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{
 86	unsigned long flags;
 87	struct rtc_device *rtc = to_rtc_device(dev);
 88	struct platform_device *pdev;
 89	int ret = 0;
 90
 91	if (rtcdev)
 92		return -EBUSY;
 93
 94	if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
 95		return -1;
 96	if (!device_may_wakeup(rtc->dev.parent))
 97		return -1;
 98
 99	pdev = platform_device_register_data(dev, "alarmtimer",
100					     PLATFORM_DEVID_AUTO, NULL, 0);
101	if (!IS_ERR(pdev))
102		device_init_wakeup(&pdev->dev, true);
103
104	spin_lock_irqsave(&rtcdev_lock, flags);
105	if (!IS_ERR(pdev) && !rtcdev) {
106		if (!try_module_get(rtc->owner)) {
107			ret = -1;
108			goto unlock;
109		}
110
111		rtcdev = rtc;
112		/* hold a reference so it doesn't go away */
113		get_device(dev);
114		pdev = NULL;
115	} else {
116		ret = -1;
117	}
118unlock:
119	spin_unlock_irqrestore(&rtcdev_lock, flags);
120
121	platform_device_unregister(pdev);
122
123	return ret;
124}
125
126static inline void alarmtimer_rtc_timer_init(void)
127{
128	rtc_timer_init(&rtctimer, NULL, NULL);
129}
130
131static struct class_interface alarmtimer_rtc_interface = {
132	.add_dev = &alarmtimer_rtc_add_device,
133};
134
135static int alarmtimer_rtc_interface_setup(void)
136{
137	alarmtimer_rtc_interface.class = rtc_class;
138	return class_interface_register(&alarmtimer_rtc_interface);
139}
140static void alarmtimer_rtc_interface_remove(void)
141{
142	class_interface_unregister(&alarmtimer_rtc_interface);
143}
144#else
145static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
146static inline void alarmtimer_rtc_interface_remove(void) { }
147static inline void alarmtimer_rtc_timer_init(void) { }
148#endif
149
150/**
151 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
152 * @base: pointer to the base where the timer is being run
153 * @alarm: pointer to alarm being enqueued.
154 *
155 * Adds alarm to a alarm_base timerqueue
156 *
157 * Must hold base->lock when calling.
158 */
159static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
160{
161	if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
162		timerqueue_del(&base->timerqueue, &alarm->node);
163
164	timerqueue_add(&base->timerqueue, &alarm->node);
165	alarm->state |= ALARMTIMER_STATE_ENQUEUED;
166}
167
168/**
169 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
170 * @base: pointer to the base where the timer is running
171 * @alarm: pointer to alarm being removed
172 *
173 * Removes alarm to a alarm_base timerqueue
174 *
175 * Must hold base->lock when calling.
176 */
177static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
178{
179	if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
180		return;
181
182	timerqueue_del(&base->timerqueue, &alarm->node);
183	alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
184}
185
186
187/**
188 * alarmtimer_fired - Handles alarm hrtimer being fired.
189 * @timer: pointer to hrtimer being run
190 *
191 * When a alarm timer fires, this runs through the timerqueue to
192 * see which alarms expired, and runs those. If there are more alarm
193 * timers queued for the future, we set the hrtimer to fire when
194 * the next future alarm timer expires.
195 */
196static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
197{
198	struct alarm *alarm = container_of(timer, struct alarm, timer);
199	struct alarm_base *base = &alarm_bases[alarm->type];
200	unsigned long flags;
201	int ret = HRTIMER_NORESTART;
202	int restart = ALARMTIMER_NORESTART;
203
204	spin_lock_irqsave(&base->lock, flags);
205	alarmtimer_dequeue(base, alarm);
206	spin_unlock_irqrestore(&base->lock, flags);
207
208	if (alarm->function)
209		restart = alarm->function(alarm, base->get_ktime());
210
211	spin_lock_irqsave(&base->lock, flags);
212	if (restart != ALARMTIMER_NORESTART) {
213		hrtimer_set_expires(&alarm->timer, alarm->node.expires);
214		alarmtimer_enqueue(base, alarm);
215		ret = HRTIMER_RESTART;
216	}
217	spin_unlock_irqrestore(&base->lock, flags);
218
219	trace_alarmtimer_fired(alarm, base->get_ktime());
220	return ret;
221
222}
223
224ktime_t alarm_expires_remaining(const struct alarm *alarm)
225{
226	struct alarm_base *base = &alarm_bases[alarm->type];
227	return ktime_sub(alarm->node.expires, base->get_ktime());
228}
229EXPORT_SYMBOL_GPL(alarm_expires_remaining);
230
231#ifdef CONFIG_RTC_CLASS
232/**
233 * alarmtimer_suspend - Suspend time callback
234 * @dev: unused
235 *
236 * When we are going into suspend, we look through the bases
237 * to see which is the soonest timer to expire. We then
238 * set an rtc timer to fire that far into the future, which
239 * will wake us from suspend.
240 */
241static int alarmtimer_suspend(struct device *dev)
242{
243	ktime_t min, now, expires;
244	int i, ret, type;
245	struct rtc_device *rtc;
246	unsigned long flags;
247	struct rtc_time tm;
248
249	spin_lock_irqsave(&freezer_delta_lock, flags);
250	min = freezer_delta;
251	expires = freezer_expires;
252	type = freezer_alarmtype;
253	freezer_delta = 0;
254	spin_unlock_irqrestore(&freezer_delta_lock, flags);
255
256	rtc = alarmtimer_get_rtcdev();
257	/* If we have no rtcdev, just return */
258	if (!rtc)
259		return 0;
260
261	/* Find the soonest timer to expire*/
262	for (i = 0; i < ALARM_NUMTYPE; i++) {
263		struct alarm_base *base = &alarm_bases[i];
264		struct timerqueue_node *next;
265		ktime_t delta;
266
267		spin_lock_irqsave(&base->lock, flags);
268		next = timerqueue_getnext(&base->timerqueue);
269		spin_unlock_irqrestore(&base->lock, flags);
270		if (!next)
271			continue;
272		delta = ktime_sub(next->expires, base->get_ktime());
273		if (!min || (delta < min)) {
274			expires = next->expires;
275			min = delta;
276			type = i;
277		}
278	}
279	if (min == 0)
280		return 0;
281
282	if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
283		pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
284		return -EBUSY;
285	}
286
287	trace_alarmtimer_suspend(expires, type);
288
289	/* Setup an rtc timer to fire that far in the future */
290	rtc_timer_cancel(rtc, &rtctimer);
291	rtc_read_time(rtc, &tm);
292	now = rtc_tm_to_ktime(tm);
293
294	/*
295	 * If the RTC alarm timer only supports a limited time offset, set the
296	 * alarm time to the maximum supported value.
297	 * The system may wake up earlier (possibly much earlier) than expected
298	 * when the alarmtimer runs. This is the best the kernel can do if
299	 * the alarmtimer exceeds the time that the rtc device can be programmed
300	 * for.
301	 */
302	min = rtc_bound_alarmtime(rtc, min);
303
304	now = ktime_add(now, min);
305
306	/* Set alarm, if in the past reject suspend briefly to handle */
307	ret = rtc_timer_start(rtc, &rtctimer, now, 0);
308	if (ret < 0)
309		pm_wakeup_event(dev, MSEC_PER_SEC);
310	return ret;
311}
312
313static int alarmtimer_resume(struct device *dev)
314{
315	struct rtc_device *rtc;
316
317	rtc = alarmtimer_get_rtcdev();
318	if (rtc)
319		rtc_timer_cancel(rtc, &rtctimer);
320	return 0;
321}
322
323#else
324static int alarmtimer_suspend(struct device *dev)
325{
326	return 0;
327}
328
329static int alarmtimer_resume(struct device *dev)
330{
331	return 0;
332}
333#endif
334
335static void
336__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
337	     enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
338{
339	timerqueue_init(&alarm->node);
340	alarm->timer.function = alarmtimer_fired;
341	alarm->function = function;
342	alarm->type = type;
343	alarm->state = ALARMTIMER_STATE_INACTIVE;
344}
345
346/**
347 * alarm_init - Initialize an alarm structure
348 * @alarm: ptr to alarm to be initialized
349 * @type: the type of the alarm
350 * @function: callback that is run when the alarm fires
351 */
352void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
353		enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
354{
355	hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid,
356		     HRTIMER_MODE_ABS);
357	__alarm_init(alarm, type, function);
358}
359EXPORT_SYMBOL_GPL(alarm_init);
360
361/**
362 * alarm_start - Sets an absolute alarm to fire
363 * @alarm: ptr to alarm to set
364 * @start: time to run the alarm
365 */
366void alarm_start(struct alarm *alarm, ktime_t start)
367{
368	struct alarm_base *base = &alarm_bases[alarm->type];
369	unsigned long flags;
370
371	spin_lock_irqsave(&base->lock, flags);
372	alarm->node.expires = start;
373	alarmtimer_enqueue(base, alarm);
374	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
375	spin_unlock_irqrestore(&base->lock, flags);
376
377	trace_alarmtimer_start(alarm, base->get_ktime());
378}
379EXPORT_SYMBOL_GPL(alarm_start);
380
381/**
382 * alarm_start_relative - Sets a relative alarm to fire
383 * @alarm: ptr to alarm to set
384 * @start: time relative to now to run the alarm
385 */
386void alarm_start_relative(struct alarm *alarm, ktime_t start)
387{
388	struct alarm_base *base = &alarm_bases[alarm->type];
389
390	start = ktime_add_safe(start, base->get_ktime());
391	alarm_start(alarm, start);
392}
393EXPORT_SYMBOL_GPL(alarm_start_relative);
394
395void alarm_restart(struct alarm *alarm)
396{
397	struct alarm_base *base = &alarm_bases[alarm->type];
398	unsigned long flags;
399
400	spin_lock_irqsave(&base->lock, flags);
401	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
402	hrtimer_restart(&alarm->timer);
403	alarmtimer_enqueue(base, alarm);
404	spin_unlock_irqrestore(&base->lock, flags);
405}
406EXPORT_SYMBOL_GPL(alarm_restart);
407
408/**
409 * alarm_try_to_cancel - Tries to cancel an alarm timer
410 * @alarm: ptr to alarm to be canceled
411 *
412 * Returns 1 if the timer was canceled, 0 if it was not running,
413 * and -1 if the callback was running
414 */
415int alarm_try_to_cancel(struct alarm *alarm)
416{
417	struct alarm_base *base = &alarm_bases[alarm->type];
418	unsigned long flags;
419	int ret;
420
421	spin_lock_irqsave(&base->lock, flags);
422	ret = hrtimer_try_to_cancel(&alarm->timer);
423	if (ret >= 0)
424		alarmtimer_dequeue(base, alarm);
425	spin_unlock_irqrestore(&base->lock, flags);
426
427	trace_alarmtimer_cancel(alarm, base->get_ktime());
428	return ret;
429}
430EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
431
432
433/**
434 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
435 * @alarm: ptr to alarm to be canceled
436 *
437 * Returns 1 if the timer was canceled, 0 if it was not active.
438 */
439int alarm_cancel(struct alarm *alarm)
440{
441	for (;;) {
442		int ret = alarm_try_to_cancel(alarm);
443		if (ret >= 0)
444			return ret;
445		hrtimer_cancel_wait_running(&alarm->timer);
446	}
447}
448EXPORT_SYMBOL_GPL(alarm_cancel);
449
450
451u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
452{
453	u64 overrun = 1;
454	ktime_t delta;
455
456	delta = ktime_sub(now, alarm->node.expires);
457
458	if (delta < 0)
459		return 0;
460
461	if (unlikely(delta >= interval)) {
462		s64 incr = ktime_to_ns(interval);
463
464		overrun = ktime_divns(delta, incr);
465
466		alarm->node.expires = ktime_add_ns(alarm->node.expires,
467							incr*overrun);
468
469		if (alarm->node.expires > now)
470			return overrun;
471		/*
472		 * This (and the ktime_add() below) is the
473		 * correction for exact:
474		 */
475		overrun++;
476	}
477
478	alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
479	return overrun;
480}
481EXPORT_SYMBOL_GPL(alarm_forward);
482
483static u64 __alarm_forward_now(struct alarm *alarm, ktime_t interval, bool throttle)
484{
485	struct alarm_base *base = &alarm_bases[alarm->type];
486	ktime_t now = base->get_ktime();
487
488	if (IS_ENABLED(CONFIG_HIGH_RES_TIMERS) && throttle) {
489		/*
490		 * Same issue as with posix_timer_fn(). Timers which are
491		 * periodic but the signal is ignored can starve the system
492		 * with a very small interval. The real fix which was
493		 * promised in the context of posix_timer_fn() never
494		 * materialized, but someone should really work on it.
495		 *
496		 * To prevent DOS fake @now to be 1 jiffie out which keeps
497		 * the overrun accounting correct but creates an
498		 * inconsistency vs. timer_gettime(2).
499		 */
500		ktime_t kj = NSEC_PER_SEC / HZ;
501
502		if (interval < kj)
503			now = ktime_add(now, kj);
504	}
505
506	return alarm_forward(alarm, now, interval);
507}
508
509u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
510{
511	return __alarm_forward_now(alarm, interval, false);
512}
513EXPORT_SYMBOL_GPL(alarm_forward_now);
514
515#ifdef CONFIG_POSIX_TIMERS
516
517static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
518{
519	struct alarm_base *base;
520	unsigned long flags;
521	ktime_t delta;
522
523	switch(type) {
524	case ALARM_REALTIME:
525		base = &alarm_bases[ALARM_REALTIME];
526		type = ALARM_REALTIME_FREEZER;
527		break;
528	case ALARM_BOOTTIME:
529		base = &alarm_bases[ALARM_BOOTTIME];
530		type = ALARM_BOOTTIME_FREEZER;
531		break;
532	default:
533		WARN_ONCE(1, "Invalid alarm type: %d\n", type);
534		return;
535	}
536
537	delta = ktime_sub(absexp, base->get_ktime());
538
539	spin_lock_irqsave(&freezer_delta_lock, flags);
540	if (!freezer_delta || (delta < freezer_delta)) {
541		freezer_delta = delta;
542		freezer_expires = absexp;
543		freezer_alarmtype = type;
544	}
545	spin_unlock_irqrestore(&freezer_delta_lock, flags);
546}
547
548/**
549 * clock2alarm - helper that converts from clockid to alarmtypes
550 * @clockid: clockid.
551 */
552static enum alarmtimer_type clock2alarm(clockid_t clockid)
553{
554	if (clockid == CLOCK_REALTIME_ALARM)
555		return ALARM_REALTIME;
556	if (clockid == CLOCK_BOOTTIME_ALARM)
557		return ALARM_BOOTTIME;
558	return -1;
559}
560
561/**
562 * alarm_handle_timer - Callback for posix timers
563 * @alarm: alarm that fired
564 * @now: time at the timer expiration
565 *
566 * Posix timer callback for expired alarm timers.
567 *
568 * Return: whether the timer is to be restarted
569 */
570static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
571							ktime_t now)
572{
573	struct k_itimer *ptr = container_of(alarm, struct k_itimer,
574					    it.alarm.alarmtimer);
575	enum alarmtimer_restart result = ALARMTIMER_NORESTART;
576	unsigned long flags;
577	int si_private = 0;
578
579	spin_lock_irqsave(&ptr->it_lock, flags);
580
581	ptr->it_active = 0;
582	if (ptr->it_interval)
583		si_private = ++ptr->it_requeue_pending;
584
585	if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
586		/*
587		 * Handle ignored signals and rearm the timer. This will go
588		 * away once we handle ignored signals proper. Ensure that
589		 * small intervals cannot starve the system.
590		 */
591		ptr->it_overrun += __alarm_forward_now(alarm, ptr->it_interval, true);
592		++ptr->it_requeue_pending;
593		ptr->it_active = 1;
594		result = ALARMTIMER_RESTART;
595	}
596	spin_unlock_irqrestore(&ptr->it_lock, flags);
597
598	return result;
599}
600
601/**
602 * alarm_timer_rearm - Posix timer callback for rearming timer
603 * @timr:	Pointer to the posixtimer data struct
604 */
605static void alarm_timer_rearm(struct k_itimer *timr)
606{
607	struct alarm *alarm = &timr->it.alarm.alarmtimer;
608
609	timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
610	alarm_start(alarm, alarm->node.expires);
611}
612
613/**
614 * alarm_timer_forward - Posix timer callback for forwarding timer
615 * @timr:	Pointer to the posixtimer data struct
616 * @now:	Current time to forward the timer against
617 */
618static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
619{
620	struct alarm *alarm = &timr->it.alarm.alarmtimer;
621
622	return alarm_forward(alarm, timr->it_interval, now);
623}
624
625/**
626 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
627 * @timr:	Pointer to the posixtimer data struct
628 * @now:	Current time to calculate against
629 */
630static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
631{
632	struct alarm *alarm = &timr->it.alarm.alarmtimer;
633
634	return ktime_sub(alarm->node.expires, now);
635}
636
637/**
638 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
639 * @timr:	Pointer to the posixtimer data struct
640 */
641static int alarm_timer_try_to_cancel(struct k_itimer *timr)
642{
643	return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
644}
645
646/**
647 * alarm_timer_wait_running - Posix timer callback to wait for a timer
648 * @timr:	Pointer to the posixtimer data struct
649 *
650 * Called from the core code when timer cancel detected that the callback
651 * is running. @timr is unlocked and rcu read lock is held to prevent it
652 * from being freed.
653 */
654static void alarm_timer_wait_running(struct k_itimer *timr)
655{
656	hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
657}
658
659/**
660 * alarm_timer_arm - Posix timer callback to arm a timer
661 * @timr:	Pointer to the posixtimer data struct
662 * @expires:	The new expiry time
663 * @absolute:	Expiry value is absolute time
664 * @sigev_none:	Posix timer does not deliver signals
665 */
666static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
667			    bool absolute, bool sigev_none)
668{
669	struct alarm *alarm = &timr->it.alarm.alarmtimer;
670	struct alarm_base *base = &alarm_bases[alarm->type];
671
672	if (!absolute)
673		expires = ktime_add_safe(expires, base->get_ktime());
674	if (sigev_none)
675		alarm->node.expires = expires;
676	else
677		alarm_start(&timr->it.alarm.alarmtimer, expires);
678}
679
680/**
681 * alarm_clock_getres - posix getres interface
682 * @which_clock: clockid
683 * @tp: timespec to fill
684 *
685 * Returns the granularity of underlying alarm base clock
686 */
687static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
688{
689	if (!alarmtimer_get_rtcdev())
690		return -EINVAL;
691
692	tp->tv_sec = 0;
693	tp->tv_nsec = hrtimer_resolution;
694	return 0;
695}
696
697/**
698 * alarm_clock_get_timespec - posix clock_get_timespec interface
699 * @which_clock: clockid
700 * @tp: timespec to fill.
701 *
702 * Provides the underlying alarm base time in a tasks time namespace.
703 */
704static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
705{
706	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
707
708	if (!alarmtimer_get_rtcdev())
709		return -EINVAL;
710
711	base->get_timespec(tp);
712
713	return 0;
714}
715
716/**
717 * alarm_clock_get_ktime - posix clock_get_ktime interface
718 * @which_clock: clockid
719 *
720 * Provides the underlying alarm base time in the root namespace.
721 */
722static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
723{
724	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
725
726	if (!alarmtimer_get_rtcdev())
727		return -EINVAL;
728
729	return base->get_ktime();
730}
731
732/**
733 * alarm_timer_create - posix timer_create interface
734 * @new_timer: k_itimer pointer to manage
735 *
736 * Initializes the k_itimer structure.
737 */
738static int alarm_timer_create(struct k_itimer *new_timer)
739{
740	enum  alarmtimer_type type;
741
742	if (!alarmtimer_get_rtcdev())
743		return -EOPNOTSUPP;
744
745	if (!capable(CAP_WAKE_ALARM))
746		return -EPERM;
747
748	type = clock2alarm(new_timer->it_clock);
749	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
750	return 0;
751}
752
753/**
754 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
755 * @alarm: ptr to alarm that fired
756 * @now: time at the timer expiration
757 *
758 * Wakes up the task that set the alarmtimer
759 *
760 * Return: ALARMTIMER_NORESTART
761 */
762static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
763								ktime_t now)
764{
765	struct task_struct *task = alarm->data;
766
767	alarm->data = NULL;
768	if (task)
769		wake_up_process(task);
770	return ALARMTIMER_NORESTART;
771}
772
773/**
774 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
775 * @alarm: ptr to alarmtimer
776 * @absexp: absolute expiration time
777 * @type: alarm type (BOOTTIME/REALTIME).
778 *
779 * Sets the alarm timer and sleeps until it is fired or interrupted.
780 */
781static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
782				enum alarmtimer_type type)
783{
784	struct restart_block *restart;
785	alarm->data = (void *)current;
786	do {
787		set_current_state(TASK_INTERRUPTIBLE);
788		alarm_start(alarm, absexp);
789		if (likely(alarm->data))
790			schedule();
791
792		alarm_cancel(alarm);
793	} while (alarm->data && !signal_pending(current));
794
795	__set_current_state(TASK_RUNNING);
796
797	destroy_hrtimer_on_stack(&alarm->timer);
798
799	if (!alarm->data)
800		return 0;
801
802	if (freezing(current))
803		alarmtimer_freezerset(absexp, type);
804	restart = &current->restart_block;
805	if (restart->nanosleep.type != TT_NONE) {
806		struct timespec64 rmt;
807		ktime_t rem;
808
809		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
810
811		if (rem <= 0)
812			return 0;
813		rmt = ktime_to_timespec64(rem);
814
815		return nanosleep_copyout(restart, &rmt);
816	}
817	return -ERESTART_RESTARTBLOCK;
818}
819
820static void
821alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
822		    enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
823{
824	hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
825			      HRTIMER_MODE_ABS);
826	__alarm_init(alarm, type, function);
827}
828
829/**
830 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
831 * @restart: ptr to restart block
832 *
833 * Handles restarted clock_nanosleep calls
834 */
835static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
836{
837	enum  alarmtimer_type type = restart->nanosleep.clockid;
838	ktime_t exp = restart->nanosleep.expires;
839	struct alarm alarm;
840
841	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
842
843	return alarmtimer_do_nsleep(&alarm, exp, type);
844}
845
846/**
847 * alarm_timer_nsleep - alarmtimer nanosleep
848 * @which_clock: clockid
849 * @flags: determines abstime or relative
850 * @tsreq: requested sleep time (abs or rel)
851 *
852 * Handles clock_nanosleep calls against _ALARM clockids
853 */
854static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
855			      const struct timespec64 *tsreq)
856{
857	enum  alarmtimer_type type = clock2alarm(which_clock);
858	struct restart_block *restart = &current->restart_block;
859	struct alarm alarm;
860	ktime_t exp;
861	int ret;
862
863	if (!alarmtimer_get_rtcdev())
864		return -EOPNOTSUPP;
865
866	if (flags & ~TIMER_ABSTIME)
867		return -EINVAL;
868
869	if (!capable(CAP_WAKE_ALARM))
870		return -EPERM;
871
872	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
873
874	exp = timespec64_to_ktime(*tsreq);
875	/* Convert (if necessary) to absolute time */
876	if (flags != TIMER_ABSTIME) {
877		ktime_t now = alarm_bases[type].get_ktime();
878
879		exp = ktime_add_safe(now, exp);
880	} else {
881		exp = timens_ktime_to_host(which_clock, exp);
882	}
883
884	ret = alarmtimer_do_nsleep(&alarm, exp, type);
885	if (ret != -ERESTART_RESTARTBLOCK)
886		return ret;
887
888	/* abs timers don't set remaining time or restart */
889	if (flags == TIMER_ABSTIME)
890		return -ERESTARTNOHAND;
891
892	restart->nanosleep.clockid = type;
893	restart->nanosleep.expires = exp;
894	set_restart_fn(restart, alarm_timer_nsleep_restart);
895	return ret;
896}
897
898const struct k_clock alarm_clock = {
899	.clock_getres		= alarm_clock_getres,
900	.clock_get_ktime	= alarm_clock_get_ktime,
901	.clock_get_timespec	= alarm_clock_get_timespec,
902	.timer_create		= alarm_timer_create,
903	.timer_set		= common_timer_set,
904	.timer_del		= common_timer_del,
905	.timer_get		= common_timer_get,
906	.timer_arm		= alarm_timer_arm,
907	.timer_rearm		= alarm_timer_rearm,
908	.timer_forward		= alarm_timer_forward,
909	.timer_remaining	= alarm_timer_remaining,
910	.timer_try_to_cancel	= alarm_timer_try_to_cancel,
911	.timer_wait_running	= alarm_timer_wait_running,
912	.nsleep			= alarm_timer_nsleep,
913};
914#endif /* CONFIG_POSIX_TIMERS */
915
916
917/* Suspend hook structures */
918static const struct dev_pm_ops alarmtimer_pm_ops = {
919	.suspend = alarmtimer_suspend,
920	.resume = alarmtimer_resume,
921};
922
923static struct platform_driver alarmtimer_driver = {
924	.driver = {
925		.name = "alarmtimer",
926		.pm = &alarmtimer_pm_ops,
927	}
928};
929
930static void get_boottime_timespec(struct timespec64 *tp)
931{
932	ktime_get_boottime_ts64(tp);
933	timens_add_boottime(tp);
934}
935
936/**
937 * alarmtimer_init - Initialize alarm timer code
938 *
939 * This function initializes the alarm bases and registers
940 * the posix clock ids.
941 */
942static int __init alarmtimer_init(void)
943{
944	int error;
945	int i;
946
947	alarmtimer_rtc_timer_init();
948
949	/* Initialize alarm bases */
950	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
951	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
952	alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
953	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
954	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
955	alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
956	for (i = 0; i < ALARM_NUMTYPE; i++) {
957		timerqueue_init_head(&alarm_bases[i].timerqueue);
958		spin_lock_init(&alarm_bases[i].lock);
959	}
960
961	error = alarmtimer_rtc_interface_setup();
962	if (error)
963		return error;
964
965	error = platform_driver_register(&alarmtimer_driver);
966	if (error)
967		goto out_if;
968
969	return 0;
970out_if:
971	alarmtimer_rtc_interface_remove();
972	return error;
973}
974device_initcall(alarmtimer_init);