[deliverable/linux.git] / drivers / char / tty_port.c

/*
 * Tty port functions
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/module.h>

void tty_port_init(struct tty_port *port)
{
	memset(port, 0, sizeof(*port));
	init_waitqueue_head(&port->open_wait);
	init_waitqueue_head(&port->close_wait);
	init_waitqueue_head(&port->delta_msr_wait);
	mutex_init(&port->mutex);
	spin_lock_init(&port->lock);
	port->close_delay = (50 * HZ) / 100;
	port->closing_wait = (3000 * HZ) / 100;
}
EXPORT_SYMBOL(tty_port_init);

int tty_port_alloc_xmit_buf(struct tty_port *port)
{
	/* We may sleep in get_zeroed_page() */
	mutex_lock(&port->mutex);
	if (port->xmit_buf == NULL)
		port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
	mutex_unlock(&port->mutex);
	if (port->xmit_buf == NULL)
		return -ENOMEM;
	return 0;
}
EXPORT_SYMBOL(tty_port_alloc_xmit_buf);

void tty_port_free_xmit_buf(struct tty_port *port)
{
	mutex_lock(&port->mutex);
	if (port->xmit_buf != NULL) {
		free_page((unsigned long)port->xmit_buf);
		port->xmit_buf = NULL;
	}
	mutex_unlock(&port->mutex);
}
EXPORT_SYMBOL(tty_port_free_xmit_buf);


/**
 *	tty_port_tty_get	-	get a tty reference
 *	@port: tty port
 *
 *	Return a refcount protected tty instance or NULL if the port is not
 *	associated with a tty (eg due to close or hangup)
 */

struct tty_struct *tty_port_tty_get(struct tty_port *port)
{
	unsigned long flags;
	struct tty_struct *tty;

	spin_lock_irqsave(&port->lock, flags);
	tty = tty_kref_get(port->tty);
	spin_unlock_irqrestore(&port->lock, flags);
	return tty;
}
EXPORT_SYMBOL(tty_port_tty_get);

/**
 *	tty_port_tty_set	-	set the tty of a port
 *	@port: tty port
 *	@tty: the tty
 *
 *	Associate the port and tty pair. Manages any internal refcounts.
 *	Pass NULL to deassociate a port
 */

void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	if (port->tty)
		tty_kref_put(port->tty);
	port->tty = tty_kref_get(tty);
	spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL(tty_port_tty_set);

static void tty_port_shutdown(struct tty_port *port)
{
	if (port->ops->shutdown &&
		test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
			port->ops->shutdown(port);

}

/**
 *	tty_port_hangup		-	hangup helper
 *	@port: tty port
 *
 *	Perform port level tty hangup flag and count changes. Drop the tty
 *	reference.
 */

void tty_port_hangup(struct tty_port *port)
{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	port->count = 0;
	port->flags &= ~ASYNC_NORMAL_ACTIVE;
	if (port->tty)
		tty_kref_put(port->tty);
	port->tty = NULL;
	spin_unlock_irqrestore(&port->lock, flags);
	wake_up_interruptible(&port->open_wait);
	wake_up_interruptible(&port->delta_msr_wait);
	tty_port_shutdown(port);
}
EXPORT_SYMBOL(tty_port_hangup);

/**
 *	tty_port_carrier_raised	-	carrier raised check
 *	@port: tty port
 *
 *	Wrapper for the carrier detect logic. For the moment this is used
 *	to hide some internal details. This will eventually become entirely
 *	internal to the tty port.
 */

int tty_port_carrier_raised(struct tty_port *port)
{
	if (port->ops->carrier_raised == NULL)
		return 1;
	return port->ops->carrier_raised(port);
}
EXPORT_SYMBOL(tty_port_carrier_raised);

/**
 *	tty_port_raise_dtr_rts	-	Raise DTR/RTS
 *	@port: tty port
 *
 *	Wrapper for the DTR/RTS raise logic. For the moment this is used
 *	to hide some internal details. This will eventually become entirely
 *	internal to the tty port.
 */

void tty_port_raise_dtr_rts(struct tty_port *port)
{
	if (port->ops->dtr_rts)
		port->ops->dtr_rts(port, 1);
}
EXPORT_SYMBOL(tty_port_raise_dtr_rts);

/**
 *	tty_port_lower_dtr_rts	-	Lower DTR/RTS
 *	@port: tty port
 *
 *	Wrapper for the DTR/RTS raise logic. For the moment this is used
 *	to hide some internal details. This will eventually become entirely
 *	internal to the tty port.
 */

void tty_port_lower_dtr_rts(struct tty_port *port)
{
	if (port->ops->dtr_rts)
		port->ops->dtr_rts(port, 0);
}
EXPORT_SYMBOL(tty_port_lower_dtr_rts);

/**
 *	tty_port_block_til_ready	-	Waiting logic for tty open
 *	@port: the tty port being opened
 *	@tty: the tty device being bound
 *	@filp: the file pointer of the opener
 *
 *	Implement the core POSIX/SuS tty behaviour when opening a tty device.
 *	Handles:
 *		- hangup (both before and during)
 *		- non blocking open
 *		- rts/dtr/dcd
 *		- signals
 *		- port flags and counts
 *
 *	The passed tty_port must implement the carrier_raised method if it can
 *	do carrier detect and the dtr_rts method if it supports software
 *	management of these lines. Note that the dtr/rts raise is done each
 *	iteration as a hangup may have previously dropped them while we wait.
 */
 
int tty_port_block_til_ready(struct tty_port *port,
				struct tty_struct *tty, struct file *filp)
{
	int do_clocal = 0, retval;
	unsigned long flags;
	DEFINE_WAIT(wait);
	int cd;

	/* block if port is in the process of being closed */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
		wait_event_interruptible(port->close_wait,
				!(port->flags & ASYNC_CLOSING));
		if (port->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
	}

	/* if non-blocking mode is set we can pass directly to open unless
	   the port has just hung up or is in another error state */
	if ((filp->f_flags & O_NONBLOCK) ||
			(tty->flags & (1 << TTY_IO_ERROR))) {
		/* Indicate we are open */
		if (tty->termios->c_cflag & CBAUD)
			tty_port_raise_dtr_rts(port);
		port->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	if (C_CLOCAL(tty))
		do_clocal = 1;

	/* Block waiting until we can proceed. We may need to wait for the
	   carrier, but we must also wait for any close that is in progress
	   before the next open may complete */

	retval = 0;

	/* The port lock protects the port counts */
	spin_lock_irqsave(&port->lock, flags);
	if (!tty_hung_up_p(filp))
		port->count--;
	port->blocked_open++;
	spin_unlock_irqrestore(&port->lock, flags);

	while (1) {
		/* Indicate we are open */
		if (tty->termios->c_cflag & CBAUD)
			tty_port_raise_dtr_rts(port);

		prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
		/* Check for a hangup or uninitialised port. Return accordingly */
		if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
			if (port->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;
			break;
		}
		/* Probe the carrier. For devices with no carrier detect this
		   will always return true */
		cd = tty_port_carrier_raised(port);
		if (!(port->flags & ASYNC_CLOSING) &&
				(do_clocal || cd))
			break;
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	finish_wait(&port->open_wait, &wait);

	/* Update counts. A parallel hangup will have set count to zero and
	   we must not mess that up further */
	spin_lock_irqsave(&port->lock, flags);
	if (!tty_hung_up_p(filp))
		port->count++;
	port->blocked_open--;
	if (retval == 0)
		port->flags |= ASYNC_NORMAL_ACTIVE;
	spin_unlock_irqrestore(&port->lock, flags);
	return retval;
	
}
EXPORT_SYMBOL(tty_port_block_til_ready);

int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, struct file *filp)
{
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	if (tty_hung_up_p(filp)) {
		spin_unlock_irqrestore(&port->lock, flags);
		return 0;
	}

	if( tty->count == 1 && port->count != 1) {
		printk(KERN_WARNING
		    "tty_port_close_start: tty->count = 1 port count = %d.\n",
								port->count);
		port->count = 1;
	}
	if (--port->count < 0) {
		printk(KERN_WARNING "tty_port_close_start: count = %d\n",
								port->count);
		port->count = 0;
	}

	if (port->count) {
		spin_unlock_irqrestore(&port->lock, flags);
		if (port->ops->drop)
			port->ops->drop(port);
		return 0;
	}
	set_bit(ASYNCB_CLOSING, &port->flags);
	tty->closing = 1;
	spin_unlock_irqrestore(&port->lock, flags);
	/* Don't block on a stalled port, just pull the chain */
	if (tty->flow_stopped)
		tty_driver_flush_buffer(tty);
	if (test_bit(ASYNCB_INITIALIZED, &port->flags) &&
			port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, port->closing_wait);
	if (port->drain_delay) {
		unsigned int bps = tty_get_baud_rate(tty);
		long timeout;

		if (bps > 1200)
			timeout = max_t(long, (HZ * 10 * port->drain_delay) / bps,
								HZ / 10);
		else
			timeout = 2 * HZ;
		schedule_timeout_interruptible(timeout);
	}
	/* Don't call port->drop for the last reference. Callers will want
	   to drop the last active reference in ->shutdown() or the tty
	   shutdown path */
	return 1;
}
EXPORT_SYMBOL(tty_port_close_start);

void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
{
	unsigned long flags;

	tty_ldisc_flush(tty);

	if (tty->termios->c_cflag & HUPCL)
		tty_port_lower_dtr_rts(port);

	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);
		wake_up_interruptible(&port->open_wait);
	}
	port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING);
	wake_up_interruptible(&port->close_wait);
	spin_unlock_irqrestore(&port->lock, flags);
}
EXPORT_SYMBOL(tty_port_close_end);

void tty_port_close(struct tty_port *port, struct tty_struct *tty,
							struct file *filp)
{
	if (tty_port_close_start(port, tty, filp) == 0)
		return;
	tty_port_shutdown(port);
	tty_port_close_end(port, tty);
	tty_port_tty_set(port, NULL);
}
EXPORT_SYMBOL(tty_port_close);
Commit	Line	Data
9e48565d AC	1	/*
	2	* Tty port functions
	3	*/
	4
	5	#include <linux/types.h>
	6	#include <linux/errno.h>
	7	#include <linux/tty.h>
	8	#include <linux/tty_driver.h>
	9	#include <linux/tty_flip.h>
3e61696b	10	#include <linux/serial.h>
9e48565d AC	11	#include <linux/timer.h>
	12	#include <linux/string.h>
	13	#include <linux/slab.h>
	14	#include <linux/sched.h>
	15	#include <linux/init.h>
	16	#include <linux/wait.h>
	17	#include <linux/bitops.h>
	18	#include <linux/delay.h>
	19	#include <linux/module.h>
	20
	21	void tty_port_init(struct tty_port *port)
	22	{
	23	memset(port, 0, sizeof(*port));
	24	init_waitqueue_head(&port->open_wait);
	25	init_waitqueue_head(&port->close_wait);
bdc04e31	26	init_waitqueue_head(&port->delta_msr_wait);
9e48565d	27	mutex_init(&port->mutex);
4a90f09b	28	spin_lock_init(&port->lock);
9e48565d AC	29	port->close_delay = (50 * HZ) / 100;
	30	port->closing_wait = (3000 * HZ) / 100;
	31	}
	32	EXPORT_SYMBOL(tty_port_init);
	33
	34	int tty_port_alloc_xmit_buf(struct tty_port *port)
	35	{
	36	/* We may sleep in get_zeroed_page() */
	37	mutex_lock(&port->mutex);
	38	if (port->xmit_buf == NULL)
	39	port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
	40	mutex_unlock(&port->mutex);
	41	if (port->xmit_buf == NULL)
	42	return -ENOMEM;
	43	return 0;
	44	}
	45	EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
	46
	47	void tty_port_free_xmit_buf(struct tty_port *port)
	48	{
	49	mutex_lock(&port->mutex);
	50	if (port->xmit_buf != NULL) {
	51	free_page((unsigned long)port->xmit_buf);
	52	port->xmit_buf = NULL;
	53	}
	54	mutex_unlock(&port->mutex);
	55	}
	56	EXPORT_SYMBOL(tty_port_free_xmit_buf);
	57
	58
4a90f09b AC	59	/**
	60	* tty_port_tty_get - get a tty reference
	61	* @port: tty port
	62	*
	63	* Return a refcount protected tty instance or NULL if the port is not
	64	* associated with a tty (eg due to close or hangup)
	65	*/
	66
	67	struct tty_struct tty_port_tty_get(struct tty_port port)
	68	{
	69	unsigned long flags;
	70	struct tty_struct *tty;
	71
	72	spin_lock_irqsave(&port->lock, flags);
	73	tty = tty_kref_get(port->tty);
	74	spin_unlock_irqrestore(&port->lock, flags);
	75	return tty;
	76	}
	77	EXPORT_SYMBOL(tty_port_tty_get);
	78
	79	/**
	80	* tty_port_tty_set - set the tty of a port
	81	* @port: tty port
	82	* @tty: the tty
	83	*
	84	* Associate the port and tty pair. Manages any internal refcounts.
	85	* Pass NULL to deassociate a port
	86	*/
	87
	88	void tty_port_tty_set(struct tty_port port, struct tty_struct tty)
	89	{
	90	unsigned long flags;
	91
	92	spin_lock_irqsave(&port->lock, flags);
	93	if (port->tty)
	94	tty_kref_put(port->tty);
cb4bca35	95	port->tty = tty_kref_get(tty);
4a90f09b AC	96	spin_unlock_irqrestore(&port->lock, flags);
	97	}
	98	EXPORT_SYMBOL(tty_port_tty_set);
31f35939	99
7ca0ff9a AC	100	static void tty_port_shutdown(struct tty_port *port)
	101	{
	102	if (port->ops->shutdown &&
1f5c13fa	103	test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
7ca0ff9a AC	104	port->ops->shutdown(port);
	105
	106	}
	107
3e61696b AC	108	/**
	109	* tty_port_hangup - hangup helper
	110	* @port: tty port
	111	*
	112	* Perform port level tty hangup flag and count changes. Drop the tty
	113	* reference.
	114	*/
	115
	116	void tty_port_hangup(struct tty_port *port)
	117	{
	118	unsigned long flags;
	119
	120	spin_lock_irqsave(&port->lock, flags);
	121	port->count = 0;
	122	port->flags &= ~ASYNC_NORMAL_ACTIVE;
	123	if (port->tty)
	124	tty_kref_put(port->tty);
	125	port->tty = NULL;
	126	spin_unlock_irqrestore(&port->lock, flags);
	127	wake_up_interruptible(&port->open_wait);
bdc04e31	128	wake_up_interruptible(&port->delta_msr_wait);
7ca0ff9a	129	tty_port_shutdown(port);
3e61696b AC	130	}
	131	EXPORT_SYMBOL(tty_port_hangup);
	132
31f35939 AC	133	/**
	134	* tty_port_carrier_raised - carrier raised check
	135	* @port: tty port
	136	*
	137	* Wrapper for the carrier detect logic. For the moment this is used
	138	* to hide some internal details. This will eventually become entirely
	139	* internal to the tty port.
	140	*/
	141
	142	int tty_port_carrier_raised(struct tty_port *port)
	143	{
	144	if (port->ops->carrier_raised == NULL)
	145	return 1;
	146	return port->ops->carrier_raised(port);
	147	}
	148	EXPORT_SYMBOL(tty_port_carrier_raised);
5d951fb4 AC	149
5d951fb4 AC	150	/**
fcc8ac18	151	* tty_port_raise_dtr_rts - Raise DTR/RTS
5d951fb4 AC	152	* @port: tty port
	153	*
	154	* Wrapper for the DTR/RTS raise logic. For the moment this is used
	155	* to hide some internal details. This will eventually become entirely
	156	* internal to the tty port.
	157	*/
	158
	159	void tty_port_raise_dtr_rts(struct tty_port *port)
	160	{
fcc8ac18 AC	161	if (port->ops->dtr_rts)
fcc8ac18 AC	162	port->ops->dtr_rts(port, 1);
5d951fb4 AC	163	}
5d951fb4 AC	164	EXPORT_SYMBOL(tty_port_raise_dtr_rts);
36c621d8	165
fcc8ac18 AC	166	/**
	167	* tty_port_lower_dtr_rts - Lower DTR/RTS
	168	* @port: tty port
	169	*
	170	* Wrapper for the DTR/RTS raise logic. For the moment this is used
	171	* to hide some internal details. This will eventually become entirely
	172	* internal to the tty port.
	173	*/
	174
	175	void tty_port_lower_dtr_rts(struct tty_port *port)
	176	{
	177	if (port->ops->dtr_rts)
	178	port->ops->dtr_rts(port, 0);
	179	}
	180	EXPORT_SYMBOL(tty_port_lower_dtr_rts);
	181
36c621d8 AC	182	/**
	183	* tty_port_block_til_ready - Waiting logic for tty open
	184	* @port: the tty port being opened
	185	* @tty: the tty device being bound
	186	* @filp: the file pointer of the opener
	187	*
	188	* Implement the core POSIX/SuS tty behaviour when opening a tty device.
	189	* Handles:
	190	* - hangup (both before and during)
	191	* - non blocking open
	192	* - rts/dtr/dcd
	193	* - signals
	194	* - port flags and counts
	195	*
	196	* The passed tty_port must implement the carrier_raised method if it can
fcc8ac18	197	* do carrier detect and the dtr_rts method if it supports software
36c621d8 AC	198	* management of these lines. Note that the dtr/rts raise is done each
	199	* iteration as a hangup may have previously dropped them while we wait.
	200	*/
	201
	202	int tty_port_block_til_ready(struct tty_port *port,
	203	struct tty_struct tty, struct file filp)
	204	{
	205	int do_clocal = 0, retval;
	206	unsigned long flags;
6af9a43d	207	DEFINE_WAIT(wait);
36c621d8 AC	208	int cd;
	209
	210	/* block if port is in the process of being closed */
	211	if (tty_hung_up_p(filp) \|\| port->flags & ASYNC_CLOSING) {
5fc5b42a JS	212	wait_event_interruptible(port->close_wait,
5fc5b42a JS	213	!(port->flags & ASYNC_CLOSING));
36c621d8 AC	214	if (port->flags & ASYNC_HUP_NOTIFY)
	215	return -EAGAIN;
	216	else
	217	return -ERESTARTSYS;
	218	}
	219
	220	/* if non-blocking mode is set we can pass directly to open unless
	221	the port has just hung up or is in another error state */
	222	if ((filp->f_flags & O_NONBLOCK) \|\|
	223	(tty->flags & (1 << TTY_IO_ERROR))) {
4175f3e3 AC	224	/* Indicate we are open */
	225	if (tty->termios->c_cflag & CBAUD)
	226	tty_port_raise_dtr_rts(port);
36c621d8 AC	227	port->flags \|= ASYNC_NORMAL_ACTIVE;
	228	return 0;
	229	}
	230
	231	if (C_CLOCAL(tty))
	232	do_clocal = 1;
	233
	234	/* Block waiting until we can proceed. We may need to wait for the
	235	carrier, but we must also wait for any close that is in progress
	236	before the next open may complete */
	237
	238	retval = 0;
36c621d8 AC	239
	240	/* The port lock protects the port counts */
	241	spin_lock_irqsave(&port->lock, flags);
	242	if (!tty_hung_up_p(filp))
	243	port->count--;
	244	port->blocked_open++;
	245	spin_unlock_irqrestore(&port->lock, flags);
	246
	247	while (1) {
	248	/* Indicate we are open */
7834909f AC	249	if (tty->termios->c_cflag & CBAUD)
7834909f AC	250	tty_port_raise_dtr_rts(port);
36c621d8	251
3e3b5c08	252	prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
36c621d8 AC	253	/* Check for a hangup or uninitialised port. Return accordingly */
	254	if (tty_hung_up_p(filp) \|\| !(port->flags & ASYNC_INITIALIZED)) {
	255	if (port->flags & ASYNC_HUP_NOTIFY)
	256	retval = -EAGAIN;
	257	else
	258	retval = -ERESTARTSYS;
	259	break;
	260	}
	261	/* Probe the carrier. For devices with no carrier detect this
	262	will always return true */
	263	cd = tty_port_carrier_raised(port);
	264	if (!(port->flags & ASYNC_CLOSING) &&
	265	(do_clocal \|\| cd))
	266	break;
	267	if (signal_pending(current)) {
	268	retval = -ERESTARTSYS;
	269	break;
	270	}
	271	schedule();
	272	}
3e3b5c08	273	finish_wait(&port->open_wait, &wait);
36c621d8 AC	274
	275	/* Update counts. A parallel hangup will have set count to zero and
	276	we must not mess that up further */
	277	spin_lock_irqsave(&port->lock, flags);
	278	if (!tty_hung_up_p(filp))
	279	port->count++;
	280	port->blocked_open--;
	281	if (retval == 0)
	282	port->flags \|= ASYNC_NORMAL_ACTIVE;
	283	spin_unlock_irqrestore(&port->lock, flags);
ecc2e05e	284	return retval;
36c621d8 AC	285
	286	}
	287	EXPORT_SYMBOL(tty_port_block_til_ready);
	288
a6614999 AC	289	int tty_port_close_start(struct tty_port port, struct tty_struct tty, struct file *filp)
	290	{
	291	unsigned long flags;
	292
	293	spin_lock_irqsave(&port->lock, flags);
	294	if (tty_hung_up_p(filp)) {
	295	spin_unlock_irqrestore(&port->lock, flags);
	296	return 0;
	297	}
	298
	299	if( tty->count == 1 && port->count != 1) {
	300	printk(KERN_WARNING
	301	"tty_port_close_start: tty->count = 1 port count = %d.\n",
	302	port->count);
	303	port->count = 1;
	304	}
	305	if (--port->count < 0) {
	306	printk(KERN_WARNING "tty_port_close_start: count = %d\n",
	307	port->count);
	308	port->count = 0;
	309	}
	310
	311	if (port->count) {
	312	spin_unlock_irqrestore(&port->lock, flags);
7ca0ff9a AC	313	if (port->ops->drop)
7ca0ff9a AC	314	port->ops->drop(port);
a6614999 AC	315	return 0;
a6614999 AC	316	}
1f5c13fa	317	set_bit(ASYNCB_CLOSING, &port->flags);
a6614999 AC	318	tty->closing = 1;
a6614999 AC	319	spin_unlock_irqrestore(&port->lock, flags);
fba85e01 AC	320	/* Don't block on a stalled port, just pull the chain */
	321	if (tty->flow_stopped)
	322	tty_driver_flush_buffer(tty);
7ca0ff9a	323	if (test_bit(ASYNCB_INITIALIZED, &port->flags) &&
6ed1dbae	324	port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
a6614999	325	tty_wait_until_sent(tty, port->closing_wait);
1ec739be AC	326	if (port->drain_delay) {
	327	unsigned int bps = tty_get_baud_rate(tty);
	328	long timeout;
	329
	330	if (bps > 1200)
	331	timeout = max_t(long, (HZ * 10 * port->drain_delay) / bps,
	332	HZ / 10);
	333	else
	334	timeout = 2 * HZ;
	335	schedule_timeout_interruptible(timeout);
	336	}
7ca0ff9a AC	337	/* Don't call port->drop for the last reference. Callers will want
	338	to drop the last active reference in ->shutdown() or the tty
	339	shutdown path */
a6614999 AC	340	return 1;
	341	}
	342	EXPORT_SYMBOL(tty_port_close_start);
	343
	344	void tty_port_close_end(struct tty_port port, struct tty_struct tty)
	345	{
	346	unsigned long flags;
	347
	348	tty_ldisc_flush(tty);
	349
fcc8ac18 AC	350	if (tty->termios->c_cflag & HUPCL)
	351	tty_port_lower_dtr_rts(port);
	352
a6614999 AC	353	spin_lock_irqsave(&port->lock, flags);
	354	tty->closing = 0;
	355
	356	if (port->blocked_open) {
	357	spin_unlock_irqrestore(&port->lock, flags);
	358	if (port->close_delay) {
	359	msleep_interruptible(
	360	jiffies_to_msecs(port->close_delay));
	361	}
	362	spin_lock_irqsave(&port->lock, flags);
	363	wake_up_interruptible(&port->open_wait);
	364	}
	365	port->flags &= ~(ASYNC_NORMAL_ACTIVE \| ASYNC_CLOSING);
	366	wake_up_interruptible(&port->close_wait);
	367	spin_unlock_irqrestore(&port->lock, flags);
	368	}
	369	EXPORT_SYMBOL(tty_port_close_end);
7ca0ff9a AC	370
	371	void tty_port_close(struct tty_port port, struct tty_struct tty,
	372	struct file *filp)
	373	{
	374	if (tty_port_close_start(port, tty, filp) == 0)
	375	return;
	376	tty_port_shutdown(port);
	377	tty_port_close_end(port, tty);
	378	tty_port_tty_set(port, NULL);
	379	}
	380	EXPORT_SYMBOL(tty_port_close);