holding_buffers[i].buffer =
                        kmalloc(info->max_frame_size, GFP_KERNEL);
                if (info->tx_holding_buffers[i].buffer == NULL) {
                        for (--i; i >= 0; i--) {
                                kfree(info->tx_holding_buffers[i].buffer);
                                info->tx_holding_buffers[i].buffer = NULL;
                        }
                        return -ENOMEM;
                }
        }

        return 0;

}       /* end of mgsl_alloc_intermediate_txbuffer_memory() */

/*
 * mgsl_free_intermediate_txbuffer_memory()
 *
 *
 * Arguments:
 *
 *      info            pointer to device instance data
 *
 * Return Value:        None
 */
static void mgsl_free_intermediate_txbuffer_memory(struct mgsl_struct *info)
{
        int i;

        for ( i=0; i<info->num_tx_holding_buffers; ++i ) {
                kfree(info->tx_holding_buffers[i].buffer);
                info->tx_holding_buffers[i].buffer = NULL;
        }

        info->get_tx_holding_index = 0;
        info->put_tx_holding_index = 0;
        info->tx_holding_count = 0;

}       /* end of mgsl_free_intermediate_txbuffer_memory() */


/*
 * load_next_tx_holding_buffer()
 *
 * attempts to load the next buffered tx request into the
 * tx dma buffers
 *
 * Arguments:
 *
 *      info            pointer to device instance data
 *
 * Return Value:        true if next buffered tx request loaded
 *                      into adapter's tx dma buffer,
 *                      false otherwise
 */
static bool load_next_tx_holding_buffer(struct mgsl_struct *info)
{
        bool ret = false;

        if ( info->tx_holding_count ) {
                /* determine if we have enough tx dma buffers
                 * to accommodate the next tx frame
                 */
                struct tx_holding_buffer *ptx =
                        &info->tx_holding_buffers[info->get_tx_holding_index];
                int num_free = num_free_tx_dma_buffers(info);
                int num_needed = ptx->buffer_size / DMABUFFERSIZE;
                if ( ptx->buffer_size % DMABUFFERSIZE )
                        ++num_needed;

                if (num_needed <= num_free) {
                        info->xmit_cnt = ptx->buffer_size;
                        mgsl_load_tx_dma_buffer(info,ptx->buffer,ptx->buffer_size);

                        --info->tx_holding_count;
                        if ( ++info->get_tx_holding_index >= info->num_tx_holding_buffers)
                                info->get_tx_holding_index=0;

                        /* restart transmit timer */
                        mod_timer(&info->tx_timer, jiffies + msecs_to_jiffies(5000));

                        ret = true;
                }
        }

        return ret;
}

/*
 * save_tx_buffer_request()
 *
 * attempt to store transmit frame request for later transmission
 *
 * Arguments:
 *
 *      info            pointer to device instance data
 *      Buffer          pointer to buffer containing frame to load
 *      BufferSize      size in bytes of frame in Buffer
 *
 * Return Value:        1 if able to store, 0 otherwise
 */
static int save_tx_buffer_request(struct mgsl_struct *info,const char *Buffer, unsigned int BufferSize)
{
        struct tx_holding_buffer *ptx;

        if ( info->tx_holding_count >= info->num_tx_holding_buffers ) {
                return 0;               /* all buffers in use */
        }

        ptx = &info->tx_holding_buffers[info->put_tx_holding_index];
        ptx->buffer_size = BufferSize;
        memcpy( ptx->buffer, Buffer, BufferSize);

        ++info->tx_holding_count;
        if ( ++info->put_tx_holding_index >= info->num_tx_holding_buffers)
                info->put_tx_holding_index=0;

        return 1;
}

static int mgsl_claim_resources(struct mgsl_struct *info)
{
        if (request_region(info->io_base,info->io_addr_size,"synclink") == NULL) {
                printk( "%s(%d):I/O address conflict on device %s Addr=%08X\n",
                        __FILE__,__LINE__,info->device_name, info->io_base);
                return -ENODEV;
        }
        info->io_addr_requested = true;
        
        if ( request_irq(info->irq_level,mgsl_interrupt,info->irq_flags,
                info->device_name, info ) < 0 ) {
                printk( "%s(%d):Can't request interrupt on device %s IRQ=%d\n",
                        __FILE__,__LINE__,info->device_name, info->irq_level );
                goto errout;
        }
        info->irq_requested = true;
        
        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                if (request_mem_region(info->phys_memory_base,0x40000,"synclink") == NULL) {
                        printk( "%s(%d):mem addr conflict device %s Addr=%08X\n",
                                __FILE__,__LINE__,info->device_name, info->phys_memory_base);
                        goto errout;
                }
                info->shared_mem_requested = true;
                if (request_mem_region(info->phys_lcr_base + info->lcr_offset,128,"synclink") == NULL) {
                        printk( "%s(%d):lcr mem addr conflict device %s Addr=%08X\n",
                                __FILE__,__LINE__,info->device_name, info->phys_lcr_base + info->lcr_offset);
                        goto errout;
                }
                info->lcr_mem_requested = true;

                info->memory_base = ioremap_nocache(info->phys_memory_base,
                                                                0x40000);
                if (!info->memory_base) {
                        printk( "%s(%d):Can't map shared memory on device %s MemAddr=%08X\n",
                                __FILE__,__LINE__,info->device_name, info->phys_memory_base );
                        goto errout;
                }
                
                if ( !mgsl_memory_test(info) ) {
                        printk( "%s(%d):Failed shared memory test %s MemAddr=%08X\n",
                                __FILE__,__LINE__,info->device_name, info->phys_memory_base );
                        goto errout;
                }
                
                info->lcr_base = ioremap_nocache(info->phys_lcr_base,
                                                                PAGE_SIZE);
                if (!info->lcr_base) {
                        printk( "%s(%d):Can't map LCR memory on device %s MemAddr=%08X\n",
                                __FILE__,__LINE__,info->device_name, info->phys_lcr_base );
                        goto errout;
                }
                info->lcr_base += info->lcr_offset;
                
        } else {
                /* claim DMA channel */
                
                if (request_dma(info->dma_level,info->device_name) < 0){
                        printk( "%s(%d):Can't request DMA channel on device %s DMA=%d\n",
                                __FILE__,__LINE__,info->device_name, info->dma_level );
                        goto errout;
                }
                info->dma_requested = true;

                /* ISA adapter uses bus master DMA */           
                set_dma_mode(info->dma_level,DMA_MODE_CASCADE);
                enable_dma(info->dma_level);
        }
        
        if ( mgsl_allocate_dma_buffers(info) < 0 ) {
                printk( "%s(%d):Can't allocate DMA buffers on device %s DMA=%d\n",
                        __FILE__,__LINE__,info->device_name, info->dma_level );
                goto errout;
        }       
        
        return 0;
errout:
        mgsl_release_resources(info);
        return -ENODEV;

}       /* end of mgsl_claim_resources() */

static void mgsl_release_resources(struct mgsl_struct *info)
{
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_release_resources(%s) entry\n",
                        __FILE__,__LINE__,info->device_name );
                        
        if ( info->irq_requested ) {
                free_irq(info->irq_level, info);
                info->irq_requested = false;
        }
        if ( info->dma_requested ) {
                disable_dma(info->dma_level);
                free_dma(info->dma_level);
                info->dma_requested = false;
        }
        mgsl_free_dma_buffers(info);
        mgsl_free_intermediate_rxbuffer_memory(info);
        mgsl_free_intermediate_txbuffer_memory(info);
        
        if ( info->io_addr_requested ) {
                release_region(info->io_base,info->io_addr_size);
                info->io_addr_requested = false;
        }
        if ( info->shared_mem_requested ) {
                release_mem_region(info->phys_memory_base,0x40000);
                info->shared_mem_requested = false;
        }
        if ( info->lcr_mem_requested ) {
                release_mem_region(info->phys_lcr_base + info->lcr_offset,128);
                info->lcr_mem_requested = false;
        }
        if (info->memory_base){
                iounmap(info->memory_base);
                info->memory_base = NULL;
        }
        if (info->lcr_base){
                iounmap(info->lcr_base - info->lcr_offset);
                info->lcr_base = NULL;
        }
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_release_resources(%s) exit\n",
                        __FILE__,__LINE__,info->device_name );
                        
}       /* end of mgsl_release_resources() */

/* mgsl_add_device()
 * 
 *      Add the specified device instance data structure to the
 *      global linked list of devices and increment the device count.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_add_device( struct mgsl_struct *info )
{
        info->next_device = NULL;
        info->line = mgsl_device_count;
        sprintf(info->device_name,"ttySL%d",info->line);
        
        if (info->line < MAX_TOTAL_DEVICES) {
                if (maxframe[info->line])
                        info->max_frame_size = maxframe[info->line];

                if (txdmabufs[info->line]) {
                        info->num_tx_dma_buffers = txdmabufs[info->line];
                        if (info->num_tx_dma_buffers < 1)
                                info->num_tx_dma_buffers = 1;
                }

                if (txholdbufs[info->line]) {
                        info->num_tx_holding_buffers = txholdbufs[info->line];
                        if (info->num_tx_holding_buffers < 1)
                                info->num_tx_holding_buffers = 1;
                        else if (info->num_tx_holding_buffers > MAX_TX_HOLDING_BUFFERS)
                                info->num_tx_holding_buffers = MAX_TX_HOLDING_BUFFERS;
                }
        }

        mgsl_device_count++;
        
        if ( !mgsl_device_list )
                mgsl_device_list = info;
        else {  
                struct mgsl_struct *current_dev = mgsl_device_list;
                while( current_dev->next_device )
                        current_dev = current_dev->next_device;
                current_dev->next_device = info;
        }
        
        if ( info->max_frame_size < 4096 )
                info->max_frame_size = 4096;
        else if ( info->max_frame_size > 65535 )
                info->max_frame_size = 65535;
        
        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                printk( "SyncLink PCI v%d %s: IO=%04X IRQ=%d Mem=%08X,%08X MaxFrameSize=%u\n",
                        info->hw_version + 1, info->device_name, info->io_base, info->irq_level,
                        info->phys_memory_base, info->phys_lcr_base,
                        info->max_frame_size );
        } else {
                printk( "SyncLink ISA %s: IO=%04X IRQ=%d DMA=%d MaxFrameSize=%u\n",
                        info->device_name, info->io_base, info->irq_level, info->dma_level,
                        info->max_frame_size );
        }

#if SYNCLINK_GENERIC_HDLC
        hdlcdev_init(info);
#endif

}       /* end of mgsl_add_device() */

static const struct tty_port_operations mgsl_port_ops = {
        .carrier_raised = carrier_raised,
        .dtr_rts = dtr_rts,
};


/* mgsl_allocate_device()
 * 
 *      Allocate and initialize a device instance structure
 *      
 * Arguments:           none
 * Return Value:        pointer to mgsl_struct if success, otherwise NULL
 */
static struct mgsl_struct* mgsl_allocate_device(void)
{
        struct mgsl_struct *info;
        
        info = kzalloc(sizeof(struct mgsl_struct),
                 GFP_KERNEL);
                 
        if (!info) {
                printk("Error can't allocate device instance data\n");
        } else {
                tty_port_init(&info->port);
                info->port.ops = &mgsl_port_ops;
                info->magic = MGSL_MAGIC;
                INIT_WORK(&info->task, mgsl_bh_handler);
                info->max_frame_size = 4096;
                info->port.close_delay = 5*HZ/10;
                info->port.closing_wait = 30*HZ;
                init_waitqueue_head(&info->status_event_wait_q);
                init_waitqueue_head(&info->event_wait_q);
                spin_lock_init(&info->irq_spinlock);
                spin_lock_init(&info->netlock);
                memcpy(&info->params,&default_params,sizeof(MGSL_PARAMS));
                info->idle_mode = HDLC_TXIDLE_FLAGS;
                info->num_tx_dma_buffers = 1;
                info->num_tx_holding_buffers = 0;
        }
        
        return info;

}       /* end of mgsl_allocate_device()*/

static const struct tty_operations mgsl_ops = {
        .install = mgsl_install,
        .open = mgsl_open,
        .close = mgsl_close,
        .write = mgsl_write,
        .put_char = mgsl_put_char,
        .flush_chars = mgsl_flush_chars,
        .write_room = mgsl_write_room,
        .chars_in_buffer = mgsl_chars_in_buffer,
        .flush_buffer = mgsl_flush_buffer,
        .ioctl = mgsl_ioctl,
        .throttle = mgsl_throttle,
        .unthrottle = mgsl_unthrottle,
        .send_xchar = mgsl_send_xchar,
        .break_ctl = mgsl_break,
        .wait_until_sent = mgsl_wait_until_sent,
        .set_termios = mgsl_set_termios,
        .stop = mgsl_stop,
        .start = mgsl_start,
        .hangup = mgsl_hangup,
        .tiocmget = tiocmget,
        .tiocmset = tiocmset,
        .get_icount = msgl_get_icount,
        .proc_fops = &mgsl_proc_fops,
};

/*
 * perform tty device initialization
 */
static int mgsl_init_tty(void)
{
        int rc;

        serial_driver = alloc_tty_driver(128);
        if (!serial_driver)
                return -ENOMEM;
        
        serial_driver->driver_name = "synclink";
        serial_driver->name = "ttySL";
        serial_driver->major = ttymajor;
        serial_driver->minor_start = 64;
        serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
        serial_driver->subtype = SERIAL_TYPE_NORMAL;
        serial_driver->init_termios = tty_std_termios;
        serial_driver->init_termios.c_cflag =
                B9600 | CS8 | CREAD | HUPCL | CLOCAL;
        serial_driver->init_termios.c_ispeed = 9600;
        serial_driver->init_termios.c_ospeed = 9600;
        serial_driver->flags = TTY_DRIVER_REAL_RAW;
        tty_set_operations(serial_driver, &mgsl_ops);
        if ((rc = tty_register_driver(serial_driver)) < 0) {
                printk("%s(%d):Couldn't register serial driver\n",
                        __FILE__,__LINE__);
                put_tty_driver(serial_driver);
                serial_driver = NULL;
                return rc;
        }
                        
        printk("%s %s, tty major#%d\n",
                driver_name, driver_version,
                serial_driver->major);
        return 0;
}

/* enumerate user specified ISA adapters
 */
static void mgsl_enum_isa_devices(void)
{
        struct mgsl_struct *info;
        int i;
                
        /* Check for user specified ISA devices */
        
        for (i=0 ;(i < MAX_ISA_DEVICES) && io[i] && irq[i]; i++){
                if ( debug_level >= DEBUG_LEVEL_INFO )
                        printk("ISA device specified io=%04X,irq=%d,dma=%d\n",
                                io[i], irq[i], dma[i] );
                
                info = mgsl_allocate_device();
                if ( !info ) {
                        /* error allocating device instance data */
                        if ( debug_level >= DEBUG_LEVEL_ERROR )
                                printk( "can't allocate device instance data.\n");
                        continue;
                }
                
                /* Copy user configuration info to device instance data */
                info->io_base = (unsigned int)io[i];
                info->irq_level = (unsigned int)irq[i];
                info->irq_level = irq_canonicalize(info->irq_level);
                info->dma_level = (unsigned int)dma[i];
                info->bus_type = MGSL_BUS_TYPE_ISA;
                info->io_addr_size = 16;
                info->irq_flags = 0;
                
                mgsl_add_device( info );
        }
}

static void synclink_cleanup(void)
{
        int rc;
        struct mgsl_struct *info;
        struct mgsl_struct *tmp;

        printk("Unloading %s: %s\n", driver_name, driver_version);

        if (serial_driver) {
                rc = tty_unregister_driver(serial_driver);
                if (rc)
                        printk("%s(%d) failed to unregister tty driver err=%d\n",
                               __FILE__,__LINE__,rc);
                put_tty_driver(serial_driver);
        }

        info = mgsl_device_list;
        while(info) {
#if SYNCLINK_GENERIC_HDLC
                hdlcdev_exit(info);
#endif
                mgsl_release_resources(info);
                tmp = info;
                info = info->next_device;
                tty_port_destroy(&tmp->port);
                kfree(tmp);
        }
        
        if (pci_registered)
                pci_unregister_driver(&synclink_pci_driver);
}

static int __init synclink_init(void)
{
        int rc;

        if (break_on_load) {
                mgsl_get_text_ptr();
                BREAKPOINT();
        }

        printk("%s %s\n", driver_name, driver_version);

        mgsl_enum_isa_devices();
        if ((rc = pci_register_driver(&synclink_pci_driver)) < 0)
                printk("%s:failed to register PCI driver, error=%d\n",__FILE__,rc);
        else
                pci_registered = true;

        if ((rc = mgsl_init_tty()) < 0)
                goto error;

        return 0;

error:
        synclink_cleanup();
        return rc;
}

static void __exit synclink_exit(void)
{
        synclink_cleanup();
}

module_init(synclink_init);
module_exit(synclink_exit);

/*
 * usc_RTCmd()
 *
 * Issue a USC Receive/Transmit command to the
 * Channel Command/Address Register (CCAR).
 *
 * Notes:
 *
 *    The command is encoded in the most significant 5 bits <15..11>
 *    of the CCAR value. Bits <10..7> of the CCAR must be preserved
 *    and Bits <6..0> must be written as zeros.
 *
 * Arguments:
 *
 *    info   pointer to device information structure
 *    Cmd    command mask (use symbolic macros)
 *
 * Return Value:
 *
 *    None
 */
static void usc_RTCmd( struct mgsl_struct *info, u16 Cmd )
{
        /* output command to CCAR in bits <15..11> */
        /* preserve bits <10..7>, bits <6..0> must be zero */

        outw( Cmd + info->loopback_bits, info->io_base + CCAR );

        /* Read to flush write to CCAR */
        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                inw( info->io_base + CCAR );

}       /* end of usc_RTCmd() */

/*
 * usc_DmaCmd()
 *
 *    Issue a DMA command to the DMA Command/Address Register (DCAR).
 *
 * Arguments:
 *
 *    info   pointer to device information structure
 *    Cmd    DMA command mask (usc_DmaCmd_XX Macros)
 *
 * Return Value:
 *
 *       None
 */
static void usc_DmaCmd( struct mgsl_struct *info, u16 Cmd )
{
        /* write command mask to DCAR */
        outw( Cmd + info->mbre_bit, info->io_base );

        /* Read to flush write to DCAR */
        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                inw( info->io_base );

}       /* end of usc_DmaCmd() */

/*
 * usc_OutDmaReg()
 *
 *    Write a 16-bit value to a USC DMA register
 *
 * Arguments:
 *
 *    info      pointer to device info structure
 *    RegAddr   register address (number) for write
 *    RegValue  16-bit value to write to register
 *
 * Return Value:
 *
 *    None
 *
 */
static void usc_OutDmaReg( struct mgsl_struct *info, u16 RegAddr, u16 RegValue )
{
        /* Note: The DCAR is located at the adapter base address */
        /* Note: must preserve state of BIT8 in DCAR */

        outw( RegAddr + info->mbre_bit, info->io_base );
        outw( RegValue, info->io_base );

        /* Read to flush write to DCAR */
        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                inw( info->io_base );

}       /* end of usc_OutDmaReg() */
 
/*
 * usc_InDmaReg()
 *
 *    Read a 16-bit value from a DMA register
 *
 * Arguments:
 *
 *    info     pointer to device info structure
 *    RegAddr  register address (number) to read from
 *
 * Return Value:
 *
 *    The 16-bit value read from register
 *
 */
static u16 usc_InDmaReg( struct mgsl_struct *info, u16 RegAddr )
{
        /* Note: The DCAR is located at the adapter base address */
        /* Note: must preserve state of BIT8 in DCAR */

        outw( RegAddr + info->mbre_bit, info->io_base );
        return inw( info->io_base );

}       /* end of usc_InDmaReg() */

/*
 *
 * usc_OutReg()
 *
 *    Write a 16-bit value to a USC serial channel register 
 *
 * Arguments:
 *
 *    info      pointer to device info structure
 *    RegAddr   register address (number) to write to
 *    RegValue  16-bit value to write to register
 *
 * Return Value:
 *
 *    None
 *
 */
static void usc_OutReg( struct mgsl_struct *info, u16 RegAddr, u16 RegValue )
{
        outw( RegAddr + info->loopback_bits, info->io_base + CCAR );
        outw( RegValue, info->io_base + CCAR );

        /* Read to flush write to CCAR */
        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                inw( info->io_base + CCAR );

}       /* end of usc_OutReg() */

/*
 * usc_InReg()
 *
 *    Reads a 16-bit value from a USC serial channel register
 *
 * Arguments:
 *
 *    info       pointer to device extension
 *    RegAddr    register address (number) to read from
 *
 * Return Value:
 *
 *    16-bit value read from register
 */
static u16 usc_InReg( struct mgsl_struct *info, u16 RegAddr )
{
        outw( RegAddr + info->loopback_bits, info->io_base + CCAR );
        return inw( info->io_base + CCAR );

}       /* end of usc_InReg() */

/* usc_set_sdlc_mode()
 *
 *    Set up the adapter for SDLC DMA communications.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        NONE
 */
static void usc_set_sdlc_mode( struct mgsl_struct *info )
{
        u16 RegValue;
        bool PreSL1660;
        
        /*
         * determine if the IUSC on the adapter is pre-SL1660. If
         * not, take advantage of the UnderWait feature of more
         * modern chips. If an underrun occurs and this bit is set,
         * the transmitter will idle the programmed idle pattern
         * until the driver has time to service the underrun. Otherwise,
         * the dma controller may get the cycles previously requested
         * and begin transmitting queued tx data.
         */
        usc_OutReg(info,TMCR,0x1f);
        RegValue=usc_InReg(info,TMDR);
        PreSL1660 = (RegValue == IUSC_PRE_SL1660);

        if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
        {
           /*
           ** Channel Mode Register (CMR)
           **
           ** <15..14>    10    Tx Sub Modes, Send Flag on Underrun
           ** <13>        0     0 = Transmit Disabled (initially)
           ** <12>        0     1 = Consecutive Idles share common 0
           ** <11..8>     1110  Transmitter Mode = HDLC/SDLC Loop
           ** <7..4>      0000  Rx Sub Modes, addr/ctrl field handling
           ** <3..0>      0110  Receiver Mode = HDLC/SDLC
           **
           ** 1000 1110 0000 0110 = 0x8e06
           */
           RegValue = 0x8e06;
 
           /*--------------------------------------------------
            * ignore user options for UnderRun Actions and
            * preambles
            *--------------------------------------------------*/
        }
        else
        {       
                /* Channel mode Register (CMR)
                 *
                 * <15..14>  00    Tx Sub modes, Underrun Action
                 * <13>      0     1 = Send Preamble before opening flag
                 * <12>      0     1 = Consecutive Idles share common 0
                 * <11..8>   0110  Transmitter mode = HDLC/SDLC
                 * <7..4>    0000  Rx Sub modes, addr/ctrl field handling
                 * <3..0>    0110  Receiver mode = HDLC/SDLC
                 *
                 * 0000 0110 0000 0110 = 0x0606
                 */
                if (info->params.mode == MGSL_MODE_RAW) {
                        RegValue = 0x0001;              /* Set Receive mode = external sync */

                        usc_OutReg( info, IOCR,         /* Set IOCR DCD is RxSync Detect Input */
                                (unsigned short)((usc_InReg(info, IOCR) & ~(BIT13|BIT12)) | BIT12));

                        /*
                         * TxSubMode:
                         *      CMR <15>                0       Don't send CRC on Tx Underrun
                         *      CMR <14>                x       undefined
                         *      CMR <13>                0       Send preamble before openning sync
                         *      CMR <12>                0       Send 8-bit syncs, 1=send Syncs per TxLength
                         *
                         * TxMode:
                         *      CMR <11-8)      0100    MonoSync
                         *
                         *      0x00 0100 xxxx xxxx  04xx
                         */
                        RegValue |= 0x0400;
                }
                else {

                RegValue = 0x0606;

                if ( info->params.flags & HDLC_FLAG_UNDERRUN_ABORT15 )
                        RegValue |= BIT14;
                else if ( info->params.flags & HDLC_FLAG_UNDERRUN_FLAG )
                        RegValue |= BIT15;
                else if ( info->params.flags & HDLC_FLAG_UNDERRUN_CRC )
                        RegValue |= BIT15 | BIT14;
                }

                if ( info->params.preamble != HDLC_PREAMBLE_PATTERN_NONE )
                        RegValue |= BIT13;
        }

        if ( info->params.mode == MGSL_MODE_HDLC &&
                (info->params.flags & HDLC_FLAG_SHARE_ZERO) )
                RegValue |= BIT12;

        if ( info->params.addr_filter != 0xff )
        {
                /* set up receive address filtering */
                usc_OutReg( info, RSR, info->params.addr_filter );
                RegValue |= BIT4;
        }

        usc_OutReg( info, CMR, RegValue );
        info->cmr_value = RegValue;

        /* Receiver mode Register (RMR)
         *
         * <15..13>  000    encoding
         * <12..11>  00     FCS = 16bit CRC CCITT (x15 + x12 + x5 + 1)
         * <10>      1      1 = Set CRC to all 1s (use for SDLC/HDLC)
         * <9>       0      1 = Include Receive chars in CRC
         * <8>       1      1 = Use Abort/PE bit as abort indicator
         * <7..6>    00     Even parity
         * <5>       0      parity disabled
         * <4..2>    000    Receive Char Length = 8 bits
         * <1..0>    00     Disable Receiver
         *
         * 0000 0101 0000 0000 = 0x0500
         */

        RegValue = 0x0500;

        switch ( info->params.encoding ) {
        case HDLC_ENCODING_NRZB:               RegValue |= BIT13; break;
        case HDLC_ENCODING_NRZI_MARK:          RegValue |= BIT14; break;
        case HDLC_ENCODING_NRZI_SPACE:         RegValue |= BIT14 | BIT13; break;
        case HDLC_ENCODING_BIPHASE_MARK:       RegValue |= BIT15; break;
        case HDLC_ENCODING_BIPHASE_SPACE:      RegValue |= BIT15 | BIT13; break;
        case HDLC_ENCODING_BIPHASE_LEVEL:      RegValue |= BIT15 | BIT14; break;
        case HDLC_ENCODING_DIFF_BIPHASE_LEVEL: RegValue |= BIT15 | BIT14 | BIT13; break;
        }

        if ( (info->params.crc_type & HDLC_CRC_MASK) == HDLC_CRC_16_CCITT )
                RegValue |= BIT9;
        else if ( (info->params.crc_type & HDLC_CRC_MASK) == HDLC_CRC_32_CCITT )
                RegValue |= ( BIT12 | BIT10 | BIT9 );

        usc_OutReg( info, RMR, RegValue );

        /* Set the Receive count Limit Register (RCLR) to 0xffff. */
        /* When an opening flag of an SDLC frame is recognized the */
        /* Receive Character count (RCC) is loaded with the value in */
        /* RCLR. The RCC is decremented for each received byte.  The */
        /* value of RCC is stored after the closing flag of the frame */
        /* allowing the frame size to be computed. */

        usc_OutReg( info, RCLR, RCLRVALUE );

        usc_RCmd( info, RCmd_SelectRicrdma_level );

        /* Receive Interrupt Control Register (RICR)
         *
         * <15..8>      ?       RxFIFO DMA Request Level
         * <7>          0       Exited Hunt IA (Interrupt Arm)
         * <6>          0       Idle Received IA
         * <5>          0       Break/Abort IA
         * <4>          0       Rx Bound IA
         * <3>          1       Queued status reflects oldest 2 bytes in FIFO
         * <2>          0       Abort/PE IA
         * <1>          1       Rx Overrun IA
         * <0>          0       Select TC0 value for readback
         *
         *      0000 0000 0000 1000 = 0x000a
         */

        /* Carry over the Exit Hunt and Idle Received bits */
        /* in case they have been armed by usc_ArmEvents.   */

        RegValue = usc_InReg( info, RICR ) & 0xc0;

        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                usc_OutReg( info, RICR, (u16)(0x030a | RegValue) );
        else
                usc_OutReg( info, RICR, (u16)(0x140a | RegValue) );

        /* Unlatch all Rx status bits and clear Rx status IRQ Pending */

        usc_UnlatchRxstatusBits( info, RXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, RECEIVE_STATUS );

        /* Transmit mode Register (TMR)
         *      
         * <15..13>     000     encoding
         * <12..11>     00      FCS = 16bit CRC CCITT (x15 + x12 + x5 + 1)
         * <10>         1       1 = Start CRC as all 1s (use for SDLC/HDLC)
         * <9>          0       1 = Tx CRC Enabled
         * <8>          0       1 = Append CRC to end of transmit frame
         * <7..6>       00      Transmit parity Even
         * <5>          0       Transmit parity Disabled
         * <4..2>       000     Tx Char Length = 8 bits
         * <1..0>       00      Disable Transmitter
         *
         *      0000 0100 0000 0000 = 0x0400
         */

        RegValue = 0x0400;

        switch ( info->params.encoding ) {
        case HDLC_ENCODING_NRZB:               RegValue |= BIT13; break;
        case HDLC_ENCODING_NRZI_MARK:          RegValue |= BIT14; break;
        case HDLC_ENCODING_NRZI_SPACE:         RegValue |= BIT14 | BIT13; break;
        case HDLC_ENCODING_BIPHASE_MARK:       RegValue |= BIT15; break;
        case HDLC_ENCODING_BIPHASE_SPACE:      RegValue |= BIT15 | BIT13; break;
        case HDLC_ENCODING_BIPHASE_LEVEL:      RegValue |= BIT15 | BIT14; break;
        case HDLC_ENCODING_DIFF_BIPHASE_LEVEL: RegValue |= BIT15 | BIT14 | BIT13; break;
        }

        if ( (info->params.crc_type & HDLC_CRC_MASK) == HDLC_CRC_16_CCITT )
                RegValue |= BIT9 | BIT8;
        else if ( (info->params.crc_type & HDLC_CRC_MASK) == HDLC_CRC_32_CCITT )
                RegValue |= ( BIT12 | BIT10 | BIT9 | BIT8);

        usc_OutReg( info, TMR, RegValue );

        usc_set_txidle( info );


        usc_TCmd( info, TCmd_SelectTicrdma_level );

        /* Transmit Interrupt Control Register (TICR)
         *
         * <15..8>      ?       Transmit FIFO DMA Level
         * <7>          0       Present IA (Interrupt Arm)
         * <6>          0       Idle Sent IA
         * <5>          1       Abort Sent IA
         * <4>          1       EOF/EOM Sent IA
         * <3>          0       CRC Sent IA
         * <2>          1       1 = Wait for SW Trigger to Start Frame
         * <1>          1       Tx Underrun IA
         * <0>          0       TC0 constant on read back
         *
         *      0000 0000 0011 0110 = 0x0036
         */

        if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                usc_OutReg( info, TICR, 0x0736 );
        else                                                            
                usc_OutReg( info, TICR, 0x1436 );

        usc_UnlatchTxstatusBits( info, TXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS );

        /*
        ** Transmit Command/Status Register (TCSR)
        **
        ** <15..12>     0000    TCmd
        ** <11>         0/1     UnderWait
        ** <10..08>     000     TxIdle
        ** <7>          x       PreSent
        ** <6>          x       IdleSent
        ** <5>          x       AbortSent
        ** <4>          x       EOF/EOM Sent
        ** <3>          x       CRC Sent
        ** <2>          x       All Sent
        ** <1>          x       TxUnder
        ** <0>          x       TxEmpty
        ** 
        ** 0000 0000 0000 0000 = 0x0000
        */
        info->tcsr_value = 0;

        if ( !PreSL1660 )
                info->tcsr_value |= TCSR_UNDERWAIT;
                
        usc_OutReg( info, TCSR, info->tcsr_value );

        /* Clock mode Control Register (CMCR)
         *
         * <15..14>     00      counter 1 Source = Disabled
         * <13..12>     00      counter 0 Source = Disabled
         * <11..10>     11      BRG1 Input is TxC Pin
         * <9..8>       11      BRG0 Input is TxC Pin
         * <7..6>       01      DPLL Input is BRG1 Output
         * <5..3>       XXX     TxCLK comes from Port 0
         * <2..0>       XXX     RxCLK comes from Port 1
         *
         *      0000 1111 0111 0111 = 0x0f77
         */

        RegValue = 0x0f40;

        if ( info->params.flags & HDLC_FLAG_RXC_DPLL )
                RegValue |= 0x0003;     /* RxCLK from DPLL */
        else if ( info->params.flags & HDLC_FLAG_RXC_BRG )
                RegValue |= 0x0004;     /* RxCLK from BRG0 */
        else if ( info->params.flags & HDLC_FLAG_RXC_TXCPIN)
                RegValue |= 0x0006;     /* RxCLK from TXC Input */
        else
                RegValue |= 0x0007;     /* RxCLK from Port1 */

        if ( info->params.flags & HDLC_FLAG_TXC_DPLL )
                RegValue |= 0x0018;     /* TxCLK from DPLL */
        else if ( info->params.flags & HDLC_FLAG_TXC_BRG )
                RegValue |= 0x0020;     /* TxCLK from BRG0 */
        else if ( info->params.flags & HDLC_FLAG_TXC_RXCPIN)
                RegValue |= 0x0038;     /* RxCLK from TXC Input */
        else
                RegValue |= 0x0030;     /* TxCLK from Port0 */

        usc_OutReg( info, CMCR, RegValue );


        /* Hardware Configuration Register (HCR)
         *
         * <15..14>     00      CTR0 Divisor:00=32,01=16,10=8,11=4
         * <13>         0       CTR1DSel:0=CTR0Div determines CTR0Div
         * <12>         0       CVOK:0=report code violation in biphase
         * <11..10>     00      DPLL Divisor:00=32,01=16,10=8,11=4
         * <9..8>       XX      DPLL mode:00=disable,01=NRZ,10=Biphase,11=Biphase Level
         * <7..6>       00      reserved
         * <5>          0       BRG1 mode:0=continuous,1=single cycle
         * <4>          X       BRG1 Enable
         * <3..2>       00      reserved
         * <1>          0       BRG0 mode:0=continuous,1=single cycle
         * <0>          0       BRG0 Enable
         */

        RegValue = 0x0000;

        if ( info->params.flags & (HDLC_FLAG_RXC_DPLL | HDLC_FLAG_TXC_DPLL) ) {
                u32 XtalSpeed;
                u32 DpllDivisor;
                u16 Tc;

                /*  DPLL is enabled. Use BRG1 to provide continuous reference clock  */
                /*  for DPLL. DPLL mode in HCR is dependent on the encoding used. */

                if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                        XtalSpeed = 11059200;
                else
                        XtalSpeed = 14745600;

                if ( info->params.flags & HDLC_FLAG_DPLL_DIV16 ) {
                        DpllDivisor = 16;
                        RegValue |= BIT10;
                }
                else if ( info->params.flags & HDLC_FLAG_DPLL_DIV8 ) {
                        DpllDivisor = 8;
                        RegValue |= BIT11;
                }
                else
                        DpllDivisor = 32;

                /*  Tc = (Xtal/Speed) - 1 */
                /*  If twice the remainder of (Xtal/Speed) is greater than Speed */
                /*  then rounding up gives a more precise time constant. Instead */
                /*  of rounding up and then subtracting 1 we just don't subtract */
                /*  the one in this case. */

                /*--------------------------------------------------
                 * ejz: for DPLL mode, application should use the
                 * same clock speed as the partner system, even 
                 * though clocking is derived from the input RxData.
                 * In case the user uses a 0 for the clock speed,
                 * default to 0xffffffff and don't try to divide by
                 * zero
                 *--------------------------------------------------*/
                if ( info->params.clock_speed )
                {
                        Tc = (u16)((XtalSpeed/DpllDivisor)/info->params.clock_speed);
                        if ( !((((XtalSpeed/DpllDivisor) % info->params.clock_speed) * 2)
                               / info->params.clock_speed) )
                                Tc--;
                }
                else
                        Tc = -1;
                                  

                /* Write 16-bit Time Constant for BRG1 */
                usc_OutReg( info, TC1R, Tc );

                RegValue |= BIT4;               /* enable BRG1 */

                switch ( info->params.encoding ) {
                case HDLC_ENCODING_NRZ:
                case HDLC_ENCODING_NRZB:
                case HDLC_ENCODING_NRZI_MARK:
                case HDLC_ENCODING_NRZI_SPACE: RegValue |= BIT8; break;
                case HDLC_ENCODING_BIPHASE_MARK:
                case HDLC_ENCODING_BIPHASE_SPACE: RegValue |= BIT9; break;
                case HDLC_ENCODING_BIPHASE_LEVEL:
                case HDLC_ENCODING_DIFF_BIPHASE_LEVEL: RegValue |= BIT9 | BIT8; break;
                }
        }

        usc_OutReg( info, HCR, RegValue );


        /* Channel Control/status Register (CCSR)
         *
         * <15>         X       RCC FIFO Overflow status (RO)
         * <14>         X       RCC FIFO Not Empty status (RO)
         * <13>         0       1 = Clear RCC FIFO (WO)
         * <12>         X       DPLL Sync (RW)
         * <11>         X       DPLL 2 Missed Clocks status (RO)
         * <10>         X       DPLL 1 Missed Clock status (RO)
         * <9..8>       00      DPLL Resync on rising and falling edges (RW)
         * <7>          X       SDLC Loop On status (RO)
         * <6>          X       SDLC Loop Send status (RO)
         * <5>          1       Bypass counters for TxClk and RxClk (RW)
         * <4..2>       000     Last Char of SDLC frame has 8 bits (RW)
         * <1..0>       00      reserved
         *
         *      0000 0000 0010 0000 = 0x0020
         */

        usc_OutReg( info, CCSR, 0x1020 );


        if ( info->params.flags & HDLC_FLAG_AUTO_CTS ) {
                usc_OutReg( info, SICR,
                            (u16)(usc_InReg(info,SICR) | SICR_CTS_INACTIVE) );
        }
        

        /* enable Master Interrupt Enable bit (MIE) */
        usc_EnableMasterIrqBit( info );

        usc_ClearIrqPendingBits( info, RECEIVE_STATUS | RECEIVE_DATA |
                                TRANSMIT_STATUS | TRANSMIT_DATA | MISC);

        /* arm RCC underflow interrupt */
        usc_OutReg(info, SICR, (u16)(usc_InReg(info,SICR) | BIT3));
        usc_EnableInterrupts(info, MISC);

        info->mbre_bit = 0;
        outw( 0, info->io_base );                       /* clear Master Bus Enable (DCAR) */
        usc_DmaCmd( info, DmaCmd_ResetAllChannels );    /* disable both DMA channels */
        info->mbre_bit = BIT8;
        outw( BIT8, info->io_base );                    /* set Master Bus Enable (DCAR) */

        if (info->bus_type == MGSL_BUS_TYPE_ISA) {
                /* Enable DMAEN (Port 7, Bit 14) */
                /* This connects the DMA request signal to the ISA bus */
                usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT15) & ~BIT14));
        }

        /* DMA Control Register (DCR)
         *
         * <15..14>     10      Priority mode = Alternating Tx/Rx
         *              01      Rx has priority
         *              00      Tx has priority
         *
         * <13>         1       Enable Priority Preempt per DCR<15..14>
         *                      (WARNING DCR<11..10> must be 00 when this is 1)
         *              0       Choose activate channel per DCR<11..10>
         *
         * <12>         0       Little Endian for Array/List
         * <11..10>     00      Both Channels can use each bus grant
         * <9..6>       0000    reserved
         * <5>          0       7 CLK - Minimum Bus Re-request Interval
         * <4>          0       1 = drive D/C and S/D pins
         * <3>          1       1 = Add one wait state to all DMA cycles.
         * <2>          0       1 = Strobe /UAS on every transfer.
         * <1..0>       11      Addr incrementing only affects LS24 bits
         *
         *      0110 0000 0000 1011 = 0x600b
         */

        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                /* PCI adapter does not need DMA wait state */
                usc_OutDmaReg( info, DCR, 0xa00b );
        }
        else
                usc_OutDmaReg( info, DCR, 0x800b );


        /* Receive DMA mode Register (RDMR)
         *
         * <15..14>     11      DMA mode = Linked List Buffer mode
         * <13>         1       RSBinA/L = store Rx status Block in Arrary/List entry
         * <12>         1       Clear count of List Entry after fetching
         * <11..10>     00      Address mode = Increment
         * <9>          1       Terminate Buffer on RxBound
         * <8>          0       Bus Width = 16bits
         * <7..0>       ?       status Bits (write as 0s)
         *
         * 1111 0010 0000 0000 = 0xf200
         */

        usc_OutDmaReg( info, RDMR, 0xf200 );


        /* Transmit DMA mode Register (TDMR)
         *
         * <15..14>     11      DMA mode = Linked List Buffer mode
         * <13>         1       TCBinA/L = fetch Tx Control Block from List entry
         * <12>         1       Clear count of List Entry after fetching
         * <11..10>     00      Address mode = Increment
         * <9>          1       Terminate Buffer on end of frame
         * <8>          0       Bus Width = 16bits
         * <7..0>       ?       status Bits (Read Only so write as 0)
         *
         *      1111 0010 0000 0000 = 0xf200
         */

        usc_OutDmaReg( info, TDMR, 0xf200 );


        /* DMA Interrupt Control Register (DICR)
         *
         * <15>         1       DMA Interrupt Enable
         * <14>         0       1 = Disable IEO from USC
         * <13>         0       1 = Don't provide vector during IntAck
         * <12>         1       1 = Include status in Vector
         * <10..2>      0       reserved, Must be 0s
         * <1>          0       1 = Rx DMA Interrupt Enabled
         * <0>          0       1 = Tx DMA Interrupt Enabled
         *
         *      1001 0000 0000 0000 = 0x9000
         */

        usc_OutDmaReg( info, DICR, 0x9000 );

        usc_InDmaReg( info, RDMR );             /* clear pending receive DMA IRQ bits */
        usc_InDmaReg( info, TDMR );             /* clear pending transmit DMA IRQ bits */
        usc_OutDmaReg( info, CDIR, 0x0303 );    /* clear IUS and Pending for Tx and Rx */

        /* Channel Control Register (CCR)
         *
         * <15..14>     10      Use 32-bit Tx Control Blocks (TCBs)
         * <13>         0       Trigger Tx on SW Command Disabled
         * <12>         0       Flag Preamble Disabled
         * <11..10>     00      Preamble Length
         * <9..8>       00      Preamble Pattern
         * <7..6>       10      Use 32-bit Rx status Blocks (RSBs)
         * <5>          0       Trigger Rx on SW Command Disabled
         * <4..0>       0       reserved
         *
         *      1000 0000 1000 0000 = 0x8080
         */

        RegValue = 0x8080;

        switch ( info->params.preamble_length ) {
        case HDLC_PREAMBLE_LENGTH_16BITS: RegValue |= BIT10; break;
        case HDLC_PREAMBLE_LENGTH_32BITS: RegValue |= BIT11; break;
        case HDLC_PREAMBLE_LENGTH_64BITS: RegValue |= BIT11 | BIT10; break;
        }

        switch ( info->params.preamble ) {
        case HDLC_PREAMBLE_PATTERN_FLAGS: RegValue |= BIT8 | BIT12; break;
        case HDLC_PREAMBLE_PATTERN_ONES:  RegValue |= BIT8; break;
        case HDLC_PREAMBLE_PATTERN_10:    RegValue |= BIT9; break;
        case HDLC_PREAMBLE_PATTERN_01:    RegValue |= BIT9 | BIT8; break;
        }

        usc_OutReg( info, CCR, RegValue );


        /*
         * Burst/Dwell Control Register
         *
         * <15..8>      0x20    Maximum number of transfers per bus grant
         * <7..0>       0x00    Maximum number of clock cycles per bus grant
         */

        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                /* don't limit bus occupancy on PCI adapter */
                usc_OutDmaReg( info, BDCR, 0x0000 );
        }
        else
                usc_OutDmaReg( info, BDCR, 0x2000 );

        usc_stop_transmitter(info);
        usc_stop_receiver(info);
        
}       /* end of usc_set_sdlc_mode() */

/* usc_enable_loopback()
 *
 * Set the 16C32 for internal loopback mode.
 * The TxCLK and RxCLK signals are generated from the BRG0 and
 * the TxD is looped back to the RxD internally.
 *
 * Arguments:           info    pointer to device instance data
 *                      enable  1 = enable loopback, 0 = disable
 * Return Value:        None
 */
static void usc_enable_loopback(struct mgsl_struct *info, int enable)
{
        if (enable) {
                /* blank external TXD output */
                usc_OutReg(info,IOCR,usc_InReg(info,IOCR) | (BIT7 | BIT6));
        
                /* Clock mode Control Register (CMCR)
                 *
                 * <15..14>     00      counter 1 Disabled
                 * <13..12>     00      counter 0 Disabled
                 * <11..10>     11      BRG1 Input is TxC Pin
                 * <9..8>       11      BRG0 Input is TxC Pin
                 * <7..6>       01      DPLL Input is BRG1 Output
                 * <5..3>       100     TxCLK comes from BRG0
                 * <2..0>       100     RxCLK comes from BRG0
                 *
                 * 0000 1111 0110 0100 = 0x0f64
                 */

                usc_OutReg( info, CMCR, 0x0f64 );

                /* Write 16-bit Time Constant for BRG0 */
                /* use clock speed if available, otherwise use 8 for diagnostics */
                if (info->params.clock_speed) {
                        if (info->bus_type == MGSL_BUS_TYPE_PCI)
                                usc_OutReg(info, TC0R, (u16)((11059200/info->params.clock_speed)-1));
                        else
                                usc_OutReg(info, TC0R, (u16)((14745600/info->params.clock_speed)-1));
                } else
                        usc_OutReg(info, TC0R, (u16)8);

                /* Hardware Configuration Register (HCR) Clear Bit 1, BRG0
                   mode = Continuous Set Bit 0 to enable BRG0.  */
                usc_OutReg( info, HCR, (u16)((usc_InReg( info, HCR ) & ~BIT1) | BIT0) );

                /* Input/Output Control Reg, <2..0> = 100, Drive RxC pin with BRG0 */
                usc_OutReg(info, IOCR, (u16)((usc_InReg(info, IOCR) & 0xfff8) | 0x0004));

                /* set Internal Data loopback mode */
                info->loopback_bits = 0x300;
                outw( 0x0300, info->io_base + CCAR );
        } else {
                /* enable external TXD output */
                usc_OutReg(info,IOCR,usc_InReg(info,IOCR) & ~(BIT7 | BIT6));
        
                /* clear Internal Data loopback mode */
                info->loopback_bits = 0;
                outw( 0,info->io_base + CCAR );
        }
        
}       /* end of usc_enable_loopback() */

/* usc_enable_aux_clock()
 *
 * Enabled the AUX clock output at the specified frequency.
 *
 * Arguments:
 *
 *      info            pointer to device extension
 *      data_rate       data rate of clock in bits per second
 *                      A data rate of 0 disables the AUX clock.
 *
 * Return Value:        None
 */
static void usc_enable_aux_clock( struct mgsl_struct *info, u32 data_rate )
{
        u32 XtalSpeed;
        u16 Tc;

        if ( data_rate ) {
                if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                        XtalSpeed = 11059200;
                else
                        XtalSpeed = 14745600;


                /* Tc = (Xtal/Speed) - 1 */
                /* If twice the remainder of (Xtal/Speed) is greater than Speed */
                /* then rounding up gives a more precise time constant. Instead */
                /* of rounding up and then subtracting 1 we just don't subtract */
                /* the one in this case. */


                Tc = (u16)(XtalSpeed/data_rate);
                if ( !(((XtalSpeed % data_rate) * 2) / data_rate) )
                        Tc--;

                /* Write 16-bit Time Constant for BRG0 */
                usc_OutReg( info, TC0R, Tc );

                /*
                 * Hardware Configuration Register (HCR)
                 * Clear Bit 1, BRG0 mode = Continuous
                 * Set Bit 0 to enable BRG0.
                 */

                usc_OutReg( info, HCR, (u16)((usc_InReg( info, HCR ) & ~BIT1) | BIT0) );

                /* Input/Output Control Reg, <2..0> = 100, Drive RxC pin with BRG0 */
                usc_OutReg( info, IOCR, (u16)((usc_InReg(info, IOCR) & 0xfff8) | 0x0004) );
        } else {
                /* data rate == 0 so turn off BRG0 */
                usc_OutReg( info, HCR, (u16)(usc_InReg( info, HCR ) & ~BIT0) );
        }

}       /* end of usc_enable_aux_clock() */

/*
 *
 * usc_process_rxoverrun_sync()
 *
 *              This function processes a receive overrun by resetting the
 *              receive DMA buffers and issuing a Purge Rx FIFO command
 *              to allow the receiver to continue receiving.
 *
 * Arguments:
 *
 *      info            pointer to device extension
 *
 * Return Value: None
 */
static void usc_process_rxoverrun_sync( struct mgsl_struct *info )
{
        int start_index;
        int end_index;
        int frame_start_index;
        bool start_of_frame_found = false;
        bool end_of_frame_found = false;
        bool reprogram_dma = false;

        DMABUFFERENTRY *buffer_list = info->rx_buffer_list;
        u32 phys_addr;

        usc_DmaCmd( info, DmaCmd_PauseRxChannel );
        usc_RCmd( info, RCmd_EnterHuntmode );
        usc_RTCmd( info, RTCmd_PurgeRxFifo );

        /* CurrentRxBuffer points to the 1st buffer of the next */
        /* possibly available receive frame. */
        
        frame_start_index = start_index = end_index = info->current_rx_buffer;

        /* Search for an unfinished string of buffers. This means */
        /* that a receive frame started (at least one buffer with */
        /* count set to zero) but there is no terminiting buffer */
        /* (status set to non-zero). */

        while( !buffer_list[end_index].count )
        {
                /* Count field has been reset to zero by 16C32. */
                /* This buffer is currently in use. */

                if ( !start_of_frame_found )
                {
                        start_of_frame_found = true;
                        frame_start_index = end_index;
                        end_of_frame_found = false;
                }

                if ( buffer_list[end_index].status )
                {
                        /* Status field has been set by 16C32. */
                        /* This is the last buffer of a received frame. */

                        /* We want to leave the buffers for this frame intact. */
                        /* Move on to next possible frame. */

                        start_of_frame_found = false;
                        end_of_frame_found = true;
                }

                /* advance to next buffer entry in linked list */
                end_index++;
                if ( end_index == info->rx_buffer_count )
                        end_index = 0;

                if ( start_index == end_index )
                {
                        /* The entire list has been searched with all Counts == 0 and */
                        /* all Status == 0. The receive buffers are */
                        /* completely screwed, reset all receive buffers! */
                        mgsl_reset_rx_dma_buffers( info );
                        frame_start_index = 0;
                        start_of_frame_found = false;
                        reprogram_dma = true;
                        break;
                }
        }

        if ( start_of_frame_found && !end_of_frame_found )
        {
                /* There is an unfinished string of receive DMA buffers */
                /* as a result of the receiver overrun. */

                /* Reset the buffers for the unfinished frame */
                /* and reprogram the receive DMA controller to start */
                /* at the 1st buffer of unfinished frame. */

                start_index = frame_start_index;

                do
                {
                        *((unsigned long *)&(info->rx_buffer_list[start_index++].count)) = DMABUFFERSIZE;

                        /* Adjust index for wrap around. */
                        if ( start_index == info->rx_buffer_count )
                                start_index = 0;

                } while( start_index != end_index );

                reprogram_dma = true;
        }

        if ( reprogram_dma )
        {
                usc_UnlatchRxstatusBits(info,RXSTATUS_ALL);
                usc_ClearIrqPendingBits(info, RECEIVE_DATA|RECEIVE_STATUS);
                usc_UnlatchRxstatusBits(info, RECEIVE_DATA|RECEIVE_STATUS);
                
                usc_EnableReceiver(info,DISABLE_UNCONDITIONAL);
                
                /* This empties the receive FIFO and loads the RCC with RCLR */
                usc_OutReg( info, CCSR, (u16)(usc_InReg(info,CCSR) | BIT13) );

                /* program 16C32 with physical address of 1st DMA buffer entry */
                phys_addr = info->rx_buffer_list[frame_start_index].phys_entry;
                usc_OutDmaReg( info, NRARL, (u16)phys_addr );
                usc_OutDmaReg( info, NRARU, (u16)(phys_addr >> 16) );

                usc_UnlatchRxstatusBits( info, RXSTATUS_ALL );
                usc_ClearIrqPendingBits( info, RECEIVE_DATA | RECEIVE_STATUS );
                usc_EnableInterrupts( info, RECEIVE_STATUS );

                /* 1. Arm End of Buffer (EOB) Receive DMA Interrupt (BIT2 of RDIAR) */
                /* 2. Enable Receive DMA Interrupts (BIT1 of DICR) */

                usc_OutDmaReg( info, RDIAR, BIT3 | BIT2 );
                usc_OutDmaReg( info, DICR, (u16)(usc_InDmaReg(info,DICR) | BIT1) );
                usc_DmaCmd( info, DmaCmd_InitRxChannel );
                if ( info->params.flags & HDLC_FLAG_AUTO_DCD )
                        usc_EnableReceiver(info,ENABLE_AUTO_DCD);
                else
                        usc_EnableReceiver(info,ENABLE_UNCONDITIONAL);
        }
        else
        {
                /* This empties the receive FIFO and loads the RCC with RCLR */
                usc_OutReg( info, CCSR, (u16)(usc_InReg(info,CCSR) | BIT13) );
                usc_RTCmd( info, RTCmd_PurgeRxFifo );
        }

}       /* end of usc_process_rxoverrun_sync() */

/* usc_stop_receiver()
 *
 *      Disable USC receiver
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_stop_receiver( struct mgsl_struct *info )
{
        if (debug_level >= DEBUG_LEVEL_ISR)
                printk("%s(%d):usc_stop_receiver(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        /* Disable receive DMA channel. */
        /* This also disables receive DMA channel interrupts */
        usc_DmaCmd( info, DmaCmd_ResetRxChannel );

        usc_UnlatchRxstatusBits( info, RXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, RECEIVE_DATA | RECEIVE_STATUS );
        usc_DisableInterrupts( info, RECEIVE_DATA | RECEIVE_STATUS );

        usc_EnableReceiver(info,DISABLE_UNCONDITIONAL);

        /* This empties the receive FIFO and loads the RCC with RCLR */
        usc_OutReg( info, CCSR, (u16)(usc_InReg(info,CCSR) | BIT13) );
        usc_RTCmd( info, RTCmd_PurgeRxFifo );

        info->rx_enabled = false;
        info->rx_overflow = false;
        info->rx_rcc_underrun = false;
        
}       /* end of stop_receiver() */

/* usc_start_receiver()
 *
 *      Enable the USC receiver 
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_start_receiver( struct mgsl_struct *info )
{
        u32 phys_addr;
        
        if (debug_level >= DEBUG_LEVEL_ISR)
                printk("%s(%d):usc_start_receiver(%s)\n",
                         __FILE__,__LINE__, info->device_name );

        mgsl_reset_rx_dma_buffers( info );
        usc_stop_receiver( info );

        usc_OutReg( info, CCSR, (u16)(usc_InReg(info,CCSR) | BIT13) );
        usc_RTCmd( info, RTCmd_PurgeRxFifo );

        if ( info->params.mode == MGSL_MODE_HDLC ||
                info->params.mode == MGSL_MODE_RAW ) {
                /* DMA mode Transfers */
                /* Program the DMA controller. */
                /* Enable the DMA controller end of buffer interrupt. */

                /* program 16C32 with physical address of 1st DMA buffer entry */
                phys_addr = info->rx_buffer_list[0].phys_entry;
                usc_OutDmaReg( info, NRARL, (u16)phys_addr );
                usc_OutDmaReg( info, NRARU, (u16)(phys_addr >> 16) );

                usc_UnlatchRxstatusBits( info, RXSTATUS_ALL );
                usc_ClearIrqPendingBits( info, RECEIVE_DATA | RECEIVE_STATUS );
                usc_EnableInterrupts( info, RECEIVE_STATUS );

                /* 1. Arm End of Buffer (EOB) Receive DMA Interrupt (BIT2 of RDIAR) */
                /* 2. Enable Receive DMA Interrupts (BIT1 of DICR) */

                usc_OutDmaReg( info, RDIAR, BIT3 | BIT2 );
                usc_OutDmaReg( info, DICR, (u16)(usc_InDmaReg(info,DICR) | BIT1) );
                usc_DmaCmd( info, DmaCmd_InitRxChannel );
                if ( info->params.flags & HDLC_FLAG_AUTO_DCD )
                        usc_EnableReceiver(info,ENABLE_AUTO_DCD);
                else
                        usc_EnableReceiver(info,ENABLE_UNCONDITIONAL);
        } else {
                usc_UnlatchRxstatusBits(info, RXSTATUS_ALL);
                usc_ClearIrqPendingBits(info, RECEIVE_DATA | RECEIVE_STATUS);
                usc_EnableInterrupts(info, RECEIVE_DATA);

                usc_RTCmd( info, RTCmd_PurgeRxFifo );
                usc_RCmd( info, RCmd_EnterHuntmode );

                usc_EnableReceiver(info,ENABLE_UNCONDITIONAL);
        }

        usc_OutReg( info, CCSR, 0x1020 );

        info->rx_enabled = true;

}       /* end of usc_start_receiver() */

/* usc_start_transmitter()
 *
 *      Enable the USC transmitter and send a transmit frame if
 *      one is loaded in the DMA buffers.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_start_transmitter( struct mgsl_struct *info )
{
        u32 phys_addr;
        unsigned int FrameSize;

        if (debug_level >= DEBUG_LEVEL_ISR)
                printk("%s(%d):usc_start_transmitter(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        if ( info->xmit_cnt ) {

                /* If auto RTS enabled and RTS is inactive, then assert */
                /* RTS and set a flag indicating that the driver should */
                /* negate RTS when the transmission completes. */

                info->drop_rts_on_tx_done = false;

                if ( info->params.flags & HDLC_FLAG_AUTO_RTS ) {
                        usc_get_serial_signals( info );
                        if ( !(info->serial_signals & SerialSignal_RTS) ) {
                                info->serial_signals |= SerialSignal_RTS;
                                usc_set_serial_signals( info );
                                info->drop_rts_on_tx_done = true;
                        }
                }


                if ( info->params.mode == MGSL_MODE_ASYNC ) {
                        if ( !info->tx_active ) {
                                usc_UnlatchTxstatusBits(info, TXSTATUS_ALL);
                                usc_ClearIrqPendingBits(info, TRANSMIT_STATUS + TRANSMIT_DATA);
                                usc_EnableInterrupts(info, TRANSMIT_DATA);
                                usc_load_txfifo(info);
                        }
                } else {
                        /* Disable transmit DMA controller while programming. */
                        usc_DmaCmd( info, DmaCmd_ResetTxChannel );
                        
                        /* Transmit DMA buffer is loaded, so program USC */
                        /* to send the frame contained in the buffers.   */

                        FrameSize = info->tx_buffer_list[info->start_tx_dma_buffer].rcc;

                        /* if operating in Raw sync mode, reset the rcc component
                         * of the tx dma buffer entry, otherwise, the serial controller
                         * will send a closing sync char after this count.
                         */
                        if ( info->params.mode == MGSL_MODE_RAW )
                                info->tx_buffer_list[info->start_tx_dma_buffer].rcc = 0;

                        /* Program the Transmit Character Length Register (TCLR) */
                        /* and clear FIFO (TCC is loaded with TCLR on FIFO clear) */
                        usc_OutReg( info, TCLR, (u16)FrameSize );

                        usc_RTCmd( info, RTCmd_PurgeTxFifo );

                        /* Program the address of the 1st DMA Buffer Entry in linked list */
                        phys_addr = info->tx_buffer_list[info->start_tx_dma_buffer].phys_entry;
                        usc_OutDmaReg( info, NTARL, (u16)phys_addr );
                        usc_OutDmaReg( info, NTARU, (u16)(phys_addr >> 16) );

                        usc_UnlatchTxstatusBits( info, TXSTATUS_ALL );
                        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS );
                        usc_EnableInterrupts( info, TRANSMIT_STATUS );

                        if ( info->params.mode == MGSL_MODE_RAW &&
                                        info->num_tx_dma_buffers > 1 ) {
                           /* When running external sync mode, attempt to 'stream' transmit  */
                           /* by filling tx dma buffers as they become available. To do this */
                           /* we need to enable Tx DMA EOB Status interrupts :               */
                           /*                                                                */
                           /* 1. Arm End of Buffer (EOB) Transmit DMA Interrupt (BIT2 of TDIAR) */
                           /* 2. Enable Transmit DMA Interrupts (BIT0 of DICR) */

                           usc_OutDmaReg( info, TDIAR, BIT2|BIT3 );
                           usc_OutDmaReg( info, DICR, (u16)(usc_InDmaReg(info,DICR) | BIT0) );
                        }

                        /* Initialize Transmit DMA Channel */
                        usc_DmaCmd( info, DmaCmd_InitTxChannel );
                        
                        usc_TCmd( info, TCmd_SendFrame );
                        
                        mod_timer(&info->tx_timer, jiffies +
                                        msecs_to_jiffies(5000));
                }
                info->tx_active = true;
        }

        if ( !info->tx_enabled ) {
                info->tx_enabled = true;
                if ( info->params.flags & HDLC_FLAG_AUTO_CTS )
                        usc_EnableTransmitter(info,ENABLE_AUTO_CTS);
                else
                        usc_EnableTransmitter(info,ENABLE_UNCONDITIONAL);
        }

}       /* end of usc_start_transmitter() */

/* usc_stop_transmitter()
 *
 *      Stops the transmitter and DMA
 *
 * Arguments:           info    pointer to device isntance data
 * Return Value:        None
 */
static void usc_stop_transmitter( struct mgsl_struct *info )
{
        if (debug_level >= DEBUG_LEVEL_ISR)
                printk("%s(%d):usc_stop_transmitter(%s)\n",
                         __FILE__,__LINE__, info->device_name );
                         
        del_timer(&info->tx_timer);     
                         
        usc_UnlatchTxstatusBits( info, TXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS + TRANSMIT_DATA );
        usc_DisableInterrupts( info, TRANSMIT_STATUS + TRANSMIT_DATA );

        usc_EnableTransmitter(info,DISABLE_UNCONDITIONAL);
        usc_DmaCmd( info, DmaCmd_ResetTxChannel );
        usc_RTCmd( info, RTCmd_PurgeTxFifo );

        info->tx_enabled = false;
        info->tx_active = false;

}       /* end of usc_stop_transmitter() */

/* usc_load_txfifo()
 *
 *      Fill the transmit FIFO until the FIFO is full or
 *      there is no more data to load.
 *
 * Arguments:           info    pointer to device extension (instance data)
 * Return Value:        None
 */
static void usc_load_txfifo( struct mgsl_struct *info )
{
        int Fifocount;
        u8 TwoBytes[2];
        
        if ( !info->xmit_cnt && !info->x_char )
                return; 
                
        /* Select transmit FIFO status readback in TICR */
        usc_TCmd( info, TCmd_SelectTicrTxFifostatus );

        /* load the Transmit FIFO until FIFOs full or all data sent */

        while( (Fifocount = usc_InReg(info, TICR) >> 8) && info->xmit_cnt ) {
                /* there is more space in the transmit FIFO and */
                /* there is more data in transmit buffer */

                if ( (info->xmit_cnt > 1) && (Fifocount > 1) && !info->x_char ) {
                        /* write a 16-bit word from transmit buffer to 16C32 */
                                
                        TwoBytes[0] = info->xmit_buf[info->xmit_tail++];
                        info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                        TwoBytes[1] = info->xmit_buf[info->xmit_tail++];
                        info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                        
                        outw( *((u16 *)TwoBytes), info->io_base + DATAREG);
                                
                        info->xmit_cnt -= 2;
                        info->icount.tx += 2;
                } else {
                        /* only 1 byte left to transmit or 1 FIFO slot left */
                        
                        outw( (inw( info->io_base + CCAR) & 0x0780) | (TDR+LSBONLY),
                                info->io_base + CCAR );
                        
                        if (info->x_char) {
                                /* transmit pending high priority char */
                                outw( info->x_char,info->io_base + CCAR );
                                info->x_char = 0;
                        } else {
                                outw( info->xmit_buf[info->xmit_tail++],info->io_base + CCAR );
                                info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                                info->xmit_cnt--;
                        }
                        info->icount.tx++;
                }
        }

}       /* end of usc_load_txfifo() */

/* usc_reset()
 *
 *      Reset the adapter to a known state and prepare it for further use.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_reset( struct mgsl_struct *info )
{
        if ( info->bus_type == MGSL_BUS_TYPE_PCI ) {
                int i;
                u32 readval;

                /* Set BIT30 of Misc Control Register */
                /* (Local Control Register 0x50) to force reset of USC. */

                volatile u32 *MiscCtrl = (u32 *)(info->lcr_base + 0x50);
                u32 *LCR0BRDR = (u32 *)(info->lcr_base + 0x28);

                info->misc_ctrl_value |= BIT30;
                *MiscCtrl = info->misc_ctrl_value;

                /*
                 * Force at least 170ns delay before clearing 
                 * reset bit. Each read from LCR takes at least 
                 * 30ns so 10 times for 300ns to be safe.
                 */
                for(i=0;i<10;i++)
                        readval = *MiscCtrl;

                info->misc_ctrl_value &= ~BIT30;
                *MiscCtrl = info->misc_ctrl_value;

                *LCR0BRDR = BUS_DESCRIPTOR(
                        1,              // Write Strobe Hold (0-3)
                        2,              // Write Strobe Delay (0-3)
                        2,              // Read Strobe Delay  (0-3)
                        0,              // NWDD (Write data-data) (0-3)
                        4,              // NWAD (Write Addr-data) (0-31)
                        0,              // NXDA (Read/Write Data-Addr) (0-3)
                        0,              // NRDD (Read Data-Data) (0-3)
                        5               // NRAD (Read Addr-Data) (0-31)
                        );
        } else {
                /* do HW reset */
                outb( 0,info->io_base + 8 );
        }

        info->mbre_bit = 0;
        info->loopback_bits = 0;
        info->usc_idle_mode = 0;

        /*
         * Program the Bus Configuration Register (BCR)
         *
         * <15>         0       Don't use separate address
         * <14..6>      0       reserved
         * <5..4>       00      IAckmode = Default, don't care
         * <3>          1       Bus Request Totem Pole output
         * <2>          1       Use 16 Bit data bus
         * <1>          0       IRQ Totem Pole output
         * <0>          0       Don't Shift Right Addr
         *
         * 0000 0000 0000 1100 = 0x000c
         *
         * By writing to io_base + SDPIN the Wait/Ack pin is
         * programmed to work as a Wait pin.
         */
        
        outw( 0x000c,info->io_base + SDPIN );


        outw( 0,info->io_base );
        outw( 0,info->io_base + CCAR );

        /* select little endian byte ordering */
        usc_RTCmd( info, RTCmd_SelectLittleEndian );


        /* Port Control Register (PCR)
         *
         * <15..14>     11      Port 7 is Output (~DMAEN, Bit 14 : 0 = Enabled)
         * <13..12>     11      Port 6 is Output (~INTEN, Bit 12 : 0 = Enabled)
         * <11..10>     00      Port 5 is Input (No Connect, Don't Care)
         * <9..8>       00      Port 4 is Input (No Connect, Don't Care)
         * <7..6>       11      Port 3 is Output (~RTS, Bit 6 : 0 = Enabled )
         * <5..4>       11      Port 2 is Output (~DTR, Bit 4 : 0 = Enabled )
         * <3..2>       01      Port 1 is Input (Dedicated RxC)
         * <1..0>       01      Port 0 is Input (Dedicated TxC)
         *
         *      1111 0000 1111 0101 = 0xf0f5
         */

        usc_OutReg( info, PCR, 0xf0f5 );


        /*
         * Input/Output Control Register
         *
         * <15..14>     00      CTS is active low input
         * <13..12>     00      DCD is active low input
         * <11..10>     00      TxREQ pin is input (DSR)
         * <9..8>       00      RxREQ pin is input (RI)
         * <7..6>       00      TxD is output (Transmit Data)
         * <5..3>       000     TxC Pin in Input (14.7456MHz Clock)
         * <2..0>       100     RxC is Output (drive with BRG0)
         *
         *      0000 0000 0000 0100 = 0x0004
         */

        usc_OutReg( info, IOCR, 0x0004 );

}       /* end of usc_reset() */

/* usc_set_async_mode()
 *
 *      Program adapter for asynchronous communications.
 *
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void usc_set_async_mode( struct mgsl_struct *info )
{
        u16 RegValue;

        /* disable interrupts while programming USC */
        usc_DisableMasterIrqBit( info );

        outw( 0, info->io_base );                       /* clear Master Bus Enable (DCAR) */
        usc_DmaCmd( info, DmaCmd_ResetAllChannels );    /* disable both DMA channels */

        usc_loopback_frame( info );

        /* Channel mode Register (CMR)
         *
         * <15..14>     00      Tx Sub modes, 00 = 1 Stop Bit
         * <13..12>     00                    00 = 16X Clock
         * <11..8>      0000    Transmitter mode = Asynchronous
         * <7..6>       00      reserved?
         * <5..4>       00      Rx Sub modes, 00 = 16X Clock
         * <3..0>       0000    Receiver mode = Asynchronous
         *
         * 0000 0000 0000 0000 = 0x0
         */

        RegValue = 0;
        if ( info->params.stop_bits != 1 )
                RegValue |= BIT14;
        usc_OutReg( info, CMR, RegValue );

        
        /* Receiver mode Register (RMR)
         *
         * <15..13>     000     encoding = None
         * <12..08>     00000   reserved (Sync Only)
         * <7..6>       00      Even parity
         * <5>          0       parity disabled
         * <4..2>       000     Receive Char Length = 8 bits
         * <1..0>       00      Disable Receiver
         *
         * 0000 0000 0000 0000 = 0x0
         */

        RegValue = 0;

        if ( info->params.data_bits != 8 )
                RegValue |= BIT4 | BIT3 | BIT2;

        if ( info->params.parity != ASYNC_PARITY_NONE ) {
                RegValue |= BIT5;
                if ( info->params.parity != ASYNC_PARITY_ODD )
                        RegValue |= BIT6;
        }

        usc_OutReg( info, RMR, RegValue );


        /* Set IRQ trigger level */

        usc_RCmd( info, RCmd_SelectRicrIntLevel );

        
        /* Receive Interrupt Control Register (RICR)
         *
         * <15..8>      ?               RxFIFO IRQ Request Level
         *
         * Note: For async mode the receive FIFO level must be set
         * to 0 to avoid the situation where the FIFO contains fewer bytes
         * than the trigger level and no more data is expected.
         *
         * <7>          0               Exited Hunt IA (Interrupt Arm)
         * <6>          0               Idle Received IA
         * <5>          0               Break/Abort IA
         * <4>          0               Rx Bound IA
         * <3>          0               Queued status reflects oldest byte in FIFO
         * <2>          0               Abort/PE IA
         * <1>          0               Rx Overrun IA
         * <0>          0               Select TC0 value for readback
         *
         * 0000 0000 0100 0000 = 0x0000 + (FIFOLEVEL in MSB)
         */
        
        usc_OutReg( info, RICR, 0x0000 );

        usc_UnlatchRxstatusBits( info, RXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, RECEIVE_STATUS );

        
        /* Transmit mode Register (TMR)
         *
         * <15..13>     000     encoding = None
         * <12..08>     00000   reserved (Sync Only)
         * <7..6>       00      Transmit parity Even
         * <5>          0       Transmit parity Disabled
         * <4..2>       000     Tx Char Length = 8 bits
         * <1..0>       00      Disable Transmitter
         *
         * 0000 0000 0000 0000 = 0x0
         */

        RegValue = 0;

        if ( info->params.data_bits != 8 )
                RegValue |= BIT4 | BIT3 | BIT2;

        if ( info->params.parity != ASYNC_PARITY_NONE ) {
                RegValue |= BIT5;
                if ( info->params.parity != ASYNC_PARITY_ODD )
                        RegValue |= BIT6;
        }

        usc_OutReg( info, TMR, RegValue );

        usc_set_txidle( info );


        /* Set IRQ trigger level */

        usc_TCmd( info, TCmd_SelectTicrIntLevel );

        
        /* Transmit Interrupt Control Register (TICR)
         *
         * <15..8>      ?       Transmit FIFO IRQ Level
         * <7>          0       Present IA (Interrupt Arm)
         * <6>          1       Idle Sent IA
         * <5>          0       Abort Sent IA
         * <4>          0       EOF/EOM Sent IA
         * <3>          0       CRC Sent IA
         * <2>          0       1 = Wait for SW Trigger to Start Frame
         * <1>          0       Tx Underrun IA
         * <0>          0       TC0 constant on read back
         *
         *      0000 0000 0100 0000 = 0x0040
         */

        usc_OutReg( info, TICR, 0x1f40 );

        usc_UnlatchTxstatusBits( info, TXSTATUS_ALL );
        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS );

        usc_enable_async_clock( info, info->params.data_rate );

        
        /* Channel Control/status Register (CCSR)
         *
         * <15>         X       RCC FIFO Overflow status (RO)
         * <14>         X       RCC FIFO Not Empty status (RO)
         * <13>         0       1 = Clear RCC FIFO (WO)
         * <12>         X       DPLL in Sync status (RO)
         * <11>         X       DPLL 2 Missed Clocks status (RO)
         * <10>         X       DPLL 1 Missed Clock status (RO)
         * <9..8>       00      DPLL Resync on rising and falling edges (RW)
         * <7>          X       SDLC Loop On status (RO)
         * <6>          X       SDLC Loop Send status (RO)
         * <5>          1       Bypass counters for TxClk and RxClk (RW)
         * <4..2>       000     Last Char of SDLC frame has 8 bits (RW)
         * <1..0>       00      reserved
         *
         *      0000 0000 0010 0000 = 0x0020
         */
        
        usc_OutReg( info, CCSR, 0x0020 );

        usc_DisableInterrupts( info, TRANSMIT_STATUS + TRANSMIT_DATA +
                              RECEIVE_DATA + RECEIVE_STATUS );

        usc_ClearIrqPendingBits( info, TRANSMIT_STATUS + TRANSMIT_DATA +
                                RECEIVE_DATA + RECEIVE_STATUS );

        usc_EnableMasterIrqBit( info );

        if (info->bus_type == MGSL_BUS_TYPE_ISA) {
                /* Enable INTEN (Port 6, Bit12) */
                /* This connects the IRQ request signal to the ISA bus */
                usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT13) & ~BIT12));
        }

        if (info->params.loopback) {
                info->loopback_bits = 0x300;
                outw(0x0300, info->io_base + CCAR);
        }

}       /* end of usc_set_async_mode() */

/* usc_loopback_frame()
 *
 *      Loop back a small (2 byte) dummy SDLC frame.
 *      Interrupts and DMA are NOT used. The purpose of this is to
 *      clear any 'stale' status info left over from running in async mode.
 *
 *      The 16C32 shows the strange behaviour of marking the 1st
 *      received SDLC frame with a CRC error even when there is no
 *      CRC error. To get around this a small dummy from of 2 bytes
 *      is looped back when switching from async to sync mode.
 *
 * Arguments:           info            pointer to device instance data
 * Return Value:        None
 */
static void usc_loopback_frame( struct mgsl_struct *info )
{
        int i;
        unsigned long oldmode = info->params.mode;

        info->params.mode = MGSL_MODE_HDLC;
        
        usc_DisableMasterIrqBit( info );

        usc_set_sdlc_mode( info );
        usc_enable_loopback( info, 1 );

        /* Write 16-bit Time Constant for BRG0 */
        usc_OutReg( info, TC0R, 0 );
        
        /* Channel Control Register (CCR)
         *
         * <15..14>     00      Don't use 32-bit Tx Control Blocks (TCBs)
         * <13>         0       Trigger Tx on SW Command Disabled
         * <12>         0       Flag Preamble Disabled
         * <11..10>     00      Preamble Length = 8-Bits
         * <9..8>       01      Preamble Pattern = flags
         * <7..6>       10      Don't use 32-bit Rx status Blocks (RSBs)
         * <5>          0       Trigger Rx on SW Command Disabled
         * <4..0>       0       reserved
         *
         *      0000 0001 0000 0000 = 0x0100
         */

        usc_OutReg( info, CCR, 0x0100 );

        /* SETUP RECEIVER */
        usc_RTCmd( info, RTCmd_PurgeRxFifo );
        usc_EnableReceiver(info,ENABLE_UNCONDITIONAL);

        /* SETUP TRANSMITTER */
        /* Program the Transmit Character Length Register (TCLR) */
        /* and clear FIFO (TCC is loaded with TCLR on FIFO clear) */
        usc_OutReg( info, TCLR, 2 );
        usc_RTCmd( info, RTCmd_PurgeTxFifo );

        /* unlatch Tx status bits, and start transmit channel. */
        usc_UnlatchTxstatusBits(info,TXSTATUS_ALL);
        outw(0,info->io_base + DATAREG);

        /* ENABLE TRANSMITTER */
        usc_TCmd( info, TCmd_SendFrame );
        usc_EnableTransmitter(info,ENABLE_UNCONDITIONAL);
                                                        
        /* WAIT FOR RECEIVE COMPLETE */
        for (i=0 ; i<1000 ; i++)
                if (usc_InReg( info, RCSR ) & (BIT8 | BIT4 | BIT3 | BIT1))
                        break;

        /* clear Internal Data loopback mode */
        usc_enable_loopback(info, 0);

        usc_EnableMasterIrqBit(info);

        info->params.mode = oldmode;

}       /* end of usc_loopback_frame() */

/* usc_set_sync_mode()  Programs the USC for SDLC communications.
 *
 * Arguments:           info    pointer to adapter info structure
 * Return Value:        None
 */
static void usc_set_sync_mode( struct mgsl_struct *info )
{
        usc_loopback_frame( info );
        usc_set_sdlc_mode( info );

        if (info->bus_type == MGSL_BUS_TYPE_ISA) {
                /* Enable INTEN (Port 6, Bit12) */
                /* This connects the IRQ request signal to the ISA bus */
                usc_OutReg(info, PCR, (u16)((usc_InReg(info, PCR) | BIT13) & ~BIT12));
        }

        usc_enable_aux_clock(info, info->params.clock_speed);

        if (info->params.loopback)
                usc_enable_loopback(info,1);

}       /* end of mgsl_set_sync_mode() */

/* usc_set_txidle()     Set the HDLC idle mode for the transmitter.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_set_txidle( struct mgsl_struct *info )
{
        u16 usc_idle_mode = IDLEMODE_FLAGS;

        /* Map API idle mode to USC register bits */

        switch( info->idle_mode ){
        case HDLC_TXIDLE_FLAGS:                 usc_idle_mode = IDLEMODE_FLAGS; break;
        case HDLC_TXIDLE_ALT_ZEROS_ONES:        usc_idle_mode = IDLEMODE_ALT_ONE_ZERO; break;
        case HDLC_TXIDLE_ZEROS:                 usc_idle_mode = IDLEMODE_ZERO; break;
        case HDLC_TXIDLE_ONES:                  usc_idle_mode = IDLEMODE_ONE; break;
        case HDLC_TXIDLE_ALT_MARK_SPACE:        usc_idle_mode = IDLEMODE_ALT_MARK_SPACE; break;
        case HDLC_TXIDLE_SPACE:                 usc_idle_mode = IDLEMODE_SPACE; break;
        case HDLC_TXIDLE_MARK:                  usc_idle_mode = IDLEMODE_MARK; break;
        }

        info->usc_idle_mode = usc_idle_mode;
        //usc_OutReg(info, TCSR, usc_idle_mode);
        info->tcsr_value &= ~IDLEMODE_MASK;     /* clear idle mode bits */
        info->tcsr_value += usc_idle_mode;
        usc_OutReg(info, TCSR, info->tcsr_value);

        /*
         * if SyncLink WAN adapter is running in external sync mode, the
         * transmitter has been set to Monosync in order to try to mimic
         * a true raw outbound bit stream. Monosync still sends an open/close
         * sync char at the start/end of a frame. Try to match those sync
         * patterns to the idle mode set here
         */
        if ( info->params.mode == MGSL_MODE_RAW ) {
                unsigned char syncpat = 0;
                switch( info->idle_mode ) {
                case HDLC_TXIDLE_FLAGS:
                        syncpat = 0x7e;
                        break;
                case HDLC_TXIDLE_ALT_ZEROS_ONES:
                        syncpat = 0x55;
                        break;
                case HDLC_TXIDLE_ZEROS:
                case HDLC_TXIDLE_SPACE:
                        syncpat = 0x00;
                        break;
                case HDLC_TXIDLE_ONES:
                case HDLC_TXIDLE_MARK:
                        syncpat = 0xff;
                        break;
                case HDLC_TXIDLE_ALT_MARK_SPACE:
                        syncpat = 0xaa;
                        break;
                }

                usc_SetTransmitSyncChars(info,syncpat,syncpat);
        }

}       /* end of usc_set_txidle() */

/* usc_get_serial_signals()
 *
 *      Query the adapter for the state of the V24 status (input) signals.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_get_serial_signals( struct mgsl_struct *info )
{
        u16 status;

        /* clear all serial signals except RTS and DTR */
        info->serial_signals &= SerialSignal_RTS | SerialSignal_DTR;

        /* Read the Misc Interrupt status Register (MISR) to get */
        /* the V24 status signals. */

        status = usc_InReg( info, MISR );

        /* set serial signal bits to reflect MISR */

        if ( status & MISCSTATUS_CTS )
                info->serial_signals |= SerialSignal_CTS;

        if ( status & MISCSTATUS_DCD )
                info->serial_signals |= SerialSignal_DCD;

        if ( status & MISCSTATUS_RI )
                info->serial_signals |= SerialSignal_RI;

        if ( status & MISCSTATUS_DSR )
                info->serial_signals |= SerialSignal_DSR;

}       /* end of usc_get_serial_signals() */

/* usc_set_serial_signals()
 *
 *      Set the state of RTS and DTR based on contents of
 *      serial_signals member of device extension.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void usc_set_serial_signals( struct mgsl_struct *info )
{
        u16 Control;
        unsigned char V24Out = info->serial_signals;

        /* get the current value of the Port Control Register (PCR) */

        Control = usc_InReg( info, PCR );

        if ( V24Out & SerialSignal_RTS )
                Control &= ~(BIT6);
        else
                Control |= BIT6;

        if ( V24Out & SerialSignal_DTR )
                Control &= ~(BIT4);
        else
                Control |= BIT4;

        usc_OutReg( info, PCR, Control );

}       /* end of usc_set_serial_signals() */

/* usc_enable_async_clock()
 *
 *      Enable the async clock at the specified frequency.
 *
 * Arguments:           info            pointer to device instance data
 *                      data_rate       data rate of clock in bps
 *                                      0 disables the AUX clock.
 * Return Value:        None
 */
static void usc_enable_async_clock( struct mgsl_struct *info, u32 data_rate )
{
        if ( data_rate )        {
                /*
                 * Clock mode Control Register (CMCR)
                 * 
                 * <15..14>     00      counter 1 Disabled
                 * <13..12>     00      counter 0 Disabled
                 * <11..10>     11      BRG1 Input is TxC Pin
                 * <9..8>       11      BRG0 Input is TxC Pin
                 * <7..6>       01      DPLL Input is BRG1 Output
                 * <5..3>       100     TxCLK comes from BRG0
                 * <2..0>       100     RxCLK comes from BRG0
                 *
                 * 0000 1111 0110 0100 = 0x0f64
                 */
                
                usc_OutReg( info, CMCR, 0x0f64 );


                /*
                 * Write 16-bit Time Constant for BRG0
                 * Time Constant = (ClkSpeed / data_rate) - 1
                 * ClkSpeed = 921600 (ISA), 691200 (PCI)
                 */

                if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                        usc_OutReg( info, TC0R, (u16)((691200/data_rate) - 1) );
                else
                        usc_OutReg( info, TC0R, (u16)((921600/data_rate) - 1) );

                
                /*
                 * Hardware Configuration Register (HCR)
                 * Clear Bit 1, BRG0 mode = Continuous
                 * Set Bit 0 to enable BRG0.
                 */

                usc_OutReg( info, HCR,
                            (u16)((usc_InReg( info, HCR ) & ~BIT1) | BIT0) );


                /* Input/Output Control Reg, <2..0> = 100, Drive RxC pin with BRG0 */

                usc_OutReg( info, IOCR,
                            (u16)((usc_InReg(info, IOCR) & 0xfff8) | 0x0004) );
        } else {
                /* data rate == 0 so turn off BRG0 */
                usc_OutReg( info, HCR, (u16)(usc_InReg( info, HCR ) & ~BIT0) );
        }

}       /* end of usc_enable_async_clock() */

/*
 * Buffer Structures:
 *
 * Normal memory access uses virtual addresses that can make discontiguous
 * physical memory pages appear to be contiguous in the virtual address
 * space (the processors memory mapping handles the conversions).
 *
 * DMA transfers require physically contiguous memory. This is because
 * the DMA system controller and DMA bus masters deal with memory using
 * only physical addresses.
 *
 * This causes a problem under Windows NT when large DMA buffers are
 * needed. Fragmentation of the nonpaged pool prevents allocations of
 * physically contiguous buffers larger than the PAGE_SIZE.
 *
 * However the 16C32 supports Bus Master Scatter/Gather DMA which
 * allows DMA transfers to physically discontiguous buffers. Information
 * about each data transfer buffer is contained in a memory structure
 * called a 'buffer entry'. A list of buffer entries is maintained
 * to track and control the use of the data transfer buffers.
 *
 * To support this strategy we will allocate sufficient PAGE_SIZE
 * contiguous memory buffers to allow for the total required buffer
 * space.
 *
 * The 16C32 accesses the list of buffer entries using Bus Master
 * DMA. Control information is read from the buffer entries by the
 * 16C32 to control data transfers. status information is written to
 * the buffer entries by the 16C32 to indicate the status of completed
 * transfers.
 *
 * The CPU writes control information to the buffer entries to control
 * the 16C32 and reads status information from the buffer entries to
 * determine information about received and transmitted frames.
 *
 * Because the CPU and 16C32 (adapter) both need simultaneous access
 * to the buffer entries, the buffer entry memory is allocated with
 * HalAllocateCommonBuffer(). This restricts the size of the buffer
 * entry list to PAGE_SIZE.
 *
 * The actual data buffers on the other hand will only be accessed
 * by the CPU or the adapter but not by both simultaneously. This allows
 * Scatter/Gather packet based DMA procedures for using physically
 * discontiguous pages.
 */

/*
 * mgsl_reset_tx_dma_buffers()
 *
 *      Set the count for all transmit buffers to 0 to indicate the
 *      buffer is available for use and set the current buffer to the
 *      first buffer. This effectively makes all buffers free and
 *      discards any data in buffers.
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_reset_tx_dma_buffers( struct mgsl_struct *info )
{
        unsigned int i;

        for ( i = 0; i < info->tx_buffer_count; i++ ) {
                *((unsigned long *)&(info->tx_buffer_list[i].count)) = 0;
        }

        info->current_tx_buffer = 0;
        info->start_tx_dma_buffer = 0;
        info->tx_dma_buffers_used = 0;

        info->get_tx_holding_index = 0;
        info->put_tx_holding_index = 0;
        info->tx_holding_count = 0;

}       /* end of mgsl_reset_tx_dma_buffers() */

/*
 * num_free_tx_dma_buffers()
 *
 *      returns the number of free tx dma buffers available
 *
 * Arguments:           info    pointer to device instance data
 * Return Value:        number of free tx dma buffers
 */
static int num_free_tx_dma_buffers(struct mgsl_struct *info)
{
        return info->tx_buffer_count - info->tx_dma_buffers_used;
}

/*
 * mgsl_reset_rx_dma_buffers()
 * 
 *      Set the count for all receive buffers to DMABUFFERSIZE
 *      and set the current buffer to the first buffer. This effectively
 *      makes all buffers free and discards any data in buffers.
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        None
 */
static void mgsl_reset_rx_dma_buffers( struct mgsl_struct *info )
{
        unsigned int i;

        for ( i = 0; i < info->rx_buffer_count; i++ ) {
                *((unsigned long *)&(info->rx_buffer_list[i].count)) = DMABUFFERSIZE;
//              info->rx_buffer_list[i].count = DMABUFFERSIZE;
//              info->rx_buffer_list[i].status = 0;
        }

        info->current_rx_buffer = 0;

}       /* end of mgsl_reset_rx_dma_buffers() */

/*
 * mgsl_free_rx_frame_buffers()
 * 
 *      Free the receive buffers used by a received SDLC
 *      frame such that the buffers can be reused.
 * 
 * Arguments:
 * 
 *      info                    pointer to device instance data
 *      StartIndex              index of 1st receive buffer of frame
 *      EndIndex                index of last receive buffer of frame
 * 
 * Return Value:        None
 */
static void mgsl_free_rx_frame_buffers( struct mgsl_struct *info, unsigned int StartIndex, unsigned int EndIndex )
{
        bool Done = false;
        DMABUFFERENTRY *pBufEntry;
        unsigned int Index;

        /* Starting with 1st buffer entry of the frame clear the status */
        /* field and set the count field to DMA Buffer Size. */

        Index = StartIndex;

        while( !Done ) {
                pBufEntry = &(info->rx_buffer_list[Index]);

                if ( Index == EndIndex ) {
                        /* This is the last buffer of the frame! */
                        Done = true;
                }

                /* reset current buffer for reuse */
//              pBufEntry->status = 0;
//              pBufEntry->count = DMABUFFERSIZE;
                *((unsigned long *)&(pBufEntry->count)) = DMABUFFERSIZE;

                /* advance to next buffer entry in linked list */
                Index++;
                if ( Index == info->rx_buffer_count )
                        Index = 0;
        }

        /* set current buffer to next buffer after last buffer of frame */
        info->current_rx_buffer = Index;

}       /* end of free_rx_frame_buffers() */

/* mgsl_get_rx_frame()
 * 
 *      This function attempts to return a received SDLC frame from the
 *      receive DMA buffers. Only frames received without errors are returned.
 *
 * Arguments:           info    pointer to device extension
 * Return Value:        true if frame returned, otherwise false
 */
static bool mgsl_get_rx_frame(struct mgsl_struct *info)
{
        unsigned int StartIndex, EndIndex;      /* index of 1st and last buffers of Rx frame */
        unsigned short status;
        DMABUFFERENTRY *pBufEntry;
        unsigned int framesize = 0;
        bool ReturnCode = false;
        unsigned long flags;
        struct tty_struct *tty = info->port.tty;
        bool return_frame = false;
        
        /*
         * current_rx_buffer points to the 1st buffer of the next available
         * receive frame. To find the last buffer of the frame look for
         * a non-zero status field in the buffer entries. (The status
         * field is set by the 16C32 after completing a receive frame.
         */

        StartIndex = EndIndex = info->current_rx_buffer;

        while( !info->rx_buffer_list[EndIndex].status ) {
                /*
                 * If the count field of the buffer entry is non-zero then
                 * this buffer has not been used. (The 16C32 clears the count
                 * field when it starts using the buffer.) If an unused buffer
                 * is encountered then there are no frames available.
                 */

                if ( info->rx_buffer_list[EndIndex].count )
                        goto Cleanup;

                /* advance to next buffer entry in linked list */
                EndIndex++;
                if ( EndIndex == info->rx_buffer_count )
                        EndIndex = 0;

                /* if entire list searched then no frame available */
                if ( EndIndex == StartIndex ) {
                        /* If this occurs then something bad happened,
                         * all buffers have been 'used' but none mark
                         * the end of a frame. Reset buffers and receiver.
                         */

                        if ( info->rx_enabled ){
                                spin_lock_irqsave(&info->irq_spinlock,flags);
                                usc_start_receiver(info);
                                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        }
                        goto Cleanup;
                }
        }


        /* check status of receive frame */
        
        status = info->rx_buffer_list[EndIndex].status;

        if ( status & (RXSTATUS_SHORT_FRAME | RXSTATUS_OVERRUN |
                        RXSTATUS_CRC_ERROR | RXSTATUS_ABORT) ) {
                if ( status & RXSTATUS_SHORT_FRAME )
                        info->icount.rxshort++;
                else if ( status & RXSTATUS_ABORT )
                        info->icount.rxabort++;
                else if ( status & RXSTATUS_OVERRUN )
                        info->icount.rxover++;
                else {
                        info->icount.rxcrc++;
                        if ( info->params.crc_type & HDLC_CRC_RETURN_EX )
                                return_frame = true;
                }
                framesize = 0;
#if SYNCLINK_GENERIC_HDLC
                {
                        info->netdev->stats.rx_errors++;
                        info->netdev->stats.rx_frame_errors++;
                }
#endif
        } else
                return_frame = true;

        if ( return_frame ) {
                /* receive frame has no errors, get frame size.
                 * The frame size is the starting value of the RCC (which was
                 * set to 0xffff) minus the ending value of the RCC (decremented
                 * once for each receive character) minus 2 for the 16-bit CRC.
                 */

                framesize = RCLRVALUE - info->rx_buffer_list[EndIndex].rcc;

                /* adjust frame size for CRC if any */
                if ( info->params.crc_type == HDLC_CRC_16_CCITT )
                        framesize -= 2;
                else if ( info->params.crc_type == HDLC_CRC_32_CCITT )
                        framesize -= 4;         
        }

        if ( debug_level >= DEBUG_LEVEL_BH )
                printk("%s(%d):mgsl_get_rx_frame(%s) status=%04X size=%d\n",
                        __FILE__,__LINE__,info->device_name,status,framesize);
                        
        if ( debug_level >= DEBUG_LEVEL_DATA )
                mgsl_trace_block(info,info->rx_buffer_list[StartIndex].virt_addr,
                        min_t(int, framesize, DMABUFFERSIZE),0);
                
        if (framesize) {
                if ( ( (info->params.crc_type & HDLC_CRC_RETURN_EX) &&
                                ((framesize+1) > info->max_frame_size) ) ||
                        (framesize > info->max_frame_size) )
                        info->icount.rxlong++;
                else {
                        /* copy dma buffer(s) to contiguous intermediate buffer */
                        int copy_count = framesize;
                        int index = StartIndex;
                        unsigned char *ptmp = info->intermediate_rxbuffer;

                        if ( !(status & RXSTATUS_CRC_ERROR))
                                info->icount.rxok++;
                        
                        while(copy_count) {
                                int partial_count;
                                if ( copy_count > DMABUFFERSIZE )
                                        partial_count = DMABUFFERSIZE;
                                else
                                        partial_count = copy_count;
                        
                                pBufEntry = &(info->rx_buffer_list[index]);
                                memcpy( ptmp, pBufEntry->virt_addr, partial_count );
                                ptmp += partial_count;
                                copy_count -= partial_count;
                                
                                if ( ++index == info->rx_buffer_count )
                                        index = 0;
                        }

                        if ( info->params.crc_type & HDLC_CRC_RETURN_EX ) {
                                ++framesize;
                                *ptmp = (status & RXSTATUS_CRC_ERROR ?
                                                RX_CRC_ERROR :
                                                RX_OK);

                                if ( debug_level >= DEBUG_LEVEL_DATA )
                                        printk("%s(%d):mgsl_get_rx_frame(%s) rx frame status=%d\n",
                                                __FILE__,__LINE__,info->device_name,
                                                *ptmp);
                        }

#if SYNCLINK_GENERIC_HDLC
                        if (info->netcount)
                                hdlcdev_rx(info,info->intermediate_rxbuffer,framesize);
                        else
#endif
                                ldisc_receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
                }
        }
        /* Free the buffers used by this frame. */
        mgsl_free_rx_frame_buffers( info, StartIndex, EndIndex );

        ReturnCode = true;

Cleanup:

        if ( info->rx_enabled && info->rx_overflow ) {
                /* The receiver needs to restarted because of 
                 * a receive overflow (buffer or FIFO). If the 
                 * receive buffers are now empty, then restart receiver.
                 */

                if ( !info->rx_buffer_list[EndIndex].status &&
                        info->rx_buffer_list[EndIndex].count ) {
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        usc_start_receiver(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                }
        }

        return ReturnCode;

}       /* end of mgsl_get_rx_frame() */

/* mgsl_get_raw_rx_frame()
 *
 *      This function attempts to return a received frame from the
 *      receive DMA buffers when running in external loop mode. In this mode,
 *      we will return at most one DMABUFFERSIZE frame to the application.
 *      The USC receiver is triggering off of DCD going active to start a new
 *      frame, and DCD going inactive to terminate the frame (similar to
 *      processing a closing flag character).
 *
 *      In this routine, we will return DMABUFFERSIZE "chunks" at a time.
 *      If DCD goes inactive, the last Rx DMA Buffer will have a non-zero
 *      status field and the RCC field will indicate the length of the
 *      entire received frame. We take this RCC field and get the modulus
 *      of RCC and DMABUFFERSIZE to determine if number of bytes in the
 *      last Rx DMA buffer and return that last portion of the frame.
 *
 * Arguments:           info    pointer to device extension
 * Return Value:        true if frame returned, otherwise false
 */
static bool mgsl_get_raw_rx_frame(struct mgsl_struct *info)
{
        unsigned int CurrentIndex, NextIndex;
        unsigned short status;
        DMABUFFERENTRY *pBufEntry;
        unsigned int framesize = 0;
        bool ReturnCode = false;
        unsigned long flags;
        struct tty_struct *tty = info->port.tty;

        /*
         * current_rx_buffer points to the 1st buffer of the next available
         * receive frame. The status field is set by the 16C32 after
         * completing a receive frame. If the status field of this buffer
         * is zero, either the USC is still filling this buffer or this
         * is one of a series of buffers making up a received frame.
         *
         * If the count field of this buffer is zero, the USC is either
         * using this buffer or has used this buffer. Look at the count
         * field of the next buffer. If that next buffer's count is
         * non-zero, the USC is still actively using the current buffer.
         * Otherwise, if the next buffer's count field is zero, the
         * current buffer is complete and the USC is using the next
         * buffer.
         */
        CurrentIndex = NextIndex = info->current_rx_buffer;
        ++NextIndex;
        if ( NextIndex == info->rx_buffer_count )
                NextIndex = 0;

        if ( info->rx_buffer_list[CurrentIndex].status != 0 ||
                (info->rx_buffer_list[CurrentIndex].count == 0 &&
                        info->rx_buffer_list[NextIndex].count == 0)) {
                /*
                 * Either the status field of this dma buffer is non-zero
                 * (indicating the last buffer of a receive frame) or the next
                 * buffer is marked as in use -- implying this buffer is complete
                 * and an intermediate buffer for this received frame.
                 */

                status = info->rx_buffer_list[CurrentIndex].status;

                if ( status & (RXSTATUS_SHORT_FRAME | RXSTATUS_OVERRUN |
                                RXSTATUS_CRC_ERROR | RXSTATUS_ABORT) ) {
                        if ( status & RXSTATUS_SHORT_FRAME )
                                info->icount.rxshort++;
                        else if ( status & RXSTATUS_ABORT )
                                info->icount.rxabort++;
                        else if ( status & RXSTATUS_OVERRUN )
                                info->icount.rxover++;
                        else
                                info->icount.rxcrc++;
                        framesize = 0;
                } else {
                        /*
                         * A receive frame is available, get frame size and status.
                         *
                         * The frame size is the starting value of the RCC (which was
                         * set to 0xffff) minus the ending value of the RCC (decremented
                         * once for each receive character) minus 2 or 4 for the 16-bit
                         * or 32-bit CRC.
                         *
                         * If the status field is zero, this is an intermediate buffer.
                         * It's size is 4K.
                         *
                         * If the DMA Buffer Entry's Status field is non-zero, the
                         * receive operation completed normally (ie: DCD dropped). The
                         * RCC field is valid and holds the received frame size.
                         * It is possible that the RCC field will be zero on a DMA buffer
                         * entry with a non-zero status. This can occur if the total
                         * frame size (number of bytes between the time DCD goes active
                         * to the time DCD goes inactive) exceeds 65535 bytes. In this
                         * case the 16C32 has underrun on the RCC count and appears to
                         * stop updating this counter to let us know the actual received
                         * frame size. If this happens (non-zero status and zero RCC),
                         * simply return the entire RxDMA Buffer
                         */
                        if ( status ) {
                                /*
                                 * In the event that the final RxDMA Buffer is
                                 * terminated with a non-zero status and the RCC
                                 * field is zero, we interpret this as the RCC
                                 * having underflowed (received frame > 65535 bytes).
                                 *
                                 * Signal the event to the user by passing back
                                 * a status of RxStatus_CrcError returning the full
                                 * buffer and let the app figure out what data is
                                 * actually valid
                                 */
                                if ( info->rx_buffer_list[CurrentIndex].rcc )
                                        framesize = RCLRVALUE - info->rx_buffer_list[CurrentIndex].rcc;
                                else
                                        framesize = DMABUFFERSIZE;
                        }
                        else
                                framesize = DMABUFFERSIZE;
                }

                if ( framesize > DMABUFFERSIZE ) {
                        /*
                         * if running in raw sync mode, ISR handler for
                         * End Of Buffer events terminates all buffers at 4K.
                         * If this frame size is said to be >4K, get the
                         * actual number of bytes of the frame in this buffer.
                         */
                        framesize = framesize % DMABUFFERSIZE;
                }


                if ( debug_level >= DEBUG_LEVEL_BH )
                        printk("%s(%d):mgsl_get_raw_rx_frame(%s) status=%04X size=%d\n",
                                __FILE__,__LINE__,info->device_name,status,framesize);

                if ( debug_level >= DEBUG_LEVEL_DATA )
                        mgsl_trace_block(info,info->rx_buffer_list[CurrentIndex].virt_addr,
                                min_t(int, framesize, DMABUFFERSIZE),0);

                if (framesize) {
                        /* copy dma buffer(s) to contiguous intermediate buffer */
                        /* NOTE: we never copy more than DMABUFFERSIZE bytes    */

                        pBufEntry = &(info->rx_buffer_list[CurrentIndex]);
                        memcpy( info->intermediate_rxbuffer, pBufEntry->virt_addr, framesize);
                        info->icount.rxok++;

                        ldisc_receive_buf(tty, info->intermediate_rxbuffer, info->flag_buf, framesize);
                }

                /* Free the buffers used by this frame. */
                mgsl_free_rx_frame_buffers( info, CurrentIndex, CurrentIndex );

                ReturnCode = true;
        }


        if ( info->rx_enabled && info->rx_overflow ) {
                /* The receiver needs to restarted because of
                 * a receive overflow (buffer or FIFO). If the
                 * receive buffers are now empty, then restart receiver.
                 */

                if ( !info->rx_buffer_list[CurrentIndex].status &&
                        info->rx_buffer_list[CurrentIndex].count ) {
                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        usc_start_receiver(info);
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                }
        }

        return ReturnCode;

}       /* end of mgsl_get_raw_rx_frame() */

/* mgsl_load_tx_dma_buffer()
 * 
 *      Load the transmit DMA buffer with the specified data.
 * 
 * Arguments:
 * 
 *      info            pointer to device extension
 *      Buffer          pointer to buffer containing frame to load
 *      BufferSize      size in bytes of frame in Buffer
 * 
 * Return Value:        None
 */
static void mgsl_load_tx_dma_buffer(struct mgsl_struct *info,
                const char *Buffer, unsigned int BufferSize)
{
        unsigned short Copycount;
        unsigned int i = 0;
        DMABUFFERENTRY *pBufEntry;
        
        if ( debug_level >= DEBUG_LEVEL_DATA )
                mgsl_trace_block(info,Buffer, min_t(int, BufferSize, DMABUFFERSIZE), 1);

        if (info->params.flags & HDLC_FLAG_HDLC_LOOPMODE) {
                /* set CMR:13 to start transmit when
                 * next GoAhead (abort) is received
                 */
                info->cmr_value |= BIT13;
        }
                
        /* begin loading the frame in the next available tx dma
         * buffer, remember it's starting location for setting
         * up tx dma operation
         */
        i = info->current_tx_buffer;
        info->start_tx_dma_buffer = i;

        /* Setup the status and RCC (Frame Size) fields of the 1st */
        /* buffer entry in the transmit DMA buffer list. */

        info->tx_buffer_list[i].status = info->cmr_value & 0xf000;
        info->tx_buffer_list[i].rcc    = BufferSize;
        info->tx_buffer_list[i].count  = BufferSize;

        /* Copy frame data from 1st source buffer to the DMA buffers. */
        /* The frame data may span multiple DMA buffers. */

        while( BufferSize ){
                /* Get a pointer to next DMA buffer entry. */
                pBufEntry = &info->tx_buffer_list[i++];
                        
                if ( i == info->tx_buffer_count )
                        i=0;

                /* Calculate the number of bytes that can be copied from */
                /* the source buffer to this DMA buffer. */
                if ( BufferSize > DMABUFFERSIZE )
                        Copycount = DMABUFFERSIZE;
                else
                        Copycount = BufferSize;

                /* Actually copy data from source buffer to DMA buffer. */
                /* Also set the data count for this individual DMA buffer. */
                if ( info->bus_type == MGSL_BUS_TYPE_PCI )
                        mgsl_load_pci_memory(pBufEntry->virt_addr, Buffer,Copycount);
                else
                        memcpy(pBufEntry->virt_addr, Buffer, Copycount);

                pBufEntry->count = Copycount;

                /* Advance source pointer and reduce remaining data count. */
                Buffer += Copycount;
                BufferSize -= Copycount;

                ++info->tx_dma_buffers_used;
        }

        /* remember next available tx dma buffer */
        info->current_tx_buffer = i;

}       /* end of mgsl_load_tx_dma_buffer() */

/*
 * mgsl_register_test()
 * 
 *      Performs a register test of the 16C32.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:                true if test passed, otherwise false
 */
static bool mgsl_register_test( struct mgsl_struct *info )
{
        static unsigned short BitPatterns[] =
                { 0x0000, 0xffff, 0xaaaa, 0x5555, 0x1234, 0x6969, 0x9696, 0x0f0f };
        static unsigned int Patterncount = ARRAY_SIZE(BitPatterns);
        unsigned int i;
        bool rc = true;
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_reset(info);

        /* Verify the reset state of some registers. */

        if ( (usc_InReg( info, SICR ) != 0) ||
                  (usc_InReg( info, IVR  ) != 0) ||
                  (usc_InDmaReg( info, DIVR ) != 0) ){
                rc = false;
        }

        if ( rc ){
                /* Write bit patterns to various registers but do it out of */
                /* sync, then read back and verify values. */

                for ( i = 0 ; i < Patterncount ; i++ ) {
                        usc_OutReg( info, TC0R, BitPatterns[i] );
                        usc_OutReg( info, TC1R, BitPatterns[(i+1)%Patterncount] );
                        usc_OutReg( info, TCLR, BitPatterns[(i+2)%Patterncount] );
                        usc_OutReg( info, RCLR, BitPatterns[(i+3)%Patterncount] );
                        usc_OutReg( info, RSR,  BitPatterns[(i+4)%Patterncount] );
                        usc_OutDmaReg( info, TBCR, BitPatterns[(i+5)%Patterncount] );

                        if ( (usc_InReg( info, TC0R ) != BitPatterns[i]) ||
                                  (usc_InReg( info, TC1R ) != BitPatterns[(i+1)%Patterncount]) ||
                                  (usc_InReg( info, TCLR ) != BitPatterns[(i+2)%Patterncount]) ||
                                  (usc_InReg( info, RCLR ) != BitPatterns[(i+3)%Patterncount]) ||
                                  (usc_InReg( info, RSR )  != BitPatterns[(i+4)%Patterncount]) ||
                                  (usc_InDmaReg( info, TBCR ) != BitPatterns[(i+5)%Patterncount]) ){
                                rc = false;
                                break;
                        }
                }
        }

        usc_reset(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        return rc;

}       /* end of mgsl_register_test() */

/* mgsl_irq_test()      Perform interrupt test of the 16C32.
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        true if test passed, otherwise false
 */
static bool mgsl_irq_test( struct mgsl_struct *info )
{
        unsigned long EndTime;
        unsigned long flags;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_reset(info);

        /*
         * Setup 16C32 to interrupt on TxC pin (14MHz clock) transition. 
         * The ISR sets irq_occurred to true.
         */

        info->irq_occurred = false;

        /* Enable INTEN gate for ISA adapter (Port 6, Bit12) */
        /* Enable INTEN (Port 6, Bit12) */
        /* This connects the IRQ request signal to the ISA bus */
        /* on the ISA adapter. This has no effect for the PCI adapter */
        usc_OutReg( info, PCR, (unsigned short)((usc_InReg(info, PCR) | BIT13) & ~BIT12) );

        usc_EnableMasterIrqBit(info);
        usc_EnableInterrupts(info, IO_PIN);
        usc_ClearIrqPendingBits(info, IO_PIN);
        
        usc_UnlatchIostatusBits(info, MISCSTATUS_TXC_LATCHED);
        usc_EnableStatusIrqs(info, SICR_TXC_ACTIVE + SICR_TXC_INACTIVE);

        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        EndTime=100;
        while( EndTime-- && !info->irq_occurred ) {
                msleep_interruptible(10);
        }
        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_reset(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
        return info->irq_occurred;

}       /* end of mgsl_irq_test() */

/* mgsl_dma_test()
 * 
 *      Perform a DMA test of the 16C32. A small frame is
 *      transmitted via DMA from a transmit buffer to a receive buffer
 *      using single buffer DMA mode.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        true if test passed, otherwise false
 */
static bool mgsl_dma_test( struct mgsl_struct *info )
{
        unsigned short FifoLevel;
        unsigned long phys_addr;
        unsigned int FrameSize;
        unsigned int i;
        char *TmpPtr;
        bool rc = true;
        unsigned short status=0;
        unsigned long EndTime;
        unsigned long flags;
        MGSL_PARAMS tmp_params;

        /* save current port options */
        memcpy(&tmp_params,&info->params,sizeof(MGSL_PARAMS));
        /* load default port options */
        memcpy(&info->params,&default_params,sizeof(MGSL_PARAMS));
        
#define TESTFRAMESIZE 40

        spin_lock_irqsave(&info->irq_spinlock,flags);
        
        /* setup 16C32 for SDLC DMA transfer mode */

        usc_reset(info);
        usc_set_sdlc_mode(info);
        usc_enable_loopback(info,1);
        
        /* Reprogram the RDMR so that the 16C32 does NOT clear the count
         * field of the buffer entry after fetching buffer address. This
         * way we can detect a DMA failure for a DMA read (which should be
         * non-destructive to system memory) before we try and write to
         * memory (where a failure could corrupt system memory).
         */

        /* Receive DMA mode Register (RDMR)
         * 
         * <15..14>     11      DMA mode = Linked List Buffer mode
         * <13>         1       RSBinA/L = store Rx status Block in List entry
         * <12>         0       1 = Clear count of List Entry after fetching
         * <11..10>     00      Address mode = Increment
         * <9>          1       Terminate Buffer on RxBound
         * <8>          0       Bus Width = 16bits
         * <7..0>               ?       status Bits (write as 0s)
         * 
         * 1110 0010 0000 0000 = 0xe200
         */

        usc_OutDmaReg( info, RDMR, 0xe200 );
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);


        /* SETUP TRANSMIT AND RECEIVE DMA BUFFERS */

        FrameSize = TESTFRAMESIZE;

        /* setup 1st transmit buffer entry: */
        /* with frame size and transmit control word */

        info->tx_buffer_list[0].count  = FrameSize;
        info->tx_buffer_list[0].rcc    = FrameSize;
        info->tx_buffer_list[0].status = 0x4000;

        /* build a transmit frame in 1st transmit DMA buffer */

        TmpPtr = info->tx_buffer_list[0].virt_addr;
        for (i = 0; i < FrameSize; i++ )
                *TmpPtr++ = i;

        /* setup 1st receive buffer entry: */
        /* clear status, set max receive buffer size */

        info->rx_buffer_list[0].status = 0;
        info->rx_buffer_list[0].count = FrameSize + 4;

        /* zero out the 1st receive buffer */

        memset( info->rx_buffer_list[0].virt_addr, 0, FrameSize + 4 );

        /* Set count field of next buffer entries to prevent */
        /* 16C32 from using buffers after the 1st one. */

        info->tx_buffer_list[1].count = 0;
        info->rx_buffer_list[1].count = 0;
        

        /***************************/
        /* Program 16C32 receiver. */
        /***************************/
        
        spin_lock_irqsave(&info->irq_spinlock,flags);

        /* setup DMA transfers */
        usc_RTCmd( info, RTCmd_PurgeRxFifo );

        /* program 16C32 receiver with physical address of 1st DMA buffer entry */
        phys_addr = info->rx_buffer_list[0].phys_entry;
        usc_OutDmaReg( info, NRARL, (unsigned short)phys_addr );
        usc_OutDmaReg( info, NRARU, (unsigned short)(phys_addr >> 16) );

        /* Clear the Rx DMA status bits (read RDMR) and start channel */
        usc_InDmaReg( info, RDMR );
        usc_DmaCmd( info, DmaCmd_InitRxChannel );

        /* Enable Receiver (RMR <1..0> = 10) */
        usc_OutReg( info, RMR, (unsigned short)((usc_InReg(info, RMR) & 0xfffc) | 0x0002) );
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);


        /*************************************************************/
        /* WAIT FOR RECEIVER TO DMA ALL PARAMETERS FROM BUFFER ENTRY */
        /*************************************************************/

        /* Wait 100ms for interrupt. */
        EndTime = jiffies + msecs_to_jiffies(100);

        for(;;) {
                if (time_after(jiffies, EndTime)) {
                        rc = false;
                        break;
                }

                spin_lock_irqsave(&info->irq_spinlock,flags);
                status = usc_InDmaReg( info, RDMR );
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                if ( !(status & BIT4) && (status & BIT5) ) {
                        /* INITG (BIT 4) is inactive (no entry read in progress) AND */
                        /* BUSY  (BIT 5) is active (channel still active). */
                        /* This means the buffer entry read has completed. */
                        break;
                }
        }


        /******************************/
        /* Program 16C32 transmitter. */
        /******************************/
        
        spin_lock_irqsave(&info->irq_spinlock,flags);

        /* Program the Transmit Character Length Register (TCLR) */
        /* and clear FIFO (TCC is loaded with TCLR on FIFO clear) */

        usc_OutReg( info, TCLR, (unsigned short)info->tx_buffer_list[0].count );
        usc_RTCmd( info, RTCmd_PurgeTxFifo );

        /* Program the address of the 1st DMA Buffer Entry in linked list */

        phys_addr = info->tx_buffer_list[0].phys_entry;
        usc_OutDmaReg( info, NTARL, (unsigned short)phys_addr );
        usc_OutDmaReg( info, NTARU, (unsigned short)(phys_addr >> 16) );

        /* unlatch Tx status bits, and start transmit channel. */

        usc_OutReg( info, TCSR, (unsigned short)(( usc_InReg(info, TCSR) & 0x0f00) | 0xfa) );
        usc_DmaCmd( info, DmaCmd_InitTxChannel );

        /* wait for DMA controller to fill transmit FIFO */

        usc_TCmd( info, TCmd_SelectTicrTxFifostatus );
        
        spin_unlock_irqrestore(&info->irq_spinlock,flags);


        /**********************************/
        /* WAIT FOR TRANSMIT FIFO TO FILL */
        /**********************************/
        
        /* Wait 100ms */
        EndTime = jiffies + msecs_to_jiffies(100);

        for(;;) {
                if (time_after(jiffies, EndTime)) {
                        rc = false;
                        break;
                }

                spin_lock_irqsave(&info->irq_spinlock,flags);
                FifoLevel = usc_InReg(info, TICR) >> 8;
                spin_unlock_irqrestore(&info->irq_spinlock,flags);
                        
                if ( FifoLevel < 16 )
                        break;
                else
                        if ( FrameSize < 32 ) {
                                /* This frame is smaller than the entire transmit FIFO */
                                /* so wait for the entire frame to be loaded. */
                                if ( FifoLevel <= (32 - FrameSize) )
                                        break;
                        }
        }


        if ( rc )
        {
                /* Enable 16C32 transmitter. */

                spin_lock_irqsave(&info->irq_spinlock,flags);
                
                /* Transmit mode Register (TMR), <1..0> = 10, Enable Transmitter */
                usc_TCmd( info, TCmd_SendFrame );
                usc_OutReg( info, TMR, (unsigned short)((usc_InReg(info, TMR) & 0xfffc) | 0x0002) );
                
                spin_unlock_irqrestore(&info->irq_spinlock,flags);


                /******************************/
                /* WAIT FOR TRANSMIT COMPLETE */
                /******************************/

                /* Wait 100ms */
                EndTime = jiffies + msecs_to_jiffies(100);

                /* While timer not expired wait for transmit complete */

                spin_lock_irqsave(&info->irq_spinlock,flags);
                status = usc_InReg( info, TCSR );
                spin_unlock_irqrestore(&info->irq_spinlock,flags);

                while ( !(status & (BIT6 | BIT5 | BIT4 | BIT2 | BIT1)) ) {
                        if (time_after(jiffies, EndTime)) {
                                rc = false;
                                break;
                        }

                        spin_lock_irqsave(&info->irq_spinlock,flags);
                        status = usc_InReg( info, TCSR );
                        spin_unlock_irqrestore(&info->irq_spinlock,flags);
                }
        }


        if ( rc ){
                /* CHECK FOR TRANSMIT ERRORS */
                if ( status & (BIT5 | BIT1) )
                        rc = false;
        }

        if ( rc ) {
                /* WAIT FOR RECEIVE COMPLETE */

                /* Wait 100ms */
                EndTime = jiffies + msecs_to_jiffies(100);

                /* Wait for 16C32 to write receive status to buffer entry. */
                status=info->rx_buffer_list[0].status;
                while ( status == 0 ) {
                        if (time_after(jiffies, EndTime)) {
                                rc = false;
                                break;
                        }
                        status=info->rx_buffer_list[0].status;
                }
        }


        if ( rc ) {
                /* CHECK FOR RECEIVE ERRORS */
                status = info->rx_buffer_list[0].status;

                if ( status & (BIT8 | BIT3 | BIT1) ) {
                        /* receive error has occurred */
                        rc = false;
                } else {
                        if ( memcmp( info->tx_buffer_list[0].virt_addr ,
                                info->rx_buffer_list[0].virt_addr, FrameSize ) ){
                                rc = false;
                        }
                }
        }

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_reset( info );
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        /* restore current port options */
        memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
        
        return rc;

}       /* end of mgsl_dma_test() */

/* mgsl_adapter_test()
 * 
 *      Perform the register, IRQ, and DMA tests for the 16C32.
 *      
 * Arguments:           info    pointer to device instance data
 * Return Value:        0 if success, otherwise -ENODEV
 */
static int mgsl_adapter_test( struct mgsl_struct *info )
{
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):Testing device %s\n",
                        __FILE__,__LINE__,info->device_name );
                        
        if ( !mgsl_register_test( info ) ) {
                info->init_error = DiagStatus_AddressFailure;
                printk( "%s(%d):Register test failure for device %s Addr=%04X\n",
                        __FILE__,__LINE__,info->device_name, (unsigned short)(info->io_base) );
                return -ENODEV;
        }

        if ( !mgsl_irq_test( info ) ) {
                info->init_error = DiagStatus_IrqFailure;
                printk( "%s(%d):Interrupt test failure for device %s IRQ=%d\n",
                        __FILE__,__LINE__,info->device_name, (unsigned short)(info->irq_level) );
                return -ENODEV;
        }

        if ( !mgsl_dma_test( info ) ) {
                info->init_error = DiagStatus_DmaFailure;
                printk( "%s(%d):DMA test failure for device %s DMA=%d\n",
                        __FILE__,__LINE__,info->device_name, (unsigned short)(info->dma_level) );
                return -ENODEV;
        }

        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):device %s passed diagnostics\n",
                        __FILE__,__LINE__,info->device_name );
                        
        return 0;

}       /* end of mgsl_adapter_test() */

/* mgsl_memory_test()
 * 
 *      Test the shared memory on a PCI adapter.
 * 
 * Arguments:           info    pointer to device instance data
 * Return Value:        true if test passed, otherwise false
 */
static bool mgsl_memory_test( struct mgsl_struct *info )
{
        static unsigned long BitPatterns[] =
                { 0x0, 0x55555555, 0xaaaaaaaa, 0x66666666, 0x99999999, 0xffffffff, 0x12345678 };
        unsigned long Patterncount = ARRAY_SIZE(BitPatterns);
        unsigned long i;
        unsigned long TestLimit = SHARED_MEM_ADDRESS_SIZE/sizeof(unsigned long);
        unsigned long * TestAddr;

        if ( info->bus_type != MGSL_BUS_TYPE_PCI )
                return true;

        TestAddr = (unsigned long *)info->memory_base;

        /* Test data lines with test pattern at one location. */

        for ( i = 0 ; i < Patterncount ; i++ ) {
                *TestAddr = BitPatterns[i];
                if ( *TestAddr != BitPatterns[i] )
                        return false;
        }

        /* Test address lines with incrementing pattern over */
        /* entire address range. */

        for ( i = 0 ; i < TestLimit ; i++ ) {
                *TestAddr = i * 4;
                TestAddr++;
        }

        TestAddr = (unsigned long *)info->memory_base;

        for ( i = 0 ; i < TestLimit ; i++ ) {
                if ( *TestAddr != i * 4 )
                        return false;
                TestAddr++;
        }

        memset( info->memory_base, 0, SHARED_MEM_ADDRESS_SIZE );

        return true;

}       /* End Of mgsl_memory_test() */


/* mgsl_load_pci_memory()
 * 
 *      Load a large block of data into the PCI shared memory.
 *      Use this instead of memcpy() or memmove() to move data
 *      into the PCI shared memory.
 * 
 * Notes:
 * 
 *      This function prevents the PCI9050 interface chip from hogging
 *      the adapter local bus, which can starve the 16C32 by preventing
 *      16C32 bus master cycles.
 * 
 *      The PCI9050 documentation says that the 9050 will always release
 *      control of the local bus after completing the current read
 *      or write operation.
 * 
 *      It appears that as long as the PCI9050 write FIFO is full, the
 *      PCI9050 treats all of the writes as a single burst transaction
 *      and will not release the bus. This causes DMA latency problems
 *      at high speeds when copying large data blocks to the shared
 *      memory.
 * 
 *      This function in effect, breaks the a large shared memory write
 *      into multiple transations by interleaving a shared memory read
 *      which will flush the write FIFO and 'complete' the write
 *      transation. This allows any pending DMA request to gain control
 *      of the local bus in a timely fasion.
 * 
 * Arguments:
 * 
 *      TargetPtr       pointer to target address in PCI shared memory
 *      SourcePtr       pointer to source buffer for data
 *      count           count in bytes of data to copy
 *
 * Return Value:        None
 */
static void mgsl_load_pci_memory( char* TargetPtr, const char* SourcePtr,
        unsigned short count )
{
        /* 16 32-bit writes @ 60ns each = 960ns max latency on local bus */
#define PCI_LOAD_INTERVAL 64

        unsigned short Intervalcount = count / PCI_LOAD_INTERVAL;
        unsigned short Index;
        unsigned long Dummy;

        for ( Index = 0 ; Index < Intervalcount ; Index++ )
        {
                memcpy(TargetPtr, SourcePtr, PCI_LOAD_INTERVAL);
                Dummy = *((volatile unsigned long *)TargetPtr);
                TargetPtr += PCI_LOAD_INTERVAL;
                SourcePtr += PCI_LOAD_INTERVAL;
        }

        memcpy( TargetPtr, SourcePtr, count % PCI_LOAD_INTERVAL );

}       /* End Of mgsl_load_pci_memory() */

static void mgsl_trace_block(struct mgsl_struct *info,const char* data, int count, int xmit)
{
        int i;
        int linecount;
        if (xmit)
                printk("%s tx data:\n",info->device_name);
        else
                printk("%s rx data:\n",info->device_name);
                
        while(count) {
                if (count > 16)
                        linecount = 16;
                else
                        linecount = count;
                        
                for(i=0;i<linecount;i++)
                        printk("%02X ",(unsigned char)data[i]);
                for(;i<17;i++)
                        printk("   ");
                for(i=0;i<linecount;i++) {
                        if (data[i]>=040 && data[i]<=0176)
                                printk("%c",data[i]);
                        else
                                printk(".");
                }
                printk("\n");
                
                data  += linecount;
                count -= linecount;
        }
}       /* end of mgsl_trace_block() */

/* mgsl_tx_timeout()
 * 
 *      called when HDLC frame times out
 *      update stats and do tx completion processing
 *      
 * Arguments:   context         pointer to device instance data
 * Return Value:        None
 */
static void mgsl_tx_timeout(struct timer_list *t)
{
        struct mgsl_struct *info = from_timer(info, t, tx_timer);
        unsigned long flags;
        
        if ( debug_level >= DEBUG_LEVEL_INFO )
                printk( "%s(%d):mgsl_tx_timeout(%s)\n",
                        __FILE__,__LINE__,info->device_name);
        if(info->tx_active &&
           (info->params.mode == MGSL_MODE_HDLC ||
            info->params.mode == MGSL_MODE_RAW) ) {
                info->icount.txtimeout++;
        }
        spin_lock_irqsave(&info->irq_spinlock,flags);
        info->tx_active = false;
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

        if ( info->params.flags & HDLC_FLAG_HDLC_LOOPMODE )
                usc_loopmode_cancel_transmit( info );

        spin_unlock_irqrestore(&info->irq_spinlock,flags);
        
#if SYNCLINK_GENERIC_HDLC
        if (info->netcount)
                hdlcdev_tx_done(info);
        else
#endif
                mgsl_bh_transmit(info);
        
}       /* end of mgsl_tx_timeout() */

/* signal that there are no more frames to send, so that
 * line is 'released' by echoing RxD to TxD when current
 * transmission is complete (or immediately if no tx in progress).
 */
static int mgsl_loopmode_send_done( struct mgsl_struct * info )
{
        unsigned long flags;
        
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (info->params.flags & HDLC_FLAG_HDLC_LOOPMODE) {
                if (info->tx_active)
                        info->loopmode_send_done_requested = true;
                else
                        usc_loopmode_send_done(info);
        }
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        return 0;
}

/* release the line by echoing RxD to TxD
 * upon completion of a transmit frame
 */
static void usc_loopmode_send_done( struct mgsl_struct * info )
{
        info->loopmode_send_done_requested = false;
        /* clear CMR:13 to 0 to start echoing RxData to TxData */
        info->cmr_value &= ~BIT13;
        usc_OutReg(info, CMR, info->cmr_value);
}

/* abort a transmit in progress while in HDLC LoopMode
 */
static void usc_loopmode_cancel_transmit( struct mgsl_struct * info )
{
        /* reset tx dma channel and purge TxFifo */
        usc_RTCmd( info, RTCmd_PurgeTxFifo );
        usc_DmaCmd( info, DmaCmd_ResetTxChannel );
        usc_loopmode_send_done( info );
}

/* for HDLC/SDLC LoopMode, setting CMR:13 after the transmitter is enabled
 * is an Insert Into Loop action. Upon receipt of a GoAhead sequence (RxAbort)
 * we must clear CMR:13 to begin repeating TxData to RxData
 */
static void usc_loopmode_insert_request( struct mgsl_struct * info )
{
        info->loopmode_insert_requested = true;
 
        /* enable RxAbort irq. On next RxAbort, clear CMR:13 to
         * begin repeating TxData on RxData (complete insertion)
         */
        usc_OutReg( info, RICR, 
                (usc_InReg( info, RICR ) | RXSTATUS_ABORT_RECEIVED ) );
                
        /* set CMR:13 to insert into loop on next GoAhead (RxAbort) */
        info->cmr_value |= BIT13;
        usc_OutReg(info, CMR, info->cmr_value);
}

/* return 1 if station is inserted into the loop, otherwise 0
 */
static int usc_loopmode_active( struct mgsl_struct * info)
{
        return usc_InReg( info, CCSR ) & BIT7 ? 1 : 0 ;
}

#if SYNCLINK_GENERIC_HDLC

/**
 * called by generic HDLC layer when protocol selected (PPP, frame relay, etc.)
 * set encoding and frame check sequence (FCS) options
 *
 * dev       pointer to network device structure
 * encoding  serial encoding setting
 * parity    FCS setting
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_attach(struct net_device *dev, unsigned short encoding,
                          unsigned short parity)
{
        struct mgsl_struct *info = dev_to_port(dev);
        unsigned char  new_encoding;
        unsigned short new_crctype;

        /* return error if TTY interface open */
        if (info->port.count)
                return -EBUSY;

        switch (encoding)
        {
        case ENCODING_NRZ:        new_encoding = HDLC_ENCODING_NRZ; break;
        case ENCODING_NRZI:       new_encoding = HDLC_ENCODING_NRZI_SPACE; break;
        case ENCODING_FM_MARK:    new_encoding = HDLC_ENCODING_BIPHASE_MARK; break;
        case ENCODING_FM_SPACE:   new_encoding = HDLC_ENCODING_BIPHASE_SPACE; break;
        case ENCODING_MANCHESTER: new_encoding = HDLC_ENCODING_BIPHASE_LEVEL; break;
        default: return -EINVAL;
        }

        switch (parity)
        {
        case PARITY_NONE:            new_crctype = HDLC_CRC_NONE; break;
        case PARITY_CRC16_PR1_CCITT: new_crctype = HDLC_CRC_16_CCITT; break;
        case PARITY_CRC32_PR1_CCITT: new_crctype = HDLC_CRC_32_CCITT; break;
        default: return -EINVAL;
        }

        info->params.encoding = new_encoding;
        info->params.crc_type = new_crctype;

        /* if network interface up, reprogram hardware */
        if (info->netcount)
                mgsl_program_hw(info);

        return 0;
}

/**
 * called by generic HDLC layer to send frame
 *
 * skb  socket buffer containing HDLC frame
 * dev  pointer to network device structure
 */
static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
                                      struct net_device *dev)
{
        struct mgsl_struct *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk(KERN_INFO "%s:hdlc_xmit(%s)\n",__FILE__,dev->name);

        /* stop sending until this frame completes */
        netif_stop_queue(dev);

        /* copy data to device buffers */
        info->xmit_cnt = skb->len;
        mgsl_load_tx_dma_buffer(info, skb->data, skb->len);

        /* update network statistics */
        dev->stats.tx_packets++;
        dev->stats.tx_bytes += skb->len;

        /* done with socket buffer, so free it */
        dev_kfree_skb(skb);

        /* save start time for transmit timeout detection */
        netif_trans_update(dev);

        /* start hardware transmitter if necessary */
        spin_lock_irqsave(&info->irq_spinlock,flags);
        if (!info->tx_active)
                usc_start_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        return NETDEV_TX_OK;
}

/**
 * called by network layer when interface enabled
 * claim resources and initialize hardware
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_open(struct net_device *dev)
{
        struct mgsl_struct *info = dev_to_port(dev);
        int rc;
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_open(%s)\n",__FILE__,dev->name);

        /* generic HDLC layer open processing */
        rc = hdlc_open(dev);
        if (rc)
                return rc;

        /* arbitrate between network and tty opens */
        spin_lock_irqsave(&info->netlock, flags);
        if (info->port.count != 0 || info->netcount != 0) {
                printk(KERN_WARNING "%s: hdlc_open returning busy\n", dev->name);
                spin_unlock_irqrestore(&info->netlock, flags);
                return -EBUSY;
        }
        info->netcount=1;
        spin_unlock_irqrestore(&info->netlock, flags);

        /* claim resources and init adapter */
        if ((rc = startup(info)) != 0) {
                spin_lock_irqsave(&info->netlock, flags);
                info->netcount=0;
                spin_unlock_irqrestore(&info->netlock, flags);
                return rc;
        }

        /* assert RTS and DTR, apply hardware settings */
        info->serial_signals |= SerialSignal_RTS | SerialSignal_DTR;
        mgsl_program_hw(info);

        /* enable network layer transmit */
        netif_trans_update(dev);
        netif_start_queue(dev);

        /* inform generic HDLC layer of current DCD status */
        spin_lock_irqsave(&info->irq_spinlock, flags);
        usc_get_serial_signals(info);
        spin_unlock_irqrestore(&info->irq_spinlock, flags);
        if (info->serial_signals & SerialSignal_DCD)
                netif_carrier_on(dev);
        else
                netif_carrier_off(dev);
        return 0;
}

/**
 * called by network layer when interface is disabled
 * shutdown hardware and release resources
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_close(struct net_device *dev)
{
        struct mgsl_struct *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_close(%s)\n",__FILE__,dev->name);

        netif_stop_queue(dev);

        /* shutdown adapter and release resources */
        shutdown(info);

        hdlc_close(dev);

        spin_lock_irqsave(&info->netlock, flags);
        info->netcount=0;
        spin_unlock_irqrestore(&info->netlock, flags);

        return 0;
}

/**
 * called by network layer to process IOCTL call to network device
 *
 * dev  pointer to network device structure
 * ifr  pointer to network interface request structure
 * cmd  IOCTL command code
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        const size_t size = sizeof(sync_serial_settings);
        sync_serial_settings new_line;
        sync_serial_settings __user *line = ifr->ifr_settings.ifs_ifsu.sync;
        struct mgsl_struct *info = dev_to_port(dev);
        unsigned int flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("%s:hdlcdev_ioctl(%s)\n",__FILE__,dev->name);

        /* return error if TTY interface open */
        if (info->port.count)
                return -EBUSY;

        if (cmd != SIOCWANDEV)
                return hdlc_ioctl(dev, ifr, cmd);

        switch(ifr->ifr_settings.type) {
        case IF_GET_IFACE: /* return current sync_serial_settings */

                ifr->ifr_settings.type = IF_IFACE_SYNC_SERIAL;
                if (ifr->ifr_settings.size < size) {
                        ifr->ifr_settings.size = size; /* data size wanted */
                        return -ENOBUFS;
                }

                flags = info->params.flags & (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                              HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                              HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                              HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);

                memset(&new_line, 0, sizeof(new_line));
                switch (flags){
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
                case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_TXINT; break;
                case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN): new_line.clock_type = CLOCK_TXFROMRX; break;
                default: new_line.clock_type = CLOCK_DEFAULT;
                }

                new_line.clock_rate = info->params.clock_speed;
                new_line.loopback   = info->params.loopback ? 1:0;

                if (copy_to_user(line, &new_line, size))
                        return -EFAULT;
                return 0;

        case IF_IFACE_SYNC_SERIAL: /* set sync_serial_settings */

                if(!capable(CAP_NET_ADMIN))
                        return -EPERM;
                if (copy_from_user(&new_line, line, size))
                        return -EFAULT;

                switch (new_line.clock_type)
                {
                case CLOCK_EXT:      flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN; break;
                case CLOCK_TXFROMRX: flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN; break;
                case CLOCK_INT:      flags = HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG;    break;
                case CLOCK_TXINT:    flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG;    break;
                case CLOCK_DEFAULT:  flags = info->params.flags &
                                             (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                              HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                              HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                              HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN); break;
                default: return -EINVAL;
                }

                if (new_line.loopback != 0 && new_line.loopback != 1)
                        return -EINVAL;

                info->params.flags &= ~(HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
                                        HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
                                        HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
                                        HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
                info->params.flags |= flags;

                info->params.loopback = new_line.loopback;

                if (flags & (HDLC_FLAG_RXC_BRG | HDLC_FLAG_TXC_BRG))
                        info->params.clock_speed = new_line.clock_rate;
                else
                        info->params.clock_speed = 0;

                /* if network interface up, reprogram hardware */
                if (info->netcount)
                        mgsl_program_hw(info);
                return 0;

        default:
                return hdlc_ioctl(dev, ifr, cmd);
        }
}

/**
 * called by network layer when transmit timeout is detected
 *
 * dev  pointer to network device structure
 */
static void hdlcdev_tx_timeout(struct net_device *dev)
{
        struct mgsl_struct *info = dev_to_port(dev);
        unsigned long flags;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("hdlcdev_tx_timeout(%s)\n",dev->name);

        dev->stats.tx_errors++;
        dev->stats.tx_aborted_errors++;

        spin_lock_irqsave(&info->irq_spinlock,flags);
        usc_stop_transmitter(info);
        spin_unlock_irqrestore(&info->irq_spinlock,flags);

        netif_wake_queue(dev);
}

/**
 * called by device driver when transmit completes
 * reenable network layer transmit if stopped
 *
 * info  pointer to device instance information
 */
static void hdlcdev_tx_done(struct mgsl_struct *info)
{
        if (netif_queue_stopped(info->netdev))
                netif_wake_queue(info->netdev);
}

/**
 * called by device driver when frame received
 * pass frame to network layer
 *
 * info  pointer to device instance information
 * buf   pointer to buffer contianing frame data
 * size  count of data bytes in buf
 */
static void hdlcdev_rx(struct mgsl_struct *info, char *buf, int size)
{
        struct sk_buff *skb = dev_alloc_skb(size);
        struct net_device *dev = info->netdev;

        if (debug_level >= DEBUG_LEVEL_INFO)
                printk("hdlcdev_rx(%s)\n", dev->name);

        if (skb == NULL) {
                printk(KERN_NOTICE "%s: can't alloc skb, dropping packet\n",
                       dev->name);
                dev->stats.rx_dropped++;
                return;
        }

        skb_put_data(skb, buf, size);

        skb->protocol = hdlc_type_trans(skb, dev);

        dev->stats.rx_packets++;
        dev->stats.rx_bytes += size;

        netif_rx(skb);
}

static const struct net_device_ops hdlcdev_ops = {
        .ndo_open       = hdlcdev_open,
        .ndo_stop       = hdlcdev_close,
        .ndo_start_xmit = hdlc_start_xmit,
        .ndo_do_ioctl   = hdlcdev_ioctl,
        .ndo_tx_timeout = hdlcdev_tx_timeout,
};

/**
 * called by device driver when adding device instance
 * do generic HDLC initialization
 *
 * info  pointer to device instance information
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_init(struct mgsl_struct *info)
{
        int rc;
        struct net_device *dev;
        hdlc_device *hdlc;

        /* allocate and initialize network and HDLC layer objects */

        dev = alloc_hdlcdev(info);
        if (!dev) {
                printk(KERN_ERR "%s:hdlc device allocation failure\n",__FILE__);
                return -ENOMEM;
        }

        /* for network layer reporting purposes only */
        dev->base_addr = info->io_base;
        dev->irq       = info->irq_level;
        dev->dma       = info->dma_level;

        /* network layer callbacks and settings */
        dev->netdev_ops     = &hdlcdev_ops;
        dev->watchdog_timeo = 10 * HZ;
        dev->tx_queue_len   = 50;

        /* generic HDLC layer callbacks and settings */
        hdlc         = dev_to_hdlc(dev);
        hdlc->attach = hdlcdev_attach;
        hdlc->xmit   = hdlcdev_xmit;

        /* register objects with HDLC layer */
        rc = register_hdlc_device(dev);
        if (rc) {
                printk(KERN_WARNING "%s:unable to register hdlc device\n",__FILE__);
                free_netdev(dev);
                return rc;
        }

        info->netdev = dev;
        return 0;
}

/**
 * called by device driver when removing device instance
 * do generic HDLC cleanup
 *
 * info  pointer to device instance information
 */
static void hdlcdev_exit(struct mgsl_struct *info)
{
        unregister_hdlc_device(info->netdev);
        free_netdev(info->netdev);
        info->netdev = NULL;
}

#endif /* CONFIG_HDLC */


static int synclink_init_one (struct pci_dev *dev,
                                        const struct pci_device_id *ent)
{
        struct mgsl_struct *info;

        if (pci_enable_device(dev)) {
                printk("error enabling pci device %p\n", dev);
                return -EIO;
        }

        info = mgsl_allocate_device();
        if (!info) {
                printk("can't allocate device instance data.\n");
                return -EIO;
        }

        /* Copy user configuration info to device instance data */
                
        info->io_base = pci_resource_start(dev, 2);
        info->irq_level = dev->irq;
        info->phys_memory_base = pci_resource_start(dev, 3);
                                
        /* Because veremap only works on page boundaries we must map
         * a larger area than is actually implemented for the LCR
         * memory range. We map a full page starting at the page boundary.
         */
        info->phys_lcr_base = pci_resource_start(dev, 0);
        info->lcr_offset    = info->phys_lcr_base & (PAGE_SIZE-1);
        info->phys_lcr_base &= ~(PAGE_SIZE-1);
                                
        info->bus_type = MGSL_BUS_TYPE_PCI;
        info->io_addr_size = 8;
        info->irq_flags = IRQF_SHARED;

        if (dev->device == 0x0210) {
                /* Version 1 PCI9030 based universal PCI adapter */
                info->misc_ctrl_value = 0x007c4080;
                info->hw_version = 1;
        } else {
                /* Version 0 PCI9050 based 5V PCI adapter
                 * A PCI9050 bug prevents reading LCR registers if 
                 * LCR base address bit 7 is set. Maintain shadow
                 * value so we can write to LCR misc control reg.
                 */
                info->misc_ctrl_value = 0x087e4546;
                info->hw_version = 0;
        }
                                
        mgsl_add_device(info);

        return 0;
}

static void synclink_remove_one (struct pci_dev *dev)
{
}