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
50struct 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
64static struct i2c_driver ds3232_driver;
65
66static 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
101static 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
158static 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 */
189static 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;
226out:
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 */
235static 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	}
279out:
280	mutex_unlock(&ds3232->mutex);
281	return ret;
282}
283
284static 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
322unlock:
323	mutex_unlock(&ds3232->mutex);
324}
325
326static 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
343static 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
361static 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
395unlock:
396	mutex_unlock(&ds3232->mutex);
397}
398
399static 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
407static 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
440static 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
457static 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
470static 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
488static const struct dev_pm_ops ds3232_pm_ops = {
489	SET_SYSTEM_SLEEP_PM_OPS(ds3232_suspend, ds3232_resume)
490};
491
492static const struct i2c_device_id ds3232_id[] = {
493	{ "ds3232", 0 },
494	{ }
495};
496MODULE_DEVICE_TABLE(i2c, ds3232_id);
497
498static 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
509module_i2c_driver(ds3232_driver);
510
511MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
512MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
513MODULE_LICENSE("GPL");
514