Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Alarmtimer interface
4 *
5 * This interface provides a timer which is similar to hrtimers,
6 * but triggers a RTC alarm if the box is suspend.
7 *
8 * This interface is influenced by the Android RTC Alarm timer
9 * interface.
10 *
11 * Copyright (C) 2010 IBM Corporation
12 *
13 * Author: John Stultz <john.stultz@linaro.org>
14 */
15#include <linux/time.h>
16#include <linux/hrtimer.h>
17#include <linux/timerqueue.h>
18#include <linux/rtc.h>
19#include <linux/sched/signal.h>
20#include <linux/sched/debug.h>
21#include <linux/alarmtimer.h>
22#include <linux/mutex.h>
23#include <linux/platform_device.h>
24#include <linux/posix-timers.h>
25#include <linux/workqueue.h>
26#include <linux/freezer.h>
27#include <linux/compat.h>
28#include <linux/module.h>
29#include <linux/time_namespace.h>
30
31#include "posix-timers.h"
32
33#define CREATE_TRACE_POINTS
34#include <trace/events/alarmtimer.h>
35
36/**
37 * struct alarm_base - Alarm timer bases
38 * @lock: Lock for syncrhonized access to the base
39 * @timerqueue: Timerqueue head managing the list of events
40 * @get_ktime: Function to read the time correlating to the base
41 * @get_timespec: Function to read the namespace time correlating to the base
42 * @base_clockid: clockid for the base
43 */
44static struct alarm_base {
45 spinlock_t lock;
46 struct timerqueue_head timerqueue;
47 ktime_t (*get_ktime)(void);
48 void (*get_timespec)(struct timespec64 *tp);
49 clockid_t base_clockid;
50} alarm_bases[ALARM_NUMTYPE];
51
52#if defined(CONFIG_POSIX_TIMERS) || defined(CONFIG_RTC_CLASS)
53/* freezer information to handle clock_nanosleep triggered wakeups */
54static enum alarmtimer_type freezer_alarmtype;
55static ktime_t freezer_expires;
56static ktime_t freezer_delta;
57static DEFINE_SPINLOCK(freezer_delta_lock);
58#endif
59
60#ifdef CONFIG_RTC_CLASS
61/* rtc timer and device for setting alarm wakeups at suspend */
62static struct rtc_timer rtctimer;
63static struct rtc_device *rtcdev;
64static DEFINE_SPINLOCK(rtcdev_lock);
65
66/**
67 * alarmtimer_get_rtcdev - Return selected rtcdevice
68 *
69 * This function returns the rtc device to use for wakealarms.
70 */
71struct rtc_device *alarmtimer_get_rtcdev(void)
72{
73 unsigned long flags;
74 struct rtc_device *ret;
75
76 spin_lock_irqsave(&rtcdev_lock, flags);
77 ret = rtcdev;
78 spin_unlock_irqrestore(&rtcdev_lock, flags);
79
80 return ret;
81}
82EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
83
84static int alarmtimer_rtc_add_device(struct device *dev,
85 struct class_interface *class_intf)
86{
87 unsigned long flags;
88 struct rtc_device *rtc = to_rtc_device(dev);
89 struct platform_device *pdev;
90 int ret = 0;
91
92 if (rtcdev)
93 return -EBUSY;
94
95 if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
96 return -1;
97 if (!device_may_wakeup(rtc->dev.parent))
98 return -1;
99
100 pdev = platform_device_register_data(dev, "alarmtimer",
101 PLATFORM_DEVID_AUTO, NULL, 0);
102 if (!IS_ERR(pdev))
103 device_init_wakeup(&pdev->dev, true);
104
105 spin_lock_irqsave(&rtcdev_lock, flags);
106 if (!IS_ERR(pdev) && !rtcdev) {
107 if (!try_module_get(rtc->owner)) {
108 ret = -1;
109 goto unlock;
110 }
111
112 rtcdev = rtc;
113 /* hold a reference so it doesn't go away */
114 get_device(dev);
115 pdev = NULL;
116 } else {
117 ret = -1;
118 }
119unlock:
120 spin_unlock_irqrestore(&rtcdev_lock, flags);
121
122 platform_device_unregister(pdev);
123
124 return ret;
125}
126
127static inline void alarmtimer_rtc_timer_init(void)
128{
129 rtc_timer_init(&rtctimer, NULL, NULL);
130}
131
132static struct class_interface alarmtimer_rtc_interface = {
133 .add_dev = &alarmtimer_rtc_add_device,
134};
135
136static int alarmtimer_rtc_interface_setup(void)
137{
138 alarmtimer_rtc_interface.class = rtc_class;
139 return class_interface_register(&alarmtimer_rtc_interface);
140}
141static void alarmtimer_rtc_interface_remove(void)
142{
143 class_interface_unregister(&alarmtimer_rtc_interface);
144}
145#else
146static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
147static inline void alarmtimer_rtc_interface_remove(void) { }
148static inline void alarmtimer_rtc_timer_init(void) { }
149#endif
150
151/**
152 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
153 * @base: pointer to the base where the timer is being run
154 * @alarm: pointer to alarm being enqueued.
155 *
156 * Adds alarm to a alarm_base timerqueue
157 *
158 * Must hold base->lock when calling.
159 */
160static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
161{
162 if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
163 timerqueue_del(&base->timerqueue, &alarm->node);
164
165 timerqueue_add(&base->timerqueue, &alarm->node);
166 alarm->state |= ALARMTIMER_STATE_ENQUEUED;
167}
168
169/**
170 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
171 * @base: pointer to the base where the timer is running
172 * @alarm: pointer to alarm being removed
173 *
174 * Removes alarm to a alarm_base timerqueue
175 *
176 * Must hold base->lock when calling.
177 */
178static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
179{
180 if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
181 return;
182
183 timerqueue_del(&base->timerqueue, &alarm->node);
184 alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
185}
186
187
188/**
189 * alarmtimer_fired - Handles alarm hrtimer being fired.
190 * @timer: pointer to hrtimer being run
191 *
192 * When a alarm timer fires, this runs through the timerqueue to
193 * see which alarms expired, and runs those. If there are more alarm
194 * timers queued for the future, we set the hrtimer to fire when
195 * the next future alarm timer expires.
196 */
197static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
198{
199 struct alarm *alarm = container_of(timer, struct alarm, timer);
200 struct alarm_base *base = &alarm_bases[alarm->type];
201 unsigned long flags;
202 int ret = HRTIMER_NORESTART;
203 int restart = ALARMTIMER_NORESTART;
204
205 spin_lock_irqsave(&base->lock, flags);
206 alarmtimer_dequeue(base, alarm);
207 spin_unlock_irqrestore(&base->lock, flags);
208
209 if (alarm->function)
210 restart = alarm->function(alarm, base->get_ktime());
211
212 spin_lock_irqsave(&base->lock, flags);
213 if (restart != ALARMTIMER_NORESTART) {
214 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
215 alarmtimer_enqueue(base, alarm);
216 ret = HRTIMER_RESTART;
217 }
218 spin_unlock_irqrestore(&base->lock, flags);
219
220 trace_alarmtimer_fired(alarm, base->get_ktime());
221 return ret;
222
223}
224
225ktime_t alarm_expires_remaining(const struct alarm *alarm)
226{
227 struct alarm_base *base = &alarm_bases[alarm->type];
228 return ktime_sub(alarm->node.expires, base->get_ktime());
229}
230EXPORT_SYMBOL_GPL(alarm_expires_remaining);
231
232#ifdef CONFIG_RTC_CLASS
233/**
234 * alarmtimer_suspend - Suspend time callback
235 * @dev: unused
236 *
237 * When we are going into suspend, we look through the bases
238 * to see which is the soonest timer to expire. We then
239 * set an rtc timer to fire that far into the future, which
240 * will wake us from suspend.
241 */
242static int alarmtimer_suspend(struct device *dev)
243{
244 ktime_t min, now, expires;
245 int i, ret, type;
246 struct rtc_device *rtc;
247 unsigned long flags;
248 struct rtc_time tm;
249
250 spin_lock_irqsave(&freezer_delta_lock, flags);
251 min = freezer_delta;
252 expires = freezer_expires;
253 type = freezer_alarmtype;
254 freezer_delta = 0;
255 spin_unlock_irqrestore(&freezer_delta_lock, flags);
256
257 rtc = alarmtimer_get_rtcdev();
258 /* If we have no rtcdev, just return */
259 if (!rtc)
260 return 0;
261
262 /* Find the soonest timer to expire*/
263 for (i = 0; i < ALARM_NUMTYPE; i++) {
264 struct alarm_base *base = &alarm_bases[i];
265 struct timerqueue_node *next;
266 ktime_t delta;
267
268 spin_lock_irqsave(&base->lock, flags);
269 next = timerqueue_getnext(&base->timerqueue);
270 spin_unlock_irqrestore(&base->lock, flags);
271 if (!next)
272 continue;
273 delta = ktime_sub(next->expires, base->get_ktime());
274 if (!min || (delta < min)) {
275 expires = next->expires;
276 min = delta;
277 type = i;
278 }
279 }
280 if (min == 0)
281 return 0;
282
283 if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
284 pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
285 return -EBUSY;
286 }
287
288 trace_alarmtimer_suspend(expires, type);
289
290 /* Setup an rtc timer to fire that far in the future */
291 rtc_timer_cancel(rtc, &rtctimer);
292 rtc_read_time(rtc, &tm);
293 now = rtc_tm_to_ktime(tm);
294 now = ktime_add(now, min);
295
296 /* Set alarm, if in the past reject suspend briefly to handle */
297 ret = rtc_timer_start(rtc, &rtctimer, now, 0);
298 if (ret < 0)
299 pm_wakeup_event(dev, MSEC_PER_SEC);
300 return ret;
301}
302
303static int alarmtimer_resume(struct device *dev)
304{
305 struct rtc_device *rtc;
306
307 rtc = alarmtimer_get_rtcdev();
308 if (rtc)
309 rtc_timer_cancel(rtc, &rtctimer);
310 return 0;
311}
312
313#else
314static int alarmtimer_suspend(struct device *dev)
315{
316 return 0;
317}
318
319static int alarmtimer_resume(struct device *dev)
320{
321 return 0;
322}
323#endif
324
325static void
326__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
327 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
328{
329 timerqueue_init(&alarm->node);
330 alarm->timer.function = alarmtimer_fired;
331 alarm->function = function;
332 alarm->type = type;
333 alarm->state = ALARMTIMER_STATE_INACTIVE;
334}
335
336/**
337 * alarm_init - Initialize an alarm structure
338 * @alarm: ptr to alarm to be initialized
339 * @type: the type of the alarm
340 * @function: callback that is run when the alarm fires
341 */
342void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
343 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
344{
345 hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
346 HRTIMER_MODE_ABS);
347 __alarm_init(alarm, type, function);
348}
349EXPORT_SYMBOL_GPL(alarm_init);
350
351/**
352 * alarm_start - Sets an absolute alarm to fire
353 * @alarm: ptr to alarm to set
354 * @start: time to run the alarm
355 */
356void alarm_start(struct alarm *alarm, ktime_t start)
357{
358 struct alarm_base *base = &alarm_bases[alarm->type];
359 unsigned long flags;
360
361 spin_lock_irqsave(&base->lock, flags);
362 alarm->node.expires = start;
363 alarmtimer_enqueue(base, alarm);
364 hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
365 spin_unlock_irqrestore(&base->lock, flags);
366
367 trace_alarmtimer_start(alarm, base->get_ktime());
368}
369EXPORT_SYMBOL_GPL(alarm_start);
370
371/**
372 * alarm_start_relative - Sets a relative alarm to fire
373 * @alarm: ptr to alarm to set
374 * @start: time relative to now to run the alarm
375 */
376void alarm_start_relative(struct alarm *alarm, ktime_t start)
377{
378 struct alarm_base *base = &alarm_bases[alarm->type];
379
380 start = ktime_add_safe(start, base->get_ktime());
381 alarm_start(alarm, start);
382}
383EXPORT_SYMBOL_GPL(alarm_start_relative);
384
385void alarm_restart(struct alarm *alarm)
386{
387 struct alarm_base *base = &alarm_bases[alarm->type];
388 unsigned long flags;
389
390 spin_lock_irqsave(&base->lock, flags);
391 hrtimer_set_expires(&alarm->timer, alarm->node.expires);
392 hrtimer_restart(&alarm->timer);
393 alarmtimer_enqueue(base, alarm);
394 spin_unlock_irqrestore(&base->lock, flags);
395}
396EXPORT_SYMBOL_GPL(alarm_restart);
397
398/**
399 * alarm_try_to_cancel - Tries to cancel an alarm timer
400 * @alarm: ptr to alarm to be canceled
401 *
402 * Returns 1 if the timer was canceled, 0 if it was not running,
403 * and -1 if the callback was running
404 */
405int alarm_try_to_cancel(struct alarm *alarm)
406{
407 struct alarm_base *base = &alarm_bases[alarm->type];
408 unsigned long flags;
409 int ret;
410
411 spin_lock_irqsave(&base->lock, flags);
412 ret = hrtimer_try_to_cancel(&alarm->timer);
413 if (ret >= 0)
414 alarmtimer_dequeue(base, alarm);
415 spin_unlock_irqrestore(&base->lock, flags);
416
417 trace_alarmtimer_cancel(alarm, base->get_ktime());
418 return ret;
419}
420EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
421
422
423/**
424 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
425 * @alarm: ptr to alarm to be canceled
426 *
427 * Returns 1 if the timer was canceled, 0 if it was not active.
428 */
429int alarm_cancel(struct alarm *alarm)
430{
431 for (;;) {
432 int ret = alarm_try_to_cancel(alarm);
433 if (ret >= 0)
434 return ret;
435 hrtimer_cancel_wait_running(&alarm->timer);
436 }
437}
438EXPORT_SYMBOL_GPL(alarm_cancel);
439
440
441u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
442{
443 u64 overrun = 1;
444 ktime_t delta;
445
446 delta = ktime_sub(now, alarm->node.expires);
447
448 if (delta < 0)
449 return 0;
450
451 if (unlikely(delta >= interval)) {
452 s64 incr = ktime_to_ns(interval);
453
454 overrun = ktime_divns(delta, incr);
455
456 alarm->node.expires = ktime_add_ns(alarm->node.expires,
457 incr*overrun);
458
459 if (alarm->node.expires > now)
460 return overrun;
461 /*
462 * This (and the ktime_add() below) is the
463 * correction for exact:
464 */
465 overrun++;
466 }
467
468 alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
469 return overrun;
470}
471EXPORT_SYMBOL_GPL(alarm_forward);
472
473static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
474{
475 struct alarm_base *base = &alarm_bases[alarm->type];
476 ktime_t now = base->get_ktime();
477
478 if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
479 /*
480 * Same issue as with posix_timer_fn(). Timers which are
481 * periodic but the signal is ignored can starve the system
482 * with a very small interval. The real fix which was
483 * promised in the context of posix_timer_fn() never
484 * materialized, but someone should really work on it.
485 *
486 * To prevent DOS fake @now to be 1 jiffie out which keeps
487 * the overrun accounting correct but creates an
488 * inconsistency vs. timer_gettime(2).
489 */
490 ktime_t kj = NSEC_PER_SEC / HZ;
491
492 if (interval < kj)
493 now = ktime_add(now, kj);
494 }
495
496 return alarm_forward(alarm, now, interval);
497}
498
499u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
500{
501 return __alarm_forward_now(alarm, interval, false);
502}
503EXPORT_SYMBOL_GPL(alarm_forward_now);
504
505#ifdef CONFIG_POSIX_TIMERS
506
507static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
508{
509 struct alarm_base *base;
510 unsigned long flags;
511 ktime_t delta;
512
513 switch(type) {
514 case ALARM_REALTIME:
515 base = &alarm_bases[ALARM_REALTIME];
516 type = ALARM_REALTIME_FREEZER;
517 break;
518 case ALARM_BOOTTIME:
519 base = &alarm_bases[ALARM_BOOTTIME];
520 type = ALARM_BOOTTIME_FREEZER;
521 break;
522 default:
523 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
524 return;
525 }
526
527 delta = ktime_sub(absexp, base->get_ktime());
528
529 spin_lock_irqsave(&freezer_delta_lock, flags);
530 if (!freezer_delta || (delta < freezer_delta)) {
531 freezer_delta = delta;
532 freezer_expires = absexp;
533 freezer_alarmtype = type;
534 }
535 spin_unlock_irqrestore(&freezer_delta_lock, flags);
536}
537
538/**
539 * clock2alarm - helper that converts from clockid to alarmtypes
540 * @clockid: clockid.
541 */
542static enum alarmtimer_type clock2alarm(clockid_t clockid)
543{
544 if (clockid == CLOCK_REALTIME_ALARM)
545 return ALARM_REALTIME;
546 if (clockid == CLOCK_BOOTTIME_ALARM)
547 return ALARM_BOOTTIME;
548 return -1;
549}
550
551/**
552 * alarm_handle_timer - Callback for posix timers
553 * @alarm: alarm that fired
554 * @now: time at the timer expiration
555 *
556 * Posix timer callback for expired alarm timers.
557 *
558 * Return: whether the timer is to be restarted
559 */
560static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
561 ktime_t now)
562{
563 struct k_itimer *ptr = container_of(alarm, struct k_itimer,
564 it.alarm.alarmtimer);
565 enum alarmtimer_restart result = ALARMTIMER_NORESTART;
566 unsigned long flags;
567 int si_private = 0;
568
569 spin_lock_irqsave(&ptr->it_lock, flags);
570
571 ptr->it_active = 0;
572 if (ptr->it_interval)
573 si_private = ++ptr->it_requeue_pending;
574
575 if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
576 /*
577 * Handle ignored signals and rearm the timer. This will go
578 * away once we handle ignored signals proper. Ensure that
579 * small intervals cannot starve the system.
580 */
581 ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
582 ++ptr->it_requeue_pending;
583 ptr->it_active = 1;
584 result = ALARMTIMER_RESTART;
585 }
586 spin_unlock_irqrestore(&ptr->it_lock, flags);
587
588 return result;
589}
590
591/**
592 * alarm_timer_rearm - Posix timer callback for rearming timer
593 * @timr: Pointer to the posixtimer data struct
594 */
595static void alarm_timer_rearm(struct k_itimer *timr)
596{
597 struct alarm *alarm = &timr->it.alarm.alarmtimer;
598
599 timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
600 alarm_start(alarm, alarm->node.expires);
601}
602
603/**
604 * alarm_timer_forward - Posix timer callback for forwarding timer
605 * @timr: Pointer to the posixtimer data struct
606 * @now: Current time to forward the timer against
607 */
608static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
609{
610 struct alarm *alarm = &timr->it.alarm.alarmtimer;
611
612 return alarm_forward(alarm, timr->it_interval, now);
613}
614
615/**
616 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
617 * @timr: Pointer to the posixtimer data struct
618 * @now: Current time to calculate against
619 */
620static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
621{
622 struct alarm *alarm = &timr->it.alarm.alarmtimer;
623
624 return ktime_sub(alarm->node.expires, now);
625}
626
627/**
628 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
629 * @timr: Pointer to the posixtimer data struct
630 */
631static int alarm_timer_try_to_cancel(struct k_itimer *timr)
632{
633 return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
634}
635
636/**
637 * alarm_timer_wait_running - Posix timer callback to wait for a timer
638 * @timr: Pointer to the posixtimer data struct
639 *
640 * Called from the core code when timer cancel detected that the callback
641 * is running. @timr is unlocked and rcu read lock is held to prevent it
642 * from being freed.
643 */
644static void alarm_timer_wait_running(struct k_itimer *timr)
645{
646 hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
647}
648
649/**
650 * alarm_timer_arm - Posix timer callback to arm a timer
651 * @timr: Pointer to the posixtimer data struct
652 * @expires: The new expiry time
653 * @absolute: Expiry value is absolute time
654 * @sigev_none: Posix timer does not deliver signals
655 */
656static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
657 bool absolute, bool sigev_none)
658{
659 struct alarm *alarm = &timr->it.alarm.alarmtimer;
660 struct alarm_base *base = &alarm_bases[alarm->type];
661
662 if (!absolute)
663 expires = ktime_add_safe(expires, base->get_ktime());
664 if (sigev_none)
665 alarm->node.expires = expires;
666 else
667 alarm_start(&timr->it.alarm.alarmtimer, expires);
668}
669
670/**
671 * alarm_clock_getres - posix getres interface
672 * @which_clock: clockid
673 * @tp: timespec to fill
674 *
675 * Returns the granularity of underlying alarm base clock
676 */
677static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
678{
679 if (!alarmtimer_get_rtcdev())
680 return -EINVAL;
681
682 tp->tv_sec = 0;
683 tp->tv_nsec = hrtimer_resolution;
684 return 0;
685}
686
687/**
688 * alarm_clock_get_timespec - posix clock_get_timespec interface
689 * @which_clock: clockid
690 * @tp: timespec to fill.
691 *
692 * Provides the underlying alarm base time in a tasks time namespace.
693 */
694static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
695{
696 struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
697
698 if (!alarmtimer_get_rtcdev())
699 return -EINVAL;
700
701 base->get_timespec(tp);
702
703 return 0;
704}
705
706/**
707 * alarm_clock_get_ktime - posix clock_get_ktime interface
708 * @which_clock: clockid
709 *
710 * Provides the underlying alarm base time in the root namespace.
711 */
712static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
713{
714 struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
715
716 if (!alarmtimer_get_rtcdev())
717 return -EINVAL;
718
719 return base->get_ktime();
720}
721
722/**
723 * alarm_timer_create - posix timer_create interface
724 * @new_timer: k_itimer pointer to manage
725 *
726 * Initializes the k_itimer structure.
727 */
728static int alarm_timer_create(struct k_itimer *new_timer)
729{
730 enum alarmtimer_type type;
731
732 if (!alarmtimer_get_rtcdev())
733 return -EOPNOTSUPP;
734
735 if (!capable(CAP_WAKE_ALARM))
736 return -EPERM;
737
738 type = clock2alarm(new_timer->it_clock);
739 alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
740 return 0;
741}
742
743/**
744 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
745 * @alarm: ptr to alarm that fired
746 * @now: time at the timer expiration
747 *
748 * Wakes up the task that set the alarmtimer
749 *
750 * Return: ALARMTIMER_NORESTART
751 */
752static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
753 ktime_t now)
754{
755 struct task_struct *task = (struct task_struct *)alarm->data;
756
757 alarm->data = NULL;
758 if (task)
759 wake_up_process(task);
760 return ALARMTIMER_NORESTART;
761}
762
763/**
764 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
765 * @alarm: ptr to alarmtimer
766 * @absexp: absolute expiration time
767 * @type: alarm type (BOOTTIME/REALTIME).
768 *
769 * Sets the alarm timer and sleeps until it is fired or interrupted.
770 */
771static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
772 enum alarmtimer_type type)
773{
774 struct restart_block *restart;
775 alarm->data = (void *)current;
776 do {
777 set_current_state(TASK_INTERRUPTIBLE);
778 alarm_start(alarm, absexp);
779 if (likely(alarm->data))
780 schedule();
781
782 alarm_cancel(alarm);
783 } while (alarm->data && !signal_pending(current));
784
785 __set_current_state(TASK_RUNNING);
786
787 destroy_hrtimer_on_stack(&alarm->timer);
788
789 if (!alarm->data)
790 return 0;
791
792 if (freezing(current))
793 alarmtimer_freezerset(absexp, type);
794 restart = ¤t->restart_block;
795 if (restart->nanosleep.type != TT_NONE) {
796 struct timespec64 rmt;
797 ktime_t rem;
798
799 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
800
801 if (rem <= 0)
802 return 0;
803 rmt = ktime_to_timespec64(rem);
804
805 return nanosleep_copyout(restart, &rmt);
806 }
807 return -ERESTART_RESTARTBLOCK;
808}
809
810static void
811alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
812 enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
813{
814 hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
815 HRTIMER_MODE_ABS);
816 __alarm_init(alarm, type, function);
817}
818
819/**
820 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
821 * @restart: ptr to restart block
822 *
823 * Handles restarted clock_nanosleep calls
824 */
825static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
826{
827 enum alarmtimer_type type = restart->nanosleep.clockid;
828 ktime_t exp = restart->nanosleep.expires;
829 struct alarm alarm;
830
831 alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
832
833 return alarmtimer_do_nsleep(&alarm, exp, type);
834}
835
836/**
837 * alarm_timer_nsleep - alarmtimer nanosleep
838 * @which_clock: clockid
839 * @flags: determines abstime or relative
840 * @tsreq: requested sleep time (abs or rel)
841 *
842 * Handles clock_nanosleep calls against _ALARM clockids
843 */
844static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
845 const struct timespec64 *tsreq)
846{
847 enum alarmtimer_type type = clock2alarm(which_clock);
848 struct restart_block *restart = ¤t->restart_block;
849 struct alarm alarm;
850 ktime_t exp;
851 int ret = 0;
852
853 if (!alarmtimer_get_rtcdev())
854 return -EOPNOTSUPP;
855
856 if (flags & ~TIMER_ABSTIME)
857 return -EINVAL;
858
859 if (!capable(CAP_WAKE_ALARM))
860 return -EPERM;
861
862 alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
863
864 exp = timespec64_to_ktime(*tsreq);
865 /* Convert (if necessary) to absolute time */
866 if (flags != TIMER_ABSTIME) {
867 ktime_t now = alarm_bases[type].get_ktime();
868
869 exp = ktime_add_safe(now, exp);
870 } else {
871 exp = timens_ktime_to_host(which_clock, exp);
872 }
873
874 ret = alarmtimer_do_nsleep(&alarm, exp, type);
875 if (ret != -ERESTART_RESTARTBLOCK)
876 return ret;
877
878 /* abs timers don't set remaining time or restart */
879 if (flags == TIMER_ABSTIME)
880 return -ERESTARTNOHAND;
881
882 restart->nanosleep.clockid = type;
883 restart->nanosleep.expires = exp;
884 set_restart_fn(restart, alarm_timer_nsleep_restart);
885 return ret;
886}
887
888const struct k_clock alarm_clock = {
889 .clock_getres = alarm_clock_getres,
890 .clock_get_ktime = alarm_clock_get_ktime,
891 .clock_get_timespec = alarm_clock_get_timespec,
892 .timer_create = alarm_timer_create,
893 .timer_set = common_timer_set,
894 .timer_del = common_timer_del,
895 .timer_get = common_timer_get,
896 .timer_arm = alarm_timer_arm,
897 .timer_rearm = alarm_timer_rearm,
898 .timer_forward = alarm_timer_forward,
899 .timer_remaining = alarm_timer_remaining,
900 .timer_try_to_cancel = alarm_timer_try_to_cancel,
901 .timer_wait_running = alarm_timer_wait_running,
902 .nsleep = alarm_timer_nsleep,
903};
904#endif /* CONFIG_POSIX_TIMERS */
905
906
907/* Suspend hook structures */
908static const struct dev_pm_ops alarmtimer_pm_ops = {
909 .suspend = alarmtimer_suspend,
910 .resume = alarmtimer_resume,
911};
912
913static struct platform_driver alarmtimer_driver = {
914 .driver = {
915 .name = "alarmtimer",
916 .pm = &alarmtimer_pm_ops,
917 }
918};
919
920static void get_boottime_timespec(struct timespec64 *tp)
921{
922 ktime_get_boottime_ts64(tp);
923 timens_add_boottime(tp);
924}
925
926/**
927 * alarmtimer_init - Initialize alarm timer code
928 *
929 * This function initializes the alarm bases and registers
930 * the posix clock ids.
931 */
932static int __init alarmtimer_init(void)
933{
934 int error;
935 int i;
936
937 alarmtimer_rtc_timer_init();
938
939 /* Initialize alarm bases */
940 alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
941 alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
942 alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
943 alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
944 alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
945 alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
946 for (i = 0; i < ALARM_NUMTYPE; i++) {
947 timerqueue_init_head(&alarm_bases[i].timerqueue);
948 spin_lock_init(&alarm_bases[i].lock);
949 }
950
951 error = alarmtimer_rtc_interface_setup();
952 if (error)
953 return error;
954
955 error = platform_driver_register(&alarmtimer_driver);
956 if (error)
957 goto out_if;
958
959 return 0;
960out_if:
961 alarmtimer_rtc_interface_remove();
962 return error;
963}
964device_initcall(alarmtimer_init);
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 */
37static struct alarm_base {
38 spinlock_t lock;
39 struct timerqueue_head timerqueue;
40 struct hrtimer timer;
41 ktime_t (*gettime)(void);
42 clockid_t base_clockid;
43} alarm_bases[ALARM_NUMTYPE];
44
45/* freezer delta & lock used to handle clock_nanosleep triggered wakeups */
46static ktime_t freezer_delta;
47static DEFINE_SPINLOCK(freezer_delta_lock);
48
49#ifdef CONFIG_RTC_CLASS
50/* rtc timer and device for setting alarm wakeups at suspend */
51static struct rtc_timer rtctimer;
52static struct rtc_device *rtcdev;
53static DEFINE_SPINLOCK(rtcdev_lock);
54
55/**
56 * has_wakealarm - check rtc device has wakealarm ability
57 * @dev: current device
58 * @name_ptr: name to be returned
59 *
60 * This helper function checks to see if the rtc device can wake
61 * from suspend.
62 */
63static int has_wakealarm(struct device *dev, void *name_ptr)
64{
65 struct rtc_device *candidate = to_rtc_device(dev);
66
67 if (!candidate->ops->set_alarm)
68 return 0;
69 if (!device_may_wakeup(candidate->dev.parent))
70 return 0;
71
72 *(const char **)name_ptr = dev_name(dev);
73 return 1;
74}
75
76/**
77 * alarmtimer_get_rtcdev - Return selected rtcdevice
78 *
79 * This function returns the rtc device to use for wakealarms.
80 * If one has not already been chosen, it checks to see if a
81 * functional rtc device is available.
82 */
83static struct rtc_device *alarmtimer_get_rtcdev(void)
84{
85 struct device *dev;
86 char *str;
87 unsigned long flags;
88 struct rtc_device *ret;
89
90 spin_lock_irqsave(&rtcdev_lock, flags);
91 if (!rtcdev) {
92 /* Find an rtc device and init the rtc_timer */
93 dev = class_find_device(rtc_class, NULL, &str, has_wakealarm);
94 /* If we have a device then str is valid. See has_wakealarm() */
95 if (dev) {
96 rtcdev = rtc_class_open(str);
97 /*
98 * Drop the reference we got in class_find_device,
99 * rtc_open takes its own.
100 */
101 put_device(dev);
102 rtc_timer_init(&rtctimer, NULL, NULL);
103 }
104 }
105 ret = rtcdev;
106 spin_unlock_irqrestore(&rtcdev_lock, flags);
107
108 return ret;
109}
110#else
111#define alarmtimer_get_rtcdev() (0)
112#define rtcdev (0)
113#endif
114
115
116/**
117 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
118 * @base: pointer to the base where the timer is being run
119 * @alarm: pointer to alarm being enqueued.
120 *
121 * Adds alarm to a alarm_base timerqueue and if necessary sets
122 * an hrtimer to run.
123 *
124 * Must hold base->lock when calling.
125 */
126static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
127{
128 timerqueue_add(&base->timerqueue, &alarm->node);
129 if (&alarm->node == timerqueue_getnext(&base->timerqueue)) {
130 hrtimer_try_to_cancel(&base->timer);
131 hrtimer_start(&base->timer, alarm->node.expires,
132 HRTIMER_MODE_ABS);
133 }
134}
135
136/**
137 * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue
138 * @base: pointer to the base where the timer is running
139 * @alarm: pointer to alarm being removed
140 *
141 * Removes alarm to a alarm_base timerqueue and if necessary sets
142 * a new timer to run.
143 *
144 * Must hold base->lock when calling.
145 */
146static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm)
147{
148 struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue);
149
150 timerqueue_del(&base->timerqueue, &alarm->node);
151 if (next == &alarm->node) {
152 hrtimer_try_to_cancel(&base->timer);
153 next = timerqueue_getnext(&base->timerqueue);
154 if (!next)
155 return;
156 hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS);
157 }
158}
159
160
161/**
162 * alarmtimer_fired - Handles alarm hrtimer being fired.
163 * @timer: pointer to hrtimer being run
164 *
165 * When a alarm timer fires, this runs through the timerqueue to
166 * see which alarms expired, and runs those. If there are more alarm
167 * timers queued for the future, we set the hrtimer to fire when
168 * when the next future alarm timer expires.
169 */
170static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
171{
172 struct alarm_base *base = container_of(timer, struct alarm_base, timer);
173 struct timerqueue_node *next;
174 unsigned long flags;
175 ktime_t now;
176 int ret = HRTIMER_NORESTART;
177
178 spin_lock_irqsave(&base->lock, flags);
179 now = base->gettime();
180 while ((next = timerqueue_getnext(&base->timerqueue))) {
181 struct alarm *alarm;
182 ktime_t expired = next->expires;
183
184 if (expired.tv64 >= now.tv64)
185 break;
186
187 alarm = container_of(next, struct alarm, node);
188
189 timerqueue_del(&base->timerqueue, &alarm->node);
190 alarm->enabled = 0;
191 /* Re-add periodic timers */
192 if (alarm->period.tv64) {
193 alarm->node.expires = ktime_add(expired, alarm->period);
194 timerqueue_add(&base->timerqueue, &alarm->node);
195 alarm->enabled = 1;
196 }
197 spin_unlock_irqrestore(&base->lock, flags);
198 if (alarm->function)
199 alarm->function(alarm);
200 spin_lock_irqsave(&base->lock, flags);
201 }
202
203 if (next) {
204 hrtimer_set_expires(&base->timer, next->expires);
205 ret = HRTIMER_RESTART;
206 }
207 spin_unlock_irqrestore(&base->lock, flags);
208
209 return ret;
210
211}
212
213#ifdef CONFIG_RTC_CLASS
214/**
215 * alarmtimer_suspend - Suspend time callback
216 * @dev: unused
217 * @state: unused
218 *
219 * When we are going into suspend, we look through the bases
220 * to see which is the soonest timer to expire. We then
221 * set an rtc timer to fire that far into the future, which
222 * will wake us from suspend.
223 */
224static int alarmtimer_suspend(struct device *dev)
225{
226 struct rtc_time tm;
227 ktime_t min, now;
228 unsigned long flags;
229 struct rtc_device *rtc;
230 int i;
231
232 spin_lock_irqsave(&freezer_delta_lock, flags);
233 min = freezer_delta;
234 freezer_delta = ktime_set(0, 0);
235 spin_unlock_irqrestore(&freezer_delta_lock, flags);
236
237 rtc = rtcdev;
238 /* If we have no rtcdev, just return */
239 if (!rtc)
240 return 0;
241
242 /* Find the soonest timer to expire*/
243 for (i = 0; i < ALARM_NUMTYPE; i++) {
244 struct alarm_base *base = &alarm_bases[i];
245 struct timerqueue_node *next;
246 ktime_t delta;
247
248 spin_lock_irqsave(&base->lock, flags);
249 next = timerqueue_getnext(&base->timerqueue);
250 spin_unlock_irqrestore(&base->lock, flags);
251 if (!next)
252 continue;
253 delta = ktime_sub(next->expires, base->gettime());
254 if (!min.tv64 || (delta.tv64 < min.tv64))
255 min = delta;
256 }
257 if (min.tv64 == 0)
258 return 0;
259
260 /* XXX - Should we enforce a minimum sleep time? */
261 WARN_ON(min.tv64 < NSEC_PER_SEC);
262
263 /* Setup an rtc timer to fire that far in the future */
264 rtc_timer_cancel(rtc, &rtctimer);
265 rtc_read_time(rtc, &tm);
266 now = rtc_tm_to_ktime(tm);
267 now = ktime_add(now, min);
268
269 rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0));
270
271 return 0;
272}
273#else
274static int alarmtimer_suspend(struct device *dev)
275{
276 return 0;
277}
278#endif
279
280static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
281{
282 ktime_t delta;
283 unsigned long flags;
284 struct alarm_base *base = &alarm_bases[type];
285
286 delta = ktime_sub(absexp, base->gettime());
287
288 spin_lock_irqsave(&freezer_delta_lock, flags);
289 if (!freezer_delta.tv64 || (delta.tv64 < freezer_delta.tv64))
290 freezer_delta = delta;
291 spin_unlock_irqrestore(&freezer_delta_lock, flags);
292}
293
294
295/**
296 * alarm_init - Initialize an alarm structure
297 * @alarm: ptr to alarm to be initialized
298 * @type: the type of the alarm
299 * @function: callback that is run when the alarm fires
300 */
301void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
302 void (*function)(struct alarm *))
303{
304 timerqueue_init(&alarm->node);
305 alarm->period = ktime_set(0, 0);
306 alarm->function = function;
307 alarm->type = type;
308 alarm->enabled = 0;
309}
310
311/**
312 * alarm_start - Sets an alarm to fire
313 * @alarm: ptr to alarm to set
314 * @start: time to run the alarm
315 * @period: period at which the alarm will recur
316 */
317void alarm_start(struct alarm *alarm, ktime_t start, ktime_t period)
318{
319 struct alarm_base *base = &alarm_bases[alarm->type];
320 unsigned long flags;
321
322 spin_lock_irqsave(&base->lock, flags);
323 if (alarm->enabled)
324 alarmtimer_remove(base, alarm);
325 alarm->node.expires = start;
326 alarm->period = period;
327 alarmtimer_enqueue(base, alarm);
328 alarm->enabled = 1;
329 spin_unlock_irqrestore(&base->lock, flags);
330}
331
332/**
333 * alarm_cancel - Tries to cancel an alarm timer
334 * @alarm: ptr to alarm to be canceled
335 */
336void alarm_cancel(struct alarm *alarm)
337{
338 struct alarm_base *base = &alarm_bases[alarm->type];
339 unsigned long flags;
340
341 spin_lock_irqsave(&base->lock, flags);
342 if (alarm->enabled)
343 alarmtimer_remove(base, alarm);
344 alarm->enabled = 0;
345 spin_unlock_irqrestore(&base->lock, flags);
346}
347
348
349/**
350 * clock2alarm - helper that converts from clockid to alarmtypes
351 * @clockid: clockid.
352 */
353static enum alarmtimer_type clock2alarm(clockid_t clockid)
354{
355 if (clockid == CLOCK_REALTIME_ALARM)
356 return ALARM_REALTIME;
357 if (clockid == CLOCK_BOOTTIME_ALARM)
358 return ALARM_BOOTTIME;
359 return -1;
360}
361
362/**
363 * alarm_handle_timer - Callback for posix timers
364 * @alarm: alarm that fired
365 *
366 * Posix timer callback for expired alarm timers.
367 */
368static void alarm_handle_timer(struct alarm *alarm)
369{
370 struct k_itimer *ptr = container_of(alarm, struct k_itimer,
371 it.alarmtimer);
372 if (posix_timer_event(ptr, 0) != 0)
373 ptr->it_overrun++;
374}
375
376/**
377 * alarm_clock_getres - posix getres interface
378 * @which_clock: clockid
379 * @tp: timespec to fill
380 *
381 * Returns the granularity of underlying alarm base clock
382 */
383static int alarm_clock_getres(const clockid_t which_clock, struct timespec *tp)
384{
385 clockid_t baseid = alarm_bases[clock2alarm(which_clock)].base_clockid;
386
387 if (!alarmtimer_get_rtcdev())
388 return -ENOTSUPP;
389
390 return hrtimer_get_res(baseid, tp);
391}
392
393/**
394 * alarm_clock_get - posix clock_get interface
395 * @which_clock: clockid
396 * @tp: timespec to fill.
397 *
398 * Provides the underlying alarm base time.
399 */
400static int alarm_clock_get(clockid_t which_clock, struct timespec *tp)
401{
402 struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
403
404 if (!alarmtimer_get_rtcdev())
405 return -ENOTSUPP;
406
407 *tp = ktime_to_timespec(base->gettime());
408 return 0;
409}
410
411/**
412 * alarm_timer_create - posix timer_create interface
413 * @new_timer: k_itimer pointer to manage
414 *
415 * Initializes the k_itimer structure.
416 */
417static int alarm_timer_create(struct k_itimer *new_timer)
418{
419 enum alarmtimer_type type;
420 struct alarm_base *base;
421
422 if (!alarmtimer_get_rtcdev())
423 return -ENOTSUPP;
424
425 if (!capable(CAP_WAKE_ALARM))
426 return -EPERM;
427
428 type = clock2alarm(new_timer->it_clock);
429 base = &alarm_bases[type];
430 alarm_init(&new_timer->it.alarmtimer, type, alarm_handle_timer);
431 return 0;
432}
433
434/**
435 * alarm_timer_get - posix timer_get interface
436 * @new_timer: k_itimer pointer
437 * @cur_setting: itimerspec data to fill
438 *
439 * Copies the itimerspec data out from the k_itimer
440 */
441static void alarm_timer_get(struct k_itimer *timr,
442 struct itimerspec *cur_setting)
443{
444 memset(cur_setting, 0, sizeof(struct itimerspec));
445
446 cur_setting->it_interval =
447 ktime_to_timespec(timr->it.alarmtimer.period);
448 cur_setting->it_value =
449 ktime_to_timespec(timr->it.alarmtimer.node.expires);
450 return;
451}
452
453/**
454 * alarm_timer_del - posix timer_del interface
455 * @timr: k_itimer pointer to be deleted
456 *
457 * Cancels any programmed alarms for the given timer.
458 */
459static int alarm_timer_del(struct k_itimer *timr)
460{
461 if (!rtcdev)
462 return -ENOTSUPP;
463
464 alarm_cancel(&timr->it.alarmtimer);
465 return 0;
466}
467
468/**
469 * alarm_timer_set - posix timer_set interface
470 * @timr: k_itimer pointer to be deleted
471 * @flags: timer flags
472 * @new_setting: itimerspec to be used
473 * @old_setting: itimerspec being replaced
474 *
475 * Sets the timer to new_setting, and starts the timer.
476 */
477static int alarm_timer_set(struct k_itimer *timr, int flags,
478 struct itimerspec *new_setting,
479 struct itimerspec *old_setting)
480{
481 if (!rtcdev)
482 return -ENOTSUPP;
483
484 /*
485 * XXX HACK! Currently we can DOS a system if the interval
486 * period on alarmtimers is too small. Cap the interval here
487 * to 100us and solve this properly in a future patch! -jstultz
488 */
489 if ((new_setting->it_interval.tv_sec == 0) &&
490 (new_setting->it_interval.tv_nsec < 100000))
491 new_setting->it_interval.tv_nsec = 100000;
492
493 if (old_setting)
494 alarm_timer_get(timr, old_setting);
495
496 /* If the timer was already set, cancel it */
497 alarm_cancel(&timr->it.alarmtimer);
498
499 /* start the timer */
500 alarm_start(&timr->it.alarmtimer,
501 timespec_to_ktime(new_setting->it_value),
502 timespec_to_ktime(new_setting->it_interval));
503 return 0;
504}
505
506/**
507 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
508 * @alarm: ptr to alarm that fired
509 *
510 * Wakes up the task that set the alarmtimer
511 */
512static void alarmtimer_nsleep_wakeup(struct alarm *alarm)
513{
514 struct task_struct *task = (struct task_struct *)alarm->data;
515
516 alarm->data = NULL;
517 if (task)
518 wake_up_process(task);
519}
520
521/**
522 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
523 * @alarm: ptr to alarmtimer
524 * @absexp: absolute expiration time
525 *
526 * Sets the alarm timer and sleeps until it is fired or interrupted.
527 */
528static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp)
529{
530 alarm->data = (void *)current;
531 do {
532 set_current_state(TASK_INTERRUPTIBLE);
533 alarm_start(alarm, absexp, ktime_set(0, 0));
534 if (likely(alarm->data))
535 schedule();
536
537 alarm_cancel(alarm);
538 } while (alarm->data && !signal_pending(current));
539
540 __set_current_state(TASK_RUNNING);
541
542 return (alarm->data == NULL);
543}
544
545
546/**
547 * update_rmtp - Update remaining timespec value
548 * @exp: expiration time
549 * @type: timer type
550 * @rmtp: user pointer to remaining timepsec value
551 *
552 * Helper function that fills in rmtp value with time between
553 * now and the exp value
554 */
555static int update_rmtp(ktime_t exp, enum alarmtimer_type type,
556 struct timespec __user *rmtp)
557{
558 struct timespec rmt;
559 ktime_t rem;
560
561 rem = ktime_sub(exp, alarm_bases[type].gettime());
562
563 if (rem.tv64 <= 0)
564 return 0;
565 rmt = ktime_to_timespec(rem);
566
567 if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
568 return -EFAULT;
569
570 return 1;
571
572}
573
574/**
575 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
576 * @restart: ptr to restart block
577 *
578 * Handles restarted clock_nanosleep calls
579 */
580static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
581{
582 enum alarmtimer_type type = restart->nanosleep.clockid;
583 ktime_t exp;
584 struct timespec __user *rmtp;
585 struct alarm alarm;
586 int ret = 0;
587
588 exp.tv64 = restart->nanosleep.expires;
589 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
590
591 if (alarmtimer_do_nsleep(&alarm, exp))
592 goto out;
593
594 if (freezing(current))
595 alarmtimer_freezerset(exp, type);
596
597 rmtp = restart->nanosleep.rmtp;
598 if (rmtp) {
599 ret = update_rmtp(exp, type, rmtp);
600 if (ret <= 0)
601 goto out;
602 }
603
604
605 /* The other values in restart are already filled in */
606 ret = -ERESTART_RESTARTBLOCK;
607out:
608 return ret;
609}
610
611/**
612 * alarm_timer_nsleep - alarmtimer nanosleep
613 * @which_clock: clockid
614 * @flags: determins abstime or relative
615 * @tsreq: requested sleep time (abs or rel)
616 * @rmtp: remaining sleep time saved
617 *
618 * Handles clock_nanosleep calls against _ALARM clockids
619 */
620static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
621 struct timespec *tsreq, struct timespec __user *rmtp)
622{
623 enum alarmtimer_type type = clock2alarm(which_clock);
624 struct alarm alarm;
625 ktime_t exp;
626 int ret = 0;
627 struct restart_block *restart;
628
629 if (!alarmtimer_get_rtcdev())
630 return -ENOTSUPP;
631
632 if (!capable(CAP_WAKE_ALARM))
633 return -EPERM;
634
635 alarm_init(&alarm, type, alarmtimer_nsleep_wakeup);
636
637 exp = timespec_to_ktime(*tsreq);
638 /* Convert (if necessary) to absolute time */
639 if (flags != TIMER_ABSTIME) {
640 ktime_t now = alarm_bases[type].gettime();
641 exp = ktime_add(now, exp);
642 }
643
644 if (alarmtimer_do_nsleep(&alarm, exp))
645 goto out;
646
647 if (freezing(current))
648 alarmtimer_freezerset(exp, type);
649
650 /* abs timers don't set remaining time or restart */
651 if (flags == TIMER_ABSTIME) {
652 ret = -ERESTARTNOHAND;
653 goto out;
654 }
655
656 if (rmtp) {
657 ret = update_rmtp(exp, type, rmtp);
658 if (ret <= 0)
659 goto out;
660 }
661
662 restart = ¤t_thread_info()->restart_block;
663 restart->fn = alarm_timer_nsleep_restart;
664 restart->nanosleep.clockid = type;
665 restart->nanosleep.expires = exp.tv64;
666 restart->nanosleep.rmtp = rmtp;
667 ret = -ERESTART_RESTARTBLOCK;
668
669out:
670 return ret;
671}
672
673
674/* Suspend hook structures */
675static const struct dev_pm_ops alarmtimer_pm_ops = {
676 .suspend = alarmtimer_suspend,
677};
678
679static struct platform_driver alarmtimer_driver = {
680 .driver = {
681 .name = "alarmtimer",
682 .pm = &alarmtimer_pm_ops,
683 }
684};
685
686/**
687 * alarmtimer_init - Initialize alarm timer code
688 *
689 * This function initializes the alarm bases and registers
690 * the posix clock ids.
691 */
692static int __init alarmtimer_init(void)
693{
694 int error = 0;
695 int i;
696 struct k_clock alarm_clock = {
697 .clock_getres = alarm_clock_getres,
698 .clock_get = alarm_clock_get,
699 .timer_create = alarm_timer_create,
700 .timer_set = alarm_timer_set,
701 .timer_del = alarm_timer_del,
702 .timer_get = alarm_timer_get,
703 .nsleep = alarm_timer_nsleep,
704 };
705
706 posix_timers_register_clock(CLOCK_REALTIME_ALARM, &alarm_clock);
707 posix_timers_register_clock(CLOCK_BOOTTIME_ALARM, &alarm_clock);
708
709 /* Initialize alarm bases */
710 alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
711 alarm_bases[ALARM_REALTIME].gettime = &ktime_get_real;
712 alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
713 alarm_bases[ALARM_BOOTTIME].gettime = &ktime_get_boottime;
714 for (i = 0; i < ALARM_NUMTYPE; i++) {
715 timerqueue_init_head(&alarm_bases[i].timerqueue);
716 spin_lock_init(&alarm_bases[i].lock);
717 hrtimer_init(&alarm_bases[i].timer,
718 alarm_bases[i].base_clockid,
719 HRTIMER_MODE_ABS);
720 alarm_bases[i].timer.function = alarmtimer_fired;
721 }
722 error = platform_driver_register(&alarmtimer_driver);
723 platform_device_register_simple("alarmtimer", -1, NULL, 0);
724
725 return error;
726}
727device_initcall(alarmtimer_init);
728