2 * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
4 * Copyright (C) 2009-2010 Freescale Semiconductor.
5 * Author: Jack Lan <jack.lan@freescale.com>
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License as published by the
9 * Free Software Foundation; either version 2 of the License, or (at your
10 * option) any later version.
13 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
14 * recommened in .../Documentation/i2c/writing-clients section
15 * "Sending and receiving", using SMBus level communication is preferred.
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/interrupt.h>
21 #include <linux/i2c.h>
22 #include <linux/rtc.h>
23 #include <linux/bcd.h>
24 #include <linux/workqueue.h>
25 #include <linux/slab.h>
27 #define DS3232_REG_SECONDS 0x00
28 #define DS3232_REG_MINUTES 0x01
29 #define DS3232_REG_HOURS 0x02
30 #define DS3232_REG_AMPM 0x02
31 #define DS3232_REG_DAY 0x03
32 #define DS3232_REG_DATE 0x04
33 #define DS3232_REG_MONTH 0x05
34 #define DS3232_REG_CENTURY 0x05
35 #define DS3232_REG_YEAR 0x06
36 #define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */
37 #define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */
38 #define DS3232_REG_CR 0x0E /* Control register */
39 # define DS3232_REG_CR_nEOSC 0x80
40 # define DS3232_REG_CR_INTCN 0x04
41 # define DS3232_REG_CR_A2IE 0x02
42 # define DS3232_REG_CR_A1IE 0x01
44 #define DS3232_REG_SR 0x0F /* control/status register */
45 # define DS3232_REG_SR_OSF 0x80
46 # define DS3232_REG_SR_BSY 0x04
47 # define DS3232_REG_SR_A2F 0x02
48 # define DS3232_REG_SR_A1F 0x01
51 struct i2c_client *client;
52 struct rtc_device *rtc;
53 struct work_struct work;
55 /* The mutex protects alarm operations, and prevents a race
56 * between the enable_irq() in the workqueue and the free_irq()
57 * in the remove function.
63 static struct i2c_driver ds3232_driver;
65 static int ds3232_check_rtc_status(struct i2c_client *client)
70 stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
74 if (stat & DS3232_REG_SR_OSF)
75 dev_warn(&client->dev,
76 "oscillator discontinuity flagged, "
79 stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
81 ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
85 /* If the alarm is pending, clear it before requesting
86 * the interrupt, so an interrupt event isn't reported
87 * before everything is initialized.
90 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
94 control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
95 control |= DS3232_REG_CR_INTCN;
97 return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
100 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
102 struct i2c_client *client = to_i2c_client(dev);
105 unsigned int year, month, day, hour, minute, second;
106 unsigned int week, twelve_hr, am_pm;
107 unsigned int century, add_century = 0;
109 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
124 /* Extract additional information for AM/PM and century */
126 twelve_hr = hour & 0x40;
128 century = month & 0x80;
130 /* Write to rtc_time structure */
132 time->tm_sec = bcd2bin(second);
133 time->tm_min = bcd2bin(minute);
135 /* Convert to 24 hr */
137 time->tm_hour = bcd2bin(hour & 0x1F) + 12;
139 time->tm_hour = bcd2bin(hour & 0x1F);
141 time->tm_hour = bcd2bin(hour);
144 time->tm_wday = bcd2bin(week);
145 time->tm_mday = bcd2bin(day);
146 time->tm_mon = bcd2bin(month & 0x7F);
150 time->tm_year = bcd2bin(year) + add_century;
152 return rtc_valid_tm(time);
155 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
157 struct i2c_client *client = to_i2c_client(dev);
160 /* Extract time from rtc_time and load into ds3232*/
162 buf[0] = bin2bcd(time->tm_sec);
163 buf[1] = bin2bcd(time->tm_min);
164 buf[2] = bin2bcd(time->tm_hour);
165 buf[3] = bin2bcd(time->tm_wday); /* Day of the week */
166 buf[4] = bin2bcd(time->tm_mday); /* Date */
167 buf[5] = bin2bcd(time->tm_mon);
168 if (time->tm_year >= 100) {
170 buf[6] = bin2bcd(time->tm_year - 100);
172 buf[6] = bin2bcd(time->tm_year);
175 return i2c_smbus_write_i2c_block_data(client,
176 DS3232_REG_SECONDS, 7, buf);
180 * DS3232 has two alarm, we only use alarm1
181 * According to linux specification, only support one-shot alarm
182 * no periodic alarm mode
184 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
186 struct i2c_client *client = to_i2c_client(dev);
187 struct ds3232 *ds3232 = i2c_get_clientdata(client);
192 mutex_lock(&ds3232->mutex);
194 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
198 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
202 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
206 alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
207 alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
208 alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
209 alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);
211 alarm->time.tm_mon = -1;
212 alarm->time.tm_year = -1;
213 alarm->time.tm_wday = -1;
214 alarm->time.tm_yday = -1;
215 alarm->time.tm_isdst = -1;
217 alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
218 alarm->pending = !!(stat & DS3232_REG_SR_A1F);
222 mutex_unlock(&ds3232->mutex);
227 * linux rtc-module does not support wday alarm
228 * and only 24h time mode supported indeed
230 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
232 struct i2c_client *client = to_i2c_client(dev);
233 struct ds3232 *ds3232 = i2c_get_clientdata(client);
238 if (client->irq <= 0)
241 mutex_lock(&ds3232->mutex);
243 buf[0] = bin2bcd(alarm->time.tm_sec);
244 buf[1] = bin2bcd(alarm->time.tm_min);
245 buf[2] = bin2bcd(alarm->time.tm_hour);
246 buf[3] = bin2bcd(alarm->time.tm_mday);
248 /* clear alarm interrupt enable bit */
249 ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
253 control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
254 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
258 /* clear any pending alarm flag */
259 ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
263 stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
264 ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
268 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
270 if (alarm->enabled) {
271 control |= DS3232_REG_CR_A1IE;
272 ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
275 mutex_unlock(&ds3232->mutex);
279 static void ds3232_update_alarm(struct i2c_client *client)
281 struct ds3232 *ds3232 = i2c_get_clientdata(client);
286 mutex_lock(&ds3232->mutex);
288 ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
292 buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
294 buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
296 buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
298 buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
301 ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
305 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
309 if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
310 /* enable alarm1 interrupt */
311 control |= DS3232_REG_CR_A1IE;
313 /* disable alarm1 interrupt */
314 control &= ~(DS3232_REG_CR_A1IE);
315 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
318 mutex_unlock(&ds3232->mutex);
321 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
323 struct i2c_client *client = to_i2c_client(dev);
324 struct ds3232 *ds3232 = i2c_get_clientdata(client);
326 if (client->irq <= 0)
330 ds3232->rtc->irq_data |= RTC_AF;
332 ds3232->rtc->irq_data &= ~RTC_AF;
334 ds3232_update_alarm(client);
338 static int ds3232_update_irq_enable(struct device *dev, unsigned int enabled)
340 struct i2c_client *client = to_i2c_client(dev);
341 struct ds3232 *ds3232 = i2c_get_clientdata(client);
343 if (client->irq <= 0)
347 ds3232->rtc->irq_data |= RTC_UF;
349 ds3232->rtc->irq_data &= ~RTC_UF;
351 ds3232_update_alarm(client);
355 static irqreturn_t ds3232_irq(int irq, void *dev_id)
357 struct i2c_client *client = dev_id;
358 struct ds3232 *ds3232 = i2c_get_clientdata(client);
360 disable_irq_nosync(irq);
361 schedule_work(&ds3232->work);
365 static void ds3232_work(struct work_struct *work)
367 struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
368 struct i2c_client *client = ds3232->client;
371 mutex_lock(&ds3232->mutex);
373 stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
377 if (stat & DS3232_REG_SR_A1F) {
378 control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
381 /* disable alarm1 interrupt */
382 control &= ~(DS3232_REG_CR_A1IE);
383 i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
385 /* clear the alarm pend flag */
386 stat &= ~DS3232_REG_SR_A1F;
387 i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
389 rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
393 if (!ds3232->exiting)
394 enable_irq(client->irq);
396 mutex_unlock(&ds3232->mutex);
399 static const struct rtc_class_ops ds3232_rtc_ops = {
400 .read_time = ds3232_read_time,
401 .set_time = ds3232_set_time,
402 .read_alarm = ds3232_read_alarm,
403 .set_alarm = ds3232_set_alarm,
404 .alarm_irq_enable = ds3232_alarm_irq_enable,
405 .update_irq_enable = ds3232_update_irq_enable,
408 static int __devinit ds3232_probe(struct i2c_client *client,
409 const struct i2c_device_id *id)
411 struct ds3232 *ds3232;
414 ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
418 ds3232->client = client;
419 i2c_set_clientdata(client, ds3232);
421 INIT_WORK(&ds3232->work, ds3232_work);
422 mutex_init(&ds3232->mutex);
424 ret = ds3232_check_rtc_status(client);
428 ds3232->rtc = rtc_device_register(client->name, &client->dev,
429 &ds3232_rtc_ops, THIS_MODULE);
430 if (IS_ERR(ds3232->rtc)) {
431 ret = PTR_ERR(ds3232->rtc);
432 dev_err(&client->dev, "unable to register the class device\n");
436 if (client->irq >= 0) {
437 ret = request_irq(client->irq, ds3232_irq, 0,
440 dev_err(&client->dev, "unable to request IRQ\n");
448 if (client->irq >= 0)
449 free_irq(client->irq, client);
456 static int __devexit ds3232_remove(struct i2c_client *client)
458 struct ds3232 *ds3232 = i2c_get_clientdata(client);
460 if (client->irq >= 0) {
461 mutex_lock(&ds3232->mutex);
463 mutex_unlock(&ds3232->mutex);
465 free_irq(client->irq, client);
466 flush_scheduled_work();
469 rtc_device_unregister(ds3232->rtc);
474 static const struct i2c_device_id ds3232_id[] = {
478 MODULE_DEVICE_TABLE(i2c, ds3232_id);
480 static struct i2c_driver ds3232_driver = {
482 .name = "rtc-ds3232",
483 .owner = THIS_MODULE,
485 .probe = ds3232_probe,
486 .remove = __devexit_p(ds3232_remove),
487 .id_table = ds3232_id,
490 static int __init ds3232_init(void)
492 return i2c_add_driver(&ds3232_driver);
495 static void __exit ds3232_exit(void)
497 i2c_del_driver(&ds3232_driver);
500 module_init(ds3232_init);
501 module_exit(ds3232_exit);
503 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
504 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
505 MODULE_LICENSE("GPL");