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timer.c
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// 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(®ister_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(®ister_mutex);
snd_timer_request(tid);
mutex_lock(®ister_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(®ister_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(®ister_mutex);
snd_timer_close_locked(timeri, &card_dev_to_put);
mutex_unlock(®ister_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(®ister_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;
}