4d32e328f6cd6b7bb2e9cf9e72748b6031f30ef6
[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 static const struct i2c_device_id ds1374_id[] = {
45         { "ds1374", 0 },
46         { }
47 };
48 MODULE_DEVICE_TABLE(i2c, ds1374_id);
49
50 struct ds1374 {
51         struct i2c_client *client;
52         struct rtc_device *rtc;
53         struct work_struct work;
54
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.
58          */
59         struct mutex mutex;
60         int exiting;
61 };
62
63 static struct i2c_driver ds1374_driver;
64
65 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
66                            int reg, int nbytes)
67 {
68         u8 buf[4];
69         int ret;
70         int i;
71
72         if (nbytes > 4) {
73                 WARN_ON(1);
74                 return -EINVAL;
75         }
76
77         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
78
79         if (ret < 0)
80                 return ret;
81         if (ret < nbytes)
82                 return -EIO;
83
84         for (i = nbytes - 1, *time = 0; i >= 0; i--)
85                 *time = (*time << 8) | buf[i];
86
87         return 0;
88 }
89
90 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
91                             int reg, int nbytes)
92 {
93         u8 buf[4];
94         int i;
95
96         if (nbytes > 4) {
97                 WARN_ON(1);
98                 return -EINVAL;
99         }
100
101         for (i = 0; i < nbytes; i++) {
102                 buf[i] = time & 0xff;
103                 time >>= 8;
104         }
105
106         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
107 }
108
109 static int ds1374_check_rtc_status(struct i2c_client *client)
110 {
111         int ret = 0;
112         int control, stat;
113
114         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
115         if (stat < 0)
116                 return stat;
117
118         if (stat & DS1374_REG_SR_OSF)
119                 dev_warn(&client->dev,
120                          "oscillator discontinuity flagged, "
121                          "time unreliable\n");
122
123         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
124
125         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
126         if (ret < 0)
127                 return ret;
128
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.
132          */
133
134         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
135         if (control < 0)
136                 return control;
137
138         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
139         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
140 }
141
142 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
143 {
144         struct i2c_client *client = to_i2c_client(dev);
145         u32 itime;
146         int ret;
147
148         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
149         if (!ret)
150                 rtc_time_to_tm(itime, time);
151
152         return ret;
153 }
154
155 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
156 {
157         struct i2c_client *client = to_i2c_client(dev);
158         unsigned long itime;
159
160         rtc_tm_to_time(time, &itime);
161         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
162 }
163
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.
167  */
168 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
169 {
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;
175
176         if (client->irq <= 0)
177                 return -EINVAL;
178
179         mutex_lock(&ds1374->mutex);
180
181         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
182         if (ret < 0)
183                 goto out;
184
185         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
186         if (ret < 0)
187                 goto out;
188
189         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
190         if (ret)
191                 goto out;
192
193         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
194         if (ret)
195                 goto out;
196
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);
200
201 out:
202         mutex_unlock(&ds1374->mutex);
203         return ret;
204 }
205
206 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
207 {
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;
214
215         if (client->irq <= 0)
216                 return -EINVAL;
217
218         ret = ds1374_read_time(dev, &now);
219         if (ret < 0)
220                 return ret;
221
222         rtc_tm_to_time(&alarm->time, &new_alarm);
223         rtc_tm_to_time(&now, &itime);
224
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.
230          */
231         if (time_before_eq(new_alarm, itime))
232                 new_alarm = 1;
233         else
234                 new_alarm -= itime;
235
236         mutex_lock(&ds1374->mutex);
237
238         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
239         if (ret < 0)
240                 goto out;
241
242         /* Disable any existing alarm before setting the new one
243          * (or lack thereof). */
244         cr &= ~DS1374_REG_CR_WACE;
245
246         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
247         if (ret < 0)
248                 goto out;
249
250         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
251         if (ret)
252                 goto out;
253
254         if (alarm->enabled) {
255                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
256                 cr &= ~DS1374_REG_CR_WDALM;
257
258                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
259         }
260
261 out:
262         mutex_unlock(&ds1374->mutex);
263         return ret;
264 }
265
266 static irqreturn_t ds1374_irq(int irq, void *dev_id)
267 {
268         struct i2c_client *client = dev_id;
269         struct ds1374 *ds1374 = i2c_get_clientdata(client);
270
271         disable_irq_nosync(irq);
272         schedule_work(&ds1374->work);
273         return IRQ_HANDLED;
274 }
275
276 static void ds1374_work(struct work_struct *work)
277 {
278         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
279         struct i2c_client *client = ds1374->client;
280         int stat, control;
281
282         mutex_lock(&ds1374->mutex);
283
284         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
285         if (stat < 0)
286                 return;
287
288         if (stat & DS1374_REG_SR_AF) {
289                 stat &= ~DS1374_REG_SR_AF;
290                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
291
292                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
293                 if (control < 0)
294                         goto out;
295
296                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
297                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
298
299                 /* rtc_update_irq() assumes that it is called
300                  * from IRQ-disabled context.
301                  */
302                 local_irq_disable();
303                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
304                 local_irq_enable();
305         }
306
307 out:
308         if (!ds1374->exiting)
309                 enable_irq(client->irq);
310
311         mutex_unlock(&ds1374->mutex);
312 }
313
314 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
315 {
316         struct i2c_client *client = to_i2c_client(dev);
317         struct ds1374 *ds1374 = i2c_get_clientdata(client);
318         int ret = -ENOIOCTLCMD;
319
320         mutex_lock(&ds1374->mutex);
321
322         switch (cmd) {
323         case RTC_AIE_OFF:
324                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
325                 if (ret < 0)
326                         goto out;
327
328                 ret &= ~DS1374_REG_CR_WACE;
329
330                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
331                 if (ret < 0)
332                         goto out;
333
334                 break;
335
336         case RTC_AIE_ON:
337                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
338                 if (ret < 0)
339                         goto out;
340
341                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
342                 ret &= ~DS1374_REG_CR_WDALM;
343
344                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
345                 if (ret < 0)
346                         goto out;
347
348                 break;
349         }
350
351 out:
352         mutex_unlock(&ds1374->mutex);
353         return ret;
354 }
355
356 static const struct rtc_class_ops ds1374_rtc_ops = {
357         .read_time = ds1374_read_time,
358         .set_time = ds1374_set_time,
359         .read_alarm = ds1374_read_alarm,
360         .set_alarm = ds1374_set_alarm,
361         .ioctl = ds1374_ioctl,
362 };
363
364 static int ds1374_probe(struct i2c_client *client,
365                         const struct i2c_device_id *id)
366 {
367         struct ds1374 *ds1374;
368         int ret;
369
370         ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
371         if (!ds1374)
372                 return -ENOMEM;
373
374         ds1374->client = client;
375         i2c_set_clientdata(client, ds1374);
376
377         INIT_WORK(&ds1374->work, ds1374_work);
378         mutex_init(&ds1374->mutex);
379
380         ret = ds1374_check_rtc_status(client);
381         if (ret)
382                 goto out_free;
383
384         if (client->irq > 0) {
385                 ret = request_irq(client->irq, ds1374_irq, 0,
386                                   "ds1374", client);
387                 if (ret) {
388                         dev_err(&client->dev, "unable to request IRQ\n");
389                         goto out_free;
390                 }
391         }
392
393         ds1374->rtc = rtc_device_register(client->name, &client->dev,
394                                           &ds1374_rtc_ops, THIS_MODULE);
395         if (IS_ERR(ds1374->rtc)) {
396                 ret = PTR_ERR(ds1374->rtc);
397                 dev_err(&client->dev, "unable to register the class device\n");
398                 goto out_irq;
399         }
400
401         return 0;
402
403 out_irq:
404         if (client->irq > 0)
405                 free_irq(client->irq, client);
406
407 out_free:
408         i2c_set_clientdata(client, NULL);
409         kfree(ds1374);
410         return ret;
411 }
412
413 static int __devexit ds1374_remove(struct i2c_client *client)
414 {
415         struct ds1374 *ds1374 = i2c_get_clientdata(client);
416
417         if (client->irq > 0) {
418                 mutex_lock(&ds1374->mutex);
419                 ds1374->exiting = 1;
420                 mutex_unlock(&ds1374->mutex);
421
422                 free_irq(client->irq, client);
423                 flush_scheduled_work();
424         }
425
426         rtc_device_unregister(ds1374->rtc);
427         i2c_set_clientdata(client, NULL);
428         kfree(ds1374);
429         return 0;
430 }
431
432 #ifdef CONFIG_PM
433 static int ds1374_suspend(struct i2c_client *client, pm_message_t state)
434 {
435         if (client->irq >= 0 && device_may_wakeup(&client->dev))
436                 enable_irq_wake(client->irq);
437         return 0;
438 }
439
440 static int ds1374_resume(struct i2c_client *client)
441 {
442         if (client->irq >= 0 && device_may_wakeup(&client->dev))
443                 disable_irq_wake(client->irq);
444         return 0;
445 }
446 #else
447 #define ds1374_suspend  NULL
448 #define ds1374_resume   NULL
449 #endif
450
451 static struct i2c_driver ds1374_driver = {
452         .driver = {
453                 .name = "rtc-ds1374",
454                 .owner = THIS_MODULE,
455         },
456         .probe = ds1374_probe,
457         .suspend = ds1374_suspend,
458         .resume = ds1374_resume,
459         .remove = __devexit_p(ds1374_remove),
460         .id_table = ds1374_id,
461 };
462
463 static int __init ds1374_init(void)
464 {
465         return i2c_add_driver(&ds1374_driver);
466 }
467
468 static void __exit ds1374_exit(void)
469 {
470         i2c_del_driver(&ds1374_driver);
471 }
472
473 module_init(ds1374_init);
474 module_exit(ds1374_exit);
475
476 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
477 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
478 MODULE_LICENSE("GPL");