Merge branch 'elevator-switch' of git://brick.kernel.dk/data/git/linux-2.6-block

[linux-2.6] / drivers / char / amiserial.c

/*
 *  linux/drivers/char/amiserial.c
 *
 * 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/config.h>
#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 */

#define SERIAL_INLINE
  
#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->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/serialP.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/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/slab.h>
#include <linux/init.h>
#include <linux/bitops.h>

#include <asm/setup.h>

#include <asm/system.h>

#include <asm/irq.h>

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

#ifdef SERIAL_INLINE
#define _INLINE_ inline
#endif

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 struct async_struct *IRQ_ports;

static unsigned char current_ctl_bits;

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


static struct serial_state rs_table[1];

#define NR_PORTS        (sizeof(rs_table)/sizeof(struct serial_state))

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the copy_from_user blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char *tmp_buf;
static DECLARE_MUTEX(tmp_buf_sem);

#include <asm/uaccess.h>

#define serial_isroot() (capable(CAP_SYS_ADMIN))


static inline int serial_paranoia_check(struct async_struct *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 async_struct *info = (struct async_struct *)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 async_struct *info = (struct async_struct *)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 (tytso@mit.edu), 7-Mar-93
 * -----------------------------------------------------------------------
 */

/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static _INLINE_ void rs_sched_event(struct async_struct *info,
                                  int event)
{
        info->event |= 1 << event;
        tasklet_schedule(&info->tlet);
}

static _INLINE_ void receive_chars(struct async_struct *info)
{
        int status;
        int serdatr;
        struct tty_struct *tty = info->tty;
        unsigned char ch;
        struct  async_icount *icount;

        icount = &info->state->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;
        if (tty->flip.count >= TTY_FLIPBUF_SIZE)
          goto ignore_char;
        *tty->flip.char_buf_ptr = ch;
        icount->rx++;

#ifdef SERIAL_DEBUG_INTR
        printk("DR%02x:%02x...", ch, status);
#endif
        *tty->flip.flag_buf_ptr = 0;

        /*
         * 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 ignore_char;

          status &= info->read_status_mask;

          if (status & (UART_LSR_BI)) {
#ifdef SERIAL_DEBUG_INTR
            printk("handling break....");
#endif
            *tty->flip.flag_buf_ptr = TTY_BREAK;
            if (info->flags & ASYNC_SAK)
              do_SAK(tty);
          } else if (status & UART_LSR_PE)
            *tty->flip.flag_buf_ptr = TTY_PARITY;
          else if (status & UART_LSR_FE)
            *tty->flip.flag_buf_ptr = TTY_FRAME;
          if (status & UART_LSR_OE) {
            /*
             * Overrun is special, since it's
             * reported immediately, and doesn't
             * affect the current character
             */
            if (tty->flip.count < TTY_FLIPBUF_SIZE) {
              tty->flip.count++;
              tty->flip.flag_buf_ptr++;
              tty->flip.char_buf_ptr++;
              *tty->flip.flag_buf_ptr = TTY_OVERRUN;
            }
          }
        }
        tty->flip.flag_buf_ptr++;
        tty->flip.char_buf_ptr++;
        tty->flip.count++;
 ignore_char:

        tty_flip_buffer_push(tty);
}

static _INLINE_ void transmit_chars(struct async_struct *info)
{
        custom.intreq = IF_TBE;
        mb();
        if (info->x_char) {
                custom.serdat = info->x_char | 0x100;
                mb();
                info->state->icount.tx++;
                info->x_char = 0;
                return;
        }
        if (info->xmit.head == info->xmit.tail
            || info->tty->stopped
            || info->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->state->icount.tx++;

        if (CIRC_CNT(info->xmit.head,
                     info->xmit.tail,
                     SERIAL_XMIT_SIZE) < WAKEUP_CHARS)
                rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

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

        if ((info->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(&info->open_wait);
                else {
#ifdef SERIAL_DEBUG_OPEN
                        printk("doing serial hangup...");
#endif
                        if (info->tty)
                                tty_hangup(info->tty);
                }
        }
        if (info->flags & ASYNC_CTS_FLOW) {
                if (info->tty->hw_stopped) {
                        if (!(status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
                                printk("CTS tx start...");
#endif
                                info->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();
                                rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
                                return;
                        }
                } else {
                        if ((status & SER_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
                                printk("CTS tx stop...");
#endif
                                info->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, struct pt_regs *regs)
{
        /* vbl is just a periodic interrupt we tie into to update modem status */
        struct async_struct * info = IRQ_ports;
        /*
         * 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 pt_regs * regs)
{
        struct async_struct * info;

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

        info = IRQ_ports;
        if (!info || !info->tty)
                return IRQ_NONE;

        receive_chars(info);
        info->last_active = jiffies;
#ifdef SERIAL_DEBUG_INTR
        printk("end.\n");
#endif
        return IRQ_HANDLED;
}

static irqreturn_t ser_tx_int(int irq, void *dev_id, struct pt_regs * regs)
{
        struct async_struct * info;

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

          info = IRQ_ports;
          if (!info || !info->tty)
                return IRQ_NONE;

          transmit_chars(info);
          info->last_active = jiffies;
#ifdef SERIAL_DEBUG_INTR
          printk("end.\n");
#endif
        }
        return IRQ_HANDLED;
}

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

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * rs_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using rs_sched_event(), and they get done here.
 */

static void do_softint(unsigned long private_)
{
        struct async_struct     *info = (struct async_struct *) private_;
        struct tty_struct       *tty;

        tty = info->tty;
        if (!tty)
                return;

        if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &info->event)) {
                tty_wakeup(tty);
                wake_up_interruptible(&tty->write_wait);
        }
}

/*
 * ---------------------------------------------------------------
 * 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 async_struct * info)
{
        unsigned long flags;
        int     retval=0;
        unsigned long page;

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

        local_irq_save(flags);

        if (info->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()) {
            if (info->tty)
              set_bit(TTY_IO_ERROR,
                      &info->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);

        IRQ_ports = info;

        info->MCR = 0;
        if (info->tty->termios->c_cflag & CBAUD)
          info->MCR = SER_DTR | SER_RTS;
        rtsdtr_ctrl(info->MCR);

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

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

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

        info->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 async_struct * info)
{
        unsigned long   flags;
        struct serial_state *state;

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

        state = info->state;

#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->delta_msr_wait);

        IRQ_ports = NULL;

        /*
         * 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 (!info->tty || (info->tty->termios->c_cflag & HUPCL))
                info->MCR &= ~(SER_DTR|SER_RTS);
        rtsdtr_ctrl(info->MCR);

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

        info->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 async_struct *info,
                         struct termios *old_termios)
{
        int     quot = 0, baud_base, baud;
        unsigned cflag, cval = 0;
        int     bits;
        unsigned long   flags;

        if (!info->tty || !info->tty->termios)
                return;
        cflag = info->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(info->tty);
        if (!baud)
                baud = 9600;    /* B0 transition handled in rs_set_termios */
        baud_base = info->state->baud_base;
        if (baud == 38400 &&
            ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST))
                quot = info->state->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) {
                info->tty->termios->c_cflag &= ~CBAUD;
                info->tty->termios->c_cflag |= (old_termios->c_cflag & CBAUD);
                baud = tty_get_baud_rate(info->tty);
                if (!baud)
                        baud = 9600;
                if (baud == 38400 &&
                    ((info->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST))
                        quot = info->state->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 (info->flags & ASYNC_HARDPPS_CD)
                info->IER |= UART_IER_MSI;
        if (cflag & CRTSCTS) {
                info->flags |= ASYNC_CTS_FLOW;
                info->IER |= UART_IER_MSI;
        } else
                info->flags &= ~ASYNC_CTS_FLOW;
        if (cflag & CLOCAL)
                info->flags &= ~ASYNC_CHECK_CD;
        else {
                info->flags |= ASYNC_CHECK_CD;
                info->IER |= UART_IER_MSI;
        }
        /* TBD:
         * Does clearing IER_MSI imply that we should disbale the VBL interrupt ?
         */

        /*
         * Set up parity check flag
         */
#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

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

        /*
         * Characters to ignore
         */
        info->ignore_status_mask = 0;
        if (I_IGNPAR(info->tty))
                info->ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
        if (I_IGNBRK(info->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(info->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();
        }

        info->LCR = cval;                               /* Save LCR */
        local_irq_restore(flags);
}

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

        if (!tty)
                return;

        info = tty->driver_data;

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

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

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

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

static void rs_flush_chars(struct tty_struct *tty)
{
        struct async_struct *info = (struct async_struct *)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 async_struct *info;
        unsigned long flags;

        if (!tty)
                return 0;

        info = tty->driver_data;

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

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

        local_save_flags(flags);
        local_irq_disable();
        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 async_struct *info = (struct async_struct *)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 async_struct *info = (struct async_struct *)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 async_struct *info = (struct async_struct *)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);
        wake_up_interruptible(&tty->write_wait);
        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 async_struct *info = (struct async_struct *)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 async_struct *info = (struct async_struct *)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 async_struct *info = (struct async_struct *)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 async_struct * info,
                           struct serial_struct * retinfo)
{
        struct serial_struct tmp;
        struct serial_state *state = info->state;
   
        if (!retinfo)
                return -EFAULT;
        memset(&tmp, 0, sizeof(tmp));
        tmp.type = state->type;
        tmp.line = state->line;
        tmp.port = state->port;
        tmp.irq = state->irq;
        tmp.flags = state->flags;
        tmp.xmit_fifo_size = state->xmit_fifo_size;
        tmp.baud_base = state->baud_base;
        tmp.close_delay = state->close_delay;
        tmp.closing_wait = state->closing_wait;
        tmp.custom_divisor = state->custom_divisor;
        if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
                return -EFAULT;
        return 0;
}

static int set_serial_info(struct async_struct * info,
                           struct serial_struct * new_info)
{
        struct serial_struct new_serial;
        struct serial_state old_state, *state;
        unsigned int            change_irq,change_port;
        int                     retval = 0;

        if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
                return -EFAULT;
        state = info->state;
        old_state = *state;
  
        change_irq = new_serial.irq != state->irq;
        change_port = (new_serial.port != state->port);
        if(change_irq || change_port || (new_serial.xmit_fifo_size != state->xmit_fifo_size))
          return -EINVAL;
  
        if (!serial_isroot()) {
                if ((new_serial.baud_base != state->baud_base) ||
                    (new_serial.close_delay != state->close_delay) ||
                    (new_serial.xmit_fifo_size != state->xmit_fifo_size) ||
                    ((new_serial.flags & ~ASYNC_USR_MASK) !=
                     (state->flags & ~ASYNC_USR_MASK)))
                        return -EPERM;
                state->flags = ((state->flags & ~ASYNC_USR_MASK) |
                               (new_serial.flags & ASYNC_USR_MASK));
                info->flags = ((info->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)
                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;
        state->flags = ((state->flags & ~ASYNC_FLAGS) |
                        (new_serial.flags & ASYNC_FLAGS));
        info->flags = ((state->flags & ~ASYNC_INTERNAL_FLAGS) |
                       (info->flags & ASYNC_INTERNAL_FLAGS));
        state->custom_divisor = new_serial.custom_divisor;
        state->close_delay = new_serial.close_delay * HZ/100;
        state->closing_wait = new_serial.closing_wait * HZ/100;
        info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

check_and_exit:
        if (info->flags & ASYNC_INITIALIZED) {
                if (((old_state.flags & ASYNC_SPD_MASK) !=
                     (state->flags & ASYNC_SPD_MASK)) ||
                    (old_state.custom_divisor != state->custom_divisor)) {
                        if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
                                info->tty->alt_speed = 57600;
                        if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
                                info->tty->alt_speed = 115200;
                        if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
                                info->tty->alt_speed = 230400;
                        if ((state->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
                                info->tty->alt_speed = 460800;
                        change_speed(info, NULL);
                }
        } else
                retval = startup(info);
        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 async_struct * info, unsigned int *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 file *file)
{
        struct async_struct * info = (struct async_struct *)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, struct file *file,
                       unsigned int set, unsigned int clear)
{
        struct async_struct * info = (struct async_struct *)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 void rs_break(struct tty_struct *tty, int break_state)
{
        struct async_struct * info = (struct async_struct *)tty->driver_data;
        unsigned long flags;

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

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


static int rs_ioctl(struct tty_struct *tty, struct file * file,
                    unsigned int cmd, unsigned long arg)
{
        struct async_struct * info = (struct async_struct *)tty->driver_data;
        struct async_icount cprev, cnow;        /* kernel counter temps */
        struct serial_icounter_struct icount;
        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(info,
                                               (struct serial_struct *) arg);
                case TIOCSSERIAL:
                        return set_serial_info(info,
                                               (struct serial_struct *) arg);
                case TIOCSERCONFIG:
                        return 0;

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

                case TIOCSERGSTRUCT:
                        if (copy_to_user((struct async_struct *) arg,
                                         info, sizeof(struct async_struct)))
                                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->state->icount;
                        local_irq_restore(flags);
                        while (1) {
                                interruptible_sleep_on(&info->delta_msr_wait);
                                /* see if a signal did it */
                                if (signal_pending(current))
                                        return -ERESTARTSYS;
                                local_irq_save(flags);
                                cnow = info->state->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 */

                /* 
                 * 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.
                 */
                case TIOCGICOUNT:
                        local_irq_save(flags);
                        cnow = info->state->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;

                        if (copy_to_user((void *)arg, &icount, sizeof(icount)))
                                return -EFAULT;
                        return 0;
                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 termios *old_termios)
{
        struct async_struct *info = (struct async_struct *)tty->driver_data;
        unsigned long flags;
        unsigned int cflag = tty->termios->c_cflag;

        if (   (cflag == old_termios->c_cflag)
            && (   RELEVANT_IFLAG(tty->termios->c_iflag) 
                == RELEVANT_IFLAG(old_termios->c_iflag)))
          return;

        change_speed(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 async_struct * info = (struct async_struct *)tty->driver_data;
        struct serial_state *state;
        unsigned long flags;

        if (!info || serial_paranoia_check(info, tty->name, "rs_close"))
                return;

        state = info->state;

        local_irq_save(flags);

        if (tty_hung_up_p(filp)) {
                DBG_CNT("before DEC-hung");
                local_irq_restore(flags);
                return;
        }

#ifdef SERIAL_DEBUG_OPEN
        printk("rs_close ttys%d, count = %d\n", info->line, state->count);
#endif
        if ((tty->count == 1) && (state->count != 1)) {
                /*
                 * Uh, oh.  tty->count is 1, which means that the tty
                 * structure will be freed.  state->count should always
                 * be one in these conditions.  If it's greater than
                 * one, we've got real problems, since it means the
                 * serial port won't be shutdown.
                 */
                printk("rs_close: bad serial port count; tty->count is 1, "
                       "state->count is %d\n", state->count);
                state->count = 1;
        }
        if (--state->count < 0) {
                printk("rs_close: bad serial port count for ttys%d: %d\n",
                       info->line, state->count);
                state->count = 0;
        }
        if (state->count) {
                DBG_CNT("before DEC-2");
                local_irq_restore(flags);
                return;
        }
        info->flags |= ASYNC_CLOSING;
        /*
         * Now we wait for the transmit buffer to clear; and we notify 
         * the line discipline to only process XON/XOFF characters.
         */
        tty->closing = 1;
        if (info->closing_wait != ASYNC_CLOSING_WAIT_NONE)
                tty_wait_until_sent(tty, info->closing_wait);
        /*
         * 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.
         */
        info->read_status_mask &= ~UART_LSR_DR;
        if (info->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, info->timeout);
        }
        shutdown(info);
        if (tty->driver->flush_buffer)
                tty->driver->flush_buffer(tty);
                
        tty_ldisc_flush(tty);
        tty->closing = 0;
        info->event = 0;
        info->tty = NULL;
        if (info->blocked_open) {
                if (info->close_delay) {
                        msleep_interruptible(jiffies_to_msecs(info->close_delay));
                }
                wake_up_interruptible(&info->open_wait);
        }
        info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
        wake_up_interruptible(&info->close_wait);
        local_irq_restore(flags);
}

/*
 * rs_wait_until_sent() --- wait until the transmitter is empty
 */
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
        struct async_struct * info = (struct async_struct *)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;
        }
        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 async_struct * info = (struct async_struct *)tty->driver_data;
        struct serial_state *state = info->state;

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

        state = info->state;

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

/*
 * ------------------------------------------------------------
 * rs_open() and friends
 * ------------------------------------------------------------
 */
static int block_til_ready(struct tty_struct *tty, struct file * filp,
                           struct async_struct *info)
{
#ifdef DECLARE_WAITQUEUE
        DECLARE_WAITQUEUE(wait, current);
#else
        struct wait_queue wait = { current, NULL };
#endif
        struct serial_state *state = info->state;
        int             retval;
        int             do_clocal = 0, extra_count = 0;
        unsigned long   flags;

        /*
         * If the device is in the middle of being closed, then block
         * until it's done, and then try again.
         */
        if (tty_hung_up_p(filp) ||
            (info->flags & ASYNC_CLOSING)) {
                if (info->flags & ASYNC_CLOSING)
                        interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
                return ((info->flags & ASYNC_HUP_NOTIFY) ?
                        -EAGAIN : -ERESTARTSYS);
#else
                return -EAGAIN;
#endif
        }

        /*
         * If non-blocking mode is set, or the port is not enabled,
         * then make the check up front and then exit.
         */
        if ((filp->f_flags & O_NONBLOCK) ||
            (tty->flags & (1 << TTY_IO_ERROR))) {
                info->flags |= ASYNC_NORMAL_ACTIVE;
                return 0;
        }

        if (tty->termios->c_cflag & CLOCAL)
                do_clocal = 1;

        /*
         * Block waiting for the carrier detect and the line to become
         * free (i.e., not in use by the callout).  While we are in
         * this loop, state->count is dropped by one, so that
         * rs_close() knows when to free things.  We restore it upon
         * exit, either normal or abnormal.
         */
        retval = 0;
        add_wait_queue(&info->open_wait, &wait);
#ifdef SERIAL_DEBUG_OPEN
        printk("block_til_ready before block: ttys%d, count = %d\n",
               state->line, state->count);
#endif
        local_irq_save(flags);
        if (!tty_hung_up_p(filp)) {
                extra_count = 1;
                state->count--;
        }
        local_irq_restore(flags);
        info->blocked_open++;
        while (1) {
                local_irq_save(flags);
                if (tty->termios->c_cflag & CBAUD)
                        rtsdtr_ctrl(SER_DTR|SER_RTS);
                local_irq_restore(flags);
                set_current_state(TASK_INTERRUPTIBLE);
                if (tty_hung_up_p(filp) ||
                    !(info->flags & ASYNC_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
                        if (info->flags & ASYNC_HUP_NOTIFY)
                                retval = -EAGAIN;
                        else
                                retval = -ERESTARTSYS;
#else
                        retval = -EAGAIN;
#endif
                        break;
                }
                if (!(info->flags & ASYNC_CLOSING) &&
                    (do_clocal || (!(ciab.pra & SER_DCD)) ))
                        break;
                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        break;
                }
#ifdef SERIAL_DEBUG_OPEN
                printk("block_til_ready blocking: ttys%d, count = %d\n",
                       info->line, state->count);
#endif
                schedule();
        }
        current->state = TASK_RUNNING;
        remove_wait_queue(&info->open_wait, &wait);
        if (extra_count)
                state->count++;
        info->blocked_open--;
#ifdef SERIAL_DEBUG_OPEN
        printk("block_til_ready after blocking: ttys%d, count = %d\n",
               info->line, state->count);
#endif
        if (retval)
                return retval;
        info->flags |= ASYNC_NORMAL_ACTIVE;
        return 0;
}

static int get_async_struct(int line, struct async_struct **ret_info)
{
        struct async_struct *info;
        struct serial_state *sstate;

        sstate = rs_table + line;
        sstate->count++;
        if (sstate->info) {
                *ret_info = sstate->info;
                return 0;
        }
        info = kmalloc(sizeof(struct async_struct), GFP_KERNEL);
        if (!info) {
                sstate->count--;
                return -ENOMEM;
        }
        memset(info, 0, sizeof(struct async_struct));
#ifdef DECLARE_WAITQUEUE
        init_waitqueue_head(&info->open_wait);
        init_waitqueue_head(&info->close_wait);
        init_waitqueue_head(&info->delta_msr_wait);
#endif
        info->magic = SERIAL_MAGIC;
        info->port = sstate->port;
        info->flags = sstate->flags;
        info->xmit_fifo_size = sstate->xmit_fifo_size;
        info->line = line;
        tasklet_init(&info->tlet, do_softint, (unsigned long)info);
        info->state = sstate;
        if (sstate->info) {
                kfree(info);
                *ret_info = sstate->info;
                return 0;
        }
        *ret_info = sstate->info = info;
        return 0;
}

/*
 * 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 async_struct     *info;
        int                     retval, line;
        unsigned long           page;

        line = tty->index;
        if ((line < 0) || (line >= NR_PORTS)) {
                return -ENODEV;
        }
        retval = get_async_struct(line, &info);
        if (retval) {
                return retval;
        }
        tty->driver_data = info;
        info->tty = tty;
        if (serial_paranoia_check(info, tty->name, "rs_open"))
                return -ENODEV;

#ifdef SERIAL_DEBUG_OPEN
        printk("rs_open %s, count = %d\n", tty->name, info->state->count);
#endif
        info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

        if (!tmp_buf) {
                page = get_zeroed_page(GFP_KERNEL);
                if (!page) {
                        return -ENOMEM;
                }
                if (tmp_buf)
                        free_page(page);
                else
                        tmp_buf = (unsigned char *) page;
        }

        /*
         * If the port is the middle of closing, bail out now
         */
        if (tty_hung_up_p(filp) ||
            (info->flags & ASYNC_CLOSING)) {
                if (info->flags & ASYNC_CLOSING)
                        interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
                return ((info->flags & ASYNC_HUP_NOTIFY) ?
                        -EAGAIN : -ERESTARTSYS);
#else
                return -EAGAIN;
#endif
        }

        /*
         * Start up serial port
         */
        retval = startup(info);
        if (retval) {
                return retval;
        }

        retval = block_til_ready(tty, filp, info);
        if (retval) {
#ifdef SERIAL_DEBUG_OPEN
                printk("rs_open returning after block_til_ready with %d\n",
                       retval);
#endif
                return retval;
        }

#ifdef SERIAL_DEBUG_OPEN
        printk("rs_open %s successful...", tty->name);
#endif
        return 0;
}

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

static inline int line_info(char *buf, struct serial_state *state)
{
        struct async_struct *info = state->info, scr_info;
        char    stat_buf[30], control, status;
        int     ret;
        unsigned long flags;

        ret = sprintf(buf, "%d: uart:amiga_builtin",state->line);

        /*
         * Figure out the current RS-232 lines
         */
        if (!info) {
                info = &scr_info;       /* This is just for serial_{in,out} */

                info->magic = SERIAL_MAGIC;
                info->flags = state->flags;
                info->quot = 0;
                info->tty = NULL;
        }
        local_irq_save(flags);
        status = ciab.pra;
        control = info ? info->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 (info->quot) {
                ret += sprintf(buf+ret, " baud:%d",
                               state->baud_base / info->quot);
        }

        ret += sprintf(buf+ret, " tx:%d rx:%d",
                      state->icount.tx, state->icount.rx);

        if (state->icount.frame)
                ret += sprintf(buf+ret, " fe:%d", state->icount.frame);

        if (state->icount.parity)
                ret += sprintf(buf+ret, " pe:%d", state->icount.parity);

        if (state->icount.brk)
                ret += sprintf(buf+ret, " brk:%d", state->icount.brk);

        if (state->icount.overrun)
                ret += sprintf(buf+ret, " oe:%d", state->icount.overrun);

        /*
         * Last thing is the RS-232 status lines
         */
        ret += sprintf(buf+ret, " %s\n", stat_buf+1);
        return ret;
}

static int rs_read_proc(char *page, char **start, off_t off, int count,
                        int *eof, void *data)
{
        int len = 0, l;
        off_t   begin = 0;

        len += sprintf(page, "serinfo:1.0 driver:%s\n", serial_version);
        l = line_info(page + len, &rs_table[0]);
        len += l;
        if (len+begin > off+count)
          goto done;
        if (len+begin < off) {
          begin += len;
          len = 0;
        }
        *eof = 1;
done:
        if (off >= len+begin)
                return 0;
        *start = page + (off-begin);
        return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * ---------------------------------------------------------------------
 * 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 _INLINE_ void show_serial_version(void)
{
        printk(KERN_INFO "%s version %s\n", serial_name, serial_version);
}


static 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,
        .read_proc = rs_read_proc,
        .tiocmget = rs_tiocmget,
        .tiocmset = rs_tiocmset,
};

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

        if (!MACH_IS_AMIGA || !AMIGAHW_PRESENT(AMI_SERIAL))
                return -ENODEV;

        serial_driver = alloc_tty_driver(1);
        if (!serial_driver)
                return -ENOMEM;

        /*
         *  We request SERDAT and SERPER only, because the serial registers are
         *  too spreaded over the custom register space
         */
        if (!request_mem_region(CUSTOM_PHYSADDR+0x30, 4, "amiserial [Paula]"))
                return -EBUSY;

        IRQ_ports = NULL;

        show_serial_version();

        /* Initialize the tty_driver structure */

        serial_driver->owner = THIS_MODULE;
        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);

        if (tty_register_driver(serial_driver))
                panic("Couldn't register serial driver\n");

        state = rs_table;
        state->magic = SSTATE_MAGIC;
        state->port = (int)&custom.serdatr; /* Just to give it a value */
        state->line = 0;
        state->custom_divisor = 0;
        state->close_delay = 5*HZ/10;
        state->closing_wait = 30*HZ;
        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;

        printk(KERN_INFO "ttyS%d is the amiga builtin serial port\n",
                       state->line);

        /* Hardware set up */

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

        local_irq_save(flags);

        /* set ISRs, and then disable the rx interrupts */
        request_irq(IRQ_AMIGA_TBE, ser_tx_int, 0, "serial TX", state);
        request_irq(IRQ_AMIGA_RBF, ser_rx_int, SA_INTERRUPT, "serial RX", state);

        /* 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 */

        return 0;
}

static __exit void rs_exit(void) 
{
        int error;
        struct async_struct *info = rs_table[0].info;

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

        if (info) {
          rs_table[0].info = NULL;
          kfree(info);
        }

        if (tmp_buf) {
                free_page((unsigned long) tmp_buf);
                tmp_buf = NULL;
        }

        release_mem_region(CUSTOM_PHYSADDR+0x30, 4);
}

module_init(rs_init)
module_exit(rs_exit)


/*
 * ------------------------------------------------------------
 * Serial console driver
 * ------------------------------------------------------------
 */
#ifdef CONFIG_SERIAL_CONSOLE

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

MODULE_LICENSE("GPL");