rtc: don't use flush_scheduled_work()
[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 #include <linux/slab.h>
28
29 #define DS1374_REG_TOD0         0x00 /* Time of Day */
30 #define DS1374_REG_TOD1         0x01
31 #define DS1374_REG_TOD2         0x02
32 #define DS1374_REG_TOD3         0x03
33 #define DS1374_REG_WDALM0       0x04 /* Watchdog/Alarm */
34 #define DS1374_REG_WDALM1       0x05
35 #define DS1374_REG_WDALM2       0x06
36 #define DS1374_REG_CR           0x07 /* Control */
37 #define DS1374_REG_CR_AIE       0x01 /* Alarm Int. Enable */
38 #define DS1374_REG_CR_WDALM     0x20 /* 1=Watchdog, 0=Alarm */
39 #define DS1374_REG_CR_WACE      0x40 /* WD/Alarm counter enable */
40 #define DS1374_REG_SR           0x08 /* Status */
41 #define DS1374_REG_SR_OSF       0x80 /* Oscillator Stop Flag */
42 #define DS1374_REG_SR_AF        0x01 /* Alarm Flag */
43 #define DS1374_REG_TCR          0x09 /* Trickle Charge */
44
45 static const struct i2c_device_id ds1374_id[] = {
46         { "ds1374", 0 },
47         { }
48 };
49 MODULE_DEVICE_TABLE(i2c, ds1374_id);
50
51 struct ds1374 {
52         struct i2c_client *client;
53         struct rtc_device *rtc;
54         struct work_struct work;
55
56         /* The mutex protects alarm operations, and prevents a race
57          * between the enable_irq() in the workqueue and the free_irq()
58          * in the remove function.
59          */
60         struct mutex mutex;
61         int exiting;
62 };
63
64 static struct i2c_driver ds1374_driver;
65
66 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
67                            int reg, int nbytes)
68 {
69         u8 buf[4];
70         int ret;
71         int i;
72
73         if (nbytes > 4) {
74                 WARN_ON(1);
75                 return -EINVAL;
76         }
77
78         ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
79
80         if (ret < 0)
81                 return ret;
82         if (ret < nbytes)
83                 return -EIO;
84
85         for (i = nbytes - 1, *time = 0; i >= 0; i--)
86                 *time = (*time << 8) | buf[i];
87
88         return 0;
89 }
90
91 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
92                             int reg, int nbytes)
93 {
94         u8 buf[4];
95         int i;
96
97         if (nbytes > 4) {
98                 WARN_ON(1);
99                 return -EINVAL;
100         }
101
102         for (i = 0; i < nbytes; i++) {
103                 buf[i] = time & 0xff;
104                 time >>= 8;
105         }
106
107         return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
108 }
109
110 static int ds1374_check_rtc_status(struct i2c_client *client)
111 {
112         int ret = 0;
113         int control, stat;
114
115         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
116         if (stat < 0)
117                 return stat;
118
119         if (stat & DS1374_REG_SR_OSF)
120                 dev_warn(&client->dev,
121                          "oscillator discontinuity flagged, "
122                          "time unreliable\n");
123
124         stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
125
126         ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
127         if (ret < 0)
128                 return ret;
129
130         /* If the alarm is pending, clear it before requesting
131          * the interrupt, so an interrupt event isn't reported
132          * before everything is initialized.
133          */
134
135         control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
136         if (control < 0)
137                 return control;
138
139         control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
140         return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
141 }
142
143 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
144 {
145         struct i2c_client *client = to_i2c_client(dev);
146         u32 itime;
147         int ret;
148
149         ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
150         if (!ret)
151                 rtc_time_to_tm(itime, time);
152
153         return ret;
154 }
155
156 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
157 {
158         struct i2c_client *client = to_i2c_client(dev);
159         unsigned long itime;
160
161         rtc_tm_to_time(time, &itime);
162         return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
163 }
164
165 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
166  * If the time of day is changed, then the alarm will need to be
167  * reset.
168  */
169 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
170 {
171         struct i2c_client *client = to_i2c_client(dev);
172         struct ds1374 *ds1374 = i2c_get_clientdata(client);
173         u32 now, cur_alarm;
174         int cr, sr;
175         int ret = 0;
176
177         if (client->irq <= 0)
178                 return -EINVAL;
179
180         mutex_lock(&ds1374->mutex);
181
182         cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
183         if (ret < 0)
184                 goto out;
185
186         sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
187         if (ret < 0)
188                 goto out;
189
190         ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
191         if (ret)
192                 goto out;
193
194         ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
195         if (ret)
196                 goto out;
197
198         rtc_time_to_tm(now + cur_alarm, &alarm->time);
199         alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
200         alarm->pending = !!(sr & DS1374_REG_SR_AF);
201
202 out:
203         mutex_unlock(&ds1374->mutex);
204         return ret;
205 }
206
207 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
208 {
209         struct i2c_client *client = to_i2c_client(dev);
210         struct ds1374 *ds1374 = i2c_get_clientdata(client);
211         struct rtc_time now;
212         unsigned long new_alarm, itime;
213         int cr;
214         int ret = 0;
215
216         if (client->irq <= 0)
217                 return -EINVAL;
218
219         ret = ds1374_read_time(dev, &now);
220         if (ret < 0)
221                 return ret;
222
223         rtc_tm_to_time(&alarm->time, &new_alarm);
224         rtc_tm_to_time(&now, &itime);
225
226         /* This can happen due to races, in addition to dates that are
227          * truly in the past.  To avoid requiring the caller to check for
228          * races, dates in the past are assumed to be in the recent past
229          * (i.e. not something that we'd rather the caller know about via
230          * an error), and the alarm is set to go off as soon as possible.
231          */
232         if (time_before_eq(new_alarm, itime))
233                 new_alarm = 1;
234         else
235                 new_alarm -= itime;
236
237         mutex_lock(&ds1374->mutex);
238
239         ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
240         if (ret < 0)
241                 goto out;
242
243         /* Disable any existing alarm before setting the new one
244          * (or lack thereof). */
245         cr &= ~DS1374_REG_CR_WACE;
246
247         ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
248         if (ret < 0)
249                 goto out;
250
251         ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
252         if (ret)
253                 goto out;
254
255         if (alarm->enabled) {
256                 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
257                 cr &= ~DS1374_REG_CR_WDALM;
258
259                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
260         }
261
262 out:
263         mutex_unlock(&ds1374->mutex);
264         return ret;
265 }
266
267 static irqreturn_t ds1374_irq(int irq, void *dev_id)
268 {
269         struct i2c_client *client = dev_id;
270         struct ds1374 *ds1374 = i2c_get_clientdata(client);
271
272         disable_irq_nosync(irq);
273         schedule_work(&ds1374->work);
274         return IRQ_HANDLED;
275 }
276
277 static void ds1374_work(struct work_struct *work)
278 {
279         struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
280         struct i2c_client *client = ds1374->client;
281         int stat, control;
282
283         mutex_lock(&ds1374->mutex);
284
285         stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
286         if (stat < 0)
287                 goto unlock;
288
289         if (stat & DS1374_REG_SR_AF) {
290                 stat &= ~DS1374_REG_SR_AF;
291                 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
292
293                 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
294                 if (control < 0)
295                         goto out;
296
297                 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
298                 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
299
300                 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
301         }
302
303 out:
304         if (!ds1374->exiting)
305                 enable_irq(client->irq);
306 unlock:
307         mutex_unlock(&ds1374->mutex);
308 }
309
310 static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
311 {
312         struct i2c_client *client = to_i2c_client(dev);
313         struct ds1374 *ds1374 = i2c_get_clientdata(client);
314         int ret = -ENOIOCTLCMD;
315
316         mutex_lock(&ds1374->mutex);
317
318         switch (cmd) {
319         case RTC_AIE_OFF:
320                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
321                 if (ret < 0)
322                         goto out;
323
324                 ret &= ~DS1374_REG_CR_WACE;
325
326                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
327                 if (ret < 0)
328                         goto out;
329
330                 break;
331
332         case RTC_AIE_ON:
333                 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
334                 if (ret < 0)
335                         goto out;
336
337                 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
338                 ret &= ~DS1374_REG_CR_WDALM;
339
340                 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
341                 if (ret < 0)
342                         goto out;
343
344                 break;
345         }
346
347 out:
348         mutex_unlock(&ds1374->mutex);
349         return ret;
350 }
351
352 static const struct rtc_class_ops ds1374_rtc_ops = {
353         .read_time = ds1374_read_time,
354         .set_time = ds1374_set_time,
355         .read_alarm = ds1374_read_alarm,
356         .set_alarm = ds1374_set_alarm,
357         .ioctl = ds1374_ioctl,
358 };
359
360 static int ds1374_probe(struct i2c_client *client,
361                         const struct i2c_device_id *id)
362 {
363         struct ds1374 *ds1374;
364         int ret;
365
366         ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL);
367         if (!ds1374)
368                 return -ENOMEM;
369
370         ds1374->client = client;
371         i2c_set_clientdata(client, ds1374);
372
373         INIT_WORK(&ds1374->work, ds1374_work);
374         mutex_init(&ds1374->mutex);
375
376         ret = ds1374_check_rtc_status(client);
377         if (ret)
378                 goto out_free;
379
380         if (client->irq > 0) {
381                 ret = request_irq(client->irq, ds1374_irq, 0,
382                                   "ds1374", client);
383                 if (ret) {
384                         dev_err(&client->dev, "unable to request IRQ\n");
385                         goto out_free;
386                 }
387
388                 device_set_wakeup_capable(&client->dev, 1);
389         }
390
391         ds1374->rtc = rtc_device_register(client->name, &client->dev,
392                                           &ds1374_rtc_ops, THIS_MODULE);
393         if (IS_ERR(ds1374->rtc)) {
394                 ret = PTR_ERR(ds1374->rtc);
395                 dev_err(&client->dev, "unable to register the class device\n");
396                 goto out_irq;
397         }
398
399         return 0;
400
401 out_irq:
402         if (client->irq > 0)
403                 free_irq(client->irq, client);
404
405 out_free:
406         kfree(ds1374);
407         return ret;
408 }
409
410 static int __devexit ds1374_remove(struct i2c_client *client)
411 {
412         struct ds1374 *ds1374 = i2c_get_clientdata(client);
413
414         if (client->irq > 0) {
415                 mutex_lock(&ds1374->mutex);
416                 ds1374->exiting = 1;
417                 mutex_unlock(&ds1374->mutex);
418
419                 free_irq(client->irq, client);
420                 cancel_work_sync(&ds1374->work);
421         }
422
423         rtc_device_unregister(ds1374->rtc);
424         kfree(ds1374);
425         return 0;
426 }
427
428 #ifdef CONFIG_PM
429 static int ds1374_suspend(struct i2c_client *client, pm_message_t state)
430 {
431         if (client->irq >= 0 && device_may_wakeup(&client->dev))
432                 enable_irq_wake(client->irq);
433         return 0;
434 }
435
436 static int ds1374_resume(struct i2c_client *client)
437 {
438         if (client->irq >= 0 && device_may_wakeup(&client->dev))
439                 disable_irq_wake(client->irq);
440         return 0;
441 }
442 #else
443 #define ds1374_suspend  NULL
444 #define ds1374_resume   NULL
445 #endif
446
447 static struct i2c_driver ds1374_driver = {
448         .driver = {
449                 .name = "rtc-ds1374",
450                 .owner = THIS_MODULE,
451         },
452         .probe = ds1374_probe,
453         .suspend = ds1374_suspend,
454         .resume = ds1374_resume,
455         .remove = __devexit_p(ds1374_remove),
456         .id_table = ds1374_id,
457 };
458
459 static int __init ds1374_init(void)
460 {
461         return i2c_add_driver(&ds1374_driver);
462 }
463
464 static void __exit ds1374_exit(void)
465 {
466         i2c_del_driver(&ds1374_driver);
467 }
468
469 module_init(ds1374_init);
470 module_exit(ds1374_exit);
471
472 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
473 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
474 MODULE_LICENSE("GPL");