rtc: add support for Epson RTC-9701JE V2
[linux-2.6.git] / drivers / rtc / rtc-ds1374.c
1 /*
2  * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
3  *
4  * Based on code by Randy Vinson <rvinson@mvista.com>,
5  * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
6  *
7  * Copyright (C) 2006-2007 Freescale Semiconductor
8  *
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.
13  */
14 /*
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.
18  */
19
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>
27
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 */
43
44 struct ds1374 {
45         struct i2c_client *client;
46         struct rtc_device *rtc;
47         struct work_struct work;
48
49         /* The mutex protects alarm operations, and prevents a race
50          * between the enable_irq() in the workqueue and the free_irq()
51          * in the remove function.
52          */
53         struct mutex mutex;
54         int exiting;
55 };
56
57 static struct i2c_driver ds1374_driver;
58
59 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
60                            int reg, int nbytes)
61 {
62         u8 buf[4];
63         int ret;
64         int i;
65
66         if (nbytes > 4) {
67                 WARN_ON(1);
68                 return -EINVAL;
69         }
70
71         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
72
73         if (ret < 0)
74                 return ret;
75         if (ret < nbytes)
76                 return -EIO;
77
78         for (i = nbytes - 1, *time = 0; i >= 0; i--)
79                 *time = (*time << 8) | buf[i];
80
81         return 0;
82 }
83
84 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
85                             int reg, int nbytes)
86 {
87         u8 buf[4];
88         int i;
89
90         if (nbytes > 4) {
91                 WARN_ON(1);
92                 return -EINVAL;
93         }
94
95         for (i = 0; i < nbytes; i++) {
96                 buf[i] = time & 0xff;
97                 time >>= 8;
98         }
99
100         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
101 }
102
103 static int ds1374_check_rtc_status(struct i2c_client *client)
104 {
105         int ret = 0;
106         int control, stat;
107
108         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
109         if (stat < 0)
110                 return stat;
111
112         if (stat & DS1374_REG_SR_OSF)
113                 dev_warn(&client->dev,
114                          "oscillator discontinuity flagged, "
115                          "time unreliable\n");
116
117         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
118
119         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
120         if (ret < 0)
121                 return ret;
122
123         /* If the alarm is pending, clear it before requesting
124          * the interrupt, so an interrupt event isn't reported
125          * before everything is initialized.
126          */
127
128         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
129         if (control < 0)
130                 return control;
131
132         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
133         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
134 }
135
136 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
137 {
138         struct i2c_client *client = to_i2c_client(dev);
139         u32 itime;
140         int ret;
141
142         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
143         if (!ret)
144                 rtc_time_to_tm(itime, time);
145
146         return ret;
147 }
148
149 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
150 {
151         struct i2c_client *client = to_i2c_client(dev);
152         unsigned long itime;
153
154         rtc_tm_to_time(time, &itime);
155         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
156 }
157
158 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
159  * If the time of day is changed, then the alarm will need to be
160  * reset.
161  */
162 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
163 {
164         struct i2c_client *client = to_i2c_client(dev);
165         struct ds1374 *ds1374 = i2c_get_clientdata(client);
166         u32 now, cur_alarm;
167         int cr, sr;
168         int ret = 0;
169
170         if (client->irq < 0)
171                 return -EINVAL;
172
173         mutex_lock(&ds1374->mutex);
174
175         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
176         if (ret < 0)
177                 goto out;
178
179         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
180         if (ret < 0)
181                 goto out;
182
183         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
184         if (ret)
185                 goto out;
186
187         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
188         if (ret)
189                 goto out;
190
191         rtc_time_to_tm(now + cur_alarm, &alarm->time);
192         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
193         alarm->pending = !!(sr & DS1374_REG_SR_AF);
194
195 out:
196         mutex_unlock(&ds1374->mutex);
197         return ret;
198 }
199
200 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
201 {
202         struct i2c_client *client = to_i2c_client(dev);
203         struct ds1374 *ds1374 = i2c_get_clientdata(client);
204         struct rtc_time now;
205         unsigned long new_alarm, itime;
206         int cr;
207         int ret = 0;
208
209         if (client->irq < 0)
210                 return -EINVAL;
211
212         ret = ds1374_read_time(dev, &now);
213         if (ret < 0)
214                 return ret;
215
216         rtc_tm_to_time(&alarm->time, &new_alarm);
217         rtc_tm_to_time(&now, &itime);
218
219         new_alarm -= itime;
220
221         /* This can happen due to races, in addition to dates that are
222          * truly in the past.  To avoid requiring the caller to check for
223          * races, dates in the past are assumed to be in the recent past
224          * (i.e. not something that we'd rather the caller know about via
225          * an error), and the alarm is set to go off as soon as possible.
226          */
227         if (new_alarm <= 0)
228                 new_alarm = 1;
229
230         mutex_lock(&ds1374->mutex);
231
232         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
233         if (ret < 0)
234                 goto out;
235
236         /* Disable any existing alarm before setting the new one
237          * (or lack thereof). */
238         cr &= ~DS1374_REG_CR_WACE;
239
240         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
241         if (ret < 0)
242                 goto out;
243
244         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
245         if (ret)
246                 goto out;
247
248         if (alarm->enabled) {
249                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
250                 cr &= ~DS1374_REG_CR_WDALM;
251
252                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
253         }
254
255 out:
256         mutex_unlock(&ds1374->mutex);
257         return ret;
258 }
259
260 static irqreturn_t ds1374_irq(int irq, void *dev_id)
261 {
262         struct i2c_client *client = dev_id;
263         struct ds1374 *ds1374 = i2c_get_clientdata(client);
264
265         disable_irq_nosync(irq);
266         schedule_work(&ds1374->work);
267         return IRQ_HANDLED;
268 }
269
270 static void ds1374_work(struct work_struct *work)
271 {
272         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
273         struct i2c_client *client = ds1374->client;
274         int stat, control;
275
276         mutex_lock(&ds1374->mutex);
277
278         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
279         if (stat < 0)
280                 return;
281
282         if (stat & DS1374_REG_SR_AF) {
283                 stat &= ~DS1374_REG_SR_AF;
284                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
285
286                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
287                 if (control < 0)
288                         goto out;
289
290                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
291                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
292
293                 /* rtc_update_irq() assumes that it is called
294                  * from IRQ-disabled context.
295                  */
296                 local_irq_disable();
297                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
298                 local_irq_enable();
299         }
300
301 out:
302         if (!ds1374->exiting)
303                 enable_irq(client->irq);
304
305         mutex_unlock(&ds1374->mutex);
306 }
307
308 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
309 {
310         struct i2c_client *client = to_i2c_client(dev);
311         struct ds1374 *ds1374 = i2c_get_clientdata(client);
312         int ret = -ENOIOCTLCMD;
313
314         mutex_lock(&ds1374->mutex);
315
316         switch (cmd) {
317         case RTC_AIE_OFF:
318                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
319                 if (ret < 0)
320                         goto out;
321
322                 ret &= ~DS1374_REG_CR_WACE;
323
324                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
325                 if (ret < 0)
326                         goto out;
327
328                 break;
329
330         case RTC_AIE_ON:
331                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
332                 if (ret < 0)
333                         goto out;
334
335                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
336                 ret &= ~DS1374_REG_CR_WDALM;
337
338                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
339                 if (ret < 0)
340                         goto out;
341
342                 break;
343         }
344
345 out:
346         mutex_unlock(&ds1374->mutex);
347         return ret;
348 }
349
350 static const struct rtc_class_ops ds1374_rtc_ops = {
351         .read_time = ds1374_read_time,
352         .set_time = ds1374_set_time,
353         .read_alarm = ds1374_read_alarm,
354         .set_alarm = ds1374_set_alarm,
355         .ioctl = ds1374_ioctl,
356 };
357
358 static int ds1374_probe(struct i2c_client *client)
359 {
360         struct ds1374 *ds1374;
361         int ret;
362
363         ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
364         if (!ds1374)
365                 return -ENOMEM;
366
367         ds1374->client = client;
368         i2c_set_clientdata(client, ds1374);
369
370         INIT_WORK(&ds1374->work, ds1374_work);
371         mutex_init(&ds1374->mutex);
372
373         ret = ds1374_check_rtc_status(client);
374         if (ret)
375                 goto out_free;
376
377         if (client->irq >= 0) {
378                 ret = request_irq(client->irq, ds1374_irq, 0,
379                                   "ds1374", client);
380                 if (ret) {
381                         dev_err(&client->dev, "unable to request IRQ\n");
382                         goto out_free;
383                 }
384         }
385
386         ds1374->rtc = rtc_device_register(client->name, &client->dev,
387                                           &ds1374_rtc_ops, THIS_MODULE);
388         if (IS_ERR(ds1374->rtc)) {
389                 ret = PTR_ERR(ds1374->rtc);
390                 dev_err(&client->dev, "unable to register the class device\n");
391                 goto out_irq;
392         }
393
394         return 0;
395
396 out_irq:
397         if (client->irq >= 0)
398                 free_irq(client->irq, client);
399
400 out_free:
401         i2c_set_clientdata(client, NULL);
402         kfree(ds1374);
403         return ret;
404 }
405
406 static int __devexit ds1374_remove(struct i2c_client *client)
407 {
408         struct ds1374 *ds1374 = i2c_get_clientdata(client);
409
410         if (client->irq >= 0) {
411                 mutex_lock(&ds1374->mutex);
412                 ds1374->exiting = 1;
413                 mutex_unlock(&ds1374->mutex);
414
415                 free_irq(client->irq, client);
416                 flush_scheduled_work();
417         }
418
419         rtc_device_unregister(ds1374->rtc);
420         i2c_set_clientdata(client, NULL);
421         kfree(ds1374);
422         return 0;
423 }
424
425 static struct i2c_driver ds1374_driver = {
426         .driver = {
427                 .name = "rtc-ds1374",
428                 .owner = THIS_MODULE,
429         },
430         .probe = ds1374_probe,
431         .remove = __devexit_p(ds1374_remove),
432 };
433
434 static int __init ds1374_init(void)
435 {
436         return i2c_add_driver(&ds1374_driver);
437 }
438
439 static void __exit ds1374_exit(void)
440 {
441         i2c_del_driver(&ds1374_driver);
442 }
443
444 module_init(ds1374_init);
445 module_exit(ds1374_exit);
446
447 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
448 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
449 MODULE_LICENSE("GPL");