2 * RTC subsystem, interface functions
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 * based on arch/arm/common/rtctime.c
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.
14 #include <linux/rtc.h>
15 #include <linux/log2.h>
17 int rtc_read_time(struct rtc_device
*rtc
, struct rtc_time
*tm
)
21 err
= mutex_lock_interruptible(&rtc
->ops_lock
);
27 else if (!rtc
->ops
->read_time
)
30 memset(tm
, 0, sizeof(struct rtc_time
));
31 err
= rtc
->ops
->read_time(rtc
->dev
.parent
, tm
);
34 mutex_unlock(&rtc
->ops_lock
);
37 EXPORT_SYMBOL_GPL(rtc_read_time
);
39 int rtc_set_time(struct rtc_device
*rtc
, struct rtc_time
*tm
)
43 err
= rtc_valid_tm(tm
);
47 err
= mutex_lock_interruptible(&rtc
->ops_lock
);
53 else if (!rtc
->ops
->set_time
)
56 err
= rtc
->ops
->set_time(rtc
->dev
.parent
, tm
);
58 mutex_unlock(&rtc
->ops_lock
);
61 EXPORT_SYMBOL_GPL(rtc_set_time
);
63 int rtc_set_mmss(struct rtc_device
*rtc
, unsigned long secs
)
67 err
= mutex_lock_interruptible(&rtc
->ops_lock
);
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
;
78 err
= rtc
->ops
->read_time(rtc
->dev
.parent
, &old
);
80 rtc_time_to_tm(secs
, &new);
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.
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
,
97 mutex_unlock(&rtc
->ops_lock
);
101 EXPORT_SYMBOL_GPL(rtc_set_mmss
);
103 static int rtc_read_alarm_internal(struct rtc_device
*rtc
, struct rtc_wkalrm
*alarm
)
107 err
= mutex_lock_interruptible(&rtc
->ops_lock
);
111 if (rtc
->ops
== NULL
)
113 else if (!rtc
->ops
->read_alarm
)
116 memset(alarm
, 0, sizeof(struct rtc_wkalrm
));
117 err
= rtc
->ops
->read_alarm(rtc
->dev
.parent
, alarm
);
120 mutex_unlock(&rtc
->ops_lock
);
124 int rtc_read_alarm(struct rtc_device
*rtc
, struct rtc_wkalrm
*alarm
)
127 struct rtc_time before
, now
;
129 unsigned long t_now
, t_alm
;
130 enum { none
, day
, month
, year
} missing
= none
;
133 /* The lower level RTC driver may return -1 in some fields,
134 * creating invalid alarm->time values, for reasons like:
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.
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.
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.
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
154 * Reading the alarm and timestamp in the reverse sequence
155 * would have the same race condition, and not solve the issue.
157 * So, we must first read the RTC timestamp,
158 * then read the RTC alarm value,
159 * and then read a second RTC timestamp.
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.
166 * So, when the two timestamps disagree, we just loop and do
167 * the process again to get a fully consistent set of values.
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..
174 /* Get the "before" timestamp */
175 err
= rtc_read_time(rtc
, &before
);
180 memcpy(&before
, &now
, sizeof(struct rtc_time
));
183 /* get the RTC alarm values, which may be incomplete */
184 err
= rtc_read_alarm_internal(rtc
, alarm
);
190 /* full-function RTCs won't have such missing fields */
191 if (rtc_valid_tm(&alarm
->time
) == 0)
194 /* get the "after" timestamp, to detect wrapped fields */
195 err
= rtc_read_time(rtc
, &now
);
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
);
205 /* Fill in the missing alarm fields using the timestamp; we
206 * know there's at least one since alarm->time is invalid.
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
;
215 /* For simplicity, only support date rollover for now */
216 if (alarm
->time
.tm_mday
== -1) {
217 alarm
->time
.tm_mday
= now
.tm_mday
;
220 if (alarm
->time
.tm_mon
== -1) {
221 alarm
->time
.tm_mon
= now
.tm_mon
;
225 if (alarm
->time
.tm_year
== -1) {
226 alarm
->time
.tm_year
= now
.tm_year
;
231 /* with luck, no rollover is needed */
232 rtc_tm_to_time(&now
, &t_now
);
233 rtc_tm_to_time(&alarm
->time
, &t_alm
);
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.
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
);
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.
256 dev_dbg(&rtc
->dev
, "alarm rollover: %s\n", "month");
258 if (alarm
->time
.tm_mon
< 11)
259 alarm
->time
.tm_mon
++;
261 alarm
->time
.tm_mon
= 0;
262 alarm
->time
.tm_year
++;
264 days
= rtc_month_days(alarm
->time
.tm_mon
,
265 alarm
->time
.tm_year
);
266 } while (days
< alarm
->time
.tm_mday
);
269 /* Year rollover ... easy except for leap years! */
271 dev_dbg(&rtc
->dev
, "alarm rollover: %s\n", "year");
273 alarm
->time
.tm_year
++;
274 } while (!rtc_valid_tm(&alarm
->time
));
278 dev_warn(&rtc
->dev
, "alarm rollover not handled\n");
284 EXPORT_SYMBOL_GPL(rtc_read_alarm
);
286 int rtc_set_alarm(struct rtc_device
*rtc
, struct rtc_wkalrm
*alarm
)
290 err
= rtc_valid_tm(&alarm
->time
);
294 err
= mutex_lock_interruptible(&rtc
->ops_lock
);
300 else if (!rtc
->ops
->set_alarm
)
303 err
= rtc
->ops
->set_alarm(rtc
->dev
.parent
, alarm
);
305 mutex_unlock(&rtc
->ops_lock
);
308 EXPORT_SYMBOL_GPL(rtc_set_alarm
);
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
317 void rtc_update_irq(struct rtc_device
*rtc
,
318 unsigned long num
, unsigned long events
)
320 spin_lock(&rtc
->irq_lock
);
321 rtc
->irq_data
= (rtc
->irq_data
+ (num
<< 8)) | events
;
322 spin_unlock(&rtc
->irq_lock
);
324 spin_lock(&rtc
->irq_task_lock
);
326 rtc
->irq_task
->func(rtc
->irq_task
->private_data
);
327 spin_unlock(&rtc
->irq_task_lock
);
329 wake_up_interruptible(&rtc
->irq_queue
);
330 kill_fasync(&rtc
->async_queue
, SIGIO
, POLL_IN
);
332 EXPORT_SYMBOL_GPL(rtc_update_irq
);
334 static int __rtc_match(struct device
*dev
, void *data
)
336 char *name
= (char *)data
;
338 if (strncmp(dev
->bus_id
, name
, BUS_ID_SIZE
) == 0)
343 struct rtc_device
*rtc_class_open(char *name
)
346 struct rtc_device
*rtc
= NULL
;
348 dev
= class_find_device(rtc_class
, name
, __rtc_match
);
350 rtc
= to_rtc_device(dev
);
353 if (!try_module_get(rtc
->owner
)) {
361 EXPORT_SYMBOL_GPL(rtc_class_open
);
363 void rtc_class_close(struct rtc_device
*rtc
)
365 module_put(rtc
->owner
);
366 put_device(&rtc
->dev
);
368 EXPORT_SYMBOL_GPL(rtc_class_close
);
370 int rtc_irq_register(struct rtc_device
*rtc
, struct rtc_task
*task
)
374 if (task
== NULL
|| task
->func
== NULL
)
377 /* Cannot register while the char dev is in use */
378 if (test_and_set_bit_lock(RTC_DEV_BUSY
, &rtc
->flags
))
381 spin_lock_irq(&rtc
->irq_task_lock
);
382 if (rtc
->irq_task
== NULL
) {
383 rtc
->irq_task
= task
;
386 spin_unlock_irq(&rtc
->irq_task_lock
);
388 clear_bit_unlock(RTC_DEV_BUSY
, &rtc
->flags
);
392 EXPORT_SYMBOL_GPL(rtc_irq_register
);
394 void rtc_irq_unregister(struct rtc_device
*rtc
, struct rtc_task
*task
)
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
);
401 EXPORT_SYMBOL_GPL(rtc_irq_unregister
);
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
410 * Note that rtc_irq_set_freq() should previously have been used to
411 * specify the desired frequency of periodic IRQ task->func() callbacks.
413 int rtc_irq_set_state(struct rtc_device
*rtc
, struct rtc_task
*task
, int enabled
)
418 if (rtc
->ops
->irq_set_state
== NULL
)
421 spin_lock_irqsave(&rtc
->irq_task_lock
, flags
);
422 if (rtc
->irq_task
!= NULL
&& task
== NULL
)
424 if (rtc
->irq_task
!= task
)
426 spin_unlock_irqrestore(&rtc
->irq_task_lock
, flags
);
429 err
= rtc
->ops
->irq_set_state(rtc
->dev
.parent
, enabled
);
433 EXPORT_SYMBOL_GPL(rtc_irq_set_state
);
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
442 * Note that rtc_irq_set_state() is used to enable or disable the
445 int rtc_irq_set_freq(struct rtc_device
*rtc
, struct rtc_task
*task
, int freq
)
450 if (rtc
->ops
->irq_set_freq
== NULL
)
453 if (!is_power_of_2(freq
))
456 spin_lock_irqsave(&rtc
->irq_task_lock
, flags
);
457 if (rtc
->irq_task
!= NULL
&& task
== NULL
)
459 if (rtc
->irq_task
!= task
)
461 spin_unlock_irqrestore(&rtc
->irq_task_lock
, flags
);
464 err
= rtc
->ops
->irq_set_freq(rtc
->dev
.parent
, freq
);
466 rtc
->irq_freq
= freq
;
470 EXPORT_SYMBOL_GPL(rtc_irq_set_freq
);
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