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kernel/power/base/power/wakeup.c
/**
* struct wakeup_source - Representation of wakeup sources
*
* @total_time: Total time this wakeup source has been active.
* @max_time: Maximum time this wakeup source has been continuously active.
* @last_time: Monotonic clock when the wakeup source's was touched last time.
* @prevent_sleep_time: Total time this source has been preventing autosleep.
* @event_count: Number of signaled wakeup events.
* @active_count: Number of times the wakeup sorce was activated.
* @relax_count: Number of times the wakeup sorce was deactivated.
* @expire_count: Number of times the wakeup source's timeout has expired.
* @wakeup_count: Number of times the wakeup source might abort suspend.
* @active: Status of the wakeup source.
* @has_timeout: The wakeup source has been activated with a timeout.
*/
struct wakeup_source {
const char *name;
struct list_head entry;
spinlock_t lock;
struct timer_list timer;
unsigned long timer_expires;
ktime_t total_time;
ktime_t max_time;
ktime_t last_time;
ktime_t start_prevent_time;
ktime_t prevent_sleep_time;
unsigned long event_count;
unsigned long active_count;
unsigned long relax_count;
unsigned long expire_count;
unsigned long wakeup_count;
bool active:1;
bool autosleep_enabled:1;
};//初始化
static inline void wake_lock_init(struct wake_lock *lock, int type,const char *name)
{
wakeup_source_init(&lock->ws, name);
}
static inline void wakeup_source_init(struct wakeup_source *ws,
const char *name)
{
wakeup_source_prepare(ws, name);
wakeup_source_add(ws);
}
void wakeup_source_add(struct wakeup_source *ws)
{
unsigned long flags;
if (WARN_ON(!ws))
return;
spin_lock_init(&ws->lock);
setup_timer(&ws->timer, pm_wakeup_timer_fn, (unsigned long)ws);
ws->active = false;
ws->last_time = ktime_get();
spin_lock_irqsave(&events_lock, flags);
list_add_rcu(&ws->entry, &wakeup_sources);
spin_unlock_irqrestore(&events_lock, flags);
}
static void pm_wakeup_timer_fn(unsigned long data)
{
struct wakeup_source *ws = (struct wakeup_source *)data;
unsigned long flags;
spin_lock_irqsave(&ws->lock, flags);
if (ws->active && ws->timer_expires
&& time_after_eq(jiffies, ws->timer_expires)) {
wakeup_source_deactivate(ws);
ws->expire_count++;
}
spin_unlock_irqrestore(&ws->lock, flags);
}上锁
static inline void wake_lock(struct wake_lock *lock)
{
__pm_stay_awake(&lock->ws);
}
void __pm_stay_awake(struct wakeup_source *ws)
{
wakeup_source_report_event(ws);
}
static void wakeup_source_report_event(struct wakeup_source *ws)
{
ws->event_count++;
if (events_check_enabled)
ws->wakeup_count++;
if (!ws->active)
wakeup_source_activate(ws);
}
static void wakeup_source_activate(struct wakeup_source *ws)
{
unsigned int cec;
/*
* active wakeup source should bring the system
* out of PM_SUSPEND_FREEZE state
*/
freeze_wake();
ws->active = true;
ws->active_count++;
ws->last_time = ktime_get();
if (ws->autosleep_enabled)
ws->start_prevent_time = ws->last_time;
/* Increment the counter of events in progress. */
cec = atomic_inc_return(&combined_event_count);
trace_wakeup_source_activate(ws->name, cec);
} 解锁
static inline void wake_unlock(struct wake_lock *lock)
{
__pm_relax(&lock->ws);
}
void __pm_relax(struct wakeup_source *ws)
{
unsigned long flags;
if (!ws)
return;
spin_lock_irqsave(&ws->lock, flags);
if (ws->active)
wakeup_source_deactivate(ws);
spin_unlock_irqrestore(&ws->lock, flags);
}
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
unsigned int cnt, inpr, cec;
ktime_t duration;
ktime_t now;
ws->relax_count++;
/*
* __pm_relax() may be called directly or from a timer function.
* If it is called directly right after the timer function has been
* started, but before the timer function calls __pm_relax(), it is
* possible that __pm_stay_awake() will be called in the meantime and
* will set ws->active. Then, ws->active may be cleared immediately
* by the __pm_relax() called from the timer function, but in such a
* case ws->relax_count will be different from ws->active_count.
*/
if (ws->relax_count != ws->active_count) {
ws->relax_count--;
return;
}
ws->active = false;
now = ktime_get();
duration = ktime_sub(now, ws->last_time);
ws->total_time = ktime_add(ws->total_time, duration);
if (ktime_to_ns(duration) > ktime_to_ns(ws->max_time))
ws->max_time = duration;
ws->last_time = now;
del_timer(&ws->timer);
ws->timer_expires = 0;
if (ws->autosleep_enabled)
update_prevent_sleep_time(ws, now);
/*
* Increment the counter of registered wakeup events and decrement the
* couter of wakeup events in progress simultaneously.
*/
cec = atomic_add_return(MAX_IN_PROGRESS, &combined_event_count);
trace_wakeup_source_deactivate(ws->name, cec);
split_counters(&cnt, &inpr);
if (!inpr && waitqueue_active(&wakeup_count_wait_queue))
wake_up(&wakeup_count_wait_queue);
}超时锁
static inline void wake_lock_timeout(struct wake_lock *lock, long timeout)
{
__pm_wakeup_event(&lock->ws, jiffies_to_msecs(timeout));
}
void __pm_wakeup_event(struct wakeup_source *ws, unsigned int msec)
{
unsigned long flags;
unsigned long expires;
if (!ws)
return;
spin_lock_irqsave(&ws->lock, flags);
wakeup_source_report_event(ws);
if (!msec) {
wakeup_source_deactivate(ws);
goto unlock;
}
expires = jiffies + msecs_to_jiffies(msec);
if (!expires)
expires = 1;
if (!ws->timer_expires || time_after(expires, ws->timer_expires)) {
mod_timer(&ws->timer, expires);
ws->timer_expires = expires;
}
unlock:
spin_unlock_irqrestore(&ws->lock, flags);
}读/d/wakeup_sources查看唤醒锁的状态
/**
* print_wakeup_source_stats - Print wakeup source statistics information.
* @m: seq_file to print the statistics into.
* @ws: Wakeup source object to print the statistics for.
*/
static int print_wakeup_source_stats(struct seq_file *m,
struct wakeup_source *ws)
{
unsigned long flags;
ktime_t total_time;
ktime_t max_time;
unsigned long active_count;
ktime_t active_time;
ktime_t prevent_sleep_time;
int ret;
spin_lock_irqsave(&ws->lock, flags);
total_time = ws->total_time;
max_time = ws->max_time;
prevent_sleep_time = ws->prevent_sleep_time;
active_count = ws->active_count;
if (ws->active) {
ktime_t now = ktime_get();
active_time = ktime_sub(now, ws->last_time);
total_time = ktime_add(total_time, active_time);
if (active_time.tv64 > max_time.tv64)
max_time = active_time;
if (ws->autosleep_enabled)
prevent_sleep_time = ktime_add(prevent_sleep_time,
ktime_sub(now, ws->start_prevent_time));
} else {
active_time = ktime_set(0, 0);
}
ret = seq_printf(m, "%-12s\t%lu\t\t%lu\t\t%lu\t\t%lu\t\t"
"%lld\t\t%lld\t\t%lld\t\t%lld\t\t%lld\n",
ws->name, active_count, ws->event_count,
ws->wakeup_count, ws->expire_count,
ktime_to_ms(active_time), ktime_to_ms(total_time),
ktime_to_ms(max_time), ktime_to_ms(ws->last_time),
ktime_to_ms(prevent_sleep_time));
spin_unlock_irqrestore(&ws->lock, flags);
return ret;
}
/**
* wakeup_sources_stats_show - Print wakeup sources statistics information.
* @m: seq_file to print the statistics into.
*/
static int wakeup_sources_stats_show(struct seq_file *m, void *unused)
{
struct wakeup_source *ws;
seq_puts(m, "name\t\tactive_count\tevent_count\twakeup_count\t"
"expire_count\tactive_since\ttotal_time\tmax_time\t"
"last_change\tprevent_suspend_time\n");
rcu_read_lock();
list_for_each_entry_rcu(ws, &wakeup_sources, entry)
print_wakeup_source_stats(m, ws);
rcu_read_unlock();
return 0;
}active_count(有效的上锁次数，虽调用wake_lock,但锁之前已经锁定)
event_count(上锁次数，即调用wake_lock次数)
wakeup_count(唤醒计数)
expire_count(超时次数)
active_since(如果现在锁锁住，最后一次上锁的持续时间，如果现在没上锁,为0)
total_time(上锁总时间)
max_time (单次上锁最大时间)
last_change(最后一次上锁或解锁的时间)
prevent_suspend_time(没用到)
Android通过判断有没有存在锁来进行休眠或唤醒，其原理是通过判断变量combined_event_count的值实现的。
static atomic_t combined_event_count = ATOMIC_INIT(0);
#define IN_PROGRESS_BITS (sizeof(int) * 4)
#define MAX_IN_PROGRESS ((1 << IN_PROGRESS_BITS) - 1)
static void split_counters(unsigned int *cnt, unsigned int *inpr)
{
unsigned int comb = atomic_read(&combined_event_count);
*cnt = (comb >> IN_PROGRESS_BITS);//高16位 //解锁次数
*inpr = comb & MAX_IN_PROGRESS;//低16 记录目前已锁住的锁的数量
}
//wake_lock上锁调用
static void wakeup_source_activate(struct wakeup_source *ws){
atomic_inc_return(&combined_event_count);//低16加1
}
//wake_unlock/wake_lock_timeout解锁调用
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
/*
* Increment the counter of registered wakeup events and decrement the
* couter of wakeup events in progress simultaneously.
*/
cec = atomic_add_return(MAX_IN_PROGRESS, &combined_event_count);//低16位减1,高16位加一
}