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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 | i2c_set_clientdata(client, NULL); |
407 | kfree(ds1374); |
408 | return ret; |
409 | } |
410 | |
411 | static int __devexit ds1374_remove(struct i2c_client *client) |
412 | { |
413 | struct ds1374 *ds1374 = i2c_get_clientdata(client); |
414 | |
415 | if (client->irq > 0) { |
416 | mutex_lock(&ds1374->mutex); |
417 | ds1374->exiting = 1; |
418 | mutex_unlock(&ds1374->mutex); |
419 | |
420 | free_irq(client->irq, client); |
421 | flush_scheduled_work(); |
422 | } |
423 | |
424 | rtc_device_unregister(ds1374->rtc); |
425 | i2c_set_clientdata(client, NULL); |
426 | kfree(ds1374); |
427 | return 0; |
428 | } |
429 | |
430 | #ifdef CONFIG_PM |
431 | static int ds1374_suspend(struct i2c_client *client, pm_message_t state) |
432 | { |
433 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
434 | enable_irq_wake(client->irq); |
435 | return 0; |
436 | } |
437 | |
438 | static int ds1374_resume(struct i2c_client *client) |
439 | { |
440 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
441 | disable_irq_wake(client->irq); |
442 | return 0; |
443 | } |
444 | #else |
445 | #define ds1374_suspend NULL |
446 | #define ds1374_resume NULL |
447 | #endif |
448 | |
449 | static struct i2c_driver ds1374_driver = { |
450 | .driver = { |
451 | .name = "rtc-ds1374", |
452 | .owner = THIS_MODULE, |
453 | }, |
454 | .probe = ds1374_probe, |
455 | .suspend = ds1374_suspend, |
456 | .resume = ds1374_resume, |
457 | .remove = __devexit_p(ds1374_remove), |
458 | .id_table = ds1374_id, |
459 | }; |
460 | |
461 | static int __init ds1374_init(void) |
462 | { |
463 | return i2c_add_driver(&ds1374_driver); |
464 | } |
465 | |
466 | static void __exit ds1374_exit(void) |
467 | { |
468 | i2c_del_driver(&ds1374_driver); |
469 | } |
470 | |
471 | module_init(ds1374_init); |
472 | module_exit(ds1374_exit); |
473 | |
474 | MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); |
475 | MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); |
476 | MODULE_LICENSE("GPL"); |
477 |
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