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
201	scoped_guard (spinlock_irqsave, &base->lock)
202		alarmtimer_dequeue(base, alarm);
 
203
204	if (alarm->function)
205		alarm->function(alarm, base->get_ktime());
 
 
 
 
 
 
 
 
206
207	trace_alarmtimer_fired(alarm, base->get_ktime());
208	return HRTIMER_NORESTART;
 
209}
210
211ktime_t alarm_expires_remaining(const struct alarm *alarm)
212{
213	struct alarm_base *base = &alarm_bases[alarm->type];
214	return ktime_sub(alarm->node.expires, base->get_ktime());
215}
216EXPORT_SYMBOL_GPL(alarm_expires_remaining);
217
218#ifdef CONFIG_RTC_CLASS
219/**
220 * alarmtimer_suspend - Suspend time callback
221 * @dev: unused
222 *
223 * When we are going into suspend, we look through the bases
224 * to see which is the soonest timer to expire. We then
225 * set an rtc timer to fire that far into the future, which
226 * will wake us from suspend.
227 */
228static int alarmtimer_suspend(struct device *dev)
229{
230	ktime_t min, now, expires;
231	int i, ret, type;
232	struct rtc_device *rtc;
233	unsigned long flags;
234	struct rtc_time tm;
235
236	spin_lock_irqsave(&freezer_delta_lock, flags);
237	min = freezer_delta;
238	expires = freezer_expires;
239	type = freezer_alarmtype;
240	freezer_delta = 0;
241	spin_unlock_irqrestore(&freezer_delta_lock, flags);
242
243	rtc = alarmtimer_get_rtcdev();
244	/* If we have no rtcdev, just return */
245	if (!rtc)
246		return 0;
247
248	/* Find the soonest timer to expire*/
249	for (i = 0; i < ALARM_NUMTYPE; i++) {
250		struct alarm_base *base = &alarm_bases[i];
251		struct timerqueue_node *next;
252		ktime_t delta;
253
254		spin_lock_irqsave(&base->lock, flags);
255		next = timerqueue_getnext(&base->timerqueue);
256		spin_unlock_irqrestore(&base->lock, flags);
257		if (!next)
258			continue;
259		delta = ktime_sub(next->expires, base->get_ktime());
260		if (!min || (delta < min)) {
261			expires = next->expires;
262			min = delta;
263			type = i;
264		}
265	}
266	if (min == 0)
267		return 0;
268
269	if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) {
270		pm_wakeup_event(dev, 2 * MSEC_PER_SEC);
271		return -EBUSY;
272	}
273
274	trace_alarmtimer_suspend(expires, type);
275
276	/* Setup an rtc timer to fire that far in the future */
277	rtc_timer_cancel(rtc, &rtctimer);
278	rtc_read_time(rtc, &tm);
279	now = rtc_tm_to_ktime(tm);
280
281	/*
282	 * If the RTC alarm timer only supports a limited time offset, set the
283	 * alarm time to the maximum supported value.
284	 * The system may wake up earlier (possibly much earlier) than expected
285	 * when the alarmtimer runs. This is the best the kernel can do if
286	 * the alarmtimer exceeds the time that the rtc device can be programmed
287	 * for.
288	 */
289	min = rtc_bound_alarmtime(rtc, min);
290
291	now = ktime_add(now, min);
292
293	/* Set alarm, if in the past reject suspend briefly to handle */
294	ret = rtc_timer_start(rtc, &rtctimer, now, 0);
295	if (ret < 0)
296		pm_wakeup_event(dev, MSEC_PER_SEC);
297	return ret;
298}
299
300static int alarmtimer_resume(struct device *dev)
301{
302	struct rtc_device *rtc;
303
304	rtc = alarmtimer_get_rtcdev();
305	if (rtc)
306		rtc_timer_cancel(rtc, &rtctimer);
307	return 0;
308}
309
310#else
311static int alarmtimer_suspend(struct device *dev)
312{
313	return 0;
314}
315
316static int alarmtimer_resume(struct device *dev)
317{
318	return 0;
319}
320#endif
321
322static void
323__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
324	     void (*function)(struct alarm *, ktime_t))
325{
326	timerqueue_init(&alarm->node);
 
327	alarm->function = function;
328	alarm->type = type;
329	alarm->state = ALARMTIMER_STATE_INACTIVE;
330}
331
332/**
333 * alarm_init - Initialize an alarm structure
334 * @alarm: ptr to alarm to be initialized
335 * @type: the type of the alarm
336 * @function: callback that is run when the alarm fires
337 */
338void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
339		void (*function)(struct alarm *, ktime_t))
340{
341	hrtimer_setup(&alarm->timer, alarmtimer_fired, alarm_bases[type].base_clockid,
342		      HRTIMER_MODE_ABS);
343	__alarm_init(alarm, type, function);
344}
345EXPORT_SYMBOL_GPL(alarm_init);
346
347/**
348 * alarm_start - Sets an absolute alarm to fire
349 * @alarm: ptr to alarm to set
350 * @start: time to run the alarm
351 */
352void alarm_start(struct alarm *alarm, ktime_t start)
353{
354	struct alarm_base *base = &alarm_bases[alarm->type];
355	unsigned long flags;
356
357	spin_lock_irqsave(&base->lock, flags);
358	alarm->node.expires = start;
359	alarmtimer_enqueue(base, alarm);
360	hrtimer_start(&alarm->timer, alarm->node.expires, HRTIMER_MODE_ABS);
361	spin_unlock_irqrestore(&base->lock, flags);
362
363	trace_alarmtimer_start(alarm, base->get_ktime());
364}
365EXPORT_SYMBOL_GPL(alarm_start);
366
367/**
368 * alarm_start_relative - Sets a relative alarm to fire
369 * @alarm: ptr to alarm to set
370 * @start: time relative to now to run the alarm
371 */
372void alarm_start_relative(struct alarm *alarm, ktime_t start)
373{
374	struct alarm_base *base = &alarm_bases[alarm->type];
375
376	start = ktime_add_safe(start, base->get_ktime());
377	alarm_start(alarm, start);
378}
379EXPORT_SYMBOL_GPL(alarm_start_relative);
380
381void alarm_restart(struct alarm *alarm)
382{
383	struct alarm_base *base = &alarm_bases[alarm->type];
384	unsigned long flags;
385
386	spin_lock_irqsave(&base->lock, flags);
387	hrtimer_set_expires(&alarm->timer, alarm->node.expires);
388	hrtimer_restart(&alarm->timer);
389	alarmtimer_enqueue(base, alarm);
390	spin_unlock_irqrestore(&base->lock, flags);
391}
392EXPORT_SYMBOL_GPL(alarm_restart);
393
394/**
395 * alarm_try_to_cancel - Tries to cancel an alarm timer
396 * @alarm: ptr to alarm to be canceled
397 *
398 * Returns 1 if the timer was canceled, 0 if it was not running,
399 * and -1 if the callback was running
400 */
401int alarm_try_to_cancel(struct alarm *alarm)
402{
403	struct alarm_base *base = &alarm_bases[alarm->type];
404	unsigned long flags;
405	int ret;
406
407	spin_lock_irqsave(&base->lock, flags);
408	ret = hrtimer_try_to_cancel(&alarm->timer);
409	if (ret >= 0)
410		alarmtimer_dequeue(base, alarm);
411	spin_unlock_irqrestore(&base->lock, flags);
412
413	trace_alarmtimer_cancel(alarm, base->get_ktime());
414	return ret;
415}
416EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
417
418
419/**
420 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
421 * @alarm: ptr to alarm to be canceled
422 *
423 * Returns 1 if the timer was canceled, 0 if it was not active.
424 */
425int alarm_cancel(struct alarm *alarm)
426{
427	for (;;) {
428		int ret = alarm_try_to_cancel(alarm);
429		if (ret >= 0)
430			return ret;
431		hrtimer_cancel_wait_running(&alarm->timer);
432	}
433}
434EXPORT_SYMBOL_GPL(alarm_cancel);
435
436
437u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
438{
439	u64 overrun = 1;
440	ktime_t delta;
441
442	delta = ktime_sub(now, alarm->node.expires);
443
444	if (delta < 0)
445		return 0;
446
447	if (unlikely(delta >= interval)) {
448		s64 incr = ktime_to_ns(interval);
449
450		overrun = ktime_divns(delta, incr);
451
452		alarm->node.expires = ktime_add_ns(alarm->node.expires,
453							incr*overrun);
454
455		if (alarm->node.expires > now)
456			return overrun;
457		/*
458		 * This (and the ktime_add() below) is the
459		 * correction for exact:
460		 */
461		overrun++;
462	}
463
464	alarm->node.expires = ktime_add_safe(alarm->node.expires, interval);
465	return overrun;
466}
467EXPORT_SYMBOL_GPL(alarm_forward);
468
469u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
470{
471	struct alarm_base *base = &alarm_bases[alarm->type];
472
473	return alarm_forward(alarm, base->get_ktime(), interval);
474}
475EXPORT_SYMBOL_GPL(alarm_forward_now);
476
477#ifdef CONFIG_POSIX_TIMERS
478
479static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
480{
481	struct alarm_base *base;
482	unsigned long flags;
483	ktime_t delta;
484
485	switch(type) {
486	case ALARM_REALTIME:
487		base = &alarm_bases[ALARM_REALTIME];
488		type = ALARM_REALTIME_FREEZER;
489		break;
490	case ALARM_BOOTTIME:
491		base = &alarm_bases[ALARM_BOOTTIME];
492		type = ALARM_BOOTTIME_FREEZER;
493		break;
494	default:
495		WARN_ONCE(1, "Invalid alarm type: %d\n", type);
496		return;
497	}
498
499	delta = ktime_sub(absexp, base->get_ktime());
500
501	spin_lock_irqsave(&freezer_delta_lock, flags);
502	if (!freezer_delta || (delta < freezer_delta)) {
503		freezer_delta = delta;
504		freezer_expires = absexp;
505		freezer_alarmtype = type;
506	}
507	spin_unlock_irqrestore(&freezer_delta_lock, flags);
508}
509
510/**
511 * clock2alarm - helper that converts from clockid to alarmtypes
512 * @clockid: clockid.
513 */
514static enum alarmtimer_type clock2alarm(clockid_t clockid)
515{
516	if (clockid == CLOCK_REALTIME_ALARM)
517		return ALARM_REALTIME;
518	if (clockid == CLOCK_BOOTTIME_ALARM)
519		return ALARM_BOOTTIME;
520	return -1;
521}
522
523/**
524 * alarm_handle_timer - Callback for posix timers
525 * @alarm: alarm that fired
526 * @now: time at the timer expiration
527 *
528 * Posix timer callback for expired alarm timers.
529 *
530 * Return: whether the timer is to be restarted
531 */
532static void alarm_handle_timer(struct alarm *alarm, ktime_t now)
 
533{
534	struct k_itimer *ptr = container_of(alarm, struct k_itimer, it.alarm.alarmtimer);
 
 
 
 
 
 
535
536	guard(spinlock_irqsave)(&ptr->it_lock);
537	posix_timer_queue_signal(ptr);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
538}
539
540/**
541 * alarm_timer_rearm - Posix timer callback for rearming timer
542 * @timr:	Pointer to the posixtimer data struct
543 */
544static void alarm_timer_rearm(struct k_itimer *timr)
545{
546	struct alarm *alarm = &timr->it.alarm.alarmtimer;
547
548	timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
549	alarm_start(alarm, alarm->node.expires);
550}
551
552/**
553 * alarm_timer_forward - Posix timer callback for forwarding timer
554 * @timr:	Pointer to the posixtimer data struct
555 * @now:	Current time to forward the timer against
556 */
557static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
558{
559	struct alarm *alarm = &timr->it.alarm.alarmtimer;
560
561	return alarm_forward(alarm, timr->it_interval, now);
562}
563
564/**
565 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
566 * @timr:	Pointer to the posixtimer data struct
567 * @now:	Current time to calculate against
568 */
569static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
570{
571	struct alarm *alarm = &timr->it.alarm.alarmtimer;
572
573	return ktime_sub(alarm->node.expires, now);
574}
575
576/**
577 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
578 * @timr:	Pointer to the posixtimer data struct
579 */
580static int alarm_timer_try_to_cancel(struct k_itimer *timr)
581{
582	return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
583}
584
585/**
586 * alarm_timer_wait_running - Posix timer callback to wait for a timer
587 * @timr:	Pointer to the posixtimer data struct
588 *
589 * Called from the core code when timer cancel detected that the callback
590 * is running. @timr is unlocked and rcu read lock is held to prevent it
591 * from being freed.
592 */
593static void alarm_timer_wait_running(struct k_itimer *timr)
594{
595	hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
596}
597
598/**
599 * alarm_timer_arm - Posix timer callback to arm a timer
600 * @timr:	Pointer to the posixtimer data struct
601 * @expires:	The new expiry time
602 * @absolute:	Expiry value is absolute time
603 * @sigev_none:	Posix timer does not deliver signals
604 */
605static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
606			    bool absolute, bool sigev_none)
607{
608	struct alarm *alarm = &timr->it.alarm.alarmtimer;
609	struct alarm_base *base = &alarm_bases[alarm->type];
610
611	if (!absolute)
612		expires = ktime_add_safe(expires, base->get_ktime());
613	if (sigev_none)
614		alarm->node.expires = expires;
615	else
616		alarm_start(&timr->it.alarm.alarmtimer, expires);
617}
618
619/**
620 * alarm_clock_getres - posix getres interface
621 * @which_clock: clockid
622 * @tp: timespec to fill
623 *
624 * Returns the granularity of underlying alarm base clock
625 */
626static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
627{
628	if (!alarmtimer_get_rtcdev())
629		return -EINVAL;
630
631	tp->tv_sec = 0;
632	tp->tv_nsec = hrtimer_resolution;
633	return 0;
634}
635
636/**
637 * alarm_clock_get_timespec - posix clock_get_timespec interface
638 * @which_clock: clockid
639 * @tp: timespec to fill.
640 *
641 * Provides the underlying alarm base time in a tasks time namespace.
642 */
643static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
644{
645	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
646
647	if (!alarmtimer_get_rtcdev())
648		return -EINVAL;
649
650	base->get_timespec(tp);
651
652	return 0;
653}
654
655/**
656 * alarm_clock_get_ktime - posix clock_get_ktime interface
657 * @which_clock: clockid
658 *
659 * Provides the underlying alarm base time in the root namespace.
660 */
661static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
662{
663	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
664
665	if (!alarmtimer_get_rtcdev())
666		return -EINVAL;
667
668	return base->get_ktime();
669}
670
671/**
672 * alarm_timer_create - posix timer_create interface
673 * @new_timer: k_itimer pointer to manage
674 *
675 * Initializes the k_itimer structure.
676 */
677static int alarm_timer_create(struct k_itimer *new_timer)
678{
679	enum  alarmtimer_type type;
680
681	if (!alarmtimer_get_rtcdev())
682		return -EOPNOTSUPP;
683
684	if (!capable(CAP_WAKE_ALARM))
685		return -EPERM;
686
687	type = clock2alarm(new_timer->it_clock);
688	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
689	return 0;
690}
691
692/**
693 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
694 * @alarm: ptr to alarm that fired
695 * @now: time at the timer expiration
696 *
697 * Wakes up the task that set the alarmtimer
 
 
698 */
699static void alarmtimer_nsleep_wakeup(struct alarm *alarm, ktime_t now)
 
700{
701	struct task_struct *task = alarm->data;
702
703	alarm->data = NULL;
704	if (task)
705		wake_up_process(task);
 
706}
707
708/**
709 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
710 * @alarm: ptr to alarmtimer
711 * @absexp: absolute expiration time
712 * @type: alarm type (BOOTTIME/REALTIME).
713 *
714 * Sets the alarm timer and sleeps until it is fired or interrupted.
715 */
716static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
717				enum alarmtimer_type type)
718{
719	struct restart_block *restart;
720	alarm->data = (void *)current;
721	do {
722		set_current_state(TASK_INTERRUPTIBLE);
723		alarm_start(alarm, absexp);
724		if (likely(alarm->data))
725			schedule();
726
727		alarm_cancel(alarm);
728	} while (alarm->data && !signal_pending(current));
729
730	__set_current_state(TASK_RUNNING);
731
732	destroy_hrtimer_on_stack(&alarm->timer);
733
734	if (!alarm->data)
735		return 0;
736
737	if (freezing(current))
738		alarmtimer_freezerset(absexp, type);
739	restart = &current->restart_block;
740	if (restart->nanosleep.type != TT_NONE) {
741		struct timespec64 rmt;
742		ktime_t rem;
743
744		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
745
746		if (rem <= 0)
747			return 0;
748		rmt = ktime_to_timespec64(rem);
749
750		return nanosleep_copyout(restart, &rmt);
751	}
752	return -ERESTART_RESTARTBLOCK;
753}
754
755static void
756alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
757		    void (*function)(struct alarm *, ktime_t))
758{
759	hrtimer_setup_on_stack(&alarm->timer, alarmtimer_fired, alarm_bases[type].base_clockid,
760			       HRTIMER_MODE_ABS);
761	__alarm_init(alarm, type, function);
762}
763
764/**
765 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
766 * @restart: ptr to restart block
767 *
768 * Handles restarted clock_nanosleep calls
769 */
770static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
771{
772	enum  alarmtimer_type type = restart->nanosleep.clockid;
773	ktime_t exp = restart->nanosleep.expires;
774	struct alarm alarm;
775
776	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
777
778	return alarmtimer_do_nsleep(&alarm, exp, type);
779}
780
781/**
782 * alarm_timer_nsleep - alarmtimer nanosleep
783 * @which_clock: clockid
784 * @flags: determines abstime or relative
785 * @tsreq: requested sleep time (abs or rel)
786 *
787 * Handles clock_nanosleep calls against _ALARM clockids
788 */
789static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
790			      const struct timespec64 *tsreq)
791{
792	enum  alarmtimer_type type = clock2alarm(which_clock);
793	struct restart_block *restart = &current->restart_block;
794	struct alarm alarm;
795	ktime_t exp;
796	int ret;
797
798	if (!alarmtimer_get_rtcdev())
799		return -EOPNOTSUPP;
800
801	if (flags & ~TIMER_ABSTIME)
802		return -EINVAL;
803
804	if (!capable(CAP_WAKE_ALARM))
805		return -EPERM;
806
807	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
808
809	exp = timespec64_to_ktime(*tsreq);
810	/* Convert (if necessary) to absolute time */
811	if (flags != TIMER_ABSTIME) {
812		ktime_t now = alarm_bases[type].get_ktime();
813
814		exp = ktime_add_safe(now, exp);
815	} else {
816		exp = timens_ktime_to_host(which_clock, exp);
817	}
818
819	ret = alarmtimer_do_nsleep(&alarm, exp, type);
820	if (ret != -ERESTART_RESTARTBLOCK)
821		return ret;
822
823	/* abs timers don't set remaining time or restart */
824	if (flags == TIMER_ABSTIME)
825		return -ERESTARTNOHAND;
826
827	restart->nanosleep.clockid = type;
828	restart->nanosleep.expires = exp;
829	set_restart_fn(restart, alarm_timer_nsleep_restart);
830	return ret;
831}
832
833const struct k_clock alarm_clock = {
834	.clock_getres		= alarm_clock_getres,
835	.clock_get_ktime	= alarm_clock_get_ktime,
836	.clock_get_timespec	= alarm_clock_get_timespec,
837	.timer_create		= alarm_timer_create,
838	.timer_set		= common_timer_set,
839	.timer_del		= common_timer_del,
840	.timer_get		= common_timer_get,
841	.timer_arm		= alarm_timer_arm,
842	.timer_rearm		= alarm_timer_rearm,
843	.timer_forward		= alarm_timer_forward,
844	.timer_remaining	= alarm_timer_remaining,
845	.timer_try_to_cancel	= alarm_timer_try_to_cancel,
846	.timer_wait_running	= alarm_timer_wait_running,
847	.nsleep			= alarm_timer_nsleep,
848};
849#endif /* CONFIG_POSIX_TIMERS */
850
851
852/* Suspend hook structures */
853static const struct dev_pm_ops alarmtimer_pm_ops = {
854	.suspend = alarmtimer_suspend,
855	.resume = alarmtimer_resume,
856};
857
858static struct platform_driver alarmtimer_driver = {
859	.driver = {
860		.name = "alarmtimer",
861		.pm = &alarmtimer_pm_ops,
862	}
863};
864
865static void get_boottime_timespec(struct timespec64 *tp)
866{
867	ktime_get_boottime_ts64(tp);
868	timens_add_boottime(tp);
869}
870
871/**
872 * alarmtimer_init - Initialize alarm timer code
873 *
874 * This function initializes the alarm bases and registers
875 * the posix clock ids.
876 */
877static int __init alarmtimer_init(void)
878{
879	int error;
880	int i;
881
882	alarmtimer_rtc_timer_init();
883
884	/* Initialize alarm bases */
885	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
886	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
887	alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
888	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
889	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
890	alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
891	for (i = 0; i < ALARM_NUMTYPE; i++) {
892		timerqueue_init_head(&alarm_bases[i].timerqueue);
893		spin_lock_init(&alarm_bases[i].lock);
894	}
895
896	error = alarmtimer_rtc_interface_setup();
897	if (error)
898		return error;
899
900	error = platform_driver_register(&alarmtimer_driver);
901	if (error)
902		goto out_if;
903
904	return 0;
905out_if:
906	alarmtimer_rtc_interface_remove();
907	return error;
908}
909device_initcall(alarmtimer_init);