Linux 2.6.34-rc3
[pohmelfs.git] / drivers / rtc / rtc-ds1374.c
blob5317bbcbc7a0c7cb3f60e16e6bafac483327a666
1 /*
2 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
4 * Based on code by Randy Vinson <rvinson@mvista.com>,
5 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
7 * Copyright (C) 2006-2007 Freescale Semiconductor
9 * 2005 (c) MontaVista Software, Inc. This file is licensed under
10 * the terms of the GNU General Public License version 2. This program
11 * is licensed "as is" without any warranty of any kind, whether express
12 * or implied.
15 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
16 * recommened in .../Documentation/i2c/writing-clients section
17 * "Sending and receiving", using SMBus level communication is preferred.
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/interrupt.h>
23 #include <linux/i2c.h>
24 #include <linux/rtc.h>
25 #include <linux/bcd.h>
26 #include <linux/workqueue.h>
28 #define DS1374_REG_TOD0 0x00 /* Time of Day */
29 #define DS1374_REG_TOD1 0x01
30 #define DS1374_REG_TOD2 0x02
31 #define DS1374_REG_TOD3 0x03
32 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */
33 #define DS1374_REG_WDALM1 0x05
34 #define DS1374_REG_WDALM2 0x06
35 #define DS1374_REG_CR 0x07 /* Control */
36 #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */
37 #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */
38 #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */
39 #define DS1374_REG_SR 0x08 /* Status */
40 #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */
41 #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */
42 #define DS1374_REG_TCR 0x09 /* Trickle Charge */
44 static const struct i2c_device_id ds1374_id[] = {
45 { "ds1374", 0 },
46 { }
48 MODULE_DEVICE_TABLE(i2c, ds1374_id);
50 struct ds1374 {
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.
59 struct mutex mutex;
60 int exiting;
63 static struct i2c_driver ds1374_driver;
65 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
66 int reg, int nbytes)
68 u8 buf[4];
69 int ret;
70 int i;
72 if (nbytes > 4) {
73 WARN_ON(1);
74 return -EINVAL;
77 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
79 if (ret < 0)
80 return ret;
81 if (ret < nbytes)
82 return -EIO;
84 for (i = nbytes - 1, *time = 0; i >= 0; i--)
85 *time = (*time << 8) | buf[i];
87 return 0;
90 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
91 int reg, int nbytes)
93 u8 buf[4];
94 int i;
96 if (nbytes > 4) {
97 WARN_ON(1);
98 return -EINVAL;
101 for (i = 0; i < nbytes; i++) {
102 buf[i] = time & 0xff;
103 time >>= 8;
106 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
109 static int ds1374_check_rtc_status(struct i2c_client *client)
111 int ret = 0;
112 int control, stat;
114 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
115 if (stat < 0)
116 return stat;
118 if (stat & DS1374_REG_SR_OSF)
119 dev_warn(&client->dev,
120 "oscillator discontinuity flagged, "
121 "time unreliable\n");
123 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
125 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
126 if (ret < 0)
127 return ret;
129 /* If the alarm is pending, clear it before requesting
130 * the interrupt, so an interrupt event isn't reported
131 * before everything is initialized.
134 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
135 if (control < 0)
136 return control;
138 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
139 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
142 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
144 struct i2c_client *client = to_i2c_client(dev);
145 u32 itime;
146 int ret;
148 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
149 if (!ret)
150 rtc_time_to_tm(itime, time);
152 return ret;
155 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
157 struct i2c_client *client = to_i2c_client(dev);
158 unsigned long itime;
160 rtc_tm_to_time(time, &itime);
161 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
164 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
165 * If the time of day is changed, then the alarm will need to be
166 * reset.
168 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
170 struct i2c_client *client = to_i2c_client(dev);
171 struct ds1374 *ds1374 = i2c_get_clientdata(client);
172 u32 now, cur_alarm;
173 int cr, sr;
174 int ret = 0;
176 if (client->irq <= 0)
177 return -EINVAL;
179 mutex_lock(&ds1374->mutex);
181 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
182 if (ret < 0)
183 goto out;
185 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
186 if (ret < 0)
187 goto out;
189 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
190 if (ret)
191 goto out;
193 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
194 if (ret)
195 goto out;
197 rtc_time_to_tm(now + cur_alarm, &alarm->time);
198 alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
199 alarm->pending = !!(sr & DS1374_REG_SR_AF);
201 out:
202 mutex_unlock(&ds1374->mutex);
203 return ret;
206 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
208 struct i2c_client *client = to_i2c_client(dev);
209 struct ds1374 *ds1374 = i2c_get_clientdata(client);
210 struct rtc_time now;
211 unsigned long new_alarm, itime;
212 int cr;
213 int ret = 0;
215 if (client->irq <= 0)
216 return -EINVAL;
218 ret = ds1374_read_time(dev, &now);
219 if (ret < 0)
220 return ret;
222 rtc_tm_to_time(&alarm->time, &new_alarm);
223 rtc_tm_to_time(&now, &itime);
225 /* This can happen due to races, in addition to dates that are
226 * truly in the past. To avoid requiring the caller to check for
227 * races, dates in the past are assumed to be in the recent past
228 * (i.e. not something that we'd rather the caller know about via
229 * an error), and the alarm is set to go off as soon as possible.
231 if (time_before_eq(new_alarm, itime))
232 new_alarm = 1;
233 else
234 new_alarm -= itime;
236 mutex_lock(&ds1374->mutex);
238 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
239 if (ret < 0)
240 goto out;
242 /* Disable any existing alarm before setting the new one
243 * (or lack thereof). */
244 cr &= ~DS1374_REG_CR_WACE;
246 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
247 if (ret < 0)
248 goto out;
250 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
251 if (ret)
252 goto out;
254 if (alarm->enabled) {
255 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
256 cr &= ~DS1374_REG_CR_WDALM;
258 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
261 out:
262 mutex_unlock(&ds1374->mutex);
263 return ret;
266 static irqreturn_t ds1374_irq(int irq, void *dev_id)
268 struct i2c_client *client = dev_id;
269 struct ds1374 *ds1374 = i2c_get_clientdata(client);
271 disable_irq_nosync(irq);
272 schedule_work(&ds1374->work);
273 return IRQ_HANDLED;
276 static void ds1374_work(struct work_struct *work)
278 struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
279 struct i2c_client *client = ds1374->client;
280 int stat, control;
282 mutex_lock(&ds1374->mutex);
284 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
285 if (stat < 0)
286 goto unlock;
288 if (stat & DS1374_REG_SR_AF) {
289 stat &= ~DS1374_REG_SR_AF;
290 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
292 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
293 if (control < 0)
294 goto out;
296 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
297 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
299 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
302 out:
303 if (!ds1374->exiting)
304 enable_irq(client->irq);
305 unlock:
306 mutex_unlock(&ds1374->mutex);
309 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
311 struct i2c_client *client = to_i2c_client(dev);
312 struct ds1374 *ds1374 = i2c_get_clientdata(client);
313 int ret = -ENOIOCTLCMD;
315 mutex_lock(&ds1374->mutex);
317 switch (cmd) {
318 case RTC_AIE_OFF:
319 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
320 if (ret < 0)
321 goto out;
323 ret &= ~DS1374_REG_CR_WACE;
325 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
326 if (ret < 0)
327 goto out;
329 break;
331 case RTC_AIE_ON:
332 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
333 if (ret < 0)
334 goto out;
336 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
337 ret &= ~DS1374_REG_CR_WDALM;
339 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
340 if (ret < 0)
341 goto out;
343 break;
346 out:
347 mutex_unlock(&ds1374->mutex);
348 return ret;
351 static const struct rtc_class_ops ds1374_rtc_ops = {
352 .read_time = ds1374_read_time,
353 .set_time = ds1374_set_time,
354 .read_alarm = ds1374_read_alarm,
355 .set_alarm = ds1374_set_alarm,
356 .ioctl = ds1374_ioctl,
359 static int ds1374_probe(struct i2c_client *client,
360 const struct i2c_device_id *id)
362 struct ds1374 *ds1374;
363 int ret;
365 ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
366 if (!ds1374)
367 return -ENOMEM;
369 ds1374->client = client;
370 i2c_set_clientdata(client, ds1374);
372 INIT_WORK(&ds1374->work, ds1374_work);
373 mutex_init(&ds1374->mutex);
375 ret = ds1374_check_rtc_status(client);
376 if (ret)
377 goto out_free;
379 if (client->irq > 0) {
380 ret = request_irq(client->irq, ds1374_irq, 0,
381 "ds1374", client);
382 if (ret) {
383 dev_err(&client->dev, "unable to request IRQ\n");
384 goto out_free;
387 device_set_wakeup_capable(&client->dev, 1);
390 ds1374->rtc = rtc_device_register(client->name, &client->dev,
391 &ds1374_rtc_ops, THIS_MODULE);
392 if (IS_ERR(ds1374->rtc)) {
393 ret = PTR_ERR(ds1374->rtc);
394 dev_err(&client->dev, "unable to register the class device\n");
395 goto out_irq;
398 return 0;
400 out_irq:
401 if (client->irq > 0)
402 free_irq(client->irq, client);
404 out_free:
405 i2c_set_clientdata(client, NULL);
406 kfree(ds1374);
407 return ret;
410 static int __devexit ds1374_remove(struct i2c_client *client)
412 struct ds1374 *ds1374 = i2c_get_clientdata(client);
414 if (client->irq > 0) {
415 mutex_lock(&ds1374->mutex);
416 ds1374->exiting = 1;
417 mutex_unlock(&ds1374->mutex);
419 free_irq(client->irq, client);
420 flush_scheduled_work();
423 rtc_device_unregister(ds1374->rtc);
424 i2c_set_clientdata(client, NULL);
425 kfree(ds1374);
426 return 0;
429 #ifdef CONFIG_PM
430 static int ds1374_suspend(struct i2c_client *client, pm_message_t state)
432 if (client->irq >= 0 && device_may_wakeup(&client->dev))
433 enable_irq_wake(client->irq);
434 return 0;
437 static int ds1374_resume(struct i2c_client *client)
439 if (client->irq >= 0 && device_may_wakeup(&client->dev))
440 disable_irq_wake(client->irq);
441 return 0;
443 #else
444 #define ds1374_suspend NULL
445 #define ds1374_resume NULL
446 #endif
448 static struct i2c_driver ds1374_driver = {
449 .driver = {
450 .name = "rtc-ds1374",
451 .owner = THIS_MODULE,
453 .probe = ds1374_probe,
454 .suspend = ds1374_suspend,
455 .resume = ds1374_resume,
456 .remove = __devexit_p(ds1374_remove),
457 .id_table = ds1374_id,
460 static int __init ds1374_init(void)
462 return i2c_add_driver(&ds1374_driver);
465 static void __exit ds1374_exit(void)
467 i2c_del_driver(&ds1374_driver);
470 module_init(ds1374_init);
471 module_exit(ds1374_exit);
473 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
474 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
475 MODULE_LICENSE("GPL");