Indentation fix, cleanup.

[AROS.git] / arch / all-pc / boot / grub / netboot / depca.c

/* Etherboot: depca.h merged, comments from Linux driver retained */
/*  depca.c: A DIGITAL DEPCA  & EtherWORKS ethernet driver for linux.

    Written 1994, 1995 by David C. Davies.


                      Copyright 1994 David C. Davies
                                   and 
                         United States Government
         (as represented by the Director, National Security Agency).  

               Copyright 1995  Digital Equipment Corporation.


    This software may be used and distributed according to the terms of
    the GNU Public License, incorporated herein by reference.

    This driver is written for the Digital Equipment Corporation series
    of DEPCA and EtherWORKS ethernet cards:

        DEPCA       (the original)
        DE100
        DE101
        DE200 Turbo
        DE201 Turbo
        DE202 Turbo (TP BNC)
        DE210
        DE422       (EISA)

    The  driver has been tested on DE100, DE200 and DE202 cards  in  a
    relatively busy network. The DE422 has been tested a little.

    This  driver will NOT work   for the DE203,  DE204  and DE205 series  of
    cards,  since they have  a  new custom ASIC in   place of the AMD  LANCE
    chip.  See the 'ewrk3.c'   driver in the  Linux  source tree for running
    those cards.

    I have benchmarked the driver with a  DE100 at 595kB/s to (542kB/s from)
    a DECstation 5000/200.

    The author may be reached at davies@maniac.ultranet.com

    =========================================================================

    The  driver was originally based  on   the 'lance.c' driver from  Donald
    Becker   which  is included with  the  standard  driver distribution for
    linux.  V0.4  is  a complete  re-write  with only  the kernel  interface
    remaining from the original code.

    1) Lance.c code in /linux/drivers/net/
    2) "Ethernet/IEEE 802.3 Family. 1992 World Network Data Book/Handbook",
       AMD, 1992 [(800) 222-9323].
    3) "Am79C90 CMOS Local Area Network Controller for Ethernet (C-LANCE)",
       AMD, Pub. #17881, May 1993.
    4) "Am79C960 PCnet-ISA(tm), Single-Chip Ethernet Controller for ISA",
       AMD, Pub. #16907, May 1992
    5) "DEC EtherWORKS LC Ethernet Controller Owners Manual",
       Digital Equipment corporation, 1990, Pub. #EK-DE100-OM.003
    6) "DEC EtherWORKS Turbo Ethernet Controller Owners Manual",
       Digital Equipment corporation, 1990, Pub. #EK-DE200-OM.003
    7) "DEPCA Hardware Reference Manual", Pub. #EK-DEPCA-PR
       Digital Equipment Corporation, 1989
    8) "DEC EtherWORKS Turbo_(TP BNC) Ethernet Controller Owners Manual",
       Digital Equipment corporation, 1991, Pub. #EK-DE202-OM.001
    

    Peter Bauer's depca.c (V0.5) was referred to when debugging V0.1 of this
    driver.

    The original DEPCA  card requires that the  ethernet ROM address counter
    be enabled to count and has an 8 bit NICSR.  The ROM counter enabling is
    only  done when a  0x08 is read as the  first address octet (to minimise
    the chances  of writing over some  other hardware's  I/O register).  The
    NICSR accesses   have been changed  to  byte accesses  for all the cards
    supported by this driver, since there is only one  useful bit in the MSB
    (remote boot timeout) and it  is not used.  Also, there  is a maximum of
    only 48kB network  RAM for this  card.  My thanks  to Torbjorn Lindh for
    help debugging all this (and holding my feet to  the fire until I got it
    right).

    The DE200  series  boards have  on-board 64kB  RAM for  use  as a shared
    memory network  buffer. Only the DE100  cards make use  of a  2kB buffer
    mode which has not  been implemented in  this driver (only the 32kB  and
    64kB modes are supported [16kB/48kB for the original DEPCA]).

    At the most only 2 DEPCA cards can  be supported on  the ISA bus because
    there is only provision  for two I/O base addresses  on each card (0x300
    and 0x200). The I/O address is detected by searching for a byte sequence
    in the Ethernet station address PROM at the expected I/O address for the
    Ethernet  PROM.   The shared memory  base   address  is 'autoprobed'  by
    looking  for the self  test PROM  and detecting the  card name.   When a
    second  DEPCA is  detected,  information  is   placed in the   base_addr
    variable of the  next device structure (which  is created if necessary),
    thus  enabling ethif_probe  initialization  for the device.  More than 2
    EISA cards can  be  supported, but  care will  be  needed assigning  the
    shared memory to ensure that each slot has the  correct IRQ, I/O address
    and shared memory address assigned.

    ************************************************************************

    NOTE: If you are using two  ISA DEPCAs, it is  important that you assign
    the base memory addresses correctly.   The  driver autoprobes I/O  0x300
    then 0x200.  The  base memory address for  the first device must be less
    than that of the second so that the auto probe will correctly assign the
    I/O and memory addresses on the same card.  I can't think of a way to do
    this unambiguously at the moment, since there is nothing on the cards to
    tie I/O and memory information together.

    I am unable  to  test  2 cards   together for now,    so this  code   is
    unchecked. All reports, good or bad, are welcome.

    ************************************************************************

    The board IRQ   setting must be  at an  unused IRQ which  is auto-probed
    using Donald Becker's autoprobe routines. DEPCA and DE100 board IRQs are
    {2,3,4,5,7}, whereas the  DE200 is at {5,9,10,11,15}.  Note that IRQ2 is
    really IRQ9 in machines with 16 IRQ lines.

    No 16MB memory  limitation should exist with this  driver as DMA is  not
    used and the common memory area is in low memory on the network card (my
    current system has 20MB and I've not had problems yet).

    The ability to load this driver as a loadable module has been added. To
    utilise this ability, you have to do <8 things:

    0) have a copy of the loadable modules code installed on your system.
    1) copy depca.c from the  /linux/drivers/net directory to your favourite
    temporary directory.
    2) if you wish, edit the  source code near  line 1530 to reflect the I/O
    address and IRQ you're using (see also 5).
    3) compile  depca.c, but include -DMODULE in  the command line to ensure
    that the correct bits are compiled (see end of source code).
    4) if you are wanting to add a new  card, goto 5. Otherwise, recompile a
    kernel with the depca configuration turned off and reboot.
    5) insmod depca.o [irq=7] [io=0x200] [mem=0xd0000] [adapter_name=DE100]
       [Alan Cox: Changed the code to allow command line irq/io assignments]
       [Dave Davies: Changed the code to allow command line mem/name
                                                                assignments]
    6) run the net startup bits for your eth?? interface manually 
    (usually /etc/rc.inet[12] at boot time). 
    7) enjoy!

    Note that autoprobing is not allowed in loadable modules - the system is
    already up and running and you're messing with interrupts.

    To unload a module, turn off the associated interface 
    'ifconfig eth?? down' then 'rmmod depca'.

    To assign a base memory address for the shared memory  when running as a
    loadable module, see 5 above.  To include the adapter  name (if you have
    no PROM  but know the card name)  also see 5  above. Note that this last
    option  will not work  with kernel  built-in  depca's. 

    The shared memory assignment for a loadable module  makes sense to avoid
    the 'memory autoprobe' picking the wrong shared memory  (for the case of
    2 depca's in a PC).

    ************************************************************************
    Support for MCA EtherWORKS cards added 11-3-98.
    Verified to work with up to 2 DE212 cards in a system (although not
      fully stress-tested).  

    Currently known bugs/limitations:

    Note:  with the MCA stuff as a module, it trusts the MCA configuration,
           not the command line for IRQ and memory address.  You can
           specify them if you want, but it will throw your values out.
           You still have to pass the IO address it was configured as
           though.

    ************************************************************************
    TO DO:
    ------


    Revision History
    ----------------

    Version   Date        Description
  
      0.1     25-jan-94   Initial writing.
      0.2     27-jan-94   Added LANCE TX hardware buffer chaining.
      0.3      1-feb-94   Added multiple DEPCA support.
      0.31     4-feb-94   Added DE202 recognition.
      0.32    19-feb-94   Tidy up. Improve multi-DEPCA support.
      0.33    25-feb-94   Fix DEPCA ethernet ROM counter enable.
                          Add jabber packet fix from murf@perftech.com
                          and becker@super.org
      0.34     7-mar-94   Fix DEPCA max network memory RAM & NICSR access.
      0.35     8-mar-94   Added DE201 recognition. Tidied up.
      0.351   30-apr-94   Added EISA support. Added DE422 recognition.
      0.36    16-may-94   DE422 fix released.
      0.37    22-jul-94   Added MODULE support
      0.38    15-aug-94   Added DBR ROM switch in depca_close(). 
                          Multi DEPCA bug fix.
      0.38axp 15-sep-94   Special version for Alpha AXP Linux V1.0.
      0.381   12-dec-94   Added DE101 recognition, fix multicast bug.
      0.382    9-feb-95   Fix recognition bug reported by <bkm@star.rl.ac.uk>.
      0.383   22-feb-95   Fix for conflict with VESA SCSI reported by
                          <stromain@alf.dec.com>
      0.384   17-mar-95   Fix a ring full bug reported by <bkm@star.rl.ac.uk>
      0.385    3-apr-95   Fix a recognition bug reported by 
                                                <ryan.niemi@lastfrontier.com>
      0.386   21-apr-95   Fix the last fix...sorry, must be galloping senility
      0.40    25-May-95   Rewrite for portability & updated.
                          ALPHA support from <jestabro@amt.tay1.dec.com>
      0.41    26-Jun-95   Added verify_area() calls in depca_ioctl() from
                          suggestion by <heiko@colossus.escape.de>
      0.42    27-Dec-95   Add 'mem' shared memory assignment for loadable 
                          modules.
                          Add 'adapter_name' for loadable modules when no PROM.
                          Both above from a suggestion by 
                          <pchen@woodruffs121.residence.gatech.edu>.
                          Add new multicasting code.
      0.421   22-Apr-96   Fix alloc_device() bug <jari@markkus2.fimr.fi>
      0.422   29-Apr-96   Fix depca_hw_init() bug <jari@markkus2.fimr.fi>
      0.423    7-Jun-96   Fix module load bug <kmg@barco.be>
      0.43    16-Aug-96   Update alloc_device() to conform to de4x5.c
      0.44     1-Sep-97   Fix *_probe() to test check_region() first - bug
                           reported by <mmogilvi@elbert.uccs.edu>
      0.45     3-Nov-98   Added support for MCA EtherWORKS (DE210/DE212) cards
                           by <tymm@computer.org> 
      0.451    5-Nov-98   Fixed mca stuff cuz I'm a dummy. <tymm@computer.org>
      0.5     14-Nov-98   Re-spin for 2.1.x kernels.
      0.51    27-Jun-99   Correct received packet length for CRC from
                           report by <worm@dkik.dk>

    =========================================================================
*/

#include "etherboot.h"
#include "nic.h"
#include "cards.h"

/*
** I/O addresses. Note that the 2k buffer option is not supported in
** this driver.
*/
#define DEPCA_NICSR ioaddr+0x00   /* Network interface CSR */
#define DEPCA_RBI   ioaddr+0x02   /* RAM buffer index (2k buffer mode) */
#define DEPCA_DATA  ioaddr+0x04   /* LANCE registers' data port */
#define DEPCA_ADDR  ioaddr+0x06   /* LANCE registers' address port */
#define DEPCA_HBASE ioaddr+0x08   /* EISA high memory base address reg. */
#define DEPCA_PROM  ioaddr+0x0c   /* Ethernet address ROM data port */
#define DEPCA_CNFG  ioaddr+0x0c   /* EISA Configuration port */
#define DEPCA_RBSA  ioaddr+0x0e   /* RAM buffer starting address (2k buff.) */

/*
** These are LANCE registers addressable through DEPCA_ADDR 
*/
#define CSR0       0
#define CSR1       1
#define CSR2       2
#define CSR3       3

/* 
** NETWORK INTERFACE CSR (NI_CSR) bit definitions 
*/
 
#define TO              0x0100  /* Time Out for remote boot */
#define SHE             0x0080  /* SHadow memory Enable */
#define BS              0x0040  /* Bank Select */
#define BUF             0x0020  /* BUFfer size (1->32k, 0->64k) */
#define RBE             0x0010  /* Remote Boot Enable (1->net boot) */
#define AAC             0x0008  /* Address ROM Address Counter (1->enable) */
#define _128KB          0x0008  /* 128kB Network RAM (1->enable) */
#define IM              0x0004  /* Interrupt Mask (1->mask) */
#define IEN             0x0002  /* Interrupt tristate ENable (1->enable) */
#define LED             0x0001  /* LED control */

/* 
** Control and Status Register 0 (CSR0) bit definitions 
*/

#define ERR             0x8000  /* Error summary */
#define BABL            0x4000  /* Babble transmitter timeout error  */
#define CERR            0x2000  /* Collision Error */
#define MISS            0x1000  /* Missed packet */
#define MERR            0x0800  /* Memory Error */
#define RINT            0x0400  /* Receiver Interrupt */
#define TINT            0x0200  /* Transmit Interrupt */
#define IDON            0x0100  /* Initialization Done */
#define INTR            0x0080  /* Interrupt Flag */
#define INEA            0x0040  /* Interrupt Enable */
#define RXON            0x0020  /* Receiver on */
#define TXON            0x0010  /* Transmitter on */
#define TDMD            0x0008  /* Transmit Demand */
#define STOP            0x0004  /* Stop */
#define STRT            0x0002  /* Start */
#define INIT            0x0001  /* Initialize */
#define INTM            0xff00  /* Interrupt Mask */
#define INTE            0xfff0  /* Interrupt Enable */

/*
** CONTROL AND STATUS REGISTER 3 (CSR3)
*/

#define BSWP            0x0004  /* Byte SWaP */
#define ACON            0x0002  /* ALE control */
#define BCON            0x0001  /* Byte CONtrol */

/*
** Initialization Block Mode Register 
*/

#define PROM            0x8000  /* Promiscuous Mode */
#define EMBA            0x0080  /* Enable Modified Back-off Algorithm */
#define INTL            0x0040  /* Internal Loopback */
#define DRTY            0x0020  /* Disable Retry */
#define COLL            0x0010  /* Force Collision */
#define DTCR            0x0008  /* Disable Transmit CRC */
#define LOOP            0x0004  /* Loopback */
#define DTX             0x0002  /* Disable the Transmitter */
#define DRX             0x0001  /* Disable the Receiver */

/*
** Receive Message Descriptor 1 (RMD1) bit definitions. 
*/

#define R_OWN       0x80000000  /* Owner bit 0 = host, 1 = lance */
#define R_ERR           0x4000  /* Error Summary */
#define R_FRAM          0x2000  /* Framing Error */
#define R_OFLO          0x1000  /* Overflow Error */
#define R_CRC           0x0800  /* CRC Error */
#define R_BUFF          0x0400  /* Buffer Error */
#define R_STP           0x0200  /* Start of Packet */
#define R_ENP           0x0100  /* End of Packet */

/*
** Transmit Message Descriptor 1 (TMD1) bit definitions. 
*/

#define T_OWN       0x80000000  /* Owner bit 0 = host, 1 = lance */
#define T_ERR           0x4000  /* Error Summary */
#define T_ADD_FCS       0x2000  /* More the 1 retry needed to Xmit */
#define T_MORE          0x1000  /* >1 retry to transmit packet */
#define T_ONE           0x0800  /* 1 try needed to transmit the packet */
#define T_DEF           0x0400  /* Deferred */
#define T_STP       0x02000000  /* Start of Packet */
#define T_ENP       0x01000000  /* End of Packet */
#define T_FLAGS     0xff000000  /* TX Flags Field */

/*
** Transmit Message Descriptor 3 (TMD3) bit definitions.
*/

#define TMD3_BUFF    0x8000     /* BUFFer error */
#define TMD3_UFLO    0x4000     /* UnderFLOw error */
#define TMD3_RES     0x2000     /* REServed */
#define TMD3_LCOL    0x1000     /* Late COLlision */
#define TMD3_LCAR    0x0800     /* Loss of CARrier */
#define TMD3_RTRY    0x0400     /* ReTRY error */

/*
** Ethernet PROM defines
*/
#define PROBE_LENGTH    32

/*
** Set the number of Tx and Rx buffers. Ensure that the memory requested
** here is <= to the amount of shared memory set up by the board switches.
** The number of descriptors MUST BE A POWER OF 2.
**
** total_memory = NUM_RX_DESC*(8+RX_BUFF_SZ) + NUM_TX_DESC*(8+TX_BUFF_SZ)
*/
#define NUM_RX_DESC     2               /* Number of RX descriptors */
#define NUM_TX_DESC     2               /* Number of TX descriptors */
#define RX_BUFF_SZ      1536            /* Buffer size for each Rx buffer */
#define TX_BUFF_SZ      1536            /* Buffer size for each Tx buffer */

/*
** ISA Bus defines
*/
#define DEPCA_IO_PORTS  {0x300, 0x200, 0}

#ifndef DEPCA_MODEL
#define DEPCA_MODEL     DEPCA
#endif

static enum {
        DEPCA, DE100, DE101, DE200, DE201, DE202, DE210, DE212, DE422, unknown
} adapter = DEPCA_MODEL;

/*
** Name <-> Adapter mapping
*/

static char *adapter_name[] = {
        "DEPCA",
        "DE100","DE101",
        "DE200","DE201","DE202",
        "DE210","DE212",
        "DE422",
        ""
};

#ifndef DEPCA_RAM_BASE
#define DEPCA_RAM_BASE  0xd0000
#endif

/*
** Memory Alignment. Each descriptor is 4 longwords long. To force a
** particular alignment on the TX descriptor, adjust DESC_SKIP_LEN and
** DESC_ALIGN. ALIGN aligns the start address of the private memory area
** and hence the RX descriptor ring's first entry. 
*/
#define ALIGN4      ((u32)4 - 1)       /* 1 longword align */
#define ALIGN8      ((u32)8 - 1)       /* 2 longword (quadword) align */
#define ALIGN         ALIGN8              /* Keep the LANCE happy... */

typedef long            s32;
typedef unsigned long   u32;
typedef short           s16;
typedef unsigned short  u16;
typedef char            s8;
typedef unsigned char   u8;

/*
** The DEPCA Rx and Tx ring descriptors. 
*/
struct depca_rx_desc {
    volatile s32 base;
    s16 buf_length;             /* This length is negative 2's complement! */
    s16 msg_length;             /* This length is "normal". */
};

struct depca_tx_desc {
    volatile s32 base;
    s16 length;                 /* This length is negative 2's complement! */
    s16 misc;                   /* Errors and TDR info */
};

#define LA_MASK 0x0000ffff      /* LANCE address mask for mapping network RAM
                                   to LANCE memory address space */

/*
** The Lance initialization block, described in databook, in common memory.
*/
struct depca_init {
    u16 mode;                   /* Mode register */
    u8  phys_addr[ETH_ALEN];    /* Physical ethernet address */
    u8  mcast_table[8];         /* Multicast Hash Table. */
    u32 rx_ring;                /* Rx ring base pointer & ring length */
    u32 tx_ring;                /* Tx ring base pointer & ring length */
};

struct depca_private {
        struct depca_rx_desc    *rx_ring;
        struct depca_tx_desc    *tx_ring;
        struct depca_init       init_block;     /* Shadow init block */
        char                    *rx_memcpy[NUM_RX_DESC];
        char                    *tx_memcpy[NUM_TX_DESC];
        u32                     bus_offset;     /* ISA bus address offset */
        u32                     sh_mem;         /* address of shared mem */
        u32                     dma_buffs;      /* Rx & Tx buffer start */
        int                     rx_cur, tx_cur; /* Next free ring entry */
        int                     txRingMask, rxRingMask;
        s32                     rx_rlen, tx_rlen;
        /* log2([rt]xRingMask+1) for the descriptors */
};

static Address          mem_start = DEPCA_RAM_BASE;
static Address          mem_len, offset;
static unsigned short   ioaddr = 0;
static struct depca_private     lp;

/*
** Miscellaneous defines...
*/
#define STOP_DEPCA \
    outw(CSR0, DEPCA_ADDR);\
    outw(STOP, DEPCA_DATA)

/* Initialize the lance Rx and Tx descriptor rings. */
static void depca_init_ring(struct nic *nic)
{
        int     i;
        u32     p;

        lp.rx_cur = lp.tx_cur = 0;
        /* Initialize the base addresses and length of each buffer in the ring */
        for (i = 0; i <= lp.rxRingMask; i++) {
                writel((p = lp.dma_buffs + i * RX_BUFF_SZ) | R_OWN, &lp.rx_ring[i].base);
                writew(-RX_BUFF_SZ, &lp.rx_ring[i].buf_length);
                lp.rx_memcpy[i] = (char *) (p + lp.bus_offset);
        }
        for (i = 0; i <= lp.txRingMask; i++) {
                writel((p = lp.dma_buffs + (i + lp.txRingMask + 1) * TX_BUFF_SZ) & 0x00ffffff, &lp.tx_ring[i].base);
                lp.tx_memcpy[i] = (char *) (p + lp.bus_offset);
        }

        /* Set up the initialization block */
        lp.init_block.rx_ring = ((u32) ((u32) lp.rx_ring) & LA_MASK) | lp.rx_rlen;
        lp.init_block.tx_ring = ((u32) ((u32) lp.tx_ring) & LA_MASK) | lp.tx_rlen;
        for (i = 0; i < ETH_ALEN; i++)
                lp.init_block.phys_addr[i] = nic->node_addr[i];
        lp.init_block.mode = 0x0000;    /* Enable the Tx and Rx */
        memset(lp.init_block.mcast_table, 0, sizeof(lp.init_block.mcast_table));
}

static void LoadCSRs(void)
{
        outw(CSR1, DEPCA_ADDR); /* initialisation block address LSW */
        outw((u16) (lp.sh_mem & LA_MASK), DEPCA_DATA);
        outw(CSR2, DEPCA_ADDR); /* initialisation block address MSW */
        outw((u16) ((lp.sh_mem & LA_MASK) >> 16), DEPCA_DATA);
        outw(CSR3, DEPCA_ADDR); /* ALE control */
        outw(ACON, DEPCA_DATA);
        outw(CSR0, DEPCA_ADDR); /* Point back to CSR0 */
}

static int InitRestartDepca(void)
{
        int             i;

        /* Copy the shadow init_block to shared memory */
        memcpy_toio((char *)lp.sh_mem, &lp.init_block, sizeof(struct depca_init));
        outw(CSR0, DEPCA_ADDR);         /* point back to CSR0 */
        outw(INIT, DEPCA_DATA);         /* initialise DEPCA */

        for (i = 0; i < 100 && !(inw(DEPCA_DATA) & IDON); i++)
                ;
        if (i < 100) {
                /* clear IDON by writing a 1, and start LANCE */
                outw(IDON | STRT, DEPCA_DATA);
        } else {
                printf("DEPCA not initialised\n");
                return (1);
        }
        return (0);
}

/**************************************************************************
RESET - Reset adapter
***************************************************************************/
static void depca_reset(struct nic *nic)
{
        s16     nicsr;
        int     i, j;

        STOP_DEPCA;
        nicsr = inb(DEPCA_NICSR);
        nicsr = ((nicsr & ~SHE & ~RBE & ~IEN) | IM);
        outb(nicsr, DEPCA_NICSR);
        if (inw(DEPCA_DATA) != STOP)
        {
                printf("depca: Cannot stop NIC\n");
                return;
        }

        /* Initialisation block */
        lp.sh_mem = mem_start;
        mem_start += sizeof(struct depca_init);
        /* Tx & Rx descriptors (aligned to a quadword boundary) */
        mem_start = (mem_start + ALIGN) & ~ALIGN;
        lp.rx_ring = (struct depca_rx_desc *) mem_start;
        mem_start += (sizeof(struct depca_rx_desc) * NUM_RX_DESC);
        lp.tx_ring = (struct depca_tx_desc *) mem_start;
        mem_start += (sizeof(struct depca_tx_desc) * NUM_TX_DESC);

        lp.bus_offset = mem_start & 0x00ff0000;
        /* LANCE re-mapped start address */
        lp.dma_buffs = mem_start & LA_MASK;

        /* Finish initialising the ring information. */
        lp.rxRingMask = NUM_RX_DESC - 1;
        lp.txRingMask = NUM_TX_DESC - 1;

        /* Calculate Tx/Rx RLEN size for the descriptors. */
        for (i = 0, j = lp.rxRingMask; j > 0; i++) {
                j >>= 1;
        }
        lp.rx_rlen = (s32) (i << 29);
        for (i = 0, j = lp.txRingMask; j > 0; i++) {
                j >>= 1;
        }
        lp.tx_rlen = (s32) (i << 29);

        /* Load the initialisation block */
        depca_init_ring(nic);
        LoadCSRs();
        InitRestartDepca();
}

/**************************************************************************
POLL - Wait for a frame
***************************************************************************/
static int depca_poll(struct nic *nic)
{
        int             entry;
        u32             status;

        entry = lp.rx_cur;
        if ((status = readl(&lp.rx_ring[entry].base) & R_OWN))
                return (0);
        memcpy(nic->packet, lp.rx_memcpy[entry], nic->packetlen = lp.rx_ring[entry].msg_length);
        lp.rx_ring[entry].base |= R_OWN;
        lp.rx_cur = (++lp.rx_cur) & lp.rxRingMask;
        return (1);
}

/**************************************************************************
TRANSMIT - Transmit a frame
***************************************************************************/
static void depca_transmit(
        struct nic *nic,
        const char *d,                  /* Destination */
        unsigned int t,                 /* Type */
        unsigned int s,                 /* size */
        const char *p)                  /* Packet */
{
        int             entry, len;
        char            *mem;

        /* send the packet to destination */
        /*
        ** Caution: the right order is important here... dont
        ** setup the ownership rights until all the other
        ** information is in place
        */
        mem = lp.tx_memcpy[entry = lp.tx_cur];
        memcpy_toio(mem, d, ETH_ALEN);
        memcpy_toio(mem + ETH_ALEN, nic->node_addr, ETH_ALEN);
        mem[ETH_ALEN * 2] = t >> 8;
        mem[ETH_ALEN * 2 + 1] = t;
        memcpy_toio(mem + ETH_HLEN, p, s);
        s += ETH_HLEN;
        len = (s < ETH_ZLEN ? ETH_ZLEN : s);
        /* clean out flags */
        writel(readl(&lp.tx_ring[entry].base) & ~T_FLAGS, &lp.tx_ring[entry].base);
        /* clears other error flags */
        writew(0x0000, &lp.tx_ring[entry].misc);
        /* packet length in buffer */
        writew(-len, &lp.tx_ring[entry].length);
        /* start and end of packet, ownership */
        writel(readl(&lp.tx_ring[entry].base) | (T_STP|T_ENP|T_OWN), &lp.tx_ring[entry].base);
        /* update current pointers */
        lp.tx_cur = (++lp.tx_cur) & lp.txRingMask;
}

/**************************************************************************
DISABLE - Turn off ethernet interface
***************************************************************************/
static void depca_disable(struct nic *nic)
{
        STOP_DEPCA;
}

/*
** Look for a special sequence in the Ethernet station address PROM that
** is common across all DEPCA products. Note that the original DEPCA needs
** its ROM address counter to be initialized and enabled. Only enable
** if the first address octet is a 0x08 - this minimises the chances of
** messing around with some other hardware, but it assumes that this DEPCA
** card initialized itself correctly.
**
** Search the Ethernet address ROM for the signature. Since the ROM address
** counter can start at an arbitrary point, the search must include the entire
** probe sequence length plus the (length_of_the_signature - 1).
** Stop the search IMMEDIATELY after the signature is found so that the
** PROM address counter is correctly positioned at the start of the
** ethernet address for later read out.
*/
static int depca_probe1(struct nic *nic)
{
        u8      data, nicsr;
        /* This is only correct for little endian machines, but then
           Etherboot doesn't work on anything but a PC */
        u8      sig[] = { 0xFF, 0x00, 0x55, 0xAA, 0xFF, 0x00, 0x55, 0xAA };
        int     i, j;
        long    sum, chksum;

        data = inb(DEPCA_PROM);         /* clear counter on DEPCA */
        data = inb(DEPCA_PROM);         /* read data */
        if (data == 0x8) {
                nicsr = inb(DEPCA_NICSR);
                nicsr |= AAC;
                outb(nicsr, DEPCA_NICSR);
        }
        for (i = 0, j = 0; j < (int)sizeof(sig) && i < PROBE_LENGTH+((int)sizeof(sig))-1; ++i) {
                data = inb(DEPCA_PROM);
                if (data == sig[j])             /* track signature */
                        ++j;
                else
                        j = (data == sig[0]) ? 1 : 0;
        }
        if (j != sizeof(sig))
                return (0);
        /* put the card in its initial state */
        STOP_DEPCA;
        nicsr = ((inb(DEPCA_NICSR) & ~SHE & ~RBE & ~IEN) | IM);
        outb(nicsr, DEPCA_NICSR);
        if (inw(DEPCA_DATA) != STOP)
                return (0);
        memcpy((char *)mem_start, sig, sizeof(sig));
        if (memcmp((char *)mem_start, sig, sizeof(sig)) != 0)
                return (0);
        for (i = 0, j = 0, sum = 0; j < 3; j++) {
                sum <<= 1;
                if (sum > 0xFFFF)
                        sum -= 0xFFFF;
                sum += (u8)(nic->node_addr[i++] = inb(DEPCA_PROM));
                sum += (u16)((nic->node_addr[i++] = inb(DEPCA_PROM)) << 8);
                if (sum > 0xFFFF)
                        sum -= 0xFFFF;
        }
        if (sum == 0xFFFF)
                sum = 0;
        chksum = (u8)inb(DEPCA_PROM);
        chksum |= (u16)(inb(DEPCA_PROM) << 8);
        mem_len = (adapter == DEPCA) ? (48 << 10) : (64 << 10);
        offset = 0;
        if (nicsr & BUF) {
                offset = 0x8000;
                nicsr &= ~BS;
                mem_len -= (32 << 10);
        }
        if (adapter != DEPCA)   /* enable shadow RAM */
                outb(nicsr |= SHE, DEPCA_NICSR);
        printf("%s base %#hX, memory [%#hX-%#hX], addr %!",
                adapter_name[adapter], ioaddr, mem_start, mem_start + mem_len,
                nic->node_addr);
        if (sum != chksum)
                printf(" (bad checksum)");
        putchar('\n');
        return (1);
}

/**************************************************************************
PROBE - Look for an adapter, this routine's visible to the outside
***************************************************************************/
struct nic *depca_probe(struct nic *nic, unsigned short *probe_addrs)
{
        static unsigned short   base[] = DEPCA_IO_PORTS;
        int                     i;

        if (probe_addrs == 0 || probe_addrs[0] == 0)
                probe_addrs = base;     /* Use defaults */
        for (i = 0; (ioaddr = base[i]) != 0; ++i) {
                if (depca_probe1(nic))
                        break;
        }
        if (ioaddr == 0)
                return (0);
        depca_reset(nic);
        /* point to NIC specific routines */
        nic->reset = depca_reset;
        nic->poll = depca_poll;
        nic->transmit = depca_transmit;
        nic->disable = depca_disable;
        return (nic);
}