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 = &current->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 = &current->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);