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  */
44 static 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 */
54 static enum alarmtimer_type freezer_alarmtype;
55 static ktime_t freezer_expires;
56 static ktime_t freezer_delta;
57 static DEFINE_SPINLOCK(freezer_delta_lock);
58 #endif
59 
60 #ifdef CONFIG_RTC_CLASS
61 /* rtc timer and device for setting alarm wakeups at suspend */
62 static struct rtc_timer		rtctimer;
63 static struct rtc_device	*rtcdev;
64 static 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  */
alarmtimer_get_rtcdev(void)71 struct 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 }
82 EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
83 
alarmtimer_rtc_add_device(struct device * dev,struct class_interface * class_intf)84 static 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 	}
119 unlock:
120 	spin_unlock_irqrestore(&rtcdev_lock, flags);
121 
122 	platform_device_unregister(pdev);
123 
124 	return ret;
125 }
126 
alarmtimer_rtc_timer_init(void)127 static inline void alarmtimer_rtc_timer_init(void)
128 {
129 	rtc_timer_init(&rtctimer, NULL, NULL);
130 }
131 
132 static struct class_interface alarmtimer_rtc_interface = {
133 	.add_dev = &alarmtimer_rtc_add_device,
134 };
135 
alarmtimer_rtc_interface_setup(void)136 static int alarmtimer_rtc_interface_setup(void)
137 {
138 	alarmtimer_rtc_interface.class = rtc_class;
139 	return class_interface_register(&alarmtimer_rtc_interface);
140 }
alarmtimer_rtc_interface_remove(void)141 static void alarmtimer_rtc_interface_remove(void)
142 {
143 	class_interface_unregister(&alarmtimer_rtc_interface);
144 }
145 #else
alarmtimer_rtc_interface_setup(void)146 static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
alarmtimer_rtc_interface_remove(void)147 static inline void alarmtimer_rtc_interface_remove(void) { }
alarmtimer_rtc_timer_init(void)148 static 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  */
alarmtimer_enqueue(struct alarm_base * base,struct alarm * alarm)160 static 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  */
alarmtimer_dequeue(struct alarm_base * base,struct alarm * alarm)178 static 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  */
alarmtimer_fired(struct hrtimer * timer)197 static 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 
alarm_expires_remaining(const struct alarm * alarm)225 ktime_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 }
230 EXPORT_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  */
alarmtimer_suspend(struct device * dev)242 static 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 
alarmtimer_resume(struct device * dev)303 static 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
alarmtimer_suspend(struct device * dev)314 static int alarmtimer_suspend(struct device *dev)
315 {
316 	return 0;
317 }
318 
alarmtimer_resume(struct device * dev)319 static int alarmtimer_resume(struct device *dev)
320 {
321 	return 0;
322 }
323 #endif
324 
325 static void
__alarm_init(struct alarm * alarm,enum alarmtimer_type type,enum alarmtimer_restart (* function)(struct alarm *,ktime_t))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  */
alarm_init(struct alarm * alarm,enum alarmtimer_type type,enum alarmtimer_restart (* function)(struct alarm *,ktime_t))342 void 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 }
349 EXPORT_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  */
alarm_start(struct alarm * alarm,ktime_t start)356 void 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 }
369 EXPORT_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  */
alarm_start_relative(struct alarm * alarm,ktime_t start)376 void 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 }
383 EXPORT_SYMBOL_GPL(alarm_start_relative);
384 
alarm_restart(struct alarm * alarm)385 void 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 }
396 EXPORT_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  */
alarm_try_to_cancel(struct alarm * alarm)405 int 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 }
420 EXPORT_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  */
alarm_cancel(struct alarm * alarm)429 int 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 }
438 EXPORT_SYMBOL_GPL(alarm_cancel);
439 
440 
alarm_forward(struct alarm * alarm,ktime_t now,ktime_t interval)441 u64 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 }
471 EXPORT_SYMBOL_GPL(alarm_forward);
472 
alarm_forward_now(struct alarm * alarm,ktime_t interval)473 u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
474 {
475 	struct alarm_base *base = &alarm_bases[alarm->type];
476 
477 	return alarm_forward(alarm, base->get_ktime(), interval);
478 }
479 EXPORT_SYMBOL_GPL(alarm_forward_now);
480 
481 #ifdef CONFIG_POSIX_TIMERS
482 
alarmtimer_freezerset(ktime_t absexp,enum alarmtimer_type type)483 static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
484 {
485 	struct alarm_base *base;
486 	unsigned long flags;
487 	ktime_t delta;
488 
489 	switch(type) {
490 	case ALARM_REALTIME:
491 		base = &alarm_bases[ALARM_REALTIME];
492 		type = ALARM_REALTIME_FREEZER;
493 		break;
494 	case ALARM_BOOTTIME:
495 		base = &alarm_bases[ALARM_BOOTTIME];
496 		type = ALARM_BOOTTIME_FREEZER;
497 		break;
498 	default:
499 		WARN_ONCE(1, "Invalid alarm type: %d\n", type);
500 		return;
501 	}
502 
503 	delta = ktime_sub(absexp, base->get_ktime());
504 
505 	spin_lock_irqsave(&freezer_delta_lock, flags);
506 	if (!freezer_delta || (delta < freezer_delta)) {
507 		freezer_delta = delta;
508 		freezer_expires = absexp;
509 		freezer_alarmtype = type;
510 	}
511 	spin_unlock_irqrestore(&freezer_delta_lock, flags);
512 }
513 
514 /**
515  * clock2alarm - helper that converts from clockid to alarmtypes
516  * @clockid: clockid.
517  */
clock2alarm(clockid_t clockid)518 static enum alarmtimer_type clock2alarm(clockid_t clockid)
519 {
520 	if (clockid == CLOCK_REALTIME_ALARM)
521 		return ALARM_REALTIME;
522 	if (clockid == CLOCK_BOOTTIME_ALARM)
523 		return ALARM_BOOTTIME;
524 	return -1;
525 }
526 
527 /**
528  * alarm_handle_timer - Callback for posix timers
529  * @alarm: alarm that fired
530  * @now: time at the timer expiration
531  *
532  * Posix timer callback for expired alarm timers.
533  *
534  * Return: whether the timer is to be restarted
535  */
alarm_handle_timer(struct alarm * alarm,ktime_t now)536 static enum alarmtimer_restart alarm_handle_timer(struct alarm *alarm,
537 							ktime_t now)
538 {
539 	struct k_itimer *ptr = container_of(alarm, struct k_itimer,
540 					    it.alarm.alarmtimer);
541 	enum alarmtimer_restart result = ALARMTIMER_NORESTART;
542 	unsigned long flags;
543 	int si_private = 0;
544 
545 	spin_lock_irqsave(&ptr->it_lock, flags);
546 
547 	ptr->it_active = 0;
548 	if (ptr->it_interval)
549 		si_private = ++ptr->it_requeue_pending;
550 
551 	if (posix_timer_event(ptr, si_private) && ptr->it_interval) {
552 		/*
553 		 * Handle ignored signals and rearm the timer. This will go
554 		 * away once we handle ignored signals proper.
555 		 */
556 		ptr->it_overrun += alarm_forward_now(alarm, ptr->it_interval);
557 		++ptr->it_requeue_pending;
558 		ptr->it_active = 1;
559 		result = ALARMTIMER_RESTART;
560 	}
561 	spin_unlock_irqrestore(&ptr->it_lock, flags);
562 
563 	return result;
564 }
565 
566 /**
567  * alarm_timer_rearm - Posix timer callback for rearming timer
568  * @timr:	Pointer to the posixtimer data struct
569  */
alarm_timer_rearm(struct k_itimer * timr)570 static void alarm_timer_rearm(struct k_itimer *timr)
571 {
572 	struct alarm *alarm = &timr->it.alarm.alarmtimer;
573 
574 	timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
575 	alarm_start(alarm, alarm->node.expires);
576 }
577 
578 /**
579  * alarm_timer_forward - Posix timer callback for forwarding timer
580  * @timr:	Pointer to the posixtimer data struct
581  * @now:	Current time to forward the timer against
582  */
alarm_timer_forward(struct k_itimer * timr,ktime_t now)583 static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
584 {
585 	struct alarm *alarm = &timr->it.alarm.alarmtimer;
586 
587 	return alarm_forward(alarm, timr->it_interval, now);
588 }
589 
590 /**
591  * alarm_timer_remaining - Posix timer callback to retrieve remaining time
592  * @timr:	Pointer to the posixtimer data struct
593  * @now:	Current time to calculate against
594  */
alarm_timer_remaining(struct k_itimer * timr,ktime_t now)595 static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
596 {
597 	struct alarm *alarm = &timr->it.alarm.alarmtimer;
598 
599 	return ktime_sub(alarm->node.expires, now);
600 }
601 
602 /**
603  * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
604  * @timr:	Pointer to the posixtimer data struct
605  */
alarm_timer_try_to_cancel(struct k_itimer * timr)606 static int alarm_timer_try_to_cancel(struct k_itimer *timr)
607 {
608 	return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
609 }
610 
611 /**
612  * alarm_timer_wait_running - Posix timer callback to wait for a timer
613  * @timr:	Pointer to the posixtimer data struct
614  *
615  * Called from the core code when timer cancel detected that the callback
616  * is running. @timr is unlocked and rcu read lock is held to prevent it
617  * from being freed.
618  */
alarm_timer_wait_running(struct k_itimer * timr)619 static void alarm_timer_wait_running(struct k_itimer *timr)
620 {
621 	hrtimer_cancel_wait_running(&timr->it.alarm.alarmtimer.timer);
622 }
623 
624 /**
625  * alarm_timer_arm - Posix timer callback to arm a timer
626  * @timr:	Pointer to the posixtimer data struct
627  * @expires:	The new expiry time
628  * @absolute:	Expiry value is absolute time
629  * @sigev_none:	Posix timer does not deliver signals
630  */
alarm_timer_arm(struct k_itimer * timr,ktime_t expires,bool absolute,bool sigev_none)631 static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
632 			    bool absolute, bool sigev_none)
633 {
634 	struct alarm *alarm = &timr->it.alarm.alarmtimer;
635 	struct alarm_base *base = &alarm_bases[alarm->type];
636 
637 	if (!absolute)
638 		expires = ktime_add_safe(expires, base->get_ktime());
639 	if (sigev_none)
640 		alarm->node.expires = expires;
641 	else
642 		alarm_start(&timr->it.alarm.alarmtimer, expires);
643 }
644 
645 /**
646  * alarm_clock_getres - posix getres interface
647  * @which_clock: clockid
648  * @tp: timespec to fill
649  *
650  * Returns the granularity of underlying alarm base clock
651  */
alarm_clock_getres(const clockid_t which_clock,struct timespec64 * tp)652 static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
653 {
654 	if (!alarmtimer_get_rtcdev())
655 		return -EINVAL;
656 
657 	tp->tv_sec = 0;
658 	tp->tv_nsec = hrtimer_resolution;
659 	return 0;
660 }
661 
662 /**
663  * alarm_clock_get_timespec - posix clock_get_timespec interface
664  * @which_clock: clockid
665  * @tp: timespec to fill.
666  *
667  * Provides the underlying alarm base time in a tasks time namespace.
668  */
alarm_clock_get_timespec(clockid_t which_clock,struct timespec64 * tp)669 static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
670 {
671 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
672 
673 	if (!alarmtimer_get_rtcdev())
674 		return -EINVAL;
675 
676 	base->get_timespec(tp);
677 
678 	return 0;
679 }
680 
681 /**
682  * alarm_clock_get_ktime - posix clock_get_ktime interface
683  * @which_clock: clockid
684  *
685  * Provides the underlying alarm base time in the root namespace.
686  */
alarm_clock_get_ktime(clockid_t which_clock)687 static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
688 {
689 	struct alarm_base *base = &alarm_bases[clock2alarm(which_clock)];
690 
691 	if (!alarmtimer_get_rtcdev())
692 		return -EINVAL;
693 
694 	return base->get_ktime();
695 }
696 
697 /**
698  * alarm_timer_create - posix timer_create interface
699  * @new_timer: k_itimer pointer to manage
700  *
701  * Initializes the k_itimer structure.
702  */
alarm_timer_create(struct k_itimer * new_timer)703 static int alarm_timer_create(struct k_itimer *new_timer)
704 {
705 	enum  alarmtimer_type type;
706 
707 	if (!alarmtimer_get_rtcdev())
708 		return -EOPNOTSUPP;
709 
710 	if (!capable(CAP_WAKE_ALARM))
711 		return -EPERM;
712 
713 	type = clock2alarm(new_timer->it_clock);
714 	alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
715 	return 0;
716 }
717 
718 /**
719  * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
720  * @alarm: ptr to alarm that fired
721  * @now: time at the timer expiration
722  *
723  * Wakes up the task that set the alarmtimer
724  *
725  * Return: ALARMTIMER_NORESTART
726  */
alarmtimer_nsleep_wakeup(struct alarm * alarm,ktime_t now)727 static enum alarmtimer_restart alarmtimer_nsleep_wakeup(struct alarm *alarm,
728 								ktime_t now)
729 {
730 	struct task_struct *task = (struct task_struct *)alarm->data;
731 
732 	alarm->data = NULL;
733 	if (task)
734 		wake_up_process(task);
735 	return ALARMTIMER_NORESTART;
736 }
737 
738 /**
739  * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
740  * @alarm: ptr to alarmtimer
741  * @absexp: absolute expiration time
742  * @type: alarm type (BOOTTIME/REALTIME).
743  *
744  * Sets the alarm timer and sleeps until it is fired or interrupted.
745  */
alarmtimer_do_nsleep(struct alarm * alarm,ktime_t absexp,enum alarmtimer_type type)746 static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
747 				enum alarmtimer_type type)
748 {
749 	struct restart_block *restart;
750 	alarm->data = (void *)current;
751 	do {
752 		set_current_state(TASK_INTERRUPTIBLE);
753 		alarm_start(alarm, absexp);
754 		if (likely(alarm->data))
755 			schedule();
756 
757 		alarm_cancel(alarm);
758 	} while (alarm->data && !signal_pending(current));
759 
760 	__set_current_state(TASK_RUNNING);
761 
762 	destroy_hrtimer_on_stack(&alarm->timer);
763 
764 	if (!alarm->data)
765 		return 0;
766 
767 	if (freezing(current))
768 		alarmtimer_freezerset(absexp, type);
769 	restart = &current->restart_block;
770 	if (restart->nanosleep.type != TT_NONE) {
771 		struct timespec64 rmt;
772 		ktime_t rem;
773 
774 		rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
775 
776 		if (rem <= 0)
777 			return 0;
778 		rmt = ktime_to_timespec64(rem);
779 
780 		return nanosleep_copyout(restart, &rmt);
781 	}
782 	return -ERESTART_RESTARTBLOCK;
783 }
784 
785 static void
alarm_init_on_stack(struct alarm * alarm,enum alarmtimer_type type,enum alarmtimer_restart (* function)(struct alarm *,ktime_t))786 alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
787 		    enum alarmtimer_restart (*function)(struct alarm *, ktime_t))
788 {
789 	hrtimer_init_on_stack(&alarm->timer, alarm_bases[type].base_clockid,
790 			      HRTIMER_MODE_ABS);
791 	__alarm_init(alarm, type, function);
792 }
793 
794 /**
795  * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
796  * @restart: ptr to restart block
797  *
798  * Handles restarted clock_nanosleep calls
799  */
alarm_timer_nsleep_restart(struct restart_block * restart)800 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
801 {
802 	enum  alarmtimer_type type = restart->nanosleep.clockid;
803 	ktime_t exp = restart->nanosleep.expires;
804 	struct alarm alarm;
805 
806 	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
807 
808 	return alarmtimer_do_nsleep(&alarm, exp, type);
809 }
810 
811 /**
812  * alarm_timer_nsleep - alarmtimer nanosleep
813  * @which_clock: clockid
814  * @flags: determines abstime or relative
815  * @tsreq: requested sleep time (abs or rel)
816  *
817  * Handles clock_nanosleep calls against _ALARM clockids
818  */
alarm_timer_nsleep(const clockid_t which_clock,int flags,const struct timespec64 * tsreq)819 static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
820 			      const struct timespec64 *tsreq)
821 {
822 	enum  alarmtimer_type type = clock2alarm(which_clock);
823 	struct restart_block *restart = &current->restart_block;
824 	struct alarm alarm;
825 	ktime_t exp;
826 	int ret = 0;
827 
828 	if (!alarmtimer_get_rtcdev())
829 		return -EOPNOTSUPP;
830 
831 	if (flags & ~TIMER_ABSTIME)
832 		return -EINVAL;
833 
834 	if (!capable(CAP_WAKE_ALARM))
835 		return -EPERM;
836 
837 	alarm_init_on_stack(&alarm, type, alarmtimer_nsleep_wakeup);
838 
839 	exp = timespec64_to_ktime(*tsreq);
840 	/* Convert (if necessary) to absolute time */
841 	if (flags != TIMER_ABSTIME) {
842 		ktime_t now = alarm_bases[type].get_ktime();
843 
844 		exp = ktime_add_safe(now, exp);
845 	} else {
846 		exp = timens_ktime_to_host(which_clock, exp);
847 	}
848 
849 	ret = alarmtimer_do_nsleep(&alarm, exp, type);
850 	if (ret != -ERESTART_RESTARTBLOCK)
851 		return ret;
852 
853 	/* abs timers don't set remaining time or restart */
854 	if (flags == TIMER_ABSTIME)
855 		return -ERESTARTNOHAND;
856 
857 	restart->nanosleep.clockid = type;
858 	restart->nanosleep.expires = exp;
859 	set_restart_fn(restart, alarm_timer_nsleep_restart);
860 	return ret;
861 }
862 
863 const struct k_clock alarm_clock = {
864 	.clock_getres		= alarm_clock_getres,
865 	.clock_get_ktime	= alarm_clock_get_ktime,
866 	.clock_get_timespec	= alarm_clock_get_timespec,
867 	.timer_create		= alarm_timer_create,
868 	.timer_set		= common_timer_set,
869 	.timer_del		= common_timer_del,
870 	.timer_get		= common_timer_get,
871 	.timer_arm		= alarm_timer_arm,
872 	.timer_rearm		= alarm_timer_rearm,
873 	.timer_forward		= alarm_timer_forward,
874 	.timer_remaining	= alarm_timer_remaining,
875 	.timer_try_to_cancel	= alarm_timer_try_to_cancel,
876 	.timer_wait_running	= alarm_timer_wait_running,
877 	.nsleep			= alarm_timer_nsleep,
878 };
879 #endif /* CONFIG_POSIX_TIMERS */
880 
881 
882 /* Suspend hook structures */
883 static const struct dev_pm_ops alarmtimer_pm_ops = {
884 	.suspend = alarmtimer_suspend,
885 	.resume = alarmtimer_resume,
886 };
887 
888 static struct platform_driver alarmtimer_driver = {
889 	.driver = {
890 		.name = "alarmtimer",
891 		.pm = &alarmtimer_pm_ops,
892 	}
893 };
894 
get_boottime_timespec(struct timespec64 * tp)895 static void get_boottime_timespec(struct timespec64 *tp)
896 {
897 	ktime_get_boottime_ts64(tp);
898 	timens_add_boottime(tp);
899 }
900 
901 /**
902  * alarmtimer_init - Initialize alarm timer code
903  *
904  * This function initializes the alarm bases and registers
905  * the posix clock ids.
906  */
alarmtimer_init(void)907 static int __init alarmtimer_init(void)
908 {
909 	int error;
910 	int i;
911 
912 	alarmtimer_rtc_timer_init();
913 
914 	/* Initialize alarm bases */
915 	alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
916 	alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
917 	alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
918 	alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
919 	alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
920 	alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
921 	for (i = 0; i < ALARM_NUMTYPE; i++) {
922 		timerqueue_init_head(&alarm_bases[i].timerqueue);
923 		spin_lock_init(&alarm_bases[i].lock);
924 	}
925 
926 	error = alarmtimer_rtc_interface_setup();
927 	if (error)
928 		return error;
929 
930 	error = platform_driver_register(&alarmtimer_driver);
931 	if (error)
932 		goto out_if;
933 
934 	return 0;
935 out_if:
936 	alarmtimer_rtc_interface_remove();
937 	return error;
938 }
939 device_initcall(alarmtimer_init);
940