1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
4 *
5 * Based on code by Randy Vinson <rvinson@mvista.com>,
6 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
7 *
8 * Copyright (C) 2014 Rose Technology
9 * Copyright (C) 2006-2007 Freescale Semiconductor
10 * Copyright (c) 2005 MontaVista Software, Inc.
11 */
12 /*
13 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
14 * recommended in .../Documentation/i2c/writing-clients.rst section
15 * "Sending and receiving", using SMBus level communication is preferred.
16 */
17
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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 #ifdef CONFIG_RTC_DRV_DS1374_WDT
30 #include <linux/fs.h>
31 #include <linux/ioctl.h>
32 #include <linux/miscdevice.h>
33 #include <linux/reboot.h>
34 #include <linux/watchdog.h>
35 #endif
36
37 #define DS1374_REG_TOD0 0x00 /* Time of Day */
38 #define DS1374_REG_TOD1 0x01
39 #define DS1374_REG_TOD2 0x02
40 #define DS1374_REG_TOD3 0x03
41 #define DS1374_REG_WDALM0 0x04 /* Watchdog/Alarm */
42 #define DS1374_REG_WDALM1 0x05
43 #define DS1374_REG_WDALM2 0x06
44 #define DS1374_REG_CR 0x07 /* Control */
45 #define DS1374_REG_CR_AIE 0x01 /* Alarm Int. Enable */
46 #define DS1374_REG_CR_WDSTR 0x08 /* 1=INT, 0=RST */
47 #define DS1374_REG_CR_WDALM 0x20 /* 1=Watchdog, 0=Alarm */
48 #define DS1374_REG_CR_WACE 0x40 /* WD/Alarm counter enable */
49 #define DS1374_REG_SR 0x08 /* Status */
50 #define DS1374_REG_SR_OSF 0x80 /* Oscillator Stop Flag */
51 #define DS1374_REG_SR_AF 0x01 /* Alarm Flag */
52 #define DS1374_REG_TCR 0x09 /* Trickle Charge */
53
54 static const struct i2c_device_id ds1374_id[] = {
55 { "ds1374", 0 },
56 { }
57 };
58 MODULE_DEVICE_TABLE(i2c, ds1374_id);
59
60 #ifdef CONFIG_OF
61 static const struct of_device_id ds1374_of_match[] = {
62 { .compatible = "dallas,ds1374" },
63 { }
64 };
65 MODULE_DEVICE_TABLE(of, ds1374_of_match);
66 #endif
67
68 struct ds1374 {
69 struct i2c_client *client;
70 struct rtc_device *rtc;
71 struct work_struct work;
72 #ifdef CONFIG_RTC_DRV_DS1374_WDT
73 struct watchdog_device wdt;
74 #endif
75 /* The mutex protects alarm operations, and prevents a race
76 * between the enable_irq() in the workqueue and the free_irq()
77 * in the remove function.
78 */
79 struct mutex mutex;
80 int exiting;
81 };
82
83 static struct i2c_driver ds1374_driver;
84
ds1374_read_rtc(struct i2c_client * client,u32 * time,int reg,int nbytes)85 static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
86 int reg, int nbytes)
87 {
88 u8 buf[4];
89 int ret;
90 int i;
91
92 if (WARN_ON(nbytes > 4))
93 return -EINVAL;
94
95 ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);
96
97 if (ret < 0)
98 return ret;
99 if (ret < nbytes)
100 return -EIO;
101
102 for (i = nbytes - 1, *time = 0; i >= 0; i--)
103 *time = (*time << 8) | buf[i];
104
105 return 0;
106 }
107
ds1374_write_rtc(struct i2c_client * client,u32 time,int reg,int nbytes)108 static int ds1374_write_rtc(struct i2c_client *client, u32 time,
109 int reg, int nbytes)
110 {
111 u8 buf[4];
112 int i;
113
114 if (nbytes > 4) {
115 WARN_ON(1);
116 return -EINVAL;
117 }
118
119 for (i = 0; i < nbytes; i++) {
120 buf[i] = time & 0xff;
121 time >>= 8;
122 }
123
124 return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
125 }
126
ds1374_check_rtc_status(struct i2c_client * client)127 static int ds1374_check_rtc_status(struct i2c_client *client)
128 {
129 int ret = 0;
130 int control, stat;
131
132 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
133 if (stat < 0)
134 return stat;
135
136 if (stat & DS1374_REG_SR_OSF)
137 dev_warn(&client->dev,
138 "oscillator discontinuity flagged, time unreliable\n");
139
140 stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);
141
142 ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
143 if (ret < 0)
144 return ret;
145
146 /* If the alarm is pending, clear it before requesting
147 * the interrupt, so an interrupt event isn't reported
148 * before everything is initialized.
149 */
150
151 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
152 if (control < 0)
153 return control;
154
155 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
156 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
157 }
158
ds1374_read_time(struct device * dev,struct rtc_time * time)159 static int ds1374_read_time(struct device *dev, struct rtc_time *time)
160 {
161 struct i2c_client *client = to_i2c_client(dev);
162 u32 itime;
163 int ret;
164
165 ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
166 if (!ret)
167 rtc_time64_to_tm(itime, time);
168
169 return ret;
170 }
171
ds1374_set_time(struct device * dev,struct rtc_time * time)172 static int ds1374_set_time(struct device *dev, struct rtc_time *time)
173 {
174 struct i2c_client *client = to_i2c_client(dev);
175 unsigned long itime = rtc_tm_to_time64(time);
176
177 return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
178 }
179
180 #ifndef CONFIG_RTC_DRV_DS1374_WDT
181 /* The ds1374 has a decrementer for an alarm, rather than a comparator.
182 * If the time of day is changed, then the alarm will need to be
183 * reset.
184 */
ds1374_read_alarm(struct device * dev,struct rtc_wkalrm * alarm)185 static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
186 {
187 struct i2c_client *client = to_i2c_client(dev);
188 struct ds1374 *ds1374 = i2c_get_clientdata(client);
189 u32 now, cur_alarm;
190 int cr, sr;
191 int ret = 0;
192
193 if (client->irq <= 0)
194 return -EINVAL;
195
196 mutex_lock(&ds1374->mutex);
197
198 cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
199 if (ret < 0)
200 goto out;
201
202 sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
203 if (ret < 0)
204 goto out;
205
206 ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
207 if (ret)
208 goto out;
209
210 ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
211 if (ret)
212 goto out;
213
214 rtc_time64_to_tm(now + cur_alarm, &alarm->time);
215 alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
216 alarm->pending = !!(sr & DS1374_REG_SR_AF);
217
218 out:
219 mutex_unlock(&ds1374->mutex);
220 return ret;
221 }
222
ds1374_set_alarm(struct device * dev,struct rtc_wkalrm * alarm)223 static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
224 {
225 struct i2c_client *client = to_i2c_client(dev);
226 struct ds1374 *ds1374 = i2c_get_clientdata(client);
227 struct rtc_time now;
228 unsigned long new_alarm, itime;
229 int cr;
230 int ret = 0;
231
232 if (client->irq <= 0)
233 return -EINVAL;
234
235 ret = ds1374_read_time(dev, &now);
236 if (ret < 0)
237 return ret;
238
239 new_alarm = rtc_tm_to_time64(&alarm->time);
240 itime = rtc_tm_to_time64(&now);
241
242 /* This can happen due to races, in addition to dates that are
243 * truly in the past. To avoid requiring the caller to check for
244 * races, dates in the past are assumed to be in the recent past
245 * (i.e. not something that we'd rather the caller know about via
246 * an error), and the alarm is set to go off as soon as possible.
247 */
248 if (time_before_eq(new_alarm, itime))
249 new_alarm = 1;
250 else
251 new_alarm -= itime;
252
253 mutex_lock(&ds1374->mutex);
254
255 ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
256 if (ret < 0)
257 goto out;
258
259 /* Disable any existing alarm before setting the new one
260 * (or lack thereof). */
261 cr &= ~DS1374_REG_CR_WACE;
262
263 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
264 if (ret < 0)
265 goto out;
266
267 ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
268 if (ret)
269 goto out;
270
271 if (alarm->enabled) {
272 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
273 cr &= ~DS1374_REG_CR_WDALM;
274
275 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
276 }
277
278 out:
279 mutex_unlock(&ds1374->mutex);
280 return ret;
281 }
282 #endif
283
ds1374_irq(int irq,void * dev_id)284 static irqreturn_t ds1374_irq(int irq, void *dev_id)
285 {
286 struct i2c_client *client = dev_id;
287 struct ds1374 *ds1374 = i2c_get_clientdata(client);
288
289 disable_irq_nosync(irq);
290 schedule_work(&ds1374->work);
291 return IRQ_HANDLED;
292 }
293
ds1374_work(struct work_struct * work)294 static void ds1374_work(struct work_struct *work)
295 {
296 struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
297 struct i2c_client *client = ds1374->client;
298 int stat, control;
299
300 mutex_lock(&ds1374->mutex);
301
302 stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
303 if (stat < 0)
304 goto unlock;
305
306 if (stat & DS1374_REG_SR_AF) {
307 stat &= ~DS1374_REG_SR_AF;
308 i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
309
310 control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
311 if (control < 0)
312 goto out;
313
314 control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
315 i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
316
317 rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
318 }
319
320 out:
321 if (!ds1374->exiting)
322 enable_irq(client->irq);
323 unlock:
324 mutex_unlock(&ds1374->mutex);
325 }
326
327 #ifndef CONFIG_RTC_DRV_DS1374_WDT
ds1374_alarm_irq_enable(struct device * dev,unsigned int enabled)328 static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
329 {
330 struct i2c_client *client = to_i2c_client(dev);
331 struct ds1374 *ds1374 = i2c_get_clientdata(client);
332 int ret;
333
334 mutex_lock(&ds1374->mutex);
335
336 ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
337 if (ret < 0)
338 goto out;
339
340 if (enabled) {
341 ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
342 ret &= ~DS1374_REG_CR_WDALM;
343 } else {
344 ret &= ~DS1374_REG_CR_WACE;
345 }
346 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);
347
348 out:
349 mutex_unlock(&ds1374->mutex);
350 return ret;
351 }
352 #endif
353
354 static const struct rtc_class_ops ds1374_rtc_ops = {
355 .read_time = ds1374_read_time,
356 .set_time = ds1374_set_time,
357 #ifndef CONFIG_RTC_DRV_DS1374_WDT
358 .read_alarm = ds1374_read_alarm,
359 .set_alarm = ds1374_set_alarm,
360 .alarm_irq_enable = ds1374_alarm_irq_enable,
361 #endif
362 };
363
364 #ifdef CONFIG_RTC_DRV_DS1374_WDT
365 /*
366 *****************************************************************************
367 *
368 * Watchdog Driver
369 *
370 *****************************************************************************
371 */
372 /* Default margin */
373 #define TIMER_MARGIN_DEFAULT 32
374 #define TIMER_MARGIN_MIN 1
375 #define TIMER_MARGIN_MAX 4095 /* 24-bit value */
376
377 static int wdt_margin;
378 module_param(wdt_margin, int, 0);
379 MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");
380
381 static bool nowayout = WATCHDOG_NOWAYOUT;
382 module_param(nowayout, bool, 0);
383 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="
384 __MODULE_STRING(WATCHDOG_NOWAYOUT)")");
385
386 static const struct watchdog_info ds1374_wdt_info = {
387 .identity = "DS1374 Watchdog",
388 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
389 WDIOF_MAGICCLOSE,
390 };
391
ds1374_wdt_settimeout(struct watchdog_device * wdt,unsigned int timeout)392 static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
393 {
394 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
395 struct i2c_client *client = ds1374->client;
396 int ret, cr;
397
398 wdt->timeout = timeout;
399
400 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
401 if (cr < 0)
402 return cr;
403
404 /* Disable any existing watchdog/alarm before setting the new one */
405 cr &= ~DS1374_REG_CR_WACE;
406
407 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
408 if (ret < 0)
409 return ret;
410
411 /* Set new watchdog time */
412 timeout = timeout * 4096;
413 ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);
414 if (ret)
415 return ret;
416
417 /* Enable watchdog timer */
418 cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
419 cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
420 cr &= ~DS1374_REG_CR_AIE;
421
422 ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
423 if (ret < 0)
424 return ret;
425
426 return 0;
427 }
428
429 /*
430 * Reload the watchdog timer. (ie, pat the watchdog)
431 */
ds1374_wdt_start(struct watchdog_device * wdt)432 static int ds1374_wdt_start(struct watchdog_device *wdt)
433 {
434 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
435 u32 val;
436
437 return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);
438 }
439
ds1374_wdt_stop(struct watchdog_device * wdt)440 static int ds1374_wdt_stop(struct watchdog_device *wdt)
441 {
442 struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
443 struct i2c_client *client = ds1374->client;
444 int cr;
445
446 cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
447 if (cr < 0)
448 return cr;
449
450 /* Disable watchdog timer */
451 cr &= ~DS1374_REG_CR_WACE;
452
453 return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
454 }
455
456 static const struct watchdog_ops ds1374_wdt_ops = {
457 .owner = THIS_MODULE,
458 .start = ds1374_wdt_start,
459 .stop = ds1374_wdt_stop,
460 .set_timeout = ds1374_wdt_settimeout,
461 };
462 #endif /*CONFIG_RTC_DRV_DS1374_WDT*/
463 /*
464 *****************************************************************************
465 *
466 * Driver Interface
467 *
468 *****************************************************************************
469 */
ds1374_probe(struct i2c_client * client)470 static int ds1374_probe(struct i2c_client *client)
471 {
472 struct ds1374 *ds1374;
473 int ret;
474
475 ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
476 if (!ds1374)
477 return -ENOMEM;
478
479 ds1374->rtc = devm_rtc_allocate_device(&client->dev);
480 if (IS_ERR(ds1374->rtc))
481 return PTR_ERR(ds1374->rtc);
482
483 ds1374->client = client;
484 i2c_set_clientdata(client, ds1374);
485
486 INIT_WORK(&ds1374->work, ds1374_work);
487 mutex_init(&ds1374->mutex);
488
489 ret = ds1374_check_rtc_status(client);
490 if (ret)
491 return ret;
492
493 if (client->irq > 0) {
494 ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
495 "ds1374", client);
496 if (ret) {
497 dev_err(&client->dev, "unable to request IRQ\n");
498 return ret;
499 }
500
501 device_set_wakeup_capable(&client->dev, 1);
502 }
503
504 ds1374->rtc->ops = &ds1374_rtc_ops;
505 ds1374->rtc->range_max = U32_MAX;
506
507 ret = devm_rtc_register_device(ds1374->rtc);
508 if (ret)
509 return ret;
510
511 #ifdef CONFIG_RTC_DRV_DS1374_WDT
512 ds1374->wdt.info = &ds1374_wdt_info;
513 ds1374->wdt.ops = &ds1374_wdt_ops;
514 ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
515 ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
516 ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;
517
518 watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);
519 watchdog_set_nowayout(&ds1374->wdt, nowayout);
520 watchdog_stop_on_reboot(&ds1374->wdt);
521 watchdog_stop_on_unregister(&ds1374->wdt);
522 watchdog_set_drvdata(&ds1374->wdt, ds1374);
523 ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);
524
525 ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
526 if (ret)
527 return ret;
528 #endif
529
530 return 0;
531 }
532
ds1374_remove(struct i2c_client * client)533 static void ds1374_remove(struct i2c_client *client)
534 {
535 struct ds1374 *ds1374 = i2c_get_clientdata(client);
536
537 if (client->irq > 0) {
538 mutex_lock(&ds1374->mutex);
539 ds1374->exiting = 1;
540 mutex_unlock(&ds1374->mutex);
541
542 devm_free_irq(&client->dev, client->irq, client);
543 cancel_work_sync(&ds1374->work);
544 }
545 }
546
547 #ifdef CONFIG_PM_SLEEP
ds1374_suspend(struct device * dev)548 static int ds1374_suspend(struct device *dev)
549 {
550 struct i2c_client *client = to_i2c_client(dev);
551
552 if (client->irq > 0 && device_may_wakeup(&client->dev))
553 enable_irq_wake(client->irq);
554 return 0;
555 }
556
ds1374_resume(struct device * dev)557 static int ds1374_resume(struct device *dev)
558 {
559 struct i2c_client *client = to_i2c_client(dev);
560
561 if (client->irq > 0 && device_may_wakeup(&client->dev))
562 disable_irq_wake(client->irq);
563 return 0;
564 }
565 #endif
566
567 static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);
568
569 static struct i2c_driver ds1374_driver = {
570 .driver = {
571 .name = "rtc-ds1374",
572 .of_match_table = of_match_ptr(ds1374_of_match),
573 .pm = &ds1374_pm,
574 },
575 .probe_new = ds1374_probe,
576 .remove = ds1374_remove,
577 .id_table = ds1374_id,
578 };
579
580 module_i2c_driver(ds1374_driver);
581
582 MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
583 MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
584 MODULE_LICENSE("GPL");
585