// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Timers abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
 */

#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 <linux/sched/signal.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>

/* internal flags */
#define SNDRV_TIMER_IFLG_PAUSED         0x00010000
#define SNDRV_TIMER_IFLG_DEAD           0x00020000

#if IS_ENABLED(CONFIG_SND_HRTIMER)
#define DEFAULT_TIMER_LIMIT 4
#else
#define DEFAULT_TIMER_LIMIT 1
#endif

static int timer_limit = DEFAULT_TIMER_LIMIT;
static int timer_tstamp_monotonic = 1;
MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>");
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");

enum timer_tread_format {
        TREAD_FORMAT_NONE = 0,
        TREAD_FORMAT_TIME64,
        TREAD_FORMAT_TIME32,
};

struct snd_timer_tread32 {
        int event;
        s32 tstamp_sec;
        s32 tstamp_nsec;
        unsigned int val;
};

struct snd_timer_tread64 {
        int event;
        u8 pad1[4];
        s64 tstamp_sec;
        s64 tstamp_nsec;
        unsigned int val;
        u8 pad2[4];
};

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;
        bool disconnected;
        struct snd_timer_read *queue;
        struct snd_timer_tread64 *tqueue;
        spinlock_t qlock;
        unsigned long last_resolution;
        unsigned int filter;
        struct timespec64 tstamp;               /* trigger tstamp */
        wait_queue_head_t qchange_sleep;
        struct fasync_struct *fasync;
        struct mutex ioctl_lock;
};

struct snd_timer_status32 {
        s32 tstamp_sec;                 /* Timestamp - last update */
        s32 tstamp_nsec;
        unsigned int resolution;        /* current period resolution in ns */
        unsigned int lost;              /* counter of master tick lost */
        unsigned int overrun;           /* count of read queue overruns */
        unsigned int queue;             /* used queue size */
        unsigned char reserved[64];     /* reserved */
};

#define SNDRV_TIMER_IOCTL_STATUS32      _IOR('T', 0x14, struct snd_timer_status32)

struct snd_timer_status64 {
        s64 tstamp_sec;                 /* Timestamp - last update */
        s64 tstamp_nsec;
        unsigned int resolution;        /* current period resolution in ns */
        unsigned int lost;              /* counter of master tick lost */
        unsigned int overrun;           /* count of read queue overruns */
        unsigned int queue;             /* used queue size */
        unsigned char reserved[64];     /* reserved */
};

#define SNDRV_TIMER_IOCTL_STATUS64      _IOR('T', 0x14, struct snd_timer_status64)

/* 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);

#define MAX_SLAVE_INSTANCES     1000
static int num_slaves;

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.
 */
struct snd_timer_instance *snd_timer_instance_new(const char *owner)
{
        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);

        return timeri;
}
EXPORT_SYMBOL(snd_timer_instance_new);

void snd_timer_instance_free(struct snd_timer_instance *timeri)
{
        if (timeri) {
                if (timeri->private_free)
                        timeri->private_free(timeri);
                kfree(timeri->owner);
                kfree(timeri);
        }
}
EXPORT_SYMBOL(snd_timer_instance_free);

/*
 * 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;

        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

/* move the slave if it belongs to the master; return 1 if match */
static int check_matching_master_slave(struct snd_timer_instance *master,
                                       struct snd_timer_instance *slave)
{
        if (slave->slave_class != master->slave_class ||
            slave->slave_id != master->slave_id)
                return 0;
        if (master->timer->num_instances >= master->timer->max_instances)
                return -EBUSY;
        list_move_tail(&slave->open_list, &master->slave_list_head);
        master->timer->num_instances++;
        spin_lock_irq(&slave_active_lock);
        spin_lock(&master->timer->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(&master->timer->lock);
        spin_unlock_irq(&slave_active_lock);
        return 1;
}

/*
 * 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 int snd_timer_check_slave(struct snd_timer_instance *slave)
{
        struct snd_timer *timer;
        struct snd_timer_instance *master;
        int err = 0;

        /* 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) {
                        err = check_matching_master_slave(master, slave);
                        if (err != 0) /* match found or error */
                                goto out;
                }
        }
 out:
        return err < 0 ? err : 0;
}

/*
 * 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 int snd_timer_check_master(struct snd_timer_instance *master)
{
        struct snd_timer_instance *slave, *tmp;
        int err = 0;

        /* check all pending slaves */
        list_for_each_entry_safe(slave, tmp, &snd_timer_slave_list, open_list) {
                err = check_matching_master_slave(master, slave);
                if (err < 0)
                        break;
        }
        return err < 0 ? err : 0;
}

static void snd_timer_close_locked(struct snd_timer_instance *timeri,
                                   struct device **card_devp_to_put);

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

        mutex_lock(&register_mutex);
        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) {
                        pr_debug("ALSA: timer: invalid slave class %i\n",
                                 tid->dev_sclass);
                        err = -EINVAL;
                        goto unlock;
                }
                if (num_slaves >= MAX_SLAVE_INSTANCES) {
                        err = -EBUSY;
                        goto unlock;
                }
                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);
                num_slaves++;
                err = snd_timer_check_slave(timeri);
                goto list_added;
        }

        /* open a master instance */
        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) {
                err = -ENODEV;
                goto unlock;
        }
        if (!list_empty(&timer->open_list_head)) {
                struct snd_timer_instance *t =
                        list_entry(timer->open_list_head.next,
                                    struct snd_timer_instance, open_list);
                if (t->flags & SNDRV_TIMER_IFLG_EXCLUSIVE) {
                        err = -EBUSY;
                        goto unlock;
                }
        }
        if (timer->num_instances >= timer->max_instances) {
                err = -EBUSY;
                goto unlock;
        }
        if (!try_module_get(timer->module)) {
                err = -EBUSY;
                goto unlock;
        }
        /* take a card refcount for safe disconnection */
        if (timer->card) {
                get_device(&timer->card->card_dev);
                card_dev_to_put = &timer->card->card_dev;
        }

        if (list_empty(&timer->open_list_head) && timer->hw.open) {
                err = timer->hw.open(timer);
                if (err) {
                        module_put(timer->module);
                        goto unlock;
                }
        }

        timeri->timer = timer;
        timeri->slave_class = tid->dev_sclass;
        timeri->slave_id = slave_id;

        list_add_tail(&timeri->open_list, &timer->open_list_head);
        timer->num_instances++;
        err = snd_timer_check_master(timeri);
list_added:
        if (err < 0)
                snd_timer_close_locked(timeri, &card_dev_to_put);

 unlock:
        mutex_unlock(&register_mutex);
        /* put_device() is called after unlock for avoiding deadlock */
        if (err < 0 && card_dev_to_put)
                put_device(card_dev_to_put);
        return err;
}
EXPORT_SYMBOL(snd_timer_open);

/*
 * close a timer instance
 * call this with register_mutex down.
 */
static void snd_timer_close_locked(struct snd_timer_instance *timeri,
                                   struct device **card_devp_to_put)
{
        struct snd_timer *timer = timeri->timer;
        struct snd_timer_instance *slave, *tmp;

        if (timer) {
                spin_lock_irq(&timer->lock);
                timeri->flags |= SNDRV_TIMER_IFLG_DEAD;
                spin_unlock_irq(&timer->lock);
        }

        if (!list_empty(&timeri->open_list)) {
                list_del_init(&timeri->open_list);
                if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                        num_slaves--;
        }

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

        if (timer) {
                timer->num_instances--;
                /* 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);

                /* remove slave links */
                spin_lock_irq(&slave_active_lock);
                spin_lock(&timer->lock);
                timeri->timer = NULL;
                list_for_each_entry_safe(slave, tmp, &timeri->slave_list_head,
                                         open_list) {
                        list_move_tail(&slave->open_list, &snd_timer_slave_list);
                        timer->num_instances--;
                        slave->master = NULL;
                        slave->timer = NULL;
                        list_del_init(&slave->ack_list);
                        list_del_init(&slave->active_list);
                }
                spin_unlock(&timer->lock);
                spin_unlock_irq(&slave_active_lock);

                /* slave doesn't need to release timer resources below */
                if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                        timer = NULL;
        }

        if (timer) {
                if (list_empty(&timer->open_list_head) && timer->hw.close)
                        timer->hw.close(timer);
                /* release a card refcount for safe disconnection */
                if (timer->card)
                        *card_devp_to_put = &timer->card->card_dev;
                module_put(timer->module);
        }
}

/*
 * close a timer instance
 */
void snd_timer_close(struct snd_timer_instance *timeri)
{
        struct device *card_dev_to_put = NULL;

        if (snd_BUG_ON(!timeri))
                return;

        mutex_lock(&register_mutex);
        snd_timer_close_locked(timeri, &card_dev_to_put);
        mutex_unlock(&register_mutex);
        /* put_device() is called after unlock for avoiding deadlock */
        if (card_dev_to_put)
                put_device(card_dev_to_put);
}
EXPORT_SYMBOL(snd_timer_close);

static unsigned long snd_timer_hw_resolution(struct snd_timer *timer)
{
        if (timer->hw.c_resolution)
                return timer->hw.c_resolution(timer);
        else
                return timer->hw.resolution;
}

unsigned long snd_timer_resolution(struct snd_timer_instance *timeri)
{
        struct snd_timer * timer;
        unsigned long ret = 0;
        unsigned long flags;

        if (timeri == NULL)
                return 0;
        timer = timeri->timer;
        if (timer) {
                spin_lock_irqsave(&timer->lock, flags);
                ret = snd_timer_hw_resolution(timer);
                spin_unlock_irqrestore(&timer->lock, flags);
        }
        return ret;
}
EXPORT_SYMBOL(snd_timer_resolution);

static void snd_timer_notify1(struct snd_timer_instance *ti, int event)
{
        struct snd_timer *timer = ti->timer;
        unsigned long resolution = 0;
        struct snd_timer_instance *ts;
        struct timespec64 tstamp;

        if (timer_tstamp_monotonic)
                ktime_get_ts64(&tstamp);
        else
                ktime_get_real_ts64(&tstamp);
        if (snd_BUG_ON(event < SNDRV_TIMER_EVENT_START ||
                       event > SNDRV_TIMER_EVENT_PAUSE))
                return;
        if (timer &&
            (event == SNDRV_TIMER_EVENT_START ||
             event == SNDRV_TIMER_EVENT_CONTINUE))
                resolution = snd_timer_hw_resolution(timer);
        if (ti->ccallback)
                ti->ccallback(ti, event, &tstamp, resolution);
        if (ti->flags & SNDRV_TIMER_IFLG_SLAVE)
                return;
        if (timer == NULL)
                return;
        if (timer->hw.flags & SNDRV_TIMER_HW_SLAVE)
                return;
        event += 10; /* convert to SNDRV_TIMER_EVENT_MXXX */
        list_for_each_entry(ts, &ti->slave_active_head, active_list)
                if (ts->ccallback)
                        ts->ccallback(ts, event, &tstamp, resolution);
}

/* start/continue a master timer */
static int snd_timer_start1(struct snd_timer_instance *timeri,
                            bool start, unsigned long ticks)
{
        struct snd_timer *timer;
        int result;
        unsigned long flags;

        timer = timeri->timer;
        if (!timer)
                return -EINVAL;

        spin_lock_irqsave(&timer->lock, flags);
        if (timeri->flags & SNDRV_TIMER_IFLG_DEAD) {
                result = -EINVAL;
                goto unlock;
        }
        if (timer->card && timer->card->shutdown) {
                result = -ENODEV;
                goto unlock;
        }
        if (timeri->flags & (SNDRV_TIMER_IFLG_RUNNING |
                             SNDRV_TIMER_IFLG_START)) {
                result = -EBUSY;
                goto unlock;
        }

        if (start)
                timeri->ticks = timeri->cticks = ticks;
        else if (!timeri->cticks)
                timeri->cticks = 1;
        timeri->pticks = 0;

        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;
                result = 1; /* delayed start */
        } else {
                if (start)
                        timer->sticks = ticks;
                timer->hw.start(timer);
              __start_now:
                timer->running++;
                timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
                result = 0;
        }
        snd_timer_notify1(timeri, start ? SNDRV_TIMER_EVENT_START :
                          SNDRV_TIMER_EVENT_CONTINUE);
 unlock:
        spin_unlock_irqrestore(&timer->lock, flags);
        return result;
}

/* start/continue a slave timer */
static int snd_timer_start_slave(struct snd_timer_instance *timeri,
                                 bool start)
{
        unsigned long flags;
        int err;

        spin_lock_irqsave(&slave_active_lock, flags);
        if (timeri->flags & SNDRV_TIMER_IFLG_DEAD) {
                err = -EINVAL;
                goto unlock;
        }
        if (timeri->flags & SNDRV_TIMER_IFLG_RUNNING) {
                err = -EBUSY;
                goto unlock;
        }
        timeri->flags |= SNDRV_TIMER_IFLG_RUNNING;
        if (timeri->master && timeri->timer) {
                spin_lock(&timeri->timer->lock);
                list_add_tail(&timeri->active_list,
                              &timeri->master->slave_active_head);
                snd_timer_notify1(timeri, start ? SNDRV_TIMER_EVENT_START :
                                  SNDRV_TIMER_EVENT_CONTINUE);
                spin_unlock(&timeri->timer->lock);
        }
        err = 1; /* delayed start */
 unlock:
        spin_unlock_irqrestore(&slave_active_lock, flags);
        return err;
}

/* stop/pause a master timer */
static int snd_timer_stop1(struct snd_timer_instance *timeri, bool stop)
{
        struct snd_timer *timer;
        int result = 0;
        unsigned long flags;

        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 |
                               SNDRV_TIMER_IFLG_START))) {
                result = -EBUSY;
                goto unlock;
        }
        if (timer->card && timer->card->shutdown)
                goto unlock;
        if (stop) {
                timeri->cticks = timeri->ticks;
                timeri->pticks = 0;
        }
        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);
                        }
                }
        }
        timeri->flags &= ~(SNDRV_TIMER_IFLG_RUNNING | SNDRV_TIMER_IFLG_START);
        if (stop)
                timeri->flags &= ~SNDRV_TIMER_IFLG_PAUSED;
        else
                timeri->flags |= SNDRV_TIMER_IFLG_PAUSED;
        snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP :
                          SNDRV_TIMER_EVENT_PAUSE);
 unlock:
        spin_unlock_irqrestore(&timer->lock, flags);
        return result;
}

/* stop/pause a slave timer */
static int snd_timer_stop_slave(struct snd_timer_instance *timeri, bool stop)
{
        unsigned long flags;
        bool running;

        spin_lock_irqsave(&slave_active_lock, flags);
        running = timeri->flags & SNDRV_TIMER_IFLG_RUNNING;
        timeri->flags &= ~SNDRV_TIMER_IFLG_RUNNING;
        if (timeri->timer) {
                spin_lock(&timeri->timer->lock);
                list_del_init(&timeri->ack_list);
                list_del_init(&timeri->active_list);
                if (running)
                        snd_timer_notify1(timeri, stop ? SNDRV_TIMER_EVENT_STOP :
                                          SNDRV_TIMER_EVENT_PAUSE);
                spin_unlock(&timeri->timer->lock);
        }
        spin_unlock_irqrestore(&slave_active_lock, flags);
        return running ? 0 : -EBUSY;
}

/*
 *  start the timer instance
 */
int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks)
{
        if (timeri == NULL || ticks < 1)
                return -EINVAL;
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                return snd_timer_start_slave(timeri, true);
        else
                return snd_timer_start1(timeri, true, ticks);
}
EXPORT_SYMBOL(snd_timer_start);

/*
 * stop the timer instance.
 *
 * do not call this from the timer callback!
 */
int snd_timer_stop(struct snd_timer_instance *timeri)
{
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                return snd_timer_stop_slave(timeri, true);
        else
                return snd_timer_stop1(timeri, true);
}
EXPORT_SYMBOL(snd_timer_stop);

/*
 * start again..  the tick is kept.
 */
int snd_timer_continue(struct snd_timer_instance *timeri)
{
        /* timer can continue only after pause */
        if (!(timeri->flags & SNDRV_TIMER_IFLG_PAUSED))
                return -EINVAL;

        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                return snd_timer_start_slave(timeri, false);
        else
                return snd_timer_start1(timeri, false, 0);
}
EXPORT_SYMBOL(snd_timer_continue);

/*
 * pause.. remember the ticks left
 */
int snd_timer_pause(struct snd_timer_instance * timeri)
{
        if (timeri->flags & SNDRV_TIMER_IFLG_SLAVE)
                return snd_timer_stop_slave(timeri, false);
        else
                return snd_timer_stop1(timeri, false);
}
EXPORT_SYMBOL(snd_timer_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;
}

/* call callbacks in timer ack list */
static void snd_timer_process_callbacks(struct snd_timer *timer,
                                        struct list_head *head)
{
        struct snd_timer_instance *ti;
        unsigned long resolution, ticks;

        while (!list_empty(head)) {
                ti = list_first_entry(head, struct snd_timer_instance,
                                      ack_list);

                /* remove from ack_list and make empty */
                list_del_init(&ti->ack_list);

                if (!(ti->flags & SNDRV_TIMER_IFLG_DEAD)) {
                        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;
                }
        }
}

/* clear pending instances from ack list */
static void snd_timer_clear_callbacks(struct snd_timer *timer,
                                      struct list_head *head)
{
        unsigned long flags;

        spin_lock_irqsave(&timer->lock, flags);
        while (!list_empty(head))
                list_del_init(head->next);
        spin_unlock_irqrestore(&timer->lock, flags);
}

/*
 * timer work
 *
 */
static void snd_timer_work(struct work_struct *work)
{
        struct snd_timer *timer = container_of(work, struct snd_timer, task_work);
        unsigned long flags;

        if (timer->card && timer->card->shutdown) {
                snd_timer_clear_callbacks(timer, &timer->sack_list_head);
                return;
        }

        spin_lock_irqsave(&timer->lock, flags);
        snd_timer_process_callbacks(timer, &timer->sack_list_head);
        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;
        struct list_head *ack_list_head;
        unsigned long flags;
        bool use_work = false;

        if (timer == NULL)
                return;

        if (timer->card && timer->card->shutdown) {
                snd_timer_clear_callbacks(timer, &timer->ack_list_head);
                return;
        }

        spin_lock_irqsave(&timer->lock, flags);

        /* remember the current resolution */
        resolution = snd_timer_hw_resolution(timer);

        /* 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_DEAD)
                        continue;
                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;
                        --timer->running;
                        list_del_init(&ti->active_list);
                }
                if ((timer->hw.flags & SNDRV_TIMER_HW_WORK) ||
                    (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 */
        snd_timer_process_callbacks(timer, &timer->ack_list_head);

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

        if (use_work)
                queue_work(system_highpri_wq, &timer->task_work);
}
EXPORT_SYMBOL(snd_timer_interrupt);

/*

 */

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 const 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 (tid->dev_class == SNDRV_TIMER_CLASS_CARD ||
            tid->dev_class == SNDRV_TIMER_CLASS_PCM) {
                if (WARN_ON(!card))
                        return -EINVAL;
        }
        if (rtimer)
                *rtimer = NULL;
        timer = kzalloc(sizeof(*timer), GFP_KERNEL);
        if (!timer)
                return -ENOMEM;
        timer->tmr_class = tid->dev_class;
        timer->card = card;
        timer->tmr_device = tid->device;
        timer->tmr_subdevice = tid->subdevice;
        if (id)
                strscpy(timer->id, id, sizeof(timer->id));
        timer->sticks = 1;
        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);
        INIT_WORK(&timer->task_work, snd_timer_work);
        timer->max_instances = 1000; /* default limit per 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;
}
EXPORT_SYMBOL(snd_timer_new);

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;
                pr_warn("ALSA: 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;
        struct snd_timer_instance *ti;

        mutex_lock(&register_mutex);
        list_del_init(&timer->device_list);
        /* wake up pending sleepers */
        list_for_each_entry(ti, &timer->open_list_head, open_list) {
                if (ti->disconnect)
                        ti->disconnect(ti);
        }
        mutex_unlock(&register_mutex);
        return 0;
}

void snd_timer_notify(struct snd_timer *timer, int event, struct timespec64 *tstamp)
{
        unsigned long flags;
        unsigned long resolution = 0;
        struct snd_timer_instance *ti, *ts;

        if (timer->card && timer->card->shutdown)
                return;
        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)
                resolution = snd_timer_hw_resolution(timer);
        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);
}
EXPORT_SYMBOL(snd_timer_notify);

/*
 * 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);
}
EXPORT_SYMBOL(snd_timer_global_new);

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

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);
}
EXPORT_SYMBOL(snd_timer_global_register);

/*
 *  System timer
 */

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

static void snd_timer_s_function(struct timer_list *t)
{
        struct snd_timer_system_private *priv = from_timer(priv, t,
                                                                tlist);
        struct snd_timer *timer = priv->snd_timer;
        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 = njiff;
        mod_timer(&priv->tlist, njiff);
        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 int snd_timer_s_close(struct snd_timer *timer)
{
        struct snd_timer_system_private *priv;

        priv = (struct snd_timer_system_private *)timer->private_data;
        del_timer_sync(&priv->tlist);
        return 0;
}

static const struct snd_timer_hardware snd_timer_system =
{
        .flags =        SNDRV_TIMER_HW_FIRST | SNDRV_TIMER_HW_WORK,
        .resolution =   1000000000L / HZ,
        .ticks =        10000000L,
        .close =        snd_timer_s_close,
        .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;
        }
        priv->snd_timer = timer;
        timer_setup(&priv->tlist, snd_timer_s_function, 0);
        timer->private_data = priv;
        timer->private_free = snd_timer_free_system;
        return snd_timer_global_register(timer);
}

#ifdef CONFIG_SND_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) {
                if (timer->card && timer->card->shutdown)
                        continue;
                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_SND_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_tread64 *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 timespec64 *tstamp,
                                     unsigned long resolution)
{
        struct snd_timer_user *tu = timeri->callback_data;
        struct snd_timer_tread64 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;
        memset(&r1, 0, sizeof(r1));
        r1.event = event;
        r1.tstamp_sec = tstamp->tv_sec;
        r1.tstamp_nsec = tstamp->tv_nsec;
        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_disconnect(struct snd_timer_instance *timeri)
{
        struct snd_timer_user *tu = timeri->callback_data;

        tu->disconnected = true;
        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_tread64 *r, r1;
        struct timespec64 tstamp;
        int prev, append = 0;

        memset(&r1, 0, sizeof(r1));
        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)
                        ktime_get_ts64(&tstamp);
                else
                        ktime_get_real_ts64(&tstamp);
        }
        if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) &&
            tu->last_resolution != resolution) {
                r1.event = SNDRV_TIMER_EVENT_RESOLUTION;
                r1.tstamp_sec = tstamp.tv_sec;
                r1.tstamp_nsec = tstamp.tv_nsec;
                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_sec = tstamp.tv_sec;
                        r->tstamp_nsec = tstamp.tv_nsec;
                        r->val += ticks;
                        append++;
                        goto __wake;
                }
        }
        r1.event = SNDRV_TIMER_EVENT_TICK;
        r1.tstamp_sec = tstamp.tv_sec;
        r1.tstamp_nsec = tstamp.tv_nsec;
        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 realloc_user_queue(struct snd_timer_user *tu, int size)
{
        struct snd_timer_read *queue = NULL;
        struct snd_timer_tread64 *tqueue = NULL;

        if (tu->tread) {
                tqueue = kcalloc(size, sizeof(*tqueue), GFP_KERNEL);
                if (!tqueue)
                        return -ENOMEM;
        } else {
                queue = kcalloc(size, sizeof(*queue), GFP_KERNEL);
                if (!queue)
                        return -ENOMEM;
        }

        spin_lock_irq(&tu->qlock);
        kfree(tu->queue);
        kfree(tu->tqueue);
        tu->queue_size = size;
        tu->queue = queue;
        tu->tqueue = tqueue;
        tu->qhead = tu->qtail = tu->qused = 0;
        spin_unlock_irq(&tu->qlock);

        return 0;
}

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

        err = stream_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->ioctl_lock);
        tu->ticks = 1;
        if (realloc_user_queue(tu, 128) < 0) {
                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;
                mutex_lock(&tu->ioctl_lock);
                if (tu->timeri) {
                        snd_timer_close(tu->timeri);
                        snd_timer_instance_free(tu->timeri);
                }
                mutex_unlock(&tu->ioctl_lock);
                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.device < 0) {
                                        id.device = 0;
                                } else {
                                        if (id.subdevice < 0)
                                                id.subdevice = 0;
                                        else if (id.subdevice < INT_MAX)
                                                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;
                strscpy(ginfo->id, t->id, sizeof(ginfo->id));
                strscpy(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 timer_set_gparams(struct snd_timer_gparams *gparams)
{
        struct snd_timer *t;
        int err;

        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_gparams(struct file *file,
                                  struct snd_timer_gparams __user *_gparams)
{
        struct snd_timer_gparams gparams;

        if (copy_from_user(&gparams, _gparams, sizeof(gparams)))
                return -EFAULT;
        return timer_set_gparams(&gparams);
}

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) {
                spin_lock_irq(&t->lock);
                gstatus.resolution = snd_timer_hw_resolution(t);
                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;
                }
                spin_unlock_irq(&t->lock);
        } 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;
        if (tu->timeri) {
                snd_timer_close(tu->timeri);
                snd_timer_instance_free(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;
        tu->timeri = snd_timer_instance_new(str);
        if (!tu->timeri) {
                err = -ENOMEM;
                goto __err;
        }

        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;
        tu->timeri->disconnect = snd_timer_user_disconnect;

        err = snd_timer_open(tu->timeri, &tselect.id, current->pid);
        if (err < 0) {
                snd_timer_instance_free(tu->timeri);
                tu->timeri = NULL;
        }

      __err:
        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;
        strscpy(info->id, t->id, sizeof(info->id));
        strscpy(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;
        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)) {
                u64 resolution;

                if (params.ticks < 1) {
                        err = -EINVAL;
                        goto _end;
                }

                /* Don't allow resolution less than 1ms */
                resolution = snd_timer_resolution(tu->timeri);
                resolution *= params.ticks;
                if (resolution < 1000000) {
                        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) {
                err = realloc_user_queue(tu, params.queue_size);
                if (err < 0)
                        goto _end;
        }
        spin_lock_irq(&tu->qlock);
        tu->qhead = tu->qtail = tu->qused = 0;
        if (tu->timeri->flags & SNDRV_TIMER_IFLG_EARLY_EVENT) {
                if (tu->tread) {
                        struct snd_timer_tread64 tread;
                        memset(&tread, 0, sizeof(tread));
                        tread.event = SNDRV_TIMER_EVENT_EARLY;
                        tread.tstamp_sec = 0;
                        tread.tstamp_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;
        spin_unlock_irq(&tu->qlock);
        err = 0;
 _end:
        if (copy_to_user(_params, &params, sizeof(params)))
                return -EFAULT;
        return err;
}

static int snd_timer_user_status32(struct file *file,
                                   struct snd_timer_status32 __user *_status)
 {
        struct snd_timer_user *tu;
        struct snd_timer_status32 status;

        tu = file->private_data;
        if (!tu->timeri)
                return -EBADFD;
        memset(&status, 0, sizeof(status));
        status.tstamp_sec = tu->tstamp.tv_sec;
        status.tstamp_nsec = tu->tstamp.tv_nsec;
        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_status64(struct file *file,
                                   struct snd_timer_status64 __user *_status)
{
        struct snd_timer_user *tu;
        struct snd_timer_status64 status;

        tu = file->private_data;
        if (!tu->timeri)
                return -EBADFD;
        memset(&status, 0, sizeof(status));
        status.tstamp_sec = tu->tstamp.tv_sec;
        status.tstamp_nsec = tu->tstamp.tv_nsec;
        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;
        err = snd_timer_start(tu->timeri, tu->ticks);
        if (err < 0)
                return err;
        return 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;
        err = snd_timer_stop(tu->timeri);
        if (err < 0)
                return err;

        return 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;
        /* start timer instead of continue if it's not used before */
        if (!(tu->timeri->flags & SNDRV_TIMER_IFLG_PAUSED))
                return snd_timer_user_start(file);
        tu->timeri->lost = 0;
        err = snd_timer_continue(tu->timeri);
        if (err < 0)
                return err;
        return 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;
        err = snd_timer_pause(tu->timeri);
        if (err < 0)
                return err;
        return 0;
}

static int snd_timer_user_tread(void __user *argp, struct snd_timer_user *tu,
                                unsigned int cmd, bool compat)
{
        int __user *p = argp;
        int xarg, old_tread;

        if (tu->timeri) /* too late */
                return -EBUSY;
        if (get_user(xarg, p))
                return -EFAULT;

        old_tread = tu->tread;

        if (!xarg)
                tu->tread = TREAD_FORMAT_NONE;
        else if (cmd == SNDRV_TIMER_IOCTL_TREAD64 ||
                 (IS_ENABLED(CONFIG_64BIT) && !compat))
                tu->tread = TREAD_FORMAT_TIME64;
        else
                tu->tread = TREAD_FORMAT_TIME32;

        if (tu->tread != old_tread &&
            realloc_user_queue(tu, tu->queue_size) < 0) {
                tu->tread = old_tread;
                return -ENOMEM;
        }

        return 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, bool compat)
{
        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_OLD:
        case SNDRV_TIMER_IOCTL_TREAD64:
                return snd_timer_user_tread(argp, tu, cmd, compat);
        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_STATUS32:
                return snd_timer_user_status32(file, argp);
        case SNDRV_TIMER_IOCTL_STATUS64:
                return snd_timer_user_status64(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 long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
                                 unsigned long arg)
{
        struct snd_timer_user *tu = file->private_data;
        long ret;

        mutex_lock(&tu->ioctl_lock);
        ret = __snd_timer_user_ioctl(file, cmd, arg, false);
        mutex_unlock(&tu->ioctl_lock);
        return ret;
}

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_tread64 *tread;
        struct snd_timer_tread32 tread32;
        struct snd_timer_user *tu;
        long result = 0, unit;
        int qhead;
        int err = 0;

        tu = file->private_data;
        switch (tu->tread) {
        case TREAD_FORMAT_TIME64:
                unit = sizeof(struct snd_timer_tread64);
                break;
        case TREAD_FORMAT_TIME32:
                unit = sizeof(struct snd_timer_tread32);
                break;
        case TREAD_FORMAT_NONE:
                unit = sizeof(struct snd_timer_read);
                break;
        default:
                WARN_ONCE(1, "Corrupt snd_timer_user\n");
                return -ENOTSUPP;
        }

        mutex_lock(&tu->ioctl_lock);
        spin_lock_irq(&tu->qlock);
        while ((long)count - result >= unit) {
                while (!tu->qused) {
                        wait_queue_entry_t wait;

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

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

                        spin_unlock_irq(&tu->qlock);
                        mutex_unlock(&tu->ioctl_lock);
                        schedule();
                        mutex_lock(&tu->ioctl_lock);
                        spin_lock_irq(&tu->qlock);

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

                        if (tu->disconnected) {
                                err = -ENODEV;
                                goto _error;
                        }
                        if (signal_pending(current)) {
                                err = -ERESTARTSYS;
                                goto _error;
                        }
                }

                qhead = tu->qhead++;
                tu->qhead %= tu->queue_size;
                tu->qused--;
                spin_unlock_irq(&tu->qlock);

                tread = &tu->tqueue[qhead];

                switch (tu->tread) {
                case TREAD_FORMAT_TIME64:
                        if (copy_to_user(buffer, tread,
                                         sizeof(struct snd_timer_tread64)))
                                err = -EFAULT;
                        break;
                case TREAD_FORMAT_TIME32:
                        memset(&tread32, 0, sizeof(tread32));
                        tread32 = (struct snd_timer_tread32) {
                                .event = tread->event,
                                .tstamp_sec = tread->tstamp_sec,
                                .tstamp_nsec = tread->tstamp_nsec,
                                .val = tread->val,
                        };

                        if (copy_to_user(buffer, &tread32, sizeof(tread32)))
                                err = -EFAULT;
                        break;
                case TREAD_FORMAT_NONE:
                        if (copy_to_user(buffer, &tu->queue[qhead],
                                         sizeof(struct snd_timer_read)))
                                err = -EFAULT;
                        break;
                default:
                        err = -ENOTSUPP;
                        break;
                }

                spin_lock_irq(&tu->qlock);
                if (err < 0)
                        goto _error;
                result += unit;
                buffer += unit;
        }
 _error:
        spin_unlock_irq(&tu->qlock);
        mutex_unlock(&tu->ioctl_lock);
        return result > 0 ? result : err;
}

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

        tu = file->private_data;

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

        mask = 0;
        spin_lock_irq(&tu->qlock);
        if (tu->qused)
                mask |= EPOLLIN | EPOLLRDNORM;
        if (tu->disconnected)
                mask |= EPOLLERR;
        spin_unlock_irq(&tu->qlock);

        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,
};

/* unregister the system timer */
static void snd_timer_free_all(void)
{
        struct snd_timer *timer, *n;

        list_for_each_entry_safe(timer, n, &snd_timer_list, device_list)
                snd_timer_free(timer);
}

static struct device timer_dev;

/*
 *  ENTRY functions
 */

static int __init alsa_timer_init(void)
{
        int err;

        snd_device_initialize(&timer_dev, NULL);
        dev_set_name(&timer_dev, "timer");

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

        err = snd_timer_register_system();
        if (err < 0) {
                pr_err("ALSA: unable to register system timer (%i)\n", err);
                goto put_timer;
        }

        err = snd_register_device(SNDRV_DEVICE_TYPE_TIMER, NULL, 0,
                                  &snd_timer_f_ops, NULL, &timer_dev);
        if (err < 0) {
                pr_err("ALSA: unable to register timer device (%i)\n", err);
                snd_timer_free_all();
                goto put_timer;
        }

        snd_timer_proc_init();
        return 0;

put_timer:
        put_device(&timer_dev);
        return err;
}

static void __exit alsa_timer_exit(void)
{
        snd_unregister_device(&timer_dev);
        snd_timer_free_all();
        put_device(&timer_dev);
        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)