timer.c

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/*
 *  Timers abstract layer
 *  Copyright (c) by Jaroslav Kysela <[email protected]>
 *
 *
 *   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 <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/module.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_HRTIMER) || defined(CONFIG_SND_HRTIMER_MODULE)
#define DEFAULT_TIMER_LIMIT 4
#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;
static int timer_tstamp_monotonic = 1;
MODULE_AUTHOR("Jaroslav Kysela <[email protected]>, Takashi Iwai <[email protected]>");
MODULE_DESCRIPTION("ALSA timer interface");
MODULE_LICENSE("GPL");
module_param(timer_limit, int, 0444);
MODULE_PARM_DESC(timer_limit, "Maximum global timers in system.");
module_param(timer_tstamp_monotonic, int, 0444);
MODULE_PARM_DESC(timer_tstamp_monotonic, "Use posix monotonic clock source for timestamps (default).");

MODULE_ALIAS_CHARDEV(CONFIG_SND_MAJOR, SNDRV_MINOR_TIMER);
MODULE_ALIAS("devname:snd/timer");

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_MODULES

static void snd_timer_request(struct snd_timer_id *tid)
{
    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_move_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_MODULES
    if (!timer) {
        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;

    if (snd_BUG_ON(!timeri))
        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;
        if (snd_BUG_ON(!timer))
            goto out;
        /* 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);
    }
 out:
    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;

    if (timer_tstamp_monotonic)
        do_posix_clock_monotonic_gettime(&tstamp);
    else
        getnstimeofday(&tstamp);
    if (snd_BUG_ON(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, event, &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_move_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;

    if (snd_BUG_ON(!timeri))
        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);
            if (timer->flags & SNDRV_TIMER_FLG_CHANGE) {
                timer->flags &= ~SNDRV_TIMER_FLG_CHANGE;
                timer->hw.start(timer);
            }
        }
    }
    if (!keep_flag)
        timeri->flags &=
            ~(SNDRV_TIMER_IFLG_RUNNING | SNDRV_TIMER_IFLG_START);
    spin_unlock_irqrestore(&timer->lock, flags);
      __end:
    if (event != SNDRV_TIMER_EVENT_RESOLUTION)
        snd_timer_notify1(timeri, event);
    return 0;
}

/*
 * stop the timer instance.
 *
 * do not call this from the timer callback!
 */
int snd_timer_stop(struct snd_timer_instance *timeri)
{
    struct snd_timer *timer;
    unsigned long flags;
    int err;

    err = _snd_timer_stop(timeri, 0, SNDRV_TIMER_EVENT_STOP);
    if (err < 0)
        return err;
    timer = timeri->timer;
    if (!timer)
        return -EINVAL;
    spin_lock_irqsave(&timer->lock, flags);
    timeri->cticks = timeri->ticks;
    timeri->pticks = 0;
    spin_unlock_irqrestore(&timer->lock, flags);
    return 0;
}

/*
 * start again..  the tick is kept.
 */
int snd_timer_continue(struct snd_timer_instance *timeri)
{
    struct snd_timer *timer;
    int result = -EINVAL;
    unsigned long flags;

    if (timeri == NULL)
        return result;
    if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
        return snd_timer_start_slave(timeri);
    timer = timeri->timer;
    if (! timer)
        return -EINVAL;
    spin_lock_irqsave(&timer->lock, flags);
    if (!timeri->cticks)
        timeri->cticks = 1;
    timeri->pticks = 0;
    result = snd_timer_start1(timer, timeri, timer->sticks);
    spin_unlock_irqrestore(&timer->lock, flags);
    snd_timer_notify1(timeri, SNDRV_TIMER_EVENT_CONTINUE);
    return result;
}

/*
 * pause.. remember the ticks left
 */
int snd_timer_pause(struct snd_timer_instance * timeri)
{
    return _snd_timer_stop(timeri, 0, SNDRV_TIMER_EVENT_PAUSE);
}

/*
 * reschedule the timer
 *
 * start pending instances and check the scheduling ticks.
 * when the scheduling ticks is changed set CHANGE flag to reprogram the timer.
 */
static void snd_timer_reschedule(struct snd_timer * timer, unsigned long ticks_left)
{
    struct snd_timer_instance *ti;
    unsigned long ticks = ~0UL;

    list_for_each_entry(ti, &timer->active_list_head, active_list) {
        if (ti->flags & SNDRV_TIMER_IFLG_START) {
            ti->flags &= ~SNDRV_TIMER_IFLG_START;
            ti->flags |= SNDRV_TIMER_IFLG_RUNNING;
            timer->running++;
        }
        if (ti->flags & SNDRV_TIMER_IFLG_RUNNING) {
            if (ticks > ti->cticks)
                ticks = ti->cticks;
        }
    }
    if (ticks == ~0UL) {
        timer->flags &= ~SNDRV_TIMER_FLG_RESCHED;
        return;
    }
    if (ticks > timer->hw.ticks)
        ticks = timer->hw.ticks;
    if (ticks_left != ticks)
        timer->flags |= SNDRV_TIMER_FLG_CHANGE;
    timer->sticks = ticks;
}

/*
 * timer tasklet
 *
 */
static void snd_timer_tasklet(unsigned long arg)
{
    struct snd_timer *timer = (struct snd_timer *) arg;
    struct snd_timer_instance *ti;
    struct list_head *p;
    unsigned long resolution, ticks;
    unsigned long flags;

    spin_lock_irqsave(&timer->lock, flags);
    /* now process all callbacks */
    while (!list_empty(&timer->sack_list_head)) {
        p = timer->sack_list_head.next;     /* get first item */
        ti = list_entry(p, struct snd_timer_instance, ack_list);

        /* remove from ack_list and make empty */
        list_del_init(p);

        ticks = ti->pticks;
        ti->pticks = 0;
        resolution = ti->resolution;

        ti->flags |= SNDRV_TIMER_IFLG_CALLBACK;
        spin_unlock(&timer->lock);
        if (ti->callback)
            ti->callback(ti, resolution, ticks);
        spin_lock(&timer->lock);
        ti->flags &= ~SNDRV_TIMER_IFLG_CALLBACK;
    }
    spin_unlock_irqrestore(&timer->lock, flags);
}

/*
 * timer interrupt
 *
 * ticks_left is usually equal to timer->sticks.
 *
 */
void snd_timer_interrupt(struct snd_timer * timer, unsigned long ticks_left)
{
    struct snd_timer_instance *ti, *ts, *tmp;
    unsigned long resolution, ticks;
    struct list_head *p, *ack_list_head;
    unsigned long flags;
    int use_tasklet = 0;

    if (timer == NULL)
        return;

    spin_lock_irqsave(&timer->lock, flags);

    /* remember the current resolution */
    if (timer->hw.c_resolution)
        resolution = timer->hw.c_resolution(timer);
    else
        resolution = timer->hw.resolution;

    /* loop for all active instances
     * Here we cannot use list_for_each_entry because the active_list of a
     * processed instance is relinked to done_list_head before the callback
     * is called.
     */
    list_for_each_entry_safe(ti, tmp, &timer->active_list_head,
                 active_list) {
        if (!(ti->flags & SNDRV_TIMER_IFLG_RUNNING))
            continue;
        ti->pticks += ticks_left;
        ti->resolution = resolution;
        if (ti->cticks < ticks_left)
            ti->cticks = 0;
        else
            ti->cticks -= ticks_left;
        if (ti->cticks) /* not expired */
            continue;
        if (ti->flags & SNDRV_TIMER_IFLG_AUTO) {
            ti->cticks = ti->ticks;
        } else {
            ti->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
            if (--timer->running)
                list_del(&ti->active_list);
        }
        if ((timer->hw.flags & SNDRV_TIMER_HW_TASKLET) ||
            (ti->flags & SNDRV_TIMER_IFLG_FAST))
            ack_list_head = &timer->ack_list_head;
        else
            ack_list_head = &timer->sack_list_head;
        if (list_empty(&ti->ack_list))
            list_add_tail(&ti->ack_list, ack_list_head);
        list_for_each_entry(ts, &ti->slave_active_head, active_list) {
            ts->pticks = ti->pticks;
            ts->resolution = resolution;
            if (list_empty(&ts->ack_list))
                list_add_tail(&ts->ack_list, ack_list_head);
        }
    }
    if (timer->flags & SNDRV_TIMER_FLG_RESCHED)
        snd_timer_reschedule(timer, timer->sticks);
    if (timer->running) {
        if (timer->hw.flags & SNDRV_TIMER_HW_STOP) {
            timer->hw.stop(timer);
            timer->flags |= SNDRV_TIMER_FLG_CHANGE;
        }
        if (!(timer->hw.flags & SNDRV_TIMER_HW_AUTO) ||
            (timer->flags & SNDRV_TIMER_FLG_CHANGE)) {
            /* restart timer */
            timer->flags &= ~SNDRV_TIMER_FLG_CHANGE;
            timer->hw.start(timer);
        }
    } else {
        timer->hw.stop(timer);
    }

    /* now process all fast callbacks */
    while (!list_empty(&timer->ack_list_head)) {
        p = timer->ack_list_head.next;      /* get first item */
        ti = list_entry(p, struct snd_timer_instance, ack_list);

        /* remove from ack_list and make empty */
        list_del_init(p);

        ticks = ti->pticks;
        ti->pticks = 0;

        ti->flags |= SNDRV_TIMER_IFLG_CALLBACK;
        spin_unlock(&timer->lock);
        if (ti->callback)
            ti->callback(ti, resolution, ticks);
        spin_lock(&timer->lock);
        ti->flags &= ~SNDRV_TIMER_IFLG_CALLBACK;
    }

    /* do we have any slow callbacks? */
    use_tasklet = !list_empty(&timer->sack_list_head);
    spin_unlock_irqrestore(&timer->lock, flags);

    if (use_tasklet)
        tasklet_schedule(&timer->task_queue);
}

/*

 */

int snd_timer_new(struct snd_card *card, char *id, struct snd_timer_id *tid,
          struct snd_timer **rtimer)
{
    struct snd_timer *timer;
    int err;
    static struct snd_device_ops ops = {
        .dev_free = snd_timer_dev_free,
        .dev_register = snd_timer_dev_register,
        .dev_disconnect = snd_timer_dev_disconnect,
    };

    if (snd_BUG_ON(!tid))
        return -EINVAL;
    if (rtimer)
        *rtimer = NULL;
    timer = kzalloc(sizeof(*timer), GFP_KERNEL);
    if (timer == NULL) {
        snd_printk(KERN_ERR "timer: cannot allocate\n");
        return -ENOMEM;
    }
    timer->tmr_class = tid->dev_class;
    timer->card = card;
    timer->tmr_device = tid->device;
    timer->tmr_subdevice = tid->subdevice;
    if (id)
        strlcpy(timer->id, id, sizeof(timer->id));
    INIT_LIST_HEAD(&timer->device_list);
    INIT_LIST_HEAD(&timer->open_list_head);
    INIT_LIST_HEAD(&timer->active_list_head);
    INIT_LIST_HEAD(&timer->ack_list_head);
    INIT_LIST_HEAD(&timer->sack_list_head);
    spin_lock_init(&timer->lock);
    tasklet_init(&timer->task_queue, snd_timer_tasklet,
             (unsigned long)timer);
    if (card != NULL) {
        timer->module = card->module;
        err = snd_device_new(card, SNDRV_DEV_TIMER, timer, &ops);
        if (err < 0) {
            snd_timer_free(timer);
            return err;
        }
    }
    if (rtimer)
        *rtimer = timer;
    return 0;
}

static int snd_timer_free(struct snd_timer *timer)
{
    if (!timer)
        return 0;

    mutex_lock(&register_mutex);
    if (! list_empty(&timer->open_list_head)) {
        struct list_head *p, *n;
        struct snd_timer_instance *ti;
        snd_printk(KERN_WARNING "timer %p is busy?\n", timer);
        list_for_each_safe(p, n, &timer->open_list_head) {
            list_del_init(p);
            ti = list_entry(p, struct snd_timer_instance, open_list);
            ti->timer = NULL;
        }
    }
    list_del(&timer->device_list);
    mutex_unlock(&register_mutex);

    if (timer->private_free)
        timer->private_free(timer);
    kfree(timer);
    return 0;
}

static int snd_timer_dev_free(struct snd_device *device)
{
    struct snd_timer *timer = device->device_data;
    return snd_timer_free(timer);
}

static int snd_timer_dev_register(struct snd_device *dev)
{
    struct snd_timer *timer = dev->device_data;
    struct snd_timer *timer1;

    if (snd_BUG_ON(!timer || !timer->hw.start || !timer->hw.stop))
        return -ENXIO;
    if (!(timer->hw.flags & SNDRV_TIMER_HW_SLAVE) &&
        !timer->hw.resolution && timer->hw.c_resolution == NULL)
            return -EINVAL;

    mutex_lock(&register_mutex);
    list_for_each_entry(timer1, &snd_timer_list, device_list) {
        if (timer1->tmr_class > timer->tmr_class)
            break;
        if (timer1->tmr_class < timer->tmr_class)
            continue;
        if (timer1->card && timer->card) {
            if (timer1->card->number > timer->card->number)
                break;
            if (timer1->card->number < timer->card->number)
                continue;
        }
        if (timer1->tmr_device > timer->tmr_device)
            break;
        if (timer1->tmr_device < timer->tmr_device)
            continue;
        if (timer1->tmr_subdevice > timer->tmr_subdevice)
            break;
        if (timer1->tmr_subdevice < timer->tmr_subdevice)
            continue;
        /* conflicts.. */
        mutex_unlock(&register_mutex);
        return -EBUSY;
    }
    list_add_tail(&timer->device_list, &timer1->device_list);
    mutex_unlock(&register_mutex);
    return 0;
}

static int snd_timer_dev_disconnect(struct snd_device *device)
{
    struct snd_timer *timer = device->device_data;
    mutex_lock(&register_mutex);
    list_del_init(&timer->device_list);
    mutex_unlock(&register_mutex);
    return 0;
}

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

    if (! (timer->hw.flags & SNDRV_TIMER_HW_SLAVE))
        return;
    if (snd_BUG_ON(event < SNDRV_TIMER_EVENT_MSTART ||
               event > SNDRV_TIMER_EVENT_MRESUME))
        return;
    spin_lock_irqsave(&timer->lock, flags);
    if (event == SNDRV_TIMER_EVENT_MSTART ||
        event == SNDRV_TIMER_EVENT_MCONTINUE ||
        event == SNDRV_TIMER_EVENT_MRESUME) {
        if (timer->hw.c_resolution)
            resolution = timer->hw.c_resolution(timer);
        else
            resolution = timer->hw.resolution;
    }
    list_for_each_entry(ti, &timer->active_list_head, active_list) {
        if (ti->ccallback)
            ti->ccallback(ti, event, tstamp, resolution);
        list_for_each_entry(ts, &ti->slave_active_head, active_list)
            if (ts->ccallback)
                ts->ccallback(ts, event, tstamp, resolution);
    }
    spin_unlock_irqrestore(&timer->lock, flags);
}

/*
 * exported functions for global timers
 */
int snd_timer_global_new(char *id, int device, struct snd_timer **rtimer)
{
    struct snd_timer_id tid;

    tid.dev_class = SNDRV_TIMER_CLASS_GLOBAL;
    tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
    tid.card = -1;
    tid.device = device;
    tid.subdevice = 0;
    return snd_timer_new(NULL, id, &tid, rtimer);
}

int snd_timer_global_free(struct snd_timer *timer)
{
    return snd_timer_free(timer);
}

int snd_timer_global_register(struct snd_timer *timer)
{
    struct snd_device dev;

    memset(&dev, 0, sizeof(dev));
    dev.device_data = timer;
    return snd_timer_dev_register(&dev);
}

/*
 *  System timer
 */

struct snd_timer_system_private {
    struct timer_list tlist;
    unsigned long last_expires;
    unsigned long last_jiffies;
    unsigned long correction;
};

static void snd_timer_s_function(unsigned long data)
{
    struct snd_timer *timer = (struct snd_timer *)data;
    struct snd_timer_system_private *priv = timer->private_data;
    unsigned long jiff = jiffies;
    if (time_after(jiff, priv->last_expires))
        priv->correction += (long)jiff - (long)priv->last_expires;
    snd_timer_interrupt(timer, (long)jiff - (long)priv->last_jiffies);
}

static int snd_timer_s_start(struct snd_timer * timer)
{
    struct snd_timer_system_private *priv;
    unsigned long njiff;

    priv = (struct snd_timer_system_private *) timer->private_data;
    njiff = (priv->last_jiffies = jiffies);
    if (priv->correction > timer->sticks - 1) {
        priv->correction -= timer->sticks - 1;
        njiff++;
    } else {
        njiff += timer->sticks - priv->correction;
        priv->correction = 0;
    }
    priv->last_expires = priv->tlist.expires = njiff;
    add_timer(&priv->tlist);
    return 0;
}

static int snd_timer_s_stop(struct snd_timer * timer)
{
    struct snd_timer_system_private *priv;
    unsigned long jiff;

    priv = (struct snd_timer_system_private *) timer->private_data;
    del_timer(&priv->tlist);
    jiff = jiffies;
    if (time_before(jiff, priv->last_expires))
        timer->sticks = priv->last_expires - jiff;
    else
        timer->sticks = 1;
    priv->correction = 0;
    return 0;
}

static struct snd_timer_hardware snd_timer_system =
{
    .flags =    SNDRV_TIMER_HW_FIRST | SNDRV_TIMER_HW_TASKLET,
    .resolution =   1000000000L / HZ,
    .ticks =    10000000L,
    .start =    snd_timer_s_start,
    .stop =     snd_timer_s_stop
};

static void snd_timer_free_system(struct snd_timer *timer)
{
    kfree(timer->private_data);
}

static int snd_timer_register_system(void)
{
    struct snd_timer *timer;
    struct snd_timer_system_private *priv;
    int err;

    err = snd_timer_global_new("system", SNDRV_TIMER_GLOBAL_SYSTEM, &timer);
    if (err < 0)
        return err;
    strcpy(timer->name, "system timer");
    timer->hw = snd_timer_system;
    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (priv == NULL) {
        snd_timer_free(timer);
        return -ENOMEM;
    }
    init_timer(&priv->tlist);
    priv->tlist.function = snd_timer_s_function;
    priv->tlist.data = (unsigned long) timer;
    timer->private_data = priv;
    timer->private_free = snd_timer_free_system;
    return snd_timer_global_register(timer);
}

#ifdef CONFIG_PROC_FS
/*
 *  Info interface
 */

static void snd_timer_proc_read(struct snd_info_entry *entry,
                struct snd_info_buffer *buffer)
{
    struct snd_timer *timer;
    struct snd_timer_instance *ti;

    mutex_lock(&register_mutex);
    list_for_each_entry(timer, &snd_timer_list, device_list) {
        switch (timer->tmr_class) {
        case SNDRV_TIMER_CLASS_GLOBAL:
            snd_iprintf(buffer, "G%i: ", timer->tmr_device);
            break;
        case SNDRV_TIMER_CLASS_CARD:
            snd_iprintf(buffer, "C%i-%i: ",
                    timer->card->number, timer->tmr_device);
            break;
        case SNDRV_TIMER_CLASS_PCM:
            snd_iprintf(buffer, "P%i-%i-%i: ", timer->card->number,
                    timer->tmr_device, timer->tmr_subdevice);
            break;
        default:
            snd_iprintf(buffer, "?%i-%i-%i-%i: ", timer->tmr_class,
                    timer->card ? timer->card->number : -1,
                    timer->tmr_device, timer->tmr_subdevice);
        }
        snd_iprintf(buffer, "%s :", timer->name);
        if (timer->hw.resolution)
            snd_iprintf(buffer, " %lu.%03luus (%lu ticks)",
                    timer->hw.resolution / 1000,
                    timer->hw.resolution % 1000,
                    timer->hw.ticks);
        if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
            snd_iprintf(buffer, " SLAVE");
        snd_iprintf(buffer, "\n");
        list_for_each_entry(ti, &timer->open_list_head, open_list)
            snd_iprintf(buffer, "  Client %s : %s\n",
                    ti->owner ? ti->owner : "unknown",
                    ti->flags & (SNDRV_TIMER_IFLG_START |
                         SNDRV_TIMER_IFLG_RUNNING)
                    ? "running" : "stopped");
    }
    mutex_unlock(&register_mutex);
}

static struct snd_info_entry *snd_timer_proc_entry;

static void __init snd_timer_proc_init(void)
{
    struct snd_info_entry *entry;

    entry = snd_info_create_module_entry(THIS_MODULE, "timers", NULL);
    if (entry != NULL) {
        entry->c.text.read = snd_timer_proc_read;
        if (snd_info_register(entry) < 0) {
            snd_info_free_entry(entry);
            entry = NULL;
        }
    }
    snd_timer_proc_entry = entry;
}

static void __exit snd_timer_proc_done(void)
{
    snd_info_free_entry(snd_timer_proc_entry);
}
#else /* !CONFIG_PROC_FS */
#define snd_timer_proc_init()
#define snd_timer_proc_done()
#endif

/*
 *  USER SPACE interface
 */

static void snd_timer_user_interrupt(struct snd_timer_instance *timeri,
                     unsigned long resolution,
                     unsigned long ticks)
{
    struct snd_timer_user *tu = timeri->callback_data;
    struct snd_timer_read *r;
    int prev;

    spin_lock(&tu->qlock);
    if (tu->qused > 0) {
        prev = tu->qtail == 0 ? tu->queue_size - 1 : tu->qtail - 1;
        r = &tu->queue[prev];
        if (r->resolution == resolution) {
            r->ticks += ticks;
            goto __wake;
        }
    }
    if (tu->qused >= tu->queue_size) {
        tu->overrun++;
    } else {
        r = &tu->queue[tu->qtail++];
        tu->qtail %= tu->queue_size;
        r->resolution = resolution;
        r->ticks = ticks;
        tu->qused++;
    }
      __wake:
    spin_unlock(&tu->qlock);
    kill_fasync(&tu->fasync, SIGIO, POLL_IN);
    wake_up(&tu->qchange_sleep);
}

static void snd_timer_user_append_to_tqueue(struct snd_timer_user *tu,
                        struct snd_timer_tread *tread)
{
    if (tu->qused >= tu->queue_size) {
        tu->overrun++;
    } else {
        memcpy(&tu->tqueue[tu->qtail++], tread, sizeof(*tread));
        tu->qtail %= tu->queue_size;
        tu->qused++;
    }
}

static void snd_timer_user_ccallback(struct snd_timer_instance *timeri,
                     int event,
                     struct timespec *tstamp,
                     unsigned long resolution)
{
    struct snd_timer_user *tu = timeri->callback_data;
    struct snd_timer_tread r1;
    unsigned long flags;

    if (event >= SNDRV_TIMER_EVENT_START &&
        event <= SNDRV_TIMER_EVENT_PAUSE)
        tu->tstamp = *tstamp;
    if ((tu->filter & (1 << event)) == 0 || !tu->tread)
        return;
    r1.event = event;
    r1.tstamp = *tstamp;
    r1.val = resolution;
    spin_lock_irqsave(&tu->qlock, flags);
    snd_timer_user_append_to_tqueue(tu, &r1);
    spin_unlock_irqrestore(&tu->qlock, flags);
    kill_fasync(&tu->fasync, SIGIO, POLL_IN);
    wake_up(&tu->qchange_sleep);
}

static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
                      unsigned long resolution,
                      unsigned long ticks)
{
    struct snd_timer_user *tu = timeri->callback_data;
    struct snd_timer_tread *r, r1;
    struct timespec tstamp;
    int prev, append = 0;

    memset(&tstamp, 0, sizeof(tstamp));
    spin_lock(&tu->qlock);
    if ((tu->filter & ((1 << SNDRV_TIMER_EVENT_RESOLUTION) |
               (1 << SNDRV_TIMER_EVENT_TICK))) == 0) {
        spin_unlock(&tu->qlock);
        return;
    }
    if (tu->last_resolution != resolution || ticks > 0) {
        if (timer_tstamp_monotonic)
            do_posix_clock_monotonic_gettime(&tstamp);
        else
            getnstimeofday(&tstamp);
    }
    if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) &&
        tu->last_resolution != resolution) {
        r1.event = SNDRV_TIMER_EVENT_RESOLUTION;
        r1.tstamp = tstamp;
        r1.val = resolution;
        snd_timer_user_append_to_tqueue(tu, &r1);
        tu->last_resolution = resolution;
        append++;
    }
    if ((tu->filter & (1 << SNDRV_TIMER_EVENT_TICK)) == 0)
        goto __wake;
    if (ticks == 0)
        goto __wake;
    if (tu->qused > 0) {
        prev = tu->qtail == 0 ? tu->queue_size - 1 : tu->qtail - 1;
        r = &tu->tqueue[prev];
        if (r->event == SNDRV_TIMER_EVENT_TICK) {
            r->tstamp = tstamp;
            r->val += ticks;
            append++;
            goto __wake;
        }
    }
    r1.event = SNDRV_TIMER_EVENT_TICK;
    r1.tstamp = tstamp;
    r1.val = ticks;
    snd_timer_user_append_to_tqueue(tu, &r1);
    append++;
      __wake:
    spin_unlock(&tu->qlock);
    if (append == 0)
        return;
    kill_fasync(&tu->fasync, SIGIO, POLL_IN);
    wake_up(&tu->qchange_sleep);
}

static int snd_timer_user_open(struct inode *inode, struct file *file)
{
    struct snd_timer_user *tu;
    int err;

    err = nonseekable_open(inode, file);
    if (err < 0)
        return err;

    tu = kzalloc(sizeof(*tu), GFP_KERNEL);
    if (tu == NULL)
        return -ENOMEM;
    spin_lock_init(&tu->qlock);
    init_waitqueue_head(&tu->qchange_sleep);
    mutex_init(&tu->tread_sem);
    tu->ticks = 1;
    tu->queue_size = 128;
    tu->queue = kmalloc(tu->queue_size * sizeof(struct snd_timer_read),
                GFP_KERNEL);
    if (tu->queue == NULL) {
        kfree(tu);
        return -ENOMEM;
    }
    file->private_data = tu;
    return 0;
}

static int snd_timer_user_release(struct inode *inode, struct file *file)
{
    struct snd_timer_user *tu;

    if (file->private_data) {
        tu = file->private_data;
        file->private_data = NULL;
        if (tu->timeri)
            snd_timer_close(tu->timeri);
        kfree(tu->queue);
        kfree(tu->tqueue);
        kfree(tu);
    }
    return 0;
}

static void snd_timer_user_zero_id(struct snd_timer_id *id)
{
    id->dev_class = SNDRV_TIMER_CLASS_NONE;
    id->dev_sclass = SNDRV_TIMER_SCLASS_NONE;
    id->card = -1;
    id->device = -1;
    id->subdevice = -1;
}

static void snd_timer_user_copy_id(struct snd_timer_id *id, struct snd_timer *timer)
{
    id->dev_class = timer->tmr_class;
    id->dev_sclass = SNDRV_TIMER_SCLASS_NONE;
    id->card = timer->card ? timer->card->number : -1;
    id->device = timer->tmr_device;
    id->subdevice = timer->tmr_subdevice;
}

static int snd_timer_user_next_device(struct snd_timer_id __user *_tid)
{
    struct snd_timer_id id;
    struct snd_timer *timer;
    struct list_head *p;

    if (copy_from_user(&id, _tid, sizeof(id)))
        return -EFAULT;
    mutex_lock(&register_mutex);
    if (id.dev_class < 0) {     /* first item */
        if (list_empty(&snd_timer_list))
            snd_timer_user_zero_id(&id);
        else {
            timer = list_entry(snd_timer_list.next,
                       struct snd_timer, device_list);
            snd_timer_user_copy_id(&id, timer);
        }
    } else {
        switch (id.dev_class) {
        case SNDRV_TIMER_CLASS_GLOBAL:
            id.device = id.device < 0 ? 0 : id.device + 1;
            list_for_each(p, &snd_timer_list) {
                timer = list_entry(p, struct snd_timer, device_list);
                if (timer->tmr_class > SNDRV_TIMER_CLASS_GLOBAL) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
                if (timer->tmr_device >= id.device) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
            }
            if (p == &snd_timer_list)
                snd_timer_user_zero_id(&id);
            break;
        case SNDRV_TIMER_CLASS_CARD:
        case SNDRV_TIMER_CLASS_PCM:
            if (id.card < 0) {
                id.card = 0;
            } else {
                if (id.card < 0) {
                    id.card = 0;
                } else {
                    if (id.device < 0) {
                        id.device = 0;
                    } else {
                        if (id.subdevice < 0) {
                            id.subdevice = 0;
                        } else {
                            id.subdevice++;
                        }
                    }
                }
            }
            list_for_each(p, &snd_timer_list) {
                timer = list_entry(p, struct snd_timer, device_list);
                if (timer->tmr_class > id.dev_class) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
                if (timer->tmr_class < id.dev_class)
                    continue;
                if (timer->card->number > id.card) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
                if (timer->card->number < id.card)
                    continue;
                if (timer->tmr_device > id.device) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
                if (timer->tmr_device < id.device)
                    continue;
                if (timer->tmr_subdevice > id.subdevice) {
                    snd_timer_user_copy_id(&id, timer);
                    break;
                }
                if (timer->tmr_subdevice < id.subdevice)
                    continue;
                snd_timer_user_copy_id(&id, timer);
                break;
            }
            if (p == &snd_timer_list)
                snd_timer_user_zero_id(&id);
            break;
        default:
            snd_timer_user_zero_id(&id);
        }
    }
    mutex_unlock(&register_mutex);
    if (copy_to_user(_tid, &id, sizeof(*_tid)))
        return -EFAULT;
    return 0;
}

static int snd_timer_user_ginfo(struct file *file,
                struct snd_timer_ginfo __user *_ginfo)
{
    struct snd_timer_ginfo *ginfo;
    struct snd_timer_id tid;
    struct snd_timer *t;
    struct list_head *p;
    int err = 0;

    ginfo = memdup_user(_ginfo, sizeof(*ginfo));
    if (IS_ERR(ginfo))
        return PTR_ERR(ginfo);

    tid = ginfo->tid;
    memset(ginfo, 0, sizeof(*ginfo));
    ginfo->tid = tid;
    mutex_lock(&register_mutex);
    t = snd_timer_find(&tid);
    if (t != NULL) {
        ginfo->card = t->card ? t->card->number : -1;
        if (t->hw.flags & SNDRV_TIMER_HW_SLAVE)
            ginfo->flags |= SNDRV_TIMER_FLG_SLAVE;
        strlcpy(ginfo->id, t->id, sizeof(ginfo->id));
        strlcpy(ginfo->name, t->name, sizeof(ginfo->name));
        ginfo->resolution = t->hw.resolution;
        if (t->hw.resolution_min > 0) {
            ginfo->resolution_min = t->hw.resolution_min;
            ginfo->resolution_max = t->hw.resolution_max;
        }
        list_for_each(p, &t->open_list_head) {
            ginfo->clients++;
        }
    } else {
        err = -ENODEV;
    }
    mutex_unlock(&register_mutex);
    if (err >= 0 && copy_to_user(_ginfo, ginfo, sizeof(*ginfo)))
        err = -EFAULT;
    kfree(ginfo);
    return err;
}

static int snd_timer_user_gparams(struct file *file,
                  struct snd_timer_gparams __user *_gparams)
{
    struct snd_timer_gparams gparams;
    struct snd_timer *t;
    int err;

    if (copy_from_user(&gparams, _gparams, sizeof(gparams)))
        return -EFAULT;
    mutex_lock(&register_mutex);
    t = snd_timer_find(&gparams.tid);
    if (!t) {
        err = -ENODEV;
        goto _error;
    }
    if (!list_empty(&t->open_list_head)) {
        err = -EBUSY;
        goto _error;
    }
    if (!t->hw.set_period) {
        err = -ENOSYS;
        goto _error;
    }
    err = t->hw.set_period(t, gparams.period_num, gparams.period_den);
_error:
    mutex_unlock(&register_mutex);
    return err;
}

static int snd_timer_user_gstatus(struct file *file,
                  struct snd_timer_gstatus __user *_gstatus)
{
    struct snd_timer_gstatus gstatus;
    struct snd_timer_id tid;
    struct snd_timer *t;
    int err = 0;

    if (copy_from_user(&gstatus, _gstatus, sizeof(gstatus)))
        return -EFAULT;
    tid = gstatus.tid;
    memset(&gstatus, 0, sizeof(gstatus));
    gstatus.tid = tid;
    mutex_lock(&register_mutex);
    t = snd_timer_find(&tid);
    if (t != NULL) {
        if (t->hw.c_resolution)
            gstatus.resolution = t->hw.c_resolution(t);
        else
            gstatus.resolution = t->hw.resolution;
        if (t->hw.precise_resolution) {
            t->hw.precise_resolution(t, &gstatus.resolution_num,
                         &gstatus.resolution_den);
        } else {
            gstatus.resolution_num = gstatus.resolution;
            gstatus.resolution_den = 1000000000uL;
        }
    } else {
        err = -ENODEV;
    }
    mutex_unlock(&register_mutex);
    if (err >= 0 && copy_to_user(_gstatus, &gstatus, sizeof(gstatus)))
        err = -EFAULT;
    return err;
}

static int snd_timer_user_tselect(struct file *file,
                  struct snd_timer_select __user *_tselect)
{
    struct snd_timer_user *tu;
    struct snd_timer_select tselect;
    char str[32];
    int err = 0;

    tu = file->private_data;
    mutex_lock(&tu->tread_sem);
    if (tu->timeri) {
        snd_timer_close(tu->timeri);
        tu->timeri = NULL;
    }
    if (copy_from_user(&tselect, _tselect, sizeof(tselect))) {
        err = -EFAULT;
        goto __err;
    }
    sprintf(str, "application %i", current->pid);
    if (tselect.id.dev_class != SNDRV_TIMER_CLASS_SLAVE)
        tselect.id.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION;
    err = snd_timer_open(&tu->timeri, str, &tselect.id, current->pid);
    if (err < 0)
        goto __err;

    kfree(tu->queue);
    tu->queue = NULL;
    kfree(tu->tqueue);
    tu->tqueue = NULL;
    if (tu->tread) {
        tu->tqueue = kmalloc(tu->queue_size * sizeof(struct snd_timer_tread),
                     GFP_KERNEL);
        if (tu->tqueue == NULL)
            err = -ENOMEM;
    } else {
        tu->queue = kmalloc(tu->queue_size * sizeof(struct snd_timer_read),
                    GFP_KERNEL);
        if (tu->queue == NULL)
            err = -ENOMEM;
    }

        if (err < 0) {
        snd_timer_close(tu->timeri);
            tu->timeri = NULL;
        } else {
        tu->timeri->flags |= SNDRV_TIMER_IFLG_FAST;
        tu->timeri->callback = tu->tread
            ? snd_timer_user_tinterrupt : snd_timer_user_interrupt;
        tu->timeri->ccallback = snd_timer_user_ccallback;
        tu->timeri->callback_data = (void *)tu;
    }

      __err:
        mutex_unlock(&tu->tread_sem);
    return err;
}

static int snd_timer_user_info(struct file *file,
                   struct snd_timer_info __user *_info)
{
    struct snd_timer_user *tu;
    struct snd_timer_info *info;
    struct snd_timer *t;
    int err = 0;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    t = tu->timeri->timer;
    if (!t)
        return -EBADFD;

    info = kzalloc(sizeof(*info), GFP_KERNEL);
    if (! info)
        return -ENOMEM;
    info->card = t->card ? t->card->number : -1;
    if (t->hw.flags & SNDRV_TIMER_HW_SLAVE)
        info->flags |= SNDRV_TIMER_FLG_SLAVE;
    strlcpy(info->id, t->id, sizeof(info->id));
    strlcpy(info->name, t->name, sizeof(info->name));
    info->resolution = t->hw.resolution;
    if (copy_to_user(_info, info, sizeof(*_info)))
        err = -EFAULT;
    kfree(info);
    return err;
}

static int snd_timer_user_params(struct file *file,
                 struct snd_timer_params __user *_params)
{
    struct snd_timer_user *tu;
    struct snd_timer_params params;
    struct snd_timer *t;
    struct snd_timer_read *tr;
    struct snd_timer_tread *ttr;
    int err;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    t = tu->timeri->timer;
    if (!t)
        return -EBADFD;
    if (copy_from_user(&params, _params, sizeof(params)))
        return -EFAULT;
    if (!(t->hw.flags & SNDRV_TIMER_HW_SLAVE) && params.ticks < 1) {
        err = -EINVAL;
        goto _end;
    }
    if (params.queue_size > 0 &&
        (params.queue_size < 32 || params.queue_size > 1024)) {
        err = -EINVAL;
        goto _end;
    }
    if (params.filter & ~((1<<SNDRV_TIMER_EVENT_RESOLUTION)|
                  (1<<SNDRV_TIMER_EVENT_TICK)|
                  (1<<SNDRV_TIMER_EVENT_START)|
                  (1<<SNDRV_TIMER_EVENT_STOP)|
                  (1<<SNDRV_TIMER_EVENT_CONTINUE)|
                  (1<<SNDRV_TIMER_EVENT_PAUSE)|
                  (1<<SNDRV_TIMER_EVENT_SUSPEND)|
                  (1<<SNDRV_TIMER_EVENT_RESUME)|
                  (1<<SNDRV_TIMER_EVENT_MSTART)|
                  (1<<SNDRV_TIMER_EVENT_MSTOP)|
                  (1<<SNDRV_TIMER_EVENT_MCONTINUE)|
                  (1<<SNDRV_TIMER_EVENT_MPAUSE)|
                  (1<<SNDRV_TIMER_EVENT_MSUSPEND)|
                  (1<<SNDRV_TIMER_EVENT_MRESUME))) {
        err = -EINVAL;
        goto _end;
    }
    snd_timer_stop(tu->timeri);
    spin_lock_irq(&t->lock);
    tu->timeri->flags &= ~(SNDRV_TIMER_IFLG_AUTO|
                   SNDRV_TIMER_IFLG_EXCLUSIVE|
                   SNDRV_TIMER_IFLG_EARLY_EVENT);
    if (params.flags & SNDRV_TIMER_PSFLG_AUTO)
        tu->timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
    if (params.flags & SNDRV_TIMER_PSFLG_EXCLUSIVE)
        tu->timeri->flags |= SNDRV_TIMER_IFLG_EXCLUSIVE;
    if (params.flags & SNDRV_TIMER_PSFLG_EARLY_EVENT)
        tu->timeri->flags |= SNDRV_TIMER_IFLG_EARLY_EVENT;
    spin_unlock_irq(&t->lock);
    if (params.queue_size > 0 &&
        (unsigned int)tu->queue_size != params.queue_size) {
        if (tu->tread) {
            ttr = kmalloc(params.queue_size * sizeof(*ttr),
                      GFP_KERNEL);
            if (ttr) {
                kfree(tu->tqueue);
                tu->queue_size = params.queue_size;
                tu->tqueue = ttr;
            }
        } else {
            tr = kmalloc(params.queue_size * sizeof(*tr),
                     GFP_KERNEL);
            if (tr) {
                kfree(tu->queue);
                tu->queue_size = params.queue_size;
                tu->queue = tr;
            }
        }
    }
    tu->qhead = tu->qtail = tu->qused = 0;
    if (tu->timeri->flags & SNDRV_TIMER_IFLG_EARLY_EVENT) {
        if (tu->tread) {
            struct snd_timer_tread tread;
            tread.event = SNDRV_TIMER_EVENT_EARLY;
            tread.tstamp.tv_sec = 0;
            tread.tstamp.tv_nsec = 0;
            tread.val = 0;
            snd_timer_user_append_to_tqueue(tu, &tread);
        } else {
            struct snd_timer_read *r = &tu->queue[0];
            r->resolution = 0;
            r->ticks = 0;
            tu->qused++;
            tu->qtail++;
        }
    }
    tu->filter = params.filter;
    tu->ticks = params.ticks;
    err = 0;
 _end:
    if (copy_to_user(_params, &params, sizeof(params)))
        return -EFAULT;
    return err;
}

static int snd_timer_user_status(struct file *file,
                 struct snd_timer_status __user *_status)
{
    struct snd_timer_user *tu;
    struct snd_timer_status status;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    memset(&status, 0, sizeof(status));
    status.tstamp = tu->tstamp;
    status.resolution = snd_timer_resolution(tu->timeri);
    status.lost = tu->timeri->lost;
    status.overrun = tu->overrun;
    spin_lock_irq(&tu->qlock);
    status.queue = tu->qused;
    spin_unlock_irq(&tu->qlock);
    if (copy_to_user(_status, &status, sizeof(status)))
        return -EFAULT;
    return 0;
}

static int snd_timer_user_start(struct file *file)
{
    int err;
    struct snd_timer_user *tu;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    snd_timer_stop(tu->timeri);
    tu->timeri->lost = 0;
    tu->last_resolution = 0;
    return (err = snd_timer_start(tu->timeri, tu->ticks)) < 0 ? err : 0;
}

static int snd_timer_user_stop(struct file *file)
{
    int err;
    struct snd_timer_user *tu;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    return (err = snd_timer_stop(tu->timeri)) < 0 ? err : 0;
}

static int snd_timer_user_continue(struct file *file)
{
    int err;
    struct snd_timer_user *tu;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    tu->timeri->lost = 0;
    return (err = snd_timer_continue(tu->timeri)) < 0 ? err : 0;
}

static int snd_timer_user_pause(struct file *file)
{
    int err;
    struct snd_timer_user *tu;

    tu = file->private_data;
    if (!tu->timeri)
        return -EBADFD;
    return (err = snd_timer_pause(tu->timeri)) < 0 ? err : 0;
}

enum {
    SNDRV_TIMER_IOCTL_START_OLD = _IO('T', 0x20),
    SNDRV_TIMER_IOCTL_STOP_OLD = _IO('T', 0x21),
    SNDRV_TIMER_IOCTL_CONTINUE_OLD = _IO('T', 0x22),
    SNDRV_TIMER_IOCTL_PAUSE_OLD = _IO('T', 0x23),
};

static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
                 unsigned long arg)
{
    struct snd_timer_user *tu;
    void __user *argp = (void __user *)arg;
    int __user *p = argp;

    tu = file->private_data;
    switch (cmd) {
    case SNDRV_TIMER_IOCTL_PVERSION:
        return put_user(SNDRV_TIMER_VERSION, p) ? -EFAULT : 0;
    case SNDRV_TIMER_IOCTL_NEXT_DEVICE:
        return snd_timer_user_next_device(argp);
    case SNDRV_TIMER_IOCTL_TREAD:
    {
        int xarg;

        mutex_lock(&tu->tread_sem);
        if (tu->timeri) {   /* too late */
            mutex_unlock(&tu->tread_sem);
            return -EBUSY;
        }
        if (get_user(xarg, p)) {
            mutex_unlock(&tu->tread_sem);
            return -EFAULT;
        }
        tu->tread = xarg ? 1 : 0;
        mutex_unlock(&tu->tread_sem);
        return 0;
    }
    case SNDRV_TIMER_IOCTL_GINFO:
        return snd_timer_user_ginfo(file, argp);
    case SNDRV_TIMER_IOCTL_GPARAMS:
        return snd_timer_user_gparams(file, argp);
    case SNDRV_TIMER_IOCTL_GSTATUS:
        return snd_timer_user_gstatus(file, argp);
    case SNDRV_TIMER_IOCTL_SELECT:
        return snd_timer_user_tselect(file, argp);
    case SNDRV_TIMER_IOCTL_INFO:
        return snd_timer_user_info(file, argp);
    case SNDRV_TIMER_IOCTL_PARAMS:
        return snd_timer_user_params(file, argp);
    case SNDRV_TIMER_IOCTL_STATUS:
        return snd_timer_user_status(file, argp);
    case SNDRV_TIMER_IOCTL_START:
    case SNDRV_TIMER_IOCTL_START_OLD:
        return snd_timer_user_start(file);
    case SNDRV_TIMER_IOCTL_STOP:
    case SNDRV_TIMER_IOCTL_STOP_OLD:
        return snd_timer_user_stop(file);
    case SNDRV_TIMER_IOCTL_CONTINUE:
    case SNDRV_TIMER_IOCTL_CONTINUE_OLD:
        return snd_timer_user_continue(file);
    case SNDRV_TIMER_IOCTL_PAUSE:
    case SNDRV_TIMER_IOCTL_PAUSE_OLD:
        return snd_timer_user_pause(file);
    }
    return -ENOTTY;
}

static int snd_timer_user_fasync(int fd, struct file * file, int on)
{
    struct snd_timer_user *tu;

    tu = file->private_data;
    return fasync_helper(fd, file, on, &tu->fasync);
}

static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
                   size_t count, loff_t *offset)
{
    struct snd_timer_user *tu;
    long result = 0, unit;
    int err = 0;

    tu = file->private_data;
    unit = tu->tread ? sizeof(struct snd_timer_tread) : sizeof(struct snd_timer_read);
    spin_lock_irq(&tu->qlock);
    while ((long)count - result >= unit) {
        while (!tu->qused) {
            wait_queue_t wait;

            if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
                err = -EAGAIN;
                break;
            }

            set_current_state(TASK_INTERRUPTIBLE);
            init_waitqueue_entry(&wait, current);
            add_wait_queue(&tu->qchange_sleep, &wait);

            spin_unlock_irq(&tu->qlock);
            schedule();
            spin_lock_irq(&tu->qlock);

            remove_wait_queue(&tu->qchange_sleep, &wait);

            if (signal_pending(current)) {
                err = -ERESTARTSYS;
                break;
            }
        }

        spin_unlock_irq(&tu->qlock);
        if (err < 0)
            goto _error;

        if (tu->tread) {
            if (copy_to_user(buffer, &tu->tqueue[tu->qhead++],
                     sizeof(struct snd_timer_tread))) {
                err = -EFAULT;
                goto _error;
            }
        } else {
            if (copy_to_user(buffer, &tu->queue[tu->qhead++],
                     sizeof(struct snd_timer_read))) {
                err = -EFAULT;
                goto _error;
            }
        }

        tu->qhead %= tu->queue_size;

        result += unit;
        buffer += unit;

        spin_lock_irq(&tu->qlock);
        tu->qused--;
    }
    spin_unlock_irq(&tu->qlock);
 _error:
    return result > 0 ? result : err;
}

static unsigned int snd_timer_user_poll(struct file *file, poll_table * wait)
{
        unsigned int mask;
        struct snd_timer_user *tu;

        tu = file->private_data;

        poll_wait(file, &tu->qchange_sleep, wait);

    mask = 0;
    if (tu->qused)
        mask |= POLLIN | POLLRDNORM;

    return mask;
}

#ifdef CONFIG_COMPAT
#include "timer_compat.c"
#else
#define snd_timer_user_ioctl_compat NULL
#endif

static const struct file_operations snd_timer_f_ops =
{
    .owner =    THIS_MODULE,
    .read =     snd_timer_user_read,
    .open =     snd_timer_user_open,
    .release =  snd_timer_user_release,
    .llseek =   no_llseek,
    .poll =     snd_timer_user_poll,
    .unlocked_ioctl =   snd_timer_user_ioctl,
    .compat_ioctl = snd_timer_user_ioctl_compat,
    .fasync =   snd_timer_user_fasync,
};

/*
 *  ENTRY functions
 */

static int __init alsa_timer_init(void)
{
    int err;

#ifdef SNDRV_OSS_INFO_DEV_TIMERS
    snd_oss_info_register(SNDRV_OSS_INFO_DEV_TIMERS, SNDRV_CARDS - 1,
                  "system timer");
#endif

    if ((err = snd_timer_register_system()) < 0)
        snd_printk(KERN_ERR "unable to register system timer (%i)\n",
               err);
    if ((err = snd_register_device(SNDRV_DEVICE_TYPE_TIMER, NULL, 0,
                       &snd_timer_f_ops, NULL, "timer")) < 0)
        snd_printk(KERN_ERR "unable to register timer device (%i)\n",
               err);
    snd_timer_proc_init();
    return 0;
}

static void __exit alsa_timer_exit(void)
{
    struct list_head *p, *n;

    snd_unregister_device(SNDRV_DEVICE_TYPE_TIMER, NULL, 0);
    /* unregister the system timer */
    list_for_each_safe(p, n, &snd_timer_list) {
        struct snd_timer *timer = list_entry(p, struct snd_timer, device_list);
        snd_timer_free(timer);
    }
    snd_timer_proc_done();
#ifdef SNDRV_OSS_INFO_DEV_TIMERS
    snd_oss_info_unregister(SNDRV_OSS_INFO_DEV_TIMERS, SNDRV_CARDS - 1);
#endif
}

module_init(alsa_timer_init)
module_exit(alsa_timer_exit)

EXPORT_SYMBOL(snd_timer_open);
EXPORT_SYMBOL(snd_timer_close);
EXPORT_SYMBOL(snd_timer_resolution);
EXPORT_SYMBOL(snd_timer_start);
EXPORT_SYMBOL(snd_timer_stop);
EXPORT_SYMBOL(snd_timer_continue);
EXPORT_SYMBOL(snd_timer_pause);
EXPORT_SYMBOL(snd_timer_new);
EXPORT_SYMBOL(snd_timer_notify);
EXPORT_SYMBOL(snd_timer_global_new);
EXPORT_SYMBOL(snd_timer_global_free);
EXPORT_SYMBOL(snd_timer_global_register);
EXPORT_SYMBOL(snd_timer_interrupt);