1// SPDX-License-Identifier: GPL-2.0
2/*
3 * RTC subsystem, interface functions
4 *
5 * Copyright (C) 2005 Tower Technologies
6 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 *
8 * based on arch/arm/common/rtctime.c
9 */
10
11#include <linux/rtc.h>
12#include <linux/sched.h>
13#include <linux/module.h>
14#include <linux/log2.h>
15#include <linux/workqueue.h>
16
17#define CREATE_TRACE_POINTS
18#include <trace/events/rtc.h>
19
20static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
21static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
22
23static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
24{
25 time64_t secs;
26
27 if (!rtc->offset_secs)
28 return;
29
30 secs = rtc_tm_to_time64(tm);
31
32 /*
33 * Since the reading time values from RTC device are always in the RTC
34 * original valid range, but we need to skip the overlapped region
35 * between expanded range and original range, which is no need to add
36 * the offset.
37 */
38 if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
39 (rtc->start_secs < rtc->range_min &&
40 secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
41 return;
42
43 rtc_time64_to_tm(time: secs + rtc->offset_secs, tm);
44}
45
46static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
47{
48 time64_t secs;
49
50 if (!rtc->offset_secs)
51 return;
52
53 secs = rtc_tm_to_time64(tm);
54
55 /*
56 * If the setting time values are in the valid range of RTC hardware
57 * device, then no need to subtract the offset when setting time to RTC
58 * device. Otherwise we need to subtract the offset to make the time
59 * values are valid for RTC hardware device.
60 */
61 if (secs >= rtc->range_min && secs <= rtc->range_max)
62 return;
63
64 rtc_time64_to_tm(time: secs - rtc->offset_secs, tm);
65}
66
67static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
68{
69 if (rtc->range_min != rtc->range_max) {
70 time64_t time = rtc_tm_to_time64(tm);
71 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
72 rtc->range_min;
73 timeu64_t range_max = rtc->set_start_time ?
74 (rtc->start_secs + rtc->range_max - rtc->range_min) :
75 rtc->range_max;
76
77 if (time < range_min || time > range_max)
78 return -ERANGE;
79 }
80
81 return 0;
82}
83
84static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
85{
86 int err;
87
88 if (!rtc->ops) {
89 err = -ENODEV;
90 } else if (!rtc->ops->read_time) {
91 err = -EINVAL;
92 } else {
93 memset(tm, 0, sizeof(struct rtc_time));
94 err = rtc->ops->read_time(rtc->dev.parent, tm);
95 if (err < 0) {
96 dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
97 err);
98 return err;
99 }
100
101 rtc_add_offset(rtc, tm);
102
103 err = rtc_valid_tm(tm);
104 if (err < 0)
105 dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
106 }
107 return err;
108}
109
110int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
111{
112 int err;
113
114 err = mutex_lock_interruptible(&rtc->ops_lock);
115 if (err)
116 return err;
117
118 err = __rtc_read_time(rtc, tm);
119 mutex_unlock(lock: &rtc->ops_lock);
120
121 trace_rtc_read_time(secs: rtc_tm_to_time64(tm), err);
122 return err;
123}
124EXPORT_SYMBOL_GPL(rtc_read_time);
125
126int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
127{
128 int err, uie;
129
130 err = rtc_valid_tm(tm);
131 if (err != 0)
132 return err;
133
134 err = rtc_valid_range(rtc, tm);
135 if (err)
136 return err;
137
138 rtc_subtract_offset(rtc, tm);
139
140#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
141 uie = rtc->uie_rtctimer.enabled || rtc->uie_irq_active;
142#else
143 uie = rtc->uie_rtctimer.enabled;
144#endif
145 if (uie) {
146 err = rtc_update_irq_enable(rtc, enabled: 0);
147 if (err)
148 return err;
149 }
150
151 err = mutex_lock_interruptible(&rtc->ops_lock);
152 if (err)
153 return err;
154
155 if (!rtc->ops)
156 err = -ENODEV;
157 else if (rtc->ops->set_time)
158 err = rtc->ops->set_time(rtc->dev.parent, tm);
159 else
160 err = -EINVAL;
161
162 pm_stay_awake(dev: rtc->dev.parent);
163 mutex_unlock(lock: &rtc->ops_lock);
164 /* A timer might have just expired */
165 schedule_work(work: &rtc->irqwork);
166
167 if (uie) {
168 err = rtc_update_irq_enable(rtc, enabled: 1);
169 if (err)
170 return err;
171 }
172
173 trace_rtc_set_time(secs: rtc_tm_to_time64(tm), err);
174 return err;
175}
176EXPORT_SYMBOL_GPL(rtc_set_time);
177
178static int rtc_read_alarm_internal(struct rtc_device *rtc,
179 struct rtc_wkalrm *alarm)
180{
181 int err;
182
183 err = mutex_lock_interruptible(&rtc->ops_lock);
184 if (err)
185 return err;
186
187 if (!rtc->ops) {
188 err = -ENODEV;
189 } else if (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->read_alarm) {
190 err = -EINVAL;
191 } else {
192 alarm->enabled = 0;
193 alarm->pending = 0;
194 alarm->time.tm_sec = -1;
195 alarm->time.tm_min = -1;
196 alarm->time.tm_hour = -1;
197 alarm->time.tm_mday = -1;
198 alarm->time.tm_mon = -1;
199 alarm->time.tm_year = -1;
200 alarm->time.tm_wday = -1;
201 alarm->time.tm_yday = -1;
202 alarm->time.tm_isdst = -1;
203 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
204 }
205
206 mutex_unlock(lock: &rtc->ops_lock);
207
208 trace_rtc_read_alarm(secs: rtc_tm_to_time64(tm: &alarm->time), err);
209 return err;
210}
211
212int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
213{
214 int err;
215 struct rtc_time before, now;
216 int first_time = 1;
217 time64_t t_now, t_alm;
218 enum { none, day, month, year } missing = none;
219 unsigned int days;
220
221 /* The lower level RTC driver may return -1 in some fields,
222 * creating invalid alarm->time values, for reasons like:
223 *
224 * - The hardware may not be capable of filling them in;
225 * many alarms match only on time-of-day fields, not
226 * day/month/year calendar data.
227 *
228 * - Some hardware uses illegal values as "wildcard" match
229 * values, which non-Linux firmware (like a BIOS) may try
230 * to set up as e.g. "alarm 15 minutes after each hour".
231 * Linux uses only oneshot alarms.
232 *
233 * When we see that here, we deal with it by using values from
234 * a current RTC timestamp for any missing (-1) values. The
235 * RTC driver prevents "periodic alarm" modes.
236 *
237 * But this can be racey, because some fields of the RTC timestamp
238 * may have wrapped in the interval since we read the RTC alarm,
239 * which would lead to us inserting inconsistent values in place
240 * of the -1 fields.
241 *
242 * Reading the alarm and timestamp in the reverse sequence
243 * would have the same race condition, and not solve the issue.
244 *
245 * So, we must first read the RTC timestamp,
246 * then read the RTC alarm value,
247 * and then read a second RTC timestamp.
248 *
249 * If any fields of the second timestamp have changed
250 * when compared with the first timestamp, then we know
251 * our timestamp may be inconsistent with that used by
252 * the low-level rtc_read_alarm_internal() function.
253 *
254 * So, when the two timestamps disagree, we just loop and do
255 * the process again to get a fully consistent set of values.
256 *
257 * This could all instead be done in the lower level driver,
258 * but since more than one lower level RTC implementation needs it,
259 * then it's probably best to do it here instead of there..
260 */
261
262 /* Get the "before" timestamp */
263 err = rtc_read_time(rtc, &before);
264 if (err < 0)
265 return err;
266 do {
267 if (!first_time)
268 memcpy(&before, &now, sizeof(struct rtc_time));
269 first_time = 0;
270
271 /* get the RTC alarm values, which may be incomplete */
272 err = rtc_read_alarm_internal(rtc, alarm);
273 if (err)
274 return err;
275
276 /* full-function RTCs won't have such missing fields */
277 if (rtc_valid_tm(tm: &alarm->time) == 0) {
278 rtc_add_offset(rtc, tm: &alarm->time);
279 return 0;
280 }
281
282 /* get the "after" timestamp, to detect wrapped fields */
283 err = rtc_read_time(rtc, &now);
284 if (err < 0)
285 return err;
286
287 /* note that tm_sec is a "don't care" value here: */
288 } while (before.tm_min != now.tm_min ||
289 before.tm_hour != now.tm_hour ||
290 before.tm_mon != now.tm_mon ||
291 before.tm_year != now.tm_year);
292
293 /* Fill in the missing alarm fields using the timestamp; we
294 * know there's at least one since alarm->time is invalid.
295 */
296 if (alarm->time.tm_sec == -1)
297 alarm->time.tm_sec = now.tm_sec;
298 if (alarm->time.tm_min == -1)
299 alarm->time.tm_min = now.tm_min;
300 if (alarm->time.tm_hour == -1)
301 alarm->time.tm_hour = now.tm_hour;
302
303 /* For simplicity, only support date rollover for now */
304 if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
305 alarm->time.tm_mday = now.tm_mday;
306 missing = day;
307 }
308 if ((unsigned int)alarm->time.tm_mon >= 12) {
309 alarm->time.tm_mon = now.tm_mon;
310 if (missing == none)
311 missing = month;
312 }
313 if (alarm->time.tm_year == -1) {
314 alarm->time.tm_year = now.tm_year;
315 if (missing == none)
316 missing = year;
317 }
318
319 /* Can't proceed if alarm is still invalid after replacing
320 * missing fields.
321 */
322 err = rtc_valid_tm(tm: &alarm->time);
323 if (err)
324 goto done;
325
326 /* with luck, no rollover is needed */
327 t_now = rtc_tm_to_time64(tm: &now);
328 t_alm = rtc_tm_to_time64(tm: &alarm->time);
329 if (t_now < t_alm)
330 goto done;
331
332 switch (missing) {
333 /* 24 hour rollover ... if it's now 10am Monday, an alarm that
334 * that will trigger at 5am will do so at 5am Tuesday, which
335 * could also be in the next month or year. This is a common
336 * case, especially for PCs.
337 */
338 case day:
339 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
340 t_alm += 24 * 60 * 60;
341 rtc_time64_to_tm(time: t_alm, tm: &alarm->time);
342 break;
343
344 /* Month rollover ... if it's the 31th, an alarm on the 3rd will
345 * be next month. An alarm matching on the 30th, 29th, or 28th
346 * may end up in the month after that! Many newer PCs support
347 * this type of alarm.
348 */
349 case month:
350 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
351 do {
352 if (alarm->time.tm_mon < 11) {
353 alarm->time.tm_mon++;
354 } else {
355 alarm->time.tm_mon = 0;
356 alarm->time.tm_year++;
357 }
358 days = rtc_month_days(month: alarm->time.tm_mon,
359 year: alarm->time.tm_year);
360 } while (days < alarm->time.tm_mday);
361 break;
362
363 /* Year rollover ... easy except for leap years! */
364 case year:
365 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
366 do {
367 alarm->time.tm_year++;
368 } while (!is_leap_year(year: alarm->time.tm_year + 1900) &&
369 rtc_valid_tm(tm: &alarm->time) != 0);
370 break;
371
372 default:
373 dev_warn(&rtc->dev, "alarm rollover not handled\n");
374 }
375
376 err = rtc_valid_tm(tm: &alarm->time);
377
378done:
379 if (err && alarm->enabled)
380 dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
381 &alarm->time);
382
383 return err;
384}
385
386int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
387{
388 int err;
389
390 err = mutex_lock_interruptible(&rtc->ops_lock);
391 if (err)
392 return err;
393 if (!rtc->ops) {
394 err = -ENODEV;
395 } else if (!test_bit(RTC_FEATURE_ALARM, rtc->features)) {
396 err = -EINVAL;
397 } else {
398 memset(alarm, 0, sizeof(struct rtc_wkalrm));
399 alarm->enabled = rtc->aie_timer.enabled;
400 alarm->time = rtc_ktime_to_tm(kt: rtc->aie_timer.node.expires);
401 }
402 mutex_unlock(lock: &rtc->ops_lock);
403
404 trace_rtc_read_alarm(secs: rtc_tm_to_time64(tm: &alarm->time), err);
405 return err;
406}
407EXPORT_SYMBOL_GPL(rtc_read_alarm);
408
409static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
410{
411 struct rtc_time tm;
412 time64_t now, scheduled;
413 int err;
414
415 err = rtc_valid_tm(tm: &alarm->time);
416 if (err)
417 return err;
418
419 scheduled = rtc_tm_to_time64(tm: &alarm->time);
420
421 /* Make sure we're not setting alarms in the past */
422 err = __rtc_read_time(rtc, tm: &tm);
423 if (err)
424 return err;
425 now = rtc_tm_to_time64(tm: &tm);
426
427 if (scheduled <= now)
428 return -ETIME;
429 /*
430 * XXX - We just checked to make sure the alarm time is not
431 * in the past, but there is still a race window where if
432 * the is alarm set for the next second and the second ticks
433 * over right here, before we set the alarm.
434 */
435
436 rtc_subtract_offset(rtc, tm: &alarm->time);
437
438 if (!rtc->ops)
439 err = -ENODEV;
440 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
441 err = -EINVAL;
442 else
443 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
444
445 trace_rtc_set_alarm(secs: rtc_tm_to_time64(tm: &alarm->time), err);
446 return err;
447}
448
449int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
450{
451 ktime_t alarm_time;
452 int err;
453
454 if (!rtc->ops)
455 return -ENODEV;
456 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
457 return -EINVAL;
458
459 err = rtc_valid_tm(tm: &alarm->time);
460 if (err != 0)
461 return err;
462
463 err = rtc_valid_range(rtc, tm: &alarm->time);
464 if (err)
465 return err;
466
467 err = mutex_lock_interruptible(&rtc->ops_lock);
468 if (err)
469 return err;
470 if (rtc->aie_timer.enabled)
471 rtc_timer_remove(rtc, timer: &rtc->aie_timer);
472
473 alarm_time = rtc_tm_to_ktime(tm: alarm->time);
474 /*
475 * Round down so we never miss a deadline, checking for past deadline is
476 * done in __rtc_set_alarm
477 */
478 if (test_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features))
479 alarm_time = ktime_sub_ns(alarm_time, (u64)alarm->time.tm_sec * NSEC_PER_SEC);
480
481 rtc->aie_timer.node.expires = alarm_time;
482 rtc->aie_timer.period = 0;
483 if (alarm->enabled)
484 err = rtc_timer_enqueue(rtc, timer: &rtc->aie_timer);
485
486 mutex_unlock(lock: &rtc->ops_lock);
487
488 return err;
489}
490EXPORT_SYMBOL_GPL(rtc_set_alarm);
491
492/* Called once per device from rtc_device_register */
493int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
494{
495 int err;
496 struct rtc_time now;
497
498 err = rtc_valid_tm(tm: &alarm->time);
499 if (err != 0)
500 return err;
501
502 err = rtc_read_time(rtc, &now);
503 if (err)
504 return err;
505
506 err = mutex_lock_interruptible(&rtc->ops_lock);
507 if (err)
508 return err;
509
510 rtc->aie_timer.node.expires = rtc_tm_to_ktime(tm: alarm->time);
511 rtc->aie_timer.period = 0;
512
513 /* Alarm has to be enabled & in the future for us to enqueue it */
514 if (alarm->enabled && (rtc_tm_to_ktime(tm: now) <
515 rtc->aie_timer.node.expires)) {
516 rtc->aie_timer.enabled = 1;
517 timerqueue_add(head: &rtc->timerqueue, node: &rtc->aie_timer.node);
518 trace_rtc_timer_enqueue(timer: &rtc->aie_timer);
519 }
520 mutex_unlock(lock: &rtc->ops_lock);
521 return err;
522}
523EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
524
525int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
526{
527 int err;
528
529 err = mutex_lock_interruptible(&rtc->ops_lock);
530 if (err)
531 return err;
532
533 if (rtc->aie_timer.enabled != enabled) {
534 if (enabled)
535 err = rtc_timer_enqueue(rtc, timer: &rtc->aie_timer);
536 else
537 rtc_timer_remove(rtc, timer: &rtc->aie_timer);
538 }
539
540 if (err)
541 /* nothing */;
542 else if (!rtc->ops)
543 err = -ENODEV;
544 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
545 err = -EINVAL;
546 else
547 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
548
549 mutex_unlock(lock: &rtc->ops_lock);
550
551 trace_rtc_alarm_irq_enable(enabled, err);
552 return err;
553}
554EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
555
556int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
557{
558 int err;
559
560 err = mutex_lock_interruptible(&rtc->ops_lock);
561 if (err)
562 return err;
563
564#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
565 if (enabled == 0 && rtc->uie_irq_active) {
566 mutex_unlock(lock: &rtc->ops_lock);
567 return rtc_dev_update_irq_enable_emul(rtc, enabled: 0);
568 }
569#endif
570 /* make sure we're changing state */
571 if (rtc->uie_rtctimer.enabled == enabled)
572 goto out;
573
574 if (!test_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features) ||
575 !test_bit(RTC_FEATURE_ALARM, rtc->features)) {
576 mutex_unlock(lock: &rtc->ops_lock);
577#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
578 return rtc_dev_update_irq_enable_emul(rtc, enabled);
579#else
580 return -EINVAL;
581#endif
582 }
583
584 if (enabled) {
585 struct rtc_time tm;
586 ktime_t now, onesec;
587
588 err = __rtc_read_time(rtc, tm: &tm);
589 if (err)
590 goto out;
591 onesec = ktime_set(secs: 1, nsecs: 0);
592 now = rtc_tm_to_ktime(tm);
593 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
594 rtc->uie_rtctimer.period = ktime_set(secs: 1, nsecs: 0);
595 err = rtc_timer_enqueue(rtc, timer: &rtc->uie_rtctimer);
596 } else {
597 rtc_timer_remove(rtc, timer: &rtc->uie_rtctimer);
598 }
599
600out:
601 mutex_unlock(lock: &rtc->ops_lock);
602
603 return err;
604}
605EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
606
607/**
608 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
609 * @rtc: pointer to the rtc device
610 * @num: number of occurence of the event
611 * @mode: type of the event, RTC_AF, RTC_UF of RTC_PF
612 *
613 * This function is called when an AIE, UIE or PIE mode interrupt
614 * has occurred (or been emulated).
615 *
616 */
617void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
618{
619 unsigned long flags;
620
621 /* mark one irq of the appropriate mode */
622 spin_lock_irqsave(&rtc->irq_lock, flags);
623 rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF | mode);
624 spin_unlock_irqrestore(lock: &rtc->irq_lock, flags);
625
626 wake_up_interruptible(&rtc->irq_queue);
627 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
628}
629
630/**
631 * rtc_aie_update_irq - AIE mode rtctimer hook
632 * @rtc: pointer to the rtc_device
633 *
634 * This functions is called when the aie_timer expires.
635 */
636void rtc_aie_update_irq(struct rtc_device *rtc)
637{
638 rtc_handle_legacy_irq(rtc, num: 1, RTC_AF);
639}
640
641/**
642 * rtc_uie_update_irq - UIE mode rtctimer hook
643 * @rtc: pointer to the rtc_device
644 *
645 * This functions is called when the uie_timer expires.
646 */
647void rtc_uie_update_irq(struct rtc_device *rtc)
648{
649 rtc_handle_legacy_irq(rtc, num: 1, RTC_UF);
650}
651
652/**
653 * rtc_pie_update_irq - PIE mode hrtimer hook
654 * @timer: pointer to the pie mode hrtimer
655 *
656 * This function is used to emulate PIE mode interrupts
657 * using an hrtimer. This function is called when the periodic
658 * hrtimer expires.
659 */
660enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
661{
662 struct rtc_device *rtc;
663 ktime_t period;
664 u64 count;
665
666 rtc = container_of(timer, struct rtc_device, pie_timer);
667
668 period = NSEC_PER_SEC / rtc->irq_freq;
669 count = hrtimer_forward_now(timer, interval: period);
670
671 rtc_handle_legacy_irq(rtc, num: count, RTC_PF);
672
673 return HRTIMER_RESTART;
674}
675
676/**
677 * rtc_update_irq - Triggered when a RTC interrupt occurs.
678 * @rtc: the rtc device
679 * @num: how many irqs are being reported (usually one)
680 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
681 * Context: any
682 */
683void rtc_update_irq(struct rtc_device *rtc,
684 unsigned long num, unsigned long events)
685{
686 if (IS_ERR_OR_NULL(ptr: rtc))
687 return;
688
689 pm_stay_awake(dev: rtc->dev.parent);
690 schedule_work(work: &rtc->irqwork);
691}
692EXPORT_SYMBOL_GPL(rtc_update_irq);
693
694struct rtc_device *rtc_class_open(const char *name)
695{
696 struct device *dev;
697 struct rtc_device *rtc = NULL;
698
699 dev = class_find_device_by_name(class: rtc_class, name);
700 if (dev)
701 rtc = to_rtc_device(dev);
702
703 if (rtc) {
704 if (!try_module_get(module: rtc->owner)) {
705 put_device(dev);
706 rtc = NULL;
707 }
708 }
709
710 return rtc;
711}
712EXPORT_SYMBOL_GPL(rtc_class_open);
713
714void rtc_class_close(struct rtc_device *rtc)
715{
716 module_put(module: rtc->owner);
717 put_device(dev: &rtc->dev);
718}
719EXPORT_SYMBOL_GPL(rtc_class_close);
720
721static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
722{
723 /*
724 * We always cancel the timer here first, because otherwise
725 * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
726 * when we manage to start the timer before the callback
727 * returns HRTIMER_RESTART.
728 *
729 * We cannot use hrtimer_cancel() here as a running callback
730 * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
731 * would spin forever.
732 */
733 if (hrtimer_try_to_cancel(timer: &rtc->pie_timer) < 0)
734 return -1;
735
736 if (enabled) {
737 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
738
739 hrtimer_start(timer: &rtc->pie_timer, tim: period, mode: HRTIMER_MODE_REL);
740 }
741 return 0;
742}
743
744/**
745 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
746 * @rtc: the rtc device
747 * @enabled: true to enable periodic IRQs
748 * Context: any
749 *
750 * Note that rtc_irq_set_freq() should previously have been used to
751 * specify the desired frequency of periodic IRQ.
752 */
753int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
754{
755 int err = 0;
756
757 while (rtc_update_hrtimer(rtc, enabled) < 0)
758 cpu_relax();
759
760 rtc->pie_enabled = enabled;
761
762 trace_rtc_irq_set_state(enabled, err);
763 return err;
764}
765
766/**
767 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
768 * @rtc: the rtc device
769 * @freq: positive frequency
770 * Context: any
771 *
772 * Note that rtc_irq_set_state() is used to enable or disable the
773 * periodic IRQs.
774 */
775int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
776{
777 int err = 0;
778
779 if (freq <= 0 || freq > RTC_MAX_FREQ)
780 return -EINVAL;
781
782 rtc->irq_freq = freq;
783 while (rtc->pie_enabled && rtc_update_hrtimer(rtc, enabled: 1) < 0)
784 cpu_relax();
785
786 trace_rtc_irq_set_freq(freq, err);
787 return err;
788}
789
790/**
791 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
792 * @rtc: rtc device
793 * @timer: timer being added.
794 *
795 * Enqueues a timer onto the rtc devices timerqueue and sets
796 * the next alarm event appropriately.
797 *
798 * Sets the enabled bit on the added timer.
799 *
800 * Must hold ops_lock for proper serialization of timerqueue
801 */
802static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
803{
804 struct timerqueue_node *next = timerqueue_getnext(head: &rtc->timerqueue);
805 struct rtc_time tm;
806 ktime_t now;
807 int err;
808
809 err = __rtc_read_time(rtc, tm: &tm);
810 if (err)
811 return err;
812
813 timer->enabled = 1;
814 now = rtc_tm_to_ktime(tm);
815
816 /* Skip over expired timers */
817 while (next) {
818 if (next->expires >= now)
819 break;
820 next = timerqueue_iterate_next(node: next);
821 }
822
823 timerqueue_add(head: &rtc->timerqueue, node: &timer->node);
824 trace_rtc_timer_enqueue(timer);
825 if (!next || ktime_before(cmp1: timer->node.expires, cmp2: next->expires)) {
826 struct rtc_wkalrm alarm;
827
828 alarm.time = rtc_ktime_to_tm(kt: timer->node.expires);
829 alarm.enabled = 1;
830 err = __rtc_set_alarm(rtc, alarm: &alarm);
831 if (err == -ETIME) {
832 pm_stay_awake(dev: rtc->dev.parent);
833 schedule_work(work: &rtc->irqwork);
834 } else if (err) {
835 timerqueue_del(head: &rtc->timerqueue, node: &timer->node);
836 trace_rtc_timer_dequeue(timer);
837 timer->enabled = 0;
838 return err;
839 }
840 }
841 return 0;
842}
843
844static void rtc_alarm_disable(struct rtc_device *rtc)
845{
846 if (!rtc->ops || !test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
847 return;
848
849 rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
850 trace_rtc_alarm_irq_enable(enabled: 0, err: 0);
851}
852
853/**
854 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
855 * @rtc: rtc device
856 * @timer: timer being removed.
857 *
858 * Removes a timer onto the rtc devices timerqueue and sets
859 * the next alarm event appropriately.
860 *
861 * Clears the enabled bit on the removed timer.
862 *
863 * Must hold ops_lock for proper serialization of timerqueue
864 */
865static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
866{
867 struct timerqueue_node *next = timerqueue_getnext(head: &rtc->timerqueue);
868
869 timerqueue_del(head: &rtc->timerqueue, node: &timer->node);
870 trace_rtc_timer_dequeue(timer);
871 timer->enabled = 0;
872 if (next == &timer->node) {
873 struct rtc_wkalrm alarm;
874 int err;
875
876 next = timerqueue_getnext(head: &rtc->timerqueue);
877 if (!next) {
878 rtc_alarm_disable(rtc);
879 return;
880 }
881 alarm.time = rtc_ktime_to_tm(kt: next->expires);
882 alarm.enabled = 1;
883 err = __rtc_set_alarm(rtc, alarm: &alarm);
884 if (err == -ETIME) {
885 pm_stay_awake(dev: rtc->dev.parent);
886 schedule_work(work: &rtc->irqwork);
887 }
888 }
889}
890
891/**
892 * rtc_timer_do_work - Expires rtc timers
893 * @work: work item
894 *
895 * Expires rtc timers. Reprograms next alarm event if needed.
896 * Called via worktask.
897 *
898 * Serializes access to timerqueue via ops_lock mutex
899 */
900void rtc_timer_do_work(struct work_struct *work)
901{
902 struct rtc_timer *timer;
903 struct timerqueue_node *next;
904 ktime_t now;
905 struct rtc_time tm;
906
907 struct rtc_device *rtc =
908 container_of(work, struct rtc_device, irqwork);
909
910 mutex_lock(&rtc->ops_lock);
911again:
912 __rtc_read_time(rtc, tm: &tm);
913 now = rtc_tm_to_ktime(tm);
914 while ((next = timerqueue_getnext(head: &rtc->timerqueue))) {
915 if (next->expires > now)
916 break;
917
918 /* expire timer */
919 timer = container_of(next, struct rtc_timer, node);
920 timerqueue_del(head: &rtc->timerqueue, node: &timer->node);
921 trace_rtc_timer_dequeue(timer);
922 timer->enabled = 0;
923 if (timer->func)
924 timer->func(timer->rtc);
925
926 trace_rtc_timer_fired(timer);
927 /* Re-add/fwd periodic timers */
928 if (ktime_to_ns(kt: timer->period)) {
929 timer->node.expires = ktime_add(timer->node.expires,
930 timer->period);
931 timer->enabled = 1;
932 timerqueue_add(head: &rtc->timerqueue, node: &timer->node);
933 trace_rtc_timer_enqueue(timer);
934 }
935 }
936
937 /* Set next alarm */
938 if (next) {
939 struct rtc_wkalrm alarm;
940 int err;
941 int retry = 3;
942
943 alarm.time = rtc_ktime_to_tm(kt: next->expires);
944 alarm.enabled = 1;
945reprogram:
946 err = __rtc_set_alarm(rtc, alarm: &alarm);
947 if (err == -ETIME) {
948 goto again;
949 } else if (err) {
950 if (retry-- > 0)
951 goto reprogram;
952
953 timer = container_of(next, struct rtc_timer, node);
954 timerqueue_del(head: &rtc->timerqueue, node: &timer->node);
955 trace_rtc_timer_dequeue(timer);
956 timer->enabled = 0;
957 dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
958 goto again;
959 }
960 } else {
961 rtc_alarm_disable(rtc);
962 }
963
964 pm_relax(dev: rtc->dev.parent);
965 mutex_unlock(lock: &rtc->ops_lock);
966}
967
968/* rtc_timer_init - Initializes an rtc_timer
969 * @timer: timer to be intiialized
970 * @f: function pointer to be called when timer fires
971 * @rtc: pointer to the rtc_device
972 *
973 * Kernel interface to initializing an rtc_timer.
974 */
975void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
976 struct rtc_device *rtc)
977{
978 timerqueue_init(node: &timer->node);
979 timer->enabled = 0;
980 timer->func = f;
981 timer->rtc = rtc;
982}
983
984/* rtc_timer_start - Sets an rtc_timer to fire in the future
985 * @ rtc: rtc device to be used
986 * @ timer: timer being set
987 * @ expires: time at which to expire the timer
988 * @ period: period that the timer will recur
989 *
990 * Kernel interface to set an rtc_timer
991 */
992int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
993 ktime_t expires, ktime_t period)
994{
995 int ret = 0;
996
997 mutex_lock(&rtc->ops_lock);
998 if (timer->enabled)
999 rtc_timer_remove(rtc, timer);
1000
1001 timer->node.expires = expires;
1002 timer->period = period;
1003
1004 ret = rtc_timer_enqueue(rtc, timer);
1005
1006 mutex_unlock(lock: &rtc->ops_lock);
1007 return ret;
1008}
1009
1010/* rtc_timer_cancel - Stops an rtc_timer
1011 * @ rtc: rtc device to be used
1012 * @ timer: timer being set
1013 *
1014 * Kernel interface to cancel an rtc_timer
1015 */
1016void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1017{
1018 mutex_lock(&rtc->ops_lock);
1019 if (timer->enabled)
1020 rtc_timer_remove(rtc, timer);
1021 mutex_unlock(lock: &rtc->ops_lock);
1022}
1023
1024/**
1025 * rtc_read_offset - Read the amount of rtc offset in parts per billion
1026 * @rtc: rtc device to be used
1027 * @offset: the offset in parts per billion
1028 *
1029 * see below for details.
1030 *
1031 * Kernel interface to read rtc clock offset
1032 * Returns 0 on success, or a negative number on error.
1033 * If read_offset() is not implemented for the rtc, return -EINVAL
1034 */
1035int rtc_read_offset(struct rtc_device *rtc, long *offset)
1036{
1037 int ret;
1038
1039 if (!rtc->ops)
1040 return -ENODEV;
1041
1042 if (!rtc->ops->read_offset)
1043 return -EINVAL;
1044
1045 mutex_lock(&rtc->ops_lock);
1046 ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1047 mutex_unlock(lock: &rtc->ops_lock);
1048
1049 trace_rtc_read_offset(offset: *offset, err: ret);
1050 return ret;
1051}
1052
1053/**
1054 * rtc_set_offset - Adjusts the duration of the average second
1055 * @rtc: rtc device to be used
1056 * @offset: the offset in parts per billion
1057 *
1058 * Some rtc's allow an adjustment to the average duration of a second
1059 * to compensate for differences in the actual clock rate due to temperature,
1060 * the crystal, capacitor, etc.
1061 *
1062 * The adjustment applied is as follows:
1063 * t = t0 * (1 + offset * 1e-9)
1064 * where t0 is the measured length of 1 RTC second with offset = 0
1065 *
1066 * Kernel interface to adjust an rtc clock offset.
1067 * Return 0 on success, or a negative number on error.
1068 * If the rtc offset is not setable (or not implemented), return -EINVAL
1069 */
1070int rtc_set_offset(struct rtc_device *rtc, long offset)
1071{
1072 int ret;
1073
1074 if (!rtc->ops)
1075 return -ENODEV;
1076
1077 if (!rtc->ops->set_offset)
1078 return -EINVAL;
1079
1080 mutex_lock(&rtc->ops_lock);
1081 ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1082 mutex_unlock(lock: &rtc->ops_lock);
1083
1084 trace_rtc_set_offset(offset, err: ret);
1085 return ret;
1086}
1087

source code of linux/drivers/rtc/interface.c