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/log2.h>
16
17 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
18 {
19 int err;
20
21 err = mutex_lock_interruptible(&rtc->ops_lock);
22 if (err)
23 return err;
24
25 if (!rtc->ops)
26 err = -ENODEV;
27 else if (!rtc->ops->read_time)
28 err = -EINVAL;
29 else {
30 memset(tm, 0, sizeof(struct rtc_time));
31 err = rtc->ops->read_time(rtc->dev.parent, tm);
32 }
33
34 mutex_unlock(&rtc->ops_lock);
35 return err;
36 }
37 EXPORT_SYMBOL_GPL(rtc_read_time);
38
39 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm)
40 {
41 int err;
42
43 err = rtc_valid_tm(tm);
44 if (err != 0)
45 return err;
46
47 err = mutex_lock_interruptible(&rtc->ops_lock);
48 if (err)
49 return err;
50
51 if (!rtc->ops)
52 err = -ENODEV;
53 else if (rtc->ops->set_time)
54 err = rtc->ops->set_time(rtc->dev.parent, tm);
55 else if (rtc->ops->set_mmss) {
56 unsigned long secs;
57 err = rtc_tm_to_time(tm, &secs);
58 if (err == 0)
59 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
60 } else
61 err = -EINVAL;
62
63 mutex_unlock(&rtc->ops_lock);
64 return err;
65 }
66 EXPORT_SYMBOL_GPL(rtc_set_time);
67
68 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
69 {
70 int err;
71
72 err = mutex_lock_interruptible(&rtc->ops_lock);
73 if (err)
74 return err;
75
76 if (!rtc->ops)
77 err = -ENODEV;
78 else if (rtc->ops->set_mmss)
79 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
80 else if (rtc->ops->read_time && rtc->ops->set_time) {
81 struct rtc_time new, old;
82
83 err = rtc->ops->read_time(rtc->dev.parent, &old);
84 if (err == 0) {
85 rtc_time_to_tm(secs, &new);
86
87 /*
88 * avoid writing when we're going to change the day of
89 * the month. We will retry in the next minute. This
90 * basically means that if the RTC must not drift
91 * by more than 1 minute in 11 minutes.
92 */
93 if (!((old.tm_hour == 23 && old.tm_min == 59) ||
94 (new.tm_hour == 23 && new.tm_min == 59)))
95 err = rtc->ops->set_time(rtc->dev.parent,
96 &new);
97 }
98 }
99 else
100 err = -EINVAL;
101
102 mutex_unlock(&rtc->ops_lock);
103
104 return err;
105 }
106 EXPORT_SYMBOL_GPL(rtc_set_mmss);
107
108 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
109 {
110 int err;
111
112 err = mutex_lock_interruptible(&rtc->ops_lock);
113 if (err)
114 return err;
115
116 if (rtc->ops == NULL)
117 err = -ENODEV;
118 else if (!rtc->ops->read_alarm)
119 err = -EINVAL;
120 else {
121 memset(alarm, 0, sizeof(struct rtc_wkalrm));
122 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
123 }
124
125 mutex_unlock(&rtc->ops_lock);
126 return err;
127 }
128
129 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
130 {
131 int err;
132 struct rtc_time before, now;
133 int first_time = 1;
134 unsigned long t_now, t_alm;
135 enum { none, day, month, year } missing = none;
136 unsigned days;
137
138 /* The lower level RTC driver may return -1 in some fields,
139 * creating invalid alarm->time values, for reasons like:
140 *
141 * - The hardware may not be capable of filling them in;
142 * many alarms match only on time-of-day fields, not
143 * day/month/year calendar data.
144 *
145 * - Some hardware uses illegal values as "wildcard" match
146 * values, which non-Linux firmware (like a BIOS) may try
147 * to set up as e.g. "alarm 15 minutes after each hour".
148 * Linux uses only oneshot alarms.
149 *
150 * When we see that here, we deal with it by using values from
151 * a current RTC timestamp for any missing (-1) values. The
152 * RTC driver prevents "periodic alarm" modes.
153 *
154 * But this can be racey, because some fields of the RTC timestamp
155 * may have wrapped in the interval since we read the RTC alarm,
156 * which would lead to us inserting inconsistent values in place
157 * of the -1 fields.
158 *
159 * Reading the alarm and timestamp in the reverse sequence
160 * would have the same race condition, and not solve the issue.
161 *
162 * So, we must first read the RTC timestamp,
163 * then read the RTC alarm value,
164 * and then read a second RTC timestamp.
165 *
166 * If any fields of the second timestamp have changed
167 * when compared with the first timestamp, then we know
168 * our timestamp may be inconsistent with that used by
169 * the low-level rtc_read_alarm_internal() function.
170 *
171 * So, when the two timestamps disagree, we just loop and do
172 * the process again to get a fully consistent set of values.
173 *
174 * This could all instead be done in the lower level driver,
175 * but since more than one lower level RTC implementation needs it,
176 * then it's probably best best to do it here instead of there..
177 */
178
179 /* Get the "before" timestamp */
180 err = rtc_read_time(rtc, &before);
181 if (err < 0)
182 return err;
183 do {
184 if (!first_time)
185 memcpy(&before, &now, sizeof(struct rtc_time));
186 first_time = 0;
187
188 /* get the RTC alarm values, which may be incomplete */
189 err = rtc_read_alarm_internal(rtc, alarm);
190 if (err)
191 return err;
192 if (!alarm->enabled)
193 return 0;
194
195 /* full-function RTCs won't have such missing fields */
196 if (rtc_valid_tm(&alarm->time) == 0)
197 return 0;
198
199 /* get the "after" timestamp, to detect wrapped fields */
200 err = rtc_read_time(rtc, &now);
201 if (err < 0)
202 return err;
203
204 /* note that tm_sec is a "don't care" value here: */
205 } while ( before.tm_min != now.tm_min
206 || before.tm_hour != now.tm_hour
207 || before.tm_mon != now.tm_mon
208 || before.tm_year != now.tm_year);
209
210 /* Fill in the missing alarm fields using the timestamp; we
211 * know there's at least one since alarm->time is invalid.
212 */
213 if (alarm->time.tm_sec == -1)
214 alarm->time.tm_sec = now.tm_sec;
215 if (alarm->time.tm_min == -1)
216 alarm->time.tm_min = now.tm_min;
217 if (alarm->time.tm_hour == -1)
218 alarm->time.tm_hour = now.tm_hour;
219
220 /* For simplicity, only support date rollover for now */
221 if (alarm->time.tm_mday == -1) {
222 alarm->time.tm_mday = now.tm_mday;
223 missing = day;
224 }
225 if (alarm->time.tm_mon == -1) {
226 alarm->time.tm_mon = now.tm_mon;
227 if (missing == none)
228 missing = month;
229 }
230 if (alarm->time.tm_year == -1) {
231 alarm->time.tm_year = now.tm_year;
232 if (missing == none)
233 missing = year;
234 }
235
236 /* with luck, no rollover is needed */
237 rtc_tm_to_time(&now, &t_now);
238 rtc_tm_to_time(&alarm->time, &t_alm);
239 if (t_now < t_alm)
240 goto done;
241
242 switch (missing) {
243
244 /* 24 hour rollover ... if it's now 10am Monday, an alarm that
245 * that will trigger at 5am will do so at 5am Tuesday, which
246 * could also be in the next month or year. This is a common
247 * case, especially for PCs.
248 */
249 case day:
250 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
251 t_alm += 24 * 60 * 60;
252 rtc_time_to_tm(t_alm, &alarm->time);
253 break;
254
255 /* Month rollover ... if it's the 31th, an alarm on the 3rd will
256 * be next month. An alarm matching on the 30th, 29th, or 28th
257 * may end up in the month after that! Many newer PCs support
258 * this type of alarm.
259 */
260 case month:
261 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
262 do {
263 if (alarm->time.tm_mon < 11)
264 alarm->time.tm_mon++;
265 else {
266 alarm->time.tm_mon = 0;
267 alarm->time.tm_year++;
268 }
269 days = rtc_month_days(alarm->time.tm_mon,
270 alarm->time.tm_year);
271 } while (days < alarm->time.tm_mday);
272 break;
273
274 /* Year rollover ... easy except for leap years! */
275 case year:
276 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
277 do {
278 alarm->time.tm_year++;
279 } while (rtc_valid_tm(&alarm->time) != 0);
280 break;
281
282 default:
283 dev_warn(&rtc->dev, "alarm rollover not handled\n");
284 }
285
286 done:
287 return 0;
288 }
289 EXPORT_SYMBOL_GPL(rtc_read_alarm);
290
291 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
292 {
293 int err;
294
295 err = rtc_valid_tm(&alarm->time);
296 if (err != 0)
297 return err;
298
299 err = mutex_lock_interruptible(&rtc->ops_lock);
300 if (err)
301 return err;
302
303 if (!rtc->ops)
304 err = -ENODEV;
305 else if (!rtc->ops->set_alarm)
306 err = -EINVAL;
307 else
308 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
309
310 mutex_unlock(&rtc->ops_lock);
311 return err;
312 }
313 EXPORT_SYMBOL_GPL(rtc_set_alarm);
314
315 int rtc_alarm_irq_enable(struct rtc_device *rtc, unsigned int enabled)
316 {
317 int err = mutex_lock_interruptible(&rtc->ops_lock);
318 if (err)
319 return err;
320
321 if (!rtc->ops)
322 err = -ENODEV;
323 else if (!rtc->ops->alarm_irq_enable)
324 err = -EINVAL;
325 else
326 err = rtc->ops->alarm_irq_enable(rtc->dev.parent, enabled);
327
328 mutex_unlock(&rtc->ops_lock);
329 return err;
330 }
331 EXPORT_SYMBOL_GPL(rtc_alarm_irq_enable);
332
333 int rtc_update_irq_enable(struct rtc_device *rtc, unsigned int enabled)
334 {
335 int err = mutex_lock_interruptible(&rtc->ops_lock);
336 if (err)
337 return err;
338
339 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
340 if (enabled == 0 && rtc->uie_irq_active) {
341 mutex_unlock(&rtc->ops_lock);
342 return rtc_dev_update_irq_enable_emul(rtc, enabled);
343 }
344 #endif
345
346 if (!rtc->ops)
347 err = -ENODEV;
348 else if (!rtc->ops->update_irq_enable)
349 err = -EINVAL;
350 else
351 err = rtc->ops->update_irq_enable(rtc->dev.parent, enabled);
352
353 mutex_unlock(&rtc->ops_lock);
354
355 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
356 /*
357 * Enable emulation if the driver did not provide
358 * the update_irq_enable function pointer or if returned
359 * -EINVAL to signal that it has been configured without
360 * interrupts or that are not available at the moment.
361 */
362 if (err == -EINVAL)
363 err = rtc_dev_update_irq_enable_emul(rtc, enabled);
364 #endif
365 return err;
366 }
367 EXPORT_SYMBOL_GPL(rtc_update_irq_enable);
368
369 /**
370 * rtc_update_irq - report RTC periodic, alarm, and/or update irqs
371 * @rtc: the rtc device
372 * @num: how many irqs are being reported (usually one)
373 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
374 * Context: any
375 */
376 void rtc_update_irq(struct rtc_device *rtc,
377 unsigned long num, unsigned long events)
378 {
379 unsigned long flags;
380
381 spin_lock_irqsave(&rtc->irq_lock, flags);
382 rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
383 spin_unlock_irqrestore(&rtc->irq_lock, flags);
384
385 spin_lock_irqsave(&rtc->irq_task_lock, flags);
386 if (rtc->irq_task)
387 rtc->irq_task->func(rtc->irq_task->private_data);
388 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
389
390 wake_up_interruptible(&rtc->irq_queue);
391 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
392 }
393 EXPORT_SYMBOL_GPL(rtc_update_irq);
394
395 static int __rtc_match(struct device *dev, void *data)
396 {
397 char *name = (char *)data;
398
399 if (strcmp(dev_name(dev), name) == 0)
400 return 1;
401 return 0;
402 }
403
404 struct rtc_device *rtc_class_open(char *name)
405 {
406 struct device *dev;
407 struct rtc_device *rtc = NULL;
408
409 dev = class_find_device(rtc_class, NULL, name, __rtc_match);
410 if (dev)
411 rtc = to_rtc_device(dev);
412
413 if (rtc) {
414 if (!try_module_get(rtc->owner)) {
415 put_device(dev);
416 rtc = NULL;
417 }
418 }
419
420 return rtc;
421 }
422 EXPORT_SYMBOL_GPL(rtc_class_open);
423
424 void rtc_class_close(struct rtc_device *rtc)
425 {
426 module_put(rtc->owner);
427 put_device(&rtc->dev);
428 }
429 EXPORT_SYMBOL_GPL(rtc_class_close);
430
431 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
432 {
433 int retval = -EBUSY;
434
435 if (task == NULL || task->func == NULL)
436 return -EINVAL;
437
438 /* Cannot register while the char dev is in use */
439 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
440 return -EBUSY;
441
442 spin_lock_irq(&rtc->irq_task_lock);
443 if (rtc->irq_task == NULL) {
444 rtc->irq_task = task;
445 retval = 0;
446 }
447 spin_unlock_irq(&rtc->irq_task_lock);
448
449 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
450
451 return retval;
452 }
453 EXPORT_SYMBOL_GPL(rtc_irq_register);
454
455 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
456 {
457 spin_lock_irq(&rtc->irq_task_lock);
458 if (rtc->irq_task == task)
459 rtc->irq_task = NULL;
460 spin_unlock_irq(&rtc->irq_task_lock);
461 }
462 EXPORT_SYMBOL_GPL(rtc_irq_unregister);
463
464 /**
465 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
466 * @rtc: the rtc device
467 * @task: currently registered with rtc_irq_register()
468 * @enabled: true to enable periodic IRQs
469 * Context: any
470 *
471 * Note that rtc_irq_set_freq() should previously have been used to
472 * specify the desired frequency of periodic IRQ task->func() callbacks.
473 */
474 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
475 {
476 int err = 0;
477 unsigned long flags;
478
479 if (rtc->ops->irq_set_state == NULL)
480 return -ENXIO;
481
482 spin_lock_irqsave(&rtc->irq_task_lock, flags);
483 if (rtc->irq_task != NULL && task == NULL)
484 err = -EBUSY;
485 if (rtc->irq_task != task)
486 err = -EACCES;
487 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
488
489 if (err == 0)
490 err = rtc->ops->irq_set_state(rtc->dev.parent, enabled);
491
492 return err;
493 }
494 EXPORT_SYMBOL_GPL(rtc_irq_set_state);
495
496 /**
497 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
498 * @rtc: the rtc device
499 * @task: currently registered with rtc_irq_register()
500 * @freq: positive frequency with which task->func() will be called
501 * Context: any
502 *
503 * Note that rtc_irq_set_state() is used to enable or disable the
504 * periodic IRQs.
505 */
506 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
507 {
508 int err = 0;
509 unsigned long flags;
510
511 if (rtc->ops->irq_set_freq == NULL)
512 return -ENXIO;
513
514 spin_lock_irqsave(&rtc->irq_task_lock, flags);
515 if (rtc->irq_task != NULL && task == NULL)
516 err = -EBUSY;
517 if (rtc->irq_task != task)
518 err = -EACCES;
519 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
520
521 if (err == 0) {
522 err = rtc->ops->irq_set_freq(rtc->dev.parent, freq);
523 if (err == 0)
524 rtc->irq_freq = freq;
525 }
526 return err;
527 }
528 EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
529
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