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Linux/kernel/time/alarmtimer.c

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

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