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bf4994d7 SW |
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> | |
5a0e3ad6 | 27 | #include <linux/slab.h> |
bc96ba74 | 28 | #include <linux/pm.h> |
bf4994d7 SW |
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 | ||
3760f736 | 46 | static const struct i2c_device_id ds1374_id[] = { |
f2eb4327 | 47 | { "ds1374", 0 }, |
3760f736 JD |
48 | { } |
49 | }; | |
50 | MODULE_DEVICE_TABLE(i2c, ds1374_id); | |
51 | ||
bf4994d7 SW |
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 | ||
b42f9317 | 178 | if (client->irq <= 0) |
bf4994d7 SW |
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 | ||
b42f9317 | 217 | if (client->irq <= 0) |
bf4994d7 SW |
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 | ||
bf4994d7 SW |
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 | */ | |
fa7af8b1 | 233 | if (time_before_eq(new_alarm, itime)) |
bf4994d7 | 234 | new_alarm = 1; |
fa7af8b1 RK |
235 | else |
236 | new_alarm -= itime; | |
bf4994d7 SW |
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) | |
28df30e6 | 288 | goto unlock; |
bf4994d7 SW |
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 | ||
bf4994d7 | 301 | rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); |
bf4994d7 SW |
302 | } |
303 | ||
304 | out: | |
305 | if (!ds1374->exiting) | |
306 | enable_irq(client->irq); | |
28df30e6 | 307 | unlock: |
bf4994d7 SW |
308 | mutex_unlock(&ds1374->mutex); |
309 | } | |
310 | ||
16380c15 | 311 | static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled) |
bf4994d7 SW |
312 | { |
313 | struct i2c_client *client = to_i2c_client(dev); | |
314 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
16380c15 | 315 | int ret; |
bf4994d7 SW |
316 | |
317 | mutex_lock(&ds1374->mutex); | |
318 | ||
16380c15 JS |
319 | ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); |
320 | if (ret < 0) | |
321 | goto out; | |
bf4994d7 | 322 | |
16380c15 | 323 | if (enabled) { |
bf4994d7 SW |
324 | ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; |
325 | ret &= ~DS1374_REG_CR_WDALM; | |
16380c15 JS |
326 | } else { |
327 | ret &= ~DS1374_REG_CR_WACE; | |
bf4994d7 | 328 | } |
16380c15 | 329 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); |
bf4994d7 SW |
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, | |
16380c15 | 341 | .alarm_irq_enable = ds1374_alarm_irq_enable, |
bf4994d7 SW |
342 | }; |
343 | ||
d2653e92 JD |
344 | static int ds1374_probe(struct i2c_client *client, |
345 | const struct i2c_device_id *id) | |
bf4994d7 SW |
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 | ||
b42f9317 | 364 | if (client->irq > 0) { |
bf4994d7 SW |
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 | } | |
26b3c01f AV |
371 | |
372 | device_set_wakeup_capable(&client->dev, 1); | |
bf4994d7 SW |
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: | |
b42f9317 | 386 | if (client->irq > 0) |
bf4994d7 SW |
387 | free_irq(client->irq, client); |
388 | ||
389 | out_free: | |
bf4994d7 SW |
390 | kfree(ds1374); |
391 | return ret; | |
392 | } | |
393 | ||
5a167f45 | 394 | static int ds1374_remove(struct i2c_client *client) |
bf4994d7 SW |
395 | { |
396 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
397 | ||
b42f9317 | 398 | if (client->irq > 0) { |
bf4994d7 SW |
399 | mutex_lock(&ds1374->mutex); |
400 | ds1374->exiting = 1; | |
401 | mutex_unlock(&ds1374->mutex); | |
402 | ||
403 | free_irq(client->irq, client); | |
9db8995b | 404 | cancel_work_sync(&ds1374->work); |
bf4994d7 SW |
405 | } |
406 | ||
407 | rtc_device_unregister(ds1374->rtc); | |
bf4994d7 SW |
408 | kfree(ds1374); |
409 | return 0; | |
410 | } | |
411 | ||
986e36a5 | 412 | #ifdef CONFIG_PM |
bc96ba74 | 413 | static int ds1374_suspend(struct device *dev) |
986e36a5 | 414 | { |
bc96ba74 MB |
415 | struct i2c_client *client = to_i2c_client(dev); |
416 | ||
986e36a5 MP |
417 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
418 | enable_irq_wake(client->irq); | |
419 | return 0; | |
420 | } | |
421 | ||
bc96ba74 | 422 | static int ds1374_resume(struct device *dev) |
986e36a5 | 423 | { |
bc96ba74 MB |
424 | struct i2c_client *client = to_i2c_client(dev); |
425 | ||
986e36a5 MP |
426 | if (client->irq >= 0 && device_may_wakeup(&client->dev)) |
427 | disable_irq_wake(client->irq); | |
428 | return 0; | |
429 | } | |
bc96ba74 MB |
430 | |
431 | static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume); | |
432 | ||
433 | #define DS1374_PM (&ds1374_pm) | |
986e36a5 | 434 | #else |
bc96ba74 | 435 | #define DS1374_PM NULL |
986e36a5 MP |
436 | #endif |
437 | ||
bf4994d7 SW |
438 | static struct i2c_driver ds1374_driver = { |
439 | .driver = { | |
440 | .name = "rtc-ds1374", | |
441 | .owner = THIS_MODULE, | |
bc96ba74 | 442 | .pm = DS1374_PM, |
bf4994d7 SW |
443 | }, |
444 | .probe = ds1374_probe, | |
5a167f45 | 445 | .remove = ds1374_remove, |
3760f736 | 446 | .id_table = ds1374_id, |
bf4994d7 SW |
447 | }; |
448 | ||
0abc9201 | 449 | module_i2c_driver(ds1374_driver); |
bf4994d7 SW |
450 | |
451 | MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); | |
452 | MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); | |
453 | MODULE_LICENSE("GPL"); |