Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2348 insertions, 0 deletions

diff --git a/sound/core/timer.c b/sound/core/timer.c
new file mode 100644
index 000000000..e08a37c23
--- /dev/null
+++ b/sound/core/timer.c
@@ -0,0 +1,2348 @@
+// 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 snd_fasync *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);
+	snd_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);
+	snd_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;
+	snd_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);
+		snd_fasync_free(tu->fasync);
+		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 snd_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)