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alarmtimer: Add functions for timerfd support

Add functions needed for hooking up alarmtimer to timerfd:

* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
  the expires time has already been updated (as with alarm_forward).

* alarm_forward_now: Similar to hrtimer_forward_now, move the expires
  time forward to an interval from the current time of the associated clock.

* alarm_start_relative: Start an alarmtimer with an expires time relative to
  the current time of the associated clock.

* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
  amount of time remaining until alarm expiry.

Signed-off-by: Todd Poynor <>
Signed-off-by: John Stultz <>
Todd Poynor 9 years ago committed by John Stultz
  1. 4
  2. 39


@ -44,10 +44,14 @@ struct alarm {
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
enum alarmtimer_restart (*function)(struct alarm *, ktime_t));
int alarm_start(struct alarm *alarm, ktime_t start);
int alarm_start_relative(struct alarm *alarm, ktime_t start);
void alarm_restart(struct alarm *alarm);
int alarm_try_to_cancel(struct alarm *alarm);
int alarm_cancel(struct alarm *alarm);
u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);
u64 alarm_forward_now(struct alarm *alarm, ktime_t interval);
ktime_t alarm_expires_remaining(const struct alarm *alarm);
/* Provide way to access the rtc device being used by alarmtimers */
struct rtc_device *alarmtimer_get_rtcdev(void);


@ -199,6 +199,12 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
ktime_t alarm_expires_remaining(const struct alarm *alarm)
struct alarm_base *base = &alarm_bases[alarm->type];
return ktime_sub(alarm->node.expires, base->gettime());
* alarmtimer_suspend - Suspend time callback
@ -305,7 +311,7 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
* alarm_start - Sets an alarm to fire
* alarm_start - Sets an absolute alarm to fire
* @alarm: ptr to alarm to set
* @start: time to run the alarm
@ -324,6 +330,31 @@ int alarm_start(struct alarm *alarm, ktime_t start)
return ret;
* alarm_start_relative - Sets a relative alarm to fire
* @alarm: ptr to alarm to set
* @start: time relative to now to run the alarm
int alarm_start_relative(struct alarm *alarm, ktime_t start)
struct alarm_base *base = &alarm_bases[alarm->type];
start = ktime_add(start, base->gettime());
return alarm_start(alarm, start);
void alarm_restart(struct alarm *alarm)
struct alarm_base *base = &alarm_bases[alarm->type];
unsigned long flags;
spin_lock_irqsave(&base->lock, flags);
hrtimer_set_expires(&alarm->timer, alarm->node.expires);
alarmtimer_enqueue(base, alarm);
spin_unlock_irqrestore(&base->lock, flags);
* alarm_try_to_cancel - Tries to cancel an alarm timer
* @alarm: ptr to alarm to be canceled
@ -394,6 +425,12 @@ u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
return overrun;
u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
struct alarm_base *base = &alarm_bases[alarm->type];
return alarm_forward(alarm, base->gettime(), interval);