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;
40 ktime_t (*gettime)(void);
41 clockid_t base_clockid;
42 } alarm_bases[ALARM_NUMTYPE];
44 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
45 static ktime_t freezer_delta;
46 static DEFINE_SPINLOCK(freezer_delta_lock);
48 static struct wakeup_source *ws;
50 #ifdef CONFIG_RTC_CLASS
51 /* rtc timer and device for setting alarm wakeups at suspend */
52 static struct rtc_timer rtctimer;
53 static struct rtc_device *rtcdev;
54 static DEFINE_SPINLOCK(rtcdev_lock);
57 * alarmtimer_get_rtcdev - Return selected rtcdevice
59 * This function returns the rtc device to use for wakealarms.
60 * If one has not already been chosen, it checks to see if a
61 * functional rtc device is available.
63 struct rtc_device *alarmtimer_get_rtcdev(void)
66 struct rtc_device *ret;
68 spin_lock_irqsave(&rtcdev_lock, flags);
70 spin_unlock_irqrestore(&rtcdev_lock, flags);
76 static int alarmtimer_rtc_add_device(struct device *dev,
77 struct class_interface *class_intf)
80 struct rtc_device *rtc = to_rtc_device(dev);
85 if (!rtc->ops->set_alarm)
87 if (!device_may_wakeup(rtc->dev.parent))
90 spin_lock_irqsave(&rtcdev_lock, flags);
93 /* hold a reference so it doesn't go away */
96 spin_unlock_irqrestore(&rtcdev_lock, flags);
100 static inline void alarmtimer_rtc_timer_init(void)
102 rtc_timer_init(&rtctimer, NULL, NULL);
105 static struct class_interface alarmtimer_rtc_interface = {
106 .add_dev = &alarmtimer_rtc_add_device,
109 static int alarmtimer_rtc_interface_setup(void)
111 alarmtimer_rtc_interface.class = rtc_class;
112 return class_interface_register(&alarmtimer_rtc_interface);
114 static void alarmtimer_rtc_interface_remove(void)
116 class_interface_unregister(&alarmtimer_rtc_interface);
119 struct rtc_device *alarmtimer_get_rtcdev(void)
123 #define rtcdev (NULL)
124 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
125 static inline void alarmtimer_rtc_interface_remove(void) { }
126 static inline void alarmtimer_rtc_timer_init(void) { }
130 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
131 * @base: pointer to the base where the timer is being run
132 * @alarm: pointer to alarm being enqueued.
134 * Adds alarm to a alarm_base timerqueue
136 * Must hold base->lock when calling.
138 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
140 if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
141 timerqueue_del(&base->timerqueue, &alarm->node);
143 timerqueue_add(&base->timerqueue, &alarm->node);
144 alarm->state |= ALARMTIMER_STATE_ENQUEUED;
148 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
149 * @base: pointer to the base where the timer is running
150 * @alarm: pointer to alarm being removed
152 * Removes alarm to a alarm_base timerqueue
154 * Must hold base->lock when calling.
156 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
158 if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
161 timerqueue_del(&base->timerqueue, &alarm->node);
162 alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
167 * alarmtimer_fired - Handles alarm hrtimer being fired.
168 * @timer: pointer to hrtimer being run
170 * When a alarm timer fires, this runs through the timerqueue to
171 * see which alarms expired, and runs those. If there are more alarm
172 * timers queued for the future, we set the hrtimer to fire when
173 * when the next future alarm timer expires.
175 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
177 struct alarm *alarm = container_of(timer, struct alarm, timer);
178 struct alarm_base *base = &alarm_bases[alarm->type];
180 int ret = HRTIMER_NORESTART;
181 int restart = ALARMTIMER_NORESTART;
183 spin_lock_irqsave(&base->lock, flags);
184 alarmtimer_dequeue(base, alarm);
185 spin_unlock_irqrestore(&base->lock, flags);
188 restart = alarm->function(alarm, base->gettime());
190 spin_lock_irqsave(&base->lock, flags);
191 if (restart != ALARMTIMER_NORESTART) {
192 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
193 alarmtimer_enqueue(base, alarm);
194 ret = HRTIMER_RESTART;
196 spin_unlock_irqrestore(&base->lock, flags);
202 ktime_t alarm_expires_remaining(const struct alarm *alarm)
204 struct alarm_base *base = &alarm_bases[alarm->type];
205 return ktime_sub(alarm->node.expires, base->gettime());
208 #ifdef CONFIG_RTC_CLASS
210 * alarmtimer_suspend - Suspend time callback
214 * When we are going into suspend, we look through the bases
215 * to see which is the soonest timer to expire. We then
216 * set an rtc timer to fire that far into the future, which
217 * will wake us from suspend.
219 static int alarmtimer_suspend(struct device *dev)
224 struct rtc_device *rtc;
228 spin_lock_irqsave(&freezer_delta_lock, flags);
230 freezer_delta = ktime_set(0, 0);
231 spin_unlock_irqrestore(&freezer_delta_lock, flags);
233 rtc = alarmtimer_get_rtcdev();
234 /* If we have no rtcdev, just return */
238 /* Find the soonest timer to expire*/
239 for (i = 0; i < ALARM_NUMTYPE; i++) {
240 struct alarm_base *base = &alarm_bases[i];
241 struct timerqueue_node *next;
244 spin_lock_irqsave(&base->lock, flags);
245 next = timerqueue_getnext(&base->timerqueue);
246 spin_unlock_irqrestore(&base->lock, flags);
249 delta = ktime_sub(next->expires, base->gettime());
250 if (!min.tv64 || (delta.tv64 < min.tv64))
256 if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
257 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
261 /* Setup an rtc timer to fire that far in the future */
262 rtc_timer_cancel(rtc, &rtctimer);
263 rtc_read_time(rtc, &tm);
264 now = rtc_tm_to_ktime(tm);
265 now = ktime_add(now, min);
267 /* Set alarm, if in the past reject suspend briefly to handle */
268 ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
270 __pm_wakeup_event(ws, MSEC_PER_SEC);
274 static int alarmtimer_suspend(struct device *dev)
280 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
284 struct alarm_base *base = &alarm_bases[type];
286 delta = ktime_sub(absexp, base->gettime());
288 spin_lock_irqsave(&freezer_delta_lock, flags);
289 if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
290 freezer_delta = delta;
291 spin_unlock_irqrestore(&freezer_delta_lock, flags);
296 * alarm_init - Initialize an alarm structure
297 * @alarm: ptr to alarm to be initialized
298 * @type: the type of the alarm
299 * @function: callback that is run when the alarm fires
301 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
302 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
304 timerqueue_init(&alarm->node);
305 hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
307 alarm->timer.function = alarmtimer_fired;
308 alarm->function = function;
310 alarm->state = ALARMTIMER_STATE_INACTIVE;
314 * alarm_start - Sets an absolute alarm to fire
315 * @alarm: ptr to alarm to set
316 * @start: time to run the alarm
318 int alarm_start(struct alarm *alarm, ktime_t start)
320 struct alarm_base *base = &alarm_bases[alarm->type];
324 spin_lock_irqsave(&base->lock, flags);
325 alarm->node.expires = start;
326 alarmtimer_enqueue(base, alarm);
327 ret = hrtimer_start(&alarm->timer, alarm->node.expires,
329 spin_unlock_irqrestore(&base->lock, flags);
334 * alarm_start_relative - Sets a relative alarm to fire
335 * @alarm: ptr to alarm to set
336 * @start: time relative to now to run the alarm
338 int alarm_start_relative(struct alarm *alarm, ktime_t start)
340 struct alarm_base *base = &alarm_bases[alarm->type];
342 start = ktime_add(start, base->gettime());
343 return alarm_start(alarm, start);
346 void alarm_restart(struct alarm *alarm)
348 struct alarm_base *base = &alarm_bases[alarm->type];
351 spin_lock_irqsave(&base->lock, flags);
352 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
353 hrtimer_restart(&alarm->timer);
354 alarmtimer_enqueue(base, alarm);
355 spin_unlock_irqrestore(&base->lock, flags);
359 * alarm_try_to_cancel - Tries to cancel an alarm timer
360 * @alarm: ptr to alarm to be canceled
362 * Returns 1 if the timer was canceled, 0 if it was not running,
363 * and -1 if the callback was running
365 int alarm_try_to_cancel(struct alarm *alarm)
367 struct alarm_base *base = &alarm_bases[alarm->type];
371 spin_lock_irqsave(&base->lock, flags);
372 ret = hrtimer_try_to_cancel(&alarm->timer);
374 alarmtimer_dequeue(base, alarm);
375 spin_unlock_irqrestore(&base->lock, flags);
381 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
382 * @alarm: ptr to alarm to be canceled
384 * Returns 1 if the timer was canceled, 0 if it was not active.
386 int alarm_cancel(struct alarm *alarm)
389 int ret = alarm_try_to_cancel(alarm);
397 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
402 delta = ktime_sub(now, alarm->node.expires);
407 if (unlikely(delta.tv64 >= interval.tv64)) {
408 s64 incr = ktime_to_ns(interval);
410 overrun = ktime_divns(delta, incr);
412 alarm->node.expires = ktime_add_ns(alarm->node.expires,
415 if (alarm->node.expires.tv64 > now.tv64)
418 * This (and the ktime_add() below) is the
419 * correction for exact:
424 alarm->node.expires = ktime_add(alarm->node.expires, interval);
428 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
430 struct alarm_base *base = &alarm_bases[alarm->type];
432 return alarm_forward(alarm, base->gettime(), interval);
438 * clock2alarm - helper that converts from clockid to alarmtypes
441 static enum alarmtimer_type clock2alarm(clockid_t clockid)
443 if (clockid == CLOCK_REALTIME_ALARM)
444 return ALARM_REALTIME;
445 if (clockid == CLOCK_BOOTTIME_ALARM)
446 return ALARM_BOOTTIME;
451 * alarm_handle_timer - Callback for posix timers
452 * @alarm: alarm that fired
454 * Posix timer callback for expired alarm timers.
456 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
459 struct k_itimer *ptr = container_of(alarm, struct k_itimer,
460 it.alarm.alarmtimer);
461 if (posix_timer_event(ptr, 0) != 0)
464 /* Re-add periodic timers */
465 if (ptr->it.alarm.interval.tv64) {
466 ptr->it_overrun += alarm_forward(alarm, now,
467 ptr->it.alarm.interval);
468 return ALARMTIMER_RESTART;
470 return ALARMTIMER_NORESTART;
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 the itimerspec data out from the k_itimer
538 static void alarm_timer_get(struct k_itimer *timr,
539 struct itimerspec *cur_setting)
541 memset(cur_setting, 0, sizeof(struct itimerspec));
543 cur_setting->it_interval =
544 ktime_to_timespec(timr->it.alarm.interval);
545 cur_setting->it_value =
546 ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
551 * alarm_timer_del - posix timer_del interface
552 * @timr: k_itimer pointer to be deleted
554 * Cancels any programmed alarms for the given timer.
556 static int alarm_timer_del(struct k_itimer *timr)
561 if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
568 * alarm_timer_set - posix timer_set interface
569 * @timr: k_itimer pointer to be deleted
570 * @flags: timer flags
571 * @new_setting: itimerspec to be used
572 * @old_setting: itimerspec being replaced
574 * Sets the timer to new_setting, and starts the timer.
576 static int alarm_timer_set(struct k_itimer *timr, int flags,
577 struct itimerspec *new_setting,
578 struct itimerspec *old_setting)
584 alarm_timer_get(timr, old_setting);
586 /* If the timer was already set, cancel it */
587 if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
590 /* start the timer */
591 timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
592 alarm_start(&timr->it.alarm.alarmtimer,
593 timespec_to_ktime(new_setting->it_value));
598 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
599 * @alarm: ptr to alarm that fired
601 * Wakes up the task that set the alarmtimer
603 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
606 struct task_struct *task = (struct task_struct *)alarm->data;
610 wake_up_process(task);
611 return ALARMTIMER_NORESTART;
615 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
616 * @alarm: ptr to alarmtimer
617 * @absexp: absolute expiration time
619 * Sets the alarm timer and sleeps until it is fired or interrupted.
621 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
623 alarm->data = (void *)current;
625 set_current_state(TASK_INTERRUPTIBLE);
626 alarm_start(alarm, absexp);
627 if (likely(alarm->data))
631 } while (alarm->data && !signal_pending(current));
633 __set_current_state(TASK_RUNNING);
635 return (alarm->data == NULL);
640 * update_rmtp - Update remaining timespec value
641 * @exp: expiration time
643 * @rmtp: user pointer to remaining timepsec value
645 * Helper function that fills in rmtp value with time between
646 * now and the exp value
648 static int update_rmtp(ktime_t exp, enum alarmtimer_type type,
649 struct timespec __user *rmtp)
654 rem = ktime_sub(exp, alarm_bases[type].gettime());
658 rmt = ktime_to_timespec(rem);
660 if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
668 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
669 * @restart: ptr to restart block
671 * Handles restarted clock_nanosleep calls
673 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
675 enum alarmtimer_type type = restart->nanosleep.clockid;
677 struct timespec __user *rmtp;
681 exp.tv64 = restart->nanosleep.expires;
682 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
684 if (alarmtimer_do_nsleep(&alarm, exp))
687 if (freezing(current))
688 alarmtimer_freezerset(exp, type);
690 rmtp = restart->nanosleep.rmtp;
692 ret = update_rmtp(exp, type, rmtp);
698 /* The other values in restart are already filled in */
699 ret = -ERESTART_RESTARTBLOCK;
705 * alarm_timer_nsleep - alarmtimer nanosleep
706 * @which_clock: clockid
707 * @flags: determins abstime or relative
708 * @tsreq: requested sleep time (abs or rel)
709 * @rmtp: remaining sleep time saved
711 * Handles clock_nanosleep calls against _ALARM clockids
713 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
714 struct timespec *tsreq, struct timespec __user *rmtp)
716 enum alarmtimer_type type = clock2alarm(which_clock);
720 struct restart_block *restart;
722 if (!alarmtimer_get_rtcdev())
725 if (!capable(CAP_WAKE_ALARM))
728 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
730 exp = timespec_to_ktime(*tsreq);
731 /* Convert (if necessary) to absolute time */
732 if (flags != TIMER_ABSTIME) {
733 ktime_t now = alarm_bases[type].gettime();
734 exp = ktime_add(now, exp);
737 if (alarmtimer_do_nsleep(&alarm, exp))
740 if (freezing(current))
741 alarmtimer_freezerset(exp, type);
743 /* abs timers don't set remaining time or restart */
744 if (flags == TIMER_ABSTIME) {
745 ret = -ERESTARTNOHAND;
750 ret = update_rmtp(exp, type, rmtp);
755 restart = ¤t_thread_info()->restart_block;
756 restart->fn = alarm_timer_nsleep_restart;
757 restart->nanosleep.clockid = type;
758 restart->nanosleep.expires = exp.tv64;
759 restart->nanosleep.rmtp = rmtp;
760 ret = -ERESTART_RESTARTBLOCK;
767 /* Suspend hook structures */
768 static const struct dev_pm_ops alarmtimer_pm_ops = {
769 .suspend = alarmtimer_suspend,
772 static struct platform_driver alarmtimer_driver = {
774 .name = "alarmtimer",
775 .pm = &alarmtimer_pm_ops,
780 * alarmtimer_init - Initialize alarm timer code
782 * This function initializes the alarm bases and registers
783 * the posix clock ids.
785 static int __init alarmtimer_init(void)
787 struct platform_device *pdev;
790 struct k_clock alarm_clock = {
791 .clock_getres = alarm_clock_getres,
792 .clock_get = alarm_clock_get,
793 .timer_create = alarm_timer_create,
794 .timer_set = alarm_timer_set,
795 .timer_del = alarm_timer_del,
796 .timer_get = alarm_timer_get,
797 .nsleep = alarm_timer_nsleep,
800 alarmtimer_rtc_timer_init();
802 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
803 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
805 /* Initialize alarm bases */
806 alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
807 alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
808 alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
809 alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
810 for (i = 0; i < ALARM_NUMTYPE; i++) {
811 timerqueue_init_head(&alarm_bases[i].timerqueue);
812 spin_lock_init(&alarm_bases[i].lock);
815 error = alarmtimer_rtc_interface_setup();
819 error = platform_driver_register(&alarmtimer_driver);
823 pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
825 error = PTR_ERR(pdev);
828 ws = wakeup_source_register("alarmtimer");
832 platform_driver_unregister(&alarmtimer_driver);
834 alarmtimer_rtc_interface_remove();
837 device_initcall(alarmtimer_init);