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1/*
2 * I2C client/driver for the ST M41T80 family of i2c rtc chips.
3 *
4 * Author: Alexander Bigga <ab@mycable.de>
5 *
6 * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
7 *
8 * 2006 (c) mycable GmbH
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15
16#include <linux/bcd.h>
17#include <linux/i2c.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/rtc.h>
22#include <linux/slab.h>
23#include <linux/smp_lock.h>
24#include <linux/string.h>
25#ifdef CONFIG_RTC_DRV_M41T80_WDT
26#include <linux/fs.h>
27#include <linux/ioctl.h>
28#include <linux/miscdevice.h>
29#include <linux/reboot.h>
30#include <linux/watchdog.h>
31#endif
32
33#define M41T80_REG_SSEC	0
34#define M41T80_REG_SEC	1
35#define M41T80_REG_MIN	2
36#define M41T80_REG_HOUR	3
37#define M41T80_REG_WDAY	4
38#define M41T80_REG_DAY	5
39#define M41T80_REG_MON	6
40#define M41T80_REG_YEAR	7
41#define M41T80_REG_ALARM_MON	0xa
42#define M41T80_REG_ALARM_DAY	0xb
43#define M41T80_REG_ALARM_HOUR	0xc
44#define M41T80_REG_ALARM_MIN	0xd
45#define M41T80_REG_ALARM_SEC	0xe
46#define M41T80_REG_FLAGS	0xf
47#define M41T80_REG_SQW	0x13
48
49#define M41T80_DATETIME_REG_SIZE	(M41T80_REG_YEAR + 1)
50#define M41T80_ALARM_REG_SIZE	\
51	(M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
52
53#define M41T80_SEC_ST		(1 << 7)	/* ST: Stop Bit */
54#define M41T80_ALMON_AFE	(1 << 7)	/* AFE: AF Enable Bit */
55#define M41T80_ALMON_SQWE	(1 << 6)	/* SQWE: SQW Enable Bit */
56#define M41T80_ALHOUR_HT	(1 << 6)	/* HT: Halt Update Bit */
57#define M41T80_FLAGS_AF		(1 << 6)	/* AF: Alarm Flag Bit */
58#define M41T80_FLAGS_BATT_LOW	(1 << 4)	/* BL: Battery Low Bit */
59#define M41T80_WATCHDOG_RB2	(1 << 7)	/* RB: Watchdog resolution */
60#define M41T80_WATCHDOG_RB1	(1 << 1)	/* RB: Watchdog resolution */
61#define M41T80_WATCHDOG_RB0	(1 << 0)	/* RB: Watchdog resolution */
62
63#define M41T80_FEATURE_HT	(1 << 0)	/* Halt feature */
64#define M41T80_FEATURE_BL	(1 << 1)	/* Battery low indicator */
65#define M41T80_FEATURE_SQ	(1 << 2)	/* Squarewave feature */
66#define M41T80_FEATURE_WD	(1 << 3)	/* Extra watchdog resolution */
67#define M41T80_FEATURE_SQ_ALT	(1 << 4)	/* RSx bits are in reg 4 */
68
69#define DRV_VERSION "0.05"
70
71static const struct i2c_device_id m41t80_id[] = {
72	{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
73	{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
74	{ "m41t80", M41T80_FEATURE_SQ },
75	{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
76	{ "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
77	{ "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
78	{ "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
79	{ "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
80	{ "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
81	{ "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
82	{ }
83};
84MODULE_DEVICE_TABLE(i2c, m41t80_id);
85
86struct m41t80_data {
87	u8 features;
88	struct rtc_device *rtc;
89};
90
91static int m41t80_get_datetime(struct i2c_client *client,
92			       struct rtc_time *tm)
93{
94	u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
95	struct i2c_msg msgs[] = {
96		{
97			.addr	= client->addr,
98			.flags	= 0,
99			.len	= 1,
100			.buf	= dt_addr,
101		},
102		{
103			.addr	= client->addr,
104			.flags	= I2C_M_RD,
105			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
106			.buf	= buf + M41T80_REG_SEC,
107		},
108	};
109
110	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
111		dev_err(&client->dev, "read error\n");
112		return -EIO;
113	}
114
115	tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
116	tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
117	tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
118	tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
119	tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
120	tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
121
122	/* assume 20YY not 19YY, and ignore the Century Bit */
123	tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
124	return rtc_valid_tm(tm);
125}
126
127/* Sets the given date and time to the real time clock. */
128static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
129{
130	u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
131	u8 *buf = &wbuf[1];
132	u8 dt_addr[1] = { M41T80_REG_SEC };
133	struct i2c_msg msgs_in[] = {
134		{
135			.addr	= client->addr,
136			.flags	= 0,
137			.len	= 1,
138			.buf	= dt_addr,
139		},
140		{
141			.addr	= client->addr,
142			.flags	= I2C_M_RD,
143			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
144			.buf	= buf + M41T80_REG_SEC,
145		},
146	};
147	struct i2c_msg msgs[] = {
148		{
149			.addr	= client->addr,
150			.flags	= 0,
151			.len	= 1 + M41T80_DATETIME_REG_SIZE,
152			.buf	= wbuf,
153		 },
154	};
155
156	/* Read current reg values into buf[1..7] */
157	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
158		dev_err(&client->dev, "read error\n");
159		return -EIO;
160	}
161
162	wbuf[0] = 0; /* offset into rtc's regs */
163	/* Merge time-data and register flags into buf[0..7] */
164	buf[M41T80_REG_SSEC] = 0;
165	buf[M41T80_REG_SEC] =
166		bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
167	buf[M41T80_REG_MIN] =
168		bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
169	buf[M41T80_REG_HOUR] =
170		bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f) ;
171	buf[M41T80_REG_WDAY] =
172		(tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
173	buf[M41T80_REG_DAY] =
174		bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
175	buf[M41T80_REG_MON] =
176		bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
177	/* assume 20YY not 19YY */
178	buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
179
180	if (i2c_transfer(client->adapter, msgs, 1) != 1) {
181		dev_err(&client->dev, "write error\n");
182		return -EIO;
183	}
184	return 0;
185}
186
187#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
188static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
189{
190	struct i2c_client *client = to_i2c_client(dev);
191	struct m41t80_data *clientdata = i2c_get_clientdata(client);
192	u8 reg;
193
194	if (clientdata->features & M41T80_FEATURE_BL) {
195		reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
196		seq_printf(seq, "battery\t\t: %s\n",
197			   (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
198	}
199	return 0;
200}
201#else
202#define m41t80_rtc_proc NULL
203#endif
204
205static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
206{
207	return m41t80_get_datetime(to_i2c_client(dev), tm);
208}
209
210static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
211{
212	return m41t80_set_datetime(to_i2c_client(dev), tm);
213}
214
215#if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
216static int
217m41t80_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
218{
219	struct i2c_client *client = to_i2c_client(dev);
220	int rc;
221
222	switch (cmd) {
223	case RTC_AIE_OFF:
224	case RTC_AIE_ON:
225		break;
226	default:
227		return -ENOIOCTLCMD;
228	}
229
230	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
231	if (rc < 0)
232		goto err;
233	switch (cmd) {
234	case RTC_AIE_OFF:
235		rc &= ~M41T80_ALMON_AFE;
236		break;
237	case RTC_AIE_ON:
238		rc |= M41T80_ALMON_AFE;
239		break;
240	}
241	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
242		goto err;
243	return 0;
244err:
245	return -EIO;
246}
247#else
248#define	m41t80_rtc_ioctl NULL
249#endif
250
251static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
252{
253	struct i2c_client *client = to_i2c_client(dev);
254	u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
255	u8 *buf = &wbuf[1];
256	u8 *reg = buf - M41T80_REG_ALARM_MON;
257	u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
258	struct i2c_msg msgs_in[] = {
259		{
260			.addr	= client->addr,
261			.flags	= 0,
262			.len	= 1,
263			.buf	= dt_addr,
264		},
265		{
266			.addr	= client->addr,
267			.flags	= I2C_M_RD,
268			.len	= M41T80_ALARM_REG_SIZE,
269			.buf	= buf,
270		},
271	};
272	struct i2c_msg msgs[] = {
273		{
274			.addr	= client->addr,
275			.flags	= 0,
276			.len	= 1 + M41T80_ALARM_REG_SIZE,
277			.buf	= wbuf,
278		 },
279	};
280
281	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
282		dev_err(&client->dev, "read error\n");
283		return -EIO;
284	}
285	reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
286	reg[M41T80_REG_ALARM_DAY] = 0;
287	reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
288	reg[M41T80_REG_ALARM_MIN] = 0;
289	reg[M41T80_REG_ALARM_SEC] = 0;
290
291	wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
292	reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
293		bin2bcd(t->time.tm_sec) : 0x80;
294	reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
295		bin2bcd(t->time.tm_min) : 0x80;
296	reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
297		bin2bcd(t->time.tm_hour) : 0x80;
298	reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
299		bin2bcd(t->time.tm_mday) : 0x80;
300	if (t->time.tm_mon >= 0)
301		reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
302	else
303		reg[M41T80_REG_ALARM_DAY] |= 0x40;
304
305	if (i2c_transfer(client->adapter, msgs, 1) != 1) {
306		dev_err(&client->dev, "write error\n");
307		return -EIO;
308	}
309
310	if (t->enabled) {
311		reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
312		if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
313					      reg[M41T80_REG_ALARM_MON]) < 0) {
314			dev_err(&client->dev, "write error\n");
315			return -EIO;
316		}
317	}
318	return 0;
319}
320
321static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
322{
323	struct i2c_client *client = to_i2c_client(dev);
324	u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
325	u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
326	u8 *reg = buf - M41T80_REG_ALARM_MON;
327	struct i2c_msg msgs[] = {
328		{
329			.addr	= client->addr,
330			.flags	= 0,
331			.len	= 1,
332			.buf	= dt_addr,
333		},
334		{
335			.addr	= client->addr,
336			.flags	= I2C_M_RD,
337			.len	= M41T80_ALARM_REG_SIZE + 1,
338			.buf	= buf,
339		},
340	};
341
342	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
343		dev_err(&client->dev, "read error\n");
344		return -EIO;
345	}
346	t->time.tm_sec = -1;
347	t->time.tm_min = -1;
348	t->time.tm_hour = -1;
349	t->time.tm_mday = -1;
350	t->time.tm_mon = -1;
351	if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
352		t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
353	if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
354		t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
355	if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
356		t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
357	if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
358		t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
359	if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
360		t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
361	t->time.tm_year = -1;
362	t->time.tm_wday = -1;
363	t->time.tm_yday = -1;
364	t->time.tm_isdst = -1;
365	t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
366	t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
367	return 0;
368}
369
370static struct rtc_class_ops m41t80_rtc_ops = {
371	.read_time = m41t80_rtc_read_time,
372	.set_time = m41t80_rtc_set_time,
373	.read_alarm = m41t80_rtc_read_alarm,
374	.set_alarm = m41t80_rtc_set_alarm,
375	.proc = m41t80_rtc_proc,
376	.ioctl = m41t80_rtc_ioctl,
377};
378
379#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
380static ssize_t m41t80_sysfs_show_flags(struct device *dev,
381				struct device_attribute *attr, char *buf)
382{
383	struct i2c_client *client = to_i2c_client(dev);
384	int val;
385
386	val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
387	if (val < 0)
388		return -EIO;
389	return sprintf(buf, "%#x\n", val);
390}
391static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
392
393static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
394				struct device_attribute *attr, char *buf)
395{
396	struct i2c_client *client = to_i2c_client(dev);
397	struct m41t80_data *clientdata = i2c_get_clientdata(client);
398	int val, reg_sqw;
399
400	if (!(clientdata->features & M41T80_FEATURE_SQ))
401		return -EINVAL;
402
403	reg_sqw = M41T80_REG_SQW;
404	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
405		reg_sqw = M41T80_REG_WDAY;
406	val = i2c_smbus_read_byte_data(client, reg_sqw);
407	if (val < 0)
408		return -EIO;
409	val = (val >> 4) & 0xf;
410	switch (val) {
411	case 0:
412		break;
413	case 1:
414		val = 32768;
415		break;
416	default:
417		val = 32768 >> val;
418	}
419	return sprintf(buf, "%d\n", val);
420}
421static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
422				struct device_attribute *attr,
423				const char *buf, size_t count)
424{
425	struct i2c_client *client = to_i2c_client(dev);
426	struct m41t80_data *clientdata = i2c_get_clientdata(client);
427	int almon, sqw, reg_sqw;
428	int val = simple_strtoul(buf, NULL, 0);
429
430	if (!(clientdata->features & M41T80_FEATURE_SQ))
431		return -EINVAL;
432
433	if (val) {
434		if (!is_power_of_2(val))
435			return -EINVAL;
436		val = ilog2(val);
437		if (val == 15)
438			val = 1;
439		else if (val < 14)
440			val = 15 - val;
441		else
442			return -EINVAL;
443	}
444	/* disable SQW, set SQW frequency & re-enable */
445	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
446	if (almon < 0)
447		return -EIO;
448	reg_sqw = M41T80_REG_SQW;
449	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
450		reg_sqw = M41T80_REG_WDAY;
451	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
452	if (sqw < 0)
453		return -EIO;
454	sqw = (sqw & 0x0f) | (val << 4);
455	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
456				      almon & ~M41T80_ALMON_SQWE) < 0 ||
457	    i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
458		return -EIO;
459	if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
460					     almon | M41T80_ALMON_SQWE) < 0)
461		return -EIO;
462	return count;
463}
464static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
465		   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
466
467static struct attribute *attrs[] = {
468	&dev_attr_flags.attr,
469	&dev_attr_sqwfreq.attr,
470	NULL,
471};
472static struct attribute_group attr_group = {
473	.attrs = attrs,
474};
475
476static int m41t80_sysfs_register(struct device *dev)
477{
478	return sysfs_create_group(&dev->kobj, &attr_group);
479}
480#else
481static int m41t80_sysfs_register(struct device *dev)
482{
483	return 0;
484}
485#endif
486
487#ifdef CONFIG_RTC_DRV_M41T80_WDT
488/*
489 *****************************************************************************
490 *
491 * Watchdog Driver
492 *
493 *****************************************************************************
494 */
495static struct i2c_client *save_client;
496
497/* Default margin */
498#define WD_TIMO 60		/* 1..31 seconds */
499
500static int wdt_margin = WD_TIMO;
501module_param(wdt_margin, int, 0);
502MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
503
504static unsigned long wdt_is_open;
505static int boot_flag;
506
507/**
508 *	wdt_ping:
509 *
510 *	Reload counter one with the watchdog timeout. We don't bother reloading
511 *	the cascade counter.
512 */
513static void wdt_ping(void)
514{
515	unsigned char i2c_data[2];
516	struct i2c_msg msgs1[1] = {
517		{
518			.addr	= save_client->addr,
519			.flags	= 0,
520			.len	= 2,
521			.buf	= i2c_data,
522		},
523	};
524	struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
525
526	i2c_data[0] = 0x09;		/* watchdog register */
527
528	if (wdt_margin > 31)
529		i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
530	else
531		/*
532		 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
533		 */
534		i2c_data[1] = wdt_margin<<2 | 0x82;
535
536	/*
537	 * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
538	 * that would be an invalid resolution.
539	 */
540	if (clientdata->features & M41T80_FEATURE_WD)
541		i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
542
543	i2c_transfer(save_client->adapter, msgs1, 1);
544}
545
546/**
547 *	wdt_disable:
548 *
549 *	disables watchdog.
550 */
551static void wdt_disable(void)
552{
553	unsigned char i2c_data[2], i2c_buf[0x10];
554	struct i2c_msg msgs0[2] = {
555		{
556			.addr	= save_client->addr,
557			.flags	= 0,
558			.len	= 1,
559			.buf	= i2c_data,
560		},
561		{
562			.addr	= save_client->addr,
563			.flags	= I2C_M_RD,
564			.len	= 1,
565			.buf	= i2c_buf,
566		},
567	};
568	struct i2c_msg msgs1[1] = {
569		{
570			.addr	= save_client->addr,
571			.flags	= 0,
572			.len	= 2,
573			.buf	= i2c_data,
574		},
575	};
576
577	i2c_data[0] = 0x09;
578	i2c_transfer(save_client->adapter, msgs0, 2);
579
580	i2c_data[0] = 0x09;
581	i2c_data[1] = 0x00;
582	i2c_transfer(save_client->adapter, msgs1, 1);
583}
584
585/**
586 *	wdt_write:
587 *	@file: file handle to the watchdog
588 *	@buf: buffer to write (unused as data does not matter here
589 *	@count: count of bytes
590 *	@ppos: pointer to the position to write. No seeks allowed
591 *
592 *	A write to a watchdog device is defined as a keepalive signal. Any
593 *	write of data will do, as we we don't define content meaning.
594 */
595static ssize_t wdt_write(struct file *file, const char __user *buf,
596			 size_t count, loff_t *ppos)
597{
598	if (count) {
599		wdt_ping();
600		return 1;
601	}
602	return 0;
603}
604
605static ssize_t wdt_read(struct file *file, char __user *buf,
606			size_t count, loff_t *ppos)
607{
608	return 0;
609}
610
611/**
612 *	wdt_ioctl:
613 *	@inode: inode of the device
614 *	@file: file handle to the device
615 *	@cmd: watchdog command
616 *	@arg: argument pointer
617 *
618 *	The watchdog API defines a common set of functions for all watchdogs
619 *	according to their available features. We only actually usefully support
620 *	querying capabilities and current status.
621 */
622static int wdt_ioctl(struct file *file, unsigned int cmd,
623		     unsigned long arg)
624{
625	int new_margin, rv;
626	static struct watchdog_info ident = {
627		.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
628			WDIOF_SETTIMEOUT,
629		.firmware_version = 1,
630		.identity = "M41T80 WTD"
631	};
632
633	switch (cmd) {
634	case WDIOC_GETSUPPORT:
635		return copy_to_user((struct watchdog_info __user *)arg, &ident,
636				    sizeof(ident)) ? -EFAULT : 0;
637
638	case WDIOC_GETSTATUS:
639	case WDIOC_GETBOOTSTATUS:
640		return put_user(boot_flag, (int __user *)arg);
641	case WDIOC_KEEPALIVE:
642		wdt_ping();
643		return 0;
644	case WDIOC_SETTIMEOUT:
645		if (get_user(new_margin, (int __user *)arg))
646			return -EFAULT;
647		/* Arbitrary, can't find the card's limits */
648		if (new_margin < 1 || new_margin > 124)
649			return -EINVAL;
650		wdt_margin = new_margin;
651		wdt_ping();
652		/* Fall */
653	case WDIOC_GETTIMEOUT:
654		return put_user(wdt_margin, (int __user *)arg);
655
656	case WDIOC_SETOPTIONS:
657		if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
658			return -EFAULT;
659
660		if (rv & WDIOS_DISABLECARD) {
661			pr_info("rtc-m41t80: disable watchdog\n");
662			wdt_disable();
663		}
664
665		if (rv & WDIOS_ENABLECARD) {
666			pr_info("rtc-m41t80: enable watchdog\n");
667			wdt_ping();
668		}
669
670		return -EINVAL;
671	}
672	return -ENOTTY;
673}
674
675static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
676			       unsigned long arg)
677{
678	int ret;
679
680	lock_kernel();
681	ret = wdt_ioctl(file, cmd, arg);
682	unlock_kernel();
683
684	return ret;
685}
686
687/**
688 *	wdt_open:
689 *	@inode: inode of device
690 *	@file: file handle to device
691 *
692 */
693static int wdt_open(struct inode *inode, struct file *file)
694{
695	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
696		lock_kernel();
697		if (test_and_set_bit(0, &wdt_is_open)) {
698			unlock_kernel();
699			return -EBUSY;
700		}
701		/*
702		 *	Activate
703		 */
704		wdt_is_open = 1;
705		unlock_kernel();
706		return nonseekable_open(inode, file);
707	}
708	return -ENODEV;
709}
710
711/**
712 *	wdt_close:
713 *	@inode: inode to board
714 *	@file: file handle to board
715 *
716 */
717static int wdt_release(struct inode *inode, struct file *file)
718{
719	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
720		clear_bit(0, &wdt_is_open);
721	return 0;
722}
723
724/**
725 *	notify_sys:
726 *	@this: our notifier block
727 *	@code: the event being reported
728 *	@unused: unused
729 *
730 *	Our notifier is called on system shutdowns. We want to turn the card
731 *	off at reboot otherwise the machine will reboot again during memory
732 *	test or worse yet during the following fsck. This would suck, in fact
733 *	trust me - if it happens it does suck.
734 */
735static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
736			  void *unused)
737{
738	if (code == SYS_DOWN || code == SYS_HALT)
739		/* Disable Watchdog */
740		wdt_disable();
741	return NOTIFY_DONE;
742}
743
744static const struct file_operations wdt_fops = {
745	.owner	= THIS_MODULE,
746	.read	= wdt_read,
747	.unlocked_ioctl = wdt_unlocked_ioctl,
748	.write	= wdt_write,
749	.open	= wdt_open,
750	.release = wdt_release,
751};
752
753static struct miscdevice wdt_dev = {
754	.minor = WATCHDOG_MINOR,
755	.name = "watchdog",
756	.fops = &wdt_fops,
757};
758
759/*
760 *	The WDT card needs to learn about soft shutdowns in order to
761 *	turn the timebomb registers off.
762 */
763static struct notifier_block wdt_notifier = {
764	.notifier_call = wdt_notify_sys,
765};
766#endif /* CONFIG_RTC_DRV_M41T80_WDT */
767
768/*
769 *****************************************************************************
770 *
771 *	Driver Interface
772 *
773 *****************************************************************************
774 */
775static int m41t80_probe(struct i2c_client *client,
776			const struct i2c_device_id *id)
777{
778	int rc = 0;
779	struct rtc_device *rtc = NULL;
780	struct rtc_time tm;
781	struct m41t80_data *clientdata = NULL;
782
783	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
784				     | I2C_FUNC_SMBUS_BYTE_DATA)) {
785		rc = -ENODEV;
786		goto exit;
787	}
788
789	dev_info(&client->dev,
790		 "chip found, driver version " DRV_VERSION "\n");
791
792	clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
793	if (!clientdata) {
794		rc = -ENOMEM;
795		goto exit;
796	}
797
798	rtc = rtc_device_register(client->name, &client->dev,
799				  &m41t80_rtc_ops, THIS_MODULE);
800	if (IS_ERR(rtc)) {
801		rc = PTR_ERR(rtc);
802		rtc = NULL;
803		goto exit;
804	}
805
806	clientdata->rtc = rtc;
807	clientdata->features = id->driver_data;
808	i2c_set_clientdata(client, clientdata);
809
810	/* Make sure HT (Halt Update) bit is cleared */
811	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
812	if (rc < 0)
813		goto ht_err;
814
815	if (rc & M41T80_ALHOUR_HT) {
816		if (clientdata->features & M41T80_FEATURE_HT) {
817			m41t80_get_datetime(client, &tm);
818			dev_info(&client->dev, "HT bit was set!\n");
819			dev_info(&client->dev,
820				 "Power Down at "
821				 "%04i-%02i-%02i %02i:%02i:%02i\n",
822				 tm.tm_year + 1900,
823				 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
824				 tm.tm_min, tm.tm_sec);
825		}
826		if (i2c_smbus_write_byte_data(client,
827					      M41T80_REG_ALARM_HOUR,
828					      rc & ~M41T80_ALHOUR_HT) < 0)
829			goto ht_err;
830	}
831
832	/* Make sure ST (stop) bit is cleared */
833	rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
834	if (rc < 0)
835		goto st_err;
836
837	if (rc & M41T80_SEC_ST) {
838		if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
839					      rc & ~M41T80_SEC_ST) < 0)
840			goto st_err;
841	}
842
843	rc = m41t80_sysfs_register(&client->dev);
844	if (rc)
845		goto exit;
846
847#ifdef CONFIG_RTC_DRV_M41T80_WDT
848	if (clientdata->features & M41T80_FEATURE_HT) {
849		save_client = client;
850		rc = misc_register(&wdt_dev);
851		if (rc)
852			goto exit;
853		rc = register_reboot_notifier(&wdt_notifier);
854		if (rc) {
855			misc_deregister(&wdt_dev);
856			goto exit;
857		}
858	}
859#endif
860	return 0;
861
862st_err:
863	rc = -EIO;
864	dev_err(&client->dev, "Can't clear ST bit\n");
865	goto exit;
866ht_err:
867	rc = -EIO;
868	dev_err(&client->dev, "Can't clear HT bit\n");
869	goto exit;
870
871exit:
872	if (rtc)
873		rtc_device_unregister(rtc);
874	kfree(clientdata);
875	return rc;
876}
877
878static int m41t80_remove(struct i2c_client *client)
879{
880	struct m41t80_data *clientdata = i2c_get_clientdata(client);
881	struct rtc_device *rtc = clientdata->rtc;
882
883#ifdef CONFIG_RTC_DRV_M41T80_WDT
884	if (clientdata->features & M41T80_FEATURE_HT) {
885		misc_deregister(&wdt_dev);
886		unregister_reboot_notifier(&wdt_notifier);
887	}
888#endif
889	if (rtc)
890		rtc_device_unregister(rtc);
891	kfree(clientdata);
892
893	return 0;
894}
895
896static struct i2c_driver m41t80_driver = {
897	.driver = {
898		.name = "rtc-m41t80",
899	},
900	.probe = m41t80_probe,
901	.remove = m41t80_remove,
902	.id_table = m41t80_id,
903};
904
905static int __init m41t80_rtc_init(void)
906{
907	return i2c_add_driver(&m41t80_driver);
908}
909
910static void __exit m41t80_rtc_exit(void)
911{
912	i2c_del_driver(&m41t80_driver);
913}
914
915MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
916MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
917MODULE_LICENSE("GPL");
918MODULE_VERSION(DRV_VERSION);
919
920module_init(m41t80_rtc_init);
921module_exit(m41t80_rtc_exit);
922