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) 2014 Rose Technology
8 * Copyright (C) 2006-2007 Freescale Semiconductor
9 *
10 * 2005 (c) MontaVista Software, Inc. This file is licensed under
11 * the terms of the GNU General Public License version 2. This program
12 * is licensed "as is" without any warranty of any kind, whether express
13 * or implied.
14 */
15 /*
16 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
17 * recommended in .../Documentation/i2c/writing-clients.rst section
18 * "Sending and receiving", using SMBus level communication is preferred.
19 */
20
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/interrupt.h>
26 #include <linux/i2c.h>
27 #include <linux/rtc.h>
28 #include <linux/bcd.h>
29 #include <linux/workqueue.h>
30 #include <linux/slab.h>
31 #include <linux/pm.h>
32 #ifdef CONFIG_RTC_DRV_DS1374_WDT
33 #include <linux/fs.h>
34 #include <linux/ioctl.h>
35 #include <linux/miscdevice.h>
36 #include <linux/reboot.h>
37 #include <linux/watchdog.h>
38 #endif
39
40 #define DS1374_REG_TOD0 0x00 /* Time of Day */
41 #define DS1374_REG_TOD1 0x01
42 #define DS1374_REG_TOD2 0x02
43 #define DS1374_REG_TOD3 0x03
44 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */
45 #define DS1374_REG_WDALM1 0x05
46 #define DS1374_REG_WDALM2 0x06
47 #define DS1374_REG_CR 0x07 /* Control */
48 #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */
49 #define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */
50 #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */
51 #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */
52 #define DS1374_REG_SR 0x08 /* Status */
53 #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */
54 #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */
55 #define DS1374_REG_TCR 0x09 /* Trickle Charge */
56
57 static const struct i2c_device_id ds1374_id[] = {
58 { "ds1374", 0 },
59 { }
60 };
61 MODULE_DEVICE_TABLE(i2c, ds1374_id);
62
63 #ifdef CONFIG_OF
64 static const struct of_device_id ds1374_of_match[] = {
65 { .compatible = "dallas,ds1374" },
66 { }
67 };
68 MODULE_DEVICE_TABLE(of, ds1374_of_match);
69 #endif
70
71 struct ds1374 {
72 struct i2c_client *client;
73 struct rtc_device *rtc;
74 struct work_struct work;
75 #ifdef CONFIG_RTC_DRV_DS1374_WDT
76 struct watchdog_device wdt;
77 #endif
78 /* The mutex protects alarm operations, and prevents a race
79 * between the enable_irq() in the workqueue and the free_irq()
80 * in the remove function.
81 */
82 struct mutex mutex;
83 int exiting;
84 };
85
86 static struct i2c_driver ds1374_driver;
87
ds1374_read_rtc(struct i2c_client * client,u32 * time,int reg,int nbytes)88 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
89 int reg, int nbytes)
90 {
91 u8 buf[4];
92 int ret;
93 int i;
94
95 if (WARN_ON(nbytes > 4))
96 return -EINVAL;
97
98 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
99
100 if (ret < 0)
101 return ret;
102 if (ret < nbytes)
103 return -EIO;
104
105 for (i = nbytes - 1, *time = 0; i >= 0; i--)
106 *time = (*time << 8) | buf[i];
107
108 return 0;
109 }
110
ds1374_write_rtc(struct i2c_client * client,u32 time,int reg,int nbytes)111 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
112 int reg, int nbytes)
113 {
114 u8 buf[4];
115 int i;
116
117 if (nbytes > 4) {
118 WARN_ON(1);
119 return -EINVAL;
120 }
121
122 for (i = 0; i < nbytes; i++) {
123 buf[i] = time & 0xff;
124 time >>= 8;
125 }
126
127 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
128 }
129
ds1374_check_rtc_status(struct i2c_client * client)130 static int ds1374_check_rtc_status(struct i2c_client *client)
131 {
132 int ret = 0;
133 int control, stat;
134
135 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
136 if (stat < 0)
137 return stat;
138
139 if (stat & DS1374_REG_SR_OSF)
140 dev_warn(&client->dev,
141 "oscillator discontinuity flagged, time unreliable\n");
142
143 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
144
145 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
146 if (ret < 0)
147 return ret;
148
149 /* If the alarm is pending, clear it before requesting
150 * the interrupt, so an interrupt event isn't reported
151 * before everything is initialized.
152 */
153
154 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
155 if (control < 0)
156 return control;
157
158 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
159 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
160 }
161
ds1374_read_time(struct device * dev,struct rtc_time * time)162 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
163 {
164 struct i2c_client *client = to_i2c_client(dev);
165 u32 itime;
166 int ret;
167
168 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
169 if (!ret)
170 rtc_time64_to_tm(itime, time);
171
172 return ret;
173 }
174
ds1374_set_time(struct device * dev,struct rtc_time * time)175 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
176 {
177 struct i2c_client *client = to_i2c_client(dev);
178 unsigned long itime = rtc_tm_to_time64(time);
179
180 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
181 }
182
183 #ifndef CONFIG_RTC_DRV_DS1374_WDT
184 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
185 * If the time of day is changed, then the alarm will need to be
186 * reset.
187 */
ds1374_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)188 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
189 {
190 struct i2c_client *client = to_i2c_client(dev);
191 struct ds1374 *ds1374 = i2c_get_clientdata(client);
192 u32 now, cur_alarm;
193 int cr, sr;
194 int ret = 0;
195
196 if (client->irq <= 0)
197 return -EINVAL;
198
199 mutex_lock(&ds1374->mutex);
200
201 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
202 if (ret < 0)
203 goto out;
204
205 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
206 if (ret < 0)
207 goto out;
208
209 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
210 if (ret)
211 goto out;
212
213 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
214 if (ret)
215 goto out;
216
217 rtc_time64_to_tm(now + cur_alarm, &alarm->time);
218 alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
219 alarm->pending = !!(sr & DS1374_REG_SR_AF);
220
221 out:
222 mutex_unlock(&ds1374->mutex);
223 return ret;
224 }
225
ds1374_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)226 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
227 {
228 struct i2c_client *client = to_i2c_client(dev);
229 struct ds1374 *ds1374 = i2c_get_clientdata(client);
230 struct rtc_time now;
231 unsigned long new_alarm, itime;
232 int cr;
233 int ret = 0;
234
235 if (client->irq <= 0)
236 return -EINVAL;
237
238 ret = ds1374_read_time(dev, &now);
239 if (ret < 0)
240 return ret;
241
242 new_alarm = rtc_tm_to_time64(&alarm->time);
243 itime = rtc_tm_to_time64(&now);
244
245 /* This can happen due to races, in addition to dates that are
246 * truly in the past. To avoid requiring the caller to check for
247 * races, dates in the past are assumed to be in the recent past
248 * (i.e. not something that we'd rather the caller know about via
249 * an error), and the alarm is set to go off as soon as possible.
250 */
251 if (time_before_eq(new_alarm, itime))
252 new_alarm = 1;
253 else
254 new_alarm -= itime;
255
256 mutex_lock(&ds1374->mutex);
257
258 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
259 if (ret < 0)
260 goto out;
261
262 /* Disable any existing alarm before setting the new one
263 * (or lack thereof). */
264 cr &= ~DS1374_REG_CR_WACE;
265
266 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
267 if (ret < 0)
268 goto out;
269
270 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
271 if (ret)
272 goto out;
273
274 if (alarm->enabled) {
275 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
276 cr &= ~DS1374_REG_CR_WDALM;
277
278 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
279 }
280
281 out:
282 mutex_unlock(&ds1374->mutex);
283 return ret;
284 }
285 #endif
286
ds1374_irq(int irq,void * dev_id)287 static irqreturn_t ds1374_irq(int irq, void *dev_id)
288 {
289 struct i2c_client *client = dev_id;
290 struct ds1374 *ds1374 = i2c_get_clientdata(client);
291
292 disable_irq_nosync(irq);
293 schedule_work(&ds1374->work);
294 return IRQ_HANDLED;
295 }
296
ds1374_work(struct work_struct * work)297 static void ds1374_work(struct work_struct *work)
298 {
299 struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
300 struct i2c_client *client = ds1374->client;
301 int stat, control;
302
303 mutex_lock(&ds1374->mutex);
304
305 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
306 if (stat < 0)
307 goto unlock;
308
309 if (stat & DS1374_REG_SR_AF) {
310 stat &= ~DS1374_REG_SR_AF;
311 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
312
313 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
314 if (control < 0)
315 goto out;
316
317 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
318 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
319
320 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
321 }
322
323 out:
324 if (!ds1374->exiting)
325 enable_irq(client->irq);
326 unlock:
327 mutex_unlock(&ds1374->mutex);
328 }
329
330 #ifndef CONFIG_RTC_DRV_DS1374_WDT
ds1374_alarm_irq_enable(struct device * dev,unsigned int enabled)331 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
332 {
333 struct i2c_client *client = to_i2c_client(dev);
334 struct ds1374 *ds1374 = i2c_get_clientdata(client);
335 int ret;
336
337 mutex_lock(&ds1374->mutex);
338
339 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
340 if (ret < 0)
341 goto out;
342
343 if (enabled) {
344 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
345 ret &= ~DS1374_REG_CR_WDALM;
346 } else {
347 ret &= ~DS1374_REG_CR_WACE;
348 }
349 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
350
351 out:
352 mutex_unlock(&ds1374->mutex);
353 return ret;
354 }
355 #endif
356
357 static const struct rtc_class_ops ds1374_rtc_ops = {
358 .read_time = ds1374_read_time,
359 .set_time = ds1374_set_time,
360 #ifndef CONFIG_RTC_DRV_DS1374_WDT
361 .read_alarm = ds1374_read_alarm,
362 .set_alarm = ds1374_set_alarm,
363 .alarm_irq_enable = ds1374_alarm_irq_enable,
364 #endif
365 };
366
367 #ifdef CONFIG_RTC_DRV_DS1374_WDT
368 /*
369 *****************************************************************************
370 *
371 * Watchdog Driver
372 *
373 *****************************************************************************
374 */
375 /* Default margin */
376 #define TIMER_MARGIN_DEFAULT 32
377 #define TIMER_MARGIN_MIN 1
378 #define TIMER_MARGIN_MAX 4095 /* 24-bit value */
379
380 static int wdt_margin;
381 module_param(wdt_margin, int, 0);
382 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
383
384 static bool nowayout = WATCHDOG_NOWAYOUT;
385 module_param(nowayout, bool, 0);
386 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="
387 __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
388
389 static const struct watchdog_info ds1374_wdt_info = {
390 .identity = "DS1374 Watchdog",
391 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
392 WDIOF_MAGICCLOSE,
393 };
394
ds1374_wdt_settimeout(struct watchdog_device * wdt,unsigned int timeout)395 static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
396 {
397 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
398 struct i2c_client *client = ds1374->client;
399 int ret, cr;
400
401 wdt->timeout = timeout;
402
403 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
404 if (cr < 0)
405 return cr;
406
407 /* Disable any existing watchdog/alarm before setting the new one */
408 cr &= ~DS1374_REG_CR_WACE;
409
410 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
411 if (ret < 0)
412 return ret;
413
414 /* Set new watchdog time */
415 timeout = timeout * 4096;
416 ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);
417 if (ret)
418 return ret;
419
420 /* Enable watchdog timer */
421 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
422 cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
423 cr &= ~DS1374_REG_CR_AIE;
424
425 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
426 if (ret < 0)
427 return ret;
428
429 return 0;
430 }
431
432 /*
433 * Reload the watchdog timer. (ie, pat the watchdog)
434 */
ds1374_wdt_start(struct watchdog_device * wdt)435 static int ds1374_wdt_start(struct watchdog_device *wdt)
436 {
437 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
438 u32 val;
439
440 return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);
441 }
442
ds1374_wdt_stop(struct watchdog_device * wdt)443 static int ds1374_wdt_stop(struct watchdog_device *wdt)
444 {
445 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
446 struct i2c_client *client = ds1374->client;
447 int cr;
448
449 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
450 if (cr < 0)
451 return cr;
452
453 /* Disable watchdog timer */
454 cr &= ~DS1374_REG_CR_WACE;
455
456 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
457 }
458
459 static const struct watchdog_ops ds1374_wdt_ops = {
460 .owner = THIS_MODULE,
461 .start = ds1374_wdt_start,
462 .stop = ds1374_wdt_stop,
463 .set_timeout = ds1374_wdt_settimeout,
464 };
465 #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
466 /*
467 *****************************************************************************
468 *
469 * Driver Interface
470 *
471 *****************************************************************************
472 */
ds1374_probe(struct i2c_client * client,const struct i2c_device_id * id)473 static int ds1374_probe(struct i2c_client *client,
474 const struct i2c_device_id *id)
475 {
476 struct ds1374 *ds1374;
477 int ret;
478
479 ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
480 if (!ds1374)
481 return -ENOMEM;
482
483 ds1374->rtc = devm_rtc_allocate_device(&client->dev);
484 if (IS_ERR(ds1374->rtc))
485 return PTR_ERR(ds1374->rtc);
486
487 ds1374->client = client;
488 i2c_set_clientdata(client, ds1374);
489
490 INIT_WORK(&ds1374->work, ds1374_work);
491 mutex_init(&ds1374->mutex);
492
493 ret = ds1374_check_rtc_status(client);
494 if (ret)
495 return ret;
496
497 if (client->irq > 0) {
498 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
499 "ds1374", client);
500 if (ret) {
501 dev_err(&client->dev, "unable to request IRQ\n");
502 return ret;
503 }
504
505 device_set_wakeup_capable(&client->dev, 1);
506 }
507
508 ds1374->rtc->ops = &ds1374_rtc_ops;
509 ds1374->rtc->range_max = U32_MAX;
510
511 ret = rtc_register_device(ds1374->rtc);
512 if (ret)
513 return ret;
514
515 #ifdef CONFIG_RTC_DRV_DS1374_WDT
516 ds1374->wdt.info = &ds1374_wdt_info;
517 ds1374->wdt.ops = &ds1374_wdt_ops;
518 ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
519 ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
520 ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
521
522 watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);
523 watchdog_set_nowayout(&ds1374->wdt, nowayout);
524 watchdog_stop_on_reboot(&ds1374->wdt);
525 watchdog_stop_on_unregister(&ds1374->wdt);
526 watchdog_set_drvdata(&ds1374->wdt, ds1374);
527 ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);
528
529 ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
530 if (ret)
531 return ret;
532 #endif
533
534 return 0;
535 }
536
ds1374_remove(struct i2c_client * client)537 static int ds1374_remove(struct i2c_client *client)
538 {
539 struct ds1374 *ds1374 = i2c_get_clientdata(client);
540
541 if (client->irq > 0) {
542 mutex_lock(&ds1374->mutex);
543 ds1374->exiting = 1;
544 mutex_unlock(&ds1374->mutex);
545
546 devm_free_irq(&client->dev, client->irq, client);
547 cancel_work_sync(&ds1374->work);
548 }
549
550 return 0;
551 }
552
553 #ifdef CONFIG_PM_SLEEP
ds1374_suspend(struct device * dev)554 static int ds1374_suspend(struct device *dev)
555 {
556 struct i2c_client *client = to_i2c_client(dev);
557
558 if (client->irq > 0 && device_may_wakeup(&client->dev))
559 enable_irq_wake(client->irq);
560 return 0;
561 }
562
ds1374_resume(struct device * dev)563 static int ds1374_resume(struct device *dev)
564 {
565 struct i2c_client *client = to_i2c_client(dev);
566
567 if (client->irq > 0 && device_may_wakeup(&client->dev))
568 disable_irq_wake(client->irq);
569 return 0;
570 }
571 #endif
572
573 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
574
575 static struct i2c_driver ds1374_driver = {
576 .driver = {
577 .name = "rtc-ds1374",
578 .of_match_table = of_match_ptr(ds1374_of_match),
579 .pm = &ds1374_pm,
580 },
581 .probe = ds1374_probe,
582 .remove = ds1374_remove,
583 .id_table = ds1374_id,
584 };
585
586 module_i2c_driver(ds1374_driver);
587
588 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
589 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
590 MODULE_LICENSE("GPL");
591