xref: /openbmc/linux/drivers/rtc/interface.c (revision 42bc47b3)
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 
23 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer);
24 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer);
25 
26 static 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 
49 static 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 
70 static 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 
87 static 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 
112 int 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 }
126 EXPORT_SYMBOL_GPL(rtc_read_time);
127 
128 int 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 }
168 EXPORT_SYMBOL_GPL(rtc_set_time);
169 
170 static 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 
203 int __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 
368 done:
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 
379 int 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 }
400 EXPORT_SYMBOL_GPL(rtc_read_alarm);
401 
402 static 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 
440 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
441 {
442 	int err;
443 
444 	if (!rtc->ops)
445 		return -ENODEV;
446 	else if (!rtc->ops->set_alarm)
447 		return -EINVAL;
448 
449 	err = rtc_valid_tm(&alarm->time);
450 	if (err != 0)
451 		return err;
452 
453 	err = rtc_valid_range(rtc, &alarm->time);
454 	if (err)
455 		return err;
456 
457 	err = mutex_lock_interruptible(&rtc->ops_lock);
458 	if (err)
459 		return err;
460 	if (rtc->aie_timer.enabled)
461 		rtc_timer_remove(rtc, &rtc->aie_timer);
462 
463 	rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
464 	rtc->aie_timer.period = 0;
465 	if (alarm->enabled)
466 		err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
467 
468 	mutex_unlock(&rtc->ops_lock);
469 
470 	rtc_add_offset(rtc, &alarm->time);
471 	return err;
472 }
473 EXPORT_SYMBOL_GPL(rtc_set_alarm);
474 
475 /* Called once per device from rtc_device_register */
476 int rtc_initialize_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
477 {
478 	int err;
479 	struct rtc_time now;
480 
481 	err = rtc_valid_tm(&alarm->time);
482 	if (err != 0)
483 		return err;
484 
485 	err = rtc_read_time(rtc, &now);
486 	if (err)
487 		return err;
488 
489 	err = mutex_lock_interruptible(&rtc->ops_lock);
490 	if (err)
491 		return err;
492 
493 	rtc->aie_timer.node.expires = rtc_tm_to_ktime(alarm->time);
494 	rtc->aie_timer.period = 0;
495 
496 	/* Alarm has to be enabled & in the future for us to enqueue it */
497 	if (alarm->enabled && (rtc_tm_to_ktime(now) <
498 			 rtc->aie_timer.node.expires)) {
499 
500 		rtc->aie_timer.enabled = 1;
501 		timerqueue_add(&rtc->timerqueue, &rtc->aie_timer.node);
502 		trace_rtc_timer_enqueue(&rtc->aie_timer);
503 	}
504 	mutex_unlock(&rtc->ops_lock);
505 	return err;
506 }
507 EXPORT_SYMBOL_GPL(rtc_initialize_alarm);
508 
509 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
510 {
511 	int err = mutex_lock_interruptible(&rtc->ops_lock);
512 	if (err)
513 		return err;
514 
515 	if (rtc->aie_timer.enabled != enabled) {
516 		if (enabled)
517 			err = rtc_timer_enqueue(rtc, &rtc->aie_timer);
518 		else
519 			rtc_timer_remove(rtc, &rtc->aie_timer);
520 	}
521 
522 	if (err)
523 		/* nothing */;
524 	else if (!rtc->ops)
525 		err = -ENODEV;
526 	else if (!rtc->ops->alarm_irq_enable)
527 		err = -EINVAL;
528 	else
529 		err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
530 
531 	mutex_unlock(&rtc->ops_lock);
532 
533 	trace_rtc_alarm_irq_enable(enabled, err);
534 	return err;
535 }
536 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
537 
538 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
539 {
540 	int err = mutex_lock_interruptible(&rtc->ops_lock);
541 	if (err)
542 		return err;
543 
544 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
545 	if (enabled == 0 && rtc->uie_irq_active) {
546 		mutex_unlock(&rtc->ops_lock);
547 		return rtc_dev_update_irq_enable_emul(rtc, 0);
548 	}
549 #endif
550 	/* make sure we're changing state */
551 	if (rtc->uie_rtctimer.enabled == enabled)
552 		goto out;
553 
554 	if (rtc->uie_unsupported) {
555 		err = -EINVAL;
556 		goto out;
557 	}
558 
559 	if (enabled) {
560 		struct rtc_time tm;
561 		ktime_t now, onesec;
562 
563 		__rtc_read_time(rtc, &tm);
564 		onesec = ktime_set(1, 0);
565 		now = rtc_tm_to_ktime(tm);
566 		rtc->uie_rtctimer.node.expires = ktime_add(now, onesec);
567 		rtc->uie_rtctimer.period = ktime_set(1, 0);
568 		err = rtc_timer_enqueue(rtc, &rtc->uie_rtctimer);
569 	} else
570 		rtc_timer_remove(rtc, &rtc->uie_rtctimer);
571 
572 out:
573 	mutex_unlock(&rtc->ops_lock);
574 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
575 	/*
576 	 * Enable emulation if the driver did not provide
577 	 * the update_irq_enable function pointer or if returned
578 	 * -EINVAL to signal that it has been configured without
579 	 * interrupts or that are not available at the moment.
580 	 */
581 	if (err == -EINVAL)
582 		err = rtc_dev_update_irq_enable_emul(rtc, enabled);
583 #endif
584 	return err;
585 
586 }
587 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
588 
589 
590 /**
591  * rtc_handle_legacy_irq - AIE, UIE and PIE event hook
592  * @rtc: pointer to the rtc device
593  *
594  * This function is called when an AIE, UIE or PIE mode interrupt
595  * has occurred (or been emulated).
596  *
597  * Triggers the registered irq_task function callback.
598  */
599 void rtc_handle_legacy_irq(struct rtc_device *rtc, int num, int mode)
600 {
601 	unsigned long flags;
602 
603 	/* mark one irq of the appropriate mode */
604 	spin_lock_irqsave(&rtc->irq_lock, flags);
605 	rtc->irq_data = (rtc->irq_data + (num << 8)) | (RTC_IRQF|mode);
606 	spin_unlock_irqrestore(&rtc->irq_lock, flags);
607 
608 	/* call the task func */
609 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
610 	if (rtc->irq_task)
611 		rtc->irq_task->func(rtc->irq_task->private_data);
612 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
613 
614 	wake_up_interruptible(&rtc->irq_queue);
615 	kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
616 }
617 
618 
619 /**
620  * rtc_aie_update_irq - AIE mode rtctimer hook
621  * @private: pointer to the rtc_device
622  *
623  * This functions is called when the aie_timer expires.
624  */
625 void rtc_aie_update_irq(void *private)
626 {
627 	struct rtc_device *rtc = (struct rtc_device *)private;
628 	rtc_handle_legacy_irq(rtc, 1, RTC_AF);
629 }
630 
631 
632 /**
633  * rtc_uie_update_irq - UIE mode rtctimer hook
634  * @private: pointer to the rtc_device
635  *
636  * This functions is called when the uie_timer expires.
637  */
638 void rtc_uie_update_irq(void *private)
639 {
640 	struct rtc_device *rtc = (struct rtc_device *)private;
641 	rtc_handle_legacy_irq(rtc, 1,  RTC_UF);
642 }
643 
644 
645 /**
646  * rtc_pie_update_irq - PIE mode hrtimer hook
647  * @timer: pointer to the pie mode hrtimer
648  *
649  * This function is used to emulate PIE mode interrupts
650  * using an hrtimer. This function is called when the periodic
651  * hrtimer expires.
652  */
653 enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
654 {
655 	struct rtc_device *rtc;
656 	ktime_t period;
657 	int count;
658 	rtc = container_of(timer, struct rtc_device, pie_timer);
659 
660 	period = NSEC_PER_SEC / rtc->irq_freq;
661 	count = hrtimer_forward_now(timer, period);
662 
663 	rtc_handle_legacy_irq(rtc, count, RTC_PF);
664 
665 	return HRTIMER_RESTART;
666 }
667 
668 /**
669  * rtc_update_irq - Triggered when a RTC interrupt occurs.
670  * @rtc: the rtc device
671  * @num: how many irqs are being reported (usually one)
672  * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
673  * Context: any
674  */
675 void rtc_update_irq(struct rtc_device *rtc,
676 		unsigned long num, unsigned long events)
677 {
678 	if (IS_ERR_OR_NULL(rtc))
679 		return;
680 
681 	pm_stay_awake(rtc->dev.parent);
682 	schedule_work(&rtc->irqwork);
683 }
684 EXPORT_SYMBOL_GPL(rtc_update_irq);
685 
686 static int __rtc_match(struct device *dev, const void *data)
687 {
688 	const char *name = data;
689 
690 	if (strcmp(dev_name(dev), name) == 0)
691 		return 1;
692 	return 0;
693 }
694 
695 struct 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(rtc_class, NULL, name, __rtc_match);
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 }
713 EXPORT_SYMBOL_GPL(rtc_class_open);
714 
715 void rtc_class_close(struct rtc_device *rtc)
716 {
717 	module_put(rtc->owner);
718 	put_device(&rtc->dev);
719 }
720 EXPORT_SYMBOL_GPL(rtc_class_close);
721 
722 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
723 {
724 	int retval = -EBUSY;
725 
726 	if (task == NULL || task->func == NULL)
727 		return -EINVAL;
728 
729 	/* Cannot register while the char dev is in use */
730 	if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
731 		return -EBUSY;
732 
733 	spin_lock_irq(&rtc->irq_task_lock);
734 	if (rtc->irq_task == NULL) {
735 		rtc->irq_task = task;
736 		retval = 0;
737 	}
738 	spin_unlock_irq(&rtc->irq_task_lock);
739 
740 	clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
741 
742 	return retval;
743 }
744 EXPORT_SYMBOL_GPL(rtc_irq_register);
745 
746 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
747 {
748 	spin_lock_irq(&rtc->irq_task_lock);
749 	if (rtc->irq_task == task)
750 		rtc->irq_task = NULL;
751 	spin_unlock_irq(&rtc->irq_task_lock);
752 }
753 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
754 
755 static int rtc_update_hrtimer(struct rtc_device *rtc, int enabled)
756 {
757 	/*
758 	 * We always cancel the timer here first, because otherwise
759 	 * we could run into BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
760 	 * when we manage to start the timer before the callback
761 	 * returns HRTIMER_RESTART.
762 	 *
763 	 * We cannot use hrtimer_cancel() here as a running callback
764 	 * could be blocked on rtc->irq_task_lock and hrtimer_cancel()
765 	 * would spin forever.
766 	 */
767 	if (hrtimer_try_to_cancel(&rtc->pie_timer) < 0)
768 		return -1;
769 
770 	if (enabled) {
771 		ktime_t period = NSEC_PER_SEC / rtc->irq_freq;
772 
773 		hrtimer_start(&rtc->pie_timer, period, HRTIMER_MODE_REL);
774 	}
775 	return 0;
776 }
777 
778 /**
779  * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
780  * @rtc: the rtc device
781  * @task: currently registered with rtc_irq_register()
782  * @enabled: true to enable periodic IRQs
783  * Context: any
784  *
785  * Note that rtc_irq_set_freq() should previously have been used to
786  * specify the desired frequency of periodic IRQ task->func() callbacks.
787  */
788 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
789 {
790 	int err = 0;
791 	unsigned long flags;
792 
793 retry:
794 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
795 	if (rtc->irq_task != NULL && task == NULL)
796 		err = -EBUSY;
797 	else if (rtc->irq_task != task)
798 		err = -EACCES;
799 	else {
800 		if (rtc_update_hrtimer(rtc, enabled) < 0) {
801 			spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
802 			cpu_relax();
803 			goto retry;
804 		}
805 		rtc->pie_enabled = enabled;
806 	}
807 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
808 
809 	trace_rtc_irq_set_state(enabled, err);
810 	return err;
811 }
812 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
813 
814 /**
815  * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
816  * @rtc: the rtc device
817  * @task: currently registered with rtc_irq_register()
818  * @freq: positive frequency with which task->func() will be called
819  * Context: any
820  *
821  * Note that rtc_irq_set_state() is used to enable or disable the
822  * periodic IRQs.
823  */
824 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
825 {
826 	int err = 0;
827 	unsigned long flags;
828 
829 	if (freq <= 0 || freq > RTC_MAX_FREQ)
830 		return -EINVAL;
831 retry:
832 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
833 	if (rtc->irq_task != NULL && task == NULL)
834 		err = -EBUSY;
835 	else if (rtc->irq_task != task)
836 		err = -EACCES;
837 	else {
838 		rtc->irq_freq = freq;
839 		if (rtc->pie_enabled && rtc_update_hrtimer(rtc, 1) < 0) {
840 			spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
841 			cpu_relax();
842 			goto retry;
843 		}
844 	}
845 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
846 
847 	trace_rtc_irq_set_freq(freq, err);
848 	return err;
849 }
850 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
851 
852 /**
853  * rtc_timer_enqueue - Adds a rtc_timer to the rtc_device timerqueue
854  * @rtc rtc device
855  * @timer timer being added.
856  *
857  * Enqueues a timer onto the rtc devices timerqueue and sets
858  * the next alarm event appropriately.
859  *
860  * Sets the enabled bit on the added timer.
861  *
862  * Must hold ops_lock for proper serialization of timerqueue
863  */
864 static int rtc_timer_enqueue(struct rtc_device *rtc, struct rtc_timer *timer)
865 {
866 	struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
867 	struct rtc_time tm;
868 	ktime_t now;
869 
870 	timer->enabled = 1;
871 	__rtc_read_time(rtc, &tm);
872 	now = rtc_tm_to_ktime(tm);
873 
874 	/* Skip over expired timers */
875 	while (next) {
876 		if (next->expires >= now)
877 			break;
878 		next = timerqueue_iterate_next(next);
879 	}
880 
881 	timerqueue_add(&rtc->timerqueue, &timer->node);
882 	trace_rtc_timer_enqueue(timer);
883 	if (!next || ktime_before(timer->node.expires, next->expires)) {
884 		struct rtc_wkalrm alarm;
885 		int err;
886 		alarm.time = rtc_ktime_to_tm(timer->node.expires);
887 		alarm.enabled = 1;
888 		err = __rtc_set_alarm(rtc, &alarm);
889 		if (err == -ETIME) {
890 			pm_stay_awake(rtc->dev.parent);
891 			schedule_work(&rtc->irqwork);
892 		} else if (err) {
893 			timerqueue_del(&rtc->timerqueue, &timer->node);
894 			trace_rtc_timer_dequeue(timer);
895 			timer->enabled = 0;
896 			return err;
897 		}
898 	}
899 	return 0;
900 }
901 
902 static void rtc_alarm_disable(struct rtc_device *rtc)
903 {
904 	if (!rtc->ops || !rtc->ops->alarm_irq_enable)
905 		return;
906 
907 	rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
908 	trace_rtc_alarm_irq_enable(0, 0);
909 }
910 
911 /**
912  * rtc_timer_remove - Removes a rtc_timer from the rtc_device timerqueue
913  * @rtc rtc device
914  * @timer timer being removed.
915  *
916  * Removes a timer onto the rtc devices timerqueue and sets
917  * the next alarm event appropriately.
918  *
919  * Clears the enabled bit on the removed timer.
920  *
921  * Must hold ops_lock for proper serialization of timerqueue
922  */
923 static void rtc_timer_remove(struct rtc_device *rtc, struct rtc_timer *timer)
924 {
925 	struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
926 	timerqueue_del(&rtc->timerqueue, &timer->node);
927 	trace_rtc_timer_dequeue(timer);
928 	timer->enabled = 0;
929 	if (next == &timer->node) {
930 		struct rtc_wkalrm alarm;
931 		int err;
932 		next = timerqueue_getnext(&rtc->timerqueue);
933 		if (!next) {
934 			rtc_alarm_disable(rtc);
935 			return;
936 		}
937 		alarm.time = rtc_ktime_to_tm(next->expires);
938 		alarm.enabled = 1;
939 		err = __rtc_set_alarm(rtc, &alarm);
940 		if (err == -ETIME) {
941 			pm_stay_awake(rtc->dev.parent);
942 			schedule_work(&rtc->irqwork);
943 		}
944 	}
945 }
946 
947 /**
948  * rtc_timer_do_work - Expires rtc timers
949  * @rtc rtc device
950  * @timer timer being removed.
951  *
952  * Expires rtc timers. Reprograms next alarm event if needed.
953  * Called via worktask.
954  *
955  * Serializes access to timerqueue via ops_lock mutex
956  */
957 void rtc_timer_do_work(struct work_struct *work)
958 {
959 	struct rtc_timer *timer;
960 	struct timerqueue_node *next;
961 	ktime_t now;
962 	struct rtc_time tm;
963 
964 	struct rtc_device *rtc =
965 		container_of(work, struct rtc_device, irqwork);
966 
967 	mutex_lock(&rtc->ops_lock);
968 again:
969 	__rtc_read_time(rtc, &tm);
970 	now = rtc_tm_to_ktime(tm);
971 	while ((next = timerqueue_getnext(&rtc->timerqueue))) {
972 		if (next->expires > now)
973 			break;
974 
975 		/* expire timer */
976 		timer = container_of(next, struct rtc_timer, node);
977 		timerqueue_del(&rtc->timerqueue, &timer->node);
978 		trace_rtc_timer_dequeue(timer);
979 		timer->enabled = 0;
980 		if (timer->task.func)
981 			timer->task.func(timer->task.private_data);
982 
983 		trace_rtc_timer_fired(timer);
984 		/* Re-add/fwd periodic timers */
985 		if (ktime_to_ns(timer->period)) {
986 			timer->node.expires = ktime_add(timer->node.expires,
987 							timer->period);
988 			timer->enabled = 1;
989 			timerqueue_add(&rtc->timerqueue, &timer->node);
990 			trace_rtc_timer_enqueue(timer);
991 		}
992 	}
993 
994 	/* Set next alarm */
995 	if (next) {
996 		struct rtc_wkalrm alarm;
997 		int err;
998 		int retry = 3;
999 
1000 		alarm.time = rtc_ktime_to_tm(next->expires);
1001 		alarm.enabled = 1;
1002 reprogram:
1003 		err = __rtc_set_alarm(rtc, &alarm);
1004 		if (err == -ETIME)
1005 			goto again;
1006 		else if (err) {
1007 			if (retry-- > 0)
1008 				goto reprogram;
1009 
1010 			timer = container_of(next, struct rtc_timer, node);
1011 			timerqueue_del(&rtc->timerqueue, &timer->node);
1012 			trace_rtc_timer_dequeue(timer);
1013 			timer->enabled = 0;
1014 			dev_err(&rtc->dev, "__rtc_set_alarm: err=%d\n", err);
1015 			goto again;
1016 		}
1017 	} else
1018 		rtc_alarm_disable(rtc);
1019 
1020 	pm_relax(rtc->dev.parent);
1021 	mutex_unlock(&rtc->ops_lock);
1022 }
1023 
1024 
1025 /* rtc_timer_init - Initializes an rtc_timer
1026  * @timer: timer to be intiialized
1027  * @f: function pointer to be called when timer fires
1028  * @data: private data passed to function pointer
1029  *
1030  * Kernel interface to initializing an rtc_timer.
1031  */
1032 void rtc_timer_init(struct rtc_timer *timer, void (*f)(void *p), void *data)
1033 {
1034 	timerqueue_init(&timer->node);
1035 	timer->enabled = 0;
1036 	timer->task.func = f;
1037 	timer->task.private_data = data;
1038 }
1039 
1040 /* rtc_timer_start - Sets an rtc_timer to fire in the future
1041  * @ rtc: rtc device to be used
1042  * @ timer: timer being set
1043  * @ expires: time at which to expire the timer
1044  * @ period: period that the timer will recur
1045  *
1046  * Kernel interface to set an rtc_timer
1047  */
1048 int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
1049 			ktime_t expires, ktime_t period)
1050 {
1051 	int ret = 0;
1052 	mutex_lock(&rtc->ops_lock);
1053 	if (timer->enabled)
1054 		rtc_timer_remove(rtc, timer);
1055 
1056 	timer->node.expires = expires;
1057 	timer->period = period;
1058 
1059 	ret = rtc_timer_enqueue(rtc, timer);
1060 
1061 	mutex_unlock(&rtc->ops_lock);
1062 	return ret;
1063 }
1064 
1065 /* rtc_timer_cancel - Stops an rtc_timer
1066  * @ rtc: rtc device to be used
1067  * @ timer: timer being set
1068  *
1069  * Kernel interface to cancel an rtc_timer
1070  */
1071 void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer)
1072 {
1073 	mutex_lock(&rtc->ops_lock);
1074 	if (timer->enabled)
1075 		rtc_timer_remove(rtc, timer);
1076 	mutex_unlock(&rtc->ops_lock);
1077 }
1078 
1079 /**
1080  * rtc_read_offset - Read the amount of rtc offset in parts per billion
1081  * @ rtc: rtc device to be used
1082  * @ offset: the offset in parts per billion
1083  *
1084  * see below for details.
1085  *
1086  * Kernel interface to read rtc clock offset
1087  * Returns 0 on success, or a negative number on error.
1088  * If read_offset() is not implemented for the rtc, return -EINVAL
1089  */
1090 int rtc_read_offset(struct rtc_device *rtc, long *offset)
1091 {
1092 	int ret;
1093 
1094 	if (!rtc->ops)
1095 		return -ENODEV;
1096 
1097 	if (!rtc->ops->read_offset)
1098 		return -EINVAL;
1099 
1100 	mutex_lock(&rtc->ops_lock);
1101 	ret = rtc->ops->read_offset(rtc->dev.parent, offset);
1102 	mutex_unlock(&rtc->ops_lock);
1103 
1104 	trace_rtc_read_offset(*offset, ret);
1105 	return ret;
1106 }
1107 
1108 /**
1109  * rtc_set_offset - Adjusts the duration of the average second
1110  * @ rtc: rtc device to be used
1111  * @ offset: the offset in parts per billion
1112  *
1113  * Some rtc's allow an adjustment to the average duration of a second
1114  * to compensate for differences in the actual clock rate due to temperature,
1115  * the crystal, capacitor, etc.
1116  *
1117  * The adjustment applied is as follows:
1118  *   t = t0 * (1 + offset * 1e-9)
1119  * where t0 is the measured length of 1 RTC second with offset = 0
1120  *
1121  * Kernel interface to adjust an rtc clock offset.
1122  * Return 0 on success, or a negative number on error.
1123  * If the rtc offset is not setable (or not implemented), return -EINVAL
1124  */
1125 int rtc_set_offset(struct rtc_device *rtc, long offset)
1126 {
1127 	int ret;
1128 
1129 	if (!rtc->ops)
1130 		return -ENODEV;
1131 
1132 	if (!rtc->ops->set_offset)
1133 		return -EINVAL;
1134 
1135 	mutex_lock(&rtc->ops_lock);
1136 	ret = rtc->ops->set_offset(rtc->dev.parent, offset);
1137 	mutex_unlock(&rtc->ops_lock);
1138 
1139 	trace_rtc_set_offset(offset, ret);
1140 	return ret;
1141 }
1142