Initial import

1 files changed, 741 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c
new file mode 100644
index 000000000..a82937e2f
--- /dev/null
+++ b/drivers/rtc/rtc-m41t80.c
@@ -0,0 +1,741 @@
+/*
+ * I2C client/driver for the ST M41T80 family of i2c rtc chips.
+ *
+ * Author: Alexander Bigga <ab@mycable.de>
+ *
+ * Based on m41t00.c by Mark A. Greer <mgreer@mvista.com>
+ *
+ * 2006 (c) mycable GmbH
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bcd.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/string.h>
+#ifdef CONFIG_RTC_DRV_M41T80_WDT
+#include <linux/fs.h>
+#include <linux/ioctl.h>
+#include <linux/miscdevice.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+#endif
+
+#define M41T80_REG_SSEC	0
+#define M41T80_REG_SEC	1
+#define M41T80_REG_MIN	2
+#define M41T80_REG_HOUR	3
+#define M41T80_REG_WDAY	4
+#define M41T80_REG_DAY	5
+#define M41T80_REG_MON	6
+#define M41T80_REG_YEAR	7
+#define M41T80_REG_ALARM_MON	0xa
+#define M41T80_REG_ALARM_DAY	0xb
+#define M41T80_REG_ALARM_HOUR	0xc
+#define M41T80_REG_ALARM_MIN	0xd
+#define M41T80_REG_ALARM_SEC	0xe
+#define M41T80_REG_FLAGS	0xf
+#define M41T80_REG_SQW	0x13
+
+#define M41T80_DATETIME_REG_SIZE	(M41T80_REG_YEAR + 1)
+#define M41T80_ALARM_REG_SIZE	\
+	(M41T80_REG_ALARM_SEC + 1 - M41T80_REG_ALARM_MON)
+
+#define M41T80_SEC_ST		(1 << 7)	/* ST: Stop Bit */
+#define M41T80_ALMON_AFE	(1 << 7)	/* AFE: AF Enable Bit */
+#define M41T80_ALMON_SQWE	(1 << 6)	/* SQWE: SQW Enable Bit */
+#define M41T80_ALHOUR_HT	(1 << 6)	/* HT: Halt Update Bit */
+#define M41T80_FLAGS_AF		(1 << 6)	/* AF: Alarm Flag Bit */
+#define M41T80_FLAGS_BATT_LOW	(1 << 4)	/* BL: Battery Low Bit */
+#define M41T80_WATCHDOG_RB2	(1 << 7)	/* RB: Watchdog resolution */
+#define M41T80_WATCHDOG_RB1	(1 << 1)	/* RB: Watchdog resolution */
+#define M41T80_WATCHDOG_RB0	(1 << 0)	/* RB: Watchdog resolution */
+
+#define M41T80_FEATURE_HT	(1 << 0)	/* Halt feature */
+#define M41T80_FEATURE_BL	(1 << 1)	/* Battery low indicator */
+#define M41T80_FEATURE_SQ	(1 << 2)	/* Squarewave feature */
+#define M41T80_FEATURE_WD	(1 << 3)	/* Extra watchdog resolution */
+#define M41T80_FEATURE_SQ_ALT	(1 << 4)	/* RSx bits are in reg 4 */
+
+static DEFINE_MUTEX(m41t80_rtc_mutex);
+static const struct i2c_device_id m41t80_id[] = {
+	{ "m41t62", M41T80_FEATURE_SQ | M41T80_FEATURE_SQ_ALT },
+	{ "m41t65", M41T80_FEATURE_HT | M41T80_FEATURE_WD },
+	{ "m41t80", M41T80_FEATURE_SQ },
+	{ "m41t81", M41T80_FEATURE_HT | M41T80_FEATURE_SQ},
+	{ "m41t81s", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "m41t82", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "m41t83", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "m41st84", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "m41st85", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "m41st87", M41T80_FEATURE_HT | M41T80_FEATURE_BL | M41T80_FEATURE_SQ },
+	{ "rv4162", M41T80_FEATURE_SQ | M41T80_FEATURE_WD | M41T80_FEATURE_SQ_ALT },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, m41t80_id);
+
+struct m41t80_data {
+	u8 features;
+	struct rtc_device *rtc;
+};
+
+static int m41t80_get_datetime(struct i2c_client *client,
+			       struct rtc_time *tm)
+{
+	u8 buf[M41T80_DATETIME_REG_SIZE], dt_addr[1] = { M41T80_REG_SEC };
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= dt_addr,
+		},
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
+			.buf	= buf + M41T80_REG_SEC,
+		},
+	};
+
+	if (i2c_transfer(client->adapter, msgs, 2) < 0) {
+		dev_err(&client->dev, "read error\n");
+		return -EIO;
+	}
+
+	tm->tm_sec = bcd2bin(buf[M41T80_REG_SEC] & 0x7f);
+	tm->tm_min = bcd2bin(buf[M41T80_REG_MIN] & 0x7f);
+	tm->tm_hour = bcd2bin(buf[M41T80_REG_HOUR] & 0x3f);
+	tm->tm_mday = bcd2bin(buf[M41T80_REG_DAY] & 0x3f);
+	tm->tm_wday = buf[M41T80_REG_WDAY] & 0x07;
+	tm->tm_mon = bcd2bin(buf[M41T80_REG_MON] & 0x1f) - 1;
+
+	/* assume 20YY not 19YY, and ignore the Century Bit */
+	tm->tm_year = bcd2bin(buf[M41T80_REG_YEAR]) + 100;
+	return rtc_valid_tm(tm);
+}
+
+/* Sets the given date and time to the real time clock. */
+static int m41t80_set_datetime(struct i2c_client *client, struct rtc_time *tm)
+{
+	u8 wbuf[1 + M41T80_DATETIME_REG_SIZE];
+	u8 *buf = &wbuf[1];
+	u8 dt_addr[1] = { M41T80_REG_SEC };
+	struct i2c_msg msgs_in[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= dt_addr,
+		},
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= M41T80_DATETIME_REG_SIZE - M41T80_REG_SEC,
+			.buf	= buf + M41T80_REG_SEC,
+		},
+	};
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags	= 0,
+			.len	= 1 + M41T80_DATETIME_REG_SIZE,
+			.buf	= wbuf,
+		 },
+	};
+
+	/* Read current reg values into buf[1..7] */
+	if (i2c_transfer(client->adapter, msgs_in, 2) < 0) {
+		dev_err(&client->dev, "read error\n");
+		return -EIO;
+	}
+
+	wbuf[0] = 0; /* offset into rtc's regs */
+	/* Merge time-data and register flags into buf[0..7] */
+	buf[M41T80_REG_SSEC] = 0;
+	buf[M41T80_REG_SEC] =
+		bin2bcd(tm->tm_sec) | (buf[M41T80_REG_SEC] & ~0x7f);
+	buf[M41T80_REG_MIN] =
+		bin2bcd(tm->tm_min) | (buf[M41T80_REG_MIN] & ~0x7f);
+	buf[M41T80_REG_HOUR] =
+		bin2bcd(tm->tm_hour) | (buf[M41T80_REG_HOUR] & ~0x3f);
+	buf[M41T80_REG_WDAY] =
+		(tm->tm_wday & 0x07) | (buf[M41T80_REG_WDAY] & ~0x07);
+	buf[M41T80_REG_DAY] =
+		bin2bcd(tm->tm_mday) | (buf[M41T80_REG_DAY] & ~0x3f);
+	buf[M41T80_REG_MON] =
+		bin2bcd(tm->tm_mon + 1) | (buf[M41T80_REG_MON] & ~0x1f);
+	/* assume 20YY not 19YY */
+	buf[M41T80_REG_YEAR] = bin2bcd(tm->tm_year % 100);
+
+	if (i2c_transfer(client->adapter, msgs, 1) != 1) {
+		dev_err(&client->dev, "write error\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
+static int m41t80_rtc_proc(struct device *dev, struct seq_file *seq)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct m41t80_data *clientdata = i2c_get_clientdata(client);
+	u8 reg;
+
+	if (clientdata->features & M41T80_FEATURE_BL) {
+		reg = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
+		seq_printf(seq, "battery\t\t: %s\n",
+			   (reg & M41T80_FLAGS_BATT_LOW) ? "exhausted" : "ok");
+	}
+	return 0;
+}
+#else
+#define m41t80_rtc_proc NULL
+#endif
+
+static int m41t80_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	return m41t80_get_datetime(to_i2c_client(dev), tm);
+}
+
+static int m41t80_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	return m41t80_set_datetime(to_i2c_client(dev), tm);
+}
+
+/*
+ * XXX - m41t80 alarm functionality is reported broken.
+ * until it is fixed, don't register alarm functions.
+ */
+static struct rtc_class_ops m41t80_rtc_ops = {
+	.read_time = m41t80_rtc_read_time,
+	.set_time = m41t80_rtc_set_time,
+	.proc = m41t80_rtc_proc,
+};
+
+#if defined(CONFIG_RTC_INTF_SYSFS) || defined(CONFIG_RTC_INTF_SYSFS_MODULE)
+static ssize_t m41t80_sysfs_show_flags(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int val;
+
+	val = i2c_smbus_read_byte_data(client, M41T80_REG_FLAGS);
+	if (val < 0)
+		return val;
+	return sprintf(buf, "%#x\n", val);
+}
+static DEVICE_ATTR(flags, S_IRUGO, m41t80_sysfs_show_flags, NULL);
+
+static ssize_t m41t80_sysfs_show_sqwfreq(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct m41t80_data *clientdata = i2c_get_clientdata(client);
+	int val, reg_sqw;
+
+	if (!(clientdata->features & M41T80_FEATURE_SQ))
+		return -EINVAL;
+
+	reg_sqw = M41T80_REG_SQW;
+	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
+		reg_sqw = M41T80_REG_WDAY;
+	val = i2c_smbus_read_byte_data(client, reg_sqw);
+	if (val < 0)
+		return val;
+	val = (val >> 4) & 0xf;
+	switch (val) {
+	case 0:
+		break;
+	case 1:
+		val = 32768;
+		break;
+	default:
+		val = 32768 >> val;
+	}
+	return sprintf(buf, "%d\n", val);
+}
+static ssize_t m41t80_sysfs_set_sqwfreq(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct m41t80_data *clientdata = i2c_get_clientdata(client);
+	int almon, sqw, reg_sqw, rc;
+	int val = simple_strtoul(buf, NULL, 0);
+
+	if (!(clientdata->features & M41T80_FEATURE_SQ))
+		return -EINVAL;
+
+	if (val) {
+		if (!is_power_of_2(val))
+			return -EINVAL;
+		val = ilog2(val);
+		if (val == 15)
+			val = 1;
+		else if (val < 14)
+			val = 15 - val;
+		else
+			return -EINVAL;
+	}
+	/* disable SQW, set SQW frequency & re-enable */
+	almon = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON);
+	if (almon < 0)
+		return almon;
+	reg_sqw = M41T80_REG_SQW;
+	if (clientdata->features & M41T80_FEATURE_SQ_ALT)
+		reg_sqw = M41T80_REG_WDAY;
+	sqw = i2c_smbus_read_byte_data(client, reg_sqw);
+	if (sqw < 0)
+		return sqw;
+	sqw = (sqw & 0x0f) | (val << 4);
+
+	rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
+				      almon & ~M41T80_ALMON_SQWE);
+	if (rc < 0)
+		return rc;
+
+	if (val) {
+		rc = i2c_smbus_write_byte_data(client, reg_sqw, sqw);
+		if (rc < 0)
+			return rc;
+
+		rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON,
+					     almon | M41T80_ALMON_SQWE);
+		if (rc <0)
+			return rc;
+	}
+	return count;
+}
+static DEVICE_ATTR(sqwfreq, S_IRUGO | S_IWUSR,
+		   m41t80_sysfs_show_sqwfreq, m41t80_sysfs_set_sqwfreq);
+
+static struct attribute *attrs[] = {
+	&dev_attr_flags.attr,
+	&dev_attr_sqwfreq.attr,
+	NULL,
+};
+static struct attribute_group attr_group = {
+	.attrs = attrs,
+};
+
+static int m41t80_sysfs_register(struct device *dev)
+{
+	return sysfs_create_group(&dev->kobj, &attr_group);
+}
+#else
+static int m41t80_sysfs_register(struct device *dev)
+{
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_RTC_DRV_M41T80_WDT
+/*
+ *****************************************************************************
+ *
+ * Watchdog Driver
+ *
+ *****************************************************************************
+ */
+static struct i2c_client *save_client;
+
+/* Default margin */
+#define WD_TIMO 60		/* 1..31 seconds */
+
+static int wdt_margin = WD_TIMO;
+module_param(wdt_margin, int, 0);
+MODULE_PARM_DESC(wdt_margin, "Watchdog timeout in seconds (default 60s)");
+
+static unsigned long wdt_is_open;
+static int boot_flag;
+
+/**
+ *	wdt_ping:
+ *
+ *	Reload counter one with the watchdog timeout. We don't bother reloading
+ *	the cascade counter.
+ */
+static void wdt_ping(void)
+{
+	unsigned char i2c_data[2];
+	struct i2c_msg msgs1[1] = {
+		{
+			.addr	= save_client->addr,
+			.flags	= 0,
+			.len	= 2,
+			.buf	= i2c_data,
+		},
+	};
+	struct m41t80_data *clientdata = i2c_get_clientdata(save_client);
+
+	i2c_data[0] = 0x09;		/* watchdog register */
+
+	if (wdt_margin > 31)
+		i2c_data[1] = (wdt_margin & 0xFC) | 0x83; /* resolution = 4s */
+	else
+		/*
+		 * WDS = 1 (0x80), mulitplier = WD_TIMO, resolution = 1s (0x02)
+		 */
+		i2c_data[1] = wdt_margin<<2 | 0x82;
+
+	/*
+	 * M41T65 has three bits for watchdog resolution.  Don't set bit 7, as
+	 * that would be an invalid resolution.
+	 */
+	if (clientdata->features & M41T80_FEATURE_WD)
+		i2c_data[1] &= ~M41T80_WATCHDOG_RB2;
+
+	i2c_transfer(save_client->adapter, msgs1, 1);
+}
+
+/**
+ *	wdt_disable:
+ *
+ *	disables watchdog.
+ */
+static void wdt_disable(void)
+{
+	unsigned char i2c_data[2], i2c_buf[0x10];
+	struct i2c_msg msgs0[2] = {
+		{
+			.addr	= save_client->addr,
+			.flags	= 0,
+			.len	= 1,
+			.buf	= i2c_data,
+		},
+		{
+			.addr	= save_client->addr,
+			.flags	= I2C_M_RD,
+			.len	= 1,
+			.buf	= i2c_buf,
+		},
+	};
+	struct i2c_msg msgs1[1] = {
+		{
+			.addr	= save_client->addr,
+			.flags	= 0,
+			.len	= 2,
+			.buf	= i2c_data,
+		},
+	};
+
+	i2c_data[0] = 0x09;
+	i2c_transfer(save_client->adapter, msgs0, 2);
+
+	i2c_data[0] = 0x09;
+	i2c_data[1] = 0x00;
+	i2c_transfer(save_client->adapter, msgs1, 1);
+}
+
+/**
+ *	wdt_write:
+ *	@file: file handle to the watchdog
+ *	@buf: buffer to write (unused as data does not matter here
+ *	@count: count of bytes
+ *	@ppos: pointer to the position to write. No seeks allowed
+ *
+ *	A write to a watchdog device is defined as a keepalive signal. Any
+ *	write of data will do, as we we don't define content meaning.
+ */
+static ssize_t wdt_write(struct file *file, const char __user *buf,
+			 size_t count, loff_t *ppos)
+{
+	if (count) {
+		wdt_ping();
+		return 1;
+	}
+	return 0;
+}
+
+static ssize_t wdt_read(struct file *file, char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	return 0;
+}
+
+/**
+ *	wdt_ioctl:
+ *	@inode: inode of the device
+ *	@file: file handle to the device
+ *	@cmd: watchdog command
+ *	@arg: argument pointer
+ *
+ *	The watchdog API defines a common set of functions for all watchdogs
+ *	according to their available features. We only actually usefully support
+ *	querying capabilities and current status.
+ */
+static int wdt_ioctl(struct file *file, unsigned int cmd,
+		     unsigned long arg)
+{
+	int new_margin, rv;
+	static struct watchdog_info ident = {
+		.options = WDIOF_POWERUNDER | WDIOF_KEEPALIVEPING |
+			WDIOF_SETTIMEOUT,
+		.firmware_version = 1,
+		.identity = "M41T80 WTD"
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user((struct watchdog_info __user *)arg, &ident,
+				    sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(boot_flag, (int __user *)arg);
+	case WDIOC_KEEPALIVE:
+		wdt_ping();
+		return 0;
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_margin, (int __user *)arg))
+			return -EFAULT;
+		/* Arbitrary, can't find the card's limits */
+		if (new_margin < 1 || new_margin > 124)
+			return -EINVAL;
+		wdt_margin = new_margin;
+		wdt_ping();
+		/* Fall */
+	case WDIOC_GETTIMEOUT:
+		return put_user(wdt_margin, (int __user *)arg);
+
+	case WDIOC_SETOPTIONS:
+		if (copy_from_user(&rv, (int __user *)arg, sizeof(int)))
+			return -EFAULT;
+
+		if (rv & WDIOS_DISABLECARD) {
+			pr_info("disable watchdog\n");
+			wdt_disable();
+		}
+
+		if (rv & WDIOS_ENABLECARD) {
+			pr_info("enable watchdog\n");
+			wdt_ping();
+		}
+
+		return -EINVAL;
+	}
+	return -ENOTTY;
+}
+
+static long wdt_unlocked_ioctl(struct file *file, unsigned int cmd,
+			       unsigned long arg)
+{
+	int ret;
+
+	mutex_lock(&m41t80_rtc_mutex);
+	ret = wdt_ioctl(file, cmd, arg);
+	mutex_unlock(&m41t80_rtc_mutex);
+
+	return ret;
+}
+
+/**
+ *	wdt_open:
+ *	@inode: inode of device
+ *	@file: file handle to device
+ *
+ */
+static int wdt_open(struct inode *inode, struct file *file)
+{
+	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
+		mutex_lock(&m41t80_rtc_mutex);
+		if (test_and_set_bit(0, &wdt_is_open)) {
+			mutex_unlock(&m41t80_rtc_mutex);
+			return -EBUSY;
+		}
+		/*
+		 *	Activate
+		 */
+		wdt_is_open = 1;
+		mutex_unlock(&m41t80_rtc_mutex);
+		return nonseekable_open(inode, file);
+	}
+	return -ENODEV;
+}
+
+/**
+ *	wdt_close:
+ *	@inode: inode to board
+ *	@file: file handle to board
+ *
+ */
+static int wdt_release(struct inode *inode, struct file *file)
+{
+	if (MINOR(inode->i_rdev) == WATCHDOG_MINOR)
+		clear_bit(0, &wdt_is_open);
+	return 0;
+}
+
+/**
+ *	notify_sys:
+ *	@this: our notifier block
+ *	@code: the event being reported
+ *	@unused: unused
+ *
+ *	Our notifier is called on system shutdowns. We want to turn the card
+ *	off at reboot otherwise the machine will reboot again during memory
+ *	test or worse yet during the following fsck. This would suck, in fact
+ *	trust me - if it happens it does suck.
+ */
+static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
+			  void *unused)
+{
+	if (code == SYS_DOWN || code == SYS_HALT)
+		/* Disable Watchdog */
+		wdt_disable();
+	return NOTIFY_DONE;
+}
+
+static const struct file_operations wdt_fops = {
+	.owner	= THIS_MODULE,
+	.read	= wdt_read,
+	.unlocked_ioctl = wdt_unlocked_ioctl,
+	.write	= wdt_write,
+	.open	= wdt_open,
+	.release = wdt_release,
+	.llseek = no_llseek,
+};
+
+static struct miscdevice wdt_dev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &wdt_fops,
+};
+
+/*
+ *	The WDT card needs to learn about soft shutdowns in order to
+ *	turn the timebomb registers off.
+ */
+static struct notifier_block wdt_notifier = {
+	.notifier_call = wdt_notify_sys,
+};
+#endif /* CONFIG_RTC_DRV_M41T80_WDT */
+
+/*
+ *****************************************************************************
+ *
+ *	Driver Interface
+ *
+ *****************************************************************************
+ */
+static int m41t80_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int rc = 0;
+	struct rtc_device *rtc = NULL;
+	struct rtc_time tm;
+	struct m41t80_data *clientdata = NULL;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C
+				     | I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	clientdata = devm_kzalloc(&client->dev, sizeof(*clientdata),
+				GFP_KERNEL);
+	if (!clientdata)
+		return -ENOMEM;
+
+	clientdata->features = id->driver_data;
+	i2c_set_clientdata(client, clientdata);
+
+	rtc = devm_rtc_device_register(&client->dev, client->name,
+					&m41t80_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	clientdata->rtc = rtc;
+
+	/* Make sure HT (Halt Update) bit is cleared */
+	rc = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_HOUR);
+
+	if (rc >= 0 && rc & M41T80_ALHOUR_HT) {
+		if (clientdata->features & M41T80_FEATURE_HT) {
+			m41t80_get_datetime(client, &tm);
+			dev_info(&client->dev, "HT bit was set!\n");
+			dev_info(&client->dev,
+				 "Power Down at "
+				 "%04i-%02i-%02i %02i:%02i:%02i\n",
+				 tm.tm_year + 1900,
+				 tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
+				 tm.tm_min, tm.tm_sec);
+		}
+		rc = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_HOUR,
+					      rc & ~M41T80_ALHOUR_HT);
+	}
+
+	if (rc < 0) {
+		dev_err(&client->dev, "Can't clear HT bit\n");
+		return rc;
+	}
+
+	/* Make sure ST (stop) bit is cleared */
+	rc = i2c_smbus_read_byte_data(client, M41T80_REG_SEC);
+
+	if (rc >= 0 && rc & M41T80_SEC_ST)
+		rc = i2c_smbus_write_byte_data(client, M41T80_REG_SEC,
+					      rc & ~M41T80_SEC_ST);
+	if (rc < 0) {
+		dev_err(&client->dev, "Can't clear ST bit\n");
+		return rc;
+	}
+
+	rc = m41t80_sysfs_register(&client->dev);
+	if (rc)
+		return rc;
+
+#ifdef CONFIG_RTC_DRV_M41T80_WDT
+	if (clientdata->features & M41T80_FEATURE_HT) {
+		save_client = client;
+		rc = misc_register(&wdt_dev);
+		if (rc)
+			return rc;
+		rc = register_reboot_notifier(&wdt_notifier);
+		if (rc) {
+			misc_deregister(&wdt_dev);
+			return rc;
+		}
+	}
+#endif
+	return 0;
+}
+
+static int m41t80_remove(struct i2c_client *client)
+{
+#ifdef CONFIG_RTC_DRV_M41T80_WDT
+	struct m41t80_data *clientdata = i2c_get_clientdata(client);
+
+	if (clientdata->features & M41T80_FEATURE_HT) {
+		misc_deregister(&wdt_dev);
+		unregister_reboot_notifier(&wdt_notifier);
+	}
+#endif
+
+	return 0;
+}
+
+static struct i2c_driver m41t80_driver = {
+	.driver = {
+		.name = "rtc-m41t80",
+	},
+	.probe = m41t80_probe,
+	.remove = m41t80_remove,
+	.id_table = m41t80_id,
+};
+
+module_i2c_driver(m41t80_driver);
+
+MODULE_AUTHOR("Alexander Bigga <ab@mycable.de>");
+MODULE_DESCRIPTION("ST Microelectronics M41T80 series RTC I2C Client Driver");
+MODULE_LICENSE("GPL");