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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 | #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 = kzalloc(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 | goto out_free; |
363 | |
364 | if (client->irq > 0) { |
365 | ret = request_irq(client->irq, ds1374_irq, 0, |
366 | "ds1374", client); |
367 | if (ret) { |
368 | dev_err(&client->dev, "unable to request IRQ\n"); |
369 | goto out_free; |
370 | } |
371 | |
372 | device_set_wakeup_capable(&client->dev, 1); |
373 | } |
374 | |
375 | ds1374->rtc = rtc_device_register(client->name, &client->dev, |
376 | &ds1374_rtc_ops, THIS_MODULE); |
377 | if (IS_ERR(ds1374->rtc)) { |
378 | ret = PTR_ERR(ds1374->rtc); |
379 | dev_err(&client->dev, "unable to register the class device\n"); |
380 | goto out_irq; |
381 | } |
382 | |
383 | return 0; |
384 | |
385 | out_irq: |
386 | if (client->irq > 0) |
387 | free_irq(client->irq, client); |
388 | |
389 | out_free: |
390 | kfree(ds1374); |
391 | return ret; |
392 | } |
393 | |
394 | static int ds1374_remove(struct i2c_client *client) |
395 | { |
396 | struct ds1374 *ds1374 = i2c_get_clientdata(client); |
397 | |
398 | if (client->irq > 0) { |
399 | mutex_lock(&ds1374->mutex); |
400 | ds1374->exiting = 1; |
401 | mutex_unlock(&ds1374->mutex); |
402 | |
403 | free_irq(client->irq, client); |
404 | cancel_work_sync(&ds1374->work); |
405 | } |
406 | |
407 | rtc_device_unregister(ds1374->rtc); |
408 | kfree(ds1374); |
409 | return 0; |
410 | } |
411 | |
412 | #ifdef CONFIG_PM |
413 | static int ds1374_suspend(struct device *dev) |
414 | { |
415 | struct i2c_client *client = to_i2c_client(dev); |
416 | |
417 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
418 | enable_irq_wake(client->irq); |
419 | return 0; |
420 | } |
421 | |
422 | static int ds1374_resume(struct device *dev) |
423 | { |
424 | struct i2c_client *client = to_i2c_client(dev); |
425 | |
426 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
427 | disable_irq_wake(client->irq); |
428 | return 0; |
429 | } |
430 | |
431 | static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); |
432 | |
433 | #define DS1374_PM (&ds1374_pm) |
434 | #else |
435 | #define DS1374_PM NULL |
436 | #endif |
437 | |
438 | static struct i2c_driver ds1374_driver = { |
439 | .driver = { |
440 | .name = "rtc-ds1374", |
441 | .owner = THIS_MODULE, |
442 | .pm = DS1374_PM, |
443 | }, |
444 | .probe = ds1374_probe, |
445 | .remove = ds1374_remove, |
446 | .id_table = ds1374_id, |
447 | }; |
448 | |
449 | module_i2c_driver(ds1374_driver); |
450 | |
451 | MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); |
452 | MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); |
453 | MODULE_LICENSE("GPL"); |
454 |
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