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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 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
 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 
275 static int alarmtimer_resume(struct device *dev)
276 {
277         struct rtc_device *rtc;
278 
279         rtc = alarmtimer_get_rtcdev();
280         if (rtc)
281                 rtc_timer_cancel(rtc, &rtctimer);
282         return 0;
283 }
284 
285 #else
286 static int alarmtimer_suspend(struct device *dev)
287 {
288         return 0;
289 }
290 
291 static int alarmtimer_resume(struct device *dev)
292 {
293         return 0;
294 }
295 #endif
296 
297 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
298 {
299         ktime_t delta;
300         unsigned long flags;
301         struct alarm_base *base = &alarm_bases[type];
302 
303         delta = ktime_sub(absexp, base->gettime());
304 
305         spin_lock_irqsave(&freezer_delta_lock, flags);
306         if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
307                 freezer_delta = delta;
308         spin_unlock_irqrestore(&freezer_delta_lock, flags);
309 }
310 
311 
312 /**
313  * alarm_init - Initialize an alarm structure
314  * @alarm: ptr to alarm to be initialized
315  * @type: the type of the alarm
316  * @function: callback that is run when the alarm fires
317  */
318 void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
319                 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
320 {
321         timerqueue_init(&alarm->node);
322         hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
323                         HRTIMER_MODE_ABS);
324         alarm->timer.function = alarmtimer_fired;
325         alarm->function = function;
326         alarm->type = type;
327         alarm->state = ALARMTIMER_STATE_INACTIVE;
328 }
329 EXPORT_SYMBOL_GPL(alarm_init);
330 
331 /**
332  * alarm_start - Sets an absolute alarm to fire
333  * @alarm: ptr to alarm to set
334  * @start: time to run the alarm
335  */
336 void alarm_start(struct alarm *alarm, ktime_t start)
337 {
338         struct alarm_base *base = &alarm_bases[alarm->type];
339         unsigned long flags;
340 
341         spin_lock_irqsave(&base->lock, flags);
342         alarm->node.expires = start;
343         alarmtimer_enqueue(base, alarm);
344         hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
345         spin_unlock_irqrestore(&base->lock, flags);
346 }
347 EXPORT_SYMBOL_GPL(alarm_start);
348 
349 /**
350  * alarm_start_relative - Sets a relative alarm to fire
351  * @alarm: ptr to alarm to set
352  * @start: time relative to now to run the alarm
353  */
354 void alarm_start_relative(struct alarm *alarm, ktime_t start)
355 {
356         struct alarm_base *base = &alarm_bases[alarm->type];
357 
358         start = ktime_add(start, base->gettime());
359         alarm_start(alarm, start);
360 }
361 EXPORT_SYMBOL_GPL(alarm_start_relative);
362 
363 void alarm_restart(struct alarm *alarm)
364 {
365         struct alarm_base *base = &alarm_bases[alarm->type];
366         unsigned long flags;
367 
368         spin_lock_irqsave(&base->lock, flags);
369         hrtimer_set_expires(&alarm->timer, alarm->node.expires);
370         hrtimer_restart(&alarm->timer);
371         alarmtimer_enqueue(base, alarm);
372         spin_unlock_irqrestore(&base->lock, flags);
373 }
374 EXPORT_SYMBOL_GPL(alarm_restart);
375 
376 /**
377  * alarm_try_to_cancel - Tries to cancel an alarm timer
378  * @alarm: ptr to alarm to be canceled
379  *
380  * Returns 1 if the timer was canceled, 0 if it was not running,
381  * and -1 if the callback was running
382  */
383 int alarm_try_to_cancel(struct alarm *alarm)
384 {
385         struct alarm_base *base = &alarm_bases[alarm->type];
386         unsigned long flags;
387         int ret;
388 
389         spin_lock_irqsave(&base->lock, flags);
390         ret = hrtimer_try_to_cancel(&alarm->timer);
391         if (ret >= 0)
392                 alarmtimer_dequeue(base, alarm);
393         spin_unlock_irqrestore(&base->lock, flags);
394         return ret;
395 }
396 EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
397 
398 
399 /**
400  * alarm_cancel - Spins trying to cancel an alarm timer until it is done
401  * @alarm: ptr to alarm to be canceled
402  *
403  * Returns 1 if the timer was canceled, 0 if it was not active.
404  */
405 int alarm_cancel(struct alarm *alarm)
406 {
407         for (;;) {
408                 int ret = alarm_try_to_cancel(alarm);
409                 if (ret >= 0)
410                         return ret;
411                 cpu_relax();
412         }
413 }
414 EXPORT_SYMBOL_GPL(alarm_cancel);
415 
416 
417 u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
418 {
419         u64 overrun = 1;
420         ktime_t delta;
421 
422         delta = ktime_sub(now, alarm->node.expires);
423 
424         if (delta.tv64 < 0)
425                 return 0;
426 
427         if (unlikely(delta.tv64 >= interval.tv64)) {
428                 s64 incr = ktime_to_ns(interval);
429 
430                 overrun = ktime_divns(delta, incr);
431 
432                 alarm->node.expires = ktime_add_ns(alarm->node.expires,
433                                                         incr*overrun);
434 
435                 if (alarm->node.expires.tv64 > now.tv64)
436                         return overrun;
437                 /*
438                  * This (and the ktime_add() below) is the
439                  * correction for exact:
440                  */
441                 overrun++;
442         }
443 
444         alarm->node.expires = ktime_add(alarm->node.expires, interval);
445         return overrun;
446 }
447 EXPORT_SYMBOL_GPL(alarm_forward);
448 
449 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
450 {
451         struct alarm_base *base = &alarm_bases[alarm->type];
452 
453         return alarm_forward(alarm, base->gettime(), interval);
454 }
455 EXPORT_SYMBOL_GPL(alarm_forward_now);
456 
457 
458 /**
459  * clock2alarm - helper that converts from clockid to alarmtypes
460  * @clockid: clockid.
461  */
462 static enum alarmtimer_type clock2alarm(clockid_t clockid)
463 {
464         if (clockid == CLOCK_REALTIME_ALARM)
465                 return ALARM_REALTIME;
466         if (clockid == CLOCK_BOOTTIME_ALARM)
467                 return ALARM_BOOTTIME;
468         return -1;
469 }
470 
471 /**
472  * alarm_handle_timer - Callback for posix timers
473  * @alarm: alarm that fired
474  *
475  * Posix timer callback for expired alarm timers.
476  */
477 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
478                                                         ktime_t now)
479 {
480         unsigned long flags;
481         struct k_itimer *ptr = container_of(alarm, struct k_itimer,
482                                                 it.alarm.alarmtimer);
483         enum alarmtimer_restart result = ALARMTIMER_NORESTART;
484 
485         spin_lock_irqsave(&ptr->it_lock, flags);
486         if ((ptr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) {
487                 if (posix_timer_event(ptr, 0) != 0)
488                         ptr->it_overrun++;
489         }
490 
491         /* Re-add periodic timers */
492         if (ptr->it.alarm.interval.tv64) {
493                 ptr->it_overrun += alarm_forward(alarm, now,
494                                                 ptr->it.alarm.interval);
495                 result = ALARMTIMER_RESTART;
496         }
497         spin_unlock_irqrestore(&ptr->it_lock, flags);
498 
499         return result;
500 }
501 
502 /**
503  * alarm_clock_getres - posix getres interface
504  * @which_clock: clockid
505  * @tp: timespec to fill
506  *
507  * Returns the granularity of underlying alarm base clock
508  */
509 static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
510 {
511         if (!alarmtimer_get_rtcdev())
512                 return -EINVAL;
513 
514         tp->tv_sec = 0;
515         tp->tv_nsec = hrtimer_resolution;
516         return 0;
517 }
518 
519 /**
520  * alarm_clock_get - posix clock_get interface
521  * @which_clock: clockid
522  * @tp: timespec to fill.
523  *
524  * Provides the underlying alarm base time.
525  */
526 static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
527 {
528         struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
529 
530         if (!alarmtimer_get_rtcdev())
531                 return -EINVAL;
532 
533         *tp = ktime_to_timespec(base->gettime());
534         return 0;
535 }
536 
537 /**
538  * alarm_timer_create - posix timer_create interface
539  * @new_timer: k_itimer pointer to manage
540  *
541  * Initializes the k_itimer structure.
542  */
543 static int alarm_timer_create(struct k_itimer *new_timer)
544 {
545         enum  alarmtimer_type type;
546         struct alarm_base *base;
547 
548         if (!alarmtimer_get_rtcdev())
549                 return -ENOTSUPP;
550 
551         if (!capable(CAP_WAKE_ALARM))
552                 return -EPERM;
553 
554         type = clock2alarm(new_timer->it_clock);
555         base = &alarm_bases[type];
556         alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
557         return 0;
558 }
559 
560 /**
561  * alarm_timer_get - posix timer_get interface
562  * @new_timer: k_itimer pointer
563  * @cur_setting: itimerspec data to fill
564  *
565  * Copies out the current itimerspec data
566  */
567 static void alarm_timer_get(struct k_itimer *timr,
568                                 struct itimerspec *cur_setting)
569 {
570         ktime_t relative_expiry_time =
571                 alarm_expires_remaining(&(timr->it.alarm.alarmtimer));
572 
573         if (ktime_to_ns(relative_expiry_time) > 0) {
574                 cur_setting->it_value = ktime_to_timespec(relative_expiry_time);
575         } else {
576                 cur_setting->it_value.tv_sec = 0;
577                 cur_setting->it_value.tv_nsec = 0;
578         }
579 
580         cur_setting->it_interval = ktime_to_timespec(timr->it.alarm.interval);
581 }
582 
583 /**
584  * alarm_timer_del - posix timer_del interface
585  * @timr: k_itimer pointer to be deleted
586  *
587  * Cancels any programmed alarms for the given timer.
588  */
589 static int alarm_timer_del(struct k_itimer *timr)
590 {
591         if (!rtcdev)
592                 return -ENOTSUPP;
593 
594         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
595                 return TIMER_RETRY;
596 
597         return 0;
598 }
599 
600 /**
601  * alarm_timer_set - posix timer_set interface
602  * @timr: k_itimer pointer to be deleted
603  * @flags: timer flags
604  * @new_setting: itimerspec to be used
605  * @old_setting: itimerspec being replaced
606  *
607  * Sets the timer to new_setting, and starts the timer.
608  */
609 static int alarm_timer_set(struct k_itimer *timr, int flags,
610                                 struct itimerspec *new_setting,
611                                 struct itimerspec *old_setting)
612 {
613         ktime_t exp;
614 
615         if (!rtcdev)
616                 return -ENOTSUPP;
617 
618         if (flags & ~TIMER_ABSTIME)
619                 return -EINVAL;
620 
621         if (old_setting)
622                 alarm_timer_get(timr, old_setting);
623 
624         /* If the timer was already set, cancel it */
625         if (alarm_try_to_cancel(&timr->it.alarm.alarmtimer) < 0)
626                 return TIMER_RETRY;
627 
628         /* start the timer */
629         timr->it.alarm.interval = timespec_to_ktime(new_setting->it_interval);
630         exp = timespec_to_ktime(new_setting->it_value);
631         /* Convert (if necessary) to absolute time */
632         if (flags != TIMER_ABSTIME) {
633                 ktime_t now;
634 
635                 now = alarm_bases[timr->it.alarm.alarmtimer.type].gettime();
636                 exp = ktime_add(now, exp);
637         }
638 
639         alarm_start(&timr->it.alarm.alarmtimer, exp);
640         return 0;
641 }
642 
643 /**
644  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
645  * @alarm: ptr to alarm that fired
646  *
647  * Wakes up the task that set the alarmtimer
648  */
649 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
650                                                                 ktime_t now)
651 {
652         struct task_struct *task = (struct task_struct *)alarm->data;
653 
654         alarm->data = NULL;
655         if (task)
656                 wake_up_process(task);
657         return ALARMTIMER_NORESTART;
658 }
659 
660 /**
661  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
662  * @alarm: ptr to alarmtimer
663  * @absexp: absolute expiration time
664  *
665  * Sets the alarm timer and sleeps until it is fired or interrupted.
666  */
667 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
668 {
669         alarm->data = (void *)current;
670         do {
671                 set_current_state(TASK_INTERRUPTIBLE);
672                 alarm_start(alarm, absexp);
673                 if (likely(alarm->data))
674                         schedule();
675 
676                 alarm_cancel(alarm);
677         } while (alarm->data && !signal_pending(current));
678 
679         __set_current_state(TASK_RUNNING);
680 
681         return (alarm->data == NULL);
682 }
683 
684 
685 /**
686  * update_rmtp - Update remaining timespec value
687  * @exp: expiration time
688  * @type: timer type
689  * @rmtp: user pointer to remaining timepsec value
690  *
691  * Helper function that fills in rmtp value with time between
692  * now and the exp value
693  */
694 static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
695                         struct timespec __user *rmtp)
696 {
697         struct timespec rmt;
698         ktime_t rem;
699 
700         rem = ktime_sub(exp, alarm_bases[type].gettime());
701 
702         if (rem.tv64 <= 0)
703                 return 0;
704         rmt = ktime_to_timespec(rem);
705 
706         if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
707                 return -EFAULT;
708 
709         return 1;
710 
711 }
712 
713 /**
714  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
715  * @restart: ptr to restart block
716  *
717  * Handles restarted clock_nanosleep calls
718  */
719 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
720 {
721         enum  alarmtimer_type type = restart->nanosleep.clockid;
722         ktime_t exp;
723         struct timespec __user  *rmtp;
724         struct alarm alarm;
725         int ret = 0;
726 
727         exp.tv64 = restart->nanosleep.expires;
728         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
729 
730         if (alarmtimer_do_nsleep(&alarm, exp))
731                 goto out;
732 
733         if (freezing(current))
734                 alarmtimer_freezerset(exp, type);
735 
736         rmtp = restart->nanosleep.rmtp;
737         if (rmtp) {
738                 ret = update_rmtp(exp, type, rmtp);
739                 if (ret <= 0)
740                         goto out;
741         }
742 
743 
744         /* The other values in restart are already filled in */
745         ret = -ERESTART_RESTARTBLOCK;
746 out:
747         return ret;
748 }
749 
750 /**
751  * alarm_timer_nsleep - alarmtimer nanosleep
752  * @which_clock: clockid
753  * @flags: determins abstime or relative
754  * @tsreq: requested sleep time (abs or rel)
755  * @rmtp: remaining sleep time saved
756  *
757  * Handles clock_nanosleep calls against _ALARM clockids
758  */
759 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
760                      struct timespec *tsreq, struct timespec __user *rmtp)
761 {
762         enum  alarmtimer_type type = clock2alarm(which_clock);
763         struct alarm alarm;
764         ktime_t exp;
765         int ret = 0;
766         struct restart_block *restart;
767 
768         if (!alarmtimer_get_rtcdev())
769                 return -ENOTSUPP;
770 
771         if (flags & ~TIMER_ABSTIME)
772                 return -EINVAL;
773 
774         if (!capable(CAP_WAKE_ALARM))
775                 return -EPERM;
776 
777         alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
778 
779         exp = timespec_to_ktime(*tsreq);
780         /* Convert (if necessary) to absolute time */
781         if (flags != TIMER_ABSTIME) {
782                 ktime_t now = alarm_bases[type].gettime();
783                 exp = ktime_add(now, exp);
784         }
785 
786         if (alarmtimer_do_nsleep(&alarm, exp))
787                 goto out;
788 
789         if (freezing(current))
790                 alarmtimer_freezerset(exp, type);
791 
792         /* abs timers don't set remaining time or restart */
793         if (flags == TIMER_ABSTIME) {
794                 ret = -ERESTARTNOHAND;
795                 goto out;
796         }
797 
798         if (rmtp) {
799                 ret = update_rmtp(exp, type, rmtp);
800                 if (ret <= 0)
801                         goto out;
802         }
803 
804         restart = &current->restart_block;
805         restart->fn = alarm_timer_nsleep_restart;
806         restart->nanosleep.clockid = type;
807         restart->nanosleep.expires = exp.tv64;
808         restart->nanosleep.rmtp = rmtp;
809         ret = -ERESTART_RESTARTBLOCK;
810 
811 out:
812         return ret;
813 }
814 
815 
816 /* Suspend hook structures */
817 static const struct dev_pm_ops alarmtimer_pm_ops = {
818         .suspend = alarmtimer_suspend,
819         .resume = alarmtimer_resume,
820 };
821 
822 static struct platform_driver alarmtimer_driver = {
823         .driver = {
824                 .name = "alarmtimer",
825                 .pm = &alarmtimer_pm_ops,
826         }
827 };
828 
829 /**
830  * alarmtimer_init - Initialize alarm timer code
831  *
832  * This function initializes the alarm bases and registers
833  * the posix clock ids.
834  */
835 static int __init alarmtimer_init(void)
836 {
837         struct platform_device *pdev;
838         int error = 0;
839         int i;
840         struct k_clock alarm_clock = {
841                 .clock_getres   = alarm_clock_getres,
842                 .clock_get      = alarm_clock_get,
843                 .timer_create   = alarm_timer_create,
844                 .timer_set      = alarm_timer_set,
845                 .timer_del      = alarm_timer_del,
846                 .timer_get      = alarm_timer_get,
847                 .nsleep         = alarm_timer_nsleep,
848         };
849 
850         alarmtimer_rtc_timer_init();
851 
852         posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
853         posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
854 
855         /* Initialize alarm bases */
856         alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
857         alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
858         alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
859         alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
860         for (i = 0; i < ALARM_NUMTYPE; i++) {
861                 timerqueue_init_head(&alarm_bases[i].timerqueue);
862                 spin_lock_init(&alarm_bases[i].lock);
863         }
864 
865         error = alarmtimer_rtc_interface_setup();
866         if (error)
867                 return error;
868 
869         error = platform_driver_register(&alarmtimer_driver);
870         if (error)
871                 goto out_if;
872 
873         pdev = platform_device_register_simple("alarmtimer", -1, NULL, 0);
874         if (IS_ERR(pdev)) {
875                 error = PTR_ERR(pdev);
876                 goto out_drv;
877         }
878         ws = wakeup_source_register("alarmtimer");
879         return 0;
880 
881 out_drv:
882         platform_driver_unregister(&alarmtimer_driver);
883 out_if:
884         alarmtimer_rtc_interface_remove();
885         return error;
886 }
887 device_initcall(alarmtimer_init);
888 

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