/*
 * 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.
 *
 */

#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("rtc-m41t80: disable watchdog\n");
                        wdt_disable();
                }

                if (rv & WDIOS_ENABLECARD) {
                        pr_info("rtc-m41t80: 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");