core.c

IXP425 平台下嵌入式LINUX的串口的驱动程序

		}
		wake_up_interruptible(&info->open_wait);
	} else {
#ifdef CONFIG_PM
		/*
		 * Put device into D3 state.
		 */
		pm_send(info->state->pm, PM_SUSPEND, (void *)3);
#else
		if (info->ops->pm)
			info->ops->pm(info->port, 3, 0);
#endif
	}

	info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE|
			 ASYNC_CLOSING);
	wake_up_interruptible(&info->close_wait);

done:
	if (drv->owner)
		__MOD_DEC_USE_COUNT(drv->owner);
}

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

	if (info->port->type == PORT_UNKNOWN ||
	    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;
	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 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;
#ifdef DEBUG
	printk("uart_wait_until_sent(%d), jiff=%lu, expire=%lu...\n",
	       MINOR(tty->device) - tty->driver.minor_start, jiffies,
	       expire);
#endif
	while (!info->ops->tx_empty(info->port)) {
		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); /* might not be needed */
}

/*
 * This is called with the BKL in effect
 *  linux/drivers/char/tty_io.c:do_tty_hangup()
 */
static void uart_hangup(struct tty_struct *tty)
{
	struct uart_info *info = tty->driver_data;
	struct uart_state *state = info->state;

	uart_flush_buffer(tty);
	if (info->flags & ASYNC_CLOSING)
		return;
	uart_shutdown(info);
	info->event = 0;
	state->count = 0;
	info->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE);
	info->tty = NULL;
	wake_up_interruptible(&info->open_wait);
}

static int uart_block_til_ready(struct tty_struct *tty, struct file *filp,
				struct uart_info *info)
{
	DECLARE_WAITQUEUE(wait, current);
	struct uart_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 this is a callout device, then just make sure the normal
	 * device isn't being used.
	 */
	if (tty->driver.subtype == SERIAL_TYPE_CALLOUT) {
		if (info->flags & ASYNC_NORMAL_ACTIVE)
			return -EBUSY;
		if ((info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (info->flags & ASYNC_SESSION_LOCKOUT) &&
		    (info->session != current->session))
			return -EBUSY;
		if ((info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (info->flags & ASYNC_PGRP_LOCKOUT) &&
		    (info->pgrp != current->pgrp))
			return -EBUSY;
		info->flags |= ASYNC_CALLOUT_ACTIVE;
		return 0;
	}

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

	if (info->flags & ASYNC_CALLOUT_ACTIVE) {
		if (state->normal_termios.c_cflag & CLOCAL)
			do_clocal = 1;
	} else {
		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);
	down(&state->count_sem);
	spin_lock_irqsave(&info->lock, flags);
	if (!tty_hung_up_p(filp)) {
		extra_count = 1;
		state->count--;
	}
	spin_unlock_irqrestore(&info->lock, flags);
	info->blocked_open++;
	up(&state->count_sem);
	while (1) {
		spin_lock_irqsave(&info->lock, flags);
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (tty->termios->c_cflag & CBAUD)) {
			info->mctrl |= TIOCM_DTR | TIOCM_RTS;
			info->ops->set_mctrl(info->port, info->mctrl);
		}
		spin_unlock_irqrestore(&info->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;
			else
				retval = -ERESTARTSYS;
			break;
		}
		if (!(info->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(info->flags & ASYNC_CLOSING) &&
		    (do_clocal ||
		     (info->ops->get_mctrl(info->port) & TIOCM_CAR)))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&info->open_wait, &wait);
	down(&state->count_sem);
	if (extra_count)
		state->count++;
	info->blocked_open--;
	up(&state->count_sem);
	if (retval)
		return retval;
	info->flags |= ASYNC_NORMAL_ACTIVE;
	return 0;
}

static struct uart_info *uart_get(struct uart_driver *drv, int line)
{
	struct uart_state *state = drv->state + line;
	struct uart_info *info;

	down(&state->count_sem);
	state->count++;
	if (state->info)
		goto out;

	info = kmalloc(sizeof(struct uart_info), GFP_KERNEL);
	if (info) {
		memset(info, 0, sizeof(struct uart_info));
		init_waitqueue_head(&info->open_wait);
		init_waitqueue_head(&info->close_wait);
		init_waitqueue_head(&info->delta_msr_wait);
		info->port  = state->port;
		info->flags = info->port->flags;
		info->ops   = info->port->ops;
		info->state = state;
		tasklet_init(&info->tlet, uart_tasklet_action,
			     (unsigned long)info);
	}
	if (state->info)
		kfree(info);
	else
		state->info = info;
out:
	up(&state->count_sem);
	return state->info;
}

/*
 * Make sure we have the temporary buffer allocated.  Note
 * that we set retval appropriately above, and we rely on
 * this.
 */
static inline int uart_alloc_tmpbuf(void)
{
	if (!tmp_buf) {
		unsigned long buf = get_zeroed_page(GFP_KERNEL);
		if (!tmp_buf) {
			if (buf)
				tmp_buf = (u_char *)buf;
			else
				return -ENOMEM;
		} else
			free_page(buf);
	}
	return 0;
}

/*
 * In 2.4.5, calls to uart_open are serialised by the BKL in
 *   linux/fs/devices.c:chrdev_open()
 * Note that if this fails, then uart_close() _will_ be called.
 */
static int uart_open(struct tty_struct *tty, struct file *filp)
{
	struct uart_driver *drv = (struct uart_driver *)tty->driver.driver_state;
	struct uart_info *info;
	int retval, line = MINOR(tty->device) - tty->driver.minor_start;

#ifdef DEBUG
	printk("uart_open(%d) called\n", line);
#endif

	retval = -ENODEV;
	if (line >= tty->driver.num)
		goto fail;

	if (!try_inc_mod_count(drv->owner))
		goto fail;

	info = uart_get(drv, line);
	retval = -ENOMEM;
	if (!info)
		goto out;

	/*
	 * Set the tty driver_data.  If we fail from this point on,
	 * the generic tty layer will cause uart_close(), which will
	 * decrement the module use count.
	 */
	tty->driver_data = info;
	info->tty = tty;
	info->tty->low_latency = (info->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	if (uart_alloc_tmpbuf())
		goto fail;

	/*
	 * If the port is in 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);
		retval = (info->flags & ASYNC_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS;
		goto fail;
	}

	/*
	 * Make sure the device is in D0 state.
	 */
	if (info->state->count == 1)
#ifdef CONFIG_PM
		pm_send(info->state->pm, PM_RESUME, (void *)0);
#else
		if (info->ops->pm)
			info->ops->pm(info->port, 0, 3);
#endif

	/*
	 * Start up the serial port
	 */
	retval = uart_startup(info);
	if (retval)
		goto fail;

	retval = uart_block_til_ready(tty, filp, info);
	if (retval)
		goto fail;

	if (info->state->count == 1) {
		int changed_termios = 0;

		if (info->flags & ASYNC_SPLIT_TERMIOS) {
			if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
				*tty->termios = info->state->normal_termios;
			else
				*tty->termios = info->state->callout_termios;
			changed_termios = 1;
		}

#ifdef CONFIG_SERIAL_CORE_CONSOLE
		/*
		 * Copy across the serial console cflag setting
		 */
		{
			struct console *c = drv->cons;
			if (c && c->cflag && c->index == line) {
				tty->termios->c_cflag = c->cflag;
				c->cflag = 0;
				changed_termios = 1;
			}
		}
#endif
		if (changed_termios)
			uart_change_speed(info, NULL);
	}

	info->session = current->session;
	info->pgrp = current->pgrp;
	return 0;

out:
	if (drv->owner)
		__MOD_DEC_USE_COUNT(drv->owner);
fail:
	return retval;
}

#ifdef CONFIG_PROC_FS

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;
}

static int uart_line_info(char *buf, struct uart_driver *drv, int i)
{
	struct uart_state *state = drv->state + i;
	struct uart_port *port = state->port;
	char stat_buf[32];
	u_int status;
	int ret;

	ret = sprintf(buf, "%d: uart:%s port:%08X irq:%d",
			port->line, uart_type(port),
			port->iobase, port->irq);

	if (port->type == PORT_UNKNOWN) {
		strcat(buf, "\n");
		return ret + 1;
	}

	status = port->ops->get_mctrl(port);

	ret += sprintf(buf + ret, " tx:%d rx:%d",
			port->icount.tx, port->icount.rx);
	if (port->icount.frame)
		ret += sprintf(buf + ret, " fe:%d",
			port->icount.frame);
	if (port->icount.parity)
		ret += sprintf(buf + ret, " pe:%d",
			port->icount.parity);
	if (port->icount.brk)
		ret += sprintf(buf + ret, " brk:%d",
			port->icount.brk);
	if (port->icount.overrun)
		ret += sprintf(buf + ret, " oe:%d",
			port->icount.overrun);

#define INFOBIT(bit,str) \
	if (state->info && state->info->mctrl & (bit)) \
		strcat(stat_buf, (str))
#define STATBIT(bit,str) \
	if (status & (bit)) \
		strcat(stat_buf, (str))

	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] = ' ';
	strcat(stat_buf, "\n");

	ret += sprintf(buf + ret, stat_buf);
	return ret;
}

static int uart_read_proc(char *page, char **start, off_t off,
			  int count, int *eof, void *data)
{
	struct tty_driver *ttydrv = data;
	struct uart_driver *drv = ttydrv->driver_state;
	int i, len = 0, l;
	off_t begin = 0;

	len += sprintf(page, "serinfo:1.0 driver%s%s revision:%s\n",
			"", "", "");
	for (i = 0; i < drv->nr && len < PAGE_SIZE - 96; i++) {
		l = uart_line_info(page + len, drv, i);
		len += l;
		if (len + begin > off + count)
			goto done;
		if (len + begin < off) {
			begin += len;
			len = 0;
		}
	}
	*eof = 1;
done:
	if (off >= len + begin)
		return 0;
	*start = page + (off - begin);
	return (count < begin + len - off) ? count : (begin + len - off);
}
#endif

#ifdef CONFIG_SERIAL_CORE_CONSOLE
/*
 *	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;
}

/**
 *	uart_parse_options - Parse serial port baud/parity/bits/flow contro.
 *	@options: pointer to option string
 *	@baud: pointer to an 'int' variable for the baud rate.
 *	@parity: pointer to an 'int' variable for the parity.
 *	@bits: pointer to an 'int' variable for the number of data bits.
 *	@flow: pointer to an 'int' variable for the flow control character.
 *
 *	uart_parse_options decodes a string containing the serial console
 *	options.  The format of the string is <baud><parity><bits><flow>,
 *	eg: 115200n8r
 */
void __init
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;
}

/**
 *	uart_set_options - setup the serial console parameters
 *	@port: pointer to the serial ports uart_port structure
 *	@co: console pointer
 *	@baud: baud rate
 *	@parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
 *	@bits: number of data bits
 *	@flow: flow control character - 'r' (rts)
 */
int __init
uart_set_options(struct uart_port *port, struct console *co,
		 int baud, int parity, int bits, int flow)
{
	u_int cflag = CREAD | HUPCL | CLOCAL;
	u_int quot;

	/*
	 * Construct a cflag setting.
	 */
	switch (baud) {
	case 1200:	cflag |= B1200;			break;
	case 2400:	cflag |= B2400;			break;
	case 4800:	cflag |= B4800;			break;
	case 9600:	cflag |= B9600;			break;
	case 19200:	cflag |= B19200;		break;
	default:	cflag |= B38400;  baud = 38400;	break;
	case 57600:	cflag |= B57600;		break;
	case 115200:	cflag |= B115200;		break;
	case 230400:	cflag |= B230400;		break;
	case 460800:	cflag |= B460800;		break;
	}

	if (bits == 7)