serial_core.c

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/*
 *  Driver core for serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright 1999 ARM Limited
 *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/serial.h> /* for serial_state and serial_icounter_struct */
#include <linux/serial_core.h>
#include <linux/delay.h>
#include <linux/mutex.h>

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

/*
 * This is used to lock changes in serial line configuration.
 */
static DEFINE_MUTEX(port_mutex);

/*
 * lockdep: port->lock is initialized in two places, but we
 *          want only one lock-class:
 */
static struct lock_class_key port_lock_key;

#define HIGH_BITS_OFFSET    ((sizeof(long)-sizeof(int))*8)

#ifdef CONFIG_SERIAL_CORE_CONSOLE
#define uart_console(port)  ((port)->cons && (port)->cons->index == (port)->line)
#else
#define uart_console(port)  (0)
#endif

static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
                    struct ktermios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
static void uart_change_pm(struct uart_state *state, int pm_state);

static void uart_port_shutdown(struct tty_port *port);

/*
 * This routine is used by the interrupt handler to schedule processing in
 * the software interrupt portion of the driver.
 */
void uart_write_wakeup(struct uart_port *port)
{
    struct uart_state *state = port->state;
    /*
     * This means you called this function _after_ the port was
     * closed.  No cookie for you.
     */
    BUG_ON(!state);
    tty_wakeup(state->port.tty);
}

static void uart_stop(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port = state->uart_port;
    unsigned long flags;

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

static void __uart_start(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port = state->uart_port;

    if (!uart_circ_empty(&state->xmit) && state->xmit.buf &&
        !tty->stopped && !tty->hw_stopped)
        port->ops->start_tx(port);
}

static void uart_start(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port = state->uart_port;
    unsigned long flags;

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

static inline void
uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
{
    unsigned long flags;
    unsigned int old;

    spin_lock_irqsave(&port->lock, flags);
    old = port->mctrl;
    port->mctrl = (old & ~clear) | set;
    if (old != port->mctrl)
        port->ops->set_mctrl(port, port->mctrl);
    spin_unlock_irqrestore(&port->lock, flags);
}

#define uart_set_mctrl(port, set)   uart_update_mctrl(port, set, 0)
#define uart_clear_mctrl(port, clear)   uart_update_mctrl(port, 0, clear)

/*
 * Startup the port.  This will be called once per open.  All calls
 * will be serialised by the per-port mutex.
 */
static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
        int init_hw)
{
    struct uart_port *uport = state->uart_port;
    struct tty_port *port = &state->port;
    unsigned long page;
    int retval = 0;

    if (uport->type == PORT_UNKNOWN)
        return 1;

    /*
     * Initialise and allocate the transmit and temporary
     * buffer.
     */
    if (!state->xmit.buf) {
        /* This is protected by the per port mutex */
        page = get_zeroed_page(GFP_KERNEL);
        if (!page)
            return -ENOMEM;

        state->xmit.buf = (unsigned char *) page;
        uart_circ_clear(&state->xmit);
    }

    retval = uport->ops->startup(uport);
    if (retval == 0) {
        if (uart_console(uport) && uport->cons->cflag) {
            tty->termios.c_cflag = uport->cons->cflag;
            uport->cons->cflag = 0;
        }
        /*
         * Initialise the hardware port settings.
         */
        uart_change_speed(tty, state, NULL);

        if (init_hw) {
            /*
             * Setup the RTS and DTR signals once the
             * port is open and ready to respond.
             */
            if (tty->termios.c_cflag & CBAUD)
                uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
        }

        if (tty_port_cts_enabled(port)) {
            spin_lock_irq(&uport->lock);
            if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
                tty->hw_stopped = 1;
            spin_unlock_irq(&uport->lock);
        }
    }

    /*
     * This is to allow setserial on this port. People may want to set
     * port/irq/type and then reconfigure the port properly if it failed
     * now.
     */
    if (retval && capable(CAP_SYS_ADMIN))
        return 1;

    return retval;
}

static int uart_startup(struct tty_struct *tty, struct uart_state *state,
        int init_hw)
{
    struct tty_port *port = &state->port;
    int retval;

    if (port->flags & ASYNC_INITIALIZED)
        return 0;

    /*
     * Set the TTY IO error marker - we will only clear this
     * once we have successfully opened the port.
     */
    set_bit(TTY_IO_ERROR, &tty->flags);

    retval = uart_port_startup(tty, state, init_hw);
    if (!retval) {
        set_bit(ASYNCB_INITIALIZED, &port->flags);
        clear_bit(TTY_IO_ERROR, &tty->flags);
    } else if (retval > 0)
        retval = 0;

    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.  Calls to
 * uart_shutdown are serialised by the per-port semaphore.
 */
static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
{
    struct uart_port *uport = state->uart_port;
    struct tty_port *port = &state->port;

    /*
     * Set the TTY IO error marker
     */
    if (tty)
        set_bit(TTY_IO_ERROR, &tty->flags);

    if (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) {
        /*
         * Turn off DTR and RTS early.
         */
        if (!tty || (tty->termios.c_cflag & HUPCL))
            uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);

        uart_port_shutdown(port);
    }

    /*
     * It's possible for shutdown to be called after suspend if we get
     * a DCD drop (hangup) at just the right time.  Clear suspended bit so
     * we don't try to resume a port that has been shutdown.
     */
    clear_bit(ASYNCB_SUSPENDED, &port->flags);

    /*
     * Free the transmit buffer page.
     */
    if (state->xmit.buf) {
        free_page((unsigned long)state->xmit.buf);
        state->xmit.buf = NULL;
    }
}

void
uart_update_timeout(struct uart_port *port, unsigned int cflag,
            unsigned int baud)
{
    unsigned int bits;

    /* byte size and parity */
    switch (cflag & CSIZE) {
    case CS5:
        bits = 7;
        break;
    case CS6:
        bits = 8;
        break;
    case CS7:
        bits = 9;
        break;
    default:
        bits = 10;
        break; /* CS8 */
    }

    if (cflag & CSTOPB)
        bits++;
    if (cflag & PARENB)
        bits++;

    /*
     * The total number of bits to be transmitted in the fifo.
     */
    bits = bits * port->fifosize;

    /*
     * Figure the timeout to send the above number of bits.
     * Add .02 seconds of slop
     */
    port->timeout = (HZ * bits) / baud + HZ/50;
}

EXPORT_SYMBOL(uart_update_timeout);

unsigned int
uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
           struct ktermios *old, unsigned int min, unsigned int max)
{
    unsigned int try, baud, altbaud = 38400;
    int hung_up = 0;
    upf_t flags = port->flags & UPF_SPD_MASK;

    if (flags == UPF_SPD_HI)
        altbaud = 57600;
    else if (flags == UPF_SPD_VHI)
        altbaud = 115200;
    else if (flags == UPF_SPD_SHI)
        altbaud = 230400;
    else if (flags == UPF_SPD_WARP)
        altbaud = 460800;

    for (try = 0; try < 2; try++) {
        baud = tty_termios_baud_rate(termios);

        /*
         * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
         * Die! Die! Die!
         */
        if (baud == 38400)
            baud = altbaud;

        /*
         * Special case: B0 rate.
         */
        if (baud == 0) {
            hung_up = 1;
            baud = 9600;
        }

        if (baud >= min && baud <= max)
            return baud;

        /*
         * Oops, the quotient was zero.  Try again with
         * the old baud rate if possible.
         */
        termios->c_cflag &= ~CBAUD;
        if (old) {
            baud = tty_termios_baud_rate(old);
            if (!hung_up)
                tty_termios_encode_baud_rate(termios,
                                baud, baud);
            old = NULL;
            continue;
        }

        /*
         * As a last resort, if the range cannot be met then clip to
         * the nearest chip supported rate.
         */
        if (!hung_up) {
            if (baud <= min)
                tty_termios_encode_baud_rate(termios,
                            min + 1, min + 1);
            else
                tty_termios_encode_baud_rate(termios,
                            max - 1, max - 1);
        }
    }
    /* Should never happen */
    WARN_ON(1);
    return 0;
}

EXPORT_SYMBOL(uart_get_baud_rate);

unsigned int
uart_get_divisor(struct uart_port *port, unsigned int baud)
{
    unsigned int quot;

    /*
     * Old custom speed handling.
     */
    if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
        quot = port->custom_divisor;
    else
        quot = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);

    return quot;
}

EXPORT_SYMBOL(uart_get_divisor);

/* FIXME: Consistent locking policy */
static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
                    struct ktermios *old_termios)
{
    struct tty_port *port = &state->port;
    struct uart_port *uport = state->uart_port;
    struct ktermios *termios;

    /*
     * If we have no tty, termios, or the port does not exist,
     * then we can't set the parameters for this port.
     */
    if (!tty || uport->type == PORT_UNKNOWN)
        return;

    termios = &tty->termios;

    /*
     * Set flags based on termios cflag
     */
    if (termios->c_cflag & CRTSCTS)
        set_bit(ASYNCB_CTS_FLOW, &port->flags);
    else
        clear_bit(ASYNCB_CTS_FLOW, &port->flags);

    if (termios->c_cflag & CLOCAL)
        clear_bit(ASYNCB_CHECK_CD, &port->flags);
    else
        set_bit(ASYNCB_CHECK_CD, &port->flags);

    uport->ops->set_termios(uport, termios, old_termios);
}

static inline int __uart_put_char(struct uart_port *port,
                struct circ_buf *circ, unsigned char c)
{
    unsigned long flags;
    int ret = 0;

    if (!circ->buf)
        return 0;

    spin_lock_irqsave(&port->lock, flags);
    if (uart_circ_chars_free(circ) != 0) {
        circ->buf[circ->head] = c;
        circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
        ret = 1;
    }
    spin_unlock_irqrestore(&port->lock, flags);
    return ret;
}

static int uart_put_char(struct tty_struct *tty, unsigned char ch)
{
    struct uart_state *state = tty->driver_data;

    return __uart_put_char(state->uart_port, &state->xmit, ch);
}

static void uart_flush_chars(struct tty_struct *tty)
{
    uart_start(tty);
}

static int uart_write(struct tty_struct *tty,
                    const unsigned char *buf, int count)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port;
    struct circ_buf *circ;
    unsigned long flags;
    int c, ret = 0;

    /*
     * This means you called this function _after_ the port was
     * closed.  No cookie for you.
     */
    if (!state) {
        WARN_ON(1);
        return -EL3HLT;
    }

    port = state->uart_port;
    circ = &state->xmit;

    if (!circ->buf)
        return 0;

    spin_lock_irqsave(&port->lock, flags);
    while (1) {
        c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
        if (count < c)
            c = count;
        if (c <= 0)
            break;
        memcpy(circ->buf + circ->head, buf, c);
        circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
        buf += c;
        count -= c;
        ret += c;
    }
    spin_unlock_irqrestore(&port->lock, flags);

    uart_start(tty);
    return ret;
}

static int uart_write_room(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    unsigned long flags;
    int ret;

    spin_lock_irqsave(&state->uart_port->lock, flags);
    ret = uart_circ_chars_free(&state->xmit);
    spin_unlock_irqrestore(&state->uart_port->lock, flags);
    return ret;
}

static int uart_chars_in_buffer(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    unsigned long flags;
    int ret;

    spin_lock_irqsave(&state->uart_port->lock, flags);
    ret = uart_circ_chars_pending(&state->xmit);
    spin_unlock_irqrestore(&state->uart_port->lock, flags);
    return ret;
}

static void uart_flush_buffer(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port;
    unsigned long flags;

    /*
     * This means you called this function _after_ the port was
     * closed.  No cookie for you.
     */
    if (!state) {
        WARN_ON(1);
        return;
    }

    port = state->uart_port;
    pr_debug("uart_flush_buffer(%d) called\n", tty->index);

    spin_lock_irqsave(&port->lock, flags);
    uart_circ_clear(&state->xmit);
    if (port->ops->flush_buffer)
        port->ops->flush_buffer(port);
    spin_unlock_irqrestore(&port->lock, flags);
    tty_wakeup(tty);
}

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

    if (port->ops->send_xchar)
        port->ops->send_xchar(port, ch);
    else {
        port->x_char = ch;
        if (ch) {
            spin_lock_irqsave(&port->lock, flags);
            port->ops->start_tx(port);
            spin_unlock_irqrestore(&port->lock, flags);
        }
    }
}

static void uart_throttle(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;

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

    if (tty->termios.c_cflag & CRTSCTS)
        uart_clear_mctrl(state->uart_port, TIOCM_RTS);
}

static void uart_unthrottle(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port = state->uart_port;

    if (I_IXOFF(tty)) {
        if (port->x_char)
            port->x_char = 0;
        else
            uart_send_xchar(tty, START_CHAR(tty));
    }

    if (tty->termios.c_cflag & CRTSCTS)
        uart_set_mctrl(port, TIOCM_RTS);
}

static void uart_get_info(struct tty_port *port,
                        struct uart_state *state,
            struct serial_struct *retinfo)
{
    struct uart_port *uport = state->uart_port;

    memset(retinfo, 0, sizeof(*retinfo));

    retinfo->type       = uport->type;
    retinfo->line       = uport->line;
    retinfo->port       = uport->iobase;
    if (HIGH_BITS_OFFSET)
        retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
    retinfo->irq            = uport->irq;
    retinfo->flags      = uport->flags;
    retinfo->xmit_fifo_size  = uport->fifosize;
    retinfo->baud_base      = uport->uartclk / 16;
    retinfo->close_delay        = jiffies_to_msecs(port->close_delay) / 10;
    retinfo->closing_wait    = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
                ASYNC_CLOSING_WAIT_NONE :
                jiffies_to_msecs(port->closing_wait) / 10;
    retinfo->custom_divisor  = uport->custom_divisor;
    retinfo->hub6       = uport->hub6;
    retinfo->io_type         = uport->iotype;
    retinfo->iomem_reg_shift = uport->regshift;
    retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;
}

static int uart_get_info_user(struct uart_state *state,
             struct serial_struct __user *retinfo)
{
    struct tty_port *port = &state->port;
    struct serial_struct tmp;

    /* Ensure the state we copy is consistent and no hardware changes
       occur as we go */
    mutex_lock(&port->mutex);
    uart_get_info(port, state, &tmp);
    mutex_unlock(&port->mutex);

    if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
        return -EFAULT;
    return 0;
}

static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
             struct uart_state *state,
             struct serial_struct *new_info)
{
    struct uart_port *uport = state->uart_port;
    unsigned long new_port;
    unsigned int change_irq, change_port, closing_wait;
    unsigned int old_custom_divisor, close_delay;
    upf_t old_flags, new_flags;
    int retval = 0;

    new_port = new_info->port;
    if (HIGH_BITS_OFFSET)
        new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;

    new_info->irq = irq_canonicalize(new_info->irq);
    close_delay = msecs_to_jiffies(new_info->close_delay * 10);
    closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
            ASYNC_CLOSING_WAIT_NONE :
            msecs_to_jiffies(new_info->closing_wait * 10);


    change_irq  = !(uport->flags & UPF_FIXED_PORT)
        && new_info->irq != uport->irq;

    /*
     * Since changing the 'type' of the port changes its resource
     * allocations, we should treat type changes the same as
     * IO port changes.
     */
    change_port = !(uport->flags & UPF_FIXED_PORT)
        && (new_port != uport->iobase ||
            (unsigned long)new_info->iomem_base != uport->mapbase ||
            new_info->hub6 != uport->hub6 ||
            new_info->io_type != uport->iotype ||
            new_info->iomem_reg_shift != uport->regshift ||
            new_info->type != uport->type);

    old_flags = uport->flags;
    new_flags = new_info->flags;
    old_custom_divisor = uport->custom_divisor;

    if (!capable(CAP_SYS_ADMIN)) {
        retval = -EPERM;
        if (change_irq || change_port ||
            (new_info->baud_base != uport->uartclk / 16) ||
            (close_delay != port->close_delay) ||
            (closing_wait != port->closing_wait) ||
            (new_info->xmit_fifo_size &&
             new_info->xmit_fifo_size != uport->fifosize) ||
            (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
            goto exit;
        uport->flags = ((uport->flags & ~UPF_USR_MASK) |
                   (new_flags & UPF_USR_MASK));
        uport->custom_divisor = new_info->custom_divisor;
        goto check_and_exit;
    }

    /*
     * Ask the low level driver to verify the settings.
     */
    if (uport->ops->verify_port)
        retval = uport->ops->verify_port(uport, new_info);

    if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
        (new_info->baud_base < 9600))
        retval = -EINVAL;

    if (retval)
        goto exit;

    if (change_port || change_irq) {
        retval = -EBUSY;

        /*
         * Make sure that we are the sole user of this port.
         */
        if (tty_port_users(port) > 1)
            goto exit;

        /*
         * We need to shutdown the serial port at the old
         * port/type/irq combination.
         */
        uart_shutdown(tty, state);
    }

    if (change_port) {
        unsigned long old_iobase, old_mapbase;
        unsigned int old_type, old_iotype, old_hub6, old_shift;

        old_iobase = uport->iobase;
        old_mapbase = uport->mapbase;
        old_type = uport->type;
        old_hub6 = uport->hub6;
        old_iotype = uport->iotype;
        old_shift = uport->regshift;

        /*
         * Free and release old regions
         */
        if (old_type != PORT_UNKNOWN)
            uport->ops->release_port(uport);

        uport->iobase = new_port;
        uport->type = new_info->type;
        uport->hub6 = new_info->hub6;
        uport->iotype = new_info->io_type;
        uport->regshift = new_info->iomem_reg_shift;
        uport->mapbase = (unsigned long)new_info->iomem_base;

        /*
         * Claim and map the new regions
         */
        if (uport->type != PORT_UNKNOWN) {
            retval = uport->ops->request_port(uport);
        } else {
            /* Always success - Jean II */
            retval = 0;
        }

        /*
         * If we fail to request resources for the
         * new port, try to restore the old settings.
         */
        if (retval && old_type != PORT_UNKNOWN) {
            uport->iobase = old_iobase;
            uport->type = old_type;
            uport->hub6 = old_hub6;
            uport->iotype = old_iotype;
            uport->regshift = old_shift;
            uport->mapbase = old_mapbase;
            retval = uport->ops->request_port(uport);
            /*
             * If we failed to restore the old settings,
             * we fail like this.
             */
            if (retval)
                uport->type = PORT_UNKNOWN;

            /*
             * We failed anyway.
             */
            retval = -EBUSY;
            /* Added to return the correct error -Ram Gupta */
            goto exit;
        }
    }

    if (change_irq)
        uport->irq      = new_info->irq;
    if (!(uport->flags & UPF_FIXED_PORT))
        uport->uartclk  = new_info->baud_base * 16;
    uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |
                 (new_flags & UPF_CHANGE_MASK);
    uport->custom_divisor   = new_info->custom_divisor;
    port->close_delay     = close_delay;
    port->closing_wait    = closing_wait;
    if (new_info->xmit_fifo_size)
        uport->fifosize = new_info->xmit_fifo_size;
    if (port->tty)
        port->tty->low_latency =
            (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;

 check_and_exit:
    retval = 0;
    if (uport->type == PORT_UNKNOWN)
        goto exit;
    if (port->flags & ASYNC_INITIALIZED) {
        if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
            old_custom_divisor != uport->custom_divisor) {
            /*
             * If they're setting up a custom divisor or speed,
             * instead of clearing it, then bitch about it. No
             * need to rate-limit; it's CAP_SYS_ADMIN only.
             */
            if (uport->flags & UPF_SPD_MASK) {
                char buf[64];
                printk(KERN_NOTICE
                       "%s sets custom speed on %s. This "
                       "is deprecated.\n", current->comm,
                       tty_name(port->tty, buf));
            }
            uart_change_speed(tty, state, NULL);
        }
    } else
        retval = uart_startup(tty, state, 1);
 exit:
    return retval;
}

static int uart_set_info_user(struct tty_struct *tty, struct uart_state *state,
             struct serial_struct __user *newinfo)
{
    struct serial_struct new_serial;
    struct tty_port *port = &state->port;
    int retval;

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

    /*
     * This semaphore protects port->count.  It is also
     * very useful to prevent opens.  Also, take the
     * port configuration semaphore to make sure that a
     * module insertion/removal doesn't change anything
     * under us.
     */
    mutex_lock(&port->mutex);
    retval = uart_set_info(tty, port, state, &new_serial);
    mutex_unlock(&port->mutex);
    return retval;
}

static int uart_get_lsr_info(struct tty_struct *tty,
            struct uart_state *state, unsigned int __user *value)
{
    struct uart_port *uport = state->uart_port;
    unsigned int result;

    result = uport->ops->tx_empty(uport);

    /*
     * If we're about to load something into the transmit
     * register, we'll pretend the transmitter isn't empty to
     * avoid a race condition (depending on when the transmit
     * interrupt happens).
     */
    if (uport->x_char ||
        ((uart_circ_chars_pending(&state->xmit) > 0) &&
         !tty->stopped && !tty->hw_stopped))
        result &= ~TIOCSER_TEMT;

    return put_user(result, value);
}

static int uart_tiocmget(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct tty_port *port = &state->port;
    struct uart_port *uport = state->uart_port;
    int result = -EIO;

    mutex_lock(&port->mutex);
    if (!(tty->flags & (1 << TTY_IO_ERROR))) {
        result = uport->mctrl;
        spin_lock_irq(&uport->lock);
        result |= uport->ops->get_mctrl(uport);
        spin_unlock_irq(&uport->lock);
    }
    mutex_unlock(&port->mutex);

    return result;
}

static int
uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *uport = state->uart_port;
    struct tty_port *port = &state->port;
    int ret = -EIO;

    mutex_lock(&port->mutex);
    if (!(tty->flags & (1 << TTY_IO_ERROR))) {
        uart_update_mctrl(uport, set, clear);
        ret = 0;
    }
    mutex_unlock(&port->mutex);
    return ret;
}

static int uart_break_ctl(struct tty_struct *tty, int break_state)
{
    struct uart_state *state = tty->driver_data;
    struct tty_port *port = &state->port;
    struct uart_port *uport = state->uart_port;

    mutex_lock(&port->mutex);

    if (uport->type != PORT_UNKNOWN)
        uport->ops->break_ctl(uport, break_state);

    mutex_unlock(&port->mutex);
    return 0;
}

static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
{
    struct uart_port *uport = state->uart_port;
    struct tty_port *port = &state->port;
    int flags, ret;

    if (!capable(CAP_SYS_ADMIN))
        return -EPERM;

    /*
     * Take the per-port semaphore.  This prevents count from
     * changing, and hence any extra opens of the port while
     * we're auto-configuring.
     */
    if (mutex_lock_interruptible(&port->mutex))
        return -ERESTARTSYS;

    ret = -EBUSY;
    if (tty_port_users(port) == 1) {
        uart_shutdown(tty, state);

        /*
         * If we already have a port type configured,
         * we must release its resources.
         */
        if (uport->type != PORT_UNKNOWN)
            uport->ops->release_port(uport);

        flags = UART_CONFIG_TYPE;
        if (uport->flags & UPF_AUTO_IRQ)
            flags |= UART_CONFIG_IRQ;

        /*
         * This will claim the ports resources if
         * a port is found.
         */
        uport->ops->config_port(uport, flags);

        ret = uart_startup(tty, state, 1);
    }
    mutex_unlock(&port->mutex);
    return ret;
}

/*
 * 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
 *
 * FIXME: This wants extracting into a common all driver implementation
 * of TIOCMWAIT using tty_port.
 */
static int
uart_wait_modem_status(struct uart_state *state, unsigned long arg)
{
    struct uart_port *uport = state->uart_port;
    struct tty_port *port = &state->port;
    DECLARE_WAITQUEUE(wait, current);
    struct uart_icount cprev, cnow;
    int ret;

    /*
     * note the counters on entry
     */
    spin_lock_irq(&uport->lock);
    memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));

    /*
     * Force modem status interrupts on
     */
    uport->ops->enable_ms(uport);
    spin_unlock_irq(&uport->lock);

    add_wait_queue(&port->delta_msr_wait, &wait);
    for (;;) {
        spin_lock_irq(&uport->lock);
        memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
        spin_unlock_irq(&uport->lock);

        set_current_state(TASK_INTERRUPTIBLE);

        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))) {
            ret = 0;
            break;
        }

        schedule();

        /* see if a signal did it */
        if (signal_pending(current)) {
            ret = -ERESTARTSYS;
            break;
        }

        cprev = cnow;
    }

    current->state = TASK_RUNNING;
    remove_wait_queue(&port->delta_msr_wait, &wait);

    return ret;
}

/*
 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
 * Return: write counters to the user passed counter struct
 * NB: both 1->0 and 0->1 transitions are counted except for
 *     RI where only 0->1 is counted.
 */
static int uart_get_icount(struct tty_struct *tty,
              struct serial_icounter_struct *icount)
{
    struct uart_state *state = tty->driver_data;
    struct uart_icount cnow;
    struct uart_port *uport = state->uart_port;

    spin_lock_irq(&uport->lock);
    memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
    spin_unlock_irq(&uport->lock);

    icount->cts         = cnow.cts;
    icount->dsr         = cnow.dsr;
    icount->rng         = cnow.rng;
    icount->dcd         = cnow.dcd;
    icount->rx          = cnow.rx;
    icount->tx          = cnow.tx;
    icount->frame       = cnow.frame;
    icount->overrun     = cnow.overrun;
    icount->parity      = cnow.parity;
    icount->brk         = cnow.brk;
    icount->buf_overrun = cnow.buf_overrun;

    return 0;
}

/*
 * Called via sys_ioctl.  We can use spin_lock_irq() here.
 */
static int
uart_ioctl(struct tty_struct *tty, unsigned int cmd,
       unsigned long arg)
{
    struct uart_state *state = tty->driver_data;
    struct tty_port *port = &state->port;
    void __user *uarg = (void __user *)arg;
    int ret = -ENOIOCTLCMD;


    /*
     * These ioctls don't rely on the hardware to be present.
     */
    switch (cmd) {
    case TIOCGSERIAL:
        ret = uart_get_info_user(state, uarg);
        break;

    case TIOCSSERIAL:
        ret = uart_set_info_user(tty, state, uarg);
        break;

    case TIOCSERCONFIG:
        ret = uart_do_autoconfig(tty, state);
        break;

    case TIOCSERGWILD: /* obsolete */
    case TIOCSERSWILD: /* obsolete */
        ret = 0;
        break;
    }

    if (ret != -ENOIOCTLCMD)
        goto out;

    if (tty->flags & (1 << TTY_IO_ERROR)) {
        ret = -EIO;
        goto out;
    }

    /*
     * The following should only be used when hardware is present.
     */
    switch (cmd) {
    case TIOCMIWAIT:
        ret = uart_wait_modem_status(state, arg);
        break;
    }

    if (ret != -ENOIOCTLCMD)
        goto out;

    mutex_lock(&port->mutex);

    if (tty->flags & (1 << TTY_IO_ERROR)) {
        ret = -EIO;
        goto out_up;
    }

    /*
     * All these rely on hardware being present and need to be
     * protected against the tty being hung up.
     */
    switch (cmd) {
    case TIOCSERGETLSR: /* Get line status register */
        ret = uart_get_lsr_info(tty, state, uarg);
        break;

    default: {
        struct uart_port *uport = state->uart_port;
        if (uport->ops->ioctl)
            ret = uport->ops->ioctl(uport, cmd, arg);
        break;
    }
    }
out_up:
    mutex_unlock(&port->mutex);
out:
    return ret;
}

static void uart_set_ldisc(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *uport = state->uart_port;

    if (uport->ops->set_ldisc)
        uport->ops->set_ldisc(uport, tty->termios.c_line);
}

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


    /*
     * These are the bits that are used to setup various
     * flags in the low level driver. We can ignore the Bfoo
     * bits in c_cflag; c_[io]speed will always be set
     * appropriately by set_termios() in tty_ioctl.c
     */
#define RELEVANT_IFLAG(iflag)   ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
    if ((cflag ^ old_termios->c_cflag) == 0 &&
        tty->termios.c_ospeed == old_termios->c_ospeed &&
        tty->termios.c_ispeed == old_termios->c_ispeed &&
        RELEVANT_IFLAG(tty->termios.c_iflag ^ old_termios->c_iflag) == 0) {
        return;
    }

    uart_change_speed(tty, state, old_termios);

    /* Handle transition to B0 status */
    if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
        uart_clear_mctrl(state->uart_port, TIOCM_RTS | TIOCM_DTR);
    /* Handle transition away from B0 status */
    else if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
        unsigned int mask = TIOCM_DTR;
        if (!(cflag & CRTSCTS) ||
            !test_bit(TTY_THROTTLED, &tty->flags))
            mask |= TIOCM_RTS;
        uart_set_mctrl(state->uart_port, mask);
    }

    /* Handle turning off CRTSCTS */
    if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
        spin_lock_irqsave(&state->uart_port->lock, flags);
        tty->hw_stopped = 0;
        __uart_start(tty);
        spin_unlock_irqrestore(&state->uart_port->lock, flags);
    }
    /* Handle turning on CRTSCTS */
    else if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
        spin_lock_irqsave(&state->uart_port->lock, flags);
        if (!(state->uart_port->ops->get_mctrl(state->uart_port) & TIOCM_CTS)) {
            tty->hw_stopped = 1;
            state->uart_port->ops->stop_tx(state->uart_port);
        }
        spin_unlock_irqrestore(&state->uart_port->lock, flags);
    }
}

/*
 * In 2.4.5, calls to this will be serialized via the BKL in
 *  linux/drivers/char/tty_io.c:tty_release()
 *  linux/drivers/char/tty_io.c:do_tty_handup()
 */
static void uart_close(struct tty_struct *tty, struct file *filp)
{
    struct uart_state *state = tty->driver_data;
    struct tty_port *port;
    struct uart_port *uport;
    unsigned long flags;

    if (!state)
        return;

    uport = state->uart_port;
    port = &state->port;

    pr_debug("uart_close(%d) called\n", uport->line);

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

    /*
     * At this point, we stop accepting input.  To do this, we
     * disable the receive line status interrupts.
     */
    if (port->flags & ASYNC_INITIALIZED) {
        unsigned long flags;
        spin_lock_irqsave(&uport->lock, flags);
        uport->ops->stop_rx(uport);
        spin_unlock_irqrestore(&uport->lock, flags);
        /*
         * Before we drop DTR, make sure the UART transmitter
         * has completely drained; this is especially
         * important if there is a transmit FIFO!
         */
        uart_wait_until_sent(tty, uport->timeout);
    }

    mutex_lock(&port->mutex);
    uart_shutdown(tty, state);
    uart_flush_buffer(tty);

    tty_ldisc_flush(tty);

    tty_port_tty_set(port, NULL);
    spin_lock_irqsave(&port->lock, flags);
    tty->closing = 0;

    if (port->blocked_open) {
        spin_unlock_irqrestore(&port->lock, flags);
        if (port->close_delay)
            msleep_interruptible(
                    jiffies_to_msecs(port->close_delay));
        spin_lock_irqsave(&port->lock, flags);
    } else if (!uart_console(uport)) {
        spin_unlock_irqrestore(&port->lock, flags);
        uart_change_pm(state, 3);
        spin_lock_irqsave(&port->lock, flags);
    }

    /*
     * Wake up anyone trying to open this port.
     */
    clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
    clear_bit(ASYNCB_CLOSING, &port->flags);
    spin_unlock_irqrestore(&port->lock, flags);
    wake_up_interruptible(&port->open_wait);
    wake_up_interruptible(&port->close_wait);

    mutex_unlock(&port->mutex);
}

static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
{
    struct uart_state *state = tty->driver_data;
    struct uart_port *port = state->uart_port;
    unsigned long char_time, expire;

    if (port->type == PORT_UNKNOWN || port->fifosize == 0)
        return;

    /*
     * 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 = (port->timeout - HZ/50) / port->fifosize;
    char_time = char_time / 5;
    if (char_time == 0)
        char_time = 1;
    if (timeout && timeout < char_time)
        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 port->timeout, this is probably due to a
     * UART bug of some kind.  So, we clamp the timeout parameter at
     * 2*port->timeout.
     */
    if (timeout == 0 || timeout > 2 * port->timeout)
        timeout = 2 * port->timeout;

    expire = jiffies + timeout;

    pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
        port->line, jiffies, expire);

    /*
     * Check whether the transmitter is empty every 'char_time'.
     * 'timeout' / 'expire' give us the maximum amount of time
     * we wait.
     */
    while (!port->ops->tx_empty(port)) {
        msleep_interruptible(jiffies_to_msecs(char_time));
        if (signal_pending(current))
            break;
        if (time_after(jiffies, expire))
            break;
    }
}

/*
 * This is called with the BKL held in
 *  linux/drivers/char/tty_io.c:do_tty_hangup()
 * We're called from the eventd thread, so we can sleep for
 * a _short_ time only.
 */
static void uart_hangup(struct tty_struct *tty)
{
    struct uart_state *state = tty->driver_data;
    struct tty_port *port = &state->port;
    unsigned long flags;

    pr_debug("uart_hangup(%d)\n", state->uart_port->line);

    mutex_lock(&port->mutex);
    if (port->flags & ASYNC_NORMAL_ACTIVE) {
        uart_flush_buffer(tty);
        uart_shutdown(tty, state);
        spin_lock_irqsave(&port->lock, flags);
        port->count = 0;
        clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
        spin_unlock_irqrestore(&port->lock, flags);
        tty_port_tty_set(port, NULL);
        wake_up_interruptible(&port->open_wait);
        wake_up_interruptible(&port->delta_msr_wait);
    }
    mutex_unlock(&port->mutex);
}

static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
{
    return 0;
}

static void uart_port_shutdown(struct tty_port *port)
{
    struct uart_state *state = container_of(port, struct uart_state, port);
    struct uart_port *uport = state->uart_port;

    /*
     * clear delta_msr_wait queue to avoid mem leaks: we may free
     * the irq here so the queue might never be woken up.  Note
     * that we won't end up waiting on delta_msr_wait again since
     * any outstanding file descriptors should be pointing at
     * hung_up_tty_fops now.
     */
    wake_up_interruptible(&port->delta_msr_wait);

    /*
     * Free the IRQ and disable the port.
     */
    uport->ops->shutdown(uport);

    /*
     * Ensure that the IRQ handler isn't running on another CPU.
     */
    synchronize_irq(uport->irq);
}

static int uart_carrier_raised(struct tty_port *port)
{
    struct uart_state *state = container_of(port, struct uart_state, port);
    struct uart_port *uport = state->uart_port;
    int mctrl;
    spin_lock_irq(&uport->lock);
    uport->ops->enable_ms(uport);
    mctrl = uport->ops->get_mctrl(uport);
    spin_unlock_irq(&uport->lock);
    if (mctrl & TIOCM_CAR)
        return 1;
    return 0;
}

static void uart_dtr_rts(struct tty_port *port, int onoff)
{
    struct uart_state *state = container_of(port, struct uart_state, port);
    struct uart_port *uport = state->uart_port;

    if (onoff)
        uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
    else
        uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
}

/*
 * calls to uart_open are serialised by the BKL in
 *   fs/char_dev.c:chrdev_open()
 * Note that if this fails, then uart_close() _will_ be called.
 *
 * In time, we want to scrap the "opening nonpresent ports"
 * behaviour and implement an alternative way for setserial
 * to set base addresses/ports/types.  This will allow us to
 * get rid of a certain amount of extra tests.
 */
static int uart_open(struct tty_struct *tty, struct file *filp)
{
    struct uart_driver *drv = (struct uart_driver *)tty->driver->driver_state;
    int retval, line = tty->index;
    struct uart_state *state = drv->state + line;
    struct tty_port *port = &state->port;

    pr_debug("uart_open(%d) called\n", line);

    /*
     * We take the semaphore here to guarantee that we won't be re-entered
     * while allocating the state structure, or while we request any IRQs
     * that the driver may need.  This also has the nice side-effect that
     * it delays the action of uart_hangup, so we can guarantee that
     * state->port.tty will always contain something reasonable.
     */
    if (mutex_lock_interruptible(&port->mutex)) {
        retval = -ERESTARTSYS;
        goto end;
    }

    port->count++;
    if (!state->uart_port || state->uart_port->flags & UPF_DEAD) {
        retval = -ENXIO;
        goto err_dec_count;
    }

    /*
     * Once we set tty->driver_data here, we are guaranteed that
     * uart_close() will decrement the driver module use count.
     * Any failures from here onwards should not touch the count.
     */
    tty->driver_data = state;
    state->uart_port->state = state;
    tty->low_latency = (state->uart_port->flags & UPF_LOW_LATENCY) ? 1 : 0;
    tty_port_tty_set(port, tty);

    /*
     * If the port is in the middle of closing, bail out now.
     */
    if (tty_hung_up_p(filp)) {
        retval = -EAGAIN;
        goto err_dec_count;
    }

    /*
     * Make sure the device is in D0 state.
     */
    if (port->count == 1)
        uart_change_pm(state, 0);

    /*
     * Start up the serial port.
     */
    retval = uart_startup(tty, state, 0);

    /*
     * If we succeeded, wait until the port is ready.
     */
    mutex_unlock(&port->mutex);
    if (retval == 0)
        retval = tty_port_block_til_ready(port, tty, filp);

end:
    return retval;
err_dec_count:
    port->count--;
    mutex_unlock(&port->mutex);
    goto end;
}

static const char *uart_type(struct uart_port *port)
{
    const char *str = NULL;

    if (port->ops->type)
        str = port->ops->type(port);

    if (!str)
        str = "unknown";

    return str;
}

#ifdef CONFIG_PROC_FS

static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
{
    struct uart_state *state = drv->state + i;
    struct tty_port *port = &state->port;
    int pm_state;
    struct uart_port *uport = state->uart_port;
    char stat_buf[32];
    unsigned int status;
    int mmio;

    if (!uport)
        return;

    mmio = uport->iotype >= UPIO_MEM;
    seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
            uport->line, uart_type(uport),
            mmio ? "mmio:0x" : "port:",
            mmio ? (unsigned long long)uport->mapbase
                 : (unsigned long long)uport->iobase,
            uport->irq);

    if (uport->type == PORT_UNKNOWN) {
        seq_putc(m, '\n');
        return;
    }

    if (capable(CAP_SYS_ADMIN)) {
        mutex_lock(&port->mutex);
        pm_state = state->pm_state;
        if (pm_state)
            uart_change_pm(state, 0);
        spin_lock_irq(&uport->lock);
        status = uport->ops->get_mctrl(uport);
        spin_unlock_irq(&uport->lock);
        if (pm_state)
            uart_change_pm(state, pm_state);
        mutex_unlock(&port->mutex);

        seq_printf(m, " tx:%d rx:%d",
                uport->icount.tx, uport->icount.rx);
        if (uport->icount.frame)
            seq_printf(m, " fe:%d",
                uport->icount.frame);
        if (uport->icount.parity)
            seq_printf(m, " pe:%d",
                uport->icount.parity);
        if (uport->icount.brk)
            seq_printf(m, " brk:%d",
                uport->icount.brk);
        if (uport->icount.overrun)
            seq_printf(m, " oe:%d",
                uport->icount.overrun);

#define INFOBIT(bit, str) \
    if (uport->mctrl & (bit)) \
        strncat(stat_buf, (str), sizeof(stat_buf) - \
            strlen(stat_buf) - 2)
#define STATBIT(bit, str) \
    if (status & (bit)) \
        strncat(stat_buf, (str), sizeof(stat_buf) - \
               strlen(stat_buf) - 2)

        stat_buf[0] = '\0';
        stat_buf[1] = '\0';
        INFOBIT(TIOCM_RTS, "|RTS");
        STATBIT(TIOCM_CTS, "|CTS");
        INFOBIT(TIOCM_DTR, "|DTR");
        STATBIT(TIOCM_DSR, "|DSR");
        STATBIT(TIOCM_CAR, "|CD");
        STATBIT(TIOCM_RNG, "|RI");
        if (stat_buf[0])
            stat_buf[0] = ' ';

        seq_puts(m, stat_buf);
    }
    seq_putc(m, '\n');
#undef STATBIT
#undef INFOBIT
}

static int uart_proc_show(struct seq_file *m, void *v)
{
    struct tty_driver *ttydrv = m->private;
    struct uart_driver *drv = ttydrv->driver_state;
    int i;

    seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n",
            "", "", "");
    for (i = 0; i < drv->nr; i++)
        uart_line_info(m, drv, i);
    return 0;
}

static int uart_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, uart_proc_show, PDE(inode)->data);
}

static const struct file_operations uart_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = uart_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
};
#endif

#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
/*
 *  uart_console_write - write a console message to a serial port
 *  @port: the port to write the message
 *  @s: array of characters
 *  @count: number of characters in string to write
 *  @write: function to write character to port
 */
void uart_console_write(struct uart_port *port, const char *s,
            unsigned int count,
            void (*putchar)(struct uart_port *, int))
{
    unsigned int i;

    for (i = 0; i < count; i++, s++) {
        if (*s == '\n')
            putchar(port, '\r');
        putchar(port, *s);
    }
}
EXPORT_SYMBOL_GPL(uart_console_write);

/*
 *  Check whether an invalid uart number has been specified, and
 *  if so, search for the first available port that does have
 *  console support.
 */
struct uart_port * __init
uart_get_console(struct uart_port *ports, int nr, struct console *co)
{
    int idx = co->index;

    if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
                     ports[idx].membase == NULL))
        for (idx = 0; idx < nr; idx++)
            if (ports[idx].iobase != 0 ||
                ports[idx].membase != NULL)
                break;

    co->index = idx;

    return ports + idx;
}

void
uart_parse_options(char *options, int *baud, int *parity, int *bits, int *flow)
{
    char *s = options;

    *baud = simple_strtoul(s, NULL, 10);
    while (*s >= '0' && *s <= '9')
        s++;
    if (*s)
        *parity = *s++;
    if (*s)
        *bits = *s++ - '0';
    if (*s)
        *flow = *s;
}
EXPORT_SYMBOL_GPL(uart_parse_options);

struct baud_rates {
    unsigned int rate;
    unsigned int cflag;
};

static const struct baud_rates baud_rates[] = {
    { 921600, B921600 },
    { 460800, B460800 },
    { 230400, B230400 },
    { 115200, B115200 },
    {  57600, B57600  },
    {  38400, B38400  },
    {  19200, B19200  },
    {   9600, B9600   },
    {   4800, B4800   },
    {   2400, B2400   },
    {   1200, B1200   },
    {      0, B38400  }
};

int
uart_set_options(struct uart_port *port, struct console *co,
         int baud, int parity, int bits, int flow)
{
    struct ktermios termios;
    static struct ktermios dummy;
    int i;

    /*
     * Ensure that the serial console lock is initialised
     * early.
     */
    spin_lock_init(&port->lock);
    lockdep_set_class(&port->lock, &port_lock_key);

    memset(&termios, 0, sizeof(struct ktermios));

    termios.c_cflag = CREAD | HUPCL | CLOCAL;

    /*
     * Construct a cflag setting.
     */
    for (i = 0; baud_rates[i].rate; i++)
        if (baud_rates[i].rate <= baud)
            break;

    termios.c_cflag |= baud_rates[i].cflag;

    if (bits == 7)
        termios.c_cflag |= CS7;
    else
        termios.c_cflag |= CS8;

    switch (parity) {
    case 'o': case 'O':
        termios.c_cflag |= PARODD;
        /*fall through*/
    case 'e': case 'E':
        termios.c_cflag |= PARENB;
        break;
    }

    if (flow == 'r')
        termios.c_cflag |= CRTSCTS;

    /*
     * some uarts on other side don't support no flow control.
     * So we set * DTR in host uart to make them happy
     */
    port->mctrl |= TIOCM_DTR;

    port->ops->set_termios(port, &termios, &dummy);
    /*
     * Allow the setting of the UART parameters with a NULL console
     * too:
     */
    if (co)
        co->cflag = termios.c_cflag;

    return 0;
}
EXPORT_SYMBOL_GPL(uart_set_options);
#endif /* CONFIG_SERIAL_CORE_CONSOLE */

static void uart_change_pm(struct uart_state *state, int pm_state)
{
    struct uart_port *port = state->uart_port;

    if (state->pm_state != pm_state) {
        if (port->ops->pm)
            port->ops->pm(port, pm_state, state->pm_state);
        state->pm_state = pm_state;
    }
}

struct uart_match {
    struct uart_port *port;
    struct uart_driver *driver;
};

static int serial_match_port(struct device *dev, void *data)
{
    struct uart_match *match = data;
    struct tty_driver *tty_drv = match->driver->tty_driver;
    dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
        match->port->line;

    return dev->devt == devt; /* Actually, only one tty per port */
}

int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
{
    struct uart_state *state = drv->state + uport->line;
    struct tty_port *port = &state->port;
    struct device *tty_dev;
    struct uart_match match = {uport, drv};

    mutex_lock(&port->mutex);

    tty_dev = device_find_child(uport->dev, &match, serial_match_port);
    if (device_may_wakeup(tty_dev)) {
        if (!enable_irq_wake(uport->irq))
            uport->irq_wake = 1;
        put_device(tty_dev);
        mutex_unlock(&port->mutex);
        return 0;
    }
    if (console_suspend_enabled || !uart_console(uport))
        uport->suspended = 1;

    if (port->flags & ASYNC_INITIALIZED) {
        const struct uart_ops *ops = uport->ops;
        int tries;

        if (console_suspend_enabled || !uart_console(uport)) {
            set_bit(ASYNCB_SUSPENDED, &port->flags);
            clear_bit(ASYNCB_INITIALIZED, &port->flags);

            spin_lock_irq(&uport->lock);
            ops->stop_tx(uport);
            ops->set_mctrl(uport, 0);
            ops->stop_rx(uport);
            spin_unlock_irq(&uport->lock);
        }

        /*
         * Wait for the transmitter to empty.
         */
        for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
            msleep(10);
        if (!tries)
            printk(KERN_ERR "%s%s%s%d: Unable to drain "
                    "transmitter\n",
                   uport->dev ? dev_name(uport->dev) : "",
                   uport->dev ? ": " : "",
                   drv->dev_name,
                   drv->tty_driver->name_base + uport->line);

        if (console_suspend_enabled || !uart_console(uport))
            ops->shutdown(uport);
    }

    /*
     * Disable the console device before suspending.
     */
    if (console_suspend_enabled && uart_console(uport))
        console_stop(uport->cons);

    if (console_suspend_enabled || !uart_console(uport))
        uart_change_pm(state, 3);

    mutex_unlock(&port->mutex);

    return 0;
}

int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
{
    struct uart_state *state = drv->state + uport->line;
    struct tty_port *port = &state->port;
    struct device *tty_dev;
    struct uart_match match = {uport, drv};
    struct ktermios termios;

    mutex_lock(&port->mutex);

    tty_dev = device_find_child(uport->dev, &match, serial_match_port);
    if (!uport->suspended && device_may_wakeup(tty_dev)) {
        if (uport->irq_wake) {
            disable_irq_wake(uport->irq);
            uport->irq_wake = 0;
        }
        mutex_unlock(&port->mutex);
        return 0;
    }
    uport->suspended = 0;

    /*
     * Re-enable the console device after suspending.
     */
    if (uart_console(uport)) {
        /*
         * First try to use the console cflag setting.
         */
        memset(&termios, 0, sizeof(struct ktermios));
        termios.c_cflag = uport->cons->cflag;

        /*
         * If that's unset, use the tty termios setting.
         */
        if (port->tty && termios.c_cflag == 0)
            termios = port->tty->termios;

        if (console_suspend_enabled)
            uart_change_pm(state, 0);
        uport->ops->set_termios(uport, &termios, NULL);
        if (console_suspend_enabled)
            console_start(uport->cons);
    }

    if (port->flags & ASYNC_SUSPENDED) {
        const struct uart_ops *ops = uport->ops;
        int ret;

        uart_change_pm(state, 0);
        spin_lock_irq(&uport->lock);
        ops->set_mctrl(uport, 0);
        spin_unlock_irq(&uport->lock);
        if (console_suspend_enabled || !uart_console(uport)) {
            /* Protected by port mutex for now */
            struct tty_struct *tty = port->tty;
            ret = ops->startup(uport);
            if (ret == 0) {
                if (tty)
                    uart_change_speed(tty, state, NULL);
                spin_lock_irq(&uport->lock);
                ops->set_mctrl(uport, uport->mctrl);
                ops->start_tx(uport);
                spin_unlock_irq(&uport->lock);
                set_bit(ASYNCB_INITIALIZED, &port->flags);
            } else {
                /*
                 * Failed to resume - maybe hardware went away?
                 * Clear the "initialized" flag so we won't try
                 * to call the low level drivers shutdown method.
                 */
                uart_shutdown(tty, state);
            }
        }

        clear_bit(ASYNCB_SUSPENDED, &port->flags);
    }

    mutex_unlock(&port->mutex);

    return 0;
}

static inline void
uart_report_port(struct uart_driver *drv, struct uart_port *port)
{
    char address[64];

    switch (port->iotype) {
    case UPIO_PORT:
        snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
        break;
    case UPIO_HUB6:
        snprintf(address, sizeof(address),
             "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
        break;
    case UPIO_MEM:
    case UPIO_MEM32:
    case UPIO_AU:
    case UPIO_TSI:
        snprintf(address, sizeof(address),
             "MMIO 0x%llx", (unsigned long long)port->mapbase);
        break;
    default:
        strlcpy(address, "*unknown*", sizeof(address));
        break;
    }

    printk(KERN_INFO "%s%s%s%d at %s (irq = %d) is a %s\n",
           port->dev ? dev_name(port->dev) : "",
           port->dev ? ": " : "",
           drv->dev_name,
           drv->tty_driver->name_base + port->line,
           address, port->irq, uart_type(port));
}

static void
uart_configure_port(struct uart_driver *drv, struct uart_state *state,
            struct uart_port *port)
{
    unsigned int flags;

    /*
     * If there isn't a port here, don't do anything further.
     */
    if (!port->iobase && !port->mapbase && !port->membase)
        return;

    /*
     * Now do the auto configuration stuff.  Note that config_port
     * is expected to claim the resources and map the port for us.
     */
    flags = 0;
    if (port->flags & UPF_AUTO_IRQ)
        flags |= UART_CONFIG_IRQ;
    if (port->flags & UPF_BOOT_AUTOCONF) {
        if (!(port->flags & UPF_FIXED_TYPE)) {
            port->type = PORT_UNKNOWN;
            flags |= UART_CONFIG_TYPE;
        }
        port->ops->config_port(port, flags);
    }

    if (port->type != PORT_UNKNOWN) {
        unsigned long flags;

        uart_report_port(drv, port);

        /* Power up port for set_mctrl() */
        uart_change_pm(state, 0);

        /*
         * Ensure that the modem control lines are de-activated.
         * keep the DTR setting that is set in uart_set_options()
         * We probably don't need a spinlock around this, but
         */
        spin_lock_irqsave(&port->lock, flags);
        port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
        spin_unlock_irqrestore(&port->lock, flags);

        /*
         * If this driver supports console, and it hasn't been
         * successfully registered yet, try to re-register it.
         * It may be that the port was not available.
         */
        if (port->cons && !(port->cons->flags & CON_ENABLED))
            register_console(port->cons);

        /*
         * Power down all ports by default, except the
         * console if we have one.
         */
        if (!uart_console(port))
            uart_change_pm(state, 3);
    }
}

#ifdef CONFIG_CONSOLE_POLL

static int uart_poll_init(struct tty_driver *driver, int line, char *options)
{
    struct uart_driver *drv = driver->driver_state;
    struct uart_state *state = drv->state + line;
    struct uart_port *port;
    int baud = 9600;
    int bits = 8;
    int parity = 'n';
    int flow = 'n';
    int ret;

    if (!state || !state->uart_port)
        return -1;

    port = state->uart_port;
    if (!(port->ops->poll_get_char && port->ops->poll_put_char))
        return -1;

    if (port->ops->poll_init) {
        struct tty_port *tport = &state->port;

        ret = 0;
        mutex_lock(&tport->mutex);
        /*
         * We don't set ASYNCB_INITIALIZED as we only initialized the
         * hw, e.g. state->xmit is still uninitialized.
         */
        if (!test_bit(ASYNCB_INITIALIZED, &tport->flags))
            ret = port->ops->poll_init(port);
        mutex_unlock(&tport->mutex);
        if (ret)
            return ret;
    }

    if (options) {
        uart_parse_options(options, &baud, &parity, &bits, &flow);
        return uart_set_options(port, NULL, baud, parity, bits, flow);
    }

    return 0;
}

static int uart_poll_get_char(struct tty_driver *driver, int line)
{
    struct uart_driver *drv = driver->driver_state;
    struct uart_state *state = drv->state + line;
    struct uart_port *port;

    if (!state || !state->uart_port)
        return -1;

    port = state->uart_port;
    return port->ops->poll_get_char(port);
}

static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
{
    struct uart_driver *drv = driver->driver_state;
    struct uart_state *state = drv->state + line;
    struct uart_port *port;

    if (!state || !state->uart_port)
        return;

    port = state->uart_port;
    port->ops->poll_put_char(port, ch);
}
#endif

static const struct tty_operations uart_ops = {
    .open       = uart_open,
    .close      = uart_close,
    .write      = uart_write,
    .put_char   = uart_put_char,
    .flush_chars    = uart_flush_chars,
    .write_room = uart_write_room,
    .chars_in_buffer= uart_chars_in_buffer,
    .flush_buffer   = uart_flush_buffer,
    .ioctl      = uart_ioctl,
    .throttle   = uart_throttle,
    .unthrottle = uart_unthrottle,
    .send_xchar = uart_send_xchar,
    .set_termios    = uart_set_termios,
    .set_ldisc  = uart_set_ldisc,
    .stop       = uart_stop,
    .start      = uart_start,
    .hangup     = uart_hangup,
    .break_ctl  = uart_break_ctl,
    .wait_until_sent= uart_wait_until_sent,
#ifdef CONFIG_PROC_FS
    .proc_fops  = &uart_proc_fops,
#endif
    .tiocmget   = uart_tiocmget,
    .tiocmset   = uart_tiocmset,
    .get_icount = uart_get_icount,
#ifdef CONFIG_CONSOLE_POLL
    .poll_init  = uart_poll_init,
    .poll_get_char  = uart_poll_get_char,
    .poll_put_char  = uart_poll_put_char,
#endif
};

static const struct tty_port_operations uart_port_ops = {
    .activate   = uart_port_activate,
    .shutdown   = uart_port_shutdown,
    .carrier_raised = uart_carrier_raised,
    .dtr_rts    = uart_dtr_rts,
};

int uart_register_driver(struct uart_driver *drv)
{
    struct tty_driver *normal;
    int i, retval;

    BUG_ON(drv->state);

    /*
     * Maybe we should be using a slab cache for this, especially if
     * we have a large number of ports to handle.
     */
    drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
    if (!drv->state)
        goto out;

    normal = alloc_tty_driver(drv->nr);
    if (!normal)
        goto out_kfree;

    drv->tty_driver = normal;

    normal->driver_name = drv->driver_name;
    normal->name        = drv->dev_name;
    normal->major       = drv->major;
    normal->minor_start = drv->minor;
    normal->type        = TTY_DRIVER_TYPE_SERIAL;
    normal->subtype     = SERIAL_TYPE_NORMAL;
    normal->init_termios    = tty_std_termios;
    normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
    normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
    normal->flags       = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
    normal->driver_state    = drv;
    tty_set_operations(normal, &uart_ops);

    /*
     * Initialise the UART state(s).
     */
    for (i = 0; i < drv->nr; i++) {
        struct uart_state *state = drv->state + i;
        struct tty_port *port = &state->port;

        tty_port_init(port);
        port->ops = &uart_port_ops;
        port->close_delay     = HZ / 2; /* .5 seconds */
        port->closing_wait    = 30 * HZ;/* 30 seconds */
    }

    retval = tty_register_driver(normal);
    if (retval >= 0)
        return retval;

    put_tty_driver(normal);
out_kfree:
    kfree(drv->state);
out:
    return -ENOMEM;
}

void uart_unregister_driver(struct uart_driver *drv)
{
    struct tty_driver *p = drv->tty_driver;
    tty_unregister_driver(p);
    put_tty_driver(p);
    kfree(drv->state);
    drv->state = NULL;
    drv->tty_driver = NULL;
}

struct tty_driver *uart_console_device(struct console *co, int *index)
{
    struct uart_driver *p = co->data;
    *index = co->index;
    return p->tty_driver;
}

static ssize_t uart_get_attr_uartclk(struct device *dev,
    struct device_attribute *attr, char *buf)
{
    int ret;
    struct tty_port *port = dev_get_drvdata(dev);
    struct uart_state *state = container_of(port, struct uart_state, port);

    mutex_lock(&state->port.mutex);
    ret = snprintf(buf, PAGE_SIZE, "%d\n", state->uart_port->uartclk);
    mutex_unlock(&state->port.mutex);

    return ret;
}

static DEVICE_ATTR(uartclk, S_IRUSR | S_IRGRP, uart_get_attr_uartclk, NULL);

static struct attribute *tty_dev_attrs[] = {
    &dev_attr_uartclk.attr,
    NULL,
    };

static const struct attribute_group tty_dev_attr_group = {
    .attrs = tty_dev_attrs,
    };

static const struct attribute_group *tty_dev_attr_groups[] = {
    &tty_dev_attr_group,
    NULL
    };

int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
{
    struct uart_state *state;
    struct tty_port *port;
    int ret = 0;
    struct device *tty_dev;

    BUG_ON(in_interrupt());

    if (uport->line >= drv->nr)
        return -EINVAL;

    state = drv->state + uport->line;
    port = &state->port;

    mutex_lock(&port_mutex);
    mutex_lock(&port->mutex);
    if (state->uart_port) {
        ret = -EINVAL;
        goto out;
    }

    state->uart_port = uport;
    state->pm_state = -1;

    uport->cons = drv->cons;
    uport->state = state;

    /*
     * If this port is a console, then the spinlock is already
     * initialised.
     */
    if (!(uart_console(uport) && (uport->cons->flags & CON_ENABLED))) {
        spin_lock_init(&uport->lock);
        lockdep_set_class(&uport->lock, &port_lock_key);
    }

    uart_configure_port(drv, state, uport);

    /*
     * Register the port whether it's detected or not.  This allows
     * setserial to be used to alter this ports parameters.
     */
    tty_dev = tty_port_register_device_attr(port, drv->tty_driver,
            uport->line, uport->dev, port, tty_dev_attr_groups);
    if (likely(!IS_ERR(tty_dev))) {
        device_set_wakeup_capable(tty_dev, 1);
    } else {
        printk(KERN_ERR "Cannot register tty device on line %d\n",
               uport->line);
    }

    /*
     * Ensure UPF_DEAD is not set.
     */
    uport->flags &= ~UPF_DEAD;

 out:
    mutex_unlock(&port->mutex);
    mutex_unlock(&port_mutex);

    return ret;
}

int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
{
    struct uart_state *state = drv->state + uport->line;
    struct tty_port *port = &state->port;

    BUG_ON(in_interrupt());

    if (state->uart_port != uport)
        printk(KERN_ALERT "Removing wrong port: %p != %p\n",
            state->uart_port, uport);

    mutex_lock(&port_mutex);

    /*
     * Mark the port "dead" - this prevents any opens from
     * succeeding while we shut down the port.
     */
    mutex_lock(&port->mutex);
    uport->flags |= UPF_DEAD;
    mutex_unlock(&port->mutex);

    /*
     * Remove the devices from the tty layer
     */
    tty_unregister_device(drv->tty_driver, uport->line);

    if (port->tty)
        tty_vhangup(port->tty);

    /*
     * Free the port IO and memory resources, if any.
     */
    if (uport->type != PORT_UNKNOWN)
        uport->ops->release_port(uport);

    /*
     * Indicate that there isn't a port here anymore.
     */
    uport->type = PORT_UNKNOWN;

    state->uart_port = NULL;
    mutex_unlock(&port_mutex);

    return 0;
}

/*
 *  Are the two ports equivalent?
 */
int uart_match_port(struct uart_port *port1, struct uart_port *port2)
{
    if (port1->iotype != port2->iotype)
        return 0;

    switch (port1->iotype) {
    case UPIO_PORT:
        return (port1->iobase == port2->iobase);
    case UPIO_HUB6:
        return (port1->iobase == port2->iobase) &&
               (port1->hub6   == port2->hub6);
    case UPIO_MEM:
    case UPIO_MEM32:
    case UPIO_AU:
    case UPIO_TSI:
        return (port1->mapbase == port2->mapbase);
    }
    return 0;
}
EXPORT_SYMBOL(uart_match_port);

void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
{
    struct uart_state *state = uport->state;
    struct tty_port *port = &state->port;
    struct tty_ldisc *ld = NULL;
    struct pps_event_time ts;
    struct tty_struct *tty = port->tty;

    if (tty)
            ld = tty_ldisc_ref(tty);
    if (ld && ld->ops->dcd_change)
        pps_get_ts(&ts);

    uport->icount.dcd++;
#ifdef CONFIG_HARD_PPS
    if ((uport->flags & UPF_HARDPPS_CD) && status)
        hardpps();
#endif

    if (port->flags & ASYNC_CHECK_CD) {
        if (status)
            wake_up_interruptible(&port->open_wait);
        else if (tty)
            tty_hangup(tty);
    }

    if (ld && ld->ops->dcd_change)
        ld->ops->dcd_change(tty, status, &ts);
    if (ld)
        tty_ldisc_deref(ld);
}
EXPORT_SYMBOL_GPL(uart_handle_dcd_change);

void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
{
    struct tty_port *port = &uport->state->port;
    struct tty_struct *tty = port->tty;

    uport->icount.cts++;

    if (tty_port_cts_enabled(port)) {
        if (tty->hw_stopped) {
            if (status) {
                tty->hw_stopped = 0;
                uport->ops->start_tx(uport);
                uart_write_wakeup(uport);
            }
        } else {
            if (!status) {
                tty->hw_stopped = 1;
                uport->ops->stop_tx(uport);
            }
        }
    }
}
EXPORT_SYMBOL_GPL(uart_handle_cts_change);

void uart_insert_char(struct uart_port *port, unsigned int status,
         unsigned int overrun, unsigned int ch, unsigned int flag)
{
    struct tty_struct *tty = port->state->port.tty;

    if ((status & port->ignore_status_mask & ~overrun) == 0)
        if (tty_insert_flip_char(tty, ch, flag) == 0)
            ++port->icount.buf_overrun;

    /*
     * Overrun is special.  Since it's reported immediately,
     * it doesn't affect the current character.
     */
    if (status & ~port->ignore_status_mask & overrun)
        if (tty_insert_flip_char(tty, 0, TTY_OVERRUN) == 0)
            ++port->icount.buf_overrun;
}
EXPORT_SYMBOL_GPL(uart_insert_char);

EXPORT_SYMBOL(uart_write_wakeup);
EXPORT_SYMBOL(uart_register_driver);
EXPORT_SYMBOL(uart_unregister_driver);
EXPORT_SYMBOL(uart_suspend_port);
EXPORT_SYMBOL(uart_resume_port);
EXPORT_SYMBOL(uart_add_one_port);
EXPORT_SYMBOL(uart_remove_one_port);

MODULE_DESCRIPTION("Serial driver core");
MODULE_LICENSE("GPL");