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/mutex.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 DEFINE_MUTEX(m41t80_rtc_mutex);
 72static const struct i2c_device_id m41t80_id[] = {
 73	{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
 74	{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
 75	{ "m41t80", M41T80_FEATURE_SQ },
 76	{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
 77	{ "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 78	{ "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 79	{ "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 80	{ "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 81	{ "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 82	{ "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
 83	{ }
 84};
 85MODULE_DEVICE_TABLE(i2c, m41t80_id);
 86
 87struct m41t80_data {
 88	u8 features;
 89	struct rtc_device *rtc;
 90};
 91
 92static int m41t80_get_datetime(struct i2c_client *client,
 93			       struct rtc_time *tm)
 94{
 95	u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
 96	struct i2c_msg msgs[] = {
 97		{
 98			.addr	= client->addr,
 99			.flags	= 0,
100			.len	= 1,
101			.buf	= dt_addr,
102		},
103		{
104			.addr	= client->addr,
105			.flags	= I2C_M_RD,
106			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
107			.buf	= buf + M41T80_REG_SEC,
108		},
109	};
110
111	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
112		dev_err(&client->dev, "read error\n");
113		return -EIO;
114	}
115
116	tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
117	tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
118	tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
119	tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
120	tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
121	tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
122
123	/* assume 20YY not 19YY, and ignore the Century Bit */
124	tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
125	return rtc_valid_tm(tm);
126}
127
128/* Sets the given date and time to the real time clock. */
129static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
130{
131	u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
132	u8 *buf = &wbuf[1];
133	u8 dt_addr[1] = { M41T80_REG_SEC };
134	struct i2c_msg msgs_in[] = {
135		{
136			.addr	= client->addr,
137			.flags	= 0,
138			.len	= 1,
139			.buf	= dt_addr,
140		},
141		{
142			.addr	= client->addr,
143			.flags	= I2C_M_RD,
144			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
145			.buf	= buf + M41T80_REG_SEC,
146		},
147	};
148	struct i2c_msg msgs[] = {
149		{
150			.addr	= client->addr,
151			.flags	= 0,
152			.len	= 1 + M41T80_DATETIME_REG_SIZE,
153			.buf	= wbuf,
154		 },
155	};
156
157	/* Read current reg values into buf[1..7] */
158	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
159		dev_err(&client->dev, "read error\n");
160		return -EIO;
161	}
162
163	wbuf[0] = 0; /* offset into rtc's regs */
164	/* Merge time-data and register flags into buf[0..7] */
165	buf[M41T80_REG_SSEC] = 0;
166	buf[M41T80_REG_SEC] =
167		bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
168	buf[M41T80_REG_MIN] =
169		bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
170	buf[M41T80_REG_HOUR] =
171		bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f) ;
172	buf[M41T80_REG_WDAY] =
173		(tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
174	buf[M41T80_REG_DAY] =
175		bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
176	buf[M41T80_REG_MON] =
177		bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
178	/* assume 20YY not 19YY */
179	buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
180
181	if (i2c_transfer(client->adapter, msgs, 1) != 1) {
182		dev_err(&client->dev, "write error\n");
183		return -EIO;
184	}
185	return 0;
186}
187
188#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
189static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
190{
191	struct i2c_client *client = to_i2c_client(dev);
192	struct m41t80_data *clientdata = i2c_get_clientdata(client);
193	u8 reg;
194
195	if (clientdata->features & M41T80_FEATURE_BL) {
196		reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
197		seq_printf(seq, "battery\t\t: %s\n",
198			   (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
199	}
200	return 0;
201}
202#else
203#define m41t80_rtc_proc NULL
204#endif
205
206static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
207{
208	return m41t80_get_datetime(to_i2c_client(dev), tm);
209}
210
211static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
212{
213	return m41t80_set_datetime(to_i2c_client(dev), tm);
214}
215
216static int m41t80_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
217{
218	struct i2c_client *client = to_i2c_client(dev);
219	int rc;
220
221	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
222	if (rc < 0)
223		goto err;
224
225	if (enabled)
226		rc |= M41T80_ALMON_AFE;
227	else
228		rc &= ~M41T80_ALMON_AFE;
229
230	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, rc) < 0)
231		goto err;
232
233	return 0;
234err:
235	return -EIO;
236}
237
238static int m41t80_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
239{
240	struct i2c_client *client = to_i2c_client(dev);
241	u8 wbuf[1 + M41T80_ALARM_REG_SIZE];
242	u8 *buf = &wbuf[1];
243	u8 *reg = buf - M41T80_REG_ALARM_MON;
244	u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
245	struct i2c_msg msgs_in[] = {
246		{
247			.addr	= client->addr,
248			.flags	= 0,
249			.len	= 1,
250			.buf	= dt_addr,
251		},
252		{
253			.addr	= client->addr,
254			.flags	= I2C_M_RD,
255			.len	= M41T80_ALARM_REG_SIZE,
256			.buf	= buf,
257		},
258	};
259	struct i2c_msg msgs[] = {
260		{
261			.addr	= client->addr,
262			.flags	= 0,
263			.len	= 1 + M41T80_ALARM_REG_SIZE,
264			.buf	= wbuf,
265		 },
266	};
267
268	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
269		dev_err(&client->dev, "read error\n");
270		return -EIO;
271	}
272	reg[M41T80_REG_ALARM_MON] &= ~(0x1f | M41T80_ALMON_AFE);
273	reg[M41T80_REG_ALARM_DAY] = 0;
274	reg[M41T80_REG_ALARM_HOUR] &= ~(0x3f | 0x80);
275	reg[M41T80_REG_ALARM_MIN] = 0;
276	reg[M41T80_REG_ALARM_SEC] = 0;
277
278	wbuf[0] = M41T80_REG_ALARM_MON; /* offset into rtc's regs */
279	reg[M41T80_REG_ALARM_SEC] |= t->time.tm_sec >= 0 ?
280		bin2bcd(t->time.tm_sec) : 0x80;
281	reg[M41T80_REG_ALARM_MIN] |= t->time.tm_min >= 0 ?
282		bin2bcd(t->time.tm_min) : 0x80;
283	reg[M41T80_REG_ALARM_HOUR] |= t->time.tm_hour >= 0 ?
284		bin2bcd(t->time.tm_hour) : 0x80;
285	reg[M41T80_REG_ALARM_DAY] |= t->time.tm_mday >= 0 ?
286		bin2bcd(t->time.tm_mday) : 0x80;
287	if (t->time.tm_mon >= 0)
288		reg[M41T80_REG_ALARM_MON] |= bin2bcd(t->time.tm_mon + 1);
289	else
290		reg[M41T80_REG_ALARM_DAY] |= 0x40;
291
292	if (i2c_transfer(client->adapter, msgs, 1) != 1) {
293		dev_err(&client->dev, "write error\n");
294		return -EIO;
295	}
296
297	if (t->enabled) {
298		reg[M41T80_REG_ALARM_MON] |= M41T80_ALMON_AFE;
299		if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
300					      reg[M41T80_REG_ALARM_MON]) < 0) {
301			dev_err(&client->dev, "write error\n");
302			return -EIO;
303		}
304	}
305	return 0;
306}
307
308static int m41t80_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *t)
309{
310	struct i2c_client *client = to_i2c_client(dev);
311	u8 buf[M41T80_ALARM_REG_SIZE + 1]; /* all alarm regs and flags */
312	u8 dt_addr[1] = { M41T80_REG_ALARM_MON };
313	u8 *reg = buf - M41T80_REG_ALARM_MON;
314	struct i2c_msg msgs[] = {
315		{
316			.addr	= client->addr,
317			.flags	= 0,
318			.len	= 1,
319			.buf	= dt_addr,
320		},
321		{
322			.addr	= client->addr,
323			.flags	= I2C_M_RD,
324			.len	= M41T80_ALARM_REG_SIZE + 1,
325			.buf	= buf,
326		},
327	};
328
329	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
330		dev_err(&client->dev, "read error\n");
331		return -EIO;
332	}
333	t->time.tm_sec = -1;
334	t->time.tm_min = -1;
335	t->time.tm_hour = -1;
336	t->time.tm_mday = -1;
337	t->time.tm_mon = -1;
338	if (!(reg[M41T80_REG_ALARM_SEC] & 0x80))
339		t->time.tm_sec = bcd2bin(reg[M41T80_REG_ALARM_SEC] & 0x7f);
340	if (!(reg[M41T80_REG_ALARM_MIN] & 0x80))
341		t->time.tm_min = bcd2bin(reg[M41T80_REG_ALARM_MIN] & 0x7f);
342	if (!(reg[M41T80_REG_ALARM_HOUR] & 0x80))
343		t->time.tm_hour = bcd2bin(reg[M41T80_REG_ALARM_HOUR] & 0x3f);
344	if (!(reg[M41T80_REG_ALARM_DAY] & 0x80))
345		t->time.tm_mday = bcd2bin(reg[M41T80_REG_ALARM_DAY] & 0x3f);
346	if (!(reg[M41T80_REG_ALARM_DAY] & 0x40))
347		t->time.tm_mon = bcd2bin(reg[M41T80_REG_ALARM_MON] & 0x1f) - 1;
348	t->time.tm_year = -1;
349	t->time.tm_wday = -1;
350	t->time.tm_yday = -1;
351	t->time.tm_isdst = -1;
352	t->enabled = !!(reg[M41T80_REG_ALARM_MON] & M41T80_ALMON_AFE);
353	t->pending = !!(reg[M41T80_REG_FLAGS] & M41T80_FLAGS_AF);
354	return 0;
355}
356
357static struct rtc_class_ops m41t80_rtc_ops = {
358	.read_time = m41t80_rtc_read_time,
359	.set_time = m41t80_rtc_set_time,
 
 
 
 
360	.read_alarm = m41t80_rtc_read_alarm,
361	.set_alarm = m41t80_rtc_set_alarm,
 
362	.proc = m41t80_rtc_proc,
 
 
 
363	.alarm_irq_enable = m41t80_rtc_alarm_irq_enable,
 
364};
365
366#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
367static ssize_t m41t80_sysfs_show_flags(struct device *dev,
368				struct device_attribute *attr, char *buf)
369{
370	struct i2c_client *client = to_i2c_client(dev);
371	int val;
372
373	val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
374	if (val < 0)
375		return -EIO;
376	return sprintf(buf, "%#x\n", val);
377}
378static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
379
380static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
381				struct device_attribute *attr, char *buf)
382{
383	struct i2c_client *client = to_i2c_client(dev);
384	struct m41t80_data *clientdata = i2c_get_clientdata(client);
385	int val, reg_sqw;
386
387	if (!(clientdata->features & M41T80_FEATURE_SQ))
388		return -EINVAL;
389
390	reg_sqw = M41T80_REG_SQW;
391	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
392		reg_sqw = M41T80_REG_WDAY;
393	val = i2c_smbus_read_byte_data(client, reg_sqw);
394	if (val < 0)
395		return -EIO;
396	val = (val >> 4) & 0xf;
397	switch (val) {
398	case 0:
399		break;
400	case 1:
401		val = 32768;
402		break;
403	default:
404		val = 32768 >> val;
405	}
406	return sprintf(buf, "%d\n", val);
407}
408static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
409				struct device_attribute *attr,
410				const char *buf, size_t count)
411{
412	struct i2c_client *client = to_i2c_client(dev);
413	struct m41t80_data *clientdata = i2c_get_clientdata(client);
414	int almon, sqw, reg_sqw;
415	int val = simple_strtoul(buf, NULL, 0);
416
417	if (!(clientdata->features & M41T80_FEATURE_SQ))
418		return -EINVAL;
419
420	if (val) {
421		if (!is_power_of_2(val))
422			return -EINVAL;
423		val = ilog2(val);
424		if (val == 15)
425			val = 1;
426		else if (val < 14)
427			val = 15 - val;
428		else
429			return -EINVAL;
430	}
431	/* disable SQW, set SQW frequency & re-enable */
432	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
433	if (almon < 0)
434		return -EIO;
435	reg_sqw = M41T80_REG_SQW;
436	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
437		reg_sqw = M41T80_REG_WDAY;
438	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
439	if (sqw < 0)
440		return -EIO;
441	sqw = (sqw & 0x0f) | (val << 4);
442	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
443				      almon & ~M41T80_ALMON_SQWE) < 0 ||
444	    i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
445		return -EIO;
446	if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
447					     almon | M41T80_ALMON_SQWE) < 0)
448		return -EIO;
449	return count;
450}
451static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
452		   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
453
454static struct attribute *attrs[] = {
455	&dev_attr_flags.attr,
456	&dev_attr_sqwfreq.attr,
457	NULL,
458};
459static struct attribute_group attr_group = {
460	.attrs = attrs,
461};
462
463static int m41t80_sysfs_register(struct device *dev)
464{
465	return sysfs_create_group(&dev->kobj, &attr_group);
466}
467#else
468static int m41t80_sysfs_register(struct device *dev)
469{
470	return 0;
471}
472#endif
473
474#ifdef CONFIG_RTC_DRV_M41T80_WDT
475/*
476 *****************************************************************************
477 *
478 * Watchdog Driver
479 *
480 *****************************************************************************
481 */
482static struct i2c_client *save_client;
483
484/* Default margin */
485#define WD_TIMO 60		/* 1..31 seconds */
486
487static int wdt_margin = WD_TIMO;
488module_param(wdt_margin, int, 0);
489MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
490
491static unsigned long wdt_is_open;
492static int boot_flag;
493
494/**
495 *	wdt_ping:
496 *
497 *	Reload counter one with the watchdog timeout. We don't bother reloading
498 *	the cascade counter.
499 */
500static void wdt_ping(void)
501{
502	unsigned char i2c_data[2];
503	struct i2c_msg msgs1[1] = {
504		{
505			.addr	= save_client->addr,
506			.flags	= 0,
507			.len	= 2,
508			.buf	= i2c_data,
509		},
510	};
511	struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
512
513	i2c_data[0] = 0x09;		/* watchdog register */
514
515	if (wdt_margin > 31)
516		i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
517	else
518		/*
519		 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
520		 */
521		i2c_data[1] = wdt_margin<<2 | 0x82;
522
523	/*
524	 * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
525	 * that would be an invalid resolution.
526	 */
527	if (clientdata->features & M41T80_FEATURE_WD)
528		i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
529
530	i2c_transfer(save_client->adapter, msgs1, 1);
531}
532
533/**
534 *	wdt_disable:
535 *
536 *	disables watchdog.
537 */
538static void wdt_disable(void)
539{
540	unsigned char i2c_data[2], i2c_buf[0x10];
541	struct i2c_msg msgs0[2] = {
542		{
543			.addr	= save_client->addr,
544			.flags	= 0,
545			.len	= 1,
546			.buf	= i2c_data,
547		},
548		{
549			.addr	= save_client->addr,
550			.flags	= I2C_M_RD,
551			.len	= 1,
552			.buf	= i2c_buf,
553		},
554	};
555	struct i2c_msg msgs1[1] = {
556		{
557			.addr	= save_client->addr,
558			.flags	= 0,
559			.len	= 2,
560			.buf	= i2c_data,
561		},
562	};
563
564	i2c_data[0] = 0x09;
565	i2c_transfer(save_client->adapter, msgs0, 2);
566
567	i2c_data[0] = 0x09;
568	i2c_data[1] = 0x00;
569	i2c_transfer(save_client->adapter, msgs1, 1);
570}
571
572/**
573 *	wdt_write:
574 *	@file: file handle to the watchdog
575 *	@buf: buffer to write (unused as data does not matter here
576 *	@count: count of bytes
577 *	@ppos: pointer to the position to write. No seeks allowed
578 *
579 *	A write to a watchdog device is defined as a keepalive signal. Any
580 *	write of data will do, as we we don't define content meaning.
581 */
582static ssize_t wdt_write(struct file *file, const char __user *buf,
583			 size_t count, loff_t *ppos)
584{
585	if (count) {
586		wdt_ping();
587		return 1;
588	}
589	return 0;
590}
591
592static ssize_t wdt_read(struct file *file, char __user *buf,
593			size_t count, loff_t *ppos)
594{
595	return 0;
596}
597
598/**
599 *	wdt_ioctl:
600 *	@inode: inode of the device
601 *	@file: file handle to the device
602 *	@cmd: watchdog command
603 *	@arg: argument pointer
604 *
605 *	The watchdog API defines a common set of functions for all watchdogs
606 *	according to their available features. We only actually usefully support
607 *	querying capabilities and current status.
608 */
609static int wdt_ioctl(struct file *file, unsigned int cmd,
610		     unsigned long arg)
611{
612	int new_margin, rv;
613	static struct watchdog_info ident = {
614		.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
615			WDIOF_SETTIMEOUT,
616		.firmware_version = 1,
617		.identity = "M41T80 WTD"
618	};
619
620	switch (cmd) {
621	case WDIOC_GETSUPPORT:
622		return copy_to_user((struct watchdog_info __user *)arg, &ident,
623				    sizeof(ident)) ? -EFAULT : 0;
624
625	case WDIOC_GETSTATUS:
626	case WDIOC_GETBOOTSTATUS:
627		return put_user(boot_flag, (int __user *)arg);
628	case WDIOC_KEEPALIVE:
629		wdt_ping();
630		return 0;
631	case WDIOC_SETTIMEOUT:
632		if (get_user(new_margin, (int __user *)arg))
633			return -EFAULT;
634		/* Arbitrary, can't find the card's limits */
635		if (new_margin < 1 || new_margin > 124)
636			return -EINVAL;
637		wdt_margin = new_margin;
638		wdt_ping();
639		/* Fall */
640	case WDIOC_GETTIMEOUT:
641		return put_user(wdt_margin, (int __user *)arg);
642
643	case WDIOC_SETOPTIONS:
644		if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
645			return -EFAULT;
646
647		if (rv & WDIOS_DISABLECARD) {
648			pr_info("rtc-m41t80: disable watchdog\n");
649			wdt_disable();
650		}
651
652		if (rv & WDIOS_ENABLECARD) {
653			pr_info("rtc-m41t80: enable watchdog\n");
654			wdt_ping();
655		}
656
657		return -EINVAL;
658	}
659	return -ENOTTY;
660}
661
662static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
663			       unsigned long arg)
664{
665	int ret;
666
667	mutex_lock(&m41t80_rtc_mutex);
668	ret = wdt_ioctl(file, cmd, arg);
669	mutex_unlock(&m41t80_rtc_mutex);
670
671	return ret;
672}
673
674/**
675 *	wdt_open:
676 *	@inode: inode of device
677 *	@file: file handle to device
678 *
679 */
680static int wdt_open(struct inode *inode, struct file *file)
681{
682	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
683		mutex_lock(&m41t80_rtc_mutex);
684		if (test_and_set_bit(0, &wdt_is_open)) {
685			mutex_unlock(&m41t80_rtc_mutex);
686			return -EBUSY;
687		}
688		/*
689		 *	Activate
690		 */
691		wdt_is_open = 1;
692		mutex_unlock(&m41t80_rtc_mutex);
693		return nonseekable_open(inode, file);
694	}
695	return -ENODEV;
696}
697
698/**
699 *	wdt_close:
700 *	@inode: inode to board
701 *	@file: file handle to board
702 *
703 */
704static int wdt_release(struct inode *inode, struct file *file)
705{
706	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
707		clear_bit(0, &wdt_is_open);
708	return 0;
709}
710
711/**
712 *	notify_sys:
713 *	@this: our notifier block
714 *	@code: the event being reported
715 *	@unused: unused
716 *
717 *	Our notifier is called on system shutdowns. We want to turn the card
718 *	off at reboot otherwise the machine will reboot again during memory
719 *	test or worse yet during the following fsck. This would suck, in fact
720 *	trust me - if it happens it does suck.
721 */
722static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
723			  void *unused)
724{
725	if (code == SYS_DOWN || code == SYS_HALT)
726		/* Disable Watchdog */
727		wdt_disable();
728	return NOTIFY_DONE;
729}
730
731static const struct file_operations wdt_fops = {
732	.owner	= THIS_MODULE,
733	.read	= wdt_read,
734	.unlocked_ioctl = wdt_unlocked_ioctl,
735	.write	= wdt_write,
736	.open	= wdt_open,
737	.release = wdt_release,
738	.llseek = no_llseek,
739};
740
741static struct miscdevice wdt_dev = {
742	.minor = WATCHDOG_MINOR,
743	.name = "watchdog",
744	.fops = &wdt_fops,
745};
746
747/*
748 *	The WDT card needs to learn about soft shutdowns in order to
749 *	turn the timebomb registers off.
750 */
751static struct notifier_block wdt_notifier = {
752	.notifier_call = wdt_notify_sys,
753};
754#endif /* CONFIG_RTC_DRV_M41T80_WDT */
755
756/*
757 *****************************************************************************
758 *
759 *	Driver Interface
760 *
761 *****************************************************************************
762 */
763static int m41t80_probe(struct i2c_client *client,
764			const struct i2c_device_id *id)
765{
766	int rc = 0;
767	struct rtc_device *rtc = NULL;
768	struct rtc_time tm;
769	struct m41t80_data *clientdata = NULL;
770
771	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
772				     | I2C_FUNC_SMBUS_BYTE_DATA)) {
773		rc = -ENODEV;
774		goto exit;
775	}
776
777	dev_info(&client->dev,
778		 "chip found, driver version " DRV_VERSION "\n");
779
780	clientdata = kzalloc(sizeof(*clientdata), GFP_KERNEL);
781	if (!clientdata) {
782		rc = -ENOMEM;
783		goto exit;
784	}
785
786	clientdata->features = id->driver_data;
787	i2c_set_clientdata(client, clientdata);
788
789	rtc = rtc_device_register(client->name, &client->dev,
790				  &m41t80_rtc_ops, THIS_MODULE);
791	if (IS_ERR(rtc)) {
792		rc = PTR_ERR(rtc);
793		rtc = NULL;
794		goto exit;
795	}
796
797	clientdata->rtc = rtc;
798
799	/* Make sure HT (Halt Update) bit is cleared */
800	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
801	if (rc < 0)
802		goto ht_err;
803
804	if (rc & M41T80_ALHOUR_HT) {
805		if (clientdata->features & M41T80_FEATURE_HT) {
806			m41t80_get_datetime(client, &tm);
807			dev_info(&client->dev, "HT bit was set!\n");
808			dev_info(&client->dev,
809				 "Power Down at "
810				 "%04i-%02i-%02i %02i:%02i:%02i\n",
811				 tm.tm_year + 1900,
812				 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
813				 tm.tm_min, tm.tm_sec);
814		}
815		if (i2c_smbus_write_byte_data(client,
816					      M41T80_REG_ALARM_HOUR,
817					      rc & ~M41T80_ALHOUR_HT) < 0)
818			goto ht_err;
819	}
820
821	/* Make sure ST (stop) bit is cleared */
822	rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
823	if (rc < 0)
824		goto st_err;
825
826	if (rc & M41T80_SEC_ST) {
827		if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
828					      rc & ~M41T80_SEC_ST) < 0)
829			goto st_err;
830	}
831
832	rc = m41t80_sysfs_register(&client->dev);
833	if (rc)
834		goto exit;
835
836#ifdef CONFIG_RTC_DRV_M41T80_WDT
837	if (clientdata->features & M41T80_FEATURE_HT) {
838		save_client = client;
839		rc = misc_register(&wdt_dev);
840		if (rc)
841			goto exit;
842		rc = register_reboot_notifier(&wdt_notifier);
843		if (rc) {
844			misc_deregister(&wdt_dev);
845			goto exit;
846		}
847	}
848#endif
849	return 0;
850
851st_err:
852	rc = -EIO;
853	dev_err(&client->dev, "Can't clear ST bit\n");
854	goto exit;
855ht_err:
856	rc = -EIO;
857	dev_err(&client->dev, "Can't clear HT bit\n");
858	goto exit;
859
860exit:
861	if (rtc)
862		rtc_device_unregister(rtc);
863	kfree(clientdata);
864	return rc;
865}
866
867static int m41t80_remove(struct i2c_client *client)
868{
869	struct m41t80_data *clientdata = i2c_get_clientdata(client);
870	struct rtc_device *rtc = clientdata->rtc;
871
872#ifdef CONFIG_RTC_DRV_M41T80_WDT
873	if (clientdata->features & M41T80_FEATURE_HT) {
874		misc_deregister(&wdt_dev);
875		unregister_reboot_notifier(&wdt_notifier);
876	}
877#endif
878	if (rtc)
879		rtc_device_unregister(rtc);
880	kfree(clientdata);
881
882	return 0;
883}
884
885static struct i2c_driver m41t80_driver = {
886	.driver = {
887		.name = "rtc-m41t80",
888	},
889	.probe = m41t80_probe,
890	.remove = m41t80_remove,
891	.id_table = m41t80_id,
892};
893
894static int __init m41t80_rtc_init(void)
895{
896	return i2c_add_driver(&m41t80_driver);
897}
898
899static void __exit m41t80_rtc_exit(void)
900{
901	i2c_del_driver(&m41t80_driver);
902}
903
904MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
905MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
906MODULE_LICENSE("GPL");
907MODULE_VERSION(DRV_VERSION);
908
909module_init(m41t80_rtc_init);
910module_exit(m41t80_rtc_exit);