xref: /openbmc/linux/drivers/rtc/rtc-ds3232.c (revision c819e2cf)
1 /*
2  * RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
3  *
4  * Copyright (C) 2009-2011 Freescale Semiconductor.
5  * Author: Jack Lan <jack.lan@freescale.com>
6  *
7  * This program is free software; you can redistribute  it and/or modify it
8  * under  the terms of  the GNU General  Public License as published by the
9  * Free Software Foundation;  either version 2 of the  License, or (at your
10  * option) any later version.
11  */
12 /*
13  * It would be more efficient to use i2c msgs/i2c_transfer directly but, as
14  * recommened in .../Documentation/i2c/writing-clients section
15  * "Sending and receiving", using SMBus level communication is preferred.
16  */
17 
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/interrupt.h>
21 #include <linux/i2c.h>
22 #include <linux/rtc.h>
23 #include <linux/bcd.h>
24 #include <linux/workqueue.h>
25 #include <linux/slab.h>
26 
27 #define DS3232_REG_SECONDS	0x00
28 #define DS3232_REG_MINUTES	0x01
29 #define DS3232_REG_HOURS	0x02
30 #define DS3232_REG_AMPM		0x02
31 #define DS3232_REG_DAY		0x03
32 #define DS3232_REG_DATE		0x04
33 #define DS3232_REG_MONTH	0x05
34 #define DS3232_REG_CENTURY	0x05
35 #define DS3232_REG_YEAR		0x06
36 #define DS3232_REG_ALARM1         0x07	/* Alarm 1 BASE */
37 #define DS3232_REG_ALARM2         0x0B	/* Alarm 2 BASE */
38 #define DS3232_REG_CR		0x0E	/* Control register */
39 #	define DS3232_REG_CR_nEOSC        0x80
40 #       define DS3232_REG_CR_INTCN        0x04
41 #       define DS3232_REG_CR_A2IE        0x02
42 #       define DS3232_REG_CR_A1IE        0x01
43 
44 #define DS3232_REG_SR	0x0F	/* control/status register */
45 #	define DS3232_REG_SR_OSF   0x80
46 #       define DS3232_REG_SR_BSY   0x04
47 #       define DS3232_REG_SR_A2F   0x02
48 #       define DS3232_REG_SR_A1F   0x01
49 
50 struct ds3232 {
51 	struct i2c_client *client;
52 	struct rtc_device *rtc;
53 	struct work_struct work;
54 
55 	/* The mutex protects alarm operations, and prevents a race
56 	 * between the enable_irq() in the workqueue and the free_irq()
57 	 * in the remove function.
58 	 */
59 	struct mutex mutex;
60 	bool suspended;
61 	int exiting;
62 };
63 
64 static struct i2c_driver ds3232_driver;
65 
66 static int ds3232_check_rtc_status(struct i2c_client *client)
67 {
68 	int ret = 0;
69 	int control, stat;
70 
71 	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
72 	if (stat < 0)
73 		return stat;
74 
75 	if (stat & DS3232_REG_SR_OSF)
76 		dev_warn(&client->dev,
77 				"oscillator discontinuity flagged, "
78 				"time unreliable\n");
79 
80 	stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
81 
82 	ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
83 	if (ret < 0)
84 		return ret;
85 
86 	/* If the alarm is pending, clear it before requesting
87 	 * the interrupt, so an interrupt event isn't reported
88 	 * before everything is initialized.
89 	 */
90 
91 	control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
92 	if (control < 0)
93 		return control;
94 
95 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
96 	control |= DS3232_REG_CR_INTCN;
97 
98 	return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
99 }
100 
101 static int ds3232_read_time(struct device *dev, struct rtc_time *time)
102 {
103 	struct i2c_client *client = to_i2c_client(dev);
104 	int ret;
105 	u8 buf[7];
106 	unsigned int year, month, day, hour, minute, second;
107 	unsigned int week, twelve_hr, am_pm;
108 	unsigned int century, add_century = 0;
109 
110 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
111 
112 	if (ret < 0)
113 		return ret;
114 	if (ret < 7)
115 		return -EIO;
116 
117 	second = buf[0];
118 	minute = buf[1];
119 	hour = buf[2];
120 	week = buf[3];
121 	day = buf[4];
122 	month = buf[5];
123 	year = buf[6];
124 
125 	/* Extract additional information for AM/PM and century */
126 
127 	twelve_hr = hour & 0x40;
128 	am_pm = hour & 0x20;
129 	century = month & 0x80;
130 
131 	/* Write to rtc_time structure */
132 
133 	time->tm_sec = bcd2bin(second);
134 	time->tm_min = bcd2bin(minute);
135 	if (twelve_hr) {
136 		/* Convert to 24 hr */
137 		if (am_pm)
138 			time->tm_hour = bcd2bin(hour & 0x1F) + 12;
139 		else
140 			time->tm_hour = bcd2bin(hour & 0x1F);
141 	} else {
142 		time->tm_hour = bcd2bin(hour);
143 	}
144 
145 	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
146 	time->tm_wday = bcd2bin(week) - 1;
147 	time->tm_mday = bcd2bin(day);
148 	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
149 	time->tm_mon = bcd2bin(month & 0x7F) - 1;
150 	if (century)
151 		add_century = 100;
152 
153 	time->tm_year = bcd2bin(year) + add_century;
154 
155 	return rtc_valid_tm(time);
156 }
157 
158 static int ds3232_set_time(struct device *dev, struct rtc_time *time)
159 {
160 	struct i2c_client *client = to_i2c_client(dev);
161 	u8 buf[7];
162 
163 	/* Extract time from rtc_time and load into ds3232*/
164 
165 	buf[0] = bin2bcd(time->tm_sec);
166 	buf[1] = bin2bcd(time->tm_min);
167 	buf[2] = bin2bcd(time->tm_hour);
168 	/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
169 	buf[3] = bin2bcd(time->tm_wday + 1);
170 	buf[4] = bin2bcd(time->tm_mday); /* Date */
171 	/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
172 	buf[5] = bin2bcd(time->tm_mon + 1);
173 	if (time->tm_year >= 100) {
174 		buf[5] |= 0x80;
175 		buf[6] = bin2bcd(time->tm_year - 100);
176 	} else {
177 		buf[6] = bin2bcd(time->tm_year);
178 	}
179 
180 	return i2c_smbus_write_i2c_block_data(client,
181 					      DS3232_REG_SECONDS, 7, buf);
182 }
183 
184 /*
185  * DS3232 has two alarm, we only use alarm1
186  * According to linux specification, only support one-shot alarm
187  * no periodic alarm mode
188  */
189 static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
190 {
191 	struct i2c_client *client = to_i2c_client(dev);
192 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
193 	int control, stat;
194 	int ret;
195 	u8 buf[4];
196 
197 	mutex_lock(&ds3232->mutex);
198 
199 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
200 	if (ret < 0)
201 		goto out;
202 	stat = ret;
203 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
204 	if (ret < 0)
205 		goto out;
206 	control = ret;
207 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
208 	if (ret < 0)
209 		goto out;
210 
211 	alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
212 	alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
213 	alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
214 	alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);
215 
216 	alarm->time.tm_mon = -1;
217 	alarm->time.tm_year = -1;
218 	alarm->time.tm_wday = -1;
219 	alarm->time.tm_yday = -1;
220 	alarm->time.tm_isdst = -1;
221 
222 	alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
223 	alarm->pending = !!(stat & DS3232_REG_SR_A1F);
224 
225 	ret = 0;
226 out:
227 	mutex_unlock(&ds3232->mutex);
228 	return ret;
229 }
230 
231 /*
232  * linux rtc-module does not support wday alarm
233  * and only 24h time mode supported indeed
234  */
235 static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
236 {
237 	struct i2c_client *client = to_i2c_client(dev);
238 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
239 	int control, stat;
240 	int ret;
241 	u8 buf[4];
242 
243 	if (client->irq <= 0)
244 		return -EINVAL;
245 
246 	mutex_lock(&ds3232->mutex);
247 
248 	buf[0] = bin2bcd(alarm->time.tm_sec);
249 	buf[1] = bin2bcd(alarm->time.tm_min);
250 	buf[2] = bin2bcd(alarm->time.tm_hour);
251 	buf[3] = bin2bcd(alarm->time.tm_mday);
252 
253 	/* clear alarm interrupt enable bit */
254 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
255 	if (ret < 0)
256 		goto out;
257 	control = ret;
258 	control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
259 	ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
260 	if (ret < 0)
261 		goto out;
262 
263 	/* clear any pending alarm flag */
264 	ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
265 	if (ret < 0)
266 		goto out;
267 	stat = ret;
268 	stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
269 	ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
270 	if (ret < 0)
271 		goto out;
272 
273 	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
274 
275 	if (alarm->enabled) {
276 		control |= DS3232_REG_CR_A1IE;
277 		ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
278 	}
279 out:
280 	mutex_unlock(&ds3232->mutex);
281 	return ret;
282 }
283 
284 static void ds3232_update_alarm(struct i2c_client *client)
285 {
286 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
287 	int control;
288 	int ret;
289 	u8 buf[4];
290 
291 	mutex_lock(&ds3232->mutex);
292 
293 	ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
294 	if (ret < 0)
295 		goto unlock;
296 
297 	buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
298 								0x80 : buf[0];
299 	buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
300 								0x80 : buf[1];
301 	buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
302 								0x80 : buf[2];
303 	buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
304 								0x80 : buf[3];
305 
306 	ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
307 	if (ret < 0)
308 		goto unlock;
309 
310 	control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
311 	if (control < 0)
312 		goto unlock;
313 
314 	if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
315 		/* enable alarm1 interrupt */
316 		control |= DS3232_REG_CR_A1IE;
317 	else
318 		/* disable alarm1 interrupt */
319 		control &= ~(DS3232_REG_CR_A1IE);
320 	i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
321 
322 unlock:
323 	mutex_unlock(&ds3232->mutex);
324 }
325 
326 static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
327 {
328 	struct i2c_client *client = to_i2c_client(dev);
329 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
330 
331 	if (client->irq <= 0)
332 		return -EINVAL;
333 
334 	if (enabled)
335 		ds3232->rtc->irq_data |= RTC_AF;
336 	else
337 		ds3232->rtc->irq_data &= ~RTC_AF;
338 
339 	ds3232_update_alarm(client);
340 	return 0;
341 }
342 
343 static irqreturn_t ds3232_irq(int irq, void *dev_id)
344 {
345 	struct i2c_client *client = dev_id;
346 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
347 
348 	disable_irq_nosync(irq);
349 
350 	/*
351 	 * If rtc as a wakeup source, can't schedule the work
352 	 * at system resume flow, because at this time the i2c bus
353 	 * has not been resumed.
354 	 */
355 	if (!ds3232->suspended)
356 		schedule_work(&ds3232->work);
357 
358 	return IRQ_HANDLED;
359 }
360 
361 static void ds3232_work(struct work_struct *work)
362 {
363 	struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
364 	struct i2c_client *client = ds3232->client;
365 	int stat, control;
366 
367 	mutex_lock(&ds3232->mutex);
368 
369 	stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
370 	if (stat < 0)
371 		goto unlock;
372 
373 	if (stat & DS3232_REG_SR_A1F) {
374 		control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
375 		if (control < 0) {
376 			pr_warn("Read DS3232 Control Register error."
377 				"Disable IRQ%d.\n", client->irq);
378 		} else {
379 			/* disable alarm1 interrupt */
380 			control &= ~(DS3232_REG_CR_A1IE);
381 			i2c_smbus_write_byte_data(client, DS3232_REG_CR,
382 						control);
383 
384 			/* clear the alarm pend flag */
385 			stat &= ~DS3232_REG_SR_A1F;
386 			i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
387 
388 			rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
389 
390 			if (!ds3232->exiting)
391 				enable_irq(client->irq);
392 		}
393 	}
394 
395 unlock:
396 	mutex_unlock(&ds3232->mutex);
397 }
398 
399 static const struct rtc_class_ops ds3232_rtc_ops = {
400 	.read_time = ds3232_read_time,
401 	.set_time = ds3232_set_time,
402 	.read_alarm = ds3232_read_alarm,
403 	.set_alarm = ds3232_set_alarm,
404 	.alarm_irq_enable = ds3232_alarm_irq_enable,
405 };
406 
407 static int ds3232_probe(struct i2c_client *client,
408 			const struct i2c_device_id *id)
409 {
410 	struct ds3232 *ds3232;
411 	int ret;
412 
413 	ds3232 = devm_kzalloc(&client->dev, sizeof(struct ds3232), GFP_KERNEL);
414 	if (!ds3232)
415 		return -ENOMEM;
416 
417 	ds3232->client = client;
418 	i2c_set_clientdata(client, ds3232);
419 
420 	INIT_WORK(&ds3232->work, ds3232_work);
421 	mutex_init(&ds3232->mutex);
422 
423 	ret = ds3232_check_rtc_status(client);
424 	if (ret)
425 		return ret;
426 
427 	if (client->irq > 0) {
428 		ret = devm_request_irq(&client->dev, client->irq, ds3232_irq,
429 				       IRQF_SHARED, "ds3232", client);
430 		if (ret) {
431 			dev_err(&client->dev, "unable to request IRQ\n");
432 		}
433 		device_init_wakeup(&client->dev, 1);
434 	}
435 	ds3232->rtc = devm_rtc_device_register(&client->dev, client->name,
436 					  &ds3232_rtc_ops, THIS_MODULE);
437 	return PTR_ERR_OR_ZERO(ds3232->rtc);
438 }
439 
440 static int ds3232_remove(struct i2c_client *client)
441 {
442 	struct ds3232 *ds3232 = i2c_get_clientdata(client);
443 
444 	if (client->irq >= 0) {
445 		mutex_lock(&ds3232->mutex);
446 		ds3232->exiting = 1;
447 		mutex_unlock(&ds3232->mutex);
448 
449 		devm_free_irq(&client->dev, client->irq, client);
450 		cancel_work_sync(&ds3232->work);
451 	}
452 
453 	return 0;
454 }
455 
456 #ifdef CONFIG_PM_SLEEP
457 static int ds3232_suspend(struct device *dev)
458 {
459 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
460 	struct i2c_client *client = to_i2c_client(dev);
461 
462 	if (device_can_wakeup(dev)) {
463 		ds3232->suspended = true;
464 		irq_set_irq_wake(client->irq, 1);
465 	}
466 
467 	return 0;
468 }
469 
470 static int ds3232_resume(struct device *dev)
471 {
472 	struct ds3232 *ds3232 = dev_get_drvdata(dev);
473 	struct i2c_client *client = to_i2c_client(dev);
474 
475 	if (ds3232->suspended) {
476 		ds3232->suspended = false;
477 
478 		/* Clear the hardware alarm pend flag */
479 		schedule_work(&ds3232->work);
480 
481 		irq_set_irq_wake(client->irq, 0);
482 	}
483 
484 	return 0;
485 }
486 #endif
487 
488 static const struct dev_pm_ops ds3232_pm_ops = {
489 	SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
490 };
491 
492 static const struct i2c_device_id ds3232_id[] = {
493 	{ "ds3232", 0 },
494 	{ }
495 };
496 MODULE_DEVICE_TABLE(i2c, ds3232_id);
497 
498 static struct i2c_driver ds3232_driver = {
499 	.driver = {
500 		.name = "rtc-ds3232",
501 		.owner = THIS_MODULE,
502 		.pm	= &ds3232_pm_ops,
503 	},
504 	.probe = ds3232_probe,
505 	.remove = ds3232_remove,
506 	.id_table = ds3232_id,
507 };
508 
509 module_i2c_driver(ds3232_driver);
510 
511 MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
512 MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
513 MODULE_LICENSE("GPL");
514