Linux 2.6.31.8

[linux/fpc-iii.git] / arch / ia64 / hp / sim / simserial.c

/*
 * Simulated Serial Driver (fake serial)
 *
 * This driver is mostly used for bringup purposes and will go away.
 * It has a strong dependency on the system console. All outputs
 * are rerouted to the same facility as the one used by printk which, in our
 * case means sys_sim.c console (goes via the simulator). The code hereafter
 * is completely leveraged from the serial.c driver.
 *
 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
 *      Stephane Eranian <eranian@hpl.hp.com>
 *      David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 02/04/00 D. Mosberger        Merged in serial.c bug fixes in rs_close().
 * 02/25/00 D. Mosberger        Synced up with 2.3.99pre-5 version of serial.c.
 * 07/30/02 D. Mosberger        Replace sti()/cli() with explicit spinlocks & local irq masking
 */

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/sysrq.h>

#include <asm/irq.h>
#include <asm/hw_irq.h>
#include <asm/uaccess.h>

#undef SIMSERIAL_DEBUG  /* define this to get some debug information */

#define KEYBOARD_INTR   3       /* must match with simulator! */

#define NR_PORTS        1       /* only one port for now */

#define IRQ_T(info) ((info->flags & ASYNC_SHARE_IRQ) ? IRQF_SHARED : IRQF_DISABLED)

#define SSC_GETCHAR     21

extern long ia64_ssc (long, long, long, long, int);
extern void ia64_ssc_connect_irq (long intr, long irq);

static char *serial_name = "SimSerial driver";
static char *serial_version = "0.6";

/*
 * This has been extracted from asm/serial.h. We need one eventually but
 * I don't know exactly what we're going to put in it so just fake one
 * for now.
 */
#define BASE_BAUD ( 1843200 / 16 )

#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)

/*
 * Most of the values here are meaningless to this particular driver.
 * However some values must be preserved for the code (leveraged from serial.c
 * to work correctly).
 * port must not be 0
 * type must not be UNKNOWN
 * So I picked arbitrary (guess from where?) values instead
 */
static struct serial_state rs_table[NR_PORTS]={
  /* UART CLK   PORT IRQ     FLAGS        */
  { 0, BASE_BAUD, 0x3F8, 0, STD_COM_FLAGS,0,PORT_16550 }  /* ttyS0 */
};

/*
 * Just for the fun of it !
 */
static struct serial_uart_config uart_config[] = {
        { "unknown", 1, 0 },
        { "8250", 1, 0 },
        { "16450", 1, 0 },
        { "16550", 1, 0 },
        { "16550A", 16, UART_CLEAR_FIFO | UART_USE_FIFO },
        { "cirrus", 1, 0 },
        { "ST16650", 1, UART_CLEAR_FIFO | UART_STARTECH },
        { "ST16650V2", 32, UART_CLEAR_FIFO | UART_USE_FIFO |
                  UART_STARTECH },
        { "TI16750", 64, UART_CLEAR_FIFO | UART_USE_FIFO},
        { NULL, 0}
};

struct tty_driver *hp_simserial_driver;

static struct async_struct *IRQ_ports[NR_IRQS];

static struct console *console;

static unsigned char *tmp_buf;

extern struct console *console_drivers; /* from kernel/printk.c */

/*
 * ------------------------------------------------------------
 * 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)
{
#ifdef SIMSERIAL_DEBUG
        printk("rs_stop: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
                tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif

}

static void rs_start(struct tty_struct *tty)
{
#ifdef SIMSERIAL_DEBUG
        printk("rs_start: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
                tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif
}

static  void receive_chars(struct tty_struct *tty)
{
        unsigned char ch;
        static unsigned char seen_esc = 0;

        while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
                if ( ch == 27 && seen_esc == 0 ) {
                        seen_esc = 1;
                        continue;
                } else {
                        if ( seen_esc==1 && ch == 'O' ) {
                                seen_esc = 2;
                                continue;
                        } else if ( seen_esc == 2 ) {
                                if ( ch == 'P' ) /* F1 */
                                        show_state();
#ifdef CONFIG_MAGIC_SYSRQ
                                if ( ch == 'S' ) { /* F4 */
                                        do
                                                ch = ia64_ssc(0, 0, 0, 0,
                                                              SSC_GETCHAR);
                                        while (!ch);
                                        handle_sysrq(ch, NULL);
                                }
#endif
                                seen_esc = 0;
                                continue;
                        }
                }
                seen_esc = 0;

                if (tty_insert_flip_char(tty, ch, TTY_NORMAL) == 0)
                        break;
        }
        tty_flip_buffer_push(tty);
}

/*
 * This is the serial driver's interrupt routine for a single port
 */
static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
{
        struct async_struct * info;

        /*
         * I don't know exactly why they don't use the dev_id opaque data
         * pointer instead of this extra lookup table
         */
        info = IRQ_ports[irq];
        if (!info || !info->tty) {
                printk(KERN_INFO "simrs_interrupt_single: info|tty=0 info=%p problem\n", info);
                return IRQ_NONE;
        }
        /*
         * pretty simple in our case, because we only get interrupts
         * on inbound traffic
         */
        receive_chars(info->tty);
        return IRQ_HANDLED;
}

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

static void do_softint(struct work_struct *private_)
{
        printk(KERN_ERR "simserial: do_softint called\n");
}

static int rs_put_char(struct tty_struct *tty, unsigned char ch)
{
        struct async_struct *info = (struct async_struct *)tty->driver_data;
        unsigned long flags;

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

        local_irq_save(flags);
        if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
                local_irq_restore(flags);
                return 0;
        }
        info->xmit.buf[info->xmit.head] = ch;
        info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
        local_irq_restore(flags);
        return 1;
}

static void transmit_chars(struct async_struct *info, int *intr_done)
{
        int count;
        unsigned long flags;


        local_irq_save(flags);

        if (info->x_char) {
                char c = info->x_char;

                console->write(console, &c, 1);

                info->state->icount.tx++;
                info->x_char = 0;

                goto out;
        }

        if (info->xmit.head == info->xmit.tail || info->tty->stopped || info->tty->hw_stopped) {
#ifdef SIMSERIAL_DEBUG
                printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
                       info->xmit.head, info->xmit.tail, info->tty->stopped);
#endif
                goto out;
        }
        /*
         * We removed the loop and try to do it in to chunks. We need
         * 2 operations maximum because it's a ring buffer.
         *
         * First from current to tail if possible.
         * Then from the beginning of the buffer until necessary
         */

        count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
                    SERIAL_XMIT_SIZE - info->xmit.tail);
        console->write(console, info->xmit.buf+info->xmit.tail, count);

        info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);

        /*
         * We have more at the beginning of the buffer
         */
        count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
        if (count) {
                console->write(console, info->xmit.buf, count);
                info->xmit.tail += count;
        }
out:
        local_irq_restore(flags);
}

static void rs_flush_chars(struct tty_struct *tty)
{
        struct async_struct *info = (struct async_struct *)tty->driver_data;

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

        transmit_chars(info, NULL);
}


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

        if (!tty || !info->xmit.buf || !tmp_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);
        /*
         * Hey, we transmit directly from here in our case
         */
        if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE)
            && !tty->stopped && !tty->hw_stopped) {
                transmit_chars(info, NULL);
        }
        return ret;
}

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

        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;

        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;

        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;

        info->x_char = ch;
        if (ch) {
                /*
                 * I guess we could call console->write() directly but
                 * let's do that for now.
                 */
                transmit_chars(info, NULL);
        }
}

/*
 * ------------------------------------------------------------
 * 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)
{
        if (I_IXOFF(tty)) rs_send_xchar(tty, STOP_CHAR(tty));

        printk(KERN_INFO "simrs_throttle called\n");
}

static void rs_unthrottle(struct tty_struct * tty)
{
        struct async_struct *info = (struct async_struct *)tty->driver_data;

        if (I_IXOFF(tty)) {
                if (info->x_char)
                        info->x_char = 0;
                else
                        rs_send_xchar(tty, START_CHAR(tty));
        }
        printk(KERN_INFO "simrs_unthrottle called\n");
}


static int rs_ioctl(struct tty_struct *tty, struct file * file,
                    unsigned int cmd, unsigned long arg)
{
        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:
                        printk(KERN_INFO "simrs_ioctl TIOCGSERIAL called\n");
                        return 0;
                case TIOCSSERIAL:
                        printk(KERN_INFO "simrs_ioctl TIOCSSERIAL called\n");
                        return 0;
                case TIOCSERCONFIG:
                        printk(KERN_INFO "rs_ioctl: TIOCSERCONFIG called\n");
                        return -EINVAL;

                case TIOCSERGETLSR: /* Get line status register */
                        printk(KERN_INFO "rs_ioctl: TIOCSERGETLSR called\n");
                        return  -EINVAL;

                case TIOCSERGSTRUCT:
                        printk(KERN_INFO "rs_ioctl: TIOCSERGSTRUCT called\n");
#if 0
                        if (copy_to_user((struct async_struct *) arg,
                                         info, sizeof(struct async_struct)))
                                return -EFAULT;
#endif
                        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:
                        printk(KERN_INFO "rs_ioctl: TIOCMIWAIT: called\n");
                        return 0;
                /*
                 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
                 * Return: write counters to the user passed counter struct
                 * NB: both 1->0 and 0->1 transitions are counted except for
                 *     RI where only 0->1 is counted.
                 */
                case TIOCGICOUNT:
                        printk(KERN_INFO "rs_ioctl: TIOCGICOUNT called\n");
                        return 0;

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

                default:
                        return -ENOIOCTLCMD;
                }
        return 0;
}

#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
        /* Handle turning off CRTSCTS */
        if ((old_termios->c_cflag & CRTSCTS) &&
            !(tty->termios->c_cflag & CRTSCTS)) {
                tty->hw_stopped = 0;
                rs_start(tty);
        }
}
/*
 * 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;
        int             retval;

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

        state = info->state;

#ifdef SIMSERIAL_DEBUG
        printk("Shutting down serial port %d (irq %d)....", info->line,
               state->irq);
#endif

        local_irq_save(flags);
        {
                /*
                 * First unlink the serial port from the IRQ chain...
                 */
                if (info->next_port)
                        info->next_port->prev_port = info->prev_port;
                if (info->prev_port)
                        info->prev_port->next_port = info->next_port;
                else
                        IRQ_ports[state->irq] = info->next_port;

                /*
                 * Free the IRQ, if necessary
                 */
                if (state->irq && (!IRQ_ports[state->irq] ||
                                   !IRQ_ports[state->irq]->next_port)) {
                        if (IRQ_ports[state->irq]) {
                                free_irq(state->irq, NULL);
                                retval = request_irq(state->irq, rs_interrupt_single,
                                                     IRQ_T(info), "serial", NULL);

                                if (retval)
                                        printk(KERN_ERR "serial shutdown: request_irq: error %d"
                                               "  Couldn't reacquire IRQ.\n", retval);
                        } else
                                free_irq(state->irq, NULL);
                }

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

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

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

/*
 * ------------------------------------------------------------
 * 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 ) return;

        state = info->state;

        local_irq_save(flags);
        if (tty_hung_up_p(filp)) {
#ifdef SIMSERIAL_DEBUG
                printk("rs_close: hung_up\n");
#endif
                local_irq_restore(flags);
                return;
        }
#ifdef SIMSERIAL_DEBUG
        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(KERN_ERR "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(KERN_ERR "rs_close: bad serial port count for ttys%d: %d\n",
                       info->line, state->count);
                state->count = 0;
        }
        if (state->count) {
                local_irq_restore(flags);
                return;
        }
        info->flags |= ASYNC_CLOSING;
        local_irq_restore(flags);

        /*
         * Now we wait for the transmit buffer to clear; and we notify
         * the line discipline to only process XON/XOFF characters.
         */
        shutdown(info);
        rs_flush_buffer(tty);
        tty_ldisc_flush(tty);
        info->event = 0;
        info->tty = NULL;
        if (info->blocked_open) {
                if (info->close_delay)
                        schedule_timeout_interruptible(info->close_delay);
                wake_up_interruptible(&info->open_wait);
        }
        info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
        wake_up_interruptible(&info->close_wait);
}

/*
 * rs_wait_until_sent() --- wait until the transmitter is empty
 */
static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
}


/*
 * 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;

#ifdef SIMSERIAL_DEBUG
        printk("rs_hangup: called\n");
#endif

        state = info->state;

        rs_flush_buffer(tty);
        if (info->flags & ASYNC_CLOSING)
                return;
        shutdown(info);

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


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;
        }
        init_waitqueue_head(&info->open_wait);
        init_waitqueue_head(&info->close_wait);
        init_waitqueue_head(&info->delta_msr_wait);
        info->magic = SERIAL_MAGIC;
        info->port = sstate->port;
        info->flags = sstate->flags;
        info->xmit_fifo_size = sstate->xmit_fifo_size;
        info->line = line;
        INIT_WORK(&info->work, do_softint);
        info->state = sstate;
        if (sstate->info) {
                kfree(info);
                *ret_info = sstate->info;
                return 0;
        }
        *ret_info = sstate->info = info;
        return 0;
}

static int
startup(struct async_struct *info)
{
        unsigned long flags;
        int     retval=0;
        irq_handler_t handler;
        struct serial_state *state= info->state;
        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 (!state->port || !state->type) {
                if (info->tty) set_bit(TTY_IO_ERROR, &info->tty->flags);
                free_page(page);
                goto errout;
        }
        if (info->xmit.buf)
                free_page(page);
        else
                info->xmit.buf = (unsigned char *) page;

#ifdef SIMSERIAL_DEBUG
        printk("startup: ttys%d (irq %d)...", info->line, state->irq);
#endif

        /*
         * Allocate the IRQ if necessary
         */
        if (state->irq && (!IRQ_ports[state->irq] ||
                          !IRQ_ports[state->irq]->next_port)) {
                if (IRQ_ports[state->irq]) {
                        retval = -EBUSY;
                        goto errout;
                } else
                        handler = rs_interrupt_single;

                retval = request_irq(state->irq, handler, IRQ_T(info), "simserial", NULL);
                if (retval) {
                        if (capable(CAP_SYS_ADMIN)) {
                                if (info->tty)
                                        set_bit(TTY_IO_ERROR,
                                                &info->tty->flags);
                                retval = 0;
                        }
                        goto errout;
                }
        }

        /*
         * Insert serial port into IRQ chain.
         */
        info->prev_port = NULL;
        info->next_port = IRQ_ports[state->irq];
        if (info->next_port)
                info->next_port->prev_port = info;
        IRQ_ports[state->irq] = info;

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

        info->xmit.head = info->xmit.tail = 0;

#if 0
        /*
         * Set up serial timers...
         */
        timer_table[RS_TIMER].expires = jiffies + 2*HZ/100;
        timer_active |= 1 << RS_TIMER;
#endif

        /*
         * 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;
        }

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

errout:
        local_irq_restore(flags);
        return retval;
}


/*
 * 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;

#ifdef SIMSERIAL_DEBUG
        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;
        }

        /*
         * figure out which console to use (should be one already)
         */
        console = console_drivers;
        while (console) {
                if ((console->flags & CON_ENABLED) && console->write) break;
                console = console->next;
        }

#ifdef SIMSERIAL_DEBUG
        printk("rs_open ttys%d successful\n", info->line);
#endif
        return 0;
}

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

static inline void line_info(struct seq_file *m, struct serial_state *state)
{
        seq_printf(m, "%d: uart:%s port:%lX irq:%d\n",
                       state->line, uart_config[state->type].name,
                       state->port, state->irq);
}

static int rs_proc_show(struct seq_file *m, void *v)
{
        int i;

        seq_printf(m, "simserinfo:1.0 driver:%s\n", serial_version);
        for (i = 0; i < NR_PORTS; i++)
                line_info(m, &rs_table[i]);
        return 0;
}

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

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

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

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static inline void show_serial_version(void)
{
        printk(KERN_INFO "%s version %s with", serial_name, serial_version);
        printk(KERN_INFO " no serial options enabled\n");
}

static const struct tty_operations hp_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,
        .send_xchar = rs_send_xchar,
        .set_termios = rs_set_termios,
        .stop = rs_stop,
        .start = rs_start,
        .hangup = rs_hangup,
        .wait_until_sent = rs_wait_until_sent,
        .proc_fops = &rs_proc_fops,
};

/*
 * The serial driver boot-time initialization code!
 */
static int __init
simrs_init (void)
{
        int                     i, rc;
        struct serial_state     *state;

        if (!ia64_platform_is("hpsim"))
                return -ENODEV;

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

        show_serial_version();

        /* Initialize the tty_driver structure */

        hp_simserial_driver->owner = THIS_MODULE;
        hp_simserial_driver->driver_name = "simserial";
        hp_simserial_driver->name = "ttyS";
        hp_simserial_driver->major = TTY_MAJOR;
        hp_simserial_driver->minor_start = 64;
        hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
        hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
        hp_simserial_driver->init_termios = tty_std_termios;
        hp_simserial_driver->init_termios.c_cflag =
                B9600 | CS8 | CREAD | HUPCL | CLOCAL;
        hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
        tty_set_operations(hp_simserial_driver, &hp_ops);

        /*
         * Let's have a little bit of fun !
         */
        for (i = 0, state = rs_table; i < NR_PORTS; i++,state++) {

                if (state->type == PORT_UNKNOWN) continue;

                if (!state->irq) {
                        if ((rc = assign_irq_vector(AUTO_ASSIGN)) < 0)
                                panic("%s: out of interrupt vectors!\n",
                                      __func__);
                        state->irq = rc;
                        ia64_ssc_connect_irq(KEYBOARD_INTR, state->irq);
                }

                printk(KERN_INFO "ttyS%d at 0x%04lx (irq = %d) is a %s\n",
                       state->line,
                       state->port, state->irq,
                       uart_config[state->type].name);
        }

        if (tty_register_driver(hp_simserial_driver))
                panic("Couldn't register simserial driver\n");

        return 0;
}

#ifndef MODULE
__initcall(simrs_init);
#endif