]>
Commit | Line | Data |
---|---|---|
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> | |
27 | ||
28 | #define DS1374_REG_TOD0 0x00 /* Time of Day */ | |
29 | #define DS1374_REG_TOD1 0x01 | |
30 | #define DS1374_REG_TOD2 0x02 | |
31 | #define DS1374_REG_TOD3 0x03 | |
32 | #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */ | |
33 | #define DS1374_REG_WDALM1 0x05 | |
34 | #define DS1374_REG_WDALM2 0x06 | |
35 | #define DS1374_REG_CR 0x07 /* Control */ | |
36 | #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */ | |
37 | #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */ | |
38 | #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */ | |
39 | #define DS1374_REG_SR 0x08 /* Status */ | |
40 | #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */ | |
41 | #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */ | |
42 | #define DS1374_REG_TCR 0x09 /* Trickle Charge */ | |
43 | ||
44 | struct ds1374 { | |
45 | struct i2c_client *client; | |
46 | struct rtc_device *rtc; | |
47 | struct work_struct work; | |
48 | ||
49 | /* The mutex protects alarm operations, and prevents a race | |
50 | * between the enable_irq() in the workqueue and the free_irq() | |
51 | * in the remove function. | |
52 | */ | |
53 | struct mutex mutex; | |
54 | int exiting; | |
55 | }; | |
56 | ||
57 | static struct i2c_driver ds1374_driver; | |
58 | ||
59 | static int ds1374_read_rtc(struct i2c_client *client, u32 *time, | |
60 | int reg, int nbytes) | |
61 | { | |
62 | u8 buf[4]; | |
63 | int ret; | |
64 | int i; | |
65 | ||
66 | if (nbytes > 4) { | |
67 | WARN_ON(1); | |
68 | return -EINVAL; | |
69 | } | |
70 | ||
71 | ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf); | |
72 | ||
73 | if (ret < 0) | |
74 | return ret; | |
75 | if (ret < nbytes) | |
76 | return -EIO; | |
77 | ||
78 | for (i = nbytes - 1, *time = 0; i >= 0; i--) | |
79 | *time = (*time << 8) | buf[i]; | |
80 | ||
81 | return 0; | |
82 | } | |
83 | ||
84 | static int ds1374_write_rtc(struct i2c_client *client, u32 time, | |
85 | int reg, int nbytes) | |
86 | { | |
87 | u8 buf[4]; | |
88 | int i; | |
89 | ||
90 | if (nbytes > 4) { | |
91 | WARN_ON(1); | |
92 | return -EINVAL; | |
93 | } | |
94 | ||
95 | for (i = 0; i < nbytes; i++) { | |
96 | buf[i] = time & 0xff; | |
97 | time >>= 8; | |
98 | } | |
99 | ||
100 | return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf); | |
101 | } | |
102 | ||
103 | static int ds1374_check_rtc_status(struct i2c_client *client) | |
104 | { | |
105 | int ret = 0; | |
106 | int control, stat; | |
107 | ||
108 | stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); | |
109 | if (stat < 0) | |
110 | return stat; | |
111 | ||
112 | if (stat & DS1374_REG_SR_OSF) | |
113 | dev_warn(&client->dev, | |
114 | "oscillator discontinuity flagged, " | |
115 | "time unreliable\n"); | |
116 | ||
117 | stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF); | |
118 | ||
119 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); | |
120 | if (ret < 0) | |
121 | return ret; | |
122 | ||
123 | /* If the alarm is pending, clear it before requesting | |
124 | * the interrupt, so an interrupt event isn't reported | |
125 | * before everything is initialized. | |
126 | */ | |
127 | ||
128 | control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
129 | if (control < 0) | |
130 | return control; | |
131 | ||
132 | control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); | |
133 | return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); | |
134 | } | |
135 | ||
136 | static int ds1374_read_time(struct device *dev, struct rtc_time *time) | |
137 | { | |
138 | struct i2c_client *client = to_i2c_client(dev); | |
139 | u32 itime; | |
140 | int ret; | |
141 | ||
142 | ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4); | |
143 | if (!ret) | |
144 | rtc_time_to_tm(itime, time); | |
145 | ||
146 | return ret; | |
147 | } | |
148 | ||
149 | static int ds1374_set_time(struct device *dev, struct rtc_time *time) | |
150 | { | |
151 | struct i2c_client *client = to_i2c_client(dev); | |
152 | unsigned long itime; | |
153 | ||
154 | rtc_tm_to_time(time, &itime); | |
155 | return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4); | |
156 | } | |
157 | ||
158 | /* The ds1374 has a decrementer for an alarm, rather than a comparator. | |
159 | * If the time of day is changed, then the alarm will need to be | |
160 | * reset. | |
161 | */ | |
162 | static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm) | |
163 | { | |
164 | struct i2c_client *client = to_i2c_client(dev); | |
165 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
166 | u32 now, cur_alarm; | |
167 | int cr, sr; | |
168 | int ret = 0; | |
169 | ||
170 | if (client->irq < 0) | |
171 | return -EINVAL; | |
172 | ||
173 | mutex_lock(&ds1374->mutex); | |
174 | ||
175 | cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
176 | if (ret < 0) | |
177 | goto out; | |
178 | ||
179 | sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR); | |
180 | if (ret < 0) | |
181 | goto out; | |
182 | ||
183 | ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4); | |
184 | if (ret) | |
185 | goto out; | |
186 | ||
187 | ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3); | |
188 | if (ret) | |
189 | goto out; | |
190 | ||
191 | rtc_time_to_tm(now + cur_alarm, &alarm->time); | |
192 | alarm->enabled = !!(cr & DS1374_REG_CR_WACE); | |
193 | alarm->pending = !!(sr & DS1374_REG_SR_AF); | |
194 | ||
195 | out: | |
196 | mutex_unlock(&ds1374->mutex); | |
197 | return ret; | |
198 | } | |
199 | ||
200 | static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm) | |
201 | { | |
202 | struct i2c_client *client = to_i2c_client(dev); | |
203 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
204 | struct rtc_time now; | |
205 | unsigned long new_alarm, itime; | |
206 | int cr; | |
207 | int ret = 0; | |
208 | ||
209 | if (client->irq < 0) | |
210 | return -EINVAL; | |
211 | ||
212 | ret = ds1374_read_time(dev, &now); | |
213 | if (ret < 0) | |
214 | return ret; | |
215 | ||
216 | rtc_tm_to_time(&alarm->time, &new_alarm); | |
217 | rtc_tm_to_time(&now, &itime); | |
218 | ||
219 | new_alarm -= itime; | |
220 | ||
221 | /* This can happen due to races, in addition to dates that are | |
222 | * truly in the past. To avoid requiring the caller to check for | |
223 | * races, dates in the past are assumed to be in the recent past | |
224 | * (i.e. not something that we'd rather the caller know about via | |
225 | * an error), and the alarm is set to go off as soon as possible. | |
226 | */ | |
227 | if (new_alarm <= 0) | |
228 | new_alarm = 1; | |
229 | ||
230 | mutex_lock(&ds1374->mutex); | |
231 | ||
232 | ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
233 | if (ret < 0) | |
234 | goto out; | |
235 | ||
236 | /* Disable any existing alarm before setting the new one | |
237 | * (or lack thereof). */ | |
238 | cr &= ~DS1374_REG_CR_WACE; | |
239 | ||
240 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); | |
241 | if (ret < 0) | |
242 | goto out; | |
243 | ||
244 | ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3); | |
245 | if (ret) | |
246 | goto out; | |
247 | ||
248 | if (alarm->enabled) { | |
249 | cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; | |
250 | cr &= ~DS1374_REG_CR_WDALM; | |
251 | ||
252 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr); | |
253 | } | |
254 | ||
255 | out: | |
256 | mutex_unlock(&ds1374->mutex); | |
257 | return ret; | |
258 | } | |
259 | ||
260 | static irqreturn_t ds1374_irq(int irq, void *dev_id) | |
261 | { | |
262 | struct i2c_client *client = dev_id; | |
263 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
264 | ||
265 | disable_irq_nosync(irq); | |
266 | schedule_work(&ds1374->work); | |
267 | return IRQ_HANDLED; | |
268 | } | |
269 | ||
270 | static void ds1374_work(struct work_struct *work) | |
271 | { | |
272 | struct ds1374 *ds1374 = container_of(work, struct ds1374, work); | |
273 | struct i2c_client *client = ds1374->client; | |
274 | int stat, control; | |
275 | ||
276 | mutex_lock(&ds1374->mutex); | |
277 | ||
278 | stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR); | |
279 | if (stat < 0) | |
280 | return; | |
281 | ||
282 | if (stat & DS1374_REG_SR_AF) { | |
283 | stat &= ~DS1374_REG_SR_AF; | |
284 | i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat); | |
285 | ||
286 | control = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
287 | if (control < 0) | |
288 | goto out; | |
289 | ||
290 | control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE); | |
291 | i2c_smbus_write_byte_data(client, DS1374_REG_CR, control); | |
292 | ||
293 | /* rtc_update_irq() assumes that it is called | |
294 | * from IRQ-disabled context. | |
295 | */ | |
296 | local_irq_disable(); | |
297 | rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF); | |
298 | local_irq_enable(); | |
299 | } | |
300 | ||
301 | out: | |
302 | if (!ds1374->exiting) | |
303 | enable_irq(client->irq); | |
304 | ||
305 | mutex_unlock(&ds1374->mutex); | |
306 | } | |
307 | ||
308 | static int ds1374_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) | |
309 | { | |
310 | struct i2c_client *client = to_i2c_client(dev); | |
311 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
312 | int ret = -ENOIOCTLCMD; | |
313 | ||
314 | mutex_lock(&ds1374->mutex); | |
315 | ||
316 | switch (cmd) { | |
317 | case RTC_AIE_OFF: | |
318 | ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
319 | if (ret < 0) | |
320 | goto out; | |
321 | ||
322 | ret &= ~DS1374_REG_CR_WACE; | |
323 | ||
324 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); | |
325 | if (ret < 0) | |
326 | goto out; | |
327 | ||
328 | break; | |
329 | ||
330 | case RTC_AIE_ON: | |
331 | ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR); | |
332 | if (ret < 0) | |
333 | goto out; | |
334 | ||
335 | ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE; | |
336 | ret &= ~DS1374_REG_CR_WDALM; | |
337 | ||
338 | ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret); | |
339 | if (ret < 0) | |
340 | goto out; | |
341 | ||
342 | break; | |
343 | } | |
344 | ||
345 | out: | |
346 | mutex_unlock(&ds1374->mutex); | |
347 | return ret; | |
348 | } | |
349 | ||
350 | static const struct rtc_class_ops ds1374_rtc_ops = { | |
351 | .read_time = ds1374_read_time, | |
352 | .set_time = ds1374_set_time, | |
353 | .read_alarm = ds1374_read_alarm, | |
354 | .set_alarm = ds1374_set_alarm, | |
355 | .ioctl = ds1374_ioctl, | |
356 | }; | |
357 | ||
358 | static int ds1374_probe(struct i2c_client *client) | |
359 | { | |
360 | struct ds1374 *ds1374; | |
361 | int ret; | |
362 | ||
363 | ds1374 = kzalloc(sizeof(struct ds1374), GFP_KERNEL); | |
364 | if (!ds1374) | |
365 | return -ENOMEM; | |
366 | ||
367 | ds1374->client = client; | |
368 | i2c_set_clientdata(client, ds1374); | |
369 | ||
370 | INIT_WORK(&ds1374->work, ds1374_work); | |
371 | mutex_init(&ds1374->mutex); | |
372 | ||
373 | ret = ds1374_check_rtc_status(client); | |
374 | if (ret) | |
375 | goto out_free; | |
376 | ||
377 | if (client->irq >= 0) { | |
378 | ret = request_irq(client->irq, ds1374_irq, 0, | |
379 | "ds1374", client); | |
380 | if (ret) { | |
381 | dev_err(&client->dev, "unable to request IRQ\n"); | |
382 | goto out_free; | |
383 | } | |
384 | } | |
385 | ||
386 | ds1374->rtc = rtc_device_register(client->name, &client->dev, | |
387 | &ds1374_rtc_ops, THIS_MODULE); | |
388 | if (IS_ERR(ds1374->rtc)) { | |
389 | ret = PTR_ERR(ds1374->rtc); | |
390 | dev_err(&client->dev, "unable to register the class device\n"); | |
391 | goto out_irq; | |
392 | } | |
393 | ||
394 | return 0; | |
395 | ||
396 | out_irq: | |
397 | if (client->irq >= 0) | |
398 | free_irq(client->irq, client); | |
399 | ||
400 | out_free: | |
401 | i2c_set_clientdata(client, NULL); | |
402 | kfree(ds1374); | |
403 | return ret; | |
404 | } | |
405 | ||
406 | static int __devexit ds1374_remove(struct i2c_client *client) | |
407 | { | |
408 | struct ds1374 *ds1374 = i2c_get_clientdata(client); | |
409 | ||
410 | if (client->irq >= 0) { | |
411 | mutex_lock(&ds1374->mutex); | |
412 | ds1374->exiting = 1; | |
413 | mutex_unlock(&ds1374->mutex); | |
414 | ||
415 | free_irq(client->irq, client); | |
416 | flush_scheduled_work(); | |
417 | } | |
418 | ||
419 | rtc_device_unregister(ds1374->rtc); | |
420 | i2c_set_clientdata(client, NULL); | |
421 | kfree(ds1374); | |
422 | return 0; | |
423 | } | |
424 | ||
425 | static struct i2c_driver ds1374_driver = { | |
426 | .driver = { | |
427 | .name = "rtc-ds1374", | |
428 | .owner = THIS_MODULE, | |
429 | }, | |
430 | .probe = ds1374_probe, | |
431 | .remove = __devexit_p(ds1374_remove), | |
432 | }; | |
433 | ||
434 | static int __init ds1374_init(void) | |
435 | { | |
436 | return i2c_add_driver(&ds1374_driver); | |
437 | } | |
438 | ||
439 | static void __exit ds1374_exit(void) | |
440 | { | |
441 | i2c_del_driver(&ds1374_driver); | |
442 | } | |
443 | ||
444 | module_init(ds1374_init); | |
445 | module_exit(ds1374_exit); | |
446 | ||
447 | MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>"); | |
448 | MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver"); | |
449 | MODULE_LICENSE("GPL"); |