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
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* Author: John Stultz <john.stultz@linaro.org>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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#include <linux/time.h>
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#include <linux/hrtimer.h>
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#include <linux/timerqueue.h>
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#include <linux/rtc.h>
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#include <linux/alarmtimer.h>
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#include <linux/mutex.h>
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#include <linux/platform_device.h>
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#include <linux/posix-timers.h>
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#include <linux/workqueue.h>
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#include <linux/freezer.h>
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* struct alarm_base - Alarm timer bases
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* @lock: Lock for syncrhonized access to the base
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* @timerqueue: Timerqueue head managing the list of events
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* @timer: hrtimer used to schedule events while running
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* @gettime: Function to read the time correlating to the base
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* @base_clockid: clockid for the base
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static struct alarm_base {
39
struct timerqueue_head timerqueue;
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ktime_t (*gettime)(void);
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clockid_t base_clockid;
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} alarm_bases[ALARM_NUMTYPE];
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/* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
46
static ktime_t freezer_delta;
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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;
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static DEFINE_SPINLOCK(rtcdev_lock);
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* alarmtimer_get_rtcdev - Return selected rtcdevice
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* This function returns the rtc device to use for wakealarms.
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* If one has not already been chosen, it checks to see if a
60
* functional rtc device is available.
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static struct rtc_device *alarmtimer_get_rtcdev(void)
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struct rtc_device *ret;
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spin_lock_irqsave(&rtcdev_lock, flags);
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spin_unlock_irqrestore(&rtcdev_lock, flags);
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static int alarmtimer_rtc_add_device(struct device *dev,
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struct class_interface *class_intf)
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struct rtc_device *rtc = to_rtc_device(dev);
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if (!rtc->ops->set_alarm)
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if (!device_may_wakeup(rtc->dev.parent))
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spin_lock_irqsave(&rtcdev_lock, flags);
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/* hold a reference so it doesn't go away */
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spin_unlock_irqrestore(&rtcdev_lock, flags);
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static struct class_interface alarmtimer_rtc_interface = {
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.add_dev = &alarmtimer_rtc_add_device,
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static int alarmtimer_rtc_interface_setup(void)
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alarmtimer_rtc_interface.class = rtc_class;
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return class_interface_register(&alarmtimer_rtc_interface);
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static void alarmtimer_rtc_interface_remove(void)
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class_interface_unregister(&alarmtimer_rtc_interface);
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static inline struct rtc_device *alarmtimer_get_rtcdev(void)
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#define rtcdev (NULL)
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static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
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static inline void alarmtimer_rtc_interface_remove(void) { }
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* alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
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* @base: pointer to the base where the timer is being run
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* @alarm: pointer to alarm being enqueued.
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* Adds alarm to a alarm_base timerqueue and if necessary sets
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* Must hold base->lock when calling.
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static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
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timerqueue_add(&base->timerqueue, &alarm->node);
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alarm->state |= ALARMTIMER_STATE_ENQUEUED;
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if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
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hrtimer_try_to_cancel(&base->timer);
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hrtimer_start(&base->timer, alarm->node.expires,
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* alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue
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* @base: pointer to the base where the timer is running
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* @alarm: pointer to alarm being removed
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* Removes alarm to a alarm_base timerqueue and if necessary sets
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* a new timer to run.
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* Must hold base->lock when calling.
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static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
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struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
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if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
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timerqueue_del(&base->timerqueue, &alarm->node);
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alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
164
if (next == &alarm->node) {
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hrtimer_try_to_cancel(&base->timer);
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next = timerqueue_getnext(&base->timerqueue);
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hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
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* alarmtimer_fired - Handles alarm hrtimer being fired.
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* @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
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* when the next future alarm timer expires.
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static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
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struct alarm_base *base = container_of(timer, struct alarm_base, timer);
186
struct timerqueue_node *next;
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int ret = HRTIMER_NORESTART;
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int restart = ALARMTIMER_NORESTART;
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spin_lock_irqsave(&base->lock, flags);
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now = base->gettime();
194
while ((next = timerqueue_getnext(&base->timerqueue))) {
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ktime_t expired = next->expires;
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if (expired.tv64 > now.tv64)
201
alarm = container_of(next, struct alarm, node);
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timerqueue_del(&base->timerqueue, &alarm->node);
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alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
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alarm->state |= ALARMTIMER_STATE_CALLBACK;
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spin_unlock_irqrestore(&base->lock, flags);
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restart = alarm->function(alarm, now);
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spin_lock_irqsave(&base->lock, flags);
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alarm->state &= ~ALARMTIMER_STATE_CALLBACK;
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if (restart != ALARMTIMER_NORESTART) {
214
timerqueue_add(&base->timerqueue, &alarm->node);
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alarm->state |= ALARMTIMER_STATE_ENQUEUED;
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hrtimer_set_expires(&base->timer, next->expires);
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ret = HRTIMER_RESTART;
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spin_unlock_irqrestore(&base->lock, flags);
229
#ifdef CONFIG_RTC_CLASS
231
* alarmtimer_suspend - Suspend time callback
235
* When we are going into suspend, we look through the bases
236
* to see which is the soonest timer to expire. We then
237
* set an rtc timer to fire that far into the future, which
238
* will wake us from suspend.
240
static int alarmtimer_suspend(struct device *dev)
245
struct rtc_device *rtc;
248
spin_lock_irqsave(&freezer_delta_lock, flags);
250
freezer_delta = ktime_set(0, 0);
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spin_unlock_irqrestore(&freezer_delta_lock, flags);
253
rtc = alarmtimer_get_rtcdev();
254
/* If we have no rtcdev, just return */
258
/* Find the soonest timer to expire*/
259
for (i = 0; i < ALARM_NUMTYPE; i++) {
260
struct alarm_base *base = &alarm_bases[i];
261
struct timerqueue_node *next;
264
spin_lock_irqsave(&base->lock, flags);
265
next = timerqueue_getnext(&base->timerqueue);
266
spin_unlock_irqrestore(&base->lock, flags);
269
delta = ktime_sub(next->expires, base->gettime());
270
if (!min.tv64 || (delta.tv64 < min.tv64))
276
/* XXX - Should we enforce a minimum sleep time? */
277
WARN_ON(min.tv64 < NSEC_PER_SEC);
279
/* Setup an rtc timer to fire that far in the future */
280
rtc_timer_cancel(rtc, &rtctimer);
281
rtc_read_time(rtc, &tm);
282
now = rtc_tm_to_ktime(tm);
283
now = ktime_add(now, min);
285
rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
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static int alarmtimer_suspend(struct device *dev)
296
static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
300
struct alarm_base *base = &alarm_bases[type];
302
delta = ktime_sub(absexp, base->gettime());
304
spin_lock_irqsave(&freezer_delta_lock, flags);
305
if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
306
freezer_delta = delta;
307
spin_unlock_irqrestore(&freezer_delta_lock, flags);
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* alarm_init - Initialize an alarm structure
313
* @alarm: ptr to alarm to be initialized
314
* @type: the type of the alarm
315
* @function: callback that is run when the alarm fires
317
void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
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enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
320
timerqueue_init(&alarm->node);
321
alarm->function = function;
323
alarm->state = ALARMTIMER_STATE_INACTIVE;
327
* alarm_start - Sets an alarm to fire
328
* @alarm: ptr to alarm to set
329
* @start: time to run the alarm
331
void alarm_start(struct alarm *alarm, ktime_t start)
333
struct alarm_base *base = &alarm_bases[alarm->type];
336
spin_lock_irqsave(&base->lock, flags);
337
if (alarmtimer_active(alarm))
338
alarmtimer_remove(base, alarm);
339
alarm->node.expires = start;
340
alarmtimer_enqueue(base, alarm);
341
spin_unlock_irqrestore(&base->lock, flags);
345
* alarm_try_to_cancel - Tries to cancel an alarm timer
346
* @alarm: ptr to alarm to be canceled
348
* Returns 1 if the timer was canceled, 0 if it was not running,
349
* and -1 if the callback was running
351
int alarm_try_to_cancel(struct alarm *alarm)
353
struct alarm_base *base = &alarm_bases[alarm->type];
356
spin_lock_irqsave(&base->lock, flags);
358
if (alarmtimer_callback_running(alarm))
361
if (alarmtimer_is_queued(alarm)) {
362
alarmtimer_remove(base, alarm);
367
spin_unlock_irqrestore(&base->lock, flags);
373
* alarm_cancel - Spins trying to cancel an alarm timer until it is done
374
* @alarm: ptr to alarm to be canceled
376
* Returns 1 if the timer was canceled, 0 if it was not active.
378
int alarm_cancel(struct alarm *alarm)
381
int ret = alarm_try_to_cancel(alarm);
389
u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
394
delta = ktime_sub(now, alarm->node.expires);
399
if (unlikely(delta.tv64 >= interval.tv64)) {
400
s64 incr = ktime_to_ns(interval);
402
overrun = ktime_divns(delta, incr);
404
alarm->node.expires = ktime_add_ns(alarm->node.expires,
407
if (alarm->node.expires.tv64 > now.tv64)
410
* This (and the ktime_add() below) is the
411
* correction for exact:
416
alarm->node.expires = ktime_add(alarm->node.expires, interval);
424
* clock2alarm - helper that converts from clockid to alarmtypes
427
static enum alarmtimer_type clock2alarm(clockid_t clockid)
429
if (clockid == CLOCK_REALTIME_ALARM)
430
return ALARM_REALTIME;
431
if (clockid == CLOCK_BOOTTIME_ALARM)
432
return ALARM_BOOTTIME;
437
* alarm_handle_timer - Callback for posix timers
438
* @alarm: alarm that fired
440
* Posix timer callback for expired alarm timers.
442
static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
445
struct k_itimer *ptr = container_of(alarm, struct k_itimer,
446
it.alarm.alarmtimer);
447
if (posix_timer_event(ptr, 0) != 0)
450
/* Re-add periodic timers */
451
if (ptr->it.alarm.interval.tv64) {
452
ptr->it_overrun += alarm_forward(alarm, now,
453
ptr->it.alarm.interval);
454
return ALARMTIMER_RESTART;
456
return ALARMTIMER_NORESTART;
460
* alarm_clock_getres - posix getres interface
461
* @which_clock: clockid
462
* @tp: timespec to fill
464
* Returns the granularity of underlying alarm base clock
466
static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
468
clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
470
if (!alarmtimer_get_rtcdev())
473
return hrtimer_get_res(baseid, tp);
477
* alarm_clock_get - posix clock_get interface
478
* @which_clock: clockid
479
* @tp: timespec to fill.
481
* Provides the underlying alarm base time.
483
static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
485
struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
487
if (!alarmtimer_get_rtcdev())
490
*tp = ktime_to_timespec(base->gettime());
495
* alarm_timer_create - posix timer_create interface
496
* @new_timer: k_itimer pointer to manage
498
* Initializes the k_itimer structure.
500
static int alarm_timer_create(struct k_itimer *new_timer)
502
enum alarmtimer_type type;
503
struct alarm_base *base;
505
if (!alarmtimer_get_rtcdev())
508
if (!capable(CAP_WAKE_ALARM))
511
type = clock2alarm(new_timer->it_clock);
512
base = &alarm_bases[type];
513
alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
518
* alarm_timer_get - posix timer_get interface
519
* @new_timer: k_itimer pointer
520
* @cur_setting: itimerspec data to fill
522
* Copies the itimerspec data out from the k_itimer
524
static void alarm_timer_get(struct k_itimer *timr,
525
struct itimerspec *cur_setting)
527
memset(cur_setting, 0, sizeof(struct itimerspec));
529
cur_setting->it_interval =
530
ktime_to_timespec(timr->it.alarm.interval);
531
cur_setting->it_value =
532
ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
537
* alarm_timer_del - posix timer_del interface
538
* @timr: k_itimer pointer to be deleted
540
* Cancels any programmed alarms for the given timer.
542
static int alarm_timer_del(struct k_itimer *timr)
547
if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
554
* alarm_timer_set - posix timer_set interface
555
* @timr: k_itimer pointer to be deleted
556
* @flags: timer flags
557
* @new_setting: itimerspec to be used
558
* @old_setting: itimerspec being replaced
560
* Sets the timer to new_setting, and starts the timer.
562
static int alarm_timer_set(struct k_itimer *timr, int flags,
563
struct itimerspec *new_setting,
564
struct itimerspec *old_setting)
570
alarm_timer_get(timr, old_setting);
572
/* If the timer was already set, cancel it */
573
if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
576
/* start the timer */
577
timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
578
alarm_start(&timr->it.alarm.alarmtimer,
579
timespec_to_ktime(new_setting->it_value));
584
* alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
585
* @alarm: ptr to alarm that fired
587
* Wakes up the task that set the alarmtimer
589
static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
592
struct task_struct *task = (struct task_struct *)alarm->data;
596
wake_up_process(task);
597
return ALARMTIMER_NORESTART;
601
* alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
602
* @alarm: ptr to alarmtimer
603
* @absexp: absolute expiration time
605
* Sets the alarm timer and sleeps until it is fired or interrupted.
607
static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
609
alarm->data = (void *)current;
611
set_current_state(TASK_INTERRUPTIBLE);
612
alarm_start(alarm, absexp);
613
if (likely(alarm->data))
617
} while (alarm->data && !signal_pending(current));
619
__set_current_state(TASK_RUNNING);
621
return (alarm->data == NULL);
626
* update_rmtp - Update remaining timespec value
627
* @exp: expiration time
629
* @rmtp: user pointer to remaining timepsec value
631
* Helper function that fills in rmtp value with time between
632
* now and the exp value
634
static int update_rmtp(ktime_t exp, enum alarmtimer_type type,
635
struct timespec __user *rmtp)
640
rem = ktime_sub(exp, alarm_bases[type].gettime());
644
rmt = ktime_to_timespec(rem);
646
if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
654
* alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
655
* @restart: ptr to restart block
657
* Handles restarted clock_nanosleep calls
659
static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
661
enum alarmtimer_type type = restart->nanosleep.clockid;
663
struct timespec __user *rmtp;
667
exp.tv64 = restart->nanosleep.expires;
668
alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
670
if (alarmtimer_do_nsleep(&alarm, exp))
673
if (freezing(current))
674
alarmtimer_freezerset(exp, type);
676
rmtp = restart->nanosleep.rmtp;
678
ret = update_rmtp(exp, type, rmtp);
684
/* The other values in restart are already filled in */
685
ret = -ERESTART_RESTARTBLOCK;
691
* alarm_timer_nsleep - alarmtimer nanosleep
692
* @which_clock: clockid
693
* @flags: determins abstime or relative
694
* @tsreq: requested sleep time (abs or rel)
695
* @rmtp: remaining sleep time saved
697
* Handles clock_nanosleep calls against _ALARM clockids
699
static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
700
struct timespec *tsreq, struct timespec __user *rmtp)
702
enum alarmtimer_type type = clock2alarm(which_clock);
706
struct restart_block *restart;
708
if (!alarmtimer_get_rtcdev())
711
if (!capable(CAP_WAKE_ALARM))
714
alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
716
exp = timespec_to_ktime(*tsreq);
717
/* Convert (if necessary) to absolute time */
718
if (flags != TIMER_ABSTIME) {
719
ktime_t now = alarm_bases[type].gettime();
720
exp = ktime_add(now, exp);
723
if (alarmtimer_do_nsleep(&alarm, exp))
726
if (freezing(current))
727
alarmtimer_freezerset(exp, type);
729
/* abs timers don't set remaining time or restart */
730
if (flags == TIMER_ABSTIME) {
731
ret = -ERESTARTNOHAND;
736
ret = update_rmtp(exp, type, rmtp);
741
restart = ¤t_thread_info()->restart_block;
742
restart->fn = alarm_timer_nsleep_restart;
743
restart->nanosleep.clockid = type;
744
restart->nanosleep.expires = exp.tv64;
745
restart->nanosleep.rmtp = rmtp;
746
ret = -ERESTART_RESTARTBLOCK;
753
/* Suspend hook structures */
754
static const struct dev_pm_ops alarmtimer_pm_ops = {
755
.suspend = alarmtimer_suspend,
758
static struct platform_driver alarmtimer_driver = {
760
.name = "alarmtimer",
761
.pm = &alarmtimer_pm_ops,
766
* alarmtimer_init - Initialize alarm timer code
768
* This function initializes the alarm bases and registers
769
* the posix clock ids.
771
static int __init alarmtimer_init(void)
773
struct platform_device *pdev;
776
struct k_clock alarm_clock = {
777
.clock_getres = alarm_clock_getres,
778
.clock_get = alarm_clock_get,
779
.timer_create = alarm_timer_create,
780
.timer_set = alarm_timer_set,
781
.timer_del = alarm_timer_del,
782
.timer_get = alarm_timer_get,
783
.nsleep = alarm_timer_nsleep,
786
posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
787
posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
789
/* Initialize alarm bases */
790
alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
791
alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
792
alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
793
alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
794
for (i = 0; i < ALARM_NUMTYPE; i++) {
795
timerqueue_init_head(&alarm_bases[i].timerqueue);
796
spin_lock_init(&alarm_bases[i].lock);
797
hrtimer_init(&alarm_bases[i].timer,
798
alarm_bases[i].base_clockid,
800
alarm_bases[i].timer.function = alarmtimer_fired;
803
error = alarmtimer_rtc_interface_setup();
807
error = platform_driver_register(&alarmtimer_driver);
811
pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
813
error = PTR_ERR(pdev);
819
platform_driver_unregister(&alarmtimer_driver);
821
alarmtimer_rtc_interface_remove();
824
device_initcall(alarmtimer_init);