serial_sicc.c

底层驱动开发

        result &= TIOCSER_TEMT;

    return put_user(result, value);
}

static int get_modem_info(struct SICC_info *info, unsigned int *value)
{
    unsigned int result = info->mctrl;

    return put_user(result, value);
}

static int set_modem_info(struct SICC_info *info, unsigned int cmd,
              unsigned int *value)
{
    unsigned int arg, old;
    unsigned long flags;

    if (get_user(arg, value))
        return -EFAULT;

    old = info->mctrl;
    switch (cmd) {
    case TIOCMBIS:
        info->mctrl |= arg;
        break;

    case TIOCMBIC:
        info->mctrl &= ~arg;
        break;

    case TIOCMSET:
        info->mctrl = arg;
        break;

    default:
        return -EINVAL;
    }
    /* disable interrupts while setting modem control lines */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    if (old != info->mctrl)
        info->port->set_mctrl(info->port, info->mctrl);
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    return 0;
}

static void siccuart_break_ctl(struct tty_struct *tty, int break_state)
{
    struct SICC_info *info = tty->driver_data;
    unsigned long flags;
    unsigned int lcr_h;


    /* disable interrupts while setting break state */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    lcr_h = readb(info->port + BL_SICC_LSR);
    if (break_state == -1)
        lcr_h |=  _LSR_LB_MASK;
    else
        lcr_h &= ~_LSR_LB_MASK;
    writeb(lcr_h, info->port + BL_SICC_LSRS);
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
}

static int siccuart_ioctl(struct tty_struct *tty, struct file *file,
               unsigned int cmd, unsigned long arg)
{
    struct SICC_info *info = tty->driver_data;
    struct SICC_icount cnow;
    struct serial_icounter_struct icount;
    unsigned long flags;

    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 TIOCMGET:
            return get_modem_info(info, (unsigned int *)arg);
        case TIOCMBIS:
        case TIOCMBIC:
        case TIOCMSET:
            return set_modem_info(info, cmd, (unsigned int *)arg);
        case TIOCGSERIAL:
            return get_serial_info(info,
                           (struct serial_struct *)arg);
        case TIOCSSERIAL:
            return set_serial_info(info,
                           (struct serial_struct *)arg);
        case TIOCSERGETLSR: /* Get line status register */
            return get_lsr_info(info, (unsigned int *)arg);
        /*
         * 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:
            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:
            /* disable interrupts while getting interrupt count */
            spin_lock_irqsave(&info->state->sicc_lock,flags);
            cnow = info->state->icount;
            spin_unlock_irqrestore(&info->state->sicc_lock,flags);
            icount.cts = cnow.cts;
            icount.dsr = cnow.dsr;
            icount.rng = cnow.rng;
            icount.dcd = cnow.dcd;
            icount.rx  = cnow.rx;
            icount.tx  = cnow.tx;
            icount.frame = cnow.frame;
            icount.overrun = cnow.overrun;
            icount.parity = cnow.parity;
            icount.brk = cnow.brk;
            icount.buf_overrun = cnow.buf_overrun;

            return copy_to_user((void *)arg, &icount, sizeof(icount))
                    ? -EFAULT : 0;

        default:
            return -ENOIOCTLCMD;
    }
    return 0;
}

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

    if ((cflag ^ old_termios->c_cflag) == 0 &&
        RELEVENT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0)
        return;

    siccuart_change_speed(info, old_termios);

    /* Handle transition to B0 status */
    if ((old_termios->c_cflag & CBAUD) &&
        !(cflag & CBAUD)) {
        /* disable interrupts while setting break state */
        spin_lock_irqsave(&info->state->sicc_lock,flags);
        info->mctrl &= ~(TIOCM_RTS | TIOCM_DTR);
        info->port->set_mctrl(info->port, info->mctrl);
        spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    }

    /* Handle transition away from B0 status */
    if (!(old_termios->c_cflag & CBAUD) &&
        (cflag & CBAUD)) {
        /* disable interrupts while setting break state */
        spin_lock_irqsave(&info->state->sicc_lock,flags);
        info->mctrl |= TIOCM_DTR;
        if (!(cflag & CRTSCTS) ||
            !test_bit(TTY_THROTTLED, &tty->flags))
            info->mctrl |= TIOCM_RTS;
        info->port->set_mctrl(info->port, info->mctrl);
        spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    }

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

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

static void siccuart_close(struct tty_struct *tty, struct file *filp)
{
    struct SICC_info *info = tty->driver_data;
    struct SICC_state *state;
    unsigned long flags;

    if (!info)
        return;

    state = info->state;

    //pr_debug("siccuart_close() called\n");

    /* lock tty->driver_data while closing port */
    spin_lock_irqsave(&info->state->sicc_lock,flags);

    if (tty_hung_up_p(filp)) {
        goto quick_close;
    }

    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("siccuart_close: bad serial port count; tty->count is 1, state->count is %d\n", state->count);
        state->count = 1;
    }
    if (--state->count < 0) {
        printk("rs_close: bad serial port count for %s: %d\n", tty->name, state->count);
        state->count = 0;
    }
    if (state->count) {
        goto quick_close;
    }
    info->flags |= ASYNC_CLOSING;
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    /*
     * Now we wait for the transmit buffer to clear; and we notify
     * the line discipline to only process XON/XOFF characters.
     */
    tty->closing = 1;
    if (info->state->closing_wait != ASYNC_CLOSING_WAIT_NONE)
        tty_wait_until_sent(tty, info->state->closing_wait);
    /*
     * At this point, we stop accepting input.  To do this, we
     * disable the receive line status interrupts.
     */
    if (info->flags & ASYNC_INITIALIZED) {
        siccuart_disable_rx_interrupt(info);
        /*
         * Before we drop DTR, make sure the UART transmitter
         * has completely drained; this is especially
         * important if there is a transmit FIFO!
         */
        siccuart_wait_until_sent(tty, info->timeout);
    }
    siccuart_shutdown(info);
    if (tty->driver->flush_buffer)
        tty->driver->flush_buffer(tty);
    if (tty->ldisc.flush_buffer)
        tty->ldisc.flush_buffer(tty);
    tty->closing = 0;
    info->event = 0;
    info->tty = NULL;
    if (info->blocked_open) {
        if (info->state->close_delay) {
            set_current_state(TASK_INTERRUPTIBLE);
            schedule_timeout(info->state->close_delay);
        }
        wake_up_interruptible(&info->open_wait);
    }
    info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING);
    wake_up_interruptible(&info->close_wait);
    return;

quick_close:
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    return;
}

static void siccuart_wait_until_sent(struct tty_struct *tty, int timeout)
{
    struct SICC_info *info = (struct SICC_info *) tty->driver_data;
    unsigned long char_time, expire;

    if (info->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 = (info->timeout - HZ/50) / info->port->fifosize;
    char_time = char_time / 5;
    if (char_time == 0)
        char_time = 1;

    // Crazy!!   sometimes the input arg 'timeout' can be negtive numbers  :-(
    if (timeout >= 0 && 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 info->timeout, this is probably due to a
     * UART bug of some kind.  So, we clamp the timeout parameter at
     * 2*info->timeout.
     */
    if (!timeout || timeout > 2 * info->timeout)
        timeout = 2 * info->timeout;

    expire = jiffies + timeout;
    pr_debug("siccuart_wait_until_sent(%d), jiff=%lu, expire=%lu  char_time=%lu...\n",
           tty->index, jiffies,
           expire, char_time);
    while ((readb(info->port->uart_base + BL_SICC_LSR) & _LSR_TX_ALL) != _LSR_TX_ALL) {
        set_current_state(TASK_INTERRUPTIBLE);
        schedule_timeout(char_time);
        if (signal_pending(current))
            break;
        if (timeout && time_after(jiffies, expire))
            break;
    }
    set_current_state(TASK_RUNNING);
}

static void siccuart_hangup(struct tty_struct *tty)
{
    struct SICC_info *info = tty->driver_data;
    struct SICC_state *state = info->state;

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

static int block_til_ready(struct tty_struct *tty, struct file *filp,
               struct SICC_info *info)
{
    DECLARE_WAITQUEUE(wait, current);
    struct SICC_state *state = info->state;
    unsigned long flags;
    int do_clocal = 0, extra_count = 0, retval;

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

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

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

    /*
     * Block waiting for the carrier detect and the line to become
     * free (i.e., not in use by the callout).  While we are in
     * this loop, state->count is dropped by one, so that
     * rs_close() knows when to free things.  We restore it upon
     * exit, either normal or abnormal.
     */
    retval = 0;
    add_wait_queue(&info->open_wait, &wait);
    /* lock while decrementing state->count */
    spin_lock_irqsave(&info->state->sicc_lock,flags);
    if (!tty_hung_up_p(filp)) {
        extra_count = 1;
        state->count--;
    }
    spin_unlock_irqrestore(&info->state->sicc_lock,flags);
    info->blocked_open++;
    while (1) {
        /* disable interrupts while setting modem control lines */
        spin_lock_irqsave(&info->state->sicc_lock,flags);
        if (tty->termios->c_cflag & CBAUD) {
            info->mctrl = TIOCM_DTR | TIOCM_RTS;
            info->port->set_mctrl(info->port, info->mctrl);
        }
        spin_unlock_irqrestore(&info->state->sicc_lock,flags);
        set_current_state(TASK_INTERRUPTIBLE);
        if (tty_hung_up_p(filp) ||
            !(info->flags & ASYNC_INITIALIZED)) {
            if (info->flags & ASYNC_HUP_NOTIFY)
                retval = -EAGAIN;