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Linux/kernel/time/alarmtimer.c

  1 /*
  2  * Alarmtimer interface
  3  *
  4  * This interface provides a timer which is similarto hrtimers,
  5  * but triggers a RTC alarm if the box is suspend.
  6  *
  7  * This interface is influenced by the Android RTC Alarm timer
  8  * interface.
  9  *
 10  * Copyright (C) 2010 IBM Corperation
 11  *
 12  * Author: John Stultz <john.stultz@linaro.org>
 13  *
 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.
 17  */
 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>
 28 
 29 #define CREATE_TRACE_POINTS
 30 #include <trace/events/alarmtimer.h>
 31 
 32 /**
 33  * struct alarm_base - Alarm timer bases
 34  * @lock:               Lock for syncrhonized access to the base
 35  * @timerqueue:         Timerqueue head managing the list of events
 36  * @gettime:            Function to read the time correlating to the base
 37  * @base_clockid:       clockid for the base
 38  */
 39 static struct alarm_base {
 40         spinlock_t              lock;
 41         struct timerqueue_head  timerqueue;
 42         ktime_t                 (*gettime)(void);
 43         clockid_t               base_clockid;
 44 } alarm_bases[ALARM_NUMTYPE];
 45 
 46 /* freezer information to handle clock_nanosleep triggered wakeups */
 47 static enum alarmtimer_type freezer_alarmtype;
 48 static ktime_t freezer_expires;
 49 static ktime_t freezer_delta;
 50 static DEFINE_SPINLOCK(freezer_delta_lock);
 51 
 52 static struct wakeup_source *ws;
 53 
 54 #ifdef CONFIG_RTC_CLASS
 55 /* rtc timer and device for setting alarm wakeups at suspend */
 56 static struct rtc_timer         rtctimer;
 57 static struct rtc_device        *rtcdev;
 58 static DEFINE_SPINLOCK(rtcdev_lock);
 59 
 60 /**
 61  * alarmtimer_get_rtcdev - Return selected rtcdevice
 62  *
 63  * This function returns the rtc device to use for wakealarms.
 64  * If one has not already been chosen, it checks to see if a
 65  * functional rtc device is available.
 66  */
 67 struct rtc_device *alarmtimer_get_rtcdev(void)
 68 {
 69         unsigned long flags;
 70         struct rtc_device *ret;
 71 
 72         spin_lock_irqsave(&rtcdev_lock, flags);
 73         ret = rtcdev;
 74         spin_unlock_irqrestore(&rtcdev_lock, flags);
 75 
 76         return ret;
 77 }
 78 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
 79 
 80 static int alarmtimer_rtc_add_device(struct device *dev,
 81                                 struct class_interface *class_intf)
 82 {
 83         unsigned long flags;
 84         struct rtc_device *rtc = to_rtc_device(dev);
 85 
 86         if (rtcdev)
 87                 return -EBUSY;
 88 
 89         if (!rtc->ops->set_alarm)
 90                 return -1;
 91         if (!device_may_wakeup(rtc->dev.parent))
 92                 return -1;
 93 
 94         spin_lock_irqsave(&rtcdev_lock, flags);
 95         if (!rtcdev) {
 96                 rtcdev = rtc;
 97                 /* hold a reference so it doesn't go away */
 98                 get_device(dev);
 99         }
100         spin_unlock_irqrestore(&rtcdev_lock, flags);
101         return 0;
102 }
103 
104 static inline void alarmtimer_rtc_timer_init(void)
105 {
106         rtc_timer_init(&rtctimer, NULL, NULL);
107 }
108 
109 static struct class_interface alarmtimer_rtc_interface = {
110         .add_dev = &alarmtimer_rtc_add_device,
111 };
112 
113 static int alarmtimer_rtc_interface_setup(void)
114 {
115         alarmtimer_rtc_interface.class = rtc_class;
116         return class_interface_register(&alarmtimer_rtc_interface);
117 }
118 static void alarmtimer_rtc_interface_remove(void)
119 {
120         class_interface_unregister(&alarmtimer_rtc_interface);
121 }
122 #else
123 struct rtc_device *alarmtimer_get_rtcdev(void)
124 {
125         return NULL;
126 }
127 #define rtcdev (NULL)
128 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
129 static inline void alarmtimer_rtc_interface_remove(void) { }
130 static inline void alarmtimer_rtc_timer_init(void) { }
131 #endif
132 
133 /**
134  * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
135  * @base: pointer to the base where the timer is being run
136  * @alarm: pointer to alarm being enqueued.
137  *
138  * Adds alarm to a alarm_base timerqueue
139  *
140  * Must hold base->lock when calling.
141  */
142 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
143 {
144         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
145                 timerqueue_del(&base->timerqueue, &alarm->node);
146 
147         timerqueue_add(&base->timerqueue, &alarm->node);
148         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
149 }
150 
151 /**
152  * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
153  * @base: pointer to the base where the timer is running
154  * @alarm: pointer to alarm being removed
155  *
156  * Removes alarm to a alarm_base timerqueue
157  *
158  * Must hold base->lock when calling.
159  */
160 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
161 {
162         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
163                 return;
164 
165         timerqueue_del(&base->timerqueue, &alarm->node);
166         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
167 }
168 
169 
170 /**
171  * alarmtimer_fired - Handles alarm hrtimer being fired.
172  * @timer: pointer to hrtimer being run
173  *
174  * When a alarm timer fires, this runs through the timerqueue to
175  * see which alarms expired, and runs those. If there are more alarm
176  * timers queued for the future, we set the hrtimer to fire when
177  * when the next future alarm timer expires.
178  */
179 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
180 {
181         struct alarm *alarm = container_of(timer, struct alarm, timer);
182         struct alarm_base *base = &alarm_bases[alarm->type];
183         unsigned long flags;
184         int ret = HRTIMER_NORESTART;
185         int restart = ALARMTIMER_NORESTART;
186 
187         spin_lock_irqsave(&base->lock, flags);
188         alarmtimer_dequeue(base, alarm);
189         spin_unlock_irqrestore(&base->lock, flags);
190 
191         if (alarm->function)
192                 restart = alarm->function(alarm, base->gettime());
193 
194         spin_lock_irqsave(&base->lock, flags);
195         if (restart != ALARMTIMER_NORESTART) {
196                 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
197                 alarmtimer_enqueue(base, alarm);
198                 ret = HRTIMER_RESTART;
199         }
200         spin_unlock_irqrestore(&base->lock, flags);
201 
202         trace_alarmtimer_fired(alarm, base->gettime());
203         return ret;
204 
205 }
206 
207 ktime_t alarm_expires_remaining(const struct alarm *alarm)
208 {
209         struct alarm_base *base = &alarm_bases[alarm->type];
210         return ktime_sub(alarm->node.expires, base->gettime());
211 }
212 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
213 
214 #ifdef CONFIG_RTC_CLASS
215 /**
216  * alarmtimer_suspend - Suspend time callback
217  * @dev: unused
218  * @state: unused
219  *
220  * When we are going into suspend, we look through the bases
221  * to see which is the soonest timer to expire. We then
222  * set an rtc timer to fire that far into the future, which
223  * will wake us from suspend.
224  */
225 static int alarmtimer_suspend(struct device *dev)
226 {
227         ktime_t min, now, expires;
228         int i, ret, type;
229         struct rtc_device *rtc;
230         unsigned long flags;
231         struct rtc_time tm;
232 
233         spin_lock_irqsave(&freezer_delta_lock, flags);
234         min = freezer_delta;
235         expires = freezer_expires;
236         type = freezer_alarmtype;
237         freezer_delta = 0;
238         spin_unlock_irqrestore(&freezer_delta_lock, flags);
239 
240         rtc = alarmtimer_get_rtcdev();
241         /* If we have no rtcdev, just return */
242         if (!rtc)
243                 return 0;
244 
245         /* Find the soonest timer to expire*/
246         for (i = 0; i < ALARM_NUMTYPE; i++) {
247                 struct alarm_base *base = &alarm_bases[i];
248                 struct timerqueue_node *next;
249                 ktime_t delta;
250 
251                 spin_lock_irqsave(&base->lock, flags);
252                 next = timerqueue_getnext(&base->timerqueue);
253                 spin_unlock_irqrestore(&base->lock, flags);
254                 if (!next)
255                         continue;
256                 delta = ktime_sub(next->expires, base->gettime());
257                 if (!min || (delta < min)) {
258                         expires = next->expires;
259                         min = delta;
260                         type = i;
261                 }
262         }
263         if (min == 0)
264                 return 0;
265 
266         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
267                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
268                 return -EBUSY;
269         }
270 
271         trace_alarmtimer_suspend(expires, type);
272 
273         /* Setup an rtc timer to fire that far in the future */
274         rtc_timer_cancel(rtc, &rtctimer);
275         rtc_read_time(rtc, &tm);
276         now = rtc_tm_to_ktime(tm);
277         now = ktime_add(now, min);
278 
279         /* Set alarm, if in the past reject suspend briefly to handle */
280         ret = rtc_timer_start(rtc, &rtctimer, now, 0);
281         if (ret < 0)
282                 __pm_wakeup_event(ws, MSEC_PER_SEC);
283         return ret;
284 }
285 
286 static int alarmtimer_resume(struct device *dev)
287 {
288         struct rtc_device *rtc;
289 
290         rtc = alarmtimer_get_rtcdev();
291         if (rtc)
292                 rtc_timer_cancel(rtc, &rtctimer);
293         return 0;
294 }
295 
296 #else
297 static int alarmtimer_suspend(struct device *dev)
298 {
299         return 0;
300 }
301 
302 static int alarmtimer_resume(struct device *dev)
303 {
304         return 0;
305 }
306 #endif
307 
308 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
309 {
310         struct alarm_base *base;
311         unsigned long flags;
312         ktime_t delta;
313 
314         switch(type) {
315         case ALARM_REALTIME:
316                 base = &alarm_bases[ALARM_REALTIME];
317                 type = ALARM_REALTIME_FREEZER;
318                 break;
319         case ALARM_BOOTTIME:
320                 base = &alarm_bases[ALARM_BOOTTIME];
321                 type = ALARM_BOOTTIME_FREEZER;
322                 break;
323         default:
324                 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
325                 return;
326         }
327 
328         delta = ktime_sub(absexp, base->gettime());
329 
330         spin_lock_irqsave(&freezer_delta_lock, flags);
331         if (!freezer_delta || (delta < freezer_delta)) {
332                 freezer_delta = delta;
333                 freezer_expires = absexp;
334                 freezer_alarmtype = type;
335         }
336         spin_unlock_irqrestore(&freezer_delta_lock, flags);
337 }
338 
339 
340 /**
341  * alarm_init - Initialize an alarm structure
342  * @alarm: ptr to alarm to be initialized
343  * @type: the type of the alarm
344  * @function: callback that is run when the alarm fires
345  */
346 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
347                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
348 {
349         timerqueue_init(&alarm->node);
350         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
351                         HRTIMER_MODE_ABS);
352         alarm->timer.function = alarmtimer_fired;
353         alarm->function = function;
354         alarm->type = type;
355         alarm->state = ALARMTIMER_STATE_INACTIVE;
356 }
357 EXPORT_SYMBOL_GPL(alarm_init);
358 
359 /**
360  * alarm_start - Sets an absolute alarm to fire
361  * @alarm: ptr to alarm to set
362  * @start: time to run the alarm
363  */
364 void alarm_start(struct alarm *alarm, ktime_t start)
365 {
366         struct alarm_base *base = &alarm_bases[alarm->type];
367         unsigned long flags;
368 
369         spin_lock_irqsave(&base->lock, flags);
370         alarm->node.expires = start;
371         alarmtimer_enqueue(base, alarm);
372         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
373         spin_unlock_irqrestore(&base->lock, flags);
374 
375         trace_alarmtimer_start(alarm, base->gettime());
376 }
377 EXPORT_SYMBOL_GPL(alarm_start);
378 
379 /**
380  * alarm_start_relative - Sets a relative alarm to fire
381  * @alarm: ptr to alarm to set
382  * @start: time relative to now to run the alarm
383  */
384 void alarm_start_relative(struct alarm *alarm, ktime_t start)
385 {
386         struct alarm_base *base = &alarm_bases[alarm->type];
387 
388         start = ktime_add(start, base->gettime());
389         alarm_start(alarm, start);
390 }
391 EXPORT_SYMBOL_GPL(alarm_start_relative);
392 
393 void alarm_restart(struct alarm *alarm)
394 {
395         struct alarm_base *base = &alarm_bases[alarm->type];
396         unsigned long flags;
397 
398         spin_lock_irqsave(&base->lock, flags);
399         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
400         hrtimer_restart(&alarm->timer);
401         alarmtimer_enqueue(base, alarm);
402         spin_unlock_irqrestore(&base->lock, flags);
403 }
404 EXPORT_SYMBOL_GPL(alarm_restart);
405 
406 /**
407  * alarm_try_to_cancel - Tries to cancel an alarm timer
408  * @alarm: ptr to alarm to be canceled
409  *
410  * Returns 1 if the timer was canceled, 0 if it was not running,
411  * and -1 if the callback was running
412  */
413 int alarm_try_to_cancel(struct alarm *alarm)
414 {
415         struct alarm_base *base = &alarm_bases[alarm->type];
416         unsigned long flags;
417         int ret;
418 
419         spin_lock_irqsave(&base->lock, flags);
420         ret = hrtimer_try_to_cancel(&alarm->timer);
421         if (ret >= 0)
422                 alarmtimer_dequeue(base, alarm);
423         spin_unlock_irqrestore(&base->lock, flags);
424 
425         trace_alarmtimer_cancel(alarm, base->gettime());
426         return ret;
427 }
428 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
429 
430 
431 /**
432  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
433  * @alarm: ptr to alarm to be canceled
434  *
435  * Returns 1 if the timer was canceled, 0 if it was not active.
436  */
437 int alarm_cancel(struct alarm *alarm)
438 {
439         for (;;) {
440                 int ret = alarm_try_to_cancel(alarm);
441                 if (ret >= 0)
442                         return ret;
443                 cpu_relax();
444         }
445 }
446 EXPORT_SYMBOL_GPL(alarm_cancel);
447 
448 
449 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
450 {
451         u64 overrun = 1;
452         ktime_t delta;
453 
454         delta = ktime_sub(now, alarm->node.expires);
455 
456         if (delta < 0)
457                 return 0;
458 
459         if (unlikely(delta >= interval)) {
460                 s64 incr = ktime_to_ns(interval);
461 
462                 overrun = ktime_divns(delta, incr);
463 
464                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
465                                                         incr*overrun);
466 
467                 if (alarm->node.expires > now)
468                         return overrun;
469                 /*
470                  * This (and the ktime_add() below) is the
471                  * correction for exact:
472                  */
473                 overrun++;
474         }
475 
476         alarm->node.expires = ktime_add(alarm->node.expires, interval);
477         return overrun;
478 }
479 EXPORT_SYMBOL_GPL(alarm_forward);
480 
481 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
482 {
483         struct alarm_base *base = &alarm_bases[alarm->type];
484 
485         return alarm_forward(alarm, base->gettime(), interval);
486 }
487 EXPORT_SYMBOL_GPL(alarm_forward_now);
488 
489 
490 /**
491  * clock2alarm - helper that converts from clockid to alarmtypes
492  * @clockid: clockid.
493  */
494 static enum alarmtimer_type clock2alarm(clockid_t clockid)
495 {
496         if (clockid == CLOCK_REALTIME_ALARM)
497                 return ALARM_REALTIME;
498         if (clockid == CLOCK_BOOTTIME_ALARM)
499                 return ALARM_BOOTTIME;
500         return -1;
501 }
502 
503 /**
504  * alarm_handle_timer - Callback for posix timers
505  * @alarm: alarm that fired
506  *
507  * Posix timer callback for expired alarm timers.
508  */
509 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
510                                                         ktime_t now)
511 {
512         unsigned long flags;
513         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
514                                                 it.alarm.alarmtimer);
515         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
516 
517         spin_lock_irqsave(&ptr->it_lock, flags);
518         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
519                 if (IS_ENABLED(CONFIG_POSIX_TIMERS) &&
520                     posix_timer_event(ptr, 0) != 0)
521                         ptr->it_overrun++;
522         }
523 
524         /* Re-add periodic timers */
525         if (ptr->it.alarm.interval) {
526                 ptr->it_overrun += alarm_forward(alarm, now,
527                                                 ptr->it.alarm.interval);
528                 result = ALARMTIMER_RESTART;
529         }
530         spin_unlock_irqrestore(&ptr->it_lock, flags);
531 
532         return result;
533 }
534 
535 /**
536  * alarm_clock_getres - posix getres interface
537  * @which_clock: clockid
538  * @tp: timespec to fill
539  *
540  * Returns the granularity of underlying alarm base clock
541  */
542 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
543 {
544         if (!alarmtimer_get_rtcdev())
545                 return -EINVAL;
546 
547         tp->tv_sec = 0;
548         tp->tv_nsec = hrtimer_resolution;
549         return 0;
550 }
551 
552 /**
553  * alarm_clock_get - posix clock_get interface
554  * @which_clock: clockid
555  * @tp: timespec to fill.
556  *
557  * Provides the underlying alarm base time.
558  */
559 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
560 {
561         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
562 
563         if (!alarmtimer_get_rtcdev())
564                 return -EINVAL;
565 
566         *tp = ktime_to_timespec(base->gettime());
567         return 0;
568 }
569 
570 /**
571  * alarm_timer_create - posix timer_create interface
572  * @new_timer: k_itimer pointer to manage
573  *
574  * Initializes the k_itimer structure.
575  */
576 static int alarm_timer_create(struct k_itimer *new_timer)
577 {
578         enum  alarmtimer_type type;
579 
580         if (!alarmtimer_get_rtcdev())
581                 return -ENOTSUPP;
582 
583         if (!capable(CAP_WAKE_ALARM))
584                 return -EPERM;
585 
586         type = clock2alarm(new_timer->it_clock);
587         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
588         return 0;
589 }
590 
591 /**
592  * alarm_timer_get - posix timer_get interface
593  * @new_timer: k_itimer pointer
594  * @cur_setting: itimerspec data to fill
595  *
596  * Copies out the current itimerspec data
597  */
598 static void alarm_timer_get(struct k_itimer *timr,
599                                 struct itimerspec *cur_setting)
600 {
601         ktime_t relative_expiry_time =
602                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
603 
604         if (ktime_to_ns(relative_expiry_time) > 0) {
605                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
606         } else {
607                 cur_setting->it_value.tv_sec = 0;
608                 cur_setting->it_value.tv_nsec = 0;
609         }
610 
611         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
612 }
613 
614 /**
615  * alarm_timer_del - posix timer_del interface
616  * @timr: k_itimer pointer to be deleted
617  *
618  * Cancels any programmed alarms for the given timer.
619  */
620 static int alarm_timer_del(struct k_itimer *timr)
621 {
622         if (!rtcdev)
623                 return -ENOTSUPP;
624 
625         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
626                 return TIMER_RETRY;
627 
628         return 0;
629 }
630 
631 /**
632  * alarm_timer_set - posix timer_set interface
633  * @timr: k_itimer pointer to be deleted
634  * @flags: timer flags
635  * @new_setting: itimerspec to be used
636  * @old_setting: itimerspec being replaced
637  *
638  * Sets the timer to new_setting, and starts the timer.
639  */
640 static int alarm_timer_set(struct k_itimer *timr, int flags,
641                                 struct itimerspec *new_setting,
642                                 struct itimerspec *old_setting)
643 {
644         ktime_t exp;
645 
646         if (!rtcdev)
647                 return -ENOTSUPP;
648 
649         if (flags & ~TIMER_ABSTIME)
650                 return -EINVAL;
651 
652         if (old_setting)
653                 alarm_timer_get(timr, old_setting);
654 
655         /* If the timer was already set, cancel it */
656         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
657                 return TIMER_RETRY;
658 
659         /* start the timer */
660         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
661         exp = timespec_to_ktime(new_setting->it_value);
662         /* Convert (if necessary) to absolute time */
663         if (flags != TIMER_ABSTIME) {
664                 ktime_t now;
665 
666                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
667                 exp = ktime_add(now, exp);
668         }
669 
670         alarm_start(&timr->it.alarm.alarmtimer, exp);
671         return 0;
672 }
673 
674 /**
675  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
676  * @alarm: ptr to alarm that fired
677  *
678  * Wakes up the task that set the alarmtimer
679  */
680 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
681                                                                 ktime_t now)
682 {
683         struct task_struct *task = (struct task_struct *)alarm->data;
684 
685         alarm->data = NULL;
686         if (task)
687                 wake_up_process(task);
688         return ALARMTIMER_NORESTART;
689 }
690 
691 /**
692  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
693  * @alarm: ptr to alarmtimer
694  * @absexp: absolute expiration time
695  *
696  * Sets the alarm timer and sleeps until it is fired or interrupted.
697  */
698 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
699 {
700         alarm->data = (void *)current;
701         do {
702                 set_current_state(TASK_INTERRUPTIBLE);
703                 alarm_start(alarm, absexp);
704                 if (likely(alarm->data))
705                         schedule();
706 
707                 alarm_cancel(alarm);
708         } while (alarm->data && !signal_pending(current));
709 
710         __set_current_state(TASK_RUNNING);
711 
712         return (alarm->data == NULL);
713 }
714 
715 
716 /**
717  * update_rmtp - Update remaining timespec value
718  * @exp: expiration time
719  * @type: timer type
720  * @rmtp: user pointer to remaining timepsec value
721  *
722  * Helper function that fills in rmtp value with time between
723  * now and the exp value
724  */
725 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
726                         struct timespec __user *rmtp)
727 {
728         struct timespec rmt;
729         ktime_t rem;
730 
731         rem = ktime_sub(exp, alarm_bases[type].gettime());
732 
733         if (rem <= 0)
734                 return 0;
735         rmt = ktime_to_timespec(rem);
736 
737         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
738                 return -EFAULT;
739 
740         return 1;
741 
742 }
743 
744 /**
745  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
746  * @restart: ptr to restart block
747  *
748  * Handles restarted clock_nanosleep calls
749  */
750 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
751 {
752         enum  alarmtimer_type type = restart->nanosleep.clockid;
753         ktime_t exp;
754         struct timespec __user  *rmtp;
755         struct alarm alarm;
756         int ret = 0;
757 
758         exp = restart->nanosleep.expires;
759         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
760 
761         if (alarmtimer_do_nsleep(&alarm, exp))
762                 goto out;
763 
764         if (freezing(current))
765                 alarmtimer_freezerset(exp, type);
766 
767         rmtp = restart->nanosleep.rmtp;
768         if (rmtp) {
769                 ret = update_rmtp(exp, type, rmtp);
770                 if (ret <= 0)
771                         goto out;
772         }
773 
774 
775         /* The other values in restart are already filled in */
776         ret = -ERESTART_RESTARTBLOCK;
777 out:
778         return ret;
779 }
780 
781 /**
782  * alarm_timer_nsleep - alarmtimer nanosleep
783  * @which_clock: clockid
784  * @flags: determins abstime or relative
785  * @tsreq: requested sleep time (abs or rel)
786  * @rmtp: remaining sleep time saved
787  *
788  * Handles clock_nanosleep calls against _ALARM clockids
789  */
790 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
791                      struct timespec *tsreq, struct timespec __user *rmtp)
792 {
793         enum  alarmtimer_type type = clock2alarm(which_clock);
794         struct alarm alarm;
795         ktime_t exp;
796         int ret = 0;
797         struct restart_block *restart;
798 
799         if (!alarmtimer_get_rtcdev())
800                 return -ENOTSUPP;
801 
802         if (flags & ~TIMER_ABSTIME)
803                 return -EINVAL;
804 
805         if (!capable(CAP_WAKE_ALARM))
806                 return -EPERM;
807 
808         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
809 
810         exp = timespec_to_ktime(*tsreq);
811         /* Convert (if necessary) to absolute time */
812         if (flags != TIMER_ABSTIME) {
813                 ktime_t now = alarm_bases[type].gettime();
814                 exp = ktime_add(now, exp);
815         }
816 
817         if (alarmtimer_do_nsleep(&alarm, exp))
818                 goto out;
819 
820         if (freezing(current))
821                 alarmtimer_freezerset(exp, type);
822 
823         /* abs timers don't set remaining time or restart */
824         if (flags == TIMER_ABSTIME) {
825                 ret = -ERESTARTNOHAND;
826                 goto out;
827         }
828 
829         if (rmtp) {
830                 ret = update_rmtp(exp, type, rmtp);
831                 if (ret <= 0)
832                         goto out;
833         }
834 
835         restart = &current->restart_block;
836         restart->fn = alarm_timer_nsleep_restart;
837         restart->nanosleep.clockid = type;
838         restart->nanosleep.expires = exp;
839         restart->nanosleep.rmtp = rmtp;
840         ret = -ERESTART_RESTARTBLOCK;
841 
842 out:
843         return ret;
844 }
845 
846 
847 /* Suspend hook structures */
848 static const struct dev_pm_ops alarmtimer_pm_ops = {
849         .suspend = alarmtimer_suspend,
850         .resume = alarmtimer_resume,
851 };
852 
853 static struct platform_driver alarmtimer_driver = {
854         .driver = {
855                 .name = "alarmtimer",
856                 .pm = &alarmtimer_pm_ops,
857         }
858 };
859 
860 /**
861  * alarmtimer_init - Initialize alarm timer code
862  *
863  * This function initializes the alarm bases and registers
864  * the posix clock ids.
865  */
866 static int __init alarmtimer_init(void)
867 {
868         struct platform_device *pdev;
869         int error = 0;
870         int i;
871         struct k_clock alarm_clock = {
872                 .clock_getres   = alarm_clock_getres,
873                 .clock_get      = alarm_clock_get,
874                 .timer_create   = alarm_timer_create,
875                 .timer_set      = alarm_timer_set,
876                 .timer_del      = alarm_timer_del,
877                 .timer_get      = alarm_timer_get,
878                 .nsleep         = alarm_timer_nsleep,
879         };
880 
881         alarmtimer_rtc_timer_init();
882 
883         if (IS_ENABLED(CONFIG_POSIX_TIMERS)) {
884                 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
885                 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
886         }
887 
888         /* Initialize alarm bases */
889         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
890         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
891         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
892         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
893         for (i = 0; i < ALARM_NUMTYPE; i++) {
894                 timerqueue_init_head(&alarm_bases[i].timerqueue);
895                 spin_lock_init(&alarm_bases[i].lock);
896         }
897 
898         error = alarmtimer_rtc_interface_setup();
899         if (error)
900                 return error;
901 
902         error = platform_driver_register(&alarmtimer_driver);
903         if (error)
904                 goto out_if;
905 
906         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
907         if (IS_ERR(pdev)) {
908                 error = PTR_ERR(pdev);
909                 goto out_drv;
910         }
911         ws = wakeup_source_register("alarmtimer");
912         return 0;
913 
914 out_drv:
915         platform_driver_unregister(&alarmtimer_driver);
916 out_if:
917         alarmtimer_rtc_interface_remove();
918         return error;
919 }
920 device_initcall(alarmtimer_init);
921 

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