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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/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->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>

#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 struct async_struct *IRQ_ports;

static unsigned char current_ctl_bits;

static void change_speed(struct async_struct *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 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 void rs_sched_event(struct async_struct *info,
                     int event)
{
      info->event |= 1 << event;
      tasklet_schedule(&info->tlet);
}

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

      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;
      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->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 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 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)
{
        /* 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 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 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);
}

/*
 * ---------------------------------------------------------------
 * 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 ktermios *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) {
            /* FIXME: Will need updating for new tty in the end */
            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
       */

      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)
            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 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);
      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 __user * 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 __user * 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 __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 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;
      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(info, argp);
            case TIOCSSERIAL:
                  return set_serial_info(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 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(argp, &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 ktermios *old_termios)
{
      struct async_struct *info = (struct async_struct *)tty->driver_data;
      unsigned long flags;
      unsigned int cflag = tty->termios->c_cflag;

      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;
      }
      __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 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();
      }
      __set_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 = kzalloc(sizeof(struct async_struct), GFP_KERNEL);
      if (!info) {
            sstate->count--;
            return -ENOMEM;
      }
#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;

      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 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 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,
      .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, IRQF_DISABLED, "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);
      }

      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");

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