amiserial.c

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/*
 * Serial driver for the amiga builtin port.
 *
 * This code was created by taking serial.c version 4.30 from kernel
 * release 2.3.22, replacing all hardware related stuff with the
 * corresponding amiga hardware actions, and removing all irrelevant
 * code. As a consequence, it uses many of the constants and names
 * associated with the registers and bits of 16550 compatible UARTS -
 * but only to keep track of status, etc in the state variables. It
 * was done this was to make it easier to keep the code in line with
 * (non hardware specific) changes to serial.c.
 *
 * The port is registered with the tty driver as minor device 64, and
 * therefore other ports should should only use 65 upwards.
 *
 * Richard Lucock 28/12/99
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 
 *      1998, 1999  Theodore Ts'o
 *
 */

/*
 * Serial driver configuration section.  Here are the various options:
 *
 * SERIAL_PARANOIA_CHECK
 *      Check the magic number for the async_structure where
 *      ever possible.
 */

#include <linux/delay.h>

#undef SERIAL_PARANOIA_CHECK
#define SERIAL_DO_RESTART

/* Set of debugging defines */

#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW
#undef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT

/* Sanity checks */

#if defined(MODULE) && defined(SERIAL_DEBUG_MCOUNT)
#define DBG_CNT(s) printk("(%s): [%x] refc=%d, serc=%d, ttyc=%d -> %s\n", \
 tty->name, (info->tport.flags), serial_driver->refcount,info->count,tty->count,s)
#else
#define DBG_CNT(s)
#endif

/*
 * End of serial driver configuration section.
 */

#include <linux/module.h>

#include <linux/types.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
static char *serial_version = "4.30";

#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/circ_buf.h>
#include <linux/console.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/init.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>

#include <asm/setup.h>


#include <asm/irq.h>

#include <asm/amigahw.h>
#include <asm/amigaints.h>

struct serial_state {
    struct tty_port     tport;
    struct circ_buf     xmit;
    struct async_icount icount;

    unsigned long       port;
    int         baud_base;
    int         xmit_fifo_size;
    int         custom_divisor;
    int         read_status_mask;
    int         ignore_status_mask;
    int         timeout;
    int         quot;
    int         IER;    /* Interrupt Enable Register */
    int         MCR;    /* Modem control register */
    int         x_char; /* xon/xoff character */
};

#define custom amiga_custom
static char *serial_name = "Amiga-builtin serial driver";

static struct tty_driver *serial_driver;

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

static unsigned char current_ctl_bits;

static void change_speed(struct tty_struct *tty, struct serial_state *info,
        struct ktermios *old);
static void rs_wait_until_sent(struct tty_struct *tty, int timeout);


static struct serial_state rs_table[1];

#define NR_PORTS ARRAY_SIZE(rs_table)

#include <asm/uaccess.h>

#define serial_isroot() (capable(CAP_SYS_ADMIN))


static inline int serial_paranoia_check(struct serial_state *info,
                    char *name, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
    static const char *badmagic =
        "Warning: bad magic number for serial struct (%s) in %s\n";
    static const char *badinfo =
        "Warning: null async_struct for (%s) in %s\n";

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

/* some serial hardware definitions */
#define SDR_OVRUN   (1<<15)
#define SDR_RBF     (1<<14)
#define SDR_TBE     (1<<13)
#define SDR_TSRE    (1<<12)

#define SERPER_PARENB    (1<<15)

#define AC_SETCLR   (1<<15)
#define AC_UARTBRK  (1<<11)

#define SER_DTR     (1<<7)
#define SER_RTS     (1<<6)
#define SER_DCD     (1<<5)
#define SER_CTS     (1<<4)
#define SER_DSR     (1<<3)

static __inline__ void rtsdtr_ctrl(int bits)
{
    ciab.pra = ((bits & (SER_RTS | SER_DTR)) ^ (SER_RTS | SER_DTR)) | (ciab.pra & ~(SER_RTS | SER_DTR));
}

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_stop"))
        return;

    local_irq_save(flags);
    if (info->IER & UART_IER_THRI) {
        info->IER &= ~UART_IER_THRI;
        /* disable Tx interrupt and remove any pending interrupts */
        custom.intena = IF_TBE;
        mb();
        custom.intreq = IF_TBE;
        mb();
    }
    local_irq_restore(flags);
}

static void rs_start(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_start"))
        return;

    local_irq_save(flags);
    if (info->xmit.head != info->xmit.tail
        && info->xmit.buf
        && !(info->IER & UART_IER_THRI)) {
        info->IER |= UART_IER_THRI;
        custom.intena = IF_SETCLR | IF_TBE;
        mb();
        /* set a pending Tx Interrupt, transmitter should restart now */
        custom.intreq = IF_SETCLR | IF_TBE;
        mb();
    }
    local_irq_restore(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_interrupt().  They were separated out for readability's sake.
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer serial.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 *              - Ted Ts'o ([email protected]), 7-Mar-93
 * -----------------------------------------------------------------------
 */

static void receive_chars(struct serial_state *info)
{
        int status;
    int serdatr;
    struct tty_struct *tty = info->tport.tty;
    unsigned char ch, flag;
    struct  async_icount *icount;
    int oe = 0;

    icount = &info->icount;

    status = UART_LSR_DR; /* We obviously have a character! */
    serdatr = custom.serdatr;
    mb();
    custom.intreq = IF_RBF;
    mb();

    if((serdatr & 0x1ff) == 0)
        status |= UART_LSR_BI;
    if(serdatr & SDR_OVRUN)
        status |= UART_LSR_OE;

    ch = serdatr & 0xff;
    icount->rx++;

#ifdef SERIAL_DEBUG_INTR
    printk("DR%02x:%02x...", ch, status);
#endif
    flag = TTY_NORMAL;

    /*
     * We don't handle parity or frame errors - but I have left
     * the code in, since I'm not sure that the errors can't be
     * detected.
     */

    if (status & (UART_LSR_BI | UART_LSR_PE |
              UART_LSR_FE | UART_LSR_OE)) {
      /*
       * For statistics only
       */
      if (status & UART_LSR_BI) {
        status &= ~(UART_LSR_FE | UART_LSR_PE);
        icount->brk++;
      } else if (status & UART_LSR_PE)
        icount->parity++;
      else if (status & UART_LSR_FE)
        icount->frame++;
      if (status & UART_LSR_OE)
        icount->overrun++;

      /*
       * Now check to see if character should be
       * ignored, and mask off conditions which
       * should be ignored.
       */
      if (status & info->ignore_status_mask)
        goto out;

      status &= info->read_status_mask;

      if (status & (UART_LSR_BI)) {
#ifdef SERIAL_DEBUG_INTR
        printk("handling break....");
#endif
        flag = TTY_BREAK;
        if (info->tport.flags & ASYNC_SAK)
          do_SAK(tty);
      } else if (status & UART_LSR_PE)
        flag = TTY_PARITY;
      else if (status & UART_LSR_FE)
        flag = TTY_FRAME;
      if (status & UART_LSR_OE) {
        /*
         * Overrun is special, since it's
         * reported immediately, and doesn't
         * affect the current character
         */
         oe = 1;
      }
    }
    tty_insert_flip_char(tty, ch, flag);
    if (oe == 1)
        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
    tty_flip_buffer_push(tty);
out:
    return;
}

static void transmit_chars(struct serial_state *info)
{
    custom.intreq = IF_TBE;
    mb();
    if (info->x_char) {
            custom.serdat = info->x_char | 0x100;
        mb();
        info->icount.tx++;
        info->x_char = 0;
        return;
    }
    if (info->xmit.head == info->xmit.tail
        || info->tport.tty->stopped
        || info->tport.tty->hw_stopped) {
        info->IER &= ~UART_IER_THRI;
            custom.intena = IF_TBE;
        mb();
        return;
    }

    custom.serdat = info->xmit.buf[info->xmit.tail++] | 0x100;
    mb();
    info->xmit.tail = info->xmit.tail & (SERIAL_XMIT_SIZE-1);
    info->icount.tx++;

    if (CIRC_CNT(info->xmit.head,
             info->xmit.tail,
             SERIAL_XMIT_SIZE) < WAKEUP_CHARS)
        tty_wakeup(info->tport.tty);

#ifdef SERIAL_DEBUG_INTR
    printk("THRE...");
#endif
    if (info->xmit.head == info->xmit.tail) {
            custom.intena = IF_TBE;
        mb();
        info->IER &= ~UART_IER_THRI;
    }
}

static void check_modem_status(struct serial_state *info)
{
    struct tty_port *port = &info->tport;
    unsigned char status = ciab.pra & (SER_DCD | SER_CTS | SER_DSR);
    unsigned char dstatus;
    struct  async_icount *icount;

    /* Determine bits that have changed */
    dstatus = status ^ current_ctl_bits;
    current_ctl_bits = status;

    if (dstatus) {
        icount = &info->icount;
        /* update input line counters */
        if (dstatus & SER_DSR)
            icount->dsr++;
        if (dstatus & SER_DCD) {
            icount->dcd++;
#ifdef CONFIG_HARD_PPS
            if ((port->flags & ASYNC_HARDPPS_CD) &&
                !(status & SER_DCD))
                hardpps();
#endif
        }
        if (dstatus & SER_CTS)
            icount->cts++;
        wake_up_interruptible(&port->delta_msr_wait);
    }

    if ((port->flags & ASYNC_CHECK_CD) && (dstatus & SER_DCD)) {
#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
        printk("ttyS%d CD now %s...", info->line,
               (!(status & SER_DCD)) ? "on" : "off");
#endif
        if (!(status & SER_DCD))
            wake_up_interruptible(&port->open_wait);
        else {
#ifdef SERIAL_DEBUG_OPEN
            printk("doing serial hangup...");
#endif
            if (port->tty)
                tty_hangup(port->tty);
        }
    }
    if (tty_port_cts_enabled(port)) {
        if (port->tty->hw_stopped) {
            if (!(status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
                printk("CTS tx start...");
#endif
                port->tty->hw_stopped = 0;
                info->IER |= UART_IER_THRI;
                custom.intena = IF_SETCLR | IF_TBE;
                mb();
                /* set a pending Tx Interrupt, transmitter should restart now */
                custom.intreq = IF_SETCLR | IF_TBE;
                mb();
                tty_wakeup(port->tty);
                return;
            }
        } else {
            if ((status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
                printk("CTS tx stop...");
#endif
                port->tty->hw_stopped = 1;
                info->IER &= ~UART_IER_THRI;
                /* disable Tx interrupt and remove any pending interrupts */
                custom.intena = IF_TBE;
                mb();
                custom.intreq = IF_TBE;
                mb();
            }
        }
    }
}

static irqreturn_t ser_vbl_int( int irq, void *data)
{
        /* vbl is just a periodic interrupt we tie into to update modem status */
    struct serial_state *info = data;
    /*
     * TBD - is it better to unregister from this interrupt or to
     * ignore it if MSI is clear ?
     */
    if(info->IER & UART_IER_MSI)
      check_modem_status(info);
    return IRQ_HANDLED;
}

static irqreturn_t ser_rx_int(int irq, void *dev_id)
{
    struct serial_state *info = dev_id;

#ifdef SERIAL_DEBUG_INTR
    printk("ser_rx_int...");
#endif

    if (!info->tport.tty)
        return IRQ_NONE;

    receive_chars(info);
#ifdef SERIAL_DEBUG_INTR
    printk("end.\n");
#endif
    return IRQ_HANDLED;
}

static irqreturn_t ser_tx_int(int irq, void *dev_id)
{
    struct serial_state *info = dev_id;

    if (custom.serdatr & SDR_TBE) {
#ifdef SERIAL_DEBUG_INTR
      printk("ser_tx_int...");
#endif

      if (!info->tport.tty)
        return IRQ_NONE;

      transmit_chars(info);
#ifdef SERIAL_DEBUG_INTR
      printk("end.\n");
#endif
    }
    return IRQ_HANDLED;
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * ---------------------------------------------------------------
 * Low level utility subroutines for the serial driver:  routines to
 * figure out the appropriate timeout for an interrupt chain, routines
 * to initialize and startup a serial port, and routines to shutdown a
 * serial port.  Useful stuff like that.
 * ---------------------------------------------------------------
 */

static int startup(struct tty_struct *tty, struct serial_state *info)
{
    struct tty_port *port = &info->tport;
    unsigned long flags;
    int retval=0;
    unsigned long page;

    page = get_zeroed_page(GFP_KERNEL);
    if (!page)
        return -ENOMEM;

    local_irq_save(flags);

    if (port->flags & ASYNC_INITIALIZED) {
        free_page(page);
        goto errout;
    }

    if (info->xmit.buf)
        free_page(page);
    else
        info->xmit.buf = (unsigned char *) page;

#ifdef SERIAL_DEBUG_OPEN
    printk("starting up ttys%d ...", info->line);
#endif

    /* Clear anything in the input buffer */

    custom.intreq = IF_RBF;
    mb();

    retval = request_irq(IRQ_AMIGA_VERTB, ser_vbl_int, 0, "serial status", info);
    if (retval) {
      if (serial_isroot()) {
          set_bit(TTY_IO_ERROR, &tty->flags);
        retval = 0;
      }
      goto errout;
    }

    /* enable both Rx and Tx interrupts */
    custom.intena = IF_SETCLR | IF_RBF | IF_TBE;
    mb();
    info->IER = UART_IER_MSI;

    /* remember current state of the DCD and CTS bits */
    current_ctl_bits = ciab.pra & (SER_DCD | SER_CTS | SER_DSR);

    info->MCR = 0;
    if (C_BAUD(tty))
      info->MCR = SER_DTR | SER_RTS;
    rtsdtr_ctrl(info->MCR);

    clear_bit(TTY_IO_ERROR, &tty->flags);
    info->xmit.head = info->xmit.tail = 0;

    /*
     * Set up the tty->alt_speed kludge
     */
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
        tty->alt_speed = 57600;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
        tty->alt_speed = 115200;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
        tty->alt_speed = 230400;
    if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
        tty->alt_speed = 460800;

    /*
     * and set the speed of the serial port
     */
    change_speed(tty, info, NULL);

    port->flags |= ASYNC_INITIALIZED;
    local_irq_restore(flags);
    return 0;

errout:
    local_irq_restore(flags);
    return retval;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(struct tty_struct *tty, struct serial_state *info)
{
    unsigned long   flags;
    struct serial_state *state;

    if (!(info->tport.flags & ASYNC_INITIALIZED))
        return;

    state = info;

#ifdef SERIAL_DEBUG_OPEN
    printk("Shutting down serial port %d ....\n", info->line);
#endif

    local_irq_save(flags); /* Disable interrupts */

    /*
     * clear delta_msr_wait queue to avoid mem leaks: we may free the irq
     * here so the queue might never be waken up
     */
    wake_up_interruptible(&info->tport.delta_msr_wait);

    /*
     * Free the IRQ, if necessary
     */
    free_irq(IRQ_AMIGA_VERTB, info);

    if (info->xmit.buf) {
        free_page((unsigned long) info->xmit.buf);
        info->xmit.buf = NULL;
    }

    info->IER = 0;
    custom.intena = IF_RBF | IF_TBE;
    mb();

    /* disable break condition */
    custom.adkcon = AC_UARTBRK;
    mb();

    if (tty->termios.c_cflag & HUPCL)
        info->MCR &= ~(SER_DTR|SER_RTS);
    rtsdtr_ctrl(info->MCR);

    set_bit(TTY_IO_ERROR, &tty->flags);

    info->tport.flags &= ~ASYNC_INITIALIZED;
    local_irq_restore(flags);
}


/*
 * This routine is called to set the UART divisor registers to match
 * the specified baud rate for a serial port.
 */
static void change_speed(struct tty_struct *tty, struct serial_state *info,
             struct ktermios *old_termios)
{
    struct tty_port *port = &info->tport;
    int quot = 0, baud_base, baud;
    unsigned cflag, cval = 0;
    int bits;
    unsigned long   flags;

    cflag = tty->termios.c_cflag;

    /* Byte size is always 8 bits plus parity bit if requested */

    cval = 3; bits = 10;
    if (cflag & CSTOPB) {
        cval |= 0x04;
        bits++;
    }
    if (cflag & PARENB) {
        cval |= UART_LCR_PARITY;
        bits++;
    }
    if (!(cflag & PARODD))
        cval |= UART_LCR_EPAR;
#ifdef CMSPAR
    if (cflag & CMSPAR)
        cval |= UART_LCR_SPAR;
#endif

    /* Determine divisor based on baud rate */
    baud = tty_get_baud_rate(tty);
    if (!baud)
        baud = 9600;    /* B0 transition handled in rs_set_termios */
    baud_base = info->baud_base;
    if (baud == 38400 && (port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
        quot = info->custom_divisor;
    else {
        if (baud == 134)
            /* Special case since 134 is really 134.5 */
            quot = (2*baud_base / 269);
        else if (baud)
            quot = baud_base / baud;
    }
    /* If the quotient is zero refuse the change */
    if (!quot && old_termios) {
        /* FIXME: Will need updating for new tty in the end */
        tty->termios.c_cflag &= ~CBAUD;
        tty->termios.c_cflag |= (old_termios->c_cflag & CBAUD);
        baud = tty_get_baud_rate(tty);
        if (!baud)
            baud = 9600;
        if (baud == 38400 &&
            (port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
            quot = info->custom_divisor;
        else {
            if (baud == 134)
                /* Special case since 134 is really 134.5 */
                quot = (2*baud_base / 269);
            else if (baud)
                quot = baud_base / baud;
        }
    }
    /* As a last resort, if the quotient is zero, default to 9600 bps */
    if (!quot)
        quot = baud_base / 9600;
    info->quot = quot;
    info->timeout = ((info->xmit_fifo_size*HZ*bits*quot) / baud_base);
    info->timeout += HZ/50;     /* Add .02 seconds of slop */

    /* CTS flow control flag and modem status interrupts */
    info->IER &= ~UART_IER_MSI;
    if (port->flags & ASYNC_HARDPPS_CD)
        info->IER |= UART_IER_MSI;
    if (cflag & CRTSCTS) {
        port->flags |= ASYNC_CTS_FLOW;
        info->IER |= UART_IER_MSI;
    } else
        port->flags &= ~ASYNC_CTS_FLOW;
    if (cflag & CLOCAL)
        port->flags &= ~ASYNC_CHECK_CD;
    else {
        port->flags |= ASYNC_CHECK_CD;
        info->IER |= UART_IER_MSI;
    }
    /* TBD:
     * Does clearing IER_MSI imply that we should disable the VBL interrupt ?
     */

    /*
     * Set up parity check flag
     */

    info->read_status_mask = UART_LSR_OE | UART_LSR_DR;
    if (I_INPCK(tty))
        info->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
    if (I_BRKINT(tty) || I_PARMRK(tty))
        info->read_status_mask |= UART_LSR_BI;

    /*
     * Characters to ignore
     */
    info->ignore_status_mask = 0;
    if (I_IGNPAR(tty))
        info->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
    if (I_IGNBRK(tty)) {
        info->ignore_status_mask |= UART_LSR_BI;
        /*
         * If we're ignore parity and break indicators, ignore 
         * overruns too.  (For real raw support).
         */
        if (I_IGNPAR(tty))
            info->ignore_status_mask |= UART_LSR_OE;
    }
    /*
     * !!! ignore all characters if CREAD is not set
     */
    if ((cflag & CREAD) == 0)
        info->ignore_status_mask |= UART_LSR_DR;
    local_irq_save(flags);

    {
      short serper;

    /* Set up the baud rate */
      serper = quot - 1;

    /* Enable or disable parity bit */

    if(cval & UART_LCR_PARITY)
      serper |= (SERPER_PARENB);

    custom.serper = serper;
    mb();
    }

    local_irq_restore(flags);
}

static int rs_put_char(struct tty_struct *tty, unsigned char ch)
{
    struct serial_state *info;
    unsigned long flags;

    info = tty->driver_data;

    if (serial_paranoia_check(info, tty->name, "rs_put_char"))
        return 0;

    if (!info->xmit.buf)
        return 0;

    local_irq_save(flags);
    if (CIRC_SPACE(info->xmit.head,
               info->xmit.tail,
               SERIAL_XMIT_SIZE) == 0) {
        local_irq_restore(flags);
        return 0;
    }

    info->xmit.buf[info->xmit.head++] = ch;
    info->xmit.head &= SERIAL_XMIT_SIZE-1;
    local_irq_restore(flags);
    return 1;
}

static void rs_flush_chars(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_flush_chars"))
        return;

    if (info->xmit.head == info->xmit.tail
        || tty->stopped
        || tty->hw_stopped
        || !info->xmit.buf)
        return;

    local_irq_save(flags);
    info->IER |= UART_IER_THRI;
    custom.intena = IF_SETCLR | IF_TBE;
    mb();
    /* set a pending Tx Interrupt, transmitter should restart now */
    custom.intreq = IF_SETCLR | IF_TBE;
    mb();
    local_irq_restore(flags);
}

static int rs_write(struct tty_struct * tty, const unsigned char *buf, int count)
{
    int c, ret = 0;
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_write"))
        return 0;

    if (!info->xmit.buf)
        return 0;

    local_irq_save(flags);
    while (1) {
        c = CIRC_SPACE_TO_END(info->xmit.head,
                      info->xmit.tail,
                      SERIAL_XMIT_SIZE);
        if (count < c)
            c = count;
        if (c <= 0) {
            break;
        }
        memcpy(info->xmit.buf + info->xmit.head, buf, c);
        info->xmit.head = ((info->xmit.head + c) &
                   (SERIAL_XMIT_SIZE-1));
        buf += c;
        count -= c;
        ret += c;
    }
    local_irq_restore(flags);

    if (info->xmit.head != info->xmit.tail
        && !tty->stopped
        && !tty->hw_stopped
        && !(info->IER & UART_IER_THRI)) {
        info->IER |= UART_IER_THRI;
        local_irq_disable();
        custom.intena = IF_SETCLR | IF_TBE;
        mb();
        /* set a pending Tx Interrupt, transmitter should restart now */
        custom.intreq = IF_SETCLR | IF_TBE;
        mb();
        local_irq_restore(flags);
    }
    return ret;
}

static int rs_write_room(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    if (serial_paranoia_check(info, tty->name, "rs_write_room"))
        return 0;
    return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static int rs_chars_in_buffer(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    if (serial_paranoia_check(info, tty->name, "rs_chars_in_buffer"))
        return 0;
    return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static void rs_flush_buffer(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_flush_buffer"))
        return;
    local_irq_save(flags);
    info->xmit.head = info->xmit.tail = 0;
    local_irq_restore(flags);
    tty_wakeup(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void rs_send_xchar(struct tty_struct *tty, char ch)
{
    struct serial_state *info = tty->driver_data;
        unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_send_char"))
        return;

    info->x_char = ch;
    if (ch) {
        /* Make sure transmit interrupts are on */

            /* Check this ! */
            local_irq_save(flags);
        if(!(custom.intenar & IF_TBE)) {
            custom.intena = IF_SETCLR | IF_TBE;
            mb();
            /* set a pending Tx Interrupt, transmitter should restart now */
            custom.intreq = IF_SETCLR | IF_TBE;
            mb();
        }
        local_irq_restore(flags);

        info->IER |= UART_IER_THRI;
    }
}

/*
 * ------------------------------------------------------------
 * rs_throttle()
 * 
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void rs_throttle(struct tty_struct * tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;
#ifdef SERIAL_DEBUG_THROTTLE
    char    buf[64];

    printk("throttle %s: %d....\n", tty_name(tty, buf),
           tty->ldisc.chars_in_buffer(tty));
#endif

    if (serial_paranoia_check(info, tty->name, "rs_throttle"))
        return;

    if (I_IXOFF(tty))
        rs_send_xchar(tty, STOP_CHAR(tty));

    if (tty->termios.c_cflag & CRTSCTS)
        info->MCR &= ~SER_RTS;

    local_irq_save(flags);
    rtsdtr_ctrl(info->MCR);
    local_irq_restore(flags);
}

static void rs_unthrottle(struct tty_struct * tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;
#ifdef SERIAL_DEBUG_THROTTLE
    char    buf[64];

    printk("unthrottle %s: %d....\n", tty_name(tty, buf),
           tty->ldisc.chars_in_buffer(tty));
#endif

    if (serial_paranoia_check(info, tty->name, "rs_unthrottle"))
        return;

    if (I_IXOFF(tty)) {
        if (info->x_char)
            info->x_char = 0;
        else
            rs_send_xchar(tty, START_CHAR(tty));
    }
    if (tty->termios.c_cflag & CRTSCTS)
        info->MCR |= SER_RTS;
    local_irq_save(flags);
    rtsdtr_ctrl(info->MCR);
    local_irq_restore(flags);
}

/*
 * ------------------------------------------------------------
 * rs_ioctl() and friends
 * ------------------------------------------------------------
 */

static int get_serial_info(struct tty_struct *tty, struct serial_state *state,
               struct serial_struct __user * retinfo)
{
    struct serial_struct tmp;
   
    if (!retinfo)
        return -EFAULT;
    memset(&tmp, 0, sizeof(tmp));
    tty_lock(tty);
    tmp.line = tty->index;
    tmp.port = state->port;
    tmp.flags = state->tport.flags;
    tmp.xmit_fifo_size = state->xmit_fifo_size;
    tmp.baud_base = state->baud_base;
    tmp.close_delay = state->tport.close_delay;
    tmp.closing_wait = state->tport.closing_wait;
    tmp.custom_divisor = state->custom_divisor;
    tty_unlock(tty);
    if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
        return -EFAULT;
    return 0;
}

static int set_serial_info(struct tty_struct *tty, struct serial_state *state,
               struct serial_struct __user * new_info)
{
    struct tty_port *port = &state->tport;
    struct serial_struct new_serial;
    bool change_spd;
    int             retval = 0;

    if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
        return -EFAULT;

    tty_lock(tty);
    change_spd = ((new_serial.flags ^ port->flags) & ASYNC_SPD_MASK) ||
        new_serial.custom_divisor != state->custom_divisor;
    if (new_serial.irq || new_serial.port != state->port ||
            new_serial.xmit_fifo_size != state->xmit_fifo_size) {
        tty_unlock(tty);
        return -EINVAL;
    }
  
    if (!serial_isroot()) {
        if ((new_serial.baud_base != state->baud_base) ||
            (new_serial.close_delay != port->close_delay) ||
            (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
            ((new_serial.flags & ~ASYNC_USR_MASK) !=
             (port->flags & ~ASYNC_USR_MASK))) {
            tty_unlock(tty);
            return -EPERM;
        }
        port->flags = ((port->flags & ~ASYNC_USR_MASK) |
                   (new_serial.flags & ASYNC_USR_MASK));
        state->custom_divisor = new_serial.custom_divisor;
        goto check_and_exit;
    }

    if (new_serial.baud_base < 9600) {
        tty_unlock(tty);
        return -EINVAL;
    }

    /*
     * OK, past this point, all the error checking has been done.
     * At this point, we start making changes.....
     */

    state->baud_base = new_serial.baud_base;
    port->flags = ((port->flags & ~ASYNC_FLAGS) |
            (new_serial.flags & ASYNC_FLAGS));
    state->custom_divisor = new_serial.custom_divisor;
    port->close_delay = new_serial.close_delay * HZ/100;
    port->closing_wait = new_serial.closing_wait * HZ/100;
    tty->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

check_and_exit:
    if (port->flags & ASYNC_INITIALIZED) {
        if (change_spd) {
            if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
                tty->alt_speed = 57600;
            if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
                tty->alt_speed = 115200;
            if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
                tty->alt_speed = 230400;
            if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
                tty->alt_speed = 460800;
            change_speed(tty, state, NULL);
        }
    } else
        retval = startup(tty, state);
    tty_unlock(tty);
    return retval;
}


/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *      is emptied.  On bus types like RS485, the transmitter must
 *      release the bus after transmitting. This must be done when
 *      the transmit shift register is empty, not be done when the
 *      transmit holding register is empty.  This functionality
 *      allows an RS485 driver to be written in user space. 
 */
static int get_lsr_info(struct serial_state *info, unsigned int __user *value)
{
    unsigned char status;
    unsigned int result;
    unsigned long flags;

    local_irq_save(flags);
    status = custom.serdatr;
    mb();
    local_irq_restore(flags);
    result = ((status & SDR_TSRE) ? TIOCSER_TEMT : 0);
    if (copy_to_user(value, &result, sizeof(int)))
        return -EFAULT;
    return 0;
}


static int rs_tiocmget(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;
    unsigned char control, status;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_ioctl"))
        return -ENODEV;
    if (tty->flags & (1 << TTY_IO_ERROR))
        return -EIO;

    control = info->MCR;
    local_irq_save(flags);
    status = ciab.pra;
    local_irq_restore(flags);
    return    ((control & SER_RTS) ? TIOCM_RTS : 0)
        | ((control & SER_DTR) ? TIOCM_DTR : 0)
        | (!(status  & SER_DCD) ? TIOCM_CAR : 0)
        | (!(status  & SER_DSR) ? TIOCM_DSR : 0)
        | (!(status  & SER_CTS) ? TIOCM_CTS : 0);
}

static int rs_tiocmset(struct tty_struct *tty, unsigned int set,
                        unsigned int clear)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_ioctl"))
        return -ENODEV;
    if (tty->flags & (1 << TTY_IO_ERROR))
        return -EIO;

    local_irq_save(flags);
    if (set & TIOCM_RTS)
        info->MCR |= SER_RTS;
    if (set & TIOCM_DTR)
        info->MCR |= SER_DTR;
    if (clear & TIOCM_RTS)
        info->MCR &= ~SER_RTS;
    if (clear & TIOCM_DTR)
        info->MCR &= ~SER_DTR;
    rtsdtr_ctrl(info->MCR);
    local_irq_restore(flags);
    return 0;
}

/*
 * rs_break() --- routine which turns the break handling on or off
 */
static int rs_break(struct tty_struct *tty, int break_state)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_break"))
        return -EINVAL;

    local_irq_save(flags);
    if (break_state == -1)
      custom.adkcon = AC_SETCLR | AC_UARTBRK;
    else
      custom.adkcon = AC_UARTBRK;
    mb();
    local_irq_restore(flags);
    return 0;
}

/*
 * 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 rs_get_icount(struct tty_struct *tty,
                struct serial_icounter_struct *icount)
{
    struct serial_state *info = tty->driver_data;
    struct async_icount cnow;
    unsigned long flags;

    local_irq_save(flags);
    cnow = info->icount;
    local_irq_restore(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;
}

static int rs_ioctl(struct tty_struct *tty,
            unsigned int cmd, unsigned long arg)
{
    struct serial_state *info = tty->driver_data;
    struct async_icount cprev, cnow;    /* kernel counter temps */
    void __user *argp = (void __user *)arg;
    unsigned long flags;

    if (serial_paranoia_check(info, tty->name, "rs_ioctl"))
        return -ENODEV;

    if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
        (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
        (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
        if (tty->flags & (1 << TTY_IO_ERROR))
            return -EIO;
    }

    switch (cmd) {
        case TIOCGSERIAL:
            return get_serial_info(tty, info, argp);
        case TIOCSSERIAL:
            return set_serial_info(tty, info, argp);
        case TIOCSERCONFIG:
            return 0;

        case TIOCSERGETLSR: /* Get line status register */
            return get_lsr_info(info, argp);

        case TIOCSERGSTRUCT:
            if (copy_to_user(argp,
                     info, sizeof(struct serial_state)))
                return -EFAULT;
            return 0;

        /*
         * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
         * - mask passed in arg for lines of interest
         *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
         * Caller should use TIOCGICOUNT to see which one it was
         */
        case TIOCMIWAIT:
            local_irq_save(flags);
            /* note the counters on entry */
            cprev = info->icount;
            local_irq_restore(flags);
            while (1) {
                interruptible_sleep_on(&info->tport.delta_msr_wait);
                /* see if a signal did it */
                if (signal_pending(current))
                    return -ERESTARTSYS;
                local_irq_save(flags);
                cnow = info->icount; /* atomic copy */
                local_irq_restore(flags);
                if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr && 
                    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
                    return -EIO; /* no change => error */
                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)) ) {
                    return 0;
                }
                cprev = cnow;
            }
            /* NOTREACHED */

        case TIOCSERGWILD:
        case TIOCSERSWILD:
            /* "setserial -W" is called in Debian boot */
            printk ("TIOCSER?WILD ioctl obsolete, ignored.\n");
            return 0;

        default:
            return -ENOIOCTLCMD;
        }
    return 0;
}

static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
    struct serial_state *info = tty->driver_data;
    unsigned long flags;
    unsigned int cflag = tty->termios.c_cflag;

    change_speed(tty, info, old_termios);

    /* Handle transition to B0 status */
    if ((old_termios->c_cflag & CBAUD) &&
        !(cflag & CBAUD)) {
        info->MCR &= ~(SER_DTR|SER_RTS);
        local_irq_save(flags);
        rtsdtr_ctrl(info->MCR);
        local_irq_restore(flags);
    }

    /* Handle transition away from B0 status */
    if (!(old_termios->c_cflag & CBAUD) &&
        (cflag & CBAUD)) {
        info->MCR |= SER_DTR;
        if (!(tty->termios.c_cflag & CRTSCTS) || 
            !test_bit(TTY_THROTTLED, &tty->flags)) {
            info->MCR |= SER_RTS;
        }
        local_irq_save(flags);
        rtsdtr_ctrl(info->MCR);
        local_irq_restore(flags);
    }

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

#if 0
    /*
     * No need to wake up processes in open wait, since they
     * sample the CLOCAL flag once, and don't recheck it.
     * XXX  It's not clear whether the current behavior is correct
     * or not.  Hence, this may change.....
     */
    if (!(old_termios->c_cflag & CLOCAL) &&
        (tty->termios.c_cflag & CLOCAL))
        wake_up_interruptible(&info->open_wait);
#endif
}

/*
 * ------------------------------------------------------------
 * rs_close()
 * 
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we unlink its
 * async structure from the interrupt chain if necessary, and we free
 * that IRQ if nothing is left in the chain.
 * ------------------------------------------------------------
 */
static void rs_close(struct tty_struct *tty, struct file * filp)
{
    struct serial_state *state = tty->driver_data;
    struct tty_port *port = &state->tport;

    if (serial_paranoia_check(state, tty->name, "rs_close"))
        return;

    if (tty_port_close_start(port, tty, filp) == 0)
        return;

    /*
     * At this point we stop accepting input.  To do this, we
     * disable the receive line status interrupts, and tell the
     * interrupt driver to stop checking the data ready bit in the
     * line status register.
     */
    state->read_status_mask &= ~UART_LSR_DR;
    if (port->flags & ASYNC_INITIALIZED) {
            /* disable receive interrupts */
            custom.intena = IF_RBF;
        mb();
        /* clear any pending receive interrupt */
        custom.intreq = IF_RBF;
        mb();

        /*
         * Before we drop DTR, make sure the UART transmitter
         * has completely drained; this is especially
         * important if there is a transmit FIFO!
         */
        rs_wait_until_sent(tty, state->timeout);
    }
    shutdown(tty, state);
    rs_flush_buffer(tty);
        
    tty_ldisc_flush(tty);
    port->tty = NULL;

    tty_port_close_end(port, tty);
}

/*
 * rs_wait_until_sent() --- wait until the transmitter is empty
 */
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
    struct serial_state *info = tty->driver_data;
    unsigned long orig_jiffies, char_time;
    int lsr;

    if (serial_paranoia_check(info, tty->name, "rs_wait_until_sent"))
        return;

    if (info->xmit_fifo_size == 0)
        return; /* Just in case.... */

    orig_jiffies = jiffies;

    /*
     * Set the check interval to be 1/5 of the estimated time to
     * send a single character, and make it at least 1.  The check
     * interval should also be less than the timeout.
     * 
     * Note: we have to use pretty tight timings here to satisfy
     * the NIST-PCTS.
     */
    char_time = (info->timeout - HZ/50) / info->xmit_fifo_size;
    char_time = char_time / 5;
    if (char_time == 0)
        char_time = 1;
    if (timeout)
      char_time = min_t(unsigned long, char_time, timeout);
    /*
     * If the transmitter hasn't cleared in twice the approximate
     * amount of time to send the entire FIFO, it probably won't
     * ever clear.  This assumes the UART isn't doing flow
     * control, which is currently the case.  Hence, if it ever
     * takes longer than info->timeout, this is probably due to a
     * UART bug of some kind.  So, we clamp the timeout parameter at
     * 2*info->timeout.
     */
    if (!timeout || timeout > 2*info->timeout)
        timeout = 2*info->timeout;
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
    printk("In rs_wait_until_sent(%d) check=%lu...", timeout, char_time);
    printk("jiff=%lu...", jiffies);
#endif
    while(!((lsr = custom.serdatr) & SDR_TSRE)) {
#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
        printk("serdatr = %d (jiff=%lu)...", lsr, jiffies);
#endif
        msleep_interruptible(jiffies_to_msecs(char_time));
        if (signal_pending(current))
            break;
        if (timeout && time_after(jiffies, orig_jiffies + timeout))
            break;
    }
    __set_current_state(TASK_RUNNING);

#ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
    printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
#endif
}

/*
 * rs_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
static void rs_hangup(struct tty_struct *tty)
{
    struct serial_state *info = tty->driver_data;

    if (serial_paranoia_check(info, tty->name, "rs_hangup"))
        return;

    rs_flush_buffer(tty);
    shutdown(tty, info);
    info->tport.count = 0;
    info->tport.flags &= ~ASYNC_NORMAL_ACTIVE;
    info->tport.tty = NULL;
    wake_up_interruptible(&info->tport.open_wait);
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its async structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
static int rs_open(struct tty_struct *tty, struct file * filp)
{
    struct serial_state *info = rs_table + tty->index;
    struct tty_port *port = &info->tport;
    int retval;

    port->count++;
    port->tty = tty;
    tty->driver_data = info;
    tty->port = port;
    if (serial_paranoia_check(info, tty->name, "rs_open"))
        return -ENODEV;

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

    retval = startup(tty, info);
    if (retval) {
        return retval;
    }

    return tty_port_block_til_ready(port, tty, filp);
}

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

static inline void line_info(struct seq_file *m, int line,
        struct serial_state *state)
{
    char    stat_buf[30], control, status;
    unsigned long flags;

    seq_printf(m, "%d: uart:amiga_builtin", line);

    local_irq_save(flags);
    status = ciab.pra;
    control = (state->tport.flags & ASYNC_INITIALIZED) ? state->MCR : status;
    local_irq_restore(flags);

    stat_buf[0] = 0;
    stat_buf[1] = 0;
    if(!(control & SER_RTS))
        strcat(stat_buf, "|RTS");
    if(!(status & SER_CTS))
        strcat(stat_buf, "|CTS");
    if(!(control & SER_DTR))
        strcat(stat_buf, "|DTR");
    if(!(status & SER_DSR))
        strcat(stat_buf, "|DSR");
    if(!(status & SER_DCD))
        strcat(stat_buf, "|CD");

    if (state->quot)
        seq_printf(m, " baud:%d", state->baud_base / state->quot);

    seq_printf(m, " tx:%d rx:%d", state->icount.tx, state->icount.rx);

    if (state->icount.frame)
        seq_printf(m, " fe:%d", state->icount.frame);

    if (state->icount.parity)
        seq_printf(m, " pe:%d", state->icount.parity);

    if (state->icount.brk)
        seq_printf(m, " brk:%d", state->icount.brk);

    if (state->icount.overrun)
        seq_printf(m, " oe:%d", state->icount.overrun);

    /*
     * Last thing is the RS-232 status lines
     */
    seq_printf(m, " %s\n", stat_buf+1);
}

static int rs_proc_show(struct seq_file *m, void *v)
{
    seq_printf(m, "serinfo:1.0 driver:%s\n", serial_version);
    line_info(m, 0, &rs_table[0]);
    return 0;
}

static int rs_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, rs_proc_show, NULL);
}

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

/*
 * ---------------------------------------------------------------------
 * rs_init() and friends
 *
 * rs_init() is called at boot-time to initialize the serial driver.
 * ---------------------------------------------------------------------
 */

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static void show_serial_version(void)
{
    printk(KERN_INFO "%s version %s\n", serial_name, serial_version);
}


static const struct tty_operations serial_ops = {
    .open = rs_open,
    .close = rs_close,
    .write = rs_write,
    .put_char = rs_put_char,
    .flush_chars = rs_flush_chars,
    .write_room = rs_write_room,
    .chars_in_buffer = rs_chars_in_buffer,
    .flush_buffer = rs_flush_buffer,
    .ioctl = rs_ioctl,
    .throttle = rs_throttle,
    .unthrottle = rs_unthrottle,
    .set_termios = rs_set_termios,
    .stop = rs_stop,
    .start = rs_start,
    .hangup = rs_hangup,
    .break_ctl = rs_break,
    .send_xchar = rs_send_xchar,
    .wait_until_sent = rs_wait_until_sent,
    .tiocmget = rs_tiocmget,
    .tiocmset = rs_tiocmset,
    .get_icount = rs_get_icount,
    .proc_fops = &rs_proc_fops,
};

static int amiga_carrier_raised(struct tty_port *port)
{
    return !(ciab.pra & SER_DCD);
}

static void amiga_dtr_rts(struct tty_port *port, int raise)
{
    struct serial_state *info = container_of(port, struct serial_state,
            tport);
    unsigned long flags;

    if (raise)
        info->MCR |= SER_DTR|SER_RTS;
    else
        info->MCR &= ~(SER_DTR|SER_RTS);

    local_irq_save(flags);
    rtsdtr_ctrl(info->MCR);
    local_irq_restore(flags);
}

static const struct tty_port_operations amiga_port_ops = {
    .carrier_raised = amiga_carrier_raised,
    .dtr_rts = amiga_dtr_rts,
};

/*
 * The serial driver boot-time initialization code!
 */
static int __init amiga_serial_probe(struct platform_device *pdev)
{
    unsigned long flags;
    struct serial_state * state;
    int error;

    serial_driver = alloc_tty_driver(NR_PORTS);
    if (!serial_driver)
        return -ENOMEM;

    show_serial_version();

    /* Initialize the tty_driver structure */

    serial_driver->driver_name = "amiserial";
    serial_driver->name = "ttyS";
    serial_driver->major = TTY_MAJOR;
    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->flags = TTY_DRIVER_REAL_RAW;
    tty_set_operations(serial_driver, &serial_ops);

    state = rs_table;
    state->port = (int)&custom.serdatr; /* Just to give it a value */
    state->custom_divisor = 0;
    state->icount.cts = state->icount.dsr = 
      state->icount.rng = state->icount.dcd = 0;
    state->icount.rx = state->icount.tx = 0;
    state->icount.frame = state->icount.parity = 0;
    state->icount.overrun = state->icount.brk = 0;
    tty_port_init(&state->tport);
    state->tport.ops = &amiga_port_ops;
    tty_port_link_device(&state->tport, serial_driver, 0);

    error = tty_register_driver(serial_driver);
    if (error)
        goto fail_put_tty_driver;

    printk(KERN_INFO "ttyS0 is the amiga builtin serial port\n");

    /* Hardware set up */

    state->baud_base = amiga_colorclock;
    state->xmit_fifo_size = 1;

    /* set ISRs, and then disable the rx interrupts */
    error = request_irq(IRQ_AMIGA_TBE, ser_tx_int, 0, "serial TX", state);
    if (error)
        goto fail_unregister;

    error = request_irq(IRQ_AMIGA_RBF, ser_rx_int, 0,
                "serial RX", state);
    if (error)
        goto fail_free_irq;

    local_irq_save(flags);

    /* turn off Rx and Tx interrupts */
    custom.intena = IF_RBF | IF_TBE;
    mb();

    /* clear any pending interrupt */
    custom.intreq = IF_RBF | IF_TBE;
    mb();

    local_irq_restore(flags);

    /*
     * set the appropriate directions for the modem control flags,
     * and clear RTS and DTR
     */
    ciab.ddra |= (SER_DTR | SER_RTS);   /* outputs */
    ciab.ddra &= ~(SER_DCD | SER_CTS | SER_DSR);  /* inputs */

    platform_set_drvdata(pdev, state);

    return 0;

fail_free_irq:
    free_irq(IRQ_AMIGA_TBE, state);
fail_unregister:
    tty_unregister_driver(serial_driver);
fail_put_tty_driver:
    put_tty_driver(serial_driver);
    return error;
}

static int __exit amiga_serial_remove(struct platform_device *pdev)
{
    int error;
    struct serial_state *state = platform_get_drvdata(pdev);

    /* printk("Unloading %s: version %s\n", serial_name, serial_version); */
    if ((error = tty_unregister_driver(serial_driver)))
        printk("SERIAL: failed to unregister serial driver (%d)\n",
               error);
    put_tty_driver(serial_driver);

    free_irq(IRQ_AMIGA_TBE, state);
    free_irq(IRQ_AMIGA_RBF, state);

    platform_set_drvdata(pdev, NULL);

    return error;
}

static struct platform_driver amiga_serial_driver = {
    .remove = __exit_p(amiga_serial_remove),
    .driver   = {
        .name   = "amiga-serial",
        .owner  = THIS_MODULE,
    },
};

static int __init amiga_serial_init(void)
{
    return platform_driver_probe(&amiga_serial_driver, amiga_serial_probe);
}

module_init(amiga_serial_init);

static void __exit amiga_serial_exit(void)
{
    platform_driver_unregister(&amiga_serial_driver);
}

module_exit(amiga_serial_exit);


#if defined(CONFIG_SERIAL_CONSOLE) && !defined(MODULE)

/*
 * ------------------------------------------------------------
 * Serial console driver
 * ------------------------------------------------------------
 */

static void amiga_serial_putc(char c)
{
    custom.serdat = (unsigned char)c | 0x100;
    while (!(custom.serdatr & 0x2000))
        barrier();
}

/*
 *  Print a string to the serial port trying not to disturb
 *  any possible real use of the port...
 *
 *  The console must be locked when we get here.
 */
static void serial_console_write(struct console *co, const char *s,
                unsigned count)
{
    unsigned short intena = custom.intenar;

    custom.intena = IF_TBE;

    while (count--) {
        if (*s == '\n')
            amiga_serial_putc('\r');
        amiga_serial_putc(*s++);
    }

    custom.intena = IF_SETCLR | (intena & IF_TBE);
}

static struct tty_driver *serial_console_device(struct console *c, int *index)
{
    *index = 0;
    return serial_driver;
}

static struct console sercons = {
    .name =     "ttyS",
    .write =    serial_console_write,
    .device =   serial_console_device,
    .flags =    CON_PRINTBUFFER,
    .index =    -1,
};

/*
 *  Register console.
 */
static int __init amiserial_console_init(void)
{
    register_console(&sercons);
    return 0;
}
console_initcall(amiserial_console_init);

#endif /* CONFIG_SERIAL_CONSOLE && !MODULE */

MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:amiga-serial");