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 struct rtc_device *ret;
74
75 guard(spinlock_irqsave)(l: &rtcdev_lock);
76 ret = rtcdev;
77
78 return ret;
79}
80EXPORT_SYMBOL_GPL(alarmtimer_get_rtcdev);
81
82static int alarmtimer_rtc_add_device(struct device *dev)
83{
84 struct rtc_device *rtc = to_rtc_device(dev);
85 struct platform_device *pdev;
86 int ret = 0;
87
88 if (rtcdev)
89 return -EBUSY;
90
91 if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
92 return -1;
93 if (!device_may_wakeup(dev: rtc->dev.parent))
94 return -1;
95
96 pdev = platform_device_register_data(parent: dev, name: "alarmtimer",
97 PLATFORM_DEVID_AUTO, NULL, size: 0);
98 if (!IS_ERR(ptr: pdev))
99 device_init_wakeup(dev: &pdev->dev, enable: true);
100
101 scoped_guard(spinlock_irqsave, &rtcdev_lock) {
102 if (!IS_ERR(ptr: pdev) && !rtcdev && try_module_get(module: rtc->owner)) {
103 rtcdev = rtc;
104 /* hold a reference so it doesn't go away */
105 get_device(dev);
106 pdev = NULL;
107 } else {
108 ret = -1;
109 }
110 }
111
112 platform_device_unregister(pdev);
113 return ret;
114}
115
116static inline void alarmtimer_rtc_timer_init(void)
117{
118 rtc_timer_init(timer: &rtctimer, NULL, NULL);
119}
120
121static struct class_interface alarmtimer_rtc_interface = {
122 .add_dev = &alarmtimer_rtc_add_device,
123};
124
125static int alarmtimer_rtc_interface_setup(void)
126{
127 alarmtimer_rtc_interface.class = &rtc_class;
128 return class_interface_register(&alarmtimer_rtc_interface);
129}
130static void alarmtimer_rtc_interface_remove(void)
131{
132 class_interface_unregister(&alarmtimer_rtc_interface);
133}
134#else
135static inline int alarmtimer_rtc_interface_setup(void) { return 0; }
136static inline void alarmtimer_rtc_interface_remove(void) { }
137static inline void alarmtimer_rtc_timer_init(void) { }
138#endif
139
140/**
141 * alarmtimer_enqueue - Adds an alarm timer to an alarm_base timerqueue
142 * @base: pointer to the base where the timer is being run
143 * @alarm: pointer to alarm being enqueued.
144 *
145 * Adds alarm to a alarm_base timerqueue
146 *
147 * Must hold base->lock when calling.
148 */
149static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm)
150{
151 if (alarm->state & ALARMTIMER_STATE_ENQUEUED)
152 timerqueue_del(head: &base->timerqueue, node: &alarm->node);
153
154 timerqueue_add(head: &base->timerqueue, node: &alarm->node);
155 alarm->state |= ALARMTIMER_STATE_ENQUEUED;
156}
157
158/**
159 * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue
160 * @base: pointer to the base where the timer is running
161 * @alarm: pointer to alarm being removed
162 *
163 * Removes alarm to a alarm_base timerqueue
164 *
165 * Must hold base->lock when calling.
166 */
167static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm)
168{
169 if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED))
170 return;
171
172 timerqueue_del(head: &base->timerqueue, node: &alarm->node);
173 alarm->state &= ~ALARMTIMER_STATE_ENQUEUED;
174}
175
176
177/**
178 * alarmtimer_fired - Handles alarm hrtimer being fired.
179 * @timer: pointer to hrtimer being run
180 *
181 * When a alarm timer fires, this runs through the timerqueue to
182 * see which alarms expired, and runs those. If there are more alarm
183 * timers queued for the future, we set the hrtimer to fire when
184 * the next future alarm timer expires.
185 */
186static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)
187{
188 struct alarm *alarm = container_of(timer, struct alarm, timer);
189 struct alarm_base *base = &alarm_bases[alarm->type];
190
191 scoped_guard(spinlock_irqsave, &base->lock)
192 alarmtimer_dequeue(base, alarm);
193
194 if (alarm->function)
195 alarm->function(alarm, base->get_ktime());
196
197 trace_alarmtimer_fired(alarm, now: base->get_ktime());
198 return HRTIMER_NORESTART;
199}
200
201ktime_t alarm_expires_remaining(const struct alarm *alarm)
202{
203 struct alarm_base *base = &alarm_bases[alarm->type];
204 return ktime_sub(alarm->node.expires, base->get_ktime());
205}
206EXPORT_SYMBOL_GPL(alarm_expires_remaining);
207
208#ifdef CONFIG_RTC_CLASS
209/**
210 * alarmtimer_suspend - Suspend time callback
211 * @dev: unused
212 *
213 * When we are going into suspend, we look through the bases
214 * to see which is the soonest timer to expire. We then
215 * set an rtc timer to fire that far into the future, which
216 * will wake us from suspend.
217 */
218static int alarmtimer_suspend(struct device *dev)
219{
220 ktime_t min, now, expires;
221 struct rtc_device *rtc;
222 struct rtc_time tm;
223 int i, ret, type;
224
225 scoped_guard(spinlock_irqsave, &freezer_delta_lock) {
226 min = freezer_delta;
227 expires = freezer_expires;
228 type = freezer_alarmtype;
229 freezer_delta = 0;
230 }
231
232 rtc = alarmtimer_get_rtcdev();
233 /* If we have no rtcdev, just return */
234 if (!rtc)
235 return 0;
236
237 /* Find the soonest timer to expire*/
238 for (i = 0; i < ALARM_NUMTYPE; i++) {
239 struct alarm_base *base = &alarm_bases[i];
240 struct timerqueue_node *next;
241 ktime_t delta;
242
243 scoped_guard(spinlock_irqsave, &base->lock)
244 next = timerqueue_getnext(head: &base->timerqueue);
245 if (!next)
246 continue;
247 delta = ktime_sub(next->expires, base->get_ktime());
248 if (!min || (delta < min)) {
249 expires = next->expires;
250 min = delta;
251 type = i;
252 }
253 }
254 if (min == 0)
255 return 0;
256
257 if (ktime_to_ns(kt: min) < 2 * NSEC_PER_SEC) {
258 pm_wakeup_event(dev, msec: 2 * MSEC_PER_SEC);
259 return -EBUSY;
260 }
261
262 trace_alarmtimer_suspend(expires, flag: type);
263
264 /* Setup an rtc timer to fire that far in the future */
265 rtc_timer_cancel(rtc, timer: &rtctimer);
266 rtc_read_time(rtc, tm: &tm);
267 now = rtc_tm_to_ktime(tm);
268
269 /*
270 * If the RTC alarm timer only supports a limited time offset, set the
271 * alarm time to the maximum supported value.
272 * The system may wake up earlier (possibly much earlier) than expected
273 * when the alarmtimer runs. This is the best the kernel can do if
274 * the alarmtimer exceeds the time that the rtc device can be programmed
275 * for.
276 */
277 min = rtc_bound_alarmtime(rtc, requested: min);
278
279 now = ktime_add(now, min);
280
281 /* Set alarm, if in the past reject suspend briefly to handle */
282 ret = rtc_timer_start(rtc, timer: &rtctimer, expires: now, period: 0);
283 if (ret < 0)
284 pm_wakeup_event(dev, MSEC_PER_SEC);
285 return ret;
286}
287
288static int alarmtimer_resume(struct device *dev)
289{
290 struct rtc_device *rtc;
291
292 rtc = alarmtimer_get_rtcdev();
293 if (rtc)
294 rtc_timer_cancel(rtc, timer: &rtctimer);
295 return 0;
296}
297
298#else
299static int alarmtimer_suspend(struct device *dev)
300{
301 return 0;
302}
303
304static int alarmtimer_resume(struct device *dev)
305{
306 return 0;
307}
308#endif
309
310static void
311__alarm_init(struct alarm *alarm, enum alarmtimer_type type,
312 void (*function)(struct alarm *, ktime_t))
313{
314 timerqueue_init(node: &alarm->node);
315 alarm->function = function;
316 alarm->type = type;
317 alarm->state = ALARMTIMER_STATE_INACTIVE;
318}
319
320/**
321 * alarm_init - Initialize an alarm structure
322 * @alarm: ptr to alarm to be initialized
323 * @type: the type of the alarm
324 * @function: callback that is run when the alarm fires
325 */
326void alarm_init(struct alarm *alarm, enum alarmtimer_type type,
327 void (*function)(struct alarm *, ktime_t))
328{
329 hrtimer_setup(timer: &alarm->timer, function: alarmtimer_fired, clock_id: alarm_bases[type].base_clockid,
330 mode: HRTIMER_MODE_ABS);
331 __alarm_init(alarm, type, function);
332}
333EXPORT_SYMBOL_GPL(alarm_init);
334
335/**
336 * alarm_start - Sets an absolute alarm to fire
337 * @alarm: ptr to alarm to set
338 * @start: time to run the alarm
339 */
340void alarm_start(struct alarm *alarm, ktime_t start)
341{
342 struct alarm_base *base = &alarm_bases[alarm->type];
343
344 scoped_guard(spinlock_irqsave, &base->lock) {
345 alarm->node.expires = start;
346 alarmtimer_enqueue(base, alarm);
347 hrtimer_start(timer: &alarm->timer, tim: alarm->node.expires, mode: HRTIMER_MODE_ABS);
348 }
349
350 trace_alarmtimer_start(alarm, now: base->get_ktime());
351}
352EXPORT_SYMBOL_GPL(alarm_start);
353
354/**
355 * alarm_start_relative - Sets a relative alarm to fire
356 * @alarm: ptr to alarm to set
357 * @start: time relative to now to run the alarm
358 */
359void alarm_start_relative(struct alarm *alarm, ktime_t start)
360{
361 struct alarm_base *base = &alarm_bases[alarm->type];
362
363 start = ktime_add_safe(lhs: start, rhs: base->get_ktime());
364 alarm_start(alarm, start);
365}
366EXPORT_SYMBOL_GPL(alarm_start_relative);
367
368void alarm_restart(struct alarm *alarm)
369{
370 struct alarm_base *base = &alarm_bases[alarm->type];
371
372 guard(spinlock_irqsave)(l: &base->lock);
373 hrtimer_set_expires(timer: &alarm->timer, time: alarm->node.expires);
374 hrtimer_restart(timer: &alarm->timer);
375 alarmtimer_enqueue(base, alarm);
376}
377EXPORT_SYMBOL_GPL(alarm_restart);
378
379/**
380 * alarm_try_to_cancel - Tries to cancel an alarm timer
381 * @alarm: ptr to alarm to be canceled
382 *
383 * Returns 1 if the timer was canceled, 0 if it was not running,
384 * and -1 if the callback was running
385 */
386int alarm_try_to_cancel(struct alarm *alarm)
387{
388 struct alarm_base *base = &alarm_bases[alarm->type];
389 int ret;
390
391 scoped_guard(spinlock_irqsave, &base->lock) {
392 ret = hrtimer_try_to_cancel(timer: &alarm->timer);
393 if (ret >= 0)
394 alarmtimer_dequeue(base, alarm);
395 }
396
397 trace_alarmtimer_cancel(alarm, now: base->get_ktime());
398 return ret;
399}
400EXPORT_SYMBOL_GPL(alarm_try_to_cancel);
401
402
403/**
404 * alarm_cancel - Spins trying to cancel an alarm timer until it is done
405 * @alarm: ptr to alarm to be canceled
406 *
407 * Returns 1 if the timer was canceled, 0 if it was not active.
408 */
409int alarm_cancel(struct alarm *alarm)
410{
411 for (;;) {
412 int ret = alarm_try_to_cancel(alarm);
413 if (ret >= 0)
414 return ret;
415 hrtimer_cancel_wait_running(timer: &alarm->timer);
416 }
417}
418EXPORT_SYMBOL_GPL(alarm_cancel);
419
420
421u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval)
422{
423 u64 overrun = 1;
424 ktime_t delta;
425
426 delta = ktime_sub(now, alarm->node.expires);
427
428 if (delta < 0)
429 return 0;
430
431 if (unlikely(delta >= interval)) {
432 s64 incr = ktime_to_ns(kt: interval);
433
434 overrun = ktime_divns(kt: delta, div: incr);
435
436 alarm->node.expires = ktime_add_ns(alarm->node.expires,
437 incr*overrun);
438
439 if (alarm->node.expires > now)
440 return overrun;
441 /*
442 * This (and the ktime_add() below) is the
443 * correction for exact:
444 */
445 overrun++;
446 }
447
448 alarm->node.expires = ktime_add_safe(lhs: alarm->node.expires, rhs: interval);
449 return overrun;
450}
451EXPORT_SYMBOL_GPL(alarm_forward);
452
453u64 alarm_forward_now(struct alarm *alarm, ktime_t interval)
454{
455 struct alarm_base *base = &alarm_bases[alarm->type];
456
457 return alarm_forward(alarm, base->get_ktime(), interval);
458}
459EXPORT_SYMBOL_GPL(alarm_forward_now);
460
461#ifdef CONFIG_POSIX_TIMERS
462
463static void alarmtimer_freezerset(ktime_t absexp, enum alarmtimer_type type)
464{
465 struct alarm_base *base;
466 ktime_t delta;
467
468 switch(type) {
469 case ALARM_REALTIME:
470 base = &alarm_bases[ALARM_REALTIME];
471 type = ALARM_REALTIME_FREEZER;
472 break;
473 case ALARM_BOOTTIME:
474 base = &alarm_bases[ALARM_BOOTTIME];
475 type = ALARM_BOOTTIME_FREEZER;
476 break;
477 default:
478 WARN_ONCE(1, "Invalid alarm type: %d\n", type);
479 return;
480 }
481
482 delta = ktime_sub(absexp, base->get_ktime());
483
484 guard(spinlock_irqsave)(l: &freezer_delta_lock);
485 if (!freezer_delta || (delta < freezer_delta)) {
486 freezer_delta = delta;
487 freezer_expires = absexp;
488 freezer_alarmtype = type;
489 }
490}
491
492/**
493 * clock2alarm - helper that converts from clockid to alarmtypes
494 * @clockid: clockid.
495 */
496static enum alarmtimer_type clock2alarm(clockid_t clockid)
497{
498 if (clockid == CLOCK_REALTIME_ALARM)
499 return ALARM_REALTIME;
500
501 WARN_ON_ONCE(clockid != CLOCK_BOOTTIME_ALARM);
502 return ALARM_BOOTTIME;
503}
504
505/**
506 * alarm_handle_timer - Callback for posix timers
507 * @alarm: alarm that fired
508 * @now: time at the timer expiration
509 *
510 * Posix timer callback for expired alarm timers.
511 *
512 * Return: whether the timer is to be restarted
513 */
514static void alarm_handle_timer(struct alarm *alarm, ktime_t now)
515{
516 struct k_itimer *ptr = container_of(alarm, struct k_itimer, it.alarm.alarmtimer);
517
518 guard(spinlock_irqsave)(l: &ptr->it_lock);
519 posix_timer_queue_signal(timr: ptr);
520}
521
522/**
523 * alarm_timer_rearm - Posix timer callback for rearming timer
524 * @timr: Pointer to the posixtimer data struct
525 */
526static void alarm_timer_rearm(struct k_itimer *timr)
527{
528 struct alarm *alarm = &timr->it.alarm.alarmtimer;
529
530 timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
531 alarm_start(alarm, alarm->node.expires);
532}
533
534/**
535 * alarm_timer_forward - Posix timer callback for forwarding timer
536 * @timr: Pointer to the posixtimer data struct
537 * @now: Current time to forward the timer against
538 */
539static s64 alarm_timer_forward(struct k_itimer *timr, ktime_t now)
540{
541 struct alarm *alarm = &timr->it.alarm.alarmtimer;
542
543 return alarm_forward(alarm, timr->it_interval, now);
544}
545
546/**
547 * alarm_timer_remaining - Posix timer callback to retrieve remaining time
548 * @timr: Pointer to the posixtimer data struct
549 * @now: Current time to calculate against
550 */
551static ktime_t alarm_timer_remaining(struct k_itimer *timr, ktime_t now)
552{
553 struct alarm *alarm = &timr->it.alarm.alarmtimer;
554
555 return ktime_sub(alarm->node.expires, now);
556}
557
558/**
559 * alarm_timer_try_to_cancel - Posix timer callback to cancel a timer
560 * @timr: Pointer to the posixtimer data struct
561 */
562static int alarm_timer_try_to_cancel(struct k_itimer *timr)
563{
564 return alarm_try_to_cancel(&timr->it.alarm.alarmtimer);
565}
566
567/**
568 * alarm_timer_wait_running - Posix timer callback to wait for a timer
569 * @timr: Pointer to the posixtimer data struct
570 *
571 * Called from the core code when timer cancel detected that the callback
572 * is running. @timr is unlocked and rcu read lock is held to prevent it
573 * from being freed.
574 */
575static void alarm_timer_wait_running(struct k_itimer *timr)
576{
577 hrtimer_cancel_wait_running(timer: &timr->it.alarm.alarmtimer.timer);
578}
579
580/**
581 * alarm_timer_arm - Posix timer callback to arm a timer
582 * @timr: Pointer to the posixtimer data struct
583 * @expires: The new expiry time
584 * @absolute: Expiry value is absolute time
585 * @sigev_none: Posix timer does not deliver signals
586 */
587static void alarm_timer_arm(struct k_itimer *timr, ktime_t expires,
588 bool absolute, bool sigev_none)
589{
590 struct alarm *alarm = &timr->it.alarm.alarmtimer;
591 struct alarm_base *base = &alarm_bases[alarm->type];
592
593 if (!absolute)
594 expires = ktime_add_safe(lhs: expires, rhs: base->get_ktime());
595 if (sigev_none)
596 alarm->node.expires = expires;
597 else
598 alarm_start(&timr->it.alarm.alarmtimer, expires);
599}
600
601/**
602 * alarm_clock_getres - posix getres interface
603 * @which_clock: clockid
604 * @tp: timespec to fill
605 *
606 * Returns the granularity of underlying alarm base clock
607 */
608static int alarm_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
609{
610 if (!alarmtimer_get_rtcdev())
611 return -EINVAL;
612
613 tp->tv_sec = 0;
614 tp->tv_nsec = hrtimer_resolution;
615 return 0;
616}
617
618/**
619 * alarm_clock_get_timespec - posix clock_get_timespec interface
620 * @which_clock: clockid
621 * @tp: timespec to fill.
622 *
623 * Provides the underlying alarm base time in a tasks time namespace.
624 */
625static int alarm_clock_get_timespec(clockid_t which_clock, struct timespec64 *tp)
626{
627 struct alarm_base *base = &alarm_bases[clock2alarm(clockid: which_clock)];
628
629 if (!alarmtimer_get_rtcdev())
630 return -EINVAL;
631
632 base->get_timespec(tp);
633
634 return 0;
635}
636
637/**
638 * alarm_clock_get_ktime - posix clock_get_ktime interface
639 * @which_clock: clockid
640 *
641 * Provides the underlying alarm base time in the root namespace.
642 */
643static ktime_t alarm_clock_get_ktime(clockid_t which_clock)
644{
645 struct alarm_base *base = &alarm_bases[clock2alarm(clockid: which_clock)];
646
647 if (!alarmtimer_get_rtcdev())
648 return -EINVAL;
649
650 return base->get_ktime();
651}
652
653/**
654 * alarm_timer_create - posix timer_create interface
655 * @new_timer: k_itimer pointer to manage
656 *
657 * Initializes the k_itimer structure.
658 */
659static int alarm_timer_create(struct k_itimer *new_timer)
660{
661 enum alarmtimer_type type;
662
663 if (!alarmtimer_get_rtcdev())
664 return -EOPNOTSUPP;
665
666 if (!capable(CAP_WAKE_ALARM))
667 return -EPERM;
668
669 type = clock2alarm(clockid: new_timer->it_clock);
670 alarm_init(&new_timer->it.alarm.alarmtimer, type, alarm_handle_timer);
671 return 0;
672}
673
674/**
675 * alarmtimer_nsleep_wakeup - Wakeup function for alarm_timer_nsleep
676 * @alarm: ptr to alarm that fired
677 * @now: time at the timer expiration
678 *
679 * Wakes up the task that set the alarmtimer
680 */
681static void alarmtimer_nsleep_wakeup(struct alarm *alarm, ktime_t now)
682{
683 struct task_struct *task = alarm->data;
684
685 alarm->data = NULL;
686 if (task)
687 wake_up_process(tsk: task);
688}
689
690/**
691 * alarmtimer_do_nsleep - Internal alarmtimer nsleep implementation
692 * @alarm: ptr to alarmtimer
693 * @absexp: absolute expiration time
694 * @type: alarm type (BOOTTIME/REALTIME).
695 *
696 * Sets the alarm timer and sleeps until it is fired or interrupted.
697 */
698static int alarmtimer_do_nsleep(struct alarm *alarm, ktime_t absexp,
699 enum alarmtimer_type type)
700{
701 struct restart_block *restart;
702 alarm->data = (void *)current;
703 do {
704 set_current_state(TASK_INTERRUPTIBLE);
705 alarm_start(alarm, absexp);
706 if (likely(alarm->data))
707 schedule();
708
709 alarm_cancel(alarm);
710 } while (alarm->data && !signal_pending(current));
711
712 __set_current_state(TASK_RUNNING);
713
714 destroy_hrtimer_on_stack(timer: &alarm->timer);
715
716 if (!alarm->data)
717 return 0;
718
719 if (freezing(current))
720 alarmtimer_freezerset(absexp, type);
721 restart = &current->restart_block;
722 if (restart->nanosleep.type != TT_NONE) {
723 struct timespec64 rmt;
724 ktime_t rem;
725
726 rem = ktime_sub(absexp, alarm_bases[type].get_ktime());
727
728 if (rem <= 0)
729 return 0;
730 rmt = ktime_to_timespec64(rem);
731
732 return nanosleep_copyout(restart, &rmt);
733 }
734 return -ERESTART_RESTARTBLOCK;
735}
736
737static void
738alarm_init_on_stack(struct alarm *alarm, enum alarmtimer_type type,
739 void (*function)(struct alarm *, ktime_t))
740{
741 hrtimer_setup_on_stack(timer: &alarm->timer, function: alarmtimer_fired, clock_id: alarm_bases[type].base_clockid,
742 mode: HRTIMER_MODE_ABS);
743 __alarm_init(alarm, type, function);
744}
745
746/**
747 * alarm_timer_nsleep_restart - restartblock alarmtimer nsleep
748 * @restart: ptr to restart block
749 *
750 * Handles restarted clock_nanosleep calls
751 */
752static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
753{
754 enum alarmtimer_type type = restart->nanosleep.clockid;
755 ktime_t exp = restart->nanosleep.expires;
756 struct alarm alarm;
757
758 alarm_init_on_stack(alarm: &alarm, type, function: alarmtimer_nsleep_wakeup);
759
760 return alarmtimer_do_nsleep(alarm: &alarm, absexp: exp, type);
761}
762
763/**
764 * alarm_timer_nsleep - alarmtimer nanosleep
765 * @which_clock: clockid
766 * @flags: determines abstime or relative
767 * @tsreq: requested sleep time (abs or rel)
768 *
769 * Handles clock_nanosleep calls against _ALARM clockids
770 */
771static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
772 const struct timespec64 *tsreq)
773{
774 enum alarmtimer_type type = clock2alarm(clockid: which_clock);
775 struct restart_block *restart = &current->restart_block;
776 struct alarm alarm;
777 ktime_t exp;
778 int ret;
779
780 if (!alarmtimer_get_rtcdev())
781 return -EOPNOTSUPP;
782
783 if (flags & ~TIMER_ABSTIME)
784 return -EINVAL;
785
786 if (!capable(CAP_WAKE_ALARM))
787 return -EPERM;
788
789 alarm_init_on_stack(alarm: &alarm, type, function: alarmtimer_nsleep_wakeup);
790
791 exp = timespec64_to_ktime(ts: *tsreq);
792 /* Convert (if necessary) to absolute time */
793 if (flags != TIMER_ABSTIME) {
794 ktime_t now = alarm_bases[type].get_ktime();
795
796 exp = ktime_add_safe(lhs: now, rhs: exp);
797 } else {
798 exp = timens_ktime_to_host(clockid: which_clock, tim: exp);
799 }
800
801 ret = alarmtimer_do_nsleep(alarm: &alarm, absexp: exp, type);
802 if (ret != -ERESTART_RESTARTBLOCK)
803 return ret;
804
805 /* abs timers don't set remaining time or restart */
806 if (flags == TIMER_ABSTIME)
807 return -ERESTARTNOHAND;
808
809 restart->nanosleep.clockid = type;
810 restart->nanosleep.expires = exp;
811 set_restart_fn(restart, fn: alarm_timer_nsleep_restart);
812 return ret;
813}
814
815const struct k_clock alarm_clock = {
816 .clock_getres = alarm_clock_getres,
817 .clock_get_ktime = alarm_clock_get_ktime,
818 .clock_get_timespec = alarm_clock_get_timespec,
819 .timer_create = alarm_timer_create,
820 .timer_set = common_timer_set,
821 .timer_del = common_timer_del,
822 .timer_get = common_timer_get,
823 .timer_arm = alarm_timer_arm,
824 .timer_rearm = alarm_timer_rearm,
825 .timer_forward = alarm_timer_forward,
826 .timer_remaining = alarm_timer_remaining,
827 .timer_try_to_cancel = alarm_timer_try_to_cancel,
828 .timer_wait_running = alarm_timer_wait_running,
829 .nsleep = alarm_timer_nsleep,
830};
831#endif /* CONFIG_POSIX_TIMERS */
832
833
834/* Suspend hook structures */
835static const struct dev_pm_ops alarmtimer_pm_ops = {
836 .suspend = alarmtimer_suspend,
837 .resume = alarmtimer_resume,
838};
839
840static struct platform_driver alarmtimer_driver = {
841 .driver = {
842 .name = "alarmtimer",
843 .pm = &alarmtimer_pm_ops,
844 }
845};
846
847static void get_boottime_timespec(struct timespec64 *tp)
848{
849 ktime_get_boottime_ts64(ts: tp);
850 timens_add_boottime(ts: tp);
851}
852
853/**
854 * alarmtimer_init - Initialize alarm timer code
855 *
856 * This function initializes the alarm bases and registers
857 * the posix clock ids.
858 */
859static int __init alarmtimer_init(void)
860{
861 int error;
862 int i;
863
864 alarmtimer_rtc_timer_init();
865
866 /* Initialize alarm bases */
867 alarm_bases[ALARM_REALTIME].base_clockid = CLOCK_REALTIME;
868 alarm_bases[ALARM_REALTIME].get_ktime = &ktime_get_real;
869 alarm_bases[ALARM_REALTIME].get_timespec = ktime_get_real_ts64;
870 alarm_bases[ALARM_BOOTTIME].base_clockid = CLOCK_BOOTTIME;
871 alarm_bases[ALARM_BOOTTIME].get_ktime = &ktime_get_boottime;
872 alarm_bases[ALARM_BOOTTIME].get_timespec = get_boottime_timespec;
873 for (i = 0; i < ALARM_NUMTYPE; i++) {
874 timerqueue_init_head(head: &alarm_bases[i].timerqueue);
875 spin_lock_init(&alarm_bases[i].lock);
876 }
877
878 error = alarmtimer_rtc_interface_setup();
879 if (error)
880 return error;
881
882 error = platform_driver_register(&alarmtimer_driver);
883 if (error)
884 goto out_if;
885
886 return 0;
887out_if:
888 alarmtimer_rtc_interface_remove();
889 return error;
890}
891device_initcall(alarmtimer_init);
892

source code of linux/kernel/time/alarmtimer.c

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