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
69static DEFINE_MUTEX(m41t80_rtc_mutex);
70static const struct i2c_device_id m41t80_id[] = {
71	{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
72	{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
73	{ "m41t80", M41T80_FEATURE_SQ },
74	{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
75	{ "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
76	{ "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
77	{ "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
78	{ "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
79	{ "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
80	{ "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
81	{ "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
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/*
216 * XXX - m41t80 alarm functionality is reported broken.
217 * until it is fixed, don't register alarm functions.
218 */
219static struct rtc_class_ops m41t80_rtc_ops = {
220	.read_time = m41t80_rtc_read_time,
221	.set_time = m41t80_rtc_set_time,
222	.proc = m41t80_rtc_proc,
223};
224
225#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
226static ssize_t m41t80_sysfs_show_flags(struct device *dev,
227				struct device_attribute *attr, char *buf)
228{
229	struct i2c_client *client = to_i2c_client(dev);
230	int val;
231
232	val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
233	if (val < 0)
234		return val;
235	return sprintf(buf, "%#x\n", val);
236}
237static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
238
239static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
240				struct device_attribute *attr, char *buf)
241{
242	struct i2c_client *client = to_i2c_client(dev);
243	struct m41t80_data *clientdata = i2c_get_clientdata(client);
244	int val, reg_sqw;
245
246	if (!(clientdata->features & M41T80_FEATURE_SQ))
247		return -EINVAL;
248
249	reg_sqw = M41T80_REG_SQW;
250	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
251		reg_sqw = M41T80_REG_WDAY;
252	val = i2c_smbus_read_byte_data(client, reg_sqw);
253	if (val < 0)
254		return val;
255	val = (val >> 4) & 0xf;
256	switch (val) {
257	case 0:
258		break;
259	case 1:
260		val = 32768;
261		break;
262	default:
263		val = 32768 >> val;
264	}
265	return sprintf(buf, "%d\n", val);
266}
267static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
268				struct device_attribute *attr,
269				const char *buf, size_t count)
270{
271	struct i2c_client *client = to_i2c_client(dev);
272	struct m41t80_data *clientdata = i2c_get_clientdata(client);
273	int almon, sqw, reg_sqw, rc;
274	int val = simple_strtoul(buf, NULL, 0);
275
276	if (!(clientdata->features & M41T80_FEATURE_SQ))
277		return -EINVAL;
278
279	if (val) {
280		if (!is_power_of_2(val))
281			return -EINVAL;
282		val = ilog2(val);
283		if (val == 15)
284			val = 1;
285		else if (val < 14)
286			val = 15 - val;
287		else
288			return -EINVAL;
289	}
290	/* disable SQW, set SQW frequency & re-enable */
291	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
292	if (almon < 0)
293		return almon;
294	reg_sqw = M41T80_REG_SQW;
295	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
296		reg_sqw = M41T80_REG_WDAY;
297	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
298	if (sqw < 0)
299		return sqw;
300	sqw = (sqw & 0x0f) | (val << 4);
301
302	rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
303				      almon & ~M41T80_ALMON_SQWE);
304	if (rc < 0)
305		return rc;
306
307	if (val) {
308		rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
309		if (rc < 0)
310			return rc;
311
312		rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
313					     almon | M41T80_ALMON_SQWE);
314		if (rc <0)
315			return rc;
316	}
317	return count;
318}
319static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
320		   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
321
322static struct attribute *attrs[] = {
323	&dev_attr_flags.attr,
324	&dev_attr_sqwfreq.attr,
325	NULL,
326};
327static struct attribute_group attr_group = {
328	.attrs = attrs,
329};
330
331static int m41t80_sysfs_register(struct device *dev)
332{
333	return sysfs_create_group(&dev->kobj, &attr_group);
334}
335#else
336static int m41t80_sysfs_register(struct device *dev)
337{
338	return 0;
339}
340#endif
341
342#ifdef CONFIG_RTC_DRV_M41T80_WDT
343/*
344 *****************************************************************************
345 *
346 * Watchdog Driver
347 *
348 *****************************************************************************
349 */
350static struct i2c_client *save_client;
351
352/* Default margin */
353#define WD_TIMO 60		/* 1..31 seconds */
354
355static int wdt_margin = WD_TIMO;
356module_param(wdt_margin, int, 0);
357MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
358
359static unsigned long wdt_is_open;
360static int boot_flag;
361
362/**
363 *	wdt_ping:
364 *
365 *	Reload counter one with the watchdog timeout. We don't bother reloading
366 *	the cascade counter.
367 */
368static void wdt_ping(void)
369{
370	unsigned char i2c_data[2];
371	struct i2c_msg msgs1[1] = {
372		{
373			.addr	= save_client->addr,
374			.flags	= 0,
375			.len	= 2,
376			.buf	= i2c_data,
377		},
378	};
379	struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
380
381	i2c_data[0] = 0x09;		/* watchdog register */
382
383	if (wdt_margin > 31)
384		i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
385	else
386		/*
387		 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
388		 */
389		i2c_data[1] = wdt_margin<<2 | 0x82;
390
391	/*
392	 * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
393	 * that would be an invalid resolution.
394	 */
395	if (clientdata->features & M41T80_FEATURE_WD)
396		i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
397
398	i2c_transfer(save_client->adapter, msgs1, 1);
399}
400
401/**
402 *	wdt_disable:
403 *
404 *	disables watchdog.
405 */
406static void wdt_disable(void)
407{
408	unsigned char i2c_data[2], i2c_buf[0x10];
409	struct i2c_msg msgs0[2] = {
410		{
411			.addr	= save_client->addr,
412			.flags	= 0,
413			.len	= 1,
414			.buf	= i2c_data,
415		},
416		{
417			.addr	= save_client->addr,
418			.flags	= I2C_M_RD,
419			.len	= 1,
420			.buf	= i2c_buf,
421		},
422	};
423	struct i2c_msg msgs1[1] = {
424		{
425			.addr	= save_client->addr,
426			.flags	= 0,
427			.len	= 2,
428			.buf	= i2c_data,
429		},
430	};
431
432	i2c_data[0] = 0x09;
433	i2c_transfer(save_client->adapter, msgs0, 2);
434
435	i2c_data[0] = 0x09;
436	i2c_data[1] = 0x00;
437	i2c_transfer(save_client->adapter, msgs1, 1);
438}
439
440/**
441 *	wdt_write:
442 *	@file: file handle to the watchdog
443 *	@buf: buffer to write (unused as data does not matter here
444 *	@count: count of bytes
445 *	@ppos: pointer to the position to write. No seeks allowed
446 *
447 *	A write to a watchdog device is defined as a keepalive signal. Any
448 *	write of data will do, as we we don't define content meaning.
449 */
450static ssize_t wdt_write(struct file *file, const char __user *buf,
451			 size_t count, loff_t *ppos)
452{
453	if (count) {
454		wdt_ping();
455		return 1;
456	}
457	return 0;
458}
459
460static ssize_t wdt_read(struct file *file, char __user *buf,
461			size_t count, loff_t *ppos)
462{
463	return 0;
464}
465
466/**
467 *	wdt_ioctl:
468 *	@inode: inode of the device
469 *	@file: file handle to the device
470 *	@cmd: watchdog command
471 *	@arg: argument pointer
472 *
473 *	The watchdog API defines a common set of functions for all watchdogs
474 *	according to their available features. We only actually usefully support
475 *	querying capabilities and current status.
476 */
477static int wdt_ioctl(struct file *file, unsigned int cmd,
478		     unsigned long arg)
479{
480	int new_margin, rv;
481	static struct watchdog_info ident = {
482		.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
483			WDIOF_SETTIMEOUT,
484		.firmware_version = 1,
485		.identity = "M41T80 WTD"
486	};
487
488	switch (cmd) {
489	case WDIOC_GETSUPPORT:
490		return copy_to_user((struct watchdog_info __user *)arg, &ident,
491				    sizeof(ident)) ? -EFAULT : 0;
492
493	case WDIOC_GETSTATUS:
494	case WDIOC_GETBOOTSTATUS:
495		return put_user(boot_flag, (int __user *)arg);
496	case WDIOC_KEEPALIVE:
497		wdt_ping();
498		return 0;
499	case WDIOC_SETTIMEOUT:
500		if (get_user(new_margin, (int __user *)arg))
501			return -EFAULT;
502		/* Arbitrary, can't find the card's limits */
503		if (new_margin < 1 || new_margin > 124)
504			return -EINVAL;
505		wdt_margin = new_margin;
506		wdt_ping();
507		/* Fall */
508	case WDIOC_GETTIMEOUT:
509		return put_user(wdt_margin, (int __user *)arg);
510
511	case WDIOC_SETOPTIONS:
512		if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
513			return -EFAULT;
514
515		if (rv & WDIOS_DISABLECARD) {
516			pr_info("rtc-m41t80: disable watchdog\n");
517			wdt_disable();
518		}
519
520		if (rv & WDIOS_ENABLECARD) {
521			pr_info("rtc-m41t80: enable watchdog\n");
522			wdt_ping();
523		}
524
525		return -EINVAL;
526	}
527	return -ENOTTY;
528}
529
530static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
531			       unsigned long arg)
532{
533	int ret;
534
535	mutex_lock(&m41t80_rtc_mutex);
536	ret = wdt_ioctl(file, cmd, arg);
537	mutex_unlock(&m41t80_rtc_mutex);
538
539	return ret;
540}
541
542/**
543 *	wdt_open:
544 *	@inode: inode of device
545 *	@file: file handle to device
546 *
547 */
548static int wdt_open(struct inode *inode, struct file *file)
549{
550	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
551		mutex_lock(&m41t80_rtc_mutex);
552		if (test_and_set_bit(0, &wdt_is_open)) {
553			mutex_unlock(&m41t80_rtc_mutex);
554			return -EBUSY;
555		}
556		/*
557		 *	Activate
558		 */
559		wdt_is_open = 1;
560		mutex_unlock(&m41t80_rtc_mutex);
561		return nonseekable_open(inode, file);
562	}
563	return -ENODEV;
564}
565
566/**
567 *	wdt_close:
568 *	@inode: inode to board
569 *	@file: file handle to board
570 *
571 */
572static int wdt_release(struct inode *inode, struct file *file)
573{
574	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
575		clear_bit(0, &wdt_is_open);
576	return 0;
577}
578
579/**
580 *	notify_sys:
581 *	@this: our notifier block
582 *	@code: the event being reported
583 *	@unused: unused
584 *
585 *	Our notifier is called on system shutdowns. We want to turn the card
586 *	off at reboot otherwise the machine will reboot again during memory
587 *	test or worse yet during the following fsck. This would suck, in fact
588 *	trust me - if it happens it does suck.
589 */
590static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
591			  void *unused)
592{
593	if (code == SYS_DOWN || code == SYS_HALT)
594		/* Disable Watchdog */
595		wdt_disable();
596	return NOTIFY_DONE;
597}
598
599static const struct file_operations wdt_fops = {
600	.owner	= THIS_MODULE,
601	.read	= wdt_read,
602	.unlocked_ioctl = wdt_unlocked_ioctl,
603	.write	= wdt_write,
604	.open	= wdt_open,
605	.release = wdt_release,
606	.llseek = no_llseek,
607};
608
609static struct miscdevice wdt_dev = {
610	.minor = WATCHDOG_MINOR,
611	.name = "watchdog",
612	.fops = &wdt_fops,
613};
614
615/*
616 *	The WDT card needs to learn about soft shutdowns in order to
617 *	turn the timebomb registers off.
618 */
619static struct notifier_block wdt_notifier = {
620	.notifier_call = wdt_notify_sys,
621};
622#endif /* CONFIG_RTC_DRV_M41T80_WDT */
623
624/*
625 *****************************************************************************
626 *
627 *	Driver Interface
628 *
629 *****************************************************************************
630 */
631static int m41t80_probe(struct i2c_client *client,
632			const struct i2c_device_id *id)
633{
634	int rc = 0;
635	struct rtc_device *rtc = NULL;
636	struct rtc_time tm;
637	struct m41t80_data *clientdata = NULL;
638
639	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
640				     | I2C_FUNC_SMBUS_BYTE_DATA))
641		return -ENODEV;
642
643	clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
644				GFP_KERNEL);
645	if (!clientdata)
646		return -ENOMEM;
647
648	clientdata->features = id->driver_data;
649	i2c_set_clientdata(client, clientdata);
650
651	rtc = devm_rtc_device_register(&client->dev, client->name,
652					&m41t80_rtc_ops, THIS_MODULE);
653	if (IS_ERR(rtc))
654		return PTR_ERR(rtc);
655
656	clientdata->rtc = rtc;
657
658	/* Make sure HT (Halt Update) bit is cleared */
659	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
660
661	if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
662		if (clientdata->features & M41T80_FEATURE_HT) {
663			m41t80_get_datetime(client, &tm);
664			dev_info(&client->dev, "HT bit was set!\n");
665			dev_info(&client->dev,
666				 "Power Down at "
667				 "%04i-%02i-%02i %02i:%02i:%02i\n",
668				 tm.tm_year + 1900,
669				 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
670				 tm.tm_min, tm.tm_sec);
671		}
672		rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
673					      rc & ~M41T80_ALHOUR_HT);
674	}
675
676	if (rc < 0) {
677		dev_err(&client->dev, "Can't clear HT bit\n");
678		return rc;
679	}
680
681	/* Make sure ST (stop) bit is cleared */
682	rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
683
684	if (rc >= 0 && rc & M41T80_SEC_ST)
685		rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
686					      rc & ~M41T80_SEC_ST);
687	if (rc < 0) {
688		dev_err(&client->dev, "Can't clear ST bit\n");
689		return rc;
690	}
691
692	rc = m41t80_sysfs_register(&client->dev);
693	if (rc)
694		return rc;
695
696#ifdef CONFIG_RTC_DRV_M41T80_WDT
697	if (clientdata->features & M41T80_FEATURE_HT) {
698		save_client = client;
699		rc = misc_register(&wdt_dev);
700		if (rc)
701			return rc;
702		rc = register_reboot_notifier(&wdt_notifier);
703		if (rc) {
704			misc_deregister(&wdt_dev);
705			return rc;
706		}
707	}
708#endif
709	return 0;
710}
711
712static int m41t80_remove(struct i2c_client *client)
713{
714#ifdef CONFIG_RTC_DRV_M41T80_WDT
715	struct m41t80_data *clientdata = i2c_get_clientdata(client);
716
717	if (clientdata->features & M41T80_FEATURE_HT) {
718		misc_deregister(&wdt_dev);
719		unregister_reboot_notifier(&wdt_notifier);
720	}
721#endif
722
723	return 0;
724}
725
726static struct i2c_driver m41t80_driver = {
727	.driver = {
728		.name = "rtc-m41t80",
729	},
730	.probe = m41t80_probe,
731	.remove = m41t80_remove,
732	.id_table = m41t80_id,
733};
734
735module_i2c_driver(m41t80_driver);
736
737MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
738MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
739MODULE_LICENSE("GPL");
740