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
20 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
21 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
22
rtc_add_offset(struct rtc_device * rtc,struct rtc_time * tm)23 static 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
rtc_subtract_offset(struct rtc_device * rtc,struct rtc_time * tm)46 static 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
rtc_valid_range(struct rtc_device * rtc,struct rtc_time * tm)67 static 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
__rtc_read_time(struct rtc_device * rtc,struct rtc_time * tm)84 static 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
rtc_read_time(struct rtc_device * rtc,struct rtc_time * tm)110 int 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 }
124 EXPORT_SYMBOL_GPL(rtc_read_time);
125
rtc_set_time(struct rtc_device * rtc,struct rtc_time * tm)126 int 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 }
176 EXPORT_SYMBOL_GPL(rtc_set_time);
177
rtc_read_alarm_internal(struct rtc_device * rtc,struct rtc_wkalrm * alarm)178 static 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(err?0:rtc_tm_to_time64(&alarm->time), err);
209 return err;
210 }
211
__rtc_read_alarm(struct rtc_device * rtc,struct rtc_wkalrm * alarm)212 int __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
377 done:
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
rtc_read_alarm(struct rtc_device * rtc,struct rtc_wkalrm * alarm)387 int 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 }
408 EXPORT_SYMBOL_GPL(rtc_read_alarm);
409
__rtc_set_alarm(struct rtc_device * rtc,struct rtc_wkalrm * alarm)410 static 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 /*
447 * Check for potential race described above. If the waiting for next
448 * second, and the second just ticked since the check above, either
449 *
450 * 1) It ticked after the alarm was set, and an alarm irq should be
451 * generated.
452 *
453 * 2) It ticked before the alarm was set, and alarm irq most likely will
454 * not be generated.
455 *
456 * While we cannot easily check for which of these two scenarios we
457 * are in, we can return -ETIME to signal that the timer has already
458 * expired, which is true in both cases.
459 */
460 if ((scheduled - now) <= 1) {
461 err = __rtc_read_time(rtc, &tm);
462 if (err)
463 return err;
464 now = rtc_tm_to_time64(&tm);
465 if (scheduled <= now)
466 return -ETIME;
467 }
468
469 trace_rtc_set_alarm(rtc_tm_to_time64(&alarm->time), err);
470 return err;
471 }
472
rtc_set_alarm(struct rtc_device * rtc,struct rtc_wkalrm * alarm)473 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
474 {
475 ktime_t alarm_time;
476 int err;
477
478 if (!rtc->ops)
479 return -ENODEV;
480 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features))
481 return -EINVAL;
482
483 err = rtc_valid_tm(&alarm->time);
484 if (err != 0)
485 return err;
486
487 err = rtc_valid_range(rtc, &alarm->time);
488 if (err)
489 return err;
490
491 err = mutex_lock_interruptible(&rtc->ops_lock);
492 if (err)
493 return err;
494 if (rtc->aie_timer.enabled)
495 rtc_timer_remove(rtc, &rtc->aie_timer);
496
497 alarm_time = rtc_tm_to_ktime(alarm->time);
498 /*
499 * Round down so we never miss a deadline, checking for past deadline is
500 * done in __rtc_set_alarm
501 */
502 if (test_bit(RTC_FEATURE_ALARM_RES_MINUTE, rtc->features))
503 alarm_time = ktime_sub_ns(alarm_time, (u64)alarm->time.tm_sec * NSEC_PER_SEC);
504
505 rtc->aie_timer.node.expires = alarm_time;
506 rtc->aie_timer.period = 0;
507 if (alarm->enabled)
508 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
509
510 mutex_unlock(&rtc->ops_lock);
511
512 return err;
513 }
514 EXPORT_SYMBOL_GPL(rtc_set_alarm);
515
516 /* Called once per device from rtc_device_register */
rtc_initialize_alarm(struct rtc_device * rtc,struct rtc_wkalrm * alarm)517 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
518 {
519 int err;
520 struct rtc_time now;
521
522 err = rtc_valid_tm(&alarm->time);
523 if (err != 0)
524 return err;
525
526 err = rtc_read_time(rtc, &now);
527 if (err)
528 return err;
529
530 err = mutex_lock_interruptible(&rtc->ops_lock);
531 if (err)
532 return err;
533
534 rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
535 rtc->aie_timer.period = 0;
536
537 /* Alarm has to be enabled & in the future for us to enqueue it */
538 if (alarm->enabled && (rtc_tm_to_ktime(now) <
539 rtc->aie_timer.node.expires)) {
540 rtc->aie_timer.enabled = 1;
541 timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
542 trace_rtc_timer_enqueue(&rtc->aie_timer);
543 }
544 mutex_unlock(&rtc->ops_lock);
545 return err;
546 }
547 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
548
rtc_alarm_irq_enable(struct rtc_device * rtc,unsigned int enabled)549 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
550 {
551 int err;
552
553 err = mutex_lock_interruptible(&rtc->ops_lock);
554 if (err)
555 return err;
556
557 if (rtc->aie_timer.enabled != enabled) {
558 if (enabled)
559 err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
560 else
561 rtc_timer_remove(rtc, &rtc->aie_timer);
562 }
563
564 if (err)
565 /* nothing */;
566 else if (!rtc->ops)
567 err = -ENODEV;
568 else if (!test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
569 err = -EINVAL;
570 else
571 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
572
573 mutex_unlock(&rtc->ops_lock);
574
575 trace_rtc_alarm_irq_enable(enabled, err);
576 return err;
577 }
578 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
579
rtc_update_irq_enable(struct rtc_device * rtc,unsigned int enabled)580 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
581 {
582 int err;
583
584 err = mutex_lock_interruptible(&rtc->ops_lock);
585 if (err)
586 return err;
587
588 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
589 if (enabled == 0 && rtc->uie_irq_active) {
590 mutex_unlock(&rtc->ops_lock);
591 return rtc_dev_update_irq_enable_emul(rtc, 0);
592 }
593 #endif
594 /* make sure we're changing state */
595 if (rtc->uie_rtctimer.enabled == enabled)
596 goto out;
597
598 if (!test_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features) ||
599 !test_bit(RTC_FEATURE_ALARM, rtc->features)) {
600 mutex_unlock(&rtc->ops_lock);
601 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
602 return rtc_dev_update_irq_enable_emul(rtc, enabled);
603 #else
604 return -EINVAL;
605 #endif
606 }
607
608 if (enabled) {
609 struct rtc_time tm;
610 ktime_t now, onesec;
611
612 err = __rtc_read_time(rtc, &tm);
613 if (err)
614 goto out;
615 onesec = ktime_set(1, 0);
616 now = rtc_tm_to_ktime(tm);
617 rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
618 rtc->uie_rtctimer.period = ktime_set(1, 0);
619 err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
620 if (!err && rtc->ops && rtc->ops->alarm_irq_enable)
621 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, 1);
622 if (err)
623 goto out;
624 } else {
625 rtc_timer_remove(rtc, &rtc->uie_rtctimer);
626 }
627
628 out:
629 mutex_unlock(&rtc->ops_lock);
630
631 return err;
632 }
633 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
634
635 /**
636 * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
637 * @rtc: pointer to the rtc device
638 * @num: number of occurence of the event
639 * @mode: type of the event, RTC_AF, RTC_UF of RTC_PF
640 *
641 * This function is called when an AIE, UIE or PIE mode interrupt
642 * has occurred (or been emulated).
643 *
644 */
rtc_handle_legacy_irq(struct rtc_device * rtc,int num,int mode)645 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
646 {
647 unsigned long flags;
648
649 /* mark one irq of the appropriate mode */
650 spin_lock_irqsave(&rtc->irq_lock, flags);
651 rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF | mode);
652 spin_unlock_irqrestore(&rtc->irq_lock, flags);
653
654 wake_up_interruptible(&rtc->irq_queue);
655 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
656 }
657
658 /**
659 * rtc_aie_update_irq - AIE mode rtctimer hook
660 * @rtc: pointer to the rtc_device
661 *
662 * This functions is called when the aie_timer expires.
663 */
rtc_aie_update_irq(struct rtc_device * rtc)664 void rtc_aie_update_irq(struct rtc_device *rtc)
665 {
666 rtc_handle_legacy_irq(rtc, 1, RTC_AF);
667 }
668
669 /**
670 * rtc_uie_update_irq - UIE mode rtctimer hook
671 * @rtc: pointer to the rtc_device
672 *
673 * This functions is called when the uie_timer expires.
674 */
rtc_uie_update_irq(struct rtc_device * rtc)675 void rtc_uie_update_irq(struct rtc_device *rtc)
676 {
677 rtc_handle_legacy_irq(rtc, 1, RTC_UF);
678 }
679
680 /**
681 * rtc_pie_update_irq - PIE mode hrtimer hook
682 * @timer: pointer to the pie mode hrtimer
683 *
684 * This function is used to emulate PIE mode interrupts
685 * using an hrtimer. This function is called when the periodic
686 * hrtimer expires.
687 */
rtc_pie_update_irq(struct hrtimer * timer)688 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
689 {
690 struct rtc_device *rtc;
691 ktime_t period;
692 u64 count;
693
694 rtc = container_of(timer, struct rtc_device, pie_timer);
695
696 period = NSEC_PER_SEC / rtc->irq_freq;
697 count = hrtimer_forward_now(timer, period);
698
699 rtc_handle_legacy_irq(rtc, count, RTC_PF);
700
701 return HRTIMER_RESTART;
702 }
703
704 /**
705 * rtc_update_irq - Triggered when a RTC interrupt occurs.
706 * @rtc: the rtc device
707 * @num: how many irqs are being reported (usually one)
708 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
709 * Context: any
710 */
rtc_update_irq(struct rtc_device * rtc,unsigned long num,unsigned long events)711 void rtc_update_irq(struct rtc_device *rtc,
712 unsigned long num, unsigned long events)
713 {
714 if (IS_ERR_OR_NULL(rtc))
715 return;
716
717 pm_stay_awake(rtc->dev.parent);
718 schedule_work(&rtc->irqwork);
719 }
720 EXPORT_SYMBOL_GPL(rtc_update_irq);
721
rtc_class_open(const char * name)722 struct rtc_device *rtc_class_open(const char *name)
723 {
724 struct device *dev;
725 struct rtc_device *rtc = NULL;
726
727 dev = class_find_device_by_name(&rtc_class, name);
728 if (dev)
729 rtc = to_rtc_device(dev);
730
731 if (rtc) {
732 if (!try_module_get(rtc->owner)) {
733 put_device(dev);
734 rtc = NULL;
735 }
736 }
737
738 return rtc;
739 }
740 EXPORT_SYMBOL_GPL(rtc_class_open);
741
rtc_class_close(struct rtc_device * rtc)742 void rtc_class_close(struct rtc_device *rtc)
743 {
744 module_put(rtc->owner);
745 put_device(&rtc->dev);
746 }
747 EXPORT_SYMBOL_GPL(rtc_class_close);
748
rtc_update_hrtimer(struct rtc_device * rtc,int enabled)749 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
750 {
751 /*
752 * We always cancel the timer here first, because otherwise
753 * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
754 * when we manage to start the timer before the callback
755 * returns HRTIMER_RESTART.
756 *
757 * We cannot use hrtimer_cancel() here as a running callback
758 * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
759 * would spin forever.
760 */
761 if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
762 return -1;
763
764 if (enabled) {
765 ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
766
767 hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
768 }
769 return 0;
770 }
771
772 /**
773 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
774 * @rtc: the rtc device
775 * @enabled: true to enable periodic IRQs
776 * Context: any
777 *
778 * Note that rtc_irq_set_freq() should previously have been used to
779 * specify the desired frequency of periodic IRQ.
780 */
rtc_irq_set_state(struct rtc_device * rtc,int enabled)781 int rtc_irq_set_state(struct rtc_device *rtc, int enabled)
782 {
783 int err = 0;
784
785 while (rtc_update_hrtimer(rtc, enabled) < 0)
786 cpu_relax();
787
788 rtc->pie_enabled = enabled;
789
790 trace_rtc_irq_set_state(enabled, err);
791 return err;
792 }
793
794 /**
795 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
796 * @rtc: the rtc device
797 * @freq: positive frequency
798 * Context: any
799 *
800 * Note that rtc_irq_set_state() is used to enable or disable the
801 * periodic IRQs.
802 */
rtc_irq_set_freq(struct rtc_device * rtc,int freq)803 int rtc_irq_set_freq(struct rtc_device *rtc, int freq)
804 {
805 int err = 0;
806
807 if (freq <= 0 || freq > RTC_MAX_FREQ)
808 return -EINVAL;
809
810 rtc->irq_freq = freq;
811 while (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0)
812 cpu_relax();
813
814 trace_rtc_irq_set_freq(freq, err);
815 return err;
816 }
817
818 /**
819 * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
820 * @rtc: rtc device
821 * @timer: timer being added.
822 *
823 * Enqueues a timer onto the rtc devices timerqueue and sets
824 * the next alarm event appropriately.
825 *
826 * Sets the enabled bit on the added timer.
827 *
828 * Must hold ops_lock for proper serialization of timerqueue
829 */
rtc_timer_enqueue(struct rtc_device * rtc,struct rtc_timer * timer)830 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
831 {
832 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
833 struct rtc_time tm;
834 ktime_t now;
835 int err;
836
837 err = __rtc_read_time(rtc, &tm);
838 if (err)
839 return err;
840
841 timer->enabled = 1;
842 now = rtc_tm_to_ktime(tm);
843
844 /* Skip over expired timers */
845 while (next) {
846 if (next->expires >= now)
847 break;
848 next = timerqueue_iterate_next(next);
849 }
850
851 timerqueue_add(&rtc->timerqueue, &timer->node);
852 trace_rtc_timer_enqueue(timer);
853 if (!next || ktime_before(timer->node.expires, next->expires)) {
854 struct rtc_wkalrm alarm;
855
856 alarm.time = rtc_ktime_to_tm(timer->node.expires);
857 alarm.enabled = 1;
858 err = __rtc_set_alarm(rtc, &alarm);
859 if (err == -ETIME) {
860 pm_stay_awake(rtc->dev.parent);
861 schedule_work(&rtc->irqwork);
862 } else if (err) {
863 timerqueue_del(&rtc->timerqueue, &timer->node);
864 trace_rtc_timer_dequeue(timer);
865 timer->enabled = 0;
866 return err;
867 }
868 }
869 return 0;
870 }
871
rtc_alarm_disable(struct rtc_device * rtc)872 static void rtc_alarm_disable(struct rtc_device *rtc)
873 {
874 if (!rtc->ops || !test_bit(RTC_FEATURE_ALARM, rtc->features) || !rtc->ops->alarm_irq_enable)
875 return;
876
877 rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
878 trace_rtc_alarm_irq_enable(0, 0);
879 }
880
881 /**
882 * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
883 * @rtc: rtc device
884 * @timer: timer being removed.
885 *
886 * Removes a timer onto the rtc devices timerqueue and sets
887 * the next alarm event appropriately.
888 *
889 * Clears the enabled bit on the removed timer.
890 *
891 * Must hold ops_lock for proper serialization of timerqueue
892 */
rtc_timer_remove(struct rtc_device * rtc,struct rtc_timer * timer)893 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
894 {
895 struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
896
897 timerqueue_del(&rtc->timerqueue, &timer->node);
898 trace_rtc_timer_dequeue(timer);
899 timer->enabled = 0;
900 if (next == &timer->node) {
901 struct rtc_wkalrm alarm;
902 int err;
903
904 next = timerqueue_getnext(&rtc->timerqueue);
905 if (!next) {
906 rtc_alarm_disable(rtc);
907 return;
908 }
909 alarm.time = rtc_ktime_to_tm(next->expires);
910 alarm.enabled = 1;
911 err = __rtc_set_alarm(rtc, &alarm);
912 if (err == -ETIME) {
913 pm_stay_awake(rtc->dev.parent);
914 schedule_work(&rtc->irqwork);
915 }
916 }
917 }
918
919 /**
920 * rtc_timer_do_work - Expires rtc timers
921 * @work: work item
922 *
923 * Expires rtc timers. Reprograms next alarm event if needed.
924 * Called via worktask.
925 *
926 * Serializes access to timerqueue via ops_lock mutex
927 */
rtc_timer_do_work(struct work_struct * work)928 void rtc_timer_do_work(struct work_struct *work)
929 {
930 struct rtc_timer *timer;
931 struct timerqueue_node *next;
932 ktime_t now;
933 struct rtc_time tm;
934 int err;
935
936 struct rtc_device *rtc =
937 container_of(work, struct rtc_device, irqwork);
938
939 mutex_lock(&rtc->ops_lock);
940 again:
941 err = __rtc_read_time(rtc, &tm);
942 if (err) {
943 mutex_unlock(&rtc->ops_lock);
944 return;
945 }
946 now = rtc_tm_to_ktime(tm);
947 while ((next = timerqueue_getnext(&rtc->timerqueue))) {
948 if (next->expires > now)
949 break;
950
951 /* expire timer */
952 timer = container_of(next, struct rtc_timer, node);
953 timerqueue_del(&rtc->timerqueue, &timer->node);
954 trace_rtc_timer_dequeue(timer);
955 timer->enabled = 0;
956 if (timer->func)
957 timer->func(timer->rtc);
958
959 trace_rtc_timer_fired(timer);
960 /* Re-add/fwd periodic timers */
961 if (ktime_to_ns(timer->period)) {
962 timer->node.expires = ktime_add(timer->node.expires,
963 timer->period);
964 timer->enabled = 1;
965 timerqueue_add(&rtc->timerqueue, &timer->node);
966 trace_rtc_timer_enqueue(timer);
967 }
968 }
969
970 /* Set next alarm */
971 if (next) {
972 struct rtc_wkalrm alarm;
973 int err;
974 int retry = 3;
975
976 alarm.time = rtc_ktime_to_tm(next->expires);
977 alarm.enabled = 1;
978 reprogram:
979 err = __rtc_set_alarm(rtc, &alarm);
980 if (err == -ETIME) {
981 goto again;
982 } else if (err) {
983 if (retry-- > 0)
984 goto reprogram;
985
986 timer = container_of(next, struct rtc_timer, node);
987 timerqueue_del(&rtc->timerqueue, &timer->node);
988 trace_rtc_timer_dequeue(timer);
989 timer->enabled = 0;
990 dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
991 goto again;
992 }
993 } else {
994 rtc_alarm_disable(rtc);
995 }
996
997 pm_relax(rtc->dev.parent);
998 mutex_unlock(&rtc->ops_lock);
999 }
1000
1001 /* rtc_timer_init - Initializes an rtc_timer
1002 * @timer: timer to be intiialized
1003 * @f: function pointer to be called when timer fires
1004 * @rtc: pointer to the rtc_device
1005 *
1006 * Kernel interface to initializing an rtc_timer.
1007 */
rtc_timer_init(struct rtc_timer * timer,void (* f)(struct rtc_device * r),struct rtc_device * rtc)1008 void rtc_timer_init(struct rtc_timer *timer, void (*f)(struct rtc_device *r),
1009 struct rtc_device *rtc)
1010 {
1011 timerqueue_init(&timer->node);
1012 timer->enabled = 0;
1013 timer->func = f;
1014 timer->rtc = rtc;
1015 }
1016
1017 /* rtc_timer_start - Sets an rtc_timer to fire in the future
1018 * @ rtc: rtc device to be used
1019 * @ timer: timer being set
1020 * @ expires: time at which to expire the timer
1021 * @ period: period that the timer will recur
1022 *
1023 * Kernel interface to set an rtc_timer
1024 */
rtc_timer_start(struct rtc_device * rtc,struct rtc_timer * timer,ktime_t expires,ktime_t period)1025 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
1026 ktime_t expires, ktime_t period)
1027 {
1028 int ret = 0;
1029
1030 mutex_lock(&rtc->ops_lock);
1031 if (timer->enabled)
1032 rtc_timer_remove(rtc, timer);
1033
1034 timer->node.expires = expires;
1035 timer->period = period;
1036
1037 ret = rtc_timer_enqueue(rtc, timer);
1038
1039 mutex_unlock(&rtc->ops_lock);
1040 return ret;
1041 }
1042
1043 /* rtc_timer_cancel - Stops an rtc_timer
1044 * @ rtc: rtc device to be used
1045 * @ timer: timer being set
1046 *
1047 * Kernel interface to cancel an rtc_timer
1048 */
rtc_timer_cancel(struct rtc_device * rtc,struct rtc_timer * timer)1049 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1050 {
1051 mutex_lock(&rtc->ops_lock);
1052 if (timer->enabled)
1053 rtc_timer_remove(rtc, timer);
1054 mutex_unlock(&rtc->ops_lock);
1055 }
1056
1057 /**
1058 * rtc_read_offset - Read the amount of rtc offset in parts per billion
1059 * @rtc: rtc device to be used
1060 * @offset: the offset in parts per billion
1061 *
1062 * see below for details.
1063 *
1064 * Kernel interface to read rtc clock offset
1065 * Returns 0 on success, or a negative number on error.
1066 * If read_offset() is not implemented for the rtc, return -EINVAL
1067 */
rtc_read_offset(struct rtc_device * rtc,long * offset)1068 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1069 {
1070 int ret;
1071
1072 if (!rtc->ops)
1073 return -ENODEV;
1074
1075 if (!rtc->ops->read_offset)
1076 return -EINVAL;
1077
1078 mutex_lock(&rtc->ops_lock);
1079 ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1080 mutex_unlock(&rtc->ops_lock);
1081
1082 trace_rtc_read_offset(*offset, ret);
1083 return ret;
1084 }
1085
1086 /**
1087 * rtc_set_offset - Adjusts the duration of the average second
1088 * @rtc: rtc device to be used
1089 * @offset: the offset in parts per billion
1090 *
1091 * Some rtc's allow an adjustment to the average duration of a second
1092 * to compensate for differences in the actual clock rate due to temperature,
1093 * the crystal, capacitor, etc.
1094 *
1095 * The adjustment applied is as follows:
1096 * t = t0 * (1 + offset * 1e-9)
1097 * where t0 is the measured length of 1 RTC second with offset = 0
1098 *
1099 * Kernel interface to adjust an rtc clock offset.
1100 * Return 0 on success, or a negative number on error.
1101 * If the rtc offset is not setable (or not implemented), return -EINVAL
1102 */
rtc_set_offset(struct rtc_device * rtc,long offset)1103 int rtc_set_offset(struct rtc_device *rtc, long offset)
1104 {
1105 int ret;
1106
1107 if (!rtc->ops)
1108 return -ENODEV;
1109
1110 if (!rtc->ops->set_offset)
1111 return -EINVAL;
1112
1113 mutex_lock(&rtc->ops_lock);
1114 ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1115 mutex_unlock(&rtc->ops_lock);
1116
1117 trace_rtc_set_offset(offset, ret);
1118 return ret;
1119 }
1120