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
216/*
217 * XXX - m41t80 alarm functionality is reported broken.
218 * until it is fixed, don't register alarm functions.
219 */
220static struct rtc_class_ops m41t80_rtc_ops = {
221	.read_time = m41t80_rtc_read_time,
222	.set_time = m41t80_rtc_set_time,
223	.proc = m41t80_rtc_proc,
224};
225
226#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
227static ssize_t m41t80_sysfs_show_flags(struct device *dev,
228				struct device_attribute *attr, char *buf)
229{
230	struct i2c_client *client = to_i2c_client(dev);
231	int val;
232
233	val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
234	if (val < 0)
235		return -EIO;
236	return sprintf(buf, "%#x\n", val);
237}
238static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
239
240static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
241				struct device_attribute *attr, char *buf)
242{
243	struct i2c_client *client = to_i2c_client(dev);
244	struct m41t80_data *clientdata = i2c_get_clientdata(client);
245	int val, reg_sqw;
246
247	if (!(clientdata->features & M41T80_FEATURE_SQ))
248		return -EINVAL;
249
250	reg_sqw = M41T80_REG_SQW;
251	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
252		reg_sqw = M41T80_REG_WDAY;
253	val = i2c_smbus_read_byte_data(client, reg_sqw);
254	if (val < 0)
255		return -EIO;
256	val = (val >> 4) & 0xf;
257	switch (val) {
258	case 0:
259		break;
260	case 1:
261		val = 32768;
262		break;
263	default:
264		val = 32768 >> val;
265	}
266	return sprintf(buf, "%d\n", val);
267}
268static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
269				struct device_attribute *attr,
270				const char *buf, size_t count)
271{
272	struct i2c_client *client = to_i2c_client(dev);
273	struct m41t80_data *clientdata = i2c_get_clientdata(client);
274	int almon, sqw, reg_sqw;
275	int val = simple_strtoul(buf, NULL, 0);
276
277	if (!(clientdata->features & M41T80_FEATURE_SQ))
278		return -EINVAL;
279
280	if (val) {
281		if (!is_power_of_2(val))
282			return -EINVAL;
283		val = ilog2(val);
284		if (val == 15)
285			val = 1;
286		else if (val < 14)
287			val = 15 - val;
288		else
289			return -EINVAL;
290	}
291	/* disable SQW, set SQW frequency & re-enable */
292	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
293	if (almon < 0)
294		return -EIO;
295	reg_sqw = M41T80_REG_SQW;
296	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
297		reg_sqw = M41T80_REG_WDAY;
298	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
299	if (sqw < 0)
300		return -EIO;
301	sqw = (sqw & 0x0f) | (val << 4);
302	if (i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
303				      almon & ~M41T80_ALMON_SQWE) < 0 ||
304	    i2c_smbus_write_byte_data(client, reg_sqw, sqw) < 0)
305		return -EIO;
306	if (val && i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
307					     almon | M41T80_ALMON_SQWE) < 0)
308		return -EIO;
309	return count;
310}
311static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
312		   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
313
314static struct attribute *attrs[] = {
315	&dev_attr_flags.attr,
316	&dev_attr_sqwfreq.attr,
317	NULL,
318};
319static struct attribute_group attr_group = {
320	.attrs = attrs,
321};
322
323static int m41t80_sysfs_register(struct device *dev)
324{
325	return sysfs_create_group(&dev->kobj, &attr_group);
326}
327#else
328static int m41t80_sysfs_register(struct device *dev)
329{
330	return 0;
331}
332#endif
333
334#ifdef CONFIG_RTC_DRV_M41T80_WDT
335/*
336 *****************************************************************************
337 *
338 * Watchdog Driver
339 *
340 *****************************************************************************
341 */
342static struct i2c_client *save_client;
343
344/* Default margin */
345#define WD_TIMO 60		/* 1..31 seconds */
346
347static int wdt_margin = WD_TIMO;
348module_param(wdt_margin, int, 0);
349MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
350
351static unsigned long wdt_is_open;
352static int boot_flag;
353
354/**
355 *	wdt_ping:
356 *
357 *	Reload counter one with the watchdog timeout. We don't bother reloading
358 *	the cascade counter.
359 */
360static void wdt_ping(void)
361{
362	unsigned char i2c_data[2];
363	struct i2c_msg msgs1[1] = {
364		{
365			.addr	= save_client->addr,
366			.flags	= 0,
367			.len	= 2,
368			.buf	= i2c_data,
369		},
370	};
371	struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
372
373	i2c_data[0] = 0x09;		/* watchdog register */
374
375	if (wdt_margin > 31)
376		i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
377	else
378		/*
379		 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
380		 */
381		i2c_data[1] = wdt_margin<<2 | 0x82;
382
383	/*
384	 * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
385	 * that would be an invalid resolution.
386	 */
387	if (clientdata->features & M41T80_FEATURE_WD)
388		i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
389
390	i2c_transfer(save_client->adapter, msgs1, 1);
391}
392
393/**
394 *	wdt_disable:
395 *
396 *	disables watchdog.
397 */
398static void wdt_disable(void)
399{
400	unsigned char i2c_data[2], i2c_buf[0x10];
401	struct i2c_msg msgs0[2] = {
402		{
403			.addr	= save_client->addr,
404			.flags	= 0,
405			.len	= 1,
406			.buf	= i2c_data,
407		},
408		{
409			.addr	= save_client->addr,
410			.flags	= I2C_M_RD,
411			.len	= 1,
412			.buf	= i2c_buf,
413		},
414	};
415	struct i2c_msg msgs1[1] = {
416		{
417			.addr	= save_client->addr,
418			.flags	= 0,
419			.len	= 2,
420			.buf	= i2c_data,
421		},
422	};
423
424	i2c_data[0] = 0x09;
425	i2c_transfer(save_client->adapter, msgs0, 2);
426
427	i2c_data[0] = 0x09;
428	i2c_data[1] = 0x00;
429	i2c_transfer(save_client->adapter, msgs1, 1);
430}
431
432/**
433 *	wdt_write:
434 *	@file: file handle to the watchdog
435 *	@buf: buffer to write (unused as data does not matter here
436 *	@count: count of bytes
437 *	@ppos: pointer to the position to write. No seeks allowed
438 *
439 *	A write to a watchdog device is defined as a keepalive signal. Any
440 *	write of data will do, as we we don't define content meaning.
441 */
442static ssize_t wdt_write(struct file *file, const char __user *buf,
443			 size_t count, loff_t *ppos)
444{
445	if (count) {
446		wdt_ping();
447		return 1;
448	}
449	return 0;
450}
451
452static ssize_t wdt_read(struct file *file, char __user *buf,
453			size_t count, loff_t *ppos)
454{
455	return 0;
456}
457
458/**
459 *	wdt_ioctl:
460 *	@inode: inode of the device
461 *	@file: file handle to the device
462 *	@cmd: watchdog command
463 *	@arg: argument pointer
464 *
465 *	The watchdog API defines a common set of functions for all watchdogs
466 *	according to their available features. We only actually usefully support
467 *	querying capabilities and current status.
468 */
469static int wdt_ioctl(struct file *file, unsigned int cmd,
470		     unsigned long arg)
471{
472	int new_margin, rv;
473	static struct watchdog_info ident = {
474		.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
475			WDIOF_SETTIMEOUT,
476		.firmware_version = 1,
477		.identity = "M41T80 WTD"
478	};
479
480	switch (cmd) {
481	case WDIOC_GETSUPPORT:
482		return copy_to_user((struct watchdog_info __user *)arg, &ident,
483				    sizeof(ident)) ? -EFAULT : 0;
484
485	case WDIOC_GETSTATUS:
486	case WDIOC_GETBOOTSTATUS:
487		return put_user(boot_flag, (int __user *)arg);
488	case WDIOC_KEEPALIVE:
489		wdt_ping();
490		return 0;
491	case WDIOC_SETTIMEOUT:
492		if (get_user(new_margin, (int __user *)arg))
493			return -EFAULT;
494		/* Arbitrary, can't find the card's limits */
495		if (new_margin < 1 || new_margin > 124)
496			return -EINVAL;
497		wdt_margin = new_margin;
498		wdt_ping();
499		/* Fall */
500	case WDIOC_GETTIMEOUT:
501		return put_user(wdt_margin, (int __user *)arg);
502
503	case WDIOC_SETOPTIONS:
504		if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
505			return -EFAULT;
506
507		if (rv & WDIOS_DISABLECARD) {
508			pr_info("rtc-m41t80: disable watchdog\n");
509			wdt_disable();
510		}
511
512		if (rv & WDIOS_ENABLECARD) {
513			pr_info("rtc-m41t80: enable watchdog\n");
514			wdt_ping();
515		}
516
517		return -EINVAL;
518	}
519	return -ENOTTY;
520}
521
522static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
523			       unsigned long arg)
524{
525	int ret;
526
527	mutex_lock(&m41t80_rtc_mutex);
528	ret = wdt_ioctl(file, cmd, arg);
529	mutex_unlock(&m41t80_rtc_mutex);
530
531	return ret;
532}
533
534/**
535 *	wdt_open:
536 *	@inode: inode of device
537 *	@file: file handle to device
538 *
539 */
540static int wdt_open(struct inode *inode, struct file *file)
541{
542	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
543		mutex_lock(&m41t80_rtc_mutex);
544		if (test_and_set_bit(0, &wdt_is_open)) {
545			mutex_unlock(&m41t80_rtc_mutex);
546			return -EBUSY;
547		}
548		/*
549		 *	Activate
550		 */
551		wdt_is_open = 1;
552		mutex_unlock(&m41t80_rtc_mutex);
553		return nonseekable_open(inode, file);
554	}
555	return -ENODEV;
556}
557
558/**
559 *	wdt_close:
560 *	@inode: inode to board
561 *	@file: file handle to board
562 *
563 */
564static int wdt_release(struct inode *inode, struct file *file)
565{
566	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
567		clear_bit(0, &wdt_is_open);
568	return 0;
569}
570
571/**
572 *	notify_sys:
573 *	@this: our notifier block
574 *	@code: the event being reported
575 *	@unused: unused
576 *
577 *	Our notifier is called on system shutdowns. We want to turn the card
578 *	off at reboot otherwise the machine will reboot again during memory
579 *	test or worse yet during the following fsck. This would suck, in fact
580 *	trust me - if it happens it does suck.
581 */
582static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
583			  void *unused)
584{
585	if (code == SYS_DOWN || code == SYS_HALT)
586		/* Disable Watchdog */
587		wdt_disable();
588	return NOTIFY_DONE;
589}
590
591static const struct file_operations wdt_fops = {
592	.owner	= THIS_MODULE,
593	.read	= wdt_read,
594	.unlocked_ioctl = wdt_unlocked_ioctl,
595	.write	= wdt_write,
596	.open	= wdt_open,
597	.release = wdt_release,
598	.llseek = no_llseek,
599};
600
601static struct miscdevice wdt_dev = {
602	.minor = WATCHDOG_MINOR,
603	.name = "watchdog",
604	.fops = &wdt_fops,
605};
606
607/*
608 *	The WDT card needs to learn about soft shutdowns in order to
609 *	turn the timebomb registers off.
610 */
611static struct notifier_block wdt_notifier = {
612	.notifier_call = wdt_notify_sys,
613};
614#endif /* CONFIG_RTC_DRV_M41T80_WDT */
615
616/*
617 *****************************************************************************
618 *
619 *	Driver Interface
620 *
621 *****************************************************************************
622 */
623static int m41t80_probe(struct i2c_client *client,
624			const struct i2c_device_id *id)
625{
626	int rc = 0;
627	struct rtc_device *rtc = NULL;
628	struct rtc_time tm;
629	struct m41t80_data *clientdata = NULL;
630
631	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
632				     | I2C_FUNC_SMBUS_BYTE_DATA)) {
633		rc = -ENODEV;
634		goto exit;
635	}
636
637	dev_info(&client->dev,
638		 "chip found, driver version " DRV_VERSION "\n");
639
640	clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
641				GFP_KERNEL);
642	if (!clientdata) {
643		rc = -ENOMEM;
644		goto exit;
645	}
646
647	clientdata->features = id->driver_data;
648	i2c_set_clientdata(client, clientdata);
649
650	rtc = devm_rtc_device_register(&client->dev, client->name,
651					&m41t80_rtc_ops, THIS_MODULE);
652	if (IS_ERR(rtc)) {
653		rc = PTR_ERR(rtc);
654		rtc = NULL;
655		goto exit;
656	}
657
658	clientdata->rtc = rtc;
659
660	/* Make sure HT (Halt Update) bit is cleared */
661	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
662	if (rc < 0)
663		goto ht_err;
664
665	if (rc & M41T80_ALHOUR_HT) {
666		if (clientdata->features & M41T80_FEATURE_HT) {
667			m41t80_get_datetime(client, &tm);
668			dev_info(&client->dev, "HT bit was set!\n");
669			dev_info(&client->dev,
670				 "Power Down at "
671				 "%04i-%02i-%02i %02i:%02i:%02i\n",
672				 tm.tm_year + 1900,
673				 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
674				 tm.tm_min, tm.tm_sec);
675		}
676		if (i2c_smbus_write_byte_data(client,
677					      M41T80_REG_ALARM_HOUR,
678					      rc & ~M41T80_ALHOUR_HT) < 0)
679			goto ht_err;
680	}
681
682	/* Make sure ST (stop) bit is cleared */
683	rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
684	if (rc < 0)
685		goto st_err;
686
687	if (rc & M41T80_SEC_ST) {
688		if (i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
689					      rc & ~M41T80_SEC_ST) < 0)
690			goto st_err;
691	}
692
693	rc = m41t80_sysfs_register(&client->dev);
694	if (rc)
695		goto exit;
696
697#ifdef CONFIG_RTC_DRV_M41T80_WDT
698	if (clientdata->features & M41T80_FEATURE_HT) {
699		save_client = client;
700		rc = misc_register(&wdt_dev);
701		if (rc)
702			goto exit;
703		rc = register_reboot_notifier(&wdt_notifier);
704		if (rc) {
705			misc_deregister(&wdt_dev);
706			goto exit;
707		}
708	}
709#endif
710	return 0;
711
712st_err:
713	rc = -EIO;
714	dev_err(&client->dev, "Can't clear ST bit\n");
715	goto exit;
716ht_err:
717	rc = -EIO;
718	dev_err(&client->dev, "Can't clear HT bit\n");
719	goto exit;
720
721exit:
722	return rc;
723}
724
725static int m41t80_remove(struct i2c_client *client)
726{
727#ifdef CONFIG_RTC_DRV_M41T80_WDT
728	struct m41t80_data *clientdata = i2c_get_clientdata(client);
729
730	if (clientdata->features & M41T80_FEATURE_HT) {
731		misc_deregister(&wdt_dev);
732		unregister_reboot_notifier(&wdt_notifier);
733	}
734#endif
735
736	return 0;
737}
738
739static struct i2c_driver m41t80_driver = {
740	.driver = {
741		.name = "rtc-m41t80",
742	},
743	.probe = m41t80_probe,
744	.remove = m41t80_remove,
745	.id_table = m41t80_id,
746};
747
748module_i2c_driver(m41t80_driver);
749
750MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
751MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
752MODULE_LICENSE("GPL");
753MODULE_VERSION(DRV_VERSION);