[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);
	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);

/**
 *	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);
}
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	-	Riase 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->raise_dtr_rts)
		port->ops->raise_dtr_rts(port);
}
EXPORT_SYMBOL(tty_port_raise_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 raise_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;
	DECLARE_WAITQUEUE(wait, current);
	int cd;

	/* block if port is in the process of being closed */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
		interruptible_sleep_on(&port->close_wait);
		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))) {
		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;
	add_wait_queue(&port->open_wait, &wait);

	/* 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);

		set_current_state(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();
	}
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&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 0;
	
}
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);
		return 0;
	}
	port->flags |= ASYNC_CLOSING;
	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 (port->flags & ASYNC_INITIALIZED &&
			port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		tty_wait_until_sent(tty, port->closing_wait);
	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);

	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);
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);
	26	mutex_init(&port->mutex);
4a90f09b	27	spin_lock_init(&port->lock);
9e48565d AC	28	port->close_delay = (50 * HZ) / 100;
	29	port->closing_wait = (3000 * HZ) / 100;
	30	}
	31	EXPORT_SYMBOL(tty_port_init);
	32
	33	int tty_port_alloc_xmit_buf(struct tty_port *port)
	34	{
	35	/* We may sleep in get_zeroed_page() */
	36	mutex_lock(&port->mutex);
	37	if (port->xmit_buf == NULL)
	38	port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
	39	mutex_unlock(&port->mutex);
	40	if (port->xmit_buf == NULL)
	41	return -ENOMEM;
	42	return 0;
	43	}
	44	EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
	45
	46	void tty_port_free_xmit_buf(struct tty_port *port)
	47	{
	48	mutex_lock(&port->mutex);
	49	if (port->xmit_buf != NULL) {
	50	free_page((unsigned long)port->xmit_buf);
	51	port->xmit_buf = NULL;
	52	}
	53	mutex_unlock(&port->mutex);
	54	}
	55	EXPORT_SYMBOL(tty_port_free_xmit_buf);
	56
	57
4a90f09b AC	58	/**
	59	* tty_port_tty_get - get a tty reference
	60	* @port: tty port
	61	*
	62	* Return a refcount protected tty instance or NULL if the port is not
	63	* associated with a tty (eg due to close or hangup)
	64	*/
	65
	66	struct tty_struct tty_port_tty_get(struct tty_port port)
	67	{
	68	unsigned long flags;
	69	struct tty_struct *tty;
	70
	71	spin_lock_irqsave(&port->lock, flags);
	72	tty = tty_kref_get(port->tty);
	73	spin_unlock_irqrestore(&port->lock, flags);
	74	return tty;
	75	}
	76	EXPORT_SYMBOL(tty_port_tty_get);
	77
	78	/**
	79	* tty_port_tty_set - set the tty of a port
	80	* @port: tty port
	81	* @tty: the tty
	82	*
	83	* Associate the port and tty pair. Manages any internal refcounts.
	84	* Pass NULL to deassociate a port
	85	*/
	86
	87	void tty_port_tty_set(struct tty_port port, struct tty_struct tty)
	88	{
	89	unsigned long flags;
	90
	91	spin_lock_irqsave(&port->lock, flags);
	92	if (port->tty)
	93	tty_kref_put(port->tty);
cb4bca35	94	port->tty = tty_kref_get(tty);
4a90f09b AC	95	spin_unlock_irqrestore(&port->lock, flags);
	96	}
	97	EXPORT_SYMBOL(tty_port_tty_set);
31f35939	98
3e61696b AC	99	/**
	100	* tty_port_hangup - hangup helper
	101	* @port: tty port
	102	*
	103	* Perform port level tty hangup flag and count changes. Drop the tty
	104	* reference.
	105	*/
	106
	107	void tty_port_hangup(struct tty_port *port)
	108	{
	109	unsigned long flags;
	110
	111	spin_lock_irqsave(&port->lock, flags);
	112	port->count = 0;
	113	port->flags &= ~ASYNC_NORMAL_ACTIVE;
	114	if (port->tty)
	115	tty_kref_put(port->tty);
	116	port->tty = NULL;
	117	spin_unlock_irqrestore(&port->lock, flags);
	118	wake_up_interruptible(&port->open_wait);
	119	}
	120	EXPORT_SYMBOL(tty_port_hangup);
	121
31f35939 AC	122	/**
	123	* tty_port_carrier_raised - carrier raised check
	124	* @port: tty port
	125	*
	126	* Wrapper for the carrier detect logic. For the moment this is used
	127	* to hide some internal details. This will eventually become entirely
	128	* internal to the tty port.
	129	*/
	130
	131	int tty_port_carrier_raised(struct tty_port *port)
	132	{
	133	if (port->ops->carrier_raised == NULL)
	134	return 1;
	135	return port->ops->carrier_raised(port);
	136	}
	137	EXPORT_SYMBOL(tty_port_carrier_raised);
5d951fb4 AC	138
	139	/**
	140	* tty_port_raise_dtr_rts - Riase DTR/RTS
	141	* @port: tty port
	142	*
	143	* Wrapper for the DTR/RTS raise logic. For the moment this is used
	144	* to hide some internal details. This will eventually become entirely
	145	* internal to the tty port.
	146	*/
	147
	148	void tty_port_raise_dtr_rts(struct tty_port *port)
	149	{
	150	if (port->ops->raise_dtr_rts)
	151	port->ops->raise_dtr_rts(port);
	152	}
	153	EXPORT_SYMBOL(tty_port_raise_dtr_rts);
36c621d8 AC	154
	155	/**
	156	* tty_port_block_til_ready - Waiting logic for tty open
	157	* @port: the tty port being opened
	158	* @tty: the tty device being bound
	159	* @filp: the file pointer of the opener
	160	*
	161	* Implement the core POSIX/SuS tty behaviour when opening a tty device.
	162	* Handles:
	163	* - hangup (both before and during)
	164	* - non blocking open
	165	* - rts/dtr/dcd
	166	* - signals
	167	* - port flags and counts
	168	*
	169	* The passed tty_port must implement the carrier_raised method if it can
	170	* do carrier detect and the raise_dtr_rts method if it supports software
	171	* management of these lines. Note that the dtr/rts raise is done each
	172	* iteration as a hangup may have previously dropped them while we wait.
	173	*/
	174
	175	int tty_port_block_til_ready(struct tty_port *port,
	176	struct tty_struct tty, struct file filp)
	177	{
	178	int do_clocal = 0, retval;
	179	unsigned long flags;
	180	DECLARE_WAITQUEUE(wait, current);
	181	int cd;
	182
	183	/* block if port is in the process of being closed */
	184	if (tty_hung_up_p(filp) \|\| port->flags & ASYNC_CLOSING) {
	185	interruptible_sleep_on(&port->close_wait);
	186	if (port->flags & ASYNC_HUP_NOTIFY)
	187	return -EAGAIN;
	188	else
	189	return -ERESTARTSYS;
	190	}
	191
	192	/* if non-blocking mode is set we can pass directly to open unless
	193	the port has just hung up or is in another error state */
	194	if ((filp->f_flags & O_NONBLOCK) \|\|
	195	(tty->flags & (1 << TTY_IO_ERROR))) {
	196	port->flags \|= ASYNC_NORMAL_ACTIVE;
	197	return 0;
	198	}
	199
	200	if (C_CLOCAL(tty))
	201	do_clocal = 1;
	202
	203	/* Block waiting until we can proceed. We may need to wait for the
	204	carrier, but we must also wait for any close that is in progress
	205	before the next open may complete */
	206
	207	retval = 0;
	208	add_wait_queue(&port->open_wait, &wait);
	209
	210	/* The port lock protects the port counts */
	211	spin_lock_irqsave(&port->lock, flags);
	212	if (!tty_hung_up_p(filp))
	213	port->count--;
	214	port->blocked_open++;
	215	spin_unlock_irqrestore(&port->lock, flags);
	216
	217	while (1) {
218	/* Indicate we are open */
7834909f AC	219	if (tty->termios->c_cflag & CBAUD)
7834909f AC	220	tty_port_raise_dtr_rts(port);
36c621d8 AC	221
	222	set_current_state(TASK_INTERRUPTIBLE);
	223	/* Check for a hangup or uninitialised port. Return accordingly */
	224	if (tty_hung_up_p(filp) \|\| !(port->flags & ASYNC_INITIALIZED)) {
	225	if (port->flags & ASYNC_HUP_NOTIFY)
	226	retval = -EAGAIN;
	227	else
	228	retval = -ERESTARTSYS;
	229	break;
	230	}
	231	/* Probe the carrier. For devices with no carrier detect this
	232	will always return true */
	233	cd = tty_port_carrier_raised(port);
	234	if (!(port->flags & ASYNC_CLOSING) &&
	235	(do_clocal \|\| cd))
	236	break;
	237	if (signal_pending(current)) {
	238	retval = -ERESTARTSYS;
	239	break;
	240	}
	241	schedule();
	242	}
	243	set_current_state(TASK_RUNNING);
	244	remove_wait_queue(&port->open_wait, &wait);
	245
	246	/* Update counts. A parallel hangup will have set count to zero and
	247	we must not mess that up further */
	248	spin_lock_irqsave(&port->lock, flags);
	249	if (!tty_hung_up_p(filp))
	250	port->count++;
	251	port->blocked_open--;
	252	if (retval == 0)
	253	port->flags \|= ASYNC_NORMAL_ACTIVE;
	254	spin_unlock_irqrestore(&port->lock, flags);
	255	return 0;
	256
	257	}
	258	EXPORT_SYMBOL(tty_port_block_til_ready);
	259
a6614999 AC	260	int tty_port_close_start(struct tty_port port, struct tty_struct tty, struct file *filp)
	261	{
	262	unsigned long flags;
	263
	264	spin_lock_irqsave(&port->lock, flags);
	265	if (tty_hung_up_p(filp)) {
	266	spin_unlock_irqrestore(&port->lock, flags);
	267	return 0;
	268	}
	269
	270	if( tty->count == 1 && port->count != 1) {
	271	printk(KERN_WARNING
	272	"tty_port_close_start: tty->count = 1 port count = %d.\n",
	273	port->count);
	274	port->count = 1;
	275	}
	276	if (--port->count < 0) {
	277	printk(KERN_WARNING "tty_port_close_start: count = %d\n",
	278	port->count);
	279	port->count = 0;
	280	}
	281
	282	if (port->count) {
	283	spin_unlock_irqrestore(&port->lock, flags);
	284	return 0;
	285	}
	286	port->flags \|= ASYNC_CLOSING;
	287	tty->closing = 1;
	288	spin_unlock_irqrestore(&port->lock, flags);
fba85e01 AC	289	/* Don't block on a stalled port, just pull the chain */
	290	if (tty->flow_stopped)
	291	tty_driver_flush_buffer(tty);
6ed1dbae AC	292	if (port->flags & ASYNC_INITIALIZED &&
6ed1dbae AC	293	port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
a6614999 AC	294	tty_wait_until_sent(tty, port->closing_wait);
	295	return 1;
	296	}
	297	EXPORT_SYMBOL(tty_port_close_start);
	298
	299	void tty_port_close_end(struct tty_port port, struct tty_struct tty)
	300	{
	301	unsigned long flags;
	302
	303	tty_ldisc_flush(tty);
	304
	305	spin_lock_irqsave(&port->lock, flags);
	306	tty->closing = 0;
	307
	308	if (port->blocked_open) {
	309	spin_unlock_irqrestore(&port->lock, flags);
	310	if (port->close_delay) {
	311	msleep_interruptible(
	312	jiffies_to_msecs(port->close_delay));
	313	}
	314	spin_lock_irqsave(&port->lock, flags);
	315	wake_up_interruptible(&port->open_wait);
	316	}
	317	port->flags &= ~(ASYNC_NORMAL_ACTIVE \| ASYNC_CLOSING);
	318	wake_up_interruptible(&port->close_wait);
	319	spin_unlock_irqrestore(&port->lock, flags);
	320	}
	321	EXPORT_SYMBOL(tty_port_close_end);