timer.c

linux 内核源代码

/*
 *  Timers abstract layer
 *  Copyright (c) by Jaroslav Kysela <[e-mail]>
 *
 *
 *   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 <sound/driver.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/moduleparam.h>
#include <linux/string.h>
#include <sound/core.h>
#include <sound/timer.h>
#include <sound/control.h>
#include <sound/info.h>
#include <sound/minors.h>
#include <sound/initval.h>
#include <linux/kmod.h>

#if defined(CONFIG_SND_HPET) || defined(CONFIG_SND_HPET_MODULE)
#define DEFAULT_TIMER_LIMIT 3
#elif defined(CONFIG_SND_RTCTIMER) || defined(CONFIG_SND_RTCTIMER_MODULE)
#define DEFAULT_TIMER_LIMIT 2
#else
#define DEFAULT_TIMER_LIMIT 1
#endif

static int timer_limit = DEFAULT_TIMER_LIMIT;
MODULE_AUTHOR("Jaroslav Kysela <[e-mail]>, Takashi Iwai <[e-mail]>");
MODULE_DESCRIPTION("ALSA timer interface");
MODULE_LICENSE("GPL");
module_param(timer_limit, int, 0444);
MODULE_PARM_DESC(timer_limit, "Maximum global timers in system.");

struct snd_timer_user {
	struct snd_timer_instance *timeri;
	int tread;		/* enhanced read with timestamps and events */
	unsigned long ticks;
	unsigned long overrun;
	int qhead;
	int qtail;
	int qused;
	int queue_size;
	struct snd_timer_read *queue;
	struct snd_timer_tread *tqueue;
	spinlock_t qlock;
	unsigned long last_resolution;
	unsigned int filter;
	struct timespec tstamp;		/* trigger tstamp */
	wait_queue_head_t qchange_sleep;
	struct fasync_struct *fasync;
	struct mutex tread_sem;
};

/* list of timers */
static LIST_HEAD(snd_timer_list);

/* list of slave instances */
static LIST_HEAD(snd_timer_slave_list);

/* lock for slave active lists */
static DEFINE_SPINLOCK(slave_active_lock);

static DEFINE_MUTEX(register_mutex);

static int snd_timer_free(struct snd_timer *timer);
static int snd_timer_dev_free(struct snd_device *device);
static int snd_timer_dev_register(struct snd_device *device);
static int snd_timer_dev_disconnect(struct snd_device *device);

static void snd_timer_reschedule(struct snd_timer * timer, unsigned long ticks_left);

/*
 * create a timer instance with the given owner string.
 * when timer is not NULL, increments the module counter
 */
static struct snd_timer_instance *snd_timer_instance_new(char *owner,
							 struct snd_timer *timer)
{
	struct snd_timer_instance *timeri;
	timeri = kzalloc(sizeof(*timeri), GFP_KERNEL);
	if (timeri == NULL)
		return NULL;
	timeri->owner = kstrdup(owner, GFP_KERNEL);
	if (! timeri->owner) {
		kfree(timeri);
		return NULL;
	}
	INIT_LIST_HEAD(&timeri->open_list);
	INIT_LIST_HEAD(&timeri->active_list);
	INIT_LIST_HEAD(&timeri->ack_list);
	INIT_LIST_HEAD(&timeri->slave_list_head);
	INIT_LIST_HEAD(&timeri->slave_active_head);

	timeri->timer = timer;
	if (timer && !try_module_get(timer->module)) {
		kfree(timeri->owner);
		kfree(timeri);
		return NULL;
	}

	return timeri;
}

/*
 * find a timer instance from the given timer id
 */
static struct snd_timer *snd_timer_find(struct snd_timer_id *tid)
{
	struct snd_timer *timer = NULL;

	list_for_each_entry(timer, &snd_timer_list, device_list) {
		if (timer->tmr_class != tid->dev_class)
			continue;
		if ((timer->tmr_class == SNDRV_TIMER_CLASS_CARD ||
		     timer->tmr_class == SNDRV_TIMER_CLASS_PCM) &&
		    (timer->card == NULL ||
		     timer->card->number != tid->card))
			continue;
		if (timer->tmr_device != tid->device)
			continue;
		if (timer->tmr_subdevice != tid->subdevice)
			continue;
		return timer;
	}
	return NULL;
}

#ifdef CONFIG_KMOD

static void snd_timer_request(struct snd_timer_id *tid)
{
	if (! current->fs->root)
		return;
	switch (tid->dev_class) {
	case SNDRV_TIMER_CLASS_GLOBAL:
		if (tid->device < timer_limit)
			request_module("snd-timer-%i", tid->device);
		break;
	case SNDRV_TIMER_CLASS_CARD:
	case SNDRV_TIMER_CLASS_PCM:
		if (tid->card < snd_ecards_limit)
			request_module("snd-card-%i", tid->card);
		break;
	default:
		break;
	}
}

#endif

/*
 * look for a master instance matching with the slave id of the given slave.
 * when found, relink the open_link of the slave.
 *
 * call this with register_mutex down.
 */
static void snd_timer_check_slave(struct snd_timer_instance *slave)
{
	struct snd_timer *timer;
	struct snd_timer_instance *master;

	/* FIXME: it's really dumb to look up all entries.. */
	list_for_each_entry(timer, &snd_timer_list, device_list) {
		list_for_each_entry(master, &timer->open_list_head, open_list) {
			if (slave->slave_class == master->slave_class &&
			    slave->slave_id == master->slave_id) {
				list_del(&slave->open_list);
				list_add_tail(&slave->open_list,
					      &master->slave_list_head);
				spin_lock_irq(&slave_active_lock);
				slave->master = master;
				slave->timer = master->timer;
				spin_unlock_irq(&slave_active_lock);
				return;
			}
		}
	}
}

/*
 * look for slave instances matching with the slave id of the given master.
 * when found, relink the open_link of slaves.
 *
 * call this with register_mutex down.
 */
static void snd_timer_check_master(struct snd_timer_instance *master)
{
	struct snd_timer_instance *slave, *tmp;

	/* check all pending slaves */
	list_for_each_entry_safe(slave, tmp, &snd_timer_slave_list, open_list) {
		if (slave->slave_class == master->slave_class &&
		    slave->slave_id == master->slave_id) {
			list_move_tail(&slave->open_list, &master->slave_list_head);
			spin_lock_irq(&slave_active_lock);
			slave->master = master;
			slave->timer = master->timer;
			if (slave->flags & SNDRV_TIMER_IFLG_RUNNING)
				list_add_tail(&slave->active_list,
					      &master->slave_active_head);
			spin_unlock_irq(&slave_active_lock);
		}
	}
}

/*
 * open a timer instance
 * when opening a master, the slave id must be here given.
 */
int snd_timer_open(struct snd_timer_instance **ti,
		   char *owner, struct snd_timer_id *tid,
		   unsigned int slave_id)
{
	struct snd_timer *timer;
	struct snd_timer_instance *timeri = NULL;

	if (tid->dev_class == SNDRV_TIMER_CLASS_SLAVE) {
		/* open a slave instance */
		if (tid->dev_sclass <= SNDRV_TIMER_SCLASS_NONE ||
		    tid->dev_sclass > SNDRV_TIMER_SCLASS_OSS_SEQUENCER) {
			snd_printd("invalid slave class %i\n", tid->dev_sclass);
			return -EINVAL;
		}
		mutex_lock(&register_mutex);
		timeri = snd_timer_instance_new(owner, NULL);
		if (!timeri) {
			mutex_unlock(&register_mutex);
			return -ENOMEM;
		}
		timeri->slave_class = tid->dev_sclass;
		timeri->slave_id = tid->device;
		timeri->flags |= SNDRV_TIMER_IFLG_SLAVE;
		list_add_tail(&timeri->open_list, &snd_timer_slave_list);
		snd_timer_check_slave(timeri);
		mutex_unlock(&register_mutex);
		*ti = timeri;
		return 0;
	}

	/* open a master instance */
	mutex_lock(&register_mutex);
	timer = snd_timer_find(tid);
#ifdef CONFIG_KMOD
	if (timer == NULL) {
		mutex_unlock(&register_mutex);
		snd_timer_request(tid);
		mutex_lock(&register_mutex);
		timer = snd_timer_find(tid);
	}
#endif
	if (!timer) {
		mutex_unlock(&register_mutex);
		return -ENODEV;
	}
	if (!list_empty(&timer->open_list_head)) {
		timeri = list_entry(timer->open_list_head.next,
				    struct snd_timer_instance, open_list);
		if (timeri->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
			mutex_unlock(&register_mutex);
			return -EBUSY;
		}
	}
	timeri = snd_timer_instance_new(owner, timer);
	if (!timeri) {
		mutex_unlock(&register_mutex);
		return -ENOMEM;
	}
	timeri->slave_class = tid->dev_sclass;
	timeri->slave_id = slave_id;
	if (list_empty(&timer->open_list_head) && timer->hw.open)
		timer->hw.open(timer);
	list_add_tail(&timeri->open_list, &timer->open_list_head);
	snd_timer_check_master(timeri);
	mutex_unlock(&register_mutex);
	*ti = timeri;
	return 0;
}

static int _snd_timer_stop(struct snd_timer_instance *timeri,
			   int keep_flag, int event);

/*
 * close a timer instance
 */
int snd_timer_close(struct snd_timer_instance *timeri)
{
	struct snd_timer *timer = NULL;
	struct snd_timer_instance *slave, *tmp;

	snd_assert(timeri != NULL, return -ENXIO);

	/* force to stop the timer */
	snd_timer_stop(timeri);

	if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
		/* wait, until the active callback is finished */
		spin_lock_irq(&slave_active_lock);
		while (timeri->flags & SNDRV_TIMER_IFLG_CALLBACK) {
			spin_unlock_irq(&slave_active_lock);
			udelay(10);
			spin_lock_irq(&slave_active_lock);
		}
		spin_unlock_irq(&slave_active_lock);
		mutex_lock(&register_mutex);
		list_del(&timeri->open_list);
		mutex_unlock(&register_mutex);
	} else {
		timer = timeri->timer;
		/* wait, until the active callback is finished */
		spin_lock_irq(&timer->lock);
		while (timeri->flags & SNDRV_TIMER_IFLG_CALLBACK) {
			spin_unlock_irq(&timer->lock);
			udelay(10);
			spin_lock_irq(&timer->lock);
		}
		spin_unlock_irq(&timer->lock);
		mutex_lock(&register_mutex);
		list_del(&timeri->open_list);
		if (timer && list_empty(&timer->open_list_head) &&
		    timer->hw.close)
			timer->hw.close(timer);
		/* remove slave links */
		list_for_each_entry_safe(slave, tmp, &timeri->slave_list_head,
					 open_list) {
			spin_lock_irq(&slave_active_lock);
			_snd_timer_stop(slave, 1, SNDRV_TIMER_EVENT_RESOLUTION);
			list_move_tail(&slave->open_list, &snd_timer_slave_list);
			slave->master = NULL;
			slave->timer = NULL;
			spin_unlock_irq(&slave_active_lock);
		}
		mutex_unlock(&register_mutex);
	}
	if (timeri->private_free)
		timeri->private_free(timeri);
	kfree(timeri->owner);
	kfree(timeri);
	if (timer)
		module_put(timer->module);
	return 0;
}

unsigned long snd_timer_resolution(struct snd_timer_instance *timeri)
{
	struct snd_timer * timer;

	if (timeri == NULL)
		return 0;
	if ((timer = timeri->timer) != NULL) {
		if (timer->hw.c_resolution)
			return timer->hw.c_resolution(timer);
		return timer->hw.resolution;
	}
	return 0;
}

static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
{
	struct snd_timer *timer;
	unsigned long flags;
	unsigned long resolution = 0;
	struct snd_timer_instance *ts;
	struct timespec tstamp;

	getnstimeofday(&tstamp);
	snd_assert(event >= SNDRV_TIMER_EVENT_START &&
		   event <= SNDRV_TIMER_EVENT_PAUSE, return);
	if (event == SNDRV_TIMER_EVENT_START ||
	    event == SNDRV_TIMER_EVENT_CONTINUE)
		resolution = snd_timer_resolution(ti);
	if (ti->ccallback)
		ti->ccallback(ti, SNDRV_TIMER_EVENT_START, &tstamp, resolution);
	if (ti->flags & SNDRV_TIMER_IFLG_SLAVE)
		return;
	timer = ti->timer;
	if (timer == NULL)
		return;
	if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
		return;
	spin_lock_irqsave(&timer->lock, flags);
	list_for_each_entry(ts, &ti->slave_active_head, active_list)
		if (ts->ccallback)
			ts->ccallback(ti, event + 100, &tstamp, resolution);
	spin_unlock_irqrestore(&timer->lock, flags);
}

static int snd_timer_start1(struct snd_timer *timer, struct snd_timer_instance *timeri,
			    unsigned long sticks)
{
	list_del(&timeri->active_list);
	list_add_tail(&timeri->active_list, &timer->active_list_head);
	if (timer->running) {
		if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
			goto __start_now;
		timer->flags |= SNDRV_TIMER_FLG_RESCHED;
		timeri->flags |= SNDRV_TIMER_IFLG_START;
		return 1;	/* delayed start */
	} else {
		timer->sticks = sticks;
		timer->hw.start(timer);
	      __start_now:
		timer->running++;
		timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
		return 0;
	}
}

static int snd_timer_start_slave(struct snd_timer_instance *timeri)
{
	unsigned long flags;

	spin_lock_irqsave(&slave_active_lock, flags);
	timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
	if (timeri->master)
		list_add_tail(&timeri->active_list,
			      &timeri->master->slave_active_head);
	spin_unlock_irqrestore(&slave_active_lock, flags);
	return 1; /* delayed start */
}

/*
 *  start the timer instance
 */
int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
{
	struct snd_timer *timer;
	int result = -EINVAL;
	unsigned long flags;

	if (timeri == NULL || ticks < 1)
		return -EINVAL;
	if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
		result = snd_timer_start_slave(timeri);
		snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
		return result;
	}
	timer = timeri->timer;
	if (timer == NULL)
		return -EINVAL;
	spin_lock_irqsave(&timer->lock, flags);
	timeri->ticks = timeri->cticks = ticks;
	timeri->pticks = 0;
	result = snd_timer_start1(timer, timeri, ticks);
	spin_unlock_irqrestore(&timer->lock, flags);
	snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_START);
	return result;
}

static int _snd_timer_stop(struct snd_timer_instance * timeri,
			   int keep_flag, int event)
{
	struct snd_timer *timer;
	unsigned long flags;

	snd_assert(timeri != NULL, return -ENXIO);

	if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE) {
		if (!keep_flag) {
			spin_lock_irqsave(&slave_active_lock, flags);
			timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
			spin_unlock_irqrestore(&slave_active_lock, flags);
		}
		goto __end;
	}
	timer = timeri->timer;
	if (!timer)
		return -EINVAL;
	spin_lock_irqsave(&timer->lock, flags);
	list_del_init(&timeri->ack_list);
	list_del_init(&timeri->active_list);
	if ((timeri->flags & SNDRV_TIMER_IFLG_RUNNING) &&
	    !(--timer->running)) {
		timer->hw.stop(timer);
		if (timer->flags & SNDRV_TIMER_FLG_RESCHED) {
			timer->flags &= ~SNDRV_TIMER_FLG_RESCHED;
			snd_timer_reschedule(timer, 0);