projects/linux·blob v2.6.28 · refs

470 lines · 11.6 KiB

1/*
2 * RTC subsystem, interface functions
3 *
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <[email protected]>
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
17int 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}
37EXPORT_SYMBOL_GPL(rtc_read_time);
38
39int 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 = -EINVAL;
55 else
56 err = rtc->ops->set_time(rtc->dev.parent, tm);
57
58 mutex_unlock(&rtc->ops_lock);
59 return err;
60}
61EXPORT_SYMBOL_GPL(rtc_set_time);
62
63int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs)
64{
65 int err;
66
67 err = mutex_lock_interruptible(&rtc->ops_lock);
68 if (err)
69 return err;
70
71 if (!rtc->ops)
72 err = -ENODEV;
73 else if (rtc->ops->set_mmss)
74 err = rtc->ops->set_mmss(rtc->dev.parent, secs);
75 else if (rtc->ops->read_time && rtc->ops->set_time) {
76 struct rtc_time new, old;
77
78 err = rtc->ops->read_time(rtc->dev.parent, &old);
79 if (err == 0) {
80 rtc_time_to_tm(secs, &new);
81
82 /*
83 * avoid writing when we're going to change the day of
84 * the month. We will retry in the next minute. This
85 * basically means that if the RTC must not drift
86 * by more than 1 minute in 11 minutes.
87 */
88 if (!((old.tm_hour == 23 && old.tm_min == 59) ||
89 (new.tm_hour == 23 && new.tm_min == 59)))
90 err = rtc->ops->set_time(rtc->dev.parent,
91 &new);
92 }
93 }
94 else
95 err = -EINVAL;
96
97 mutex_unlock(&rtc->ops_lock);
98
99 return err;
100}
101EXPORT_SYMBOL_GPL(rtc_set_mmss);
102
103static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
104{
105 int err;
106
107 err = mutex_lock_interruptible(&rtc->ops_lock);
108 if (err)
109 return err;
110
111 if (rtc->ops == NULL)
112 err = -ENODEV;
113 else if (!rtc->ops->read_alarm)
114 err = -EINVAL;
115 else {
116 memset(alarm, 0, sizeof(struct rtc_wkalrm));
117 err = rtc->ops->read_alarm(rtc->dev.parent, alarm);
118 }
119
120 mutex_unlock(&rtc->ops_lock);
121 return err;
122}
123
124int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
125{
126 int err;
127 struct rtc_time before, now;
128 int first_time = 1;
129 unsigned long t_now, t_alm;
130 enum { none, day, month, year } missing = none;
131 unsigned days;
132
133 /* The lower level RTC driver may return -1 in some fields,
134 * creating invalid alarm->time values, for reasons like:
135 *
136 * - The hardware may not be capable of filling them in;
137 * many alarms match only on time-of-day fields, not
138 * day/month/year calendar data.
139 *
140 * - Some hardware uses illegal values as "wildcard" match
141 * values, which non-Linux firmware (like a BIOS) may try
142 * to set up as e.g. "alarm 15 minutes after each hour".
143 * Linux uses only oneshot alarms.
144 *
145 * When we see that here, we deal with it by using values from
146 * a current RTC timestamp for any missing (-1) values. The
147 * RTC driver prevents "periodic alarm" modes.
148 *
149 * But this can be racey, because some fields of the RTC timestamp
150 * may have wrapped in the interval since we read the RTC alarm,
151 * which would lead to us inserting inconsistent values in place
152 * of the -1 fields.
153 *
154 * Reading the alarm and timestamp in the reverse sequence
155 * would have the same race condition, and not solve the issue.
156 *
157 * So, we must first read the RTC timestamp,
158 * then read the RTC alarm value,
159 * and then read a second RTC timestamp.
160 *
161 * If any fields of the second timestamp have changed
162 * when compared with the first timestamp, then we know
163 * our timestamp may be inconsistent with that used by
164 * the low-level rtc_read_alarm_internal() function.
165 *
166 * So, when the two timestamps disagree, we just loop and do
167 * the process again to get a fully consistent set of values.
168 *
169 * This could all instead be done in the lower level driver,
170 * but since more than one lower level RTC implementation needs it,
171 * then it's probably best best to do it here instead of there..
172 */
173
174 /* Get the "before" timestamp */
175 err = rtc_read_time(rtc, &before);
176 if (err < 0)
177 return err;
178 do {
179 if (!first_time)
180 memcpy(&before, &now, sizeof(struct rtc_time));
181 first_time = 0;
182
183 /* get the RTC alarm values, which may be incomplete */
184 err = rtc_read_alarm_internal(rtc, alarm);
185 if (err)
186 return err;
187 if (!alarm->enabled)
188 return 0;
189
190 /* full-function RTCs won't have such missing fields */
191 if (rtc_valid_tm(&alarm->time) == 0)
192 return 0;
193
194 /* get the "after" timestamp, to detect wrapped fields */
195 err = rtc_read_time(rtc, &now);
196 if (err < 0)
197 return err;
198
199 /* note that tm_sec is a "don't care" value here: */
200 } while ( before.tm_min != now.tm_min
201 || before.tm_hour != now.tm_hour
202 || before.tm_mon != now.tm_mon
203 || before.tm_year != now.tm_year);
204
205 /* Fill in the missing alarm fields using the timestamp; we
206 * know there's at least one since alarm->time is invalid.
207 */
208 if (alarm->time.tm_sec == -1)
209 alarm->time.tm_sec = now.tm_sec;
210 if (alarm->time.tm_min == -1)
211 alarm->time.tm_min = now.tm_min;
212 if (alarm->time.tm_hour == -1)
213 alarm->time.tm_hour = now.tm_hour;
214
215 /* For simplicity, only support date rollover for now */
216 if (alarm->time.tm_mday == -1) {
217 alarm->time.tm_mday = now.tm_mday;
218 missing = day;
219 }
220 if (alarm->time.tm_mon == -1) {
221 alarm->time.tm_mon = now.tm_mon;
222 if (missing == none)
223 missing = month;
224 }
225 if (alarm->time.tm_year == -1) {
226 alarm->time.tm_year = now.tm_year;
227 if (missing == none)
228 missing = year;
229 }
230
231 /* with luck, no rollover is needed */
232 rtc_tm_to_time(&now, &t_now);
233 rtc_tm_to_time(&alarm->time, &t_alm);
234 if (t_now < t_alm)
235 goto done;
236
237 switch (missing) {
238
239 /* 24 hour rollover ... if it's now 10am Monday, an alarm that
240 * that will trigger at 5am will do so at 5am Tuesday, which
241 * could also be in the next month or year. This is a common
242 * case, especially for PCs.
243 */
244 case day:
245 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "day");
246 t_alm += 24 * 60 * 60;
247 rtc_time_to_tm(t_alm, &alarm->time);
248 break;
249
250 /* Month rollover ... if it's the 31th, an alarm on the 3rd will
251 * be next month. An alarm matching on the 30th, 29th, or 28th
252 * may end up in the month after that! Many newer PCs support
253 * this type of alarm.
254 */
255 case month:
256 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "month");
257 do {
258 if (alarm->time.tm_mon < 11)
259 alarm->time.tm_mon++;
260 else {
261 alarm->time.tm_mon = 0;
262 alarm->time.tm_year++;
263 }
264 days = rtc_month_days(alarm->time.tm_mon,
265 alarm->time.tm_year);
266 } while (days < alarm->time.tm_mday);
267 break;
268
269 /* Year rollover ... easy except for leap years! */
270 case year:
271 dev_dbg(&rtc->dev, "alarm rollover: %s\n", "year");
272 do {
273 alarm->time.tm_year++;
274 } while (rtc_valid_tm(&alarm->time) != 0);
275 break;
276
277 default:
278 dev_warn(&rtc->dev, "alarm rollover not handled\n");
279 }
280
281done:
282 return 0;
283}
284EXPORT_SYMBOL_GPL(rtc_read_alarm);
285
286int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
287{
288 int err;
289
290 err = rtc_valid_tm(&alarm->time);
291 if (err != 0)
292 return err;
293
294 err = mutex_lock_interruptible(&rtc->ops_lock);
295 if (err)
296 return err;
297
298 if (!rtc->ops)
299 err = -ENODEV;
300 else if (!rtc->ops->set_alarm)
301 err = -EINVAL;
302 else
303 err = rtc->ops->set_alarm(rtc->dev.parent, alarm);
304
305 mutex_unlock(&rtc->ops_lock);
306 return err;
307}
308EXPORT_SYMBOL_GPL(rtc_set_alarm);
309
310/**
311 * rtc_update_irq - report RTC periodic, alarm, and/or update irqs
312 * @rtc: the rtc device
313 * @num: how many irqs are being reported (usually one)
314 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
315 * Context: in_interrupt(), irqs blocked
316 */
317void rtc_update_irq(struct rtc_device *rtc,
318 unsigned long num, unsigned long events)
319{
320 spin_lock(&rtc->irq_lock);
321 rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
322 spin_unlock(&rtc->irq_lock);
323
324 spin_lock(&rtc->irq_task_lock);
325 if (rtc->irq_task)
326 rtc->irq_task->func(rtc->irq_task->private_data);
327 spin_unlock(&rtc->irq_task_lock);
328
329 wake_up_interruptible(&rtc->irq_queue);
330 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
331}
332EXPORT_SYMBOL_GPL(rtc_update_irq);
333
334static int __rtc_match(struct device *dev, void *data)
335{
336 char *name = (char *)data;
337
338 if (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 0)
339 return 1;
340 return 0;
341}
342
343struct rtc_device *rtc_class_open(char *name)
344{
345 struct device *dev;
346 struct rtc_device *rtc = NULL;
347
348 dev = class_find_device(rtc_class, NULL, name, __rtc_match);
349 if (dev)
350 rtc = to_rtc_device(dev);
351
352 if (rtc) {
353 if (!try_module_get(rtc->owner)) {
354 put_device(dev);
355 rtc = NULL;
356 }
357 }
358
359 return rtc;
360}
361EXPORT_SYMBOL_GPL(rtc_class_open);
362
363void rtc_class_close(struct rtc_device *rtc)
364{
365 module_put(rtc->owner);
366 put_device(&rtc->dev);
367}
368EXPORT_SYMBOL_GPL(rtc_class_close);
369
370int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
371{
372 int retval = -EBUSY;
373
374 if (task == NULL || task->func == NULL)
375 return -EINVAL;
376
377 /* Cannot register while the char dev is in use */
378 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags))
379 return -EBUSY;
380
381 spin_lock_irq(&rtc->irq_task_lock);
382 if (rtc->irq_task == NULL) {
383 rtc->irq_task = task;
384 retval = 0;
385 }
386 spin_unlock_irq(&rtc->irq_task_lock);
387
388 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags);
389
390 return retval;
391}
392EXPORT_SYMBOL_GPL(rtc_irq_register);
393
394void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
395{
396 spin_lock_irq(&rtc->irq_task_lock);
397 if (rtc->irq_task == task)
398 rtc->irq_task = NULL;
399 spin_unlock_irq(&rtc->irq_task_lock);
400}
401EXPORT_SYMBOL_GPL(rtc_irq_unregister);
402
403/**
404 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs
405 * @rtc: the rtc device
406 * @task: currently registered with rtc_irq_register()
407 * @enabled: true to enable periodic IRQs
408 * Context: any
409 *
410 * Note that rtc_irq_set_freq() should previously have been used to
411 * specify the desired frequency of periodic IRQ task->func() callbacks.
412 */
413int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled)
414{
415 int err = 0;
416 unsigned long flags;
417
418 if (rtc->ops->irq_set_state == NULL)
419 return -ENXIO;
420
421 spin_lock_irqsave(&rtc->irq_task_lock, flags);
422 if (rtc->irq_task != NULL && task == NULL)
423 err = -EBUSY;
424 if (rtc->irq_task != task)
425 err = -EACCES;
426 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
427
428 if (err == 0)
429 err = rtc->ops->irq_set_state(rtc->dev.parent, enabled);
430
431 return err;
432}
433EXPORT_SYMBOL_GPL(rtc_irq_set_state);
434
435/**
436 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ
437 * @rtc: the rtc device
438 * @task: currently registered with rtc_irq_register()
439 * @freq: positive frequency with which task->func() will be called
440 * Context: any
441 *
442 * Note that rtc_irq_set_state() is used to enable or disable the
443 * periodic IRQs.
444 */
445int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq)
446{
447 int err = 0;
448 unsigned long flags;
449
450 if (rtc->ops->irq_set_freq == NULL)
451 return -ENXIO;
452
453 if (!is_power_of_2(freq))
454 return -EINVAL;
455
456 spin_lock_irqsave(&rtc->irq_task_lock, flags);
457 if (rtc->irq_task != NULL && task == NULL)
458 err = -EBUSY;
459 if (rtc->irq_task != task)
460 err = -EACCES;
461 spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
462
463 if (err == 0) {
464 err = rtc->ops->irq_set_freq(rtc->dev.parent, freq);
465 if (err == 0)
466 rtc->irq_freq = freq;
467 }
468 return err;
469}
470EXPORT_SYMBOL_GPL(rtc_irq_set_freq);