4 * This interface provides a timer which is similarto hrtimers,
5 * but triggers a RTC alarm if the box is suspend.
7 * This interface is influenced by the Android RTC Alarm timer
10 * Copyright (C) 2010 IBM Corperation
12 * Author: John Stultz <john.stultz@linaro.org>
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License version 2 as
16 * published by the Free Software Foundation.
18 #include <linux/time.h>
19 #include <linux/hrtimer.h>
20 #include <linux/timerqueue.h>
21 #include <linux/rtc.h>
22 #include <linux/alarmtimer.h>
23 #include <linux/mutex.h>
24 #include <linux/platform_device.h>
25 #include <linux/posix-timers.h>
26 #include <linux/workqueue.h>
27 #include <linux/freezer.h>
30 * struct alarm_base - Alarm timer bases
31 * @lock: Lock for syncrhonized access to the base
32 * @timerqueue: Timerqueue head managing the list of events
33 * @timer: hrtimer used to schedule events while running
34 * @gettime: Function to read the time correlating to the base
35 * @base_clockid: clockid for the base
37 static struct alarm_base {
39 struct timerqueue_head timerqueue;
41 ktime_t (*gettime)(void);
42 clockid_t base_clockid;
43 } alarm_bases[ALARM_NUMTYPE];
45 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
46 static ktime_t freezer_delta;
47 static DEFINE_SPINLOCK(freezer_delta_lock);
49 #ifdef CONFIG_RTC_CLASS
50 /* rtc timer and device for setting alarm wakeups at suspend */
51 static struct rtc_timer rtctimer;
52 static struct rtc_device *rtcdev;
53 static DEFINE_SPINLOCK(rtcdev_lock);
56 * alarmtimer_get_rtcdev - Return selected rtcdevice
58 * This function returns the rtc device to use for wakealarms.
59 * If one has not already been chosen, it checks to see if a
60 * functional rtc device is available.
62 static struct rtc_device *alarmtimer_get_rtcdev(void)
65 struct rtc_device *ret;
67 spin_lock_irqsave(&rtcdev_lock, flags);
69 spin_unlock_irqrestore(&rtcdev_lock, flags);
75 static int alarmtimer_rtc_add_device(struct device *dev,
76 struct class_interface *class_intf)
79 struct rtc_device *rtc = to_rtc_device(dev);
84 if (!rtc->ops->set_alarm)
86 if (!device_may_wakeup(rtc->dev.parent))
89 spin_lock_irqsave(&rtcdev_lock, flags);
92 /* hold a reference so it doesn't go away */
95 spin_unlock_irqrestore(&rtcdev_lock, flags);
99 static struct class_interface alarmtimer_rtc_interface = {
100 .add_dev = &alarmtimer_rtc_add_device,
103 static int alarmtimer_rtc_interface_setup(void)
105 alarmtimer_rtc_interface.class = rtc_class;
106 return class_interface_register(&alarmtimer_rtc_interface);
108 static void alarmtimer_rtc_interface_remove(void)
110 class_interface_unregister(&alarmtimer_rtc_interface);
113 static inline struct rtc_device *alarmtimer_get_rtcdev(void)
117 #define rtcdev (NULL)
118 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
119 static inline void alarmtimer_rtc_interface_remove(void) { }
123 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
124 * @base: pointer to the base where the timer is being run
125 * @alarm: pointer to alarm being enqueued.
127 * Adds alarm to a alarm_base timerqueue and if necessary sets
130 * Must hold base->lock when calling.
132 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
134 timerqueue_add(&base->timerqueue, &alarm->node);
135 alarm->state |= ALARMTIMER_STATE_ENQUEUED;
137 if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
138 hrtimer_try_to_cancel(&base->timer);
139 hrtimer_start(&base->timer, alarm->node.expires,
145 * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue
146 * @base: pointer to the base where the timer is running
147 * @alarm: pointer to alarm being removed
149 * Removes alarm to a alarm_base timerqueue and if necessary sets
150 * a new timer to run.
152 * Must hold base->lock when calling.
154 static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
156 struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
158 if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
161 timerqueue_del(&base->timerqueue, &alarm->node);
162 alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
164 if (next == &alarm->node) {
165 hrtimer_try_to_cancel(&base->timer);
166 next = timerqueue_getnext(&base->timerqueue);
169 hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
175 * alarmtimer_fired - Handles alarm hrtimer being fired.
176 * @timer: pointer to hrtimer being run
178 * When a alarm timer fires, this runs through the timerqueue to
179 * see which alarms expired, and runs those. If there are more alarm
180 * timers queued for the future, we set the hrtimer to fire when
181 * when the next future alarm timer expires.
183 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
185 struct alarm_base *base = container_of(timer, struct alarm_base, timer);
186 struct timerqueue_node *next;
189 int ret = HRTIMER_NORESTART;
190 int restart = ALARMTIMER_NORESTART;
192 spin_lock_irqsave(&base->lock, flags);
193 now = base->gettime();
194 while ((next = timerqueue_getnext(&base->timerqueue))) {
196 ktime_t expired = next->expires;
198 if (expired.tv64 > now.tv64)
201 alarm = container_of(next, struct alarm, node);
203 timerqueue_del(&base->timerqueue, &alarm->node);
204 alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
206 alarm->state |= ALARMTIMER_STATE_CALLBACK;
207 spin_unlock_irqrestore(&base->lock, flags);
209 restart = alarm->function(alarm, now);
210 spin_lock_irqsave(&base->lock, flags);
211 alarm->state &= ~ALARMTIMER_STATE_CALLBACK;
213 if (restart != ALARMTIMER_NORESTART) {
214 timerqueue_add(&base->timerqueue, &alarm->node);
215 alarm->state |= ALARMTIMER_STATE_ENQUEUED;
220 hrtimer_set_expires(&base->timer, next->expires);
221 ret = HRTIMER_RESTART;
223 spin_unlock_irqrestore(&base->lock, flags);
229 ktime_t alarm_expires_remaining(const struct alarm *alarm)
231 struct alarm_base *base = &alarm_bases[alarm->type];
232 return ktime_sub(alarm->node.expires, base->gettime());
235 #ifdef CONFIG_RTC_CLASS
237 * alarmtimer_suspend - Suspend time callback
241 * When we are going into suspend, we look through the bases
242 * to see which is the soonest timer to expire. We then
243 * set an rtc timer to fire that far into the future, which
244 * will wake us from suspend.
246 static int alarmtimer_suspend(struct device *dev)
251 struct rtc_device *rtc;
254 spin_lock_irqsave(&freezer_delta_lock, flags);
256 freezer_delta = ktime_set(0, 0);
257 spin_unlock_irqrestore(&freezer_delta_lock, flags);
259 rtc = alarmtimer_get_rtcdev();
260 /* If we have no rtcdev, just return */
264 /* Find the soonest timer to expire*/
265 for (i = 0; i < ALARM_NUMTYPE; i++) {
266 struct alarm_base *base = &alarm_bases[i];
267 struct timerqueue_node *next;
270 spin_lock_irqsave(&base->lock, flags);
271 next = timerqueue_getnext(&base->timerqueue);
272 spin_unlock_irqrestore(&base->lock, flags);
275 delta = ktime_sub(next->expires, base->gettime());
276 if (!min.tv64 || (delta.tv64 < min.tv64))
282 /* XXX - Should we enforce a minimum sleep time? */
283 WARN_ON(min.tv64 < NSEC_PER_SEC);
285 /* Setup an rtc timer to fire that far in the future */
286 rtc_timer_cancel(rtc, &rtctimer);
287 rtc_read_time(rtc, &tm);
288 now = rtc_tm_to_ktime(tm);
289 now = ktime_add(now, min);
291 rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
296 static int alarmtimer_suspend(struct device *dev)
302 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
306 struct alarm_base *base = &alarm_bases[type];
308 delta = ktime_sub(absexp, base->gettime());
310 spin_lock_irqsave(&freezer_delta_lock, flags);
311 if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
312 freezer_delta = delta;
313 spin_unlock_irqrestore(&freezer_delta_lock, flags);
318 * alarm_init - Initialize an alarm structure
319 * @alarm: ptr to alarm to be initialized
320 * @type: the type of the alarm
321 * @function: callback that is run when the alarm fires
323 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
324 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
326 timerqueue_init(&alarm->node);
327 alarm->function = function;
329 alarm->state = ALARMTIMER_STATE_INACTIVE;
333 * alarm_start - Sets an alarm to fire
334 * @alarm: ptr to alarm to set
335 * @start: time to run the alarm
337 void alarm_start(struct alarm *alarm, ktime_t start)
339 struct alarm_base *base = &alarm_bases[alarm->type];
342 spin_lock_irqsave(&base->lock, flags);
343 if (alarmtimer_active(alarm))
344 alarmtimer_remove(base, alarm);
345 alarm->node.expires = start;
346 alarmtimer_enqueue(base, alarm);
347 spin_unlock_irqrestore(&base->lock, flags);
351 * alarm_try_to_cancel - Tries to cancel an alarm timer
352 * @alarm: ptr to alarm to be canceled
354 * Returns 1 if the timer was canceled, 0 if it was not running,
355 * and -1 if the callback was running
357 int alarm_try_to_cancel(struct alarm *alarm)
359 struct alarm_base *base = &alarm_bases[alarm->type];
362 spin_lock_irqsave(&base->lock, flags);
364 if (alarmtimer_callback_running(alarm))
367 if (alarmtimer_is_queued(alarm)) {
368 alarmtimer_remove(base, alarm);
373 spin_unlock_irqrestore(&base->lock, flags);
379 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
380 * @alarm: ptr to alarm to be canceled
382 * Returns 1 if the timer was canceled, 0 if it was not active.
384 int alarm_cancel(struct alarm *alarm)
387 int ret = alarm_try_to_cancel(alarm);
395 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
400 delta = ktime_sub(now, alarm->node.expires);
405 if (unlikely(delta.tv64 >= interval.tv64)) {
406 s64 incr = ktime_to_ns(interval);
408 overrun = ktime_divns(delta, incr);
410 alarm->node.expires = ktime_add_ns(alarm->node.expires,
413 if (alarm->node.expires.tv64 > now.tv64)
416 * This (and the ktime_add() below) is the
417 * correction for exact:
422 alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
430 * clock2alarm - helper that converts from clockid to alarmtypes
433 static enum alarmtimer_type clock2alarm(clockid_t clockid)
435 if (clockid == CLOCK_REALTIME_ALARM)
436 return ALARM_REALTIME;
437 if (clockid == CLOCK_BOOTTIME_ALARM)
438 return ALARM_BOOTTIME;
443 * alarm_handle_timer - Callback for posix timers
444 * @alarm: alarm that fired
446 * Posix timer callback for expired alarm timers.
448 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
452 struct k_itimer *ptr = container_of(alarm, struct k_itimer,
453 it.alarm.alarmtimer);
454 enum alarmtimer_restart result = ALARMTIMER_NORESTART;
456 spin_lock_irqsave(&ptr->it_lock, flags);
457 if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
458 if (posix_timer_event(ptr, 0) != 0)
462 /* Re-add periodic timers */
463 if (ptr->it.alarm.interval.tv64) {
464 ptr->it_overrun += alarm_forward(alarm, now,
465 ptr->it.alarm.interval);
466 result = ALARMTIMER_RESTART;
468 spin_unlock_irqrestore(&ptr->it_lock, flags);
474 * alarm_clock_getres - posix getres interface
475 * @which_clock: clockid
476 * @tp: timespec to fill
478 * Returns the granularity of underlying alarm base clock
480 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
482 clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
484 if (!alarmtimer_get_rtcdev())
487 return hrtimer_get_res(baseid, tp);
491 * alarm_clock_get - posix clock_get interface
492 * @which_clock: clockid
493 * @tp: timespec to fill.
495 * Provides the underlying alarm base time.
497 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
499 struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
501 if (!alarmtimer_get_rtcdev())
504 *tp = ktime_to_timespec(base->gettime());
509 * alarm_timer_create - posix timer_create interface
510 * @new_timer: k_itimer pointer to manage
512 * Initializes the k_itimer structure.
514 static int alarm_timer_create(struct k_itimer *new_timer)
516 enum alarmtimer_type type;
517 struct alarm_base *base;
519 if (!alarmtimer_get_rtcdev())
522 if (!capable(CAP_WAKE_ALARM))
525 type = clock2alarm(new_timer->it_clock);
526 base = &alarm_bases[type];
527 alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
532 * alarm_timer_get - posix timer_get interface
533 * @new_timer: k_itimer pointer
534 * @cur_setting: itimerspec data to fill
536 * Copies out the current itimerspec data
538 static void alarm_timer_get(struct k_itimer *timr,
539 struct itimerspec *cur_setting)
541 ktime_t relative_expiry_time =
542 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
544 if (ktime_to_ns(relative_expiry_time) > 0) {
545 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
547 cur_setting->it_value.tv_sec = 0;
548 cur_setting->it_value.tv_nsec = 0;
551 cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
555 * alarm_timer_del - posix timer_del interface
556 * @timr: k_itimer pointer to be deleted
558 * Cancels any programmed alarms for the given timer.
560 static int alarm_timer_del(struct k_itimer *timr)
565 if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
572 * alarm_timer_set - posix timer_set interface
573 * @timr: k_itimer pointer to be deleted
574 * @flags: timer flags
575 * @new_setting: itimerspec to be used
576 * @old_setting: itimerspec being replaced
578 * Sets the timer to new_setting, and starts the timer.
580 static int alarm_timer_set(struct k_itimer *timr, int flags,
581 struct itimerspec *new_setting,
582 struct itimerspec *old_setting)
589 if (flags & ~TIMER_ABSTIME)
593 alarm_timer_get(timr, old_setting);
595 /* If the timer was already set, cancel it */
596 if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
599 /* start the timer */
600 timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
601 exp = timespec_to_ktime(new_setting->it_value);
602 /* Convert (if necessary) to absolute time */
603 if (flags != TIMER_ABSTIME) {
606 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
607 exp = ktime_add_safe(now, exp);
610 alarm_start(&timr->it.alarm.alarmtimer, exp);
615 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
616 * @alarm: ptr to alarm that fired
618 * Wakes up the task that set the alarmtimer
620 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
623 struct task_struct *task = (struct task_struct *)alarm->data;
627 wake_up_process(task);
628 return ALARMTIMER_NORESTART;
632 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
633 * @alarm: ptr to alarmtimer
634 * @absexp: absolute expiration time
636 * Sets the alarm timer and sleeps until it is fired or interrupted.
638 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
640 alarm->data = (void *)current;
642 set_current_state(TASK_INTERRUPTIBLE);
643 alarm_start(alarm, absexp);
644 if (likely(alarm->data))
648 } while (alarm->data && !signal_pending(current));
650 __set_current_state(TASK_RUNNING);
652 return (alarm->data == NULL);
657 * update_rmtp - Update remaining timespec value
658 * @exp: expiration time
660 * @rmtp: user pointer to remaining timepsec value
662 * Helper function that fills in rmtp value with time between
663 * now and the exp value
665 static int update_rmtp(ktime_t exp, enum alarmtimer_type type,
666 struct timespec __user *rmtp)
671 rem = ktime_sub(exp, alarm_bases[type].gettime());
675 rmt = ktime_to_timespec(rem);
677 if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
685 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
686 * @restart: ptr to restart block
688 * Handles restarted clock_nanosleep calls
690 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
692 enum alarmtimer_type type = restart->nanosleep.clockid;
694 struct timespec __user *rmtp;
698 exp.tv64 = restart->nanosleep.expires;
699 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
701 if (alarmtimer_do_nsleep(&alarm, exp))
704 if (freezing(current))
705 alarmtimer_freezerset(exp, type);
707 rmtp = restart->nanosleep.rmtp;
709 ret = update_rmtp(exp, type, rmtp);
715 /* The other values in restart are already filled in */
716 ret = -ERESTART_RESTARTBLOCK;
722 * alarm_timer_nsleep - alarmtimer nanosleep
723 * @which_clock: clockid
724 * @flags: determins abstime or relative
725 * @tsreq: requested sleep time (abs or rel)
726 * @rmtp: remaining sleep time saved
728 * Handles clock_nanosleep calls against _ALARM clockids
730 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
731 struct timespec *tsreq, struct timespec __user *rmtp)
733 enum alarmtimer_type type = clock2alarm(which_clock);
737 struct restart_block *restart;
739 if (!alarmtimer_get_rtcdev())
742 if (flags & ~TIMER_ABSTIME)
745 if (!capable(CAP_WAKE_ALARM))
748 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
750 exp = timespec_to_ktime(*tsreq);
751 /* Convert (if necessary) to absolute time */
752 if (flags != TIMER_ABSTIME) {
753 ktime_t now = alarm_bases[type].gettime();
754 exp = ktime_add(now, exp);
757 if (alarmtimer_do_nsleep(&alarm, exp))
760 if (freezing(current))
761 alarmtimer_freezerset(exp, type);
763 /* abs timers don't set remaining time or restart */
764 if (flags == TIMER_ABSTIME) {
765 ret = -ERESTARTNOHAND;
770 ret = update_rmtp(exp, type, rmtp);
775 restart = ¤t_thread_info()->restart_block;
776 restart->fn = alarm_timer_nsleep_restart;
777 restart->nanosleep.clockid = type;
778 restart->nanosleep.expires = exp.tv64;
779 restart->nanosleep.rmtp = rmtp;
780 ret = -ERESTART_RESTARTBLOCK;
787 /* Suspend hook structures */
788 static const struct dev_pm_ops alarmtimer_pm_ops = {
789 .suspend = alarmtimer_suspend,
792 static struct platform_driver alarmtimer_driver = {
794 .name = "alarmtimer",
795 .pm = &alarmtimer_pm_ops,
800 * alarmtimer_init - Initialize alarm timer code
802 * This function initializes the alarm bases and registers
803 * the posix clock ids.
805 static int __init alarmtimer_init(void)
807 struct platform_device *pdev;
810 struct k_clock alarm_clock = {
811 .clock_getres = alarm_clock_getres,
812 .clock_get = alarm_clock_get,
813 .timer_create = alarm_timer_create,
814 .timer_set = alarm_timer_set,
815 .timer_del = alarm_timer_del,
816 .timer_get = alarm_timer_get,
817 .nsleep = alarm_timer_nsleep,
820 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
821 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
823 /* Initialize alarm bases */
824 alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
825 alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
826 alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
827 alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
828 for (i = 0; i < ALARM_NUMTYPE; i++) {
829 timerqueue_init_head(&alarm_bases[i].timerqueue);
830 spin_lock_init(&alarm_bases[i].lock);
831 hrtimer_init(&alarm_bases[i].timer,
832 alarm_bases[i].base_clockid,
834 alarm_bases[i].timer.function = alarmtimer_fired;
837 error = alarmtimer_rtc_interface_setup();
841 error = platform_driver_register(&alarmtimer_driver);
845 pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
847 error = PTR_ERR(pdev);
853 platform_driver_unregister(&alarmtimer_driver);
855 alarmtimer_rtc_interface_remove();
858 device_initcall(alarmtimer_init);