UPSTREAM Revert 3.9 "rtc: palmas: Add RTC driver Palmas series PMIC"
[linux-3.10.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 #include <linux/slab.h>
28 #include <linux/pm.h>
29
30 #define DS1374_REG_TOD0         0x00 /* Time of Day */
31 #define DS1374_REG_TOD1         0x01
32 #define DS1374_REG_TOD2         0x02
33 #define DS1374_REG_TOD3         0x03
34 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
35 #define DS1374_REG_WDALM1       0x05
36 #define DS1374_REG_WDALM2       0x06
37 #define DS1374_REG_CR           0x07 /* Control */
38 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
39 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
40 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
41 #define DS1374_REG_SR           0x08 /* Status */
42 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
43 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
44 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
45
46 static const struct i2c_device_id ds1374_id[] = {
47         { "ds1374", 0 },
48         { }
49 };
50 MODULE_DEVICE_TABLE(i2c, ds1374_id);
51
52 struct ds1374 {
53         struct i2c_client *client;
54         struct rtc_device *rtc;
55         struct work_struct work;
56
57         /* The mutex protects alarm operations, and prevents a race
58          * between the enable_irq() in the workqueue and the free_irq()
59          * in the remove function.
60          */
61         struct mutex mutex;
62         int exiting;
63 };
64
65 static struct i2c_driver ds1374_driver;
66
67 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
68                            int reg, int nbytes)
69 {
70         u8 buf[4];
71         int ret;
72         int i;
73
74         if (nbytes > 4) {
75                 WARN_ON(1);
76                 return -EINVAL;
77         }
78
79         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
80
81         if (ret < 0)
82                 return ret;
83         if (ret < nbytes)
84                 return -EIO;
85
86         for (i = nbytes - 1, *time = 0; i >= 0; i--)
87                 *time = (*time << 8) | buf[i];
88
89         return 0;
90 }
91
92 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
93                             int reg, int nbytes)
94 {
95         u8 buf[4];
96         int i;
97
98         if (nbytes > 4) {
99                 WARN_ON(1);
100                 return -EINVAL;
101         }
102
103         for (i = 0; i < nbytes; i++) {
104                 buf[i] = time & 0xff;
105                 time >>= 8;
106         }
107
108         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
109 }
110
111 static int ds1374_check_rtc_status(struct i2c_client *client)
112 {
113         int ret = 0;
114         int control, stat;
115
116         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
117         if (stat < 0)
118                 return stat;
119
120         if (stat & DS1374_REG_SR_OSF)
121                 dev_warn(&client->dev,
122                          "oscillator discontinuity flagged, "
123                          "time unreliable\n");
124
125         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
126
127         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
128         if (ret < 0)
129                 return ret;
130
131         /* If the alarm is pending, clear it before requesting
132          * the interrupt, so an interrupt event isn't reported
133          * before everything is initialized.
134          */
135
136         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
137         if (control < 0)
138                 return control;
139
140         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
141         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
142 }
143
144 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
145 {
146         struct i2c_client *client = to_i2c_client(dev);
147         u32 itime;
148         int ret;
149
150         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
151         if (!ret)
152                 rtc_time_to_tm(itime, time);
153
154         return ret;
155 }
156
157 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
158 {
159         struct i2c_client *client = to_i2c_client(dev);
160         unsigned long itime;
161
162         rtc_tm_to_time(time, &itime);
163         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
164 }
165
166 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
167  * If the time of day is changed, then the alarm will need to be
168  * reset.
169  */
170 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
171 {
172         struct i2c_client *client = to_i2c_client(dev);
173         struct ds1374 *ds1374 = i2c_get_clientdata(client);
174         u32 now, cur_alarm;
175         int cr, sr;
176         int ret = 0;
177
178         if (client->irq <= 0)
179                 return -EINVAL;
180
181         mutex_lock(&ds1374->mutex);
182
183         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
184         if (ret < 0)
185                 goto out;
186
187         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
188         if (ret < 0)
189                 goto out;
190
191         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
192         if (ret)
193                 goto out;
194
195         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
196         if (ret)
197                 goto out;
198
199         rtc_time_to_tm(now + cur_alarm, &alarm->time);
200         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
201         alarm->pending = !!(sr & DS1374_REG_SR_AF);
202
203 out:
204         mutex_unlock(&ds1374->mutex);
205         return ret;
206 }
207
208 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
209 {
210         struct i2c_client *client = to_i2c_client(dev);
211         struct ds1374 *ds1374 = i2c_get_clientdata(client);
212         struct rtc_time now;
213         unsigned long new_alarm, itime;
214         int cr;
215         int ret = 0;
216
217         if (client->irq <= 0)
218                 return -EINVAL;
219
220         ret = ds1374_read_time(dev, &now);
221         if (ret < 0)
222                 return ret;
223
224         rtc_tm_to_time(&alarm->time, &new_alarm);
225         rtc_tm_to_time(&now, &itime);
226
227         /* This can happen due to races, in addition to dates that are
228          * truly in the past.  To avoid requiring the caller to check for
229          * races, dates in the past are assumed to be in the recent past
230          * (i.e. not something that we'd rather the caller know about via
231          * an error), and the alarm is set to go off as soon as possible.
232          */
233         if (time_before_eq(new_alarm, itime))
234                 new_alarm = 1;
235         else
236                 new_alarm -= itime;
237
238         mutex_lock(&ds1374->mutex);
239
240         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
241         if (ret < 0)
242                 goto out;
243
244         /* Disable any existing alarm before setting the new one
245          * (or lack thereof). */
246         cr &= ~DS1374_REG_CR_WACE;
247
248         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
249         if (ret < 0)
250                 goto out;
251
252         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
253         if (ret)
254                 goto out;
255
256         if (alarm->enabled) {
257                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
258                 cr &= ~DS1374_REG_CR_WDALM;
259
260                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
261         }
262
263 out:
264         mutex_unlock(&ds1374->mutex);
265         return ret;
266 }
267
268 static irqreturn_t ds1374_irq(int irq, void *dev_id)
269 {
270         struct i2c_client *client = dev_id;
271         struct ds1374 *ds1374 = i2c_get_clientdata(client);
272
273         disable_irq_nosync(irq);
274         schedule_work(&ds1374->work);
275         return IRQ_HANDLED;
276 }
277
278 static void ds1374_work(struct work_struct *work)
279 {
280         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
281         struct i2c_client *client = ds1374->client;
282         int stat, control;
283
284         mutex_lock(&ds1374->mutex);
285
286         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
287         if (stat < 0)
288                 goto unlock;
289
290         if (stat & DS1374_REG_SR_AF) {
291                 stat &= ~DS1374_REG_SR_AF;
292                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
293
294                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
295                 if (control < 0)
296                         goto out;
297
298                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
299                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
300
301                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
302         }
303
304 out:
305         if (!ds1374->exiting)
306                 enable_irq(client->irq);
307 unlock:
308         mutex_unlock(&ds1374->mutex);
309 }
310
311 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
312 {
313         struct i2c_client *client = to_i2c_client(dev);
314         struct ds1374 *ds1374 = i2c_get_clientdata(client);
315         int ret;
316
317         mutex_lock(&ds1374->mutex);
318
319         ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
320         if (ret < 0)
321                 goto out;
322
323         if (enabled) {
324                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
325                 ret &= ~DS1374_REG_CR_WDALM;
326         } else {
327                 ret &= ~DS1374_REG_CR_WACE;
328         }
329         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
330
331 out:
332         mutex_unlock(&ds1374->mutex);
333         return ret;
334 }
335
336 static const struct rtc_class_ops ds1374_rtc_ops = {
337         .read_time = ds1374_read_time,
338         .set_time = ds1374_set_time,
339         .read_alarm = ds1374_read_alarm,
340         .set_alarm = ds1374_set_alarm,
341         .alarm_irq_enable = ds1374_alarm_irq_enable,
342 };
343
344 static int ds1374_probe(struct i2c_client *client,
345                         const struct i2c_device_id *id)
346 {
347         struct ds1374 *ds1374;
348         int ret;
349
350         ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
351         if (!ds1374)
352                 return -ENOMEM;
353
354         ds1374->client = client;
355         i2c_set_clientdata(client, ds1374);
356
357         INIT_WORK(&ds1374->work, ds1374_work);
358         mutex_init(&ds1374->mutex);
359
360         ret = ds1374_check_rtc_status(client);
361         if (ret)
362                 return ret;
363
364         if (client->irq > 0) {
365                 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
366                                   "ds1374", client);
367                 if (ret) {
368                         dev_err(&client->dev, "unable to request IRQ\n");
369                         return ret;
370                 }
371
372                 device_set_wakeup_capable(&client->dev, 1);
373         }
374
375         ds1374->rtc = devm_rtc_device_register(&client->dev, client->name,
376                                           &ds1374_rtc_ops, THIS_MODULE);
377         if (IS_ERR(ds1374->rtc)) {
378                 dev_err(&client->dev, "unable to register the class device\n");
379                 return PTR_ERR(ds1374->rtc);
380         }
381
382         return 0;
383 }
384
385 static int ds1374_remove(struct i2c_client *client)
386 {
387         struct ds1374 *ds1374 = i2c_get_clientdata(client);
388
389         if (client->irq > 0) {
390                 mutex_lock(&ds1374->mutex);
391                 ds1374->exiting = 1;
392                 mutex_unlock(&ds1374->mutex);
393
394                 devm_free_irq(&client->dev, client->irq, client);
395                 cancel_work_sync(&ds1374->work);
396         }
397
398         return 0;
399 }
400
401 #ifdef CONFIG_PM_SLEEP
402 static int ds1374_suspend(struct device *dev)
403 {
404         struct i2c_client *client = to_i2c_client(dev);
405
406         if (client->irq >= 0 && device_may_wakeup(&client->dev))
407                 enable_irq_wake(client->irq);
408         return 0;
409 }
410
411 static int ds1374_resume(struct device *dev)
412 {
413         struct i2c_client *client = to_i2c_client(dev);
414
415         if (client->irq >= 0 && device_may_wakeup(&client->dev))
416                 disable_irq_wake(client->irq);
417         return 0;
418 }
419 #endif
420
421 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
422
423 static struct i2c_driver ds1374_driver = {
424         .driver = {
425                 .name = "rtc-ds1374",
426                 .owner = THIS_MODULE,
427                 .pm = &ds1374_pm,
428         },
429         .probe = ds1374_probe,
430         .remove = ds1374_remove,
431         .id_table = ds1374_id,
432 };
433
434 module_i2c_driver(ds1374_driver);
435
436 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
437 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
438 MODULE_LICENSE("GPL");