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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 /**
 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
 36  */
 37 static struct alarm_base {
 38         spinlock_t              lock;
 39         struct timerqueue_head  timerqueue;
 40         ktime_t                 (*gettime)(void);
 41         clockid_t               base_clockid;
 42 } alarm_bases[ALARM_NUMTYPE];
 43 
 44 /* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
 45 static ktime_t freezer_delta;
 46 static DEFINE_SPINLOCK(freezer_delta_lock);
 47 
 48 static struct wakeup_source *ws;
 49 
 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);
 55 
 56 /**
 57  * alarmtimer_get_rtcdev - Return selected rtcdevice
 58  *
 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.
 62  */
 63 struct rtc_device *alarmtimer_get_rtcdev(void)
 64 {
 65         unsigned long flags;
 66         struct rtc_device *ret;
 67 
 68         spin_lock_irqsave(&rtcdev_lock, flags);
 69         ret = rtcdev;
 70         spin_unlock_irqrestore(&rtcdev_lock, flags);
 71 
 72         return ret;
 73 }
 74 
 75 
 76 static int alarmtimer_rtc_add_device(struct device *dev,
 77                                 struct class_interface *class_intf)
 78 {
 79         unsigned long flags;
 80         struct rtc_device *rtc = to_rtc_device(dev);
 81 
 82         if (rtcdev)
 83                 return -EBUSY;
 84 
 85         if (!rtc->ops->set_alarm)
 86                 return -1;
 87         if (!device_may_wakeup(rtc->dev.parent))
 88                 return -1;
 89 
 90         spin_lock_irqsave(&rtcdev_lock, flags);
 91         if (!rtcdev) {
 92                 rtcdev = rtc;
 93                 /* hold a reference so it doesn't go away */
 94                 get_device(dev);
 95         }
 96         spin_unlock_irqrestore(&rtcdev_lock, flags);
 97         return 0;
 98 }
 99 
100 static inline void alarmtimer_rtc_timer_init(void)
101 {
102         rtc_timer_init(&rtctimer, NULL, NULL);
103 }
104 
105 static struct class_interface alarmtimer_rtc_interface = {
106         .add_dev = &alarmtimer_rtc_add_device,
107 };
108 
109 static int alarmtimer_rtc_interface_setup(void)
110 {
111         alarmtimer_rtc_interface.class = rtc_class;
112         return class_interface_register(&alarmtimer_rtc_interface);
113 }
114 static void alarmtimer_rtc_interface_remove(void)
115 {
116         class_interface_unregister(&alarmtimer_rtc_interface);
117 }
118 #else
119 struct rtc_device *alarmtimer_get_rtcdev(void)
120 {
121         return NULL;
122 }
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) { }
127 #endif
128 
129 /**
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.
133  *
134  * Adds alarm to a alarm_base timerqueue
135  *
136  * Must hold base->lock when calling.
137  */
138 static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
139 {
140         if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
141                 timerqueue_del(&base->timerqueue, &alarm->node);
142 
143         timerqueue_add(&base->timerqueue, &alarm->node);
144         alarm->state |= ALARMTIMER_STATE_ENQUEUED;
145 }
146 
147 /**
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
151  *
152  * Removes alarm to a alarm_base timerqueue
153  *
154  * Must hold base->lock when calling.
155  */
156 static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
157 {
158         if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
159                 return;
160 
161         timerqueue_del(&base->timerqueue, &alarm->node);
162         alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
163 }
164 
165 
166 /**
167  * alarmtimer_fired - Handles alarm hrtimer being fired.
168  * @timer: pointer to hrtimer being run
169  *
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.
174  */
175 static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
176 {
177         struct alarm *alarm = container_of(timer, struct alarm, timer);
178         struct alarm_base *base = &alarm_bases[alarm->type];
179         unsigned long flags;
180         int ret = HRTIMER_NORESTART;
181         int restart = ALARMTIMER_NORESTART;
182 
183         spin_lock_irqsave(&base->lock, flags);
184         alarmtimer_dequeue(base, alarm);
185         spin_unlock_irqrestore(&base->lock, flags);
186 
187         if (alarm->function)
188                 restart = alarm->function(alarm, base->gettime());
189 
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;
195         }
196         spin_unlock_irqrestore(&base->lock, flags);
197 
198         return ret;
199 
200 }
201 
202 ktime_t alarm_expires_remaining(const struct alarm *alarm)
203 {
204         struct alarm_base *base = &alarm_bases[alarm->type];
205         return ktime_sub(alarm->node.expires, base->gettime());
206 }
207 EXPORT_SYMBOL_GPL(alarm_expires_remaining);
208 
209 #ifdef CONFIG_RTC_CLASS
210 /**
211  * alarmtimer_suspend - Suspend time callback
212  * @dev: unused
213  * @state: unused
214  *
215  * When we are going into suspend, we look through the bases
216  * to see which is the soonest timer to expire. We then
217  * set an rtc timer to fire that far into the future, which
218  * will wake us from suspend.
219  */
220 static int alarmtimer_suspend(struct device *dev)
221 {
222         struct rtc_time tm;
223         ktime_t min, now;
224         unsigned long flags;
225         struct rtc_device *rtc;
226         int i;
227         int ret;
228 
229         spin_lock_irqsave(&freezer_delta_lock, flags);
230         min = freezer_delta;
231         freezer_delta = ktime_set(0, 0);
232         spin_unlock_irqrestore(&freezer_delta_lock, flags);
233 
234         rtc = alarmtimer_get_rtcdev();
235         /* If we have no rtcdev, just return */
236         if (!rtc)
237                 return 0;
238 
239         /* Find the soonest timer to expire*/
240         for (i = 0; i < ALARM_NUMTYPE; i++) {
241                 struct alarm_base *base = &alarm_bases[i];
242                 struct timerqueue_node *next;
243                 ktime_t delta;
244 
245                 spin_lock_irqsave(&base->lock, flags);
246                 next = timerqueue_getnext(&base->timerqueue);
247                 spin_unlock_irqrestore(&base->lock, flags);
248                 if (!next)
249                         continue;
250                 delta = ktime_sub(next->expires, base->gettime());
251                 if (!min.tv64 || (delta.tv64 < min.tv64))
252                         min = delta;
253         }
254         if (min.tv64 == 0)
255                 return 0;
256 
257         if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
258                 __pm_wakeup_event(ws, 2 * MSEC_PER_SEC);
259                 return -EBUSY;
260         }
261 
262         /* Setup an rtc timer to fire that far in the future */
263         rtc_timer_cancel(rtc, &rtctimer);
264         rtc_read_time(rtc, &tm);
265         now = rtc_tm_to_ktime(tm);
266         now = ktime_add(now, min);
267 
268         /* Set alarm, if in the past reject suspend briefly to handle */
269         ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
270         if (ret < 0)
271                 __pm_wakeup_event(ws, MSEC_PER_SEC);
272         return ret;
273 }
274 #else
275 static int alarmtimer_suspend(struct device *dev)
276 {
277         return 0;
278 }
279 #endif
280 
281 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
282 {
283         ktime_t delta;
284         unsigned long flags;
285         struct alarm_base *base = &alarm_bases[type];
286 
287         delta = ktime_sub(absexp, base->gettime());
288 
289         spin_lock_irqsave(&freezer_delta_lock, flags);
290         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
291                 freezer_delta = delta;
292         spin_unlock_irqrestore(&freezer_delta_lock, flags);
293 }
294 
295 
296 /**
297  * alarm_init - Initialize an alarm structure
298  * @alarm: ptr to alarm to be initialized
299  * @type: the type of the alarm
300  * @function: callback that is run when the alarm fires
301  */
302 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
303                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
304 {
305         timerqueue_init(&alarm->node);
306         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
307                         HRTIMER_MODE_ABS);
308         alarm->timer.function = alarmtimer_fired;
309         alarm->function = function;
310         alarm->type = type;
311         alarm->state = ALARMTIMER_STATE_INACTIVE;
312 }
313 EXPORT_SYMBOL_GPL(alarm_init);
314 
315 /**
316  * alarm_start - Sets an absolute alarm to fire
317  * @alarm: ptr to alarm to set
318  * @start: time to run the alarm
319  */
320 int alarm_start(struct alarm *alarm, ktime_t start)
321 {
322         struct alarm_base *base = &alarm_bases[alarm->type];
323         unsigned long flags;
324         int ret;
325 
326         spin_lock_irqsave(&base->lock, flags);
327         alarm->node.expires = start;
328         alarmtimer_enqueue(base, alarm);
329         ret = hrtimer_start(&alarm->timer, alarm->node.expires,
330                                 HRTIMER_MODE_ABS);
331         spin_unlock_irqrestore(&base->lock, flags);
332         return ret;
333 }
334 EXPORT_SYMBOL_GPL(alarm_start);
335 
336 /**
337  * alarm_start_relative - Sets a relative alarm to fire
338  * @alarm: ptr to alarm to set
339  * @start: time relative to now to run the alarm
340  */
341 int alarm_start_relative(struct alarm *alarm, ktime_t start)
342 {
343         struct alarm_base *base = &alarm_bases[alarm->type];
344 
345         start = ktime_add(start, base->gettime());
346         return alarm_start(alarm, start);
347 }
348 EXPORT_SYMBOL_GPL(alarm_start_relative);
349 
350 void alarm_restart(struct alarm *alarm)
351 {
352         struct alarm_base *base = &alarm_bases[alarm->type];
353         unsigned long flags;
354 
355         spin_lock_irqsave(&base->lock, flags);
356         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
357         hrtimer_restart(&alarm->timer);
358         alarmtimer_enqueue(base, alarm);
359         spin_unlock_irqrestore(&base->lock, flags);
360 }
361 EXPORT_SYMBOL_GPL(alarm_restart);
362 
363 /**
364  * alarm_try_to_cancel - Tries to cancel an alarm timer
365  * @alarm: ptr to alarm to be canceled
366  *
367  * Returns 1 if the timer was canceled, 0 if it was not running,
368  * and -1 if the callback was running
369  */
370 int alarm_try_to_cancel(struct alarm *alarm)
371 {
372         struct alarm_base *base = &alarm_bases[alarm->type];
373         unsigned long flags;
374         int ret;
375 
376         spin_lock_irqsave(&base->lock, flags);
377         ret = hrtimer_try_to_cancel(&alarm->timer);
378         if (ret >= 0)
379                 alarmtimer_dequeue(base, alarm);
380         spin_unlock_irqrestore(&base->lock, flags);
381         return ret;
382 }
383 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
384 
385 
386 /**
387  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
388  * @alarm: ptr to alarm to be canceled
389  *
390  * Returns 1 if the timer was canceled, 0 if it was not active.
391  */
392 int alarm_cancel(struct alarm *alarm)
393 {
394         for (;;) {
395                 int ret = alarm_try_to_cancel(alarm);
396                 if (ret >= 0)
397                         return ret;
398                 cpu_relax();
399         }
400 }
401 EXPORT_SYMBOL_GPL(alarm_cancel);
402 
403 
404 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
405 {
406         u64 overrun = 1;
407         ktime_t delta;
408 
409         delta = ktime_sub(now, alarm->node.expires);
410 
411         if (delta.tv64 < 0)
412                 return 0;
413 
414         if (unlikely(delta.tv64 >= interval.tv64)) {
415                 s64 incr = ktime_to_ns(interval);
416 
417                 overrun = ktime_divns(delta, incr);
418 
419                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
420                                                         incr*overrun);
421 
422                 if (alarm->node.expires.tv64 > now.tv64)
423                         return overrun;
424                 /*
425                  * This (and the ktime_add() below) is the
426                  * correction for exact:
427                  */
428                 overrun++;
429         }
430 
431         alarm->node.expires = ktime_add(alarm->node.expires, interval);
432         return overrun;
433 }
434 EXPORT_SYMBOL_GPL(alarm_forward);
435 
436 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
437 {
438         struct alarm_base *base = &alarm_bases[alarm->type];
439 
440         return alarm_forward(alarm, base->gettime(), interval);
441 }
442 EXPORT_SYMBOL_GPL(alarm_forward_now);
443 
444 
445 /**
446  * clock2alarm - helper that converts from clockid to alarmtypes
447  * @clockid: clockid.
448  */
449 static enum alarmtimer_type clock2alarm(clockid_t clockid)
450 {
451         if (clockid == CLOCK_REALTIME_ALARM)
452                 return ALARM_REALTIME;
453         if (clockid == CLOCK_BOOTTIME_ALARM)
454                 return ALARM_BOOTTIME;
455         return -1;
456 }
457 
458 /**
459  * alarm_handle_timer - Callback for posix timers
460  * @alarm: alarm that fired
461  *
462  * Posix timer callback for expired alarm timers.
463  */
464 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
465                                                         ktime_t now)
466 {
467         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
468                                                 it.alarm.alarmtimer);
469         if (posix_timer_event(ptr, 0) != 0)
470                 ptr->it_overrun++;
471 
472         /* Re-add periodic timers */
473         if (ptr->it.alarm.interval.tv64) {
474                 ptr->it_overrun += alarm_forward(alarm, now,
475                                                 ptr->it.alarm.interval);
476                 return ALARMTIMER_RESTART;
477         }
478         return ALARMTIMER_NORESTART;
479 }
480 
481 /**
482  * alarm_clock_getres - posix getres interface
483  * @which_clock: clockid
484  * @tp: timespec to fill
485  *
486  * Returns the granularity of underlying alarm base clock
487  */
488 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
489 {
490         clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
491 
492         if (!alarmtimer_get_rtcdev())
493                 return -EINVAL;
494 
495         return hrtimer_get_res(baseid, tp);
496 }
497 
498 /**
499  * alarm_clock_get - posix clock_get interface
500  * @which_clock: clockid
501  * @tp: timespec to fill.
502  *
503  * Provides the underlying alarm base time.
504  */
505 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
506 {
507         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
508 
509         if (!alarmtimer_get_rtcdev())
510                 return -EINVAL;
511 
512         *tp = ktime_to_timespec(base->gettime());
513         return 0;
514 }
515 
516 /**
517  * alarm_timer_create - posix timer_create interface
518  * @new_timer: k_itimer pointer to manage
519  *
520  * Initializes the k_itimer structure.
521  */
522 static int alarm_timer_create(struct k_itimer *new_timer)
523 {
524         enum  alarmtimer_type type;
525         struct alarm_base *base;
526 
527         if (!alarmtimer_get_rtcdev())
528                 return -ENOTSUPP;
529 
530         if (!capable(CAP_WAKE_ALARM))
531                 return -EPERM;
532 
533         type = clock2alarm(new_timer->it_clock);
534         base = &alarm_bases[type];
535         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
536         return 0;
537 }
538 
539 /**
540  * alarm_timer_get - posix timer_get interface
541  * @new_timer: k_itimer pointer
542  * @cur_setting: itimerspec data to fill
543  *
544  * Copies the itimerspec data out from the k_itimer
545  */
546 static void alarm_timer_get(struct k_itimer *timr,
547                                 struct itimerspec *cur_setting)
548 {
549         memset(cur_setting, 0, sizeof(struct itimerspec));
550 
551         cur_setting->it_interval =
552                         ktime_to_timespec(timr->it.alarm.interval);
553         cur_setting->it_value =
554                 ktime_to_timespec(timr->it.alarm.alarmtimer.node.expires);
555         return;
556 }
557 
558 /**
559  * alarm_timer_del - posix timer_del interface
560  * @timr: k_itimer pointer to be deleted
561  *
562  * Cancels any programmed alarms for the given timer.
563  */
564 static int alarm_timer_del(struct k_itimer *timr)
565 {
566         if (!rtcdev)
567                 return -ENOTSUPP;
568 
569         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
570                 return TIMER_RETRY;
571 
572         return 0;
573 }
574 
575 /**
576  * alarm_timer_set - posix timer_set interface
577  * @timr: k_itimer pointer to be deleted
578  * @flags: timer flags
579  * @new_setting: itimerspec to be used
580  * @old_setting: itimerspec being replaced
581  *
582  * Sets the timer to new_setting, and starts the timer.
583  */
584 static int alarm_timer_set(struct k_itimer *timr, int flags,
585                                 struct itimerspec *new_setting,
586                                 struct itimerspec *old_setting)
587 {
588         if (!rtcdev)
589                 return -ENOTSUPP;
590 
591         if (old_setting)
592                 alarm_timer_get(timr, old_setting);
593 
594         /* If the timer was already set, cancel it */
595         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
596                 return TIMER_RETRY;
597 
598         /* start the timer */
599         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
600         alarm_start(&timr->it.alarm.alarmtimer,
601                         timespec_to_ktime(new_setting->it_value));
602         return 0;
603 }
604 
605 /**
606  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
607  * @alarm: ptr to alarm that fired
608  *
609  * Wakes up the task that set the alarmtimer
610  */
611 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
612                                                                 ktime_t now)
613 {
614         struct task_struct *task = (struct task_struct *)alarm->data;
615 
616         alarm->data = NULL;
617         if (task)
618                 wake_up_process(task);
619         return ALARMTIMER_NORESTART;
620 }
621 
622 /**
623  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
624  * @alarm: ptr to alarmtimer
625  * @absexp: absolute expiration time
626  *
627  * Sets the alarm timer and sleeps until it is fired or interrupted.
628  */
629 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
630 {
631         alarm->data = (void *)current;
632         do {
633                 set_current_state(TASK_INTERRUPTIBLE);
634                 alarm_start(alarm, absexp);
635                 if (likely(alarm->data))
636                         schedule();
637 
638                 alarm_cancel(alarm);
639         } while (alarm->data && !signal_pending(current));
640 
641         __set_current_state(TASK_RUNNING);
642 
643         return (alarm->data == NULL);
644 }
645 
646 
647 /**
648  * update_rmtp - Update remaining timespec value
649  * @exp: expiration time
650  * @type: timer type
651  * @rmtp: user pointer to remaining timepsec value
652  *
653  * Helper function that fills in rmtp value with time between
654  * now and the exp value
655  */
656 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
657                         struct timespec __user *rmtp)
658 {
659         struct timespec rmt;
660         ktime_t rem;
661 
662         rem = ktime_sub(exp, alarm_bases[type].gettime());
663 
664         if (rem.tv64 <= 0)
665                 return 0;
666         rmt = ktime_to_timespec(rem);
667 
668         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
669                 return -EFAULT;
670 
671         return 1;
672 
673 }
674 
675 /**
676  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
677  * @restart: ptr to restart block
678  *
679  * Handles restarted clock_nanosleep calls
680  */
681 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
682 {
683         enum  alarmtimer_type type = restart->nanosleep.clockid;
684         ktime_t exp;
685         struct timespec __user  *rmtp;
686         struct alarm alarm;
687         int ret = 0;
688 
689         exp.tv64 = restart->nanosleep.expires;
690         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
691 
692         if (alarmtimer_do_nsleep(&alarm, exp))
693                 goto out;
694 
695         if (freezing(current))
696                 alarmtimer_freezerset(exp, type);
697 
698         rmtp = restart->nanosleep.rmtp;
699         if (rmtp) {
700                 ret = update_rmtp(exp, type, rmtp);
701                 if (ret <= 0)
702                         goto out;
703         }
704 
705 
706         /* The other values in restart are already filled in */
707         ret = -ERESTART_RESTARTBLOCK;
708 out:
709         return ret;
710 }
711 
712 /**
713  * alarm_timer_nsleep - alarmtimer nanosleep
714  * @which_clock: clockid
715  * @flags: determins abstime or relative
716  * @tsreq: requested sleep time (abs or rel)
717  * @rmtp: remaining sleep time saved
718  *
719  * Handles clock_nanosleep calls against _ALARM clockids
720  */
721 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
722                      struct timespec *tsreq, struct timespec __user *rmtp)
723 {
724         enum  alarmtimer_type type = clock2alarm(which_clock);
725         struct alarm alarm;
726         ktime_t exp;
727         int ret = 0;
728         struct restart_block *restart;
729 
730         if (!alarmtimer_get_rtcdev())
731                 return -ENOTSUPP;
732 
733         if (!capable(CAP_WAKE_ALARM))
734                 return -EPERM;
735 
736         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
737 
738         exp = timespec_to_ktime(*tsreq);
739         /* Convert (if necessary) to absolute time */
740         if (flags != TIMER_ABSTIME) {
741                 ktime_t now = alarm_bases[type].gettime();
742                 exp = ktime_add(now, exp);
743         }
744 
745         if (alarmtimer_do_nsleep(&alarm, exp))
746                 goto out;
747 
748         if (freezing(current))
749                 alarmtimer_freezerset(exp, type);
750 
751         /* abs timers don't set remaining time or restart */
752         if (flags == TIMER_ABSTIME) {
753                 ret = -ERESTARTNOHAND;
754                 goto out;
755         }
756 
757         if (rmtp) {
758                 ret = update_rmtp(exp, type, rmtp);
759                 if (ret <= 0)
760                         goto out;
761         }
762 
763         restart = &current_thread_info()->restart_block;
764         restart->fn = alarm_timer_nsleep_restart;
765         restart->nanosleep.clockid = type;
766         restart->nanosleep.expires = exp.tv64;
767         restart->nanosleep.rmtp = rmtp;
768         ret = -ERESTART_RESTARTBLOCK;
769 
770 out:
771         return ret;
772 }
773 
774 
775 /* Suspend hook structures */
776 static const struct dev_pm_ops alarmtimer_pm_ops = {
777         .suspend = alarmtimer_suspend,
778 };
779 
780 static struct platform_driver alarmtimer_driver = {
781         .driver = {
782                 .name = "alarmtimer",
783                 .pm = &alarmtimer_pm_ops,
784         }
785 };
786 
787 /**
788  * alarmtimer_init - Initialize alarm timer code
789  *
790  * This function initializes the alarm bases and registers
791  * the posix clock ids.
792  */
793 static int __init alarmtimer_init(void)
794 {
795         struct platform_device *pdev;
796         int error = 0;
797         int i;
798         struct k_clock alarm_clock = {
799                 .clock_getres   = alarm_clock_getres,
800                 .clock_get      = alarm_clock_get,
801                 .timer_create   = alarm_timer_create,
802                 .timer_set      = alarm_timer_set,
803                 .timer_del      = alarm_timer_del,
804                 .timer_get      = alarm_timer_get,
805                 .nsleep         = alarm_timer_nsleep,
806         };
807 
808         alarmtimer_rtc_timer_init();
809 
810         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
811         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
812 
813         /* Initialize alarm bases */
814         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
815         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
816         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
817         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
818         for (i = 0; i < ALARM_NUMTYPE; i++) {
819                 timerqueue_init_head(&alarm_bases[i].timerqueue);
820                 spin_lock_init(&alarm_bases[i].lock);
821         }
822 
823         error = alarmtimer_rtc_interface_setup();
824         if (error)
825                 return error;
826 
827         error = platform_driver_register(&alarmtimer_driver);
828         if (error)
829                 goto out_if;
830 
831         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
832         if (IS_ERR(pdev)) {
833                 error = PTR_ERR(pdev);
834                 goto out_drv;
835         }
836         ws = wakeup_source_register("alarmtimer");
837         return 0;
838 
839 out_drv:
840         platform_driver_unregister(&alarmtimer_driver);
841 out_if:
842         alarmtimer_rtc_interface_remove();
843         return error;
844 }
845 device_initcall(alarmtimer_init);
846 

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