[CPUFREQ] Misc cleanups in ondemand.

[linux-2.6/next.git] / drivers / serial / at91_serial.c

/*
 *  linux/drivers/char/at91_serial.c
 *
 *  Driver for Atmel AT91RM9200 Serial ports
 *  Copyright (C) 2003 Rick Bronson
 *
 *  Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/tty_flip.h>
#include <linux/platform_device.h>

#include <asm/io.h>

#include <asm/arch/at91rm9200_usart.h>
#include <asm/arch/at91rm9200_pdc.h>
#include <asm/mach/serial_at91.h>
#include <asm/arch/board.h>
#include <asm/arch/system.h>

#if defined(CONFIG_SERIAL_AT91_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>

#ifdef CONFIG_SERIAL_AT91_TTYAT

/* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
 * should coexist with the 8250 driver, such as if we have an external 16C550
 * UART. */
#define SERIAL_AT91_MAJOR       204
#define MINOR_START             154
#define AT91_DEVICENAME         "ttyAT"

#else

/* Use device name ttyS, major 4, minor 64-68.  This is the usual serial port
 * name, but it is legally reserved for the 8250 driver. */
#define SERIAL_AT91_MAJOR       TTY_MAJOR
#define MINOR_START             64
#define AT91_DEVICENAME         "ttyS"

#endif

#define AT91_ISR_PASS_LIMIT     256

#define UART_PUT_CR(port,v)     writel(v, (port)->membase + AT91_US_CR)
#define UART_GET_MR(port)       readl((port)->membase + AT91_US_MR)
#define UART_PUT_MR(port,v)     writel(v, (port)->membase + AT91_US_MR)
#define UART_PUT_IER(port,v)    writel(v, (port)->membase + AT91_US_IER)
#define UART_PUT_IDR(port,v)    writel(v, (port)->membase + AT91_US_IDR)
#define UART_GET_IMR(port)      readl((port)->membase + AT91_US_IMR)
#define UART_GET_CSR(port)      readl((port)->membase + AT91_US_CSR)
#define UART_GET_CHAR(port)     readl((port)->membase + AT91_US_RHR)
#define UART_PUT_CHAR(port,v)   writel(v, (port)->membase + AT91_US_THR)
#define UART_GET_BRGR(port)     readl((port)->membase + AT91_US_BRGR)
#define UART_PUT_BRGR(port,v)   writel(v, (port)->membase + AT91_US_BRGR)
#define UART_PUT_RTOR(port,v)   writel(v, (port)->membase + AT91_US_RTOR)

// #define UART_GET_CR(port)    readl((port)->membase + AT91_US_CR)             // is write-only

 /* PDC registers */
#define UART_PUT_PTCR(port,v)   writel(v, (port)->membase + AT91_PDC_PTCR)
#define UART_GET_PTSR(port)     readl((port)->membase + AT91_PDC_PTSR)

#define UART_PUT_RPR(port,v)    writel(v, (port)->membase + AT91_PDC_RPR)
#define UART_GET_RPR(port)      readl((port)->membase + AT91_PDC_RPR)
#define UART_PUT_RCR(port,v)    writel(v, (port)->membase + AT91_PDC_RCR)
#define UART_PUT_RNPR(port,v)   writel(v, (port)->membase + AT91_PDC_RNPR)
#define UART_PUT_RNCR(port,v)   writel(v, (port)->membase + AT91_PDC_RNCR)

#define UART_PUT_TPR(port,v)    writel(v, (port)->membase + AT91_PDC_TPR)
#define UART_PUT_TCR(port,v)    writel(v, (port)->membase + AT91_PDC_TCR)
//#define UART_PUT_TNPR(port,v) writel(v, (port)->membase + AT91_PDC_TNPR)
//#define UART_PUT_TNCR(port,v) writel(v, (port)->membase + AT91_PDC_TNCR)

static int (*at91_open)(struct uart_port *);
static void (*at91_close)(struct uart_port *);

/*
 * We wrap our port structure around the generic uart_port.
 */
struct at91_uart_port {
        struct uart_port        uart;           /* uart */
        struct clk              *clk;           /* uart clock */
        unsigned short          suspended;      /* is port suspended? */
};

static struct at91_uart_port at91_ports[AT91_NR_UART];

#ifdef SUPPORT_SYSRQ
static struct console at91_console;
#endif

/*
 * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
 */
static u_int at91_tx_empty(struct uart_port *port)
{
        return (UART_GET_CSR(port) & AT91_US_TXEMPTY) ? TIOCSER_TEMT : 0;
}

/*
 * Set state of the modem control output lines
 */
static void at91_set_mctrl(struct uart_port *port, u_int mctrl)
{
        unsigned int control = 0;
        unsigned int mode;

        if (arch_identify() == ARCH_ID_AT91RM9200) {
                /*
                 * AT91RM9200 Errata #39: RTS0 is not internally connected to PA21.
                 *  We need to drive the pin manually.
                 */
                if (port->mapbase == AT91_BASE_US0) {
                        if (mctrl & TIOCM_RTS)
                                at91_sys_write(AT91_PIOA + PIO_CODR, AT91_PA21_RTS0);
                        else
                                at91_sys_write(AT91_PIOA + PIO_SODR, AT91_PA21_RTS0);
                }
        }

        if (mctrl & TIOCM_RTS)
                control |= AT91_US_RTSEN;
        else
                control |= AT91_US_RTSDIS;

        if (mctrl & TIOCM_DTR)
                control |= AT91_US_DTREN;
        else
                control |= AT91_US_DTRDIS;

        UART_PUT_CR(port, control);

        /* Local loopback mode? */
        mode = UART_GET_MR(port) & ~AT91_US_CHMODE;
        if (mctrl & TIOCM_LOOP)
                mode |= AT91_US_CHMODE_LOC_LOOP;
        else
                mode |= AT91_US_CHMODE_NORMAL;
        UART_PUT_MR(port, mode);
}

/*
 * Get state of the modem control input lines
 */
static u_int at91_get_mctrl(struct uart_port *port)
{
        unsigned int status, ret = 0;

        status = UART_GET_CSR(port);

        /*
         * The control signals are active low.
         */
        if (!(status & AT91_US_DCD))
                ret |= TIOCM_CD;
        if (!(status & AT91_US_CTS))
                ret |= TIOCM_CTS;
        if (!(status & AT91_US_DSR))
                ret |= TIOCM_DSR;
        if (!(status & AT91_US_RI))
                ret |= TIOCM_RI;

        return ret;
}

/*
 * Stop transmitting.
 */
static void at91_stop_tx(struct uart_port *port)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        UART_PUT_IDR(port, AT91_US_TXRDY);
}

/*
 * Start transmitting.
 */
static void at91_start_tx(struct uart_port *port)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        UART_PUT_IER(port, AT91_US_TXRDY);
}

/*
 * Stop receiving - port is in process of being closed.
 */
static void at91_stop_rx(struct uart_port *port)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        UART_PUT_IDR(port, AT91_US_RXRDY);
}

/*
 * Enable modem status interrupts
 */
static void at91_enable_ms(struct uart_port *port)
{
        UART_PUT_IER(port, AT91_US_RIIC | AT91_US_DSRIC | AT91_US_DCDIC | AT91_US_CTSIC);
}

/*
 * Control the transmission of a break signal
 */
static void at91_break_ctl(struct uart_port *port, int break_state)
{
        if (break_state != 0)
                UART_PUT_CR(port, AT91_US_STTBRK);      /* start break */
        else
                UART_PUT_CR(port, AT91_US_STPBRK);      /* stop break */
}

/*
 * Characters received (called from interrupt handler)
 */
static void at91_rx_chars(struct uart_port *port, struct pt_regs *regs)
{
        struct tty_struct *tty = port->info->tty;
        unsigned int status, ch, flg;

        status = UART_GET_CSR(port);
        while (status & AT91_US_RXRDY) {
                ch = UART_GET_CHAR(port);

                port->icount.rx++;

                flg = TTY_NORMAL;

                /*
                 * note that the error handling code is
                 * out of the main execution path
                 */
                if (unlikely(status & (AT91_US_PARE | AT91_US_FRAME | AT91_US_OVRE | AT91_US_RXBRK))) {
                        UART_PUT_CR(port, AT91_US_RSTSTA);      /* clear error */
                        if (status & AT91_US_RXBRK) {
                                status &= ~(AT91_US_PARE | AT91_US_FRAME);      /* ignore side-effect */
                                port->icount.brk++;
                                if (uart_handle_break(port))
                                        goto ignore_char;
                        }
                        if (status & AT91_US_PARE)
                                port->icount.parity++;
                        if (status & AT91_US_FRAME)
                                port->icount.frame++;
                        if (status & AT91_US_OVRE)
                                port->icount.overrun++;

                        status &= port->read_status_mask;

                        if (status & AT91_US_RXBRK)
                                flg = TTY_BREAK;
                        else if (status & AT91_US_PARE)
                                flg = TTY_PARITY;
                        else if (status & AT91_US_FRAME)
                                flg = TTY_FRAME;
                }

                if (uart_handle_sysrq_char(port, ch, regs))
                        goto ignore_char;

                uart_insert_char(port, status, AT91_US_OVRE, ch, flg);

        ignore_char:
                status = UART_GET_CSR(port);
        }

        tty_flip_buffer_push(tty);
}

/*
 * Transmit characters (called from interrupt handler)
 */
static void at91_tx_chars(struct uart_port *port)
{
        struct circ_buf *xmit = &port->info->xmit;

        if (port->x_char) {
                UART_PUT_CHAR(port, port->x_char);
                port->icount.tx++;
                port->x_char = 0;
                return;
        }
        if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
                at91_stop_tx(port);
                return;
        }

        while (UART_GET_CSR(port) & AT91_US_TXRDY) {
                UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
                if (uart_circ_empty(xmit))
                        break;
        }

        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                uart_write_wakeup(port);

        if (uart_circ_empty(xmit))
                at91_stop_tx(port);
}

/*
 * Interrupt handler
 */
static irqreturn_t at91_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
        struct uart_port *port = dev_id;
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;
        unsigned int status, pending, pass_counter = 0;

        status = UART_GET_CSR(port);
        pending = status & UART_GET_IMR(port);
        while (pending) {
                /* Interrupt receive */
                if (pending & AT91_US_RXRDY)
                        at91_rx_chars(port, regs);

                // TODO: All reads to CSR will clear these interrupts!
                if (pending & AT91_US_RIIC) port->icount.rng++;
                if (pending & AT91_US_DSRIC) port->icount.dsr++;
                if (pending & AT91_US_DCDIC)
                        uart_handle_dcd_change(port, !(status & AT91_US_DCD));
                if (pending & AT91_US_CTSIC)
                        uart_handle_cts_change(port, !(status & AT91_US_CTS));
                if (pending & (AT91_US_RIIC | AT91_US_DSRIC | AT91_US_DCDIC | AT91_US_CTSIC))
                        wake_up_interruptible(&port->info->delta_msr_wait);

                /* Interrupt transmit */
                if (pending & AT91_US_TXRDY)
                        at91_tx_chars(port);

                if (pass_counter++ > AT91_ISR_PASS_LIMIT)
                        break;

                status = UART_GET_CSR(port);
                pending = status & UART_GET_IMR(port);
        }
        return IRQ_HANDLED;
}

/*
 * Perform initialization and enable port for reception
 */
static int at91_startup(struct uart_port *port)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;
        int retval;

        /*
         * Ensure that no interrupts are enabled otherwise when
         * request_irq() is called we could get stuck trying to
         * handle an unexpected interrupt
         */
        UART_PUT_IDR(port, -1);

        /*
         * Allocate the IRQ
         */
        retval = request_irq(port->irq, at91_interrupt, SA_SHIRQ, "at91_serial", port);
        if (retval) {
                printk("at91_serial: at91_startup - Can't get irq\n");
                return retval;
        }

        /*
         * If there is a specific "open" function (to register
         * control line interrupts)
         */
        if (at91_open) {
                retval = at91_open(port);
                if (retval) {
                        free_irq(port->irq, port);
                        return retval;
                }
        }

        /*
         * Finally, enable the serial port
         */
        UART_PUT_CR(port, AT91_US_RSTSTA | AT91_US_RSTRX);
        UART_PUT_CR(port, AT91_US_TXEN | AT91_US_RXEN);         /* enable xmit & rcvr */

        UART_PUT_IER(port, AT91_US_RXRDY);              /* enable receive only */

        return 0;
}

/*
 * Disable the port
 */
static void at91_shutdown(struct uart_port *port)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        /*
         * Disable all interrupts, port and break condition.
         */
        UART_PUT_CR(port, AT91_US_RSTSTA);
        UART_PUT_IDR(port, -1);

        /*
         * Free the interrupt
         */
        free_irq(port->irq, port);

        /*
         * If there is a specific "close" function (to unregister
         * control line interrupts)
         */
        if (at91_close)
                at91_close(port);
}

/*
 * Power / Clock management.
 */
static void at91_serial_pm(struct uart_port *port, unsigned int state, unsigned int oldstate)
{
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        switch (state) {
                case 0:
                        /*
                         * Enable the peripheral clock for this serial port.
                         * This is called on uart_open() or a resume event.
                         */
                        clk_enable(at91_port->clk);
                        break;
                case 3:
                        /*
                         * Disable the peripheral clock for this serial port.
                         * This is called on uart_close() or a suspend event.
                         */
                        clk_disable(at91_port->clk);
                        break;
                default:
                        printk(KERN_ERR "at91_serial: unknown pm %d\n", state);
        }
}

/*
 * Change the port parameters
 */
static void at91_set_termios(struct uart_port *port, struct termios * termios, struct termios * old)
{
        unsigned long flags;
        unsigned int mode, imr, quot, baud;

        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
        quot = uart_get_divisor(port, baud);

        /* Get current mode register */
        mode = UART_GET_MR(port) & ~(AT91_US_CHRL | AT91_US_NBSTOP | AT91_US_PAR);

        /* byte size */
        switch (termios->c_cflag & CSIZE) {
        case CS5:
                mode |= AT91_US_CHRL_5;
                break;
        case CS6:
                mode |= AT91_US_CHRL_6;
                break;
        case CS7:
                mode |= AT91_US_CHRL_7;
                break;
        default:
                mode |= AT91_US_CHRL_8;
                break;
        }

        /* stop bits */
        if (termios->c_cflag & CSTOPB)
                mode |= AT91_US_NBSTOP_2;

        /* parity */
        if (termios->c_cflag & PARENB) {
                if (termios->c_cflag & CMSPAR) {                        /* Mark or Space parity */
                        if (termios->c_cflag & PARODD)
                                mode |= AT91_US_PAR_MARK;
                        else
                                mode |= AT91_US_PAR_SPACE;
                }
                else if (termios->c_cflag & PARODD)
                        mode |= AT91_US_PAR_ODD;
                else
                        mode |= AT91_US_PAR_EVEN;
        }
        else
                mode |= AT91_US_PAR_NONE;

        spin_lock_irqsave(&port->lock, flags);

        port->read_status_mask = AT91_US_OVRE;
        if (termios->c_iflag & INPCK)
                port->read_status_mask |= (AT91_US_FRAME | AT91_US_PARE);
        if (termios->c_iflag & (BRKINT | PARMRK))
                port->read_status_mask |= AT91_US_RXBRK;

        /*
         * Characters to ignore
         */
        port->ignore_status_mask = 0;
        if (termios->c_iflag & IGNPAR)
                port->ignore_status_mask |= (AT91_US_FRAME | AT91_US_PARE);
        if (termios->c_iflag & IGNBRK) {
                port->ignore_status_mask |= AT91_US_RXBRK;
                /*
                 * If we're ignoring parity and break indicators,
                 * ignore overruns too (for real raw support).
                 */
                if (termios->c_iflag & IGNPAR)
                        port->ignore_status_mask |= AT91_US_OVRE;
        }

        // TODO: Ignore all characters if CREAD is set.

        /* update the per-port timeout */
        uart_update_timeout(port, termios->c_cflag, baud);

        /* disable interrupts and drain transmitter */
        imr = UART_GET_IMR(port);       /* get interrupt mask */
        UART_PUT_IDR(port, -1);         /* disable all interrupts */
        while (!(UART_GET_CSR(port) & AT91_US_TXEMPTY)) { barrier(); }

        /* disable receiver and transmitter */
        UART_PUT_CR(port, AT91_US_TXDIS | AT91_US_RXDIS);

        /* set the parity, stop bits and data size */
        UART_PUT_MR(port, mode);

        /* set the baud rate */
        UART_PUT_BRGR(port, quot);
        UART_PUT_CR(port, AT91_US_RSTSTA | AT91_US_RSTRX);
        UART_PUT_CR(port, AT91_US_TXEN | AT91_US_RXEN);

        /* restore interrupts */
        UART_PUT_IER(port, imr);

        /* CTS flow-control and modem-status interrupts */
        if (UART_ENABLE_MS(port, termios->c_cflag))
                port->ops->enable_ms(port);

        spin_unlock_irqrestore(&port->lock, flags);
}

/*
 * Return string describing the specified port
 */
static const char *at91_type(struct uart_port *port)
{
        return (port->type == PORT_AT91) ? "AT91_SERIAL" : NULL;
}

/*
 * Release the memory region(s) being used by 'port'.
 */
static void at91_release_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        int size = pdev->resource[0].end - pdev->resource[0].start + 1;

        release_mem_region(port->mapbase, size);

        if (port->flags & UPF_IOREMAP) {
                iounmap(port->membase);
                port->membase = NULL;
        }
}

/*
 * Request the memory region(s) being used by 'port'.
 */
static int at91_request_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        int size = pdev->resource[0].end - pdev->resource[0].start + 1;

        if (!request_mem_region(port->mapbase, size, "at91_serial"))
                return -EBUSY;

        if (port->flags & UPF_IOREMAP) {
                port->membase = ioremap(port->mapbase, size);
                if (port->membase == NULL) {
                        release_mem_region(port->mapbase, size);
                        return -ENOMEM;
                }
        }

        return 0;
}

/*
 * Configure/autoconfigure the port.
 */
static void at91_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE) {
                port->type = PORT_AT91;
                at91_request_port(port);
        }
}

/*
 * Verify the new serial_struct (for TIOCSSERIAL).
 */
static int at91_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        int ret = 0;
        if (ser->type != PORT_UNKNOWN && ser->type != PORT_AT91)
                ret = -EINVAL;
        if (port->irq != ser->irq)
                ret = -EINVAL;
        if (ser->io_type != SERIAL_IO_MEM)
                ret = -EINVAL;
        if (port->uartclk / 16 != ser->baud_base)
                ret = -EINVAL;
        if ((void *)port->mapbase != ser->iomem_base)
                ret = -EINVAL;
        if (port->iobase != ser->port)
                ret = -EINVAL;
        if (ser->hub6 != 0)
                ret = -EINVAL;
        return ret;
}

static struct uart_ops at91_pops = {
        .tx_empty       = at91_tx_empty,
        .set_mctrl      = at91_set_mctrl,
        .get_mctrl      = at91_get_mctrl,
        .stop_tx        = at91_stop_tx,
        .start_tx       = at91_start_tx,
        .stop_rx        = at91_stop_rx,
        .enable_ms      = at91_enable_ms,
        .break_ctl      = at91_break_ctl,
        .startup        = at91_startup,
        .shutdown       = at91_shutdown,
        .set_termios    = at91_set_termios,
        .type           = at91_type,
        .release_port   = at91_release_port,
        .request_port   = at91_request_port,
        .config_port    = at91_config_port,
        .verify_port    = at91_verify_port,
        .pm             = at91_serial_pm,
};

/*
 * Configure the port from the platform device resource info.
 */
static void __devinit at91_init_port(struct at91_uart_port *at91_port, struct platform_device *pdev)
{
        struct uart_port *port = &at91_port->uart;
        struct at91_uart_data *data = pdev->dev.platform_data;

        port->iotype    = UPIO_MEM;
        port->flags     = UPF_BOOT_AUTOCONF;
        port->ops       = &at91_pops;
        port->fifosize  = 1;
        port->line      = pdev->id;
        port->dev       = &pdev->dev;

        port->mapbase   = pdev->resource[0].start;
        port->irq       = pdev->resource[1].start;

        if (port->mapbase == AT91_VA_BASE_SYS + AT91_DBGU)              /* Part of system perpherals - already mapped */
                port->membase = (void __iomem *) port->mapbase;
        else {
                port->flags     |= UPF_IOREMAP;
                port->membase   = NULL;
        }

        if (!at91_port->clk) {          /* for console, the clock could already be configured */
                at91_port->clk = clk_get(&pdev->dev, "usart");
                clk_enable(at91_port->clk);
                port->uartclk = clk_get_rate(at91_port->clk);
        }
}

/*
 * Register board-specific modem-control line handlers.
 */
void __init at91_register_uart_fns(struct at91_port_fns *fns)
{
        if (fns->enable_ms)
                at91_pops.enable_ms = fns->enable_ms;
        if (fns->get_mctrl)
                at91_pops.get_mctrl = fns->get_mctrl;
        if (fns->set_mctrl)
                at91_pops.set_mctrl = fns->set_mctrl;
        at91_open          = fns->open;
        at91_close         = fns->close;
        at91_pops.pm       = fns->pm;
        at91_pops.set_wake = fns->set_wake;
}


#ifdef CONFIG_SERIAL_AT91_CONSOLE
static void at91_console_putchar(struct uart_port *port, int ch)
{
        while (!(UART_GET_CSR(port) & AT91_US_TXRDY))
                barrier();
        UART_PUT_CHAR(port, ch);
}

/*
 * Interrupts are disabled on entering
 */
static void at91_console_write(struct console *co, const char *s, u_int count)
{
        struct uart_port *port = &at91_ports[co->index].uart;
        unsigned int status, imr;

        /*
         *      First, save IMR and then disable interrupts
         */
        imr = UART_GET_IMR(port);       /* get interrupt mask */
        UART_PUT_IDR(port, AT91_US_RXRDY | AT91_US_TXRDY);

        uart_console_write(port, s, count, at91_console_putchar);

        /*
         *      Finally, wait for transmitter to become empty
         *      and restore IMR
         */
        do {
                status = UART_GET_CSR(port);
        } while (!(status & AT91_US_TXRDY));
        UART_PUT_IER(port, imr);        /* set interrupts back the way they were */
}

/*
 * If the port was already initialised (eg, by a boot loader), try to determine
 * the current setup.
 */
static void __init at91_console_get_options(struct uart_port *port, int *baud, int *parity, int *bits)
{
        unsigned int mr, quot;

// TODO: CR is a write-only register
//      unsigned int cr;
//
//      cr = UART_GET_CR(port) & (AT91_US_RXEN | AT91_US_TXEN);
//      if (cr == (AT91_US_RXEN | AT91_US_TXEN)) {
//              /* ok, the port was enabled */
//      }

        mr = UART_GET_MR(port) & AT91_US_CHRL;
        if (mr == AT91_US_CHRL_8)
                *bits = 8;
        else
                *bits = 7;

        mr = UART_GET_MR(port) & AT91_US_PAR;
        if (mr == AT91_US_PAR_EVEN)
                *parity = 'e';
        else if (mr == AT91_US_PAR_ODD)
                *parity = 'o';

        quot = UART_GET_BRGR(port);
        *baud = port->uartclk / (16 * (quot));
}

static int __init at91_console_setup(struct console *co, char *options)
{
        struct uart_port *port = &at91_ports[co->index].uart;
        int baud = 115200;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (port->membase == 0)         /* Port not initialized yet - delay setup */
                return -ENODEV;

        UART_PUT_IDR(port, -1);                         /* disable interrupts */
        UART_PUT_CR(port, AT91_US_RSTSTA | AT91_US_RSTRX);
        UART_PUT_CR(port, AT91_US_TXEN | AT91_US_RXEN);

        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);
        else
                at91_console_get_options(port, &baud, &parity, &bits);

        return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver at91_uart;

static struct console at91_console = {
        .name           = AT91_DEVICENAME,
        .write          = at91_console_write,
        .device         = uart_console_device,
        .setup          = at91_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = -1,
        .data           = &at91_uart,
};

#define AT91_CONSOLE_DEVICE     &at91_console

/*
 * Early console initialization (before VM subsystem initialized).
 */
static int __init at91_console_init(void)
{
        if (at91_default_console_device) {
                add_preferred_console(AT91_DEVICENAME, at91_default_console_device->id, NULL);
                at91_init_port(&(at91_ports[at91_default_console_device->id]), at91_default_console_device);
                register_console(&at91_console);
        }

        return 0;
}
console_initcall(at91_console_init);

/*
 * Late console initialization.
 */
static int __init at91_late_console_init(void)
{
        if (at91_default_console_device && !(at91_console.flags & CON_ENABLED))
                register_console(&at91_console);

        return 0;
}
core_initcall(at91_late_console_init);

#else
#define AT91_CONSOLE_DEVICE     NULL
#endif

static struct uart_driver at91_uart = {
        .owner                  = THIS_MODULE,
        .driver_name            = "at91_serial",
        .dev_name               = AT91_DEVICENAME,
        .major                  = SERIAL_AT91_MAJOR,
        .minor                  = MINOR_START,
        .nr                     = AT91_NR_UART,
        .cons                   = AT91_CONSOLE_DEVICE,
};

#ifdef CONFIG_PM
static int at91_serial_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        if (device_may_wakeup(&pdev->dev) && !at91_suspend_entering_slow_clock())
                enable_irq_wake(port->irq);
        else {
                disable_irq_wake(port->irq);
                uart_suspend_port(&at91_uart, port);
                at91_port->suspended = 1;
        }

        return 0;
}

static int at91_serial_resume(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;

        if (at91_port->suspended) {
                uart_resume_port(&at91_uart, port);
                at91_port->suspended = 0;
        }

        return 0;
}
#else
#define at91_serial_suspend NULL
#define at91_serial_resume NULL
#endif

static int __devinit at91_serial_probe(struct platform_device *pdev)
{
        struct at91_uart_port *port;
        int ret;

        port = &at91_ports[pdev->id];
        at91_init_port(port, pdev);

        ret = uart_add_one_port(&at91_uart, &port->uart);
        if (!ret) {
                device_init_wakeup(&pdev->dev, 1);
                platform_set_drvdata(pdev, port);
        }

        return ret;
}

static int __devexit at91_serial_remove(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct at91_uart_port *at91_port = (struct at91_uart_port *) port;
        int ret = 0;

        clk_disable(at91_port->clk);
        clk_put(at91_port->clk);

        device_init_wakeup(&pdev->dev, 0);
        platform_set_drvdata(pdev, NULL);

        if (port) {
                ret = uart_remove_one_port(&at91_uart, port);
                kfree(port);
        }

        return ret;
}

static struct platform_driver at91_serial_driver = {
        .probe          = at91_serial_probe,
        .remove         = __devexit_p(at91_serial_remove),
        .suspend        = at91_serial_suspend,
        .resume         = at91_serial_resume,
        .driver         = {
                .name   = "at91_usart",
                .owner  = THIS_MODULE,
        },
};

static int __init at91_serial_init(void)
{
        int ret;

        ret = uart_register_driver(&at91_uart);
        if (ret)
                return ret;

        ret = platform_driver_register(&at91_serial_driver);
        if (ret)
                uart_unregister_driver(&at91_uart);

        return ret;
}

static void __exit at91_serial_exit(void)
{
        platform_driver_unregister(&at91_serial_driver);
        uart_unregister_driver(&at91_uart);
}

module_init(at91_serial_init);
module_exit(at91_serial_exit);

MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("AT91 generic serial port driver");
MODULE_LICENSE("GPL");