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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(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(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(&rtc->ops_lock);
120
121 trace_rtc_read_time(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, 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(rtc->dev.parent);
163 mutex_unlock(&rtc->ops_lock);
164 /* A timer might have just expired */
165 schedule_work(&rtc->irqwork);
166
167 if (uie) {
168 err = rtc_update_irq_enable(rtc, 1);
169 if (err)
170 return err;
171 }
172
173 trace_rtc_set_time(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(&rtc->ops_lock);
207
208 trace_rtc_read_alarm(rtc_tm_to_time64(&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 err = rtc_valid_tm(&alarm->time);
278 if (!err)
279 goto done;
280
281 /* get the "after" timestamp, to detect wrapped fields */
282 err = rtc_read_time(rtc, &now);
283 if (err < 0)
284 return err;
285
286 /* note that tm_sec is a "don't care" value here: */
287 } while (before.tm_min != now.tm_min ||
288 before.tm_hour != now.tm_hour ||
289 before.tm_mon != now.tm_mon ||
290 before.tm_year != now.tm_year);
291
292 /* Fill in the missing alarm fields using the timestamp; we
293 * know there's at least one since alarm->time is invalid.
294 */
295 if (alarm->time.tm_sec == -1)
296 alarm->time.tm_sec = now.tm_sec;
297 if (alarm->time.tm_min == -1)
298 alarm->time.tm_min = now.tm_min;
299 if (alarm->time.tm_hour == -1)
300 alarm->time.tm_hour = now.tm_hour;
301
302 /* For simplicity, only support date rollover for now */
303 if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
304 alarm->time.tm_mday = now.tm_mday;
305 missing = day;
306 }
307 if ((unsigned int)alarm->time.tm_mon >= 12) {
308 alarm->time.tm_mon = now.tm_mon;
309 if (missing == none)
310 missing = month;
311 }
312 if (alarm->time.tm_year == -1) {
313 alarm->time.tm_year = now.tm_year;
314 if (missing == none)
315 missing = year;
316 }
317
318 /* Can't proceed if alarm is still invalid after replacing
319 * missing fields.
320 */
321 err = rtc_valid_tm(&alarm->time);
322 if (err)
323 goto done;
324
325 /* with luck, no rollover is needed */
326 t_now = rtc_tm_to_time64(&now);
327 t_alm = rtc_tm_to_time64(&alarm->time);
328 if (t_now < t_alm)
329 goto done;
330
331 switch (missing) {
332 /* 24 hour rollover ... if it's now 10am Monday, an alarm that
333 * that will trigger at 5am will do so at 5am Tuesday, which
334 * could also be in the next month or year. This is a common
335 * case, especially for PCs.
336 */
337 case day:
338 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
339 t_alm += 24 * 60 * 60;
340 rtc_time64_to_tm(t_alm, &alarm->time);
341 break;
342
343 /* Month rollover ... if it's the 31th, an alarm on the 3rd will
344 * be next month. An alarm matching on the 30th, 29th, or 28th
345 * may end up in the month after that! Many newer PCs support
346 * this type of alarm.
347 */
348 case month:
349 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
350 do {
351 if (alarm->time.tm_mon < 11) {
352 alarm->time.tm_mon++;
353 } else {
354 alarm->time.tm_mon = 0;
355 alarm->time.tm_year++;
356 }
357 days = rtc_month_days(alarm->time.tm_mon,
358 alarm->time.tm_year);
359 } while (days < alarm->time.tm_mday);
360 break;
361
362 /* Year rollover ... easy except for leap years! */
363 case year:
364 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
365 do {
366 alarm->time.tm_year++;
367 } while (!is_leap_year(alarm->time.tm_year + 1900) &&
368 rtc_valid_tm(&alarm->time) != 0);
369 break;
370
371 default:
372 dev_warn(&rtc->dev, "alarm rollover not handled\n");
373 }
374
375 err = rtc_valid_tm(&alarm->time);
376
377done:
378 if (err && alarm->enabled)
379 dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
380 &alarm->time);
381 else
382 rtc_add_offset(rtc, &alarm->time);
383
384 return err;
385}
386
387int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
388{
389 int err;
390
391 err = mutex_lock_interruptible(&rtc->ops_lock);
392 if (err)
393 return err;
394 if (!rtc->ops) {
395 err = -ENODEV;
396 } else if (!test_bit(RTC_FEATURE_ALARM, rtc->features)) {
397 err = -EINVAL;
398 } else {
399 memset(alarm, 0, sizeof(struct rtc_wkalrm));
400 alarm->enabled = rtc->aie_timer.enabled;
401 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
402 }
403 mutex_unlock(&rtc->ops_lock);
404
405 trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
406 return err;
407}
408EXPORT_SYMBOL_GPL(rtc_read_alarm);
409
410static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
411{
412 struct rtc_time tm;
413 time64_t now, scheduled;
414 int err;
415
416 err = rtc_valid_tm(&alarm->time);
417 if (err)
418 return err;
419
420 scheduled = rtc_tm_to_time64(&alarm->time);
421
422 /* Make sure we're not setting alarms in the past */
423 err = __rtc_read_time(rtc, &tm);
424 if (err)
425 return err;
426 now = rtc_tm_to_time64(&tm);
427
428 if (scheduled <= now)
429 return -ETIME;
430 /*
431 * XXX - We just checked to make sure the alarm time is not
432 * in the past, but there is still a race window where if
433 * the is alarm set for the next second and the second ticks
434 * over right here, before we set the alarm.
435 */
436
437 rtc_subtract_offset(rtc, &alarm->time);
438
439 if (!rtc->ops)
440 err = -ENODEV;
441 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
442 err = -EINVAL;
443 else
444 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
445
446 trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
447 return err;
448}
449
450int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
451{
452 ktime_t alarm_time;
453 int err;
454
455 if (!rtc->ops)
456 return -ENODEV;
457 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
458 return -EINVAL;
459
460 err = rtc_valid_tm(&alarm->time);
461 if (err != 0)
462 return err;
463
464 err = rtc_valid_range(rtc, &alarm->time);
465 if (err)
466 return err;
467
468 err = mutex_lock_interruptible(&rtc->ops_lock);
469 if (err)
470 return err;
471 if (rtc->aie_timer.enabled)
472 rtc_timer_remove(rtc, &rtc->aie_timer);
473
474 alarm_time = rtc_tm_to_ktime(alarm->time);
475 /*
476 * Round down so we never miss a deadline, checking for past deadline is
477 * done in __rtc_set_alarm
478 */
479 if (test_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features))
480 alarm_time = ktime_sub_ns(alarm_time, (u64)alarm->time.tm_sec * NSEC_PER_SEC);
481
482 rtc->aie_timer.node.expires = alarm_time;
483 rtc->aie_timer.period = 0;
484 if (alarm->enabled)
485 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
486
487 mutex_unlock(&rtc->ops_lock);
488
489 return err;
490}
491EXPORT_SYMBOL_GPL(rtc_set_alarm);
492
493/* Called once per device from rtc_device_register */
494int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
495{
496 int err;
497 struct rtc_time now;
498
499 err = rtc_valid_tm(&alarm->time);
500 if (err != 0)
501 return err;
502
503 err = rtc_read_time(rtc, &now);
504 if (err)
505 return err;
506
507 err = mutex_lock_interruptible(&rtc->ops_lock);
508 if (err)
509 return err;
510
511 rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
512 rtc->aie_timer.period = 0;
513
514 /* Alarm has to be enabled & in the future for us to enqueue it */
515 if (alarm->enabled && (rtc_tm_to_ktime(now) <
516 rtc->aie_timer.node.expires)) {
517 rtc->aie_timer.enabled = 1;
518 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
519 trace_rtc_timer_enqueue(&rtc->aie_timer);
520 }
521 mutex_unlock(&rtc->ops_lock);
522 return err;
523}
524EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
525
526int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
527{
528 int err;
529
530 err = mutex_lock_interruptible(&rtc->ops_lock);
531 if (err)
532 return err;
533
534 if (rtc->aie_timer.enabled != enabled) {
535 if (enabled)
536 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
537 else
538 rtc_timer_remove(rtc, &rtc->aie_timer);
539 }
540
541 if (err)
542 /* nothing */;
543 else if (!rtc->ops)
544 err = -ENODEV;
545 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
546 err = -EINVAL;
547 else
548 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
549
550 mutex_unlock(&rtc->ops_lock);
551
552 trace_rtc_alarm_irq_enable(enabled, err);
553 return err;
554}
555EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
556
557int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
558{
559 int err;
560
561 err = mutex_lock_interruptible(&rtc->ops_lock);
562 if (err)
563 return err;
564
565#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
566 if (enabled == 0 && rtc->uie_irq_active) {
567 mutex_unlock(&rtc->ops_lock);
568 return rtc_dev_update_irq_enable_emul(rtc, 0);
569 }
570#endif
571 /* make sure we're changing state */
572 if (rtc->uie_rtctimer.enabled == enabled)
573 goto out;
574
575 if (!test_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features) ||
576 !test_bit(RTC_FEATURE_ALARM, rtc->features)) {
577 mutex_unlock(&rtc->ops_lock);
578#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
579 return rtc_dev_update_irq_enable_emul(rtc, enabled);
580#else
581 return -EINVAL;
582#endif
583 }
584
585 if (enabled) {
586 struct rtc_time tm;
587 ktime_t now, onesec;
588
589 err = __rtc_read_time(rtc, &tm);
590 if (err)
591 goto out;
592 onesec = ktime_set(1, 0);
593 now = rtc_tm_to_ktime(tm);
594 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
595 rtc->uie_rtctimer.period = ktime_set(1, 0);
596 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
597 } else {
598 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
599 }
600
601out:
602 mutex_unlock(&rtc->ops_lock);
603
604 return err;
605}
606EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
607
608/**
609 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
610 * @rtc: pointer to the rtc device
611 * @num: number of occurence of the event
612 * @mode: type of the event, RTC_AF, RTC_UF of RTC_PF
613 *
614 * This function is called when an AIE, UIE or PIE mode interrupt
615 * has occurred (or been emulated).
616 *
617 */
618void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
619{
620 unsigned long flags;
621
622 /* mark one irq of the appropriate mode */
623 spin_lock_irqsave(&rtc->irq_lock, flags);
624 rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF | mode);
625 spin_unlock_irqrestore(&rtc->irq_lock, flags);
626
627 wake_up_interruptible(&rtc->irq_queue);
628 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
629}
630
631/**
632 * rtc_aie_update_irq - AIE mode rtctimer hook
633 * @rtc: pointer to the rtc_device
634 *
635 * This functions is called when the aie_timer expires.
636 */
637void rtc_aie_update_irq(struct rtc_device *rtc)
638{
639 rtc_handle_legacy_irq(rtc, 1, RTC_AF);
640}
641
642/**
643 * rtc_uie_update_irq - UIE mode rtctimer hook
644 * @rtc: pointer to the rtc_device
645 *
646 * This functions is called when the uie_timer expires.
647 */
648void rtc_uie_update_irq(struct rtc_device *rtc)
649{
650 rtc_handle_legacy_irq(rtc, 1, RTC_UF);
651}
652
653/**
654 * rtc_pie_update_irq - PIE mode hrtimer hook
655 * @timer: pointer to the pie mode hrtimer
656 *
657 * This function is used to emulate PIE mode interrupts
658 * using an hrtimer. This function is called when the periodic
659 * hrtimer expires.
660 */
661enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
662{
663 struct rtc_device *rtc;
664 ktime_t period;
665 u64 count;
666
667 rtc = container_of(timer, struct rtc_device, pie_timer);
668
669 period = NSEC_PER_SEC / rtc->irq_freq;
670 count = hrtimer_forward_now(timer, period);
671
672 rtc_handle_legacy_irq(rtc, count, RTC_PF);
673
674 return HRTIMER_RESTART;
675}
676
677/**
678 * rtc_update_irq - Triggered when a RTC interrupt occurs.
679 * @rtc: the rtc device
680 * @num: how many irqs are being reported (usually one)
681 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
682 * Context: any
683 */
684void rtc_update_irq(struct rtc_device *rtc,
685 unsigned long num, unsigned long events)
686{
687 if (IS_ERR_OR_NULL(rtc))
688 return;
689
690 pm_stay_awake(rtc->dev.parent);
691 schedule_work(&rtc->irqwork);
692}
693EXPORT_SYMBOL_GPL(rtc_update_irq);
694
695struct rtc_device *rtc_class_open(const char *name)
696{
697 struct device *dev;
698 struct rtc_device *rtc = NULL;
699
700 dev = class_find_device_by_name(&rtc_class, name);
701 if (dev)
702 rtc = to_rtc_device(dev);
703
704 if (rtc) {
705 if (!try_module_get(rtc->owner)) {
706 put_device(dev);
707 rtc = NULL;
708 }
709 }
710
711 return rtc;
712}
713EXPORT_SYMBOL_GPL(rtc_class_open);
714
715void rtc_class_close(struct rtc_device *rtc)
716{
717 module_put(rtc->owner);
718 put_device(&rtc->dev);
719}
720EXPORT_SYMBOL_GPL(rtc_class_close);
721
722static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
723{
724 /*
725 * We always cancel the timer here first, because otherwise
726 * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
727 * when we manage to start the timer before the callback
728 * returns HRTIMER_RESTART.
729 *
730 * We cannot use hrtimer_cancel() here as a running callback
731 * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
732 * would spin forever.
733 */
734 if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
735 return -1;
736
737 if (enabled) {
738 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
739
740 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
741 }
742 return 0;
743}
744
745/**
746 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
747 * @rtc: the rtc device
748 * @enabled: true to enable periodic IRQs
749 * Context: any
750 *
751 * Note that rtc_irq_set_freq() should previously have been used to
752 * specify the desired frequency of periodic IRQ.
753 */
754int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
755{
756 int err = 0;
757
758 while (rtc_update_hrtimer(rtc, enabled) < 0)
759 cpu_relax();
760
761 rtc->pie_enabled = enabled;
762
763 trace_rtc_irq_set_state(enabled, err);
764 return err;
765}
766
767/**
768 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
769 * @rtc: the rtc device
770 * @freq: positive frequency
771 * Context: any
772 *
773 * Note that rtc_irq_set_state() is used to enable or disable the
774 * periodic IRQs.
775 */
776int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
777{
778 int err = 0;
779
780 if (freq <= 0 || freq > RTC_MAX_FREQ)
781 return -EINVAL;
782
783 rtc->irq_freq = freq;
784 while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
785 cpu_relax();
786
787 trace_rtc_irq_set_freq(freq, err);
788 return err;
789}
790
791/**
792 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
793 * @rtc: rtc device
794 * @timer: timer being added.
795 *
796 * Enqueues a timer onto the rtc devices timerqueue and sets
797 * the next alarm event appropriately.
798 *
799 * Sets the enabled bit on the added timer.
800 *
801 * Must hold ops_lock for proper serialization of timerqueue
802 */
803static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
804{
805 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
806 struct rtc_time tm;
807 ktime_t now;
808 int err;
809
810 err = __rtc_read_time(rtc, &tm);
811 if (err)
812 return err;
813
814 timer->enabled = 1;
815 now = rtc_tm_to_ktime(tm);
816
817 /* Skip over expired timers */
818 while (next) {
819 if (next->expires >= now)
820 break;
821 next = timerqueue_iterate_next(next);
822 }
823
824 timerqueue_add(&rtc->timerqueue, &timer->node);
825 trace_rtc_timer_enqueue(timer);
826 if (!next || ktime_before(timer->node.expires, next->expires)) {
827 struct rtc_wkalrm alarm;
828
829 alarm.time = rtc_ktime_to_tm(timer->node.expires);
830 alarm.enabled = 1;
831 err = __rtc_set_alarm(rtc, &alarm);
832 if (err == -ETIME) {
833 pm_stay_awake(rtc->dev.parent);
834 schedule_work(&rtc->irqwork);
835 } else if (err) {
836 timerqueue_del(&rtc->timerqueue, &timer->node);
837 trace_rtc_timer_dequeue(timer);
838 timer->enabled = 0;
839 return err;
840 }
841 }
842 return 0;
843}
844
845static void rtc_alarm_disable(struct rtc_device *rtc)
846{
847 if (!rtc->ops || !test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
848 return;
849
850 rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
851 trace_rtc_alarm_irq_enable(0, 0);
852}
853
854/**
855 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
856 * @rtc: rtc device
857 * @timer: timer being removed.
858 *
859 * Removes a timer onto the rtc devices timerqueue and sets
860 * the next alarm event appropriately.
861 *
862 * Clears the enabled bit on the removed timer.
863 *
864 * Must hold ops_lock for proper serialization of timerqueue
865 */
866static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
867{
868 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
869
870 timerqueue_del(&rtc->timerqueue, &timer->node);
871 trace_rtc_timer_dequeue(timer);
872 timer->enabled = 0;
873 if (next == &timer->node) {
874 struct rtc_wkalrm alarm;
875 int err;
876
877 next = timerqueue_getnext(&rtc->timerqueue);
878 if (!next) {
879 rtc_alarm_disable(rtc);
880 return;
881 }
882 alarm.time = rtc_ktime_to_tm(next->expires);
883 alarm.enabled = 1;
884 err = __rtc_set_alarm(rtc, &alarm);
885 if (err == -ETIME) {
886 pm_stay_awake(rtc->dev.parent);
887 schedule_work(&rtc->irqwork);
888 }
889 }
890}
891
892/**
893 * rtc_timer_do_work - Expires rtc timers
894 * @work: work item
895 *
896 * Expires rtc timers. Reprograms next alarm event if needed.
897 * Called via worktask.
898 *
899 * Serializes access to timerqueue via ops_lock mutex
900 */
901void rtc_timer_do_work(struct work_struct *work)
902{
903 struct rtc_timer *timer;
904 struct timerqueue_node *next;
905 ktime_t now;
906 struct rtc_time tm;
907 int err;
908
909 struct rtc_device *rtc =
910 container_of(work, struct rtc_device, irqwork);
911
912 mutex_lock(&rtc->ops_lock);
913again:
914 err = __rtc_read_time(rtc, &tm);
915 if (err) {
916 mutex_unlock(&rtc->ops_lock);
917 return;
918 }
919 now = rtc_tm_to_ktime(tm);
920 while ((next = timerqueue_getnext(&rtc->timerqueue))) {
921 if (next->expires > now)
922 break;
923
924 /* expire timer */
925 timer = container_of(next, struct rtc_timer, node);
926 timerqueue_del(&rtc->timerqueue, &timer->node);
927 trace_rtc_timer_dequeue(timer);
928 timer->enabled = 0;
929 if (timer->func)
930 timer->func(timer->rtc);
931
932 trace_rtc_timer_fired(timer);
933 /* Re-add/fwd periodic timers */
934 if (ktime_to_ns(timer->period)) {
935 timer->node.expires = ktime_add(timer->node.expires,
936 timer->period);
937 timer->enabled = 1;
938 timerqueue_add(&rtc->timerqueue, &timer->node);
939 trace_rtc_timer_enqueue(timer);
940 }
941 }
942
943 /* Set next alarm */
944 if (next) {
945 struct rtc_wkalrm alarm;
946 int err;
947 int retry = 3;
948
949 alarm.time = rtc_ktime_to_tm(next->expires);
950 alarm.enabled = 1;
951reprogram:
952 err = __rtc_set_alarm(rtc, &alarm);
953 if (err == -ETIME) {
954 goto again;
955 } else if (err) {
956 if (retry-- > 0)
957 goto reprogram;
958
959 timer = container_of(next, struct rtc_timer, node);
960 timerqueue_del(&rtc->timerqueue, &timer->node);
961 trace_rtc_timer_dequeue(timer);
962 timer->enabled = 0;
963 dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
964 goto again;
965 }
966 } else {
967 rtc_alarm_disable(rtc);
968 }
969
970 pm_relax(rtc->dev.parent);
971 mutex_unlock(&rtc->ops_lock);
972}
973
974/* rtc_timer_init - Initializes an rtc_timer
975 * @timer: timer to be intiialized
976 * @f: function pointer to be called when timer fires
977 * @rtc: pointer to the rtc_device
978 *
979 * Kernel interface to initializing an rtc_timer.
980 */
981void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
982 struct rtc_device *rtc)
983{
984 timerqueue_init(&timer->node);
985 timer->enabled = 0;
986 timer->func = f;
987 timer->rtc = rtc;
988}
989
990/* rtc_timer_start - Sets an rtc_timer to fire in the future
991 * @ rtc: rtc device to be used
992 * @ timer: timer being set
993 * @ expires: time at which to expire the timer
994 * @ period: period that the timer will recur
995 *
996 * Kernel interface to set an rtc_timer
997 */
998int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
999 ktime_t expires, ktime_t period)
1000{
1001 int ret = 0;
1002
1003 mutex_lock(&rtc->ops_lock);
1004 if (timer->enabled)
1005 rtc_timer_remove(rtc, timer);
1006
1007 timer->node.expires = expires;
1008 timer->period = period;
1009
1010 ret = rtc_timer_enqueue(rtc, timer);
1011
1012 mutex_unlock(&rtc->ops_lock);
1013 return ret;
1014}
1015
1016/* rtc_timer_cancel - Stops an rtc_timer
1017 * @ rtc: rtc device to be used
1018 * @ timer: timer being set
1019 *
1020 * Kernel interface to cancel an rtc_timer
1021 */
1022void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1023{
1024 mutex_lock(&rtc->ops_lock);
1025 if (timer->enabled)
1026 rtc_timer_remove(rtc, timer);
1027 mutex_unlock(&rtc->ops_lock);
1028}
1029
1030/**
1031 * rtc_read_offset - Read the amount of rtc offset in parts per billion
1032 * @rtc: rtc device to be used
1033 * @offset: the offset in parts per billion
1034 *
1035 * see below for details.
1036 *
1037 * Kernel interface to read rtc clock offset
1038 * Returns 0 on success, or a negative number on error.
1039 * If read_offset() is not implemented for the rtc, return -EINVAL
1040 */
1041int rtc_read_offset(struct rtc_device *rtc, long *offset)
1042{
1043 int ret;
1044
1045 if (!rtc->ops)
1046 return -ENODEV;
1047
1048 if (!rtc->ops->read_offset)
1049 return -EINVAL;
1050
1051 mutex_lock(&rtc->ops_lock);
1052 ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1053 mutex_unlock(&rtc->ops_lock);
1054
1055 trace_rtc_read_offset(*offset, ret);
1056 return ret;
1057}
1058
1059/**
1060 * rtc_set_offset - Adjusts the duration of the average second
1061 * @rtc: rtc device to be used
1062 * @offset: the offset in parts per billion
1063 *
1064 * Some rtc's allow an adjustment to the average duration of a second
1065 * to compensate for differences in the actual clock rate due to temperature,
1066 * the crystal, capacitor, etc.
1067 *
1068 * The adjustment applied is as follows:
1069 * t = t0 * (1 + offset * 1e-9)
1070 * where t0 is the measured length of 1 RTC second with offset = 0
1071 *
1072 * Kernel interface to adjust an rtc clock offset.
1073 * Return 0 on success, or a negative number on error.
1074 * If the rtc offset is not setable (or not implemented), return -EINVAL
1075 */
1076int rtc_set_offset(struct rtc_device *rtc, long offset)
1077{
1078 int ret;
1079
1080 if (!rtc->ops)
1081 return -ENODEV;
1082
1083 if (!rtc->ops->set_offset)
1084 return -EINVAL;
1085
1086 mutex_lock(&rtc->ops_lock);
1087 ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1088 mutex_unlock(&rtc->ops_lock);
1089
1090 trace_rtc_set_offset(offset, ret);
1091 return ret;
1092}
1/*
2 * RTC subsystem, interface functions
3 *
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
6 *
7 * based on arch/arm/common/rtctime.c
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12*/
13
14#include <linux/rtc.h>
15#include <linux/sched.h>
16#include <linux/module.h>
17#include <linux/log2.h>
18#include <linux/workqueue.h>
19
20#define CREATE_TRACE_POINTS
21#include <trace/events/rtc.h>
22
23static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
24static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
25
26static void rtc_add_offset(struct rtc_device *rtc, struct rtc_time *tm)
27{
28 time64_t secs;
29
30 if (!rtc->offset_secs)
31 return;
32
33 secs = rtc_tm_to_time64(tm);
34
35 /*
36 * Since the reading time values from RTC device are always in the RTC
37 * original valid range, but we need to skip the overlapped region
38 * between expanded range and original range, which is no need to add
39 * the offset.
40 */
41 if ((rtc->start_secs > rtc->range_min && secs >= rtc->start_secs) ||
42 (rtc->start_secs < rtc->range_min &&
43 secs <= (rtc->start_secs + rtc->range_max - rtc->range_min)))
44 return;
45
46 rtc_time64_to_tm(secs + rtc->offset_secs, tm);
47}
48
49static void rtc_subtract_offset(struct rtc_device *rtc, struct rtc_time *tm)
50{
51 time64_t secs;
52
53 if (!rtc->offset_secs)
54 return;
55
56 secs = rtc_tm_to_time64(tm);
57
58 /*
59 * If the setting time values are in the valid range of RTC hardware
60 * device, then no need to subtract the offset when setting time to RTC
61 * device. Otherwise we need to subtract the offset to make the time
62 * values are valid for RTC hardware device.
63 */
64 if (secs >= rtc->range_min && secs <= rtc->range_max)
65 return;
66
67 rtc_time64_to_tm(secs - rtc->offset_secs, tm);
68}
69
70static int rtc_valid_range(struct rtc_device *rtc, struct rtc_time *tm)
71{
72 if (rtc->range_min != rtc->range_max) {
73 time64_t time = rtc_tm_to_time64(tm);
74 time64_t range_min = rtc->set_start_time ? rtc->start_secs :
75 rtc->range_min;
76 time64_t range_max = rtc->set_start_time ?
77 (rtc->start_secs + rtc->range_max - rtc->range_min) :
78 rtc->range_max;
79
80 if (time < range_min || time > range_max)
81 return -ERANGE;
82 }
83
84 return 0;
85}
86
87static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
88{
89 int err;
90 if (!rtc->ops)
91 err = -ENODEV;
92 else if (!rtc->ops->read_time)
93 err = -EINVAL;
94 else {
95 memset(tm, 0, sizeof(struct rtc_time));
96 err = rtc->ops->read_time(rtc->dev.parent, tm);
97 if (err < 0) {
98 dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
99 err);
100 return err;
101 }
102
103 rtc_add_offset(rtc, tm);
104
105 err = rtc_valid_tm(tm);
106 if (err < 0)
107 dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
108 }
109 return err;
110}
111
112int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
113{
114 int err;
115
116 err = mutex_lock_interruptible(&rtc->ops_lock);
117 if (err)
118 return err;
119
120 err = __rtc_read_time(rtc, tm);
121 mutex_unlock(&rtc->ops_lock);
122
123 trace_rtc_read_time(rtc_tm_to_time64(tm), err);
124 return err;
125}
126EXPORT_SYMBOL_GPL(rtc_read_time);
127
128int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
129{
130 int err;
131
132 err = rtc_valid_tm(tm);
133 if (err != 0)
134 return err;
135
136 err = rtc_valid_range(rtc, tm);
137 if (err)
138 return err;
139
140 rtc_subtract_offset(rtc, tm);
141
142 err = mutex_lock_interruptible(&rtc->ops_lock);
143 if (err)
144 return err;
145
146 if (!rtc->ops)
147 err = -ENODEV;
148 else if (rtc->ops->set_time)
149 err = rtc->ops->set_time(rtc->dev.parent, tm);
150 else if (rtc->ops->set_mmss64) {
151 time64_t secs64 = rtc_tm_to_time64(tm);
152
153 err = rtc->ops->set_mmss64(rtc->dev.parent, secs64);
154 } else if (rtc->ops->set_mmss) {
155 time64_t secs64 = rtc_tm_to_time64(tm);
156 err = rtc->ops->set_mmss(rtc->dev.parent, secs64);
157 } else
158 err = -EINVAL;
159
160 pm_stay_awake(rtc->dev.parent);
161 mutex_unlock(&rtc->ops_lock);
162 /* A timer might have just expired */
163 schedule_work(&rtc->irqwork);
164
165 trace_rtc_set_time(rtc_tm_to_time64(tm), err);
166 return err;
167}
168EXPORT_SYMBOL_GPL(rtc_set_time);
169
170static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
171{
172 int err;
173
174 err = mutex_lock_interruptible(&rtc->ops_lock);
175 if (err)
176 return err;
177
178 if (rtc->ops == NULL)
179 err = -ENODEV;
180 else if (!rtc->ops->read_alarm)
181 err = -EINVAL;
182 else {
183 alarm->enabled = 0;
184 alarm->pending = 0;
185 alarm->time.tm_sec = -1;
186 alarm->time.tm_min = -1;
187 alarm->time.tm_hour = -1;
188 alarm->time.tm_mday = -1;
189 alarm->time.tm_mon = -1;
190 alarm->time.tm_year = -1;
191 alarm->time.tm_wday = -1;
192 alarm->time.tm_yday = -1;
193 alarm->time.tm_isdst = -1;
194 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
195 }
196
197 mutex_unlock(&rtc->ops_lock);
198
199 trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
200 return err;
201}
202
203int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
204{
205 int err;
206 struct rtc_time before, now;
207 int first_time = 1;
208 time64_t t_now, t_alm;
209 enum { none, day, month, year } missing = none;
210 unsigned days;
211
212 /* The lower level RTC driver may return -1 in some fields,
213 * creating invalid alarm->time values, for reasons like:
214 *
215 * - The hardware may not be capable of filling them in;
216 * many alarms match only on time-of-day fields, not
217 * day/month/year calendar data.
218 *
219 * - Some hardware uses illegal values as "wildcard" match
220 * values, which non-Linux firmware (like a BIOS) may try
221 * to set up as e.g. "alarm 15 minutes after each hour".
222 * Linux uses only oneshot alarms.
223 *
224 * When we see that here, we deal with it by using values from
225 * a current RTC timestamp for any missing (-1) values. The
226 * RTC driver prevents "periodic alarm" modes.
227 *
228 * But this can be racey, because some fields of the RTC timestamp
229 * may have wrapped in the interval since we read the RTC alarm,
230 * which would lead to us inserting inconsistent values in place
231 * of the -1 fields.
232 *
233 * Reading the alarm and timestamp in the reverse sequence
234 * would have the same race condition, and not solve the issue.
235 *
236 * So, we must first read the RTC timestamp,
237 * then read the RTC alarm value,
238 * and then read a second RTC timestamp.
239 *
240 * If any fields of the second timestamp have changed
241 * when compared with the first timestamp, then we know
242 * our timestamp may be inconsistent with that used by
243 * the low-level rtc_read_alarm_internal() function.
244 *
245 * So, when the two timestamps disagree, we just loop and do
246 * the process again to get a fully consistent set of values.
247 *
248 * This could all instead be done in the lower level driver,
249 * but since more than one lower level RTC implementation needs it,
250 * then it's probably best best to do it here instead of there..
251 */
252
253 /* Get the "before" timestamp */
254 err = rtc_read_time(rtc, &before);
255 if (err < 0)
256 return err;
257 do {
258 if (!first_time)
259 memcpy(&before, &now, sizeof(struct rtc_time));
260 first_time = 0;
261
262 /* get the RTC alarm values, which may be incomplete */
263 err = rtc_read_alarm_internal(rtc, alarm);
264 if (err)
265 return err;
266
267 /* full-function RTCs won't have such missing fields */
268 if (rtc_valid_tm(&alarm->time) == 0)
269 return 0;
270
271 /* get the "after" timestamp, to detect wrapped fields */
272 err = rtc_read_time(rtc, &now);
273 if (err < 0)
274 return err;
275
276 /* note that tm_sec is a "don't care" value here: */
277 } while ( before.tm_min != now.tm_min
278 || before.tm_hour != now.tm_hour
279 || before.tm_mon != now.tm_mon
280 || before.tm_year != now.tm_year);
281
282 /* Fill in the missing alarm fields using the timestamp; we
283 * know there's at least one since alarm->time is invalid.
284 */
285 if (alarm->time.tm_sec == -1)
286 alarm->time.tm_sec = now.tm_sec;
287 if (alarm->time.tm_min == -1)
288 alarm->time.tm_min = now.tm_min;
289 if (alarm->time.tm_hour == -1)
290 alarm->time.tm_hour = now.tm_hour;
291
292 /* For simplicity, only support date rollover for now */
293 if (alarm->time.tm_mday < 1 || alarm->time.tm_mday > 31) {
294 alarm->time.tm_mday = now.tm_mday;
295 missing = day;
296 }
297 if ((unsigned)alarm->time.tm_mon >= 12) {
298 alarm->time.tm_mon = now.tm_mon;
299 if (missing == none)
300 missing = month;
301 }
302 if (alarm->time.tm_year == -1) {
303 alarm->time.tm_year = now.tm_year;
304 if (missing == none)
305 missing = year;
306 }
307
308 /* Can't proceed if alarm is still invalid after replacing
309 * missing fields.
310 */
311 err = rtc_valid_tm(&alarm->time);
312 if (err)
313 goto done;
314
315 /* with luck, no rollover is needed */
316 t_now = rtc_tm_to_time64(&now);
317 t_alm = rtc_tm_to_time64(&alarm->time);
318 if (t_now < t_alm)
319 goto done;
320
321 switch (missing) {
322
323 /* 24 hour rollover ... if it's now 10am Monday, an alarm that
324 * that will trigger at 5am will do so at 5am Tuesday, which
325 * could also be in the next month or year. This is a common
326 * case, especially for PCs.
327 */
328 case day:
329 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
330 t_alm += 24 * 60 * 60;
331 rtc_time64_to_tm(t_alm, &alarm->time);
332 break;
333
334 /* Month rollover ... if it's the 31th, an alarm on the 3rd will
335 * be next month. An alarm matching on the 30th, 29th, or 28th
336 * may end up in the month after that! Many newer PCs support
337 * this type of alarm.
338 */
339 case month:
340 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
341 do {
342 if (alarm->time.tm_mon < 11)
343 alarm->time.tm_mon++;
344 else {
345 alarm->time.tm_mon = 0;
346 alarm->time.tm_year++;
347 }
348 days = rtc_month_days(alarm->time.tm_mon,
349 alarm->time.tm_year);
350 } while (days < alarm->time.tm_mday);
351 break;
352
353 /* Year rollover ... easy except for leap years! */
354 case year:
355 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
356 do {
357 alarm->time.tm_year++;
358 } while (!is_leap_year(alarm->time.tm_year + 1900)
359 && rtc_valid_tm(&alarm->time) != 0);
360 break;
361
362 default:
363 dev_warn(&rtc->dev, "alarm rollover not handled\n");
364 }
365
366 err = rtc_valid_tm(&alarm->time);
367
368done:
369 if (err) {
370 dev_warn(&rtc->dev, "invalid alarm value: %d-%d-%d %d:%d:%d\n",
371 alarm->time.tm_year + 1900, alarm->time.tm_mon + 1,
372 alarm->time.tm_mday, alarm->time.tm_hour, alarm->time.tm_min,
373 alarm->time.tm_sec);
374 }
375
376 return err;
377}
378
379int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
380{
381 int err;
382
383 err = mutex_lock_interruptible(&rtc->ops_lock);
384 if (err)
385 return err;
386 if (rtc->ops == NULL)
387 err = -ENODEV;
388 else if (!rtc->ops->read_alarm)
389 err = -EINVAL;
390 else {
391 memset(alarm, 0, sizeof(struct rtc_wkalrm));
392 alarm->enabled = rtc->aie_timer.enabled;
393 alarm->time = rtc_ktime_to_tm(rtc->aie_timer.node.expires);
394 }
395 mutex_unlock(&rtc->ops_lock);
396
397 trace_rtc_read_alarm(rtc_tm_to_time64(&alarm->time), err);
398 return err;
399}
400EXPORT_SYMBOL_GPL(rtc_read_alarm);
401
402static int __rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
403{
404 struct rtc_time tm;
405 time64_t now, scheduled;
406 int err;
407
408 err = rtc_valid_tm(&alarm->time);
409 if (err)
410 return err;
411
412 rtc_subtract_offset(rtc, &alarm->time);
413 scheduled = rtc_tm_to_time64(&alarm->time);
414
415 /* Make sure we're not setting alarms in the past */
416 err = __rtc_read_time(rtc, &tm);
417 if (err)
418 return err;
419 now = rtc_tm_to_time64(&tm);
420 if (scheduled <= now)
421 return -ETIME;
422 /*
423 * XXX - We just checked to make sure the alarm time is not
424 * in the past, but there is still a race window where if
425 * the is alarm set for the next second and the second ticks
426 * over right here, before we set the alarm.
427 */
428
429 if (!rtc->ops)
430 err = -ENODEV;
431 else if (!rtc->ops->set_alarm)
432 err = -EINVAL;
433 else
434 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
435
436 trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
437 return err;
438}
439
440int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
441{
442 int err;
443
444 err = rtc_valid_tm(&alarm->time);
445 if (err != 0)
446 return err;
447
448 err = rtc_valid_range(rtc, &alarm->time);
449 if (err)
450 return err;
451
452 err = mutex_lock_interruptible(&rtc->ops_lock);
453 if (err)
454 return err;
455 if (rtc->aie_timer.enabled)
456 rtc_timer_remove(rtc, &rtc->aie_timer);
457
458 rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
459 rtc->aie_timer.period = 0;
460 if (alarm->enabled)
461 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
462
463 mutex_unlock(&rtc->ops_lock);
464
465 rtc_add_offset(rtc, &alarm->time);
466 return err;
467}
468EXPORT_SYMBOL_GPL(rtc_set_alarm);
469
470/* Called once per device from rtc_device_register */
471int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
472{
473 int err;
474 struct rtc_time now;
475
476 err = rtc_valid_tm(&alarm->time);
477 if (err != 0)
478 return err;
479
480 err = rtc_read_time(rtc, &now);
481 if (err)
482 return err;
483
484 err = mutex_lock_interruptible(&rtc->ops_lock);
485 if (err)
486 return err;
487
488 rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
489 rtc->aie_timer.period = 0;
490
491 /* Alarm has to be enabled & in the future for us to enqueue it */
492 if (alarm->enabled && (rtc_tm_to_ktime(now) <
493 rtc->aie_timer.node.expires)) {
494
495 rtc->aie_timer.enabled = 1;
496 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
497 trace_rtc_timer_enqueue(&rtc->aie_timer);
498 }
499 mutex_unlock(&rtc->ops_lock);
500 return err;
501}
502EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
503
504int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
505{
506 int err = mutex_lock_interruptible(&rtc->ops_lock);
507 if (err)
508 return err;
509
510 if (rtc->aie_timer.enabled != enabled) {
511 if (enabled)
512 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
513 else
514 rtc_timer_remove(rtc, &rtc->aie_timer);
515 }
516
517 if (err)
518 /* nothing */;
519 else if (!rtc->ops)
520 err = -ENODEV;
521 else if (!rtc->ops->alarm_irq_enable)
522 err = -EINVAL;
523 else
524 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
525
526 mutex_unlock(&rtc->ops_lock);
527
528 trace_rtc_alarm_irq_enable(enabled, err);
529 return err;
530}
531EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
532
533int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
534{
535 int err = mutex_lock_interruptible(&rtc->ops_lock);
536 if (err)
537 return err;
538
539#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
540 if (enabled == 0 && rtc->uie_irq_active) {
541 mutex_unlock(&rtc->ops_lock);
542 return rtc_dev_update_irq_enable_emul(rtc, 0);
543 }
544#endif
545 /* make sure we're changing state */
546 if (rtc->uie_rtctimer.enabled == enabled)
547 goto out;
548
549 if (rtc->uie_unsupported) {
550 err = -EINVAL;
551 goto out;
552 }
553
554 if (enabled) {
555 struct rtc_time tm;
556 ktime_t now, onesec;
557
558 __rtc_read_time(rtc, &tm);
559 onesec = ktime_set(1, 0);
560 now = rtc_tm_to_ktime(tm);
561 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
562 rtc->uie_rtctimer.period = ktime_set(1, 0);
563 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
564 } else
565 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
566
567out:
568 mutex_unlock(&rtc->ops_lock);
569#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
570 /*
571 * Enable emulation if the driver did not provide
572 * the update_irq_enable function pointer or if returned
573 * -EINVAL to signal that it has been configured without
574 * interrupts or that are not available at the moment.
575 */
576 if (err == -EINVAL)
577 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
578#endif
579 return err;
580
581}
582EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
583
584
585/**
586 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
587 * @rtc: pointer to the rtc device
588 *
589 * This function is called when an AIE, UIE or PIE mode interrupt
590 * has occurred (or been emulated).
591 *
592 * Triggers the registered irq_task function callback.
593 */
594void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
595{
596 unsigned long flags;
597
598 /* mark one irq of the appropriate mode */
599 spin_lock_irqsave(&rtc->irq_lock, flags);
600 rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
601 spin_unlock_irqrestore(&rtc->irq_lock, flags);
602
603 /* call the task func */
604 spin_lock_irqsave(&rtc->irq_task_lock, flags);
605 if (rtc->irq_task)
606 rtc->irq_task->func(rtc->irq_task->private_data);
607 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
608
609 wake_up_interruptible(&rtc->irq_queue);
610 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
611}
612
613
614/**
615 * rtc_aie_update_irq - AIE mode rtctimer hook
616 * @private: pointer to the rtc_device
617 *
618 * This functions is called when the aie_timer expires.
619 */
620void rtc_aie_update_irq(void *private)
621{
622 struct rtc_device *rtc = (struct rtc_device *)private;
623 rtc_handle_legacy_irq(rtc, 1, RTC_AF);
624}
625
626
627/**
628 * rtc_uie_update_irq - UIE mode rtctimer hook
629 * @private: pointer to the rtc_device
630 *
631 * This functions is called when the uie_timer expires.
632 */
633void rtc_uie_update_irq(void *private)
634{
635 struct rtc_device *rtc = (struct rtc_device *)private;
636 rtc_handle_legacy_irq(rtc, 1, RTC_UF);
637}
638
639
640/**
641 * rtc_pie_update_irq - PIE mode hrtimer hook
642 * @timer: pointer to the pie mode hrtimer
643 *
644 * This function is used to emulate PIE mode interrupts
645 * using an hrtimer. This function is called when the periodic
646 * hrtimer expires.
647 */
648enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
649{
650 struct rtc_device *rtc;
651 ktime_t period;
652 int count;
653 rtc = container_of(timer, struct rtc_device, pie_timer);
654
655 period = NSEC_PER_SEC / rtc->irq_freq;
656 count = hrtimer_forward_now(timer, period);
657
658 rtc_handle_legacy_irq(rtc, count, RTC_PF);
659
660 return HRTIMER_RESTART;
661}
662
663/**
664 * rtc_update_irq - Triggered when a RTC interrupt occurs.
665 * @rtc: the rtc device
666 * @num: how many irqs are being reported (usually one)
667 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
668 * Context: any
669 */
670void rtc_update_irq(struct rtc_device *rtc,
671 unsigned long num, unsigned long events)
672{
673 if (IS_ERR_OR_NULL(rtc))
674 return;
675
676 pm_stay_awake(rtc->dev.parent);
677 schedule_work(&rtc->irqwork);
678}
679EXPORT_SYMBOL_GPL(rtc_update_irq);
680
681static int __rtc_match(struct device *dev, const void *data)
682{
683 const char *name = data;
684
685 if (strcmp(dev_name(dev), name) == 0)
686 return 1;
687 return 0;
688}
689
690struct rtc_device *rtc_class_open(const char *name)
691{
692 struct device *dev;
693 struct rtc_device *rtc = NULL;
694
695 dev = class_find_device(rtc_class, NULL, name, __rtc_match);
696 if (dev)
697 rtc = to_rtc_device(dev);
698
699 if (rtc) {
700 if (!try_module_get(rtc->owner)) {
701 put_device(dev);
702 rtc = NULL;
703 }
704 }
705
706 return rtc;
707}
708EXPORT_SYMBOL_GPL(rtc_class_open);
709
710void rtc_class_close(struct rtc_device *rtc)
711{
712 module_put(rtc->owner);
713 put_device(&rtc->dev);
714}
715EXPORT_SYMBOL_GPL(rtc_class_close);
716
717int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
718{
719 int retval = -EBUSY;
720
721 if (task == NULL || task->func == NULL)
722 return -EINVAL;
723
724 /* Cannot register while the char dev is in use */
725 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
726 return -EBUSY;
727
728 spin_lock_irq(&rtc->irq_task_lock);
729 if (rtc->irq_task == NULL) {
730 rtc->irq_task = task;
731 retval = 0;
732 }
733 spin_unlock_irq(&rtc->irq_task_lock);
734
735 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
736
737 return retval;
738}
739EXPORT_SYMBOL_GPL(rtc_irq_register);
740
741void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
742{
743 spin_lock_irq(&rtc->irq_task_lock);
744 if (rtc->irq_task == task)
745 rtc->irq_task = NULL;
746 spin_unlock_irq(&rtc->irq_task_lock);
747}
748EXPORT_SYMBOL_GPL(rtc_irq_unregister);
749
750static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
751{
752 /*
753 * We always cancel the timer here first, because otherwise
754 * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
755 * when we manage to start the timer before the callback
756 * returns HRTIMER_RESTART.
757 *
758 * We cannot use hrtimer_cancel() here as a running callback
759 * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
760 * would spin forever.
761 */
762 if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
763 return -1;
764
765 if (enabled) {
766 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
767
768 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
769 }
770 return 0;
771}
772
773/**
774 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
775 * @rtc: the rtc device
776 * @task: currently registered with rtc_irq_register()
777 * @enabled: true to enable periodic IRQs
778 * Context: any
779 *
780 * Note that rtc_irq_set_freq() should previously have been used to
781 * specify the desired frequency of periodic IRQ task->func() callbacks.
782 */
783int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
784{
785 int err = 0;
786 unsigned long flags;
787
788retry:
789 spin_lock_irqsave(&rtc->irq_task_lock, flags);
790 if (rtc->irq_task != NULL && task == NULL)
791 err = -EBUSY;
792 else if (rtc->irq_task != task)
793 err = -EACCES;
794 else {
795 if (rtc_update_hrtimer(rtc, enabled) < 0) {
796 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
797 cpu_relax();
798 goto retry;
799 }
800 rtc->pie_enabled = enabled;
801 }
802 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
803
804 trace_rtc_irq_set_state(enabled, err);
805 return err;
806}
807EXPORT_SYMBOL_GPL(rtc_irq_set_state);
808
809/**
810 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
811 * @rtc: the rtc device
812 * @task: currently registered with rtc_irq_register()
813 * @freq: positive frequency with which task->func() will be called
814 * Context: any
815 *
816 * Note that rtc_irq_set_state() is used to enable or disable the
817 * periodic IRQs.
818 */
819int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
820{
821 int err = 0;
822 unsigned long flags;
823
824 if (freq <= 0 || freq > RTC_MAX_FREQ)
825 return -EINVAL;
826retry:
827 spin_lock_irqsave(&rtc->irq_task_lock, flags);
828 if (rtc->irq_task != NULL && task == NULL)
829 err = -EBUSY;
830 else if (rtc->irq_task != task)
831 err = -EACCES;
832 else {
833 rtc->irq_freq = freq;
834 if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
835 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
836 cpu_relax();
837 goto retry;
838 }
839 }
840 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
841
842 trace_rtc_irq_set_freq(freq, err);
843 return err;
844}
845EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
846
847/**
848 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
849 * @rtc rtc device
850 * @timer timer being added.
851 *
852 * Enqueues a timer onto the rtc devices timerqueue and sets
853 * the next alarm event appropriately.
854 *
855 * Sets the enabled bit on the added timer.
856 *
857 * Must hold ops_lock for proper serialization of timerqueue
858 */
859static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
860{
861 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
862 struct rtc_time tm;
863 ktime_t now;
864
865 timer->enabled = 1;
866 __rtc_read_time(rtc, &tm);
867 now = rtc_tm_to_ktime(tm);
868
869 /* Skip over expired timers */
870 while (next) {
871 if (next->expires >= now)
872 break;
873 next = timerqueue_iterate_next(next);
874 }
875
876 timerqueue_add(&rtc->timerqueue, &timer->node);
877 trace_rtc_timer_enqueue(timer);
878 if (!next || ktime_before(timer->node.expires, next->expires)) {
879 struct rtc_wkalrm alarm;
880 int err;
881 alarm.time = rtc_ktime_to_tm(timer->node.expires);
882 alarm.enabled = 1;
883 err = __rtc_set_alarm(rtc, &alarm);
884 if (err == -ETIME) {
885 pm_stay_awake(rtc->dev.parent);
886 schedule_work(&rtc->irqwork);
887 } else if (err) {
888 timerqueue_del(&rtc->timerqueue, &timer->node);
889 trace_rtc_timer_dequeue(timer);
890 timer->enabled = 0;
891 return err;
892 }
893 }
894 return 0;
895}
896
897static void rtc_alarm_disable(struct rtc_device *rtc)
898{
899 if (!rtc->ops || !rtc->ops->alarm_irq_enable)
900 return;
901
902 rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
903 trace_rtc_alarm_irq_enable(0, 0);
904}
905
906/**
907 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
908 * @rtc rtc device
909 * @timer timer being removed.
910 *
911 * Removes a timer onto the rtc devices timerqueue and sets
912 * the next alarm event appropriately.
913 *
914 * Clears the enabled bit on the removed timer.
915 *
916 * Must hold ops_lock for proper serialization of timerqueue
917 */
918static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
919{
920 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
921 timerqueue_del(&rtc->timerqueue, &timer->node);
922 trace_rtc_timer_dequeue(timer);
923 timer->enabled = 0;
924 if (next == &timer->node) {
925 struct rtc_wkalrm alarm;
926 int err;
927 next = timerqueue_getnext(&rtc->timerqueue);
928 if (!next) {
929 rtc_alarm_disable(rtc);
930 return;
931 }
932 alarm.time = rtc_ktime_to_tm(next->expires);
933 alarm.enabled = 1;
934 err = __rtc_set_alarm(rtc, &alarm);
935 if (err == -ETIME) {
936 pm_stay_awake(rtc->dev.parent);
937 schedule_work(&rtc->irqwork);
938 }
939 }
940}
941
942/**
943 * rtc_timer_do_work - Expires rtc timers
944 * @rtc rtc device
945 * @timer timer being removed.
946 *
947 * Expires rtc timers. Reprograms next alarm event if needed.
948 * Called via worktask.
949 *
950 * Serializes access to timerqueue via ops_lock mutex
951 */
952void rtc_timer_do_work(struct work_struct *work)
953{
954 struct rtc_timer *timer;
955 struct timerqueue_node *next;
956 ktime_t now;
957 struct rtc_time tm;
958
959 struct rtc_device *rtc =
960 container_of(work, struct rtc_device, irqwork);
961
962 mutex_lock(&rtc->ops_lock);
963again:
964 __rtc_read_time(rtc, &tm);
965 now = rtc_tm_to_ktime(tm);
966 while ((next = timerqueue_getnext(&rtc->timerqueue))) {
967 if (next->expires > now)
968 break;
969
970 /* expire timer */
971 timer = container_of(next, struct rtc_timer, node);
972 timerqueue_del(&rtc->timerqueue, &timer->node);
973 trace_rtc_timer_dequeue(timer);
974 timer->enabled = 0;
975 if (timer->task.func)
976 timer->task.func(timer->task.private_data);
977
978 trace_rtc_timer_fired(timer);
979 /* Re-add/fwd periodic timers */
980 if (ktime_to_ns(timer->period)) {
981 timer->node.expires = ktime_add(timer->node.expires,
982 timer->period);
983 timer->enabled = 1;
984 timerqueue_add(&rtc->timerqueue, &timer->node);
985 trace_rtc_timer_enqueue(timer);
986 }
987 }
988
989 /* Set next alarm */
990 if (next) {
991 struct rtc_wkalrm alarm;
992 int err;
993 int retry = 3;
994
995 alarm.time = rtc_ktime_to_tm(next->expires);
996 alarm.enabled = 1;
997reprogram:
998 err = __rtc_set_alarm(rtc, &alarm);
999 if (err == -ETIME)
1000 goto again;
1001 else if (err) {
1002 if (retry-- > 0)
1003 goto reprogram;
1004
1005 timer = container_of(next, struct rtc_timer, node);
1006 timerqueue_del(&rtc->timerqueue, &timer->node);
1007 trace_rtc_timer_dequeue(timer);
1008 timer->enabled = 0;
1009 dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
1010 goto again;
1011 }
1012 } else
1013 rtc_alarm_disable(rtc);
1014
1015 pm_relax(rtc->dev.parent);
1016 mutex_unlock(&rtc->ops_lock);
1017}
1018
1019
1020/* rtc_timer_init - Initializes an rtc_timer
1021 * @timer: timer to be intiialized
1022 * @f: function pointer to be called when timer fires
1023 * @data: private data passed to function pointer
1024 *
1025 * Kernel interface to initializing an rtc_timer.
1026 */
1027void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
1028{
1029 timerqueue_init(&timer->node);
1030 timer->enabled = 0;
1031 timer->task.func = f;
1032 timer->task.private_data = data;
1033}
1034
1035/* rtc_timer_start - Sets an rtc_timer to fire in the future
1036 * @ rtc: rtc device to be used
1037 * @ timer: timer being set
1038 * @ expires: time at which to expire the timer
1039 * @ period: period that the timer will recur
1040 *
1041 * Kernel interface to set an rtc_timer
1042 */
1043int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
1044 ktime_t expires, ktime_t period)
1045{
1046 int ret = 0;
1047 mutex_lock(&rtc->ops_lock);
1048 if (timer->enabled)
1049 rtc_timer_remove(rtc, timer);
1050
1051 timer->node.expires = expires;
1052 timer->period = period;
1053
1054 ret = rtc_timer_enqueue(rtc, timer);
1055
1056 mutex_unlock(&rtc->ops_lock);
1057 return ret;
1058}
1059
1060/* rtc_timer_cancel - Stops an rtc_timer
1061 * @ rtc: rtc device to be used
1062 * @ timer: timer being set
1063 *
1064 * Kernel interface to cancel an rtc_timer
1065 */
1066void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1067{
1068 mutex_lock(&rtc->ops_lock);
1069 if (timer->enabled)
1070 rtc_timer_remove(rtc, timer);
1071 mutex_unlock(&rtc->ops_lock);
1072}
1073
1074/**
1075 * rtc_read_offset - Read the amount of rtc offset in parts per billion
1076 * @ rtc: rtc device to be used
1077 * @ offset: the offset in parts per billion
1078 *
1079 * see below for details.
1080 *
1081 * Kernel interface to read rtc clock offset
1082 * Returns 0 on success, or a negative number on error.
1083 * If read_offset() is not implemented for the rtc, return -EINVAL
1084 */
1085int rtc_read_offset(struct rtc_device *rtc, long *offset)
1086{
1087 int ret;
1088
1089 if (!rtc->ops)
1090 return -ENODEV;
1091
1092 if (!rtc->ops->read_offset)
1093 return -EINVAL;
1094
1095 mutex_lock(&rtc->ops_lock);
1096 ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1097 mutex_unlock(&rtc->ops_lock);
1098
1099 trace_rtc_read_offset(*offset, ret);
1100 return ret;
1101}
1102
1103/**
1104 * rtc_set_offset - Adjusts the duration of the average second
1105 * @ rtc: rtc device to be used
1106 * @ offset: the offset in parts per billion
1107 *
1108 * Some rtc's allow an adjustment to the average duration of a second
1109 * to compensate for differences in the actual clock rate due to temperature,
1110 * the crystal, capacitor, etc.
1111 *
1112 * The adjustment applied is as follows:
1113 * t = t0 * (1 + offset * 1e-9)
1114 * where t0 is the measured length of 1 RTC second with offset = 0
1115 *
1116 * Kernel interface to adjust an rtc clock offset.
1117 * Return 0 on success, or a negative number on error.
1118 * If the rtc offset is not setable (or not implemented), return -EINVAL
1119 */
1120int rtc_set_offset(struct rtc_device *rtc, long offset)
1121{
1122 int ret;
1123
1124 if (!rtc->ops)
1125 return -ENODEV;
1126
1127 if (!rtc->ops->set_offset)
1128 return -EINVAL;
1129
1130 mutex_lock(&rtc->ops_lock);
1131 ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1132 mutex_unlock(&rtc->ops_lock);
1133
1134 trace_rtc_set_offset(offset, ret);
1135 return ret;
1136}