alarmtimer.c

  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 synchronized 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	struct rtc_device *ret;
 74
 75	guard(spinlock_irqsave)(&rtcdev_lock);
 76	ret = rtcdev;
 77
 78	return ret;
 79}
 80EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
 81
 82static int alarmtimer_rtc_add_device(struct device *dev)
 83{
 84	struct rtc_device *rtc = to_rtc_device(dev);
 85	struct platform_device *pdev;
 86	int ret = 0;
 87
 88	if (rtcdev)
 89		return -EBUSY;
 90
 91	if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
 92		return -1;
 93	if (!device_may_wakeup(rtc->dev.parent))
 94		return -1;
 95
 96	pdev = platform_device_register_data(dev, "alarmtimer",
 97					     PLATFORM_DEVID_AUTO, NULL, 0);
 98	if (!IS_ERR(pdev))
 99		device_init_wakeup(&pdev->dev, true);
100
101	scoped_guard(spinlock_irqsave, &rtcdev_lock) {
102		if (!IS_ERR(pdev) && !rtcdev && try_module_get(rtc->owner)) {
103			rtcdev = rtc;
104			/* hold a reference so it doesn't go away */
105			get_device(dev);
106			pdev = NULL;
107		} else {
108			ret = -1;
109		}
110	}
111
112	platform_device_unregister(pdev);
113	return ret;
114}
115
116static inline void alarmtimer_rtc_timer_init(void)
117{
118	rtc_timer_init(&rtctimer, NULL, NULL);
119}
120
121static struct class_interface alarmtimer_rtc_interface = {
122	.add_dev = &alarmtimer_rtc_add_device,
123};
124
125static int alarmtimer_rtc_interface_setup(void)
126{
127	alarmtimer_rtc_interface.class = &rtc_class;
128	return class_interface_register(&alarmtimer_rtc_interface);
129}
130static void alarmtimer_rtc_interface_remove(void)
131{
132	class_interface_unregister(&alarmtimer_rtc_interface);
133}
134#else
135static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
136static inline void alarmtimer_rtc_interface_remove(void) { }
137static inline void alarmtimer_rtc_timer_init(void) { }
138#endif
139
140/**
141 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
142 * @base: pointer to the base where the timer is being run
143 * @alarm: pointer to alarm being enqueued.
144 *
145 * Adds alarm to a alarm_base timerqueue
146 *
147 * Must hold base->lock when calling.
148 */
149static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
150{
151	if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
152		timerqueue_del(&base->timerqueue, &alarm->node);
153
154	timerqueue_add(&base->timerqueue, &alarm->node);
155	alarm->state |= ALARMTIMER_STATE_ENQUEUED;
156}
157
158/**
159 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
160 * @base: pointer to the base where the timer is running
161 * @alarm: pointer to alarm being removed
162 *
163 * Removes alarm to a alarm_base timerqueue
164 *
165 * Must hold base->lock when calling.
166 */
167static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
168{
169	if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
170		return;
171
172	timerqueue_del(&base->timerqueue, &alarm->node);
173	alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
174}
175
176
177/**
178 * alarmtimer_fired - Handles alarm hrtimer being fired.
179 * @timer: pointer to hrtimer being run
180 *
181 * When a alarm timer fires, this runs through the timerqueue to
182 * see which alarms expired, and runs those. If there are more alarm
183 * timers queued for the future, we set the hrtimer to fire when
184 * the next future alarm timer expires.
185 */
186static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
187{
188	struct alarm *alarm = container_of(timer, struct alarm, timer);
189	struct alarm_base *base = &alarm_bases[alarm->type];
190
191	scoped_guard(spinlock_irqsave, &base->lock)
192		alarmtimer_dequeue(base, alarm);
193
194	if (alarm->function)
195		alarm->function(alarm, base->get_ktime());
196
197	trace_alarmtimer_fired(alarm, base->get_ktime());
198	return HRTIMER_NORESTART;
199}
200
201ktime_t alarm_expires_remaining(const struct alarm *alarm)
202{
203	struct alarm_base *base = &alarm_bases[alarm->type];
204	return ktime_sub(alarm->node.expires, base->get_ktime());
205}
206EXPORT_SYMBOL_GPL(alarm_expires_remaining);
207
208#ifdef CONFIG_RTC_CLASS
209/**
210 * alarmtimer_suspend - Suspend time callback
211 * @dev: unused
212 *
213 * When we are going into suspend, we look through the bases
214 * to see which is the soonest timer to expire. We then
215 * set an rtc timer to fire that far into the future, which
216 * will wake us from suspend.
217 */
218static int alarmtimer_suspend(struct device *dev)
219{
220	ktime_t min, now, expires;
221	struct rtc_device *rtc;
222	struct rtc_time tm;
223	int i, ret, type;
224
225	scoped_guard(spinlock_irqsave, &freezer_delta_lock) {
226		min = freezer_delta;
227		expires = freezer_expires;
228		type = freezer_alarmtype;
229		freezer_delta = 0;
230	}
231
232	rtc = alarmtimer_get_rtcdev();
233	/* If we have no rtcdev, just return */
234	if (!rtc)
235		return 0;
236
237	/* Find the soonest timer to expire*/
238	for (i = 0; i < ALARM_NUMTYPE; i++) {
239		struct alarm_base *base = &alarm_bases[i];
240		struct timerqueue_node *next;
241		ktime_t delta;
242
243		scoped_guard(spinlock_irqsave, &base->lock)
244			next = timerqueue_getnext(&base->timerqueue);
245		if (!next)
246			continue;
247		delta = ktime_sub(next->expires, base->get_ktime());
248		if (!min || (delta < min)) {
249			expires = next->expires;
250			min = delta;
251			type = i;
252		}
253	}
254	if (min == 0)
255		return 0;
256
257	if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
258		pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
259		return -EBUSY;
260	}
261
262	trace_alarmtimer_suspend(expires, type);
263
264	/* Setup an rtc timer to fire that far in the future */
265	rtc_timer_cancel(rtc, &rtctimer);
266	rtc_read_time(rtc, &tm);
267	now = rtc_tm_to_ktime(tm);
268
269	/*
270	 * If the RTC alarm timer only supports a limited time offset, set the
271	 * alarm time to the maximum supported value.
272	 * The system may wake up earlier (possibly much earlier) than expected
273	 * when the alarmtimer runs. This is the best the kernel can do if
274	 * the alarmtimer exceeds the time that the rtc device can be programmed
275	 * for.
276	 */
277	min = rtc_bound_alarmtime(rtc, min);
278
279	now = ktime_add(now, min);
280
281	/* Set alarm, if in the past reject suspend briefly to handle */
282	ret = rtc_timer_start(rtc, &rtctimer, now, 0);
283	if (ret < 0)
284		pm_wakeup_event(dev, MSEC_PER_SEC);
285	return ret;
286}
287
288static int alarmtimer_resume(struct device *dev)
289{
290	struct rtc_device *rtc;
291
292	rtc = alarmtimer_get_rtcdev();
293	if (rtc)
294		rtc_timer_cancel(rtc, &rtctimer);
295	return 0;
296}
297
298#else
299static int alarmtimer_suspend(struct device *dev)
300{
301	return 0;
302}
303
304static int alarmtimer_resume(struct device *dev)
305{
306	return 0;
307}
308#endif
309
310static void
311__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
312	     void (*function)(struct alarm *, ktime_t))
313{
314	timerqueue_init(&alarm->node);
315	alarm->function = function;
316	alarm->type = type;
317	alarm->state = ALARMTIMER_STATE_INACTIVE;
318}
319
320/**
321 * alarm_init - Initialize an alarm structure
322 * @alarm: ptr to alarm to be initialized
323 * @type: the type of the alarm
324 * @function: callback that is run when the alarm fires
325 */
326void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
327		void (*function)(struct alarm *, ktime_t))
328{
329	hrtimer_setup(&alarm->timer, alarmtimer_fired, alarm_bases[type].base_clockid,
330		      HRTIMER_MODE_ABS);
331	__alarm_init(alarm, type, function);
332}
333EXPORT_SYMBOL_GPL(alarm_init);
334
335/**
336 * alarm_start - Sets an absolute alarm to fire
337 * @alarm: ptr to alarm to set
338 * @start: time to run the alarm
339 */
340void alarm_start(struct alarm *alarm, ktime_t start)
341{
342	struct alarm_base *base = &alarm_bases[alarm->type];
343
344	scoped_guard(spinlock_irqsave, &base->lock) {
345		alarm->node.expires = start;
346		alarmtimer_enqueue(base, alarm);
347		hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
348	}
349
350	trace_alarmtimer_start(alarm, base->get_ktime());
351}
352EXPORT_SYMBOL_GPL(alarm_start);
353
354/**
355 * alarm_start_relative - Sets a relative alarm to fire
356 * @alarm: ptr to alarm to set
357 * @start: time relative to now to run the alarm
358 */
359void alarm_start_relative(struct alarm *alarm, ktime_t start)
360{
361	struct alarm_base *base = &alarm_bases[alarm->type];
362
363	start = ktime_add_safe(start, base->get_ktime());
364	alarm_start(alarm, start);
365}
366EXPORT_SYMBOL_GPL(alarm_start_relative);
367
368void alarm_restart(struct alarm *alarm)
369{
370	struct alarm_base *base = &alarm_bases[alarm->type];
371
372	guard(spinlock_irqsave)(&base->lock);
373	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
374	hrtimer_restart(&alarm->timer);
375	alarmtimer_enqueue(base, alarm);
376}
377EXPORT_SYMBOL_GPL(alarm_restart);
378
379/**
380 * alarm_try_to_cancel - Tries to cancel an alarm timer
381 * @alarm: ptr to alarm to be canceled
382 *
383 * Returns 1 if the timer was canceled, 0 if it was not running,
384 * and -1 if the callback was running
385 */
386int alarm_try_to_cancel(struct alarm *alarm)
387{
388	struct alarm_base *base = &alarm_bases[alarm->type];
389	int ret;
390
391	scoped_guard(spinlock_irqsave, &base->lock) {
392		ret = hrtimer_try_to_cancel(&alarm->timer);
393		if (ret >= 0)
394			alarmtimer_dequeue(base, alarm);
395	}
396
397	trace_alarmtimer_cancel(alarm, base->get_ktime());
398	return ret;
399}
400EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
401
402
403/**
404 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
405 * @alarm: ptr to alarm to be canceled
406 *
407 * Returns 1 if the timer was canceled, 0 if it was not active.
408 */
409int alarm_cancel(struct alarm *alarm)
410{
411	for (;;) {
412		int ret = alarm_try_to_cancel(alarm);
413		if (ret >= 0)
414			return ret;
415		hrtimer_cancel_wait_running(&alarm->timer);
416	}
417}
418EXPORT_SYMBOL_GPL(alarm_cancel);
419
420
421u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
422{
423	u64 overrun = 1;
424	ktime_t delta;
425
426	delta = ktime_sub(now, alarm->node.expires);
427
428	if (delta < 0)
429		return 0;
430
431	if (unlikely(delta >= interval)) {
432		s64 incr = ktime_to_ns(interval);
433
434		overrun = ktime_divns(delta, incr);
435
436		alarm->node.expires = ktime_add_ns(alarm->node.expires,
437							incr*overrun);
438
439		if (alarm->node.expires > now)
440			return overrun;
441		/*
442		 * This (and the ktime_add() below) is the
443		 * correction for exact:
444		 */
445		overrun++;
446	}
447
448	alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
449	return overrun;
450}
451EXPORT_SYMBOL_GPL(alarm_forward);
452
453u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
454{
455	struct alarm_base *base = &alarm_bases[alarm->type];
456
457	return alarm_forward(alarm, base->get_ktime(), interval);
458}
459EXPORT_SYMBOL_GPL(alarm_forward_now);
460
461#ifdef CONFIG_POSIX_TIMERS
462
463static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
464{
465	struct alarm_base *base;
466	ktime_t delta;
467
468	switch(type) {
469	case ALARM_REALTIME:
470		base = &alarm_bases[ALARM_REALTIME];
471		type = ALARM_REALTIME_FREEZER;
472		break;
473	case ALARM_BOOTTIME:
474		base = &alarm_bases[ALARM_BOOTTIME];
475		type = ALARM_BOOTTIME_FREEZER;
476		break;
477	default:
478		WARN_ONCE(1, "Invalid alarm type: %d\n", type);
479		return;
480	}
481
482	delta = ktime_sub(absexp, base->get_ktime());
483
484	guard(spinlock_irqsave)(&freezer_delta_lock);
485	if (!freezer_delta || (delta < freezer_delta)) {
486		freezer_delta = delta;
487		freezer_expires = absexp;
488		freezer_alarmtype = type;
489	}
490}
491
492/**
493 * clock2alarm - helper that converts from clockid to alarmtypes
494 * @clockid: clockid.
495 */
496static enum alarmtimer_type clock2alarm(clockid_t clockid)
497{
498	if (clockid == CLOCK_REALTIME_ALARM)
499		return ALARM_REALTIME;
500
501	WARN_ON_ONCE(clockid != CLOCK_BOOTTIME_ALARM);
502	return ALARM_BOOTTIME;
503}
504
505/**
506 * alarm_handle_timer - Callback for posix timers
507 * @alarm: alarm that fired
508 * @now: time at the timer expiration
509 *
510 * Posix timer callback for expired alarm timers.
511 *
512 * Return: whether the timer is to be restarted
513 */
514static void alarm_handle_timer(struct alarm *alarm, ktime_t now)
515{
516	struct k_itimer *ptr = container_of(alarm, struct k_itimer, it.alarm.alarmtimer);
517
518	guard(spinlock_irqsave)(&ptr->it_lock);
519	posix_timer_queue_signal(ptr);
520}
521
522/**
523 * alarm_timer_rearm - Posix timer callback for rearming timer
524 * @timr:	Pointer to the posixtimer data struct
525 */
526static void alarm_timer_rearm(struct k_itimer *timr)
527{
528	struct alarm *alarm = &timr->it.alarm.alarmtimer;
529
530	timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
531	alarm_start(alarm, alarm->node.expires);
532}
533
534/**
535 * alarm_timer_forward - Posix timer callback for forwarding timer
536 * @timr:	Pointer to the posixtimer data struct
537 * @now:	Current time to forward the timer against
538 */
539static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
540{
541	struct alarm *alarm = &timr->it.alarm.alarmtimer;
542
543	return alarm_forward(alarm, now, timr->it_interval);
544}
545
546/**
547 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
548 * @timr:	Pointer to the posixtimer data struct
549 * @now:	Current time to calculate against
550 */
551static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
552{
553	struct alarm *alarm = &timr->it.alarm.alarmtimer;
554
555	return ktime_sub(alarm->node.expires, now);
556}
557
558/**
559 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
560 * @timr:	Pointer to the posixtimer data struct
561 */
562static int alarm_timer_try_to_cancel(struct k_itimer *timr)
563{
564	return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
565}
566
567/**
568 * alarm_timer_wait_running - Posix timer callback to wait for a timer
569 * @timr:	Pointer to the posixtimer data struct
570 *
571 * Called from the core code when timer cancel detected that the callback
572 * is running. @timr is unlocked and rcu read lock is held to prevent it
573 * from being freed.
574 */
575static void alarm_timer_wait_running(struct k_itimer *timr)
576{
577	hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
578}
579
580/**
581 * alarm_timer_arm - Posix timer callback to arm a timer
582 * @timr:	Pointer to the posixtimer data struct
583 * @expires:	The new expiry time
584 * @absolute:	Expiry value is absolute time
585 * @sigev_none:	Posix timer does not deliver signals
586 */
587static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
588			    bool absolute, bool sigev_none)
589{
590	struct alarm *alarm = &timr->it.alarm.alarmtimer;
591	struct alarm_base *base = &alarm_bases[alarm->type];
592
593	if (!absolute)
594		expires = ktime_add_safe(expires, base->get_ktime());
595	if (sigev_none)
596		alarm->node.expires = expires;
597	else
598		alarm_start(&timr->it.alarm.alarmtimer, expires);
599}
600
601/**
602 * alarm_clock_getres - posix getres interface
603 * @which_clock: clockid
604 * @tp: timespec to fill
605 *
606 * Returns the granularity of underlying alarm base clock
607 */
608static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
609{
610	if (!alarmtimer_get_rtcdev())
611		return -EINVAL;
612
613	tp->tv_sec = 0;
614	tp->tv_nsec = hrtimer_resolution;
615	return 0;
616}
617
618/**
619 * alarm_clock_get_timespec - posix clock_get_timespec interface
620 * @which_clock: clockid
621 * @tp: timespec to fill.
622 *
623 * Provides the underlying alarm base time in a tasks time namespace.
624 */
625static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
626{
627	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
628
629	if (!alarmtimer_get_rtcdev())
630		return -EINVAL;
631
632	base->get_timespec(tp);
633
634	return 0;
635}
636
637/**
638 * alarm_clock_get_ktime - posix clock_get_ktime interface
639 * @which_clock: clockid
640 *
641 * Provides the underlying alarm base time in the root namespace.
642 */
643static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
644{
645	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
646
647	if (!alarmtimer_get_rtcdev())
648		return -EINVAL;
649
650	return base->get_ktime();
651}
652
653/**
654 * alarm_timer_create - posix timer_create interface
655 * @new_timer: k_itimer pointer to manage
656 *
657 * Initializes the k_itimer structure.
658 */
659static int alarm_timer_create(struct k_itimer *new_timer)
660{
661	enum  alarmtimer_type type;
662
663	if (!alarmtimer_get_rtcdev())
664		return -EOPNOTSUPP;
665
666	if (!capable(CAP_WAKE_ALARM))
667		return -EPERM;
668
669	type = clock2alarm(new_timer->it_clock);
670	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
671	return 0;
672}
673
674/**
675 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
676 * @alarm: ptr to alarm that fired
677 * @now: time at the timer expiration
678 *
679 * Wakes up the task that set the alarmtimer
680 */
681static void alarmtimer_nsleep_wakeup(struct alarm *alarm, ktime_t now)
682{
683	struct task_struct *task = alarm->data;
684
685	alarm->data = NULL;
686	if (task)
687		wake_up_process(task);
688}
689
690/**
691 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
692 * @alarm: ptr to alarmtimer
693 * @absexp: absolute expiration time
694 * @type: alarm type (BOOTTIME/REALTIME).
695 *
696 * Sets the alarm timer and sleeps until it is fired or interrupted.
697 */
698static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
699				enum alarmtimer_type type)
700{
701	struct restart_block *restart;
702	alarm->data = (void *)current;
703	do {
704		set_current_state(TASK_INTERRUPTIBLE);
705		alarm_start(alarm, absexp);
706		if (likely(alarm->data))
707			schedule();
708
709		alarm_cancel(alarm);
710	} while (alarm->data && !signal_pending(current));
711
712	__set_current_state(TASK_RUNNING);
713
714	destroy_hrtimer_on_stack(&alarm->timer);
715
716	if (!alarm->data)
717		return 0;
718
719	if (freezing(current))
720		alarmtimer_freezerset(absexp, type);
721	restart = &current->restart_block;
722	if (restart->nanosleep.type != TT_NONE) {
723		struct timespec64 rmt;
724		ktime_t rem;
725
726		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
727
728		if (rem <= 0)
729			return 0;
730		rmt = ktime_to_timespec64(rem);
731
732		return nanosleep_copyout(restart, &rmt);
733	}
734	return -ERESTART_RESTARTBLOCK;
735}
736
737static void
738alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
739		    void (*function)(struct alarm *, ktime_t))
740{
741	hrtimer_setup_on_stack(&alarm->timer, alarmtimer_fired, alarm_bases[type].base_clockid,
742			       HRTIMER_MODE_ABS);
743	__alarm_init(alarm, type, function);
744}
745
746/**
747 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
748 * @restart: ptr to restart block
749 *
750 * Handles restarted clock_nanosleep calls
751 */
752static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
753{
754	enum  alarmtimer_type type = restart->nanosleep.clockid;
755	ktime_t exp = restart->nanosleep.expires;
756	struct alarm alarm;
757
758	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
759
760	return alarmtimer_do_nsleep(&alarm, exp, type);
761}
762
763/**
764 * alarm_timer_nsleep - alarmtimer nanosleep
765 * @which_clock: clockid
766 * @flags: determines abstime or relative
767 * @tsreq: requested sleep time (abs or rel)
768 *
769 * Handles clock_nanosleep calls against _ALARM clockids
770 */
771static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
772			      const struct timespec64 *tsreq)
773{
774	enum  alarmtimer_type type = clock2alarm(which_clock);
775	struct restart_block *restart = &current->restart_block;
776	struct alarm alarm;
777	ktime_t exp;
778	int ret;
779
780	if (!alarmtimer_get_rtcdev())
781		return -EOPNOTSUPP;
782
783	if (flags & ~TIMER_ABSTIME)
784		return -EINVAL;
785
786	if (!capable(CAP_WAKE_ALARM))
787		return -EPERM;
788
789	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
790
791	exp = timespec64_to_ktime(*tsreq);
792	/* Convert (if necessary) to absolute time */
793	if (flags != TIMER_ABSTIME) {
794		ktime_t now = alarm_bases[type].get_ktime();
795
796		exp = ktime_add_safe(now, exp);
797	} else {
798		exp = timens_ktime_to_host(which_clock, exp);
799	}
800
801	ret = alarmtimer_do_nsleep(&alarm, exp, type);
802	if (ret != -ERESTART_RESTARTBLOCK)
803		return ret;
804
805	/* abs timers don't set remaining time or restart */
806	if (flags == TIMER_ABSTIME)
807		return -ERESTARTNOHAND;
808
809	restart->nanosleep.clockid = type;
810	restart->nanosleep.expires = exp;
811	set_restart_fn(restart, alarm_timer_nsleep_restart);
812	return ret;
813}
814
815const struct k_clock alarm_clock = {
816	.clock_getres		= alarm_clock_getres,
817	.clock_get_ktime	= alarm_clock_get_ktime,
818	.clock_get_timespec	= alarm_clock_get_timespec,
819	.timer_create		= alarm_timer_create,
820	.timer_set		= common_timer_set,
821	.timer_del		= common_timer_del,
822	.timer_get		= common_timer_get,
823	.timer_arm		= alarm_timer_arm,
824	.timer_rearm		= alarm_timer_rearm,
825	.timer_forward		= alarm_timer_forward,
826	.timer_remaining	= alarm_timer_remaining,
827	.timer_try_to_cancel	= alarm_timer_try_to_cancel,
828	.timer_wait_running	= alarm_timer_wait_running,
829	.nsleep			= alarm_timer_nsleep,
830};
831#endif /* CONFIG_POSIX_TIMERS */
832
833
834/* Suspend hook structures */
835static const struct dev_pm_ops alarmtimer_pm_ops = {
836	.suspend = alarmtimer_suspend,
837	.resume = alarmtimer_resume,
838};
839
840static struct platform_driver alarmtimer_driver = {
841	.driver = {
842		.name = "alarmtimer",
843		.pm = &alarmtimer_pm_ops,
844	}
845};
846
847static void get_boottime_timespec(struct timespec64 *tp)
848{
849	ktime_get_boottime_ts64(tp);
850	timens_add_boottime(tp);
851}
852
853/**
854 * alarmtimer_init - Initialize alarm timer code
855 *
856 * This function initializes the alarm bases and registers
857 * the posix clock ids.
858 */
859static int __init alarmtimer_init(void)
860{
861	int error;
862	int i;
863
864	alarmtimer_rtc_timer_init();
865
866	/* Initialize alarm bases */
867	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
868	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
869	alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
870	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
871	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
872	alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
873	for (i = 0; i < ALARM_NUMTYPE; i++) {
874		timerqueue_init_head(&alarm_bases[i].timerqueue);
875		spin_lock_init(&alarm_bases[i].lock);
876	}
877
878	error = alarmtimer_rtc_interface_setup();
879	if (error)
880		return error;
881
882	error = platform_driver_register(&alarmtimer_driver);
883	if (error)
884		goto out_if;
885
886	return 0;
887out_if:
888	alarmtimer_rtc_interface_remove();
889	return error;
890}
891device_initcall(alarmtimer_init);