summaryrefslogtreecommitdiff
path: root/drivers/rtc/rtc-ds1374.c
blob: 4a5005cb23f5930139b91c20b7cb5ca904b01dd5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
// SPDX-License-Identifier: GPL-2.0-only
/*
 * RTC client/driver for the Maxim/Dallas DS1374 Real-Time Clock over I2C
 *
 * Based on code by Randy Vinson <rvinson@mvista.com>,
 * which was based on the m41t00.c by Mark Greer <mgreer@mvista.com>.
 *
 * Copyright (C) 2014 Rose Technology
 * Copyright (C) 2006-2007 Freescale Semiconductor
 * Copyright (c) 2005 MontaVista Software, Inc.
 */
/*
 * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
 * recommended in .../Documentation/i2c/writing-clients.rst section
 * "Sending and receiving", using SMBus level communication is preferred.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/pm.h>
#ifdef CONFIG_RTC_DRV_DS1374_WDT
#include <linux/fs.h>
#include <linux/ioctl.h>
#include <linux/miscdevice.h>
#include <linux/reboot.h>
#include <linux/watchdog.h>
#endif

#define DS1374_REG_TOD0		0x00 /* Time of Day */
#define DS1374_REG_TOD1		0x01
#define DS1374_REG_TOD2		0x02
#define DS1374_REG_TOD3		0x03
#define DS1374_REG_WDALM0	0x04 /* Watchdog/Alarm */
#define DS1374_REG_WDALM1	0x05
#define DS1374_REG_WDALM2	0x06
#define DS1374_REG_CR		0x07 /* Control */
#define DS1374_REG_CR_AIE	0x01 /* Alarm Int. Enable */
#define DS1374_REG_CR_WDSTR	0x08 /* 1=INT, 0=RST */
#define DS1374_REG_CR_WDALM	0x20 /* 1=Watchdog, 0=Alarm */
#define DS1374_REG_CR_WACE	0x40 /* WD/Alarm counter enable */
#define DS1374_REG_SR		0x08 /* Status */
#define DS1374_REG_SR_OSF	0x80 /* Oscillator Stop Flag */
#define DS1374_REG_SR_AF	0x01 /* Alarm Flag */
#define DS1374_REG_TCR		0x09 /* Trickle Charge */

static const struct i2c_device_id ds1374_id[] = {
	{ "ds1374", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ds1374_id);

#ifdef CONFIG_OF
static const struct of_device_id ds1374_of_match[] = {
	{ .compatible = "dallas,ds1374" },
	{ }
};
MODULE_DEVICE_TABLE(of, ds1374_of_match);
#endif

struct ds1374 {
	struct i2c_client *client;
	struct rtc_device *rtc;
	struct work_struct work;
#ifdef CONFIG_RTC_DRV_DS1374_WDT
	struct watchdog_device wdt;
#endif
	/* The mutex protects alarm operations, and prevents a race
	 * between the enable_irq() in the workqueue and the free_irq()
	 * in the remove function.
	 */
	struct mutex mutex;
	int exiting;
};

static struct i2c_driver ds1374_driver;

static int ds1374_read_rtc(struct i2c_client *client, u32 *time,
			   int reg, int nbytes)
{
	u8 buf[4];
	int ret;
	int i;

	if (WARN_ON(nbytes > 4))
		return -EINVAL;

	ret = i2c_smbus_read_i2c_block_data(client, reg, nbytes, buf);

	if (ret < 0)
		return ret;
	if (ret < nbytes)
		return -EIO;

	for (i = nbytes - 1, *time = 0; i >= 0; i--)
		*time = (*time << 8) | buf[i];

	return 0;
}

static int ds1374_write_rtc(struct i2c_client *client, u32 time,
			    int reg, int nbytes)
{
	u8 buf[4];
	int i;

	if (nbytes > 4) {
		WARN_ON(1);
		return -EINVAL;
	}

	for (i = 0; i < nbytes; i++) {
		buf[i] = time & 0xff;
		time >>= 8;
	}

	return i2c_smbus_write_i2c_block_data(client, reg, nbytes, buf);
}

static int ds1374_check_rtc_status(struct i2c_client *client)
{
	int ret = 0;
	int control, stat;

	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (stat < 0)
		return stat;

	if (stat & DS1374_REG_SR_OSF)
		dev_warn(&client->dev,
			 "oscillator discontinuity flagged, time unreliable\n");

	stat &= ~(DS1374_REG_SR_OSF | DS1374_REG_SR_AF);

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);
	if (ret < 0)
		return ret;

	/* If the alarm is pending, clear it before requesting
	 * the interrupt, so an interrupt event isn't reported
	 * before everything is initialized.
	 */

	control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (control < 0)
		return control;

	control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);
}

static int ds1374_read_time(struct device *dev, struct rtc_time *time)
{
	struct i2c_client *client = to_i2c_client(dev);
	u32 itime;
	int ret;

	ret = ds1374_read_rtc(client, &itime, DS1374_REG_TOD0, 4);
	if (!ret)
		rtc_time64_to_tm(itime, time);

	return ret;
}

static int ds1374_set_time(struct device *dev, struct rtc_time *time)
{
	struct i2c_client *client = to_i2c_client(dev);
	unsigned long itime = rtc_tm_to_time64(time);

	return ds1374_write_rtc(client, itime, DS1374_REG_TOD0, 4);
}

#ifndef CONFIG_RTC_DRV_DS1374_WDT
/* The ds1374 has a decrementer for an alarm, rather than a comparator.
 * If the time of day is changed, then the alarm will need to be
 * reset.
 */
static int ds1374_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	u32 now, cur_alarm;
	int cr, sr;
	int ret = 0;

	if (client->irq <= 0)
		return -EINVAL;

	mutex_lock(&ds1374->mutex);

	cr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
		goto out;

	sr = ret = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (ret < 0)
		goto out;

	ret = ds1374_read_rtc(client, &now, DS1374_REG_TOD0, 4);
	if (ret)
		goto out;

	ret = ds1374_read_rtc(client, &cur_alarm, DS1374_REG_WDALM0, 3);
	if (ret)
		goto out;

	rtc_time64_to_tm(now + cur_alarm, &alarm->time);
	alarm->enabled = !!(cr & DS1374_REG_CR_WACE);
	alarm->pending = !!(sr & DS1374_REG_SR_AF);

out:
	mutex_unlock(&ds1374->mutex);
	return ret;
}

static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	struct rtc_time now;
	unsigned long new_alarm, itime;
	int cr;
	int ret = 0;

	if (client->irq <= 0)
		return -EINVAL;

	ret = ds1374_read_time(dev, &now);
	if (ret < 0)
		return ret;

	new_alarm = rtc_tm_to_time64(&alarm->time);
	itime = rtc_tm_to_time64(&now);

	/* This can happen due to races, in addition to dates that are
	 * truly in the past.  To avoid requiring the caller to check for
	 * races, dates in the past are assumed to be in the recent past
	 * (i.e. not something that we'd rather the caller know about via
	 * an error), and the alarm is set to go off as soon as possible.
	 */
	if (time_before_eq(new_alarm, itime))
		new_alarm = 1;
	else
		new_alarm -= itime;

	mutex_lock(&ds1374->mutex);

	ret = cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
		goto out;

	/* Disable any existing alarm before setting the new one
	 * (or lack thereof). */
	cr &= ~DS1374_REG_CR_WACE;

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	if (ret < 0)
		goto out;

	ret = ds1374_write_rtc(client, new_alarm, DS1374_REG_WDALM0, 3);
	if (ret)
		goto out;

	if (alarm->enabled) {
		cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
		cr &= ~DS1374_REG_CR_WDALM;

		ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	}

out:
	mutex_unlock(&ds1374->mutex);
	return ret;
}
#endif

static irqreturn_t ds1374_irq(int irq, void *dev_id)
{
	struct i2c_client *client = dev_id;
	struct ds1374 *ds1374 = i2c_get_clientdata(client);

	disable_irq_nosync(irq);
	schedule_work(&ds1374->work);
	return IRQ_HANDLED;
}

static void ds1374_work(struct work_struct *work)
{
	struct ds1374 *ds1374 = container_of(work, struct ds1374, work);
	struct i2c_client *client = ds1374->client;
	int stat, control;

	mutex_lock(&ds1374->mutex);

	stat = i2c_smbus_read_byte_data(client, DS1374_REG_SR);
	if (stat < 0)
		goto unlock;

	if (stat & DS1374_REG_SR_AF) {
		stat &= ~DS1374_REG_SR_AF;
		i2c_smbus_write_byte_data(client, DS1374_REG_SR, stat);

		control = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
		if (control < 0)
			goto out;

		control &= ~(DS1374_REG_CR_WACE | DS1374_REG_CR_AIE);
		i2c_smbus_write_byte_data(client, DS1374_REG_CR, control);

		rtc_update_irq(ds1374->rtc, 1, RTC_AF | RTC_IRQF);
	}

out:
	if (!ds1374->exiting)
		enable_irq(client->irq);
unlock:
	mutex_unlock(&ds1374->mutex);
}

#ifndef CONFIG_RTC_DRV_DS1374_WDT
static int ds1374_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ds1374 *ds1374 = i2c_get_clientdata(client);
	int ret;

	mutex_lock(&ds1374->mutex);

	ret = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (ret < 0)
		goto out;

	if (enabled) {
		ret |= DS1374_REG_CR_WACE | DS1374_REG_CR_AIE;
		ret &= ~DS1374_REG_CR_WDALM;
	} else {
		ret &= ~DS1374_REG_CR_WACE;
	}
	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, ret);

out:
	mutex_unlock(&ds1374->mutex);
	return ret;
}
#endif

static const struct rtc_class_ops ds1374_rtc_ops = {
	.read_time = ds1374_read_time,
	.set_time = ds1374_set_time,
#ifndef CONFIG_RTC_DRV_DS1374_WDT
	.read_alarm = ds1374_read_alarm,
	.set_alarm = ds1374_set_alarm,
	.alarm_irq_enable = ds1374_alarm_irq_enable,
#endif
};

#ifdef CONFIG_RTC_DRV_DS1374_WDT
/*
 *****************************************************************************
 *
 * Watchdog Driver
 *
 *****************************************************************************
 */
/* Default margin */
#define TIMER_MARGIN_DEFAULT	32
#define TIMER_MARGIN_MIN	1
#define TIMER_MARGIN_MAX	4095 /* 24-bit value */

static int wdt_margin;
module_param(wdt_margin, int, 0);
MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 32s)");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default ="
		__MODULE_STRING(WATCHDOG_NOWAYOUT)")");

static const struct watchdog_info ds1374_wdt_info = {
	.identity       = "DS1374 Watchdog",
	.options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
						WDIOF_MAGICCLOSE,
};

static int ds1374_wdt_settimeout(struct watchdog_device *wdt, unsigned int timeout)
{
	struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
	struct i2c_client *client = ds1374->client;
	int ret, cr;

	wdt->timeout = timeout;

	cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (cr < 0)
		return cr;

	/* Disable any existing watchdog/alarm before setting the new one */
	cr &= ~DS1374_REG_CR_WACE;

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	if (ret < 0)
		return ret;

	/* Set new watchdog time */
	timeout = timeout * 4096;
	ret = ds1374_write_rtc(client, timeout, DS1374_REG_WDALM0, 3);
	if (ret)
		return ret;

	/* Enable watchdog timer */
	cr |= DS1374_REG_CR_WACE | DS1374_REG_CR_WDALM;
	cr &= ~DS1374_REG_CR_WDSTR;/* for RST PIN */
	cr &= ~DS1374_REG_CR_AIE;

	ret = i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
	if (ret < 0)
		return ret;

	return 0;
}

/*
 * Reload the watchdog timer.  (ie, pat the watchdog)
 */
static int ds1374_wdt_start(struct watchdog_device *wdt)
{
	struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
	u32 val;

	return ds1374_read_rtc(ds1374->client, &val, DS1374_REG_WDALM0, 3);
}

static int ds1374_wdt_stop(struct watchdog_device *wdt)
{
	struct ds1374 *ds1374 = watchdog_get_drvdata(wdt);
	struct i2c_client *client = ds1374->client;
	int cr;

	cr = i2c_smbus_read_byte_data(client, DS1374_REG_CR);
	if (cr < 0)
		return cr;

	/* Disable watchdog timer */
	cr &= ~DS1374_REG_CR_WACE;

	return i2c_smbus_write_byte_data(client, DS1374_REG_CR, cr);
}

static const struct watchdog_ops ds1374_wdt_ops = {
	.owner          = THIS_MODULE,
	.start          = ds1374_wdt_start,
	.stop           = ds1374_wdt_stop,
	.set_timeout    = ds1374_wdt_settimeout,
};
#endif /*CONFIG_RTC_DRV_DS1374_WDT*/
/*
 *****************************************************************************
 *
 *	Driver Interface
 *
 *****************************************************************************
 */
static int ds1374_probe(struct i2c_client *client)
{
	struct ds1374 *ds1374;
	int ret;

	ds1374 = devm_kzalloc(&client->dev, sizeof(struct ds1374), GFP_KERNEL);
	if (!ds1374)
		return -ENOMEM;

	ds1374->rtc = devm_rtc_allocate_device(&client->dev);
	if (IS_ERR(ds1374->rtc))
		return PTR_ERR(ds1374->rtc);

	ds1374->client = client;
	i2c_set_clientdata(client, ds1374);

	INIT_WORK(&ds1374->work, ds1374_work);
	mutex_init(&ds1374->mutex);

	ret = ds1374_check_rtc_status(client);
	if (ret)
		return ret;

	if (client->irq > 0) {
		ret = devm_request_irq(&client->dev, client->irq, ds1374_irq, 0,
					"ds1374", client);
		if (ret) {
			dev_err(&client->dev, "unable to request IRQ\n");
			return ret;
		}

		device_set_wakeup_capable(&client->dev, 1);
	}

	ds1374->rtc->ops = &ds1374_rtc_ops;
	ds1374->rtc->range_max = U32_MAX;

	ret = devm_rtc_register_device(ds1374->rtc);
	if (ret)
		return ret;

#ifdef CONFIG_RTC_DRV_DS1374_WDT
	ds1374->wdt.info = &ds1374_wdt_info;
	ds1374->wdt.ops = &ds1374_wdt_ops;
	ds1374->wdt.timeout = TIMER_MARGIN_DEFAULT;
	ds1374->wdt.min_timeout = TIMER_MARGIN_MIN;
	ds1374->wdt.max_timeout = TIMER_MARGIN_MAX;

	watchdog_init_timeout(&ds1374->wdt, wdt_margin, &client->dev);
	watchdog_set_nowayout(&ds1374->wdt, nowayout);
	watchdog_stop_on_reboot(&ds1374->wdt);
	watchdog_stop_on_unregister(&ds1374->wdt);
	watchdog_set_drvdata(&ds1374->wdt, ds1374);
	ds1374_wdt_settimeout(&ds1374->wdt, ds1374->wdt.timeout);

	ret = devm_watchdog_register_device(&client->dev, &ds1374->wdt);
	if (ret)
		return ret;
#endif

	return 0;
}

static void ds1374_remove(struct i2c_client *client)
{
	struct ds1374 *ds1374 = i2c_get_clientdata(client);

	if (client->irq > 0) {
		mutex_lock(&ds1374->mutex);
		ds1374->exiting = 1;
		mutex_unlock(&ds1374->mutex);

		devm_free_irq(&client->dev, client->irq, client);
		cancel_work_sync(&ds1374->work);
	}
}

#ifdef CONFIG_PM_SLEEP
static int ds1374_suspend(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);

	if (client->irq > 0 && device_may_wakeup(&client->dev))
		enable_irq_wake(client->irq);
	return 0;
}

static int ds1374_resume(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);

	if (client->irq > 0 && device_may_wakeup(&client->dev))
		disable_irq_wake(client->irq);
	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(ds1374_pm, ds1374_suspend, ds1374_resume);

static struct i2c_driver ds1374_driver = {
	.driver = {
		.name = "rtc-ds1374",
		.of_match_table = of_match_ptr(ds1374_of_match),
		.pm = &ds1374_pm,
	},
	.probe = ds1374_probe,
	.remove = ds1374_remove,
	.id_table = ds1374_id,
};

module_i2c_driver(ds1374_driver);

MODULE_AUTHOR("Scott Wood <scottwood@freescale.com>");
MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC Driver");
MODULE_LICENSE("GPL");