/*
   * Intersil ISL1208 rtc class driver
   *
   * Copyright 2005,2006 Hebert Valerio Riedel <hvr@gnu.org>
   *
   *  This program is free software; you can redistribute  it and/or modify it
   *  under  the terms of  the GNU General  Public License as published by the
   *  Free Software Foundation;  either version 2 of the  License, or (at your
   *  option) any later version.
   *
   */
  
  #include <linux/module.h>
  #include <linux/i2c.h>
  #include <linux/bcd.h>
  #include <linux/rtc.h>

  #define DRV_VERSION "0.3"

  
  /* Register map */
  /* rtc section */
  #define ISL1208_REG_SC  0x00
  #define ISL1208_REG_MN  0x01
  #define ISL1208_REG_HR  0x02

  #define ISL1208_REG_HR_MIL     (1<<7)	/* 24h/12h mode */
  #define ISL1208_REG_HR_PM      (1<<5)	/* PM/AM bit in 12h mode */

  #define ISL1208_REG_DT  0x03
  #define ISL1208_REG_MO  0x04
  #define ISL1208_REG_YR  0x05
  #define ISL1208_REG_DW  0x06
  #define ISL1208_RTC_SECTION_LEN 7
  
  /* control/status section */
  #define ISL1208_REG_SR  0x07

  #define ISL1208_REG_SR_ARST    (1<<7)	/* auto reset */
  #define ISL1208_REG_SR_XTOSCB  (1<<6)	/* crystal oscillator */
  #define ISL1208_REG_SR_WRTC    (1<<4)	/* write rtc */
  #define ISL1208_REG_SR_ALM     (1<<2)	/* alarm */
  #define ISL1208_REG_SR_BAT     (1<<1)	/* battery */
  #define ISL1208_REG_SR_RTCF    (1<<0)	/* rtc fail */

  #define ISL1208_REG_INT 0x08

  #define ISL1208_REG_INT_ALME   (1<<6)   /* alarm enable */
  #define ISL1208_REG_INT_IM     (1<<7)   /* interrupt/alarm mode */

  #define ISL1208_REG_09  0x09	/* reserved */

  #define ISL1208_REG_ATR 0x0a
  #define ISL1208_REG_DTR 0x0b
  
  /* alarm section */
  #define ISL1208_REG_SCA 0x0c
  #define ISL1208_REG_MNA 0x0d
  #define ISL1208_REG_HRA 0x0e
  #define ISL1208_REG_DTA 0x0f
  #define ISL1208_REG_MOA 0x10
  #define ISL1208_REG_DWA 0x11
  #define ISL1208_ALARM_SECTION_LEN 6
  
  /* user section */
  #define ISL1208_REG_USR1 0x12
  #define ISL1208_REG_USR2 0x13
  #define ISL1208_USR_SECTION_LEN 2

  static struct i2c_driver isl1208_driver;

  
  /* block read */
  static int
  isl1208_i2c_read_regs(struct i2c_client *client, u8 reg, u8 buf[],

  		      unsigned len)

  {
  	u8 reg_addr[1] = { reg };
  	struct i2c_msg msgs[2] = {

  		{client->addr, 0, sizeof(reg_addr), reg_addr}
  		,
  		{client->addr, I2C_M_RD, len, buf}

  	};
  	int ret;

  	BUG_ON(reg > ISL1208_REG_USR2);
  	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
  
  	ret = i2c_transfer(client->adapter, msgs, 2);
  	if (ret > 0)
  		ret = 0;
  	return ret;
  }
  
  /* block write */
  static int
  isl1208_i2c_set_regs(struct i2c_client *client, u8 reg, u8 const buf[],

  		     unsigned len)

  {
  	u8 i2c_buf[ISL1208_REG_USR2 + 2];
  	struct i2c_msg msgs[1] = {

  		{client->addr, 0, len + 1, i2c_buf}

  	};
  	int ret;

  	BUG_ON(reg > ISL1208_REG_USR2);
  	BUG_ON(reg + len > ISL1208_REG_USR2 + 1);
  
  	i2c_buf[0] = reg;
  	memcpy(&i2c_buf[1], &buf[0], len);
  
  	ret = i2c_transfer(client->adapter, msgs, 1);
  	if (ret > 0)
  		ret = 0;
  	return ret;
  }
  
  /* simple check to see wether we have a isl1208 */

  static int
  isl1208_i2c_validate_client(struct i2c_client *client)

  {
  	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
  	u8 zero_mask[ISL1208_RTC_SECTION_LEN] = {
  		0x80, 0x80, 0x40, 0xc0, 0xe0, 0x00, 0xf8
  	};
  	int i;
  	int ret;
  
  	ret = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
  	if (ret < 0)
  		return ret;
  
  	for (i = 0; i < ISL1208_RTC_SECTION_LEN; ++i) {

  		if (regs[i] & zero_mask[i])	/* check if bits are cleared */

  			return -ENODEV;
  	}
  
  	return 0;
  }

  static int
  isl1208_i2c_get_sr(struct i2c_client *client)

  {

  	int sr = i2c_smbus_read_byte_data(client, ISL1208_REG_SR);
  	if (sr < 0)
  		return -EIO;
  
  	return sr;

  }

  static int
  isl1208_i2c_get_atr(struct i2c_client *client)

  {
  	int atr = i2c_smbus_read_byte_data(client, ISL1208_REG_ATR);

  	if (atr < 0)

  		return atr;

  
  	/* The 6bit value in the ATR register controls the load
  	 * capacitance C_load * in steps of 0.25pF
  	 *
  	 * bit (1<<5) of the ATR register is inverted
  	 *
  	 * C_load(ATR=0x20) =  4.50pF
  	 * C_load(ATR=0x00) = 12.50pF
  	 * C_load(ATR=0x1f) = 20.25pF
  	 *
  	 */

  	atr &= 0x3f;		/* mask out lsb */
  	atr ^= 1 << 5;		/* invert 6th bit */
  	atr += 2 * 9;		/* add offset of 4.5pF; unit[atr] = 0.25pF */

  
  	return atr;
  }

  static int
  isl1208_i2c_get_dtr(struct i2c_client *client)

  {
  	int dtr = i2c_smbus_read_byte_data(client, ISL1208_REG_DTR);

  	if (dtr < 0)
  		return -EIO;
  
  	/* dtr encodes adjustments of {-60,-40,-20,0,20,40,60} ppm */

  	dtr = ((dtr & 0x3) * 20) * (dtr & (1 << 2) ? -1 : 1);

  
  	return dtr;
  }

  static int
  isl1208_i2c_get_usr(struct i2c_client *client)

  {
  	u8 buf[ISL1208_USR_SECTION_LEN] = { 0, };
  	int ret;

  	ret = isl1208_i2c_read_regs(client, ISL1208_REG_USR1, buf,
  				    ISL1208_USR_SECTION_LEN);

  	if (ret < 0)
  		return ret;
  
  	return (buf[1] << 8) | buf[0];
  }

  static int
  isl1208_i2c_set_usr(struct i2c_client *client, u16 usr)

  {
  	u8 buf[ISL1208_USR_SECTION_LEN];
  
  	buf[0] = usr & 0xff;
  	buf[1] = (usr >> 8) & 0xff;

  	return isl1208_i2c_set_regs(client, ISL1208_REG_USR1, buf,
  				    ISL1208_USR_SECTION_LEN);

  }

  static int

  isl1208_rtc_toggle_alarm(struct i2c_client *client, int enable)
  {
  	int icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
  
  	if (icr < 0) {
  		dev_err(&client->dev, "%s: reading INT failed
  ", __func__);
  		return icr;
  	}
  
  	if (enable)
  		icr |= ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM;
  	else
  		icr &= ~(ISL1208_REG_INT_ALME | ISL1208_REG_INT_IM);
  
  	icr = i2c_smbus_write_byte_data(client, ISL1208_REG_INT, icr);
  	if (icr < 0) {
  		dev_err(&client->dev, "%s: writing INT failed
  ", __func__);
  		return icr;
  	}
  
  	return 0;
  }
  
  static int

  isl1208_rtc_proc(struct device *dev, struct seq_file *seq)

  {
  	struct i2c_client *const client = to_i2c_client(dev);
  	int sr, dtr, atr, usr;
  
  	sr = isl1208_i2c_get_sr(client);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading SR failed
  ", __func__);
  		return sr;
  	}
  
  	seq_printf(seq, "status_reg\t:%s%s%s%s%s%s (0x%.2x)
  ",
  		   (sr & ISL1208_REG_SR_RTCF) ? " RTCF" : "",
  		   (sr & ISL1208_REG_SR_BAT) ? " BAT" : "",
  		   (sr & ISL1208_REG_SR_ALM) ? " ALM" : "",
  		   (sr & ISL1208_REG_SR_WRTC) ? " WRTC" : "",
  		   (sr & ISL1208_REG_SR_XTOSCB) ? " XTOSCB" : "",

  		   (sr & ISL1208_REG_SR_ARST) ? " ARST" : "", sr);

  
  	seq_printf(seq, "batt_status\t: %s
  ",
  		   (sr & ISL1208_REG_SR_RTCF) ? "bad" : "okay");
  
  	dtr = isl1208_i2c_get_dtr(client);

  	if (dtr >= 0 - 1)

  		seq_printf(seq, "digital_trim\t: %d ppm
  ", dtr);
  
  	atr = isl1208_i2c_get_atr(client);
  	if (atr >= 0)
  		seq_printf(seq, "analog_trim\t: %d.%.2d pF
  ",

  			   atr >> 2, (atr & 0x3) * 25);

  
  	usr = isl1208_i2c_get_usr(client);
  	if (usr >= 0)
  		seq_printf(seq, "user_data\t: 0x%.4x
  ", usr);
  
  	return 0;
  }

  static int
  isl1208_i2c_read_time(struct i2c_client *client, struct rtc_time *tm)

  {
  	int sr;
  	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };
  
  	sr = isl1208_i2c_get_sr(client);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading SR failed
  ", __func__);
  		return -EIO;
  	}
  
  	sr = isl1208_i2c_read_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading RTC section failed
  ",
  			__func__);
  		return sr;
  	}

  	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SC]);
  	tm->tm_min = bcd2bin(regs[ISL1208_REG_MN]);

  
  	/* HR field has a more complex interpretation */
  	{

  		const u8 _hr = regs[ISL1208_REG_HR];

  		if (_hr & ISL1208_REG_HR_MIL)	/* 24h format */

  			tm->tm_hour = bcd2bin(_hr & 0x3f);

  		else {
  			/* 12h format */

  			tm->tm_hour = bcd2bin(_hr & 0x1f);

  			if (_hr & ISL1208_REG_HR_PM)	/* PM flag set */

  				tm->tm_hour += 12;
  		}
  	}

  	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DT]);
  	tm->tm_mon = bcd2bin(regs[ISL1208_REG_MO]) - 1;	/* rtc starts at 1 */
  	tm->tm_year = bcd2bin(regs[ISL1208_REG_YR]) + 100;
  	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DW]);

  
  	return 0;
  }

  static int
  isl1208_i2c_read_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)

  {
  	struct rtc_time *const tm = &alarm->time;
  	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };

  	int icr, yr, sr = isl1208_i2c_get_sr(client);

  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading SR failed
  ", __func__);
  		return sr;
  	}
  
  	sr = isl1208_i2c_read_regs(client, ISL1208_REG_SCA, regs,

  				   ISL1208_ALARM_SECTION_LEN);

  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading alarm section failed
  ",
  			__func__);
  		return sr;
  	}
  
  	/* MSB of each alarm register is an enable bit */

  	tm->tm_sec = bcd2bin(regs[ISL1208_REG_SCA - ISL1208_REG_SCA] & 0x7f);
  	tm->tm_min = bcd2bin(regs[ISL1208_REG_MNA - ISL1208_REG_SCA] & 0x7f);
  	tm->tm_hour = bcd2bin(regs[ISL1208_REG_HRA - ISL1208_REG_SCA] & 0x3f);
  	tm->tm_mday = bcd2bin(regs[ISL1208_REG_DTA - ISL1208_REG_SCA] & 0x3f);

  	tm->tm_mon =

  		bcd2bin(regs[ISL1208_REG_MOA - ISL1208_REG_SCA] & 0x1f) - 1;
  	tm->tm_wday = bcd2bin(regs[ISL1208_REG_DWA - ISL1208_REG_SCA] & 0x03);

  	/* The alarm doesn't store the year so get it from the rtc section */
  	yr = i2c_smbus_read_byte_data(client, ISL1208_REG_YR);
  	if (yr < 0) {
  		dev_err(&client->dev, "%s: reading RTC YR failed
  ", __func__);
  		return yr;
  	}
  	tm->tm_year = bcd2bin(yr) + 100;
  
  	icr = i2c_smbus_read_byte_data(client, ISL1208_REG_INT);
  	if (icr < 0) {
  		dev_err(&client->dev, "%s: reading INT failed
  ", __func__);
  		return icr;
  	}
  	alarm->enabled = !!(icr & ISL1208_REG_INT_ALME);
  
  	return 0;
  }
  
  static int
  isl1208_i2c_set_alarm(struct i2c_client *client, struct rtc_wkalrm *alarm)
  {
  	struct rtc_time *alarm_tm = &alarm->time;
  	u8 regs[ISL1208_ALARM_SECTION_LEN] = { 0, };
  	const int offs = ISL1208_REG_SCA;
  	unsigned long rtc_secs, alarm_secs;
  	struct rtc_time rtc_tm;
  	int err, enable;
  
  	err = isl1208_i2c_read_time(client, &rtc_tm);
  	if (err)
  		return err;
  	err = rtc_tm_to_time(&rtc_tm, &rtc_secs);
  	if (err)
  		return err;
  	err = rtc_tm_to_time(alarm_tm, &alarm_secs);
  	if (err)
  		return err;
  
  	/* If the alarm time is before the current time disable the alarm */
  	if (!alarm->enabled || alarm_secs <= rtc_secs)
  		enable = 0x00;
  	else
  		enable = 0x80;
  
  	/* Program the alarm and enable it for each setting */
  	regs[ISL1208_REG_SCA - offs] = bin2bcd(alarm_tm->tm_sec) | enable;
  	regs[ISL1208_REG_MNA - offs] = bin2bcd(alarm_tm->tm_min) | enable;
  	regs[ISL1208_REG_HRA - offs] = bin2bcd(alarm_tm->tm_hour) |
  		ISL1208_REG_HR_MIL | enable;
  
  	regs[ISL1208_REG_DTA - offs] = bin2bcd(alarm_tm->tm_mday) | enable;
  	regs[ISL1208_REG_MOA - offs] = bin2bcd(alarm_tm->tm_mon + 1) | enable;
  	regs[ISL1208_REG_DWA - offs] = bin2bcd(alarm_tm->tm_wday & 7) | enable;
  
  	/* write ALARM registers */
  	err = isl1208_i2c_set_regs(client, offs, regs,
  				  ISL1208_ALARM_SECTION_LEN);
  	if (err < 0) {
  		dev_err(&client->dev, "%s: writing ALARM section failed
  ",
  			__func__);
  		return err;
  	}
  
  	err = isl1208_rtc_toggle_alarm(client, enable);
  	if (err)
  		return err;

  	return 0;
  }

  static int
  isl1208_rtc_read_time(struct device *dev, struct rtc_time *tm)

  {
  	return isl1208_i2c_read_time(to_i2c_client(dev), tm);
  }

  static int
  isl1208_i2c_set_time(struct i2c_client *client, struct rtc_time const *tm)

  {
  	int sr;
  	u8 regs[ISL1208_RTC_SECTION_LEN] = { 0, };

  	/* The clock has an 8 bit wide bcd-coded register (they never learn)
  	 * for the year. tm_year is an offset from 1900 and we are interested
  	 * in the 2000-2099 range, so any value less than 100 is invalid.
  	 */
  	if (tm->tm_year < 100)
  		return -EINVAL;

  	regs[ISL1208_REG_SC] = bin2bcd(tm->tm_sec);
  	regs[ISL1208_REG_MN] = bin2bcd(tm->tm_min);
  	regs[ISL1208_REG_HR] = bin2bcd(tm->tm_hour) | ISL1208_REG_HR_MIL;

  	regs[ISL1208_REG_DT] = bin2bcd(tm->tm_mday);
  	regs[ISL1208_REG_MO] = bin2bcd(tm->tm_mon + 1);
  	regs[ISL1208_REG_YR] = bin2bcd(tm->tm_year - 100);

  	regs[ISL1208_REG_DW] = bin2bcd(tm->tm_wday & 7);

  
  	sr = isl1208_i2c_get_sr(client);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: reading SR failed
  ", __func__);
  		return sr;
  	}
  
  	/* set WRTC */

  	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,

  				       sr | ISL1208_REG_SR_WRTC);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: writing SR failed
  ", __func__);
  		return sr;
  	}
  
  	/* write RTC registers */
  	sr = isl1208_i2c_set_regs(client, 0, regs, ISL1208_RTC_SECTION_LEN);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: writing RTC section failed
  ",
  			__func__);
  		return sr;
  	}
  
  	/* clear WRTC again */

  	sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR,

  				       sr & ~ISL1208_REG_SR_WRTC);
  	if (sr < 0) {
  		dev_err(&client->dev, "%s: writing SR failed
  ", __func__);
  		return sr;
  	}
  
  	return 0;
  }

  static int
  isl1208_rtc_set_time(struct device *dev, struct rtc_time *tm)

  {
  	return isl1208_i2c_set_time(to_i2c_client(dev), tm);
  }

  static int
  isl1208_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)

  {
  	return isl1208_i2c_read_alarm(to_i2c_client(dev), alarm);
  }

  static int
  isl1208_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
  {
  	return isl1208_i2c_set_alarm(to_i2c_client(dev), alarm);
  }
  
  static irqreturn_t
  isl1208_rtc_interrupt(int irq, void *data)
  {
  	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
  	struct i2c_client *client = data;
  	int handled = 0, sr, err;
  
  	/*
  	 * I2C reads get NAK'ed if we read straight away after an interrupt?
  	 * Using a mdelay/msleep didn't seem to help either, so we work around
  	 * this by continually trying to read the register for a short time.
  	 */
  	while (1) {
  		sr = isl1208_i2c_get_sr(client);
  		if (sr >= 0)
  			break;
  
  		if (time_after(jiffies, timeout)) {
  			dev_err(&client->dev, "%s: reading SR failed
  ",
  				__func__);
  			return sr;
  		}
  	}
  
  	if (sr & ISL1208_REG_SR_ALM) {
  		dev_dbg(&client->dev, "alarm!
  ");
  
  		/* Clear the alarm */
  		sr &= ~ISL1208_REG_SR_ALM;
  		sr = i2c_smbus_write_byte_data(client, ISL1208_REG_SR, sr);
  		if (sr < 0)
  			dev_err(&client->dev, "%s: writing SR failed
  ",
  				__func__);
  		else
  			handled = 1;
  
  		/* Disable the alarm */
  		err = isl1208_rtc_toggle_alarm(client, 0);
  		if (err)
  			return err;
  	}
  
  	return handled ? IRQ_HANDLED : IRQ_NONE;
  }

  static const struct rtc_class_ops isl1208_rtc_ops = {

  	.proc = isl1208_rtc_proc,
  	.read_time = isl1208_rtc_read_time,
  	.set_time = isl1208_rtc_set_time,
  	.read_alarm = isl1208_rtc_read_alarm,

  	.set_alarm = isl1208_rtc_set_alarm,

  };
  
  /* sysfs interface */

  static ssize_t
  isl1208_sysfs_show_atrim(struct device *dev,
  			 struct device_attribute *attr, char *buf)

  {

  	int atr = isl1208_i2c_get_atr(to_i2c_client(dev));

  	if (atr < 0)
  		return atr;

  	return sprintf(buf, "%d.%.2d pF
  ", atr >> 2, (atr & 0x3) * 25);

  }

  static DEVICE_ATTR(atrim, S_IRUGO, isl1208_sysfs_show_atrim, NULL);

  static ssize_t
  isl1208_sysfs_show_dtrim(struct device *dev,
  			 struct device_attribute *attr, char *buf)

  {

  	int dtr = isl1208_i2c_get_dtr(to_i2c_client(dev));

  	if (dtr < 0)
  		return dtr;
  
  	return sprintf(buf, "%d ppm
  ", dtr);
  }

  static DEVICE_ATTR(dtrim, S_IRUGO, isl1208_sysfs_show_dtrim, NULL);

  static ssize_t
  isl1208_sysfs_show_usr(struct device *dev,
  		       struct device_attribute *attr, char *buf)

  {

  	int usr = isl1208_i2c_get_usr(to_i2c_client(dev));

  	if (usr < 0)
  		return usr;
  
  	return sprintf(buf, "0x%.4x
  ", usr);
  }

  static ssize_t
  isl1208_sysfs_store_usr(struct device *dev,
  			struct device_attribute *attr,
  			const char *buf, size_t count)

  {
  	int usr = -1;
  
  	if (buf[0] == '0' && (buf[1] == 'x' || buf[1] == 'X')) {
  		if (sscanf(buf, "%x", &usr) != 1)
  			return -EINVAL;
  	} else {
  		if (sscanf(buf, "%d", &usr) != 1)
  			return -EINVAL;
  	}
  
  	if (usr < 0 || usr > 0xffff)
  		return -EINVAL;
  
  	return isl1208_i2c_set_usr(to_i2c_client(dev), usr) ? -EIO : count;
  }

  static DEVICE_ATTR(usr, S_IRUGO | S_IWUSR, isl1208_sysfs_show_usr,
  		   isl1208_sysfs_store_usr);

  static struct attribute *isl1208_rtc_attrs[] = {
  	&dev_attr_atrim.attr,
  	&dev_attr_dtrim.attr,
  	&dev_attr_usr.attr,
  	NULL
  };

  static const struct attribute_group isl1208_rtc_sysfs_files = {
  	.attrs	= isl1208_rtc_attrs,
  };

  
  static int

  isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)

  {
  	int rc = 0;
  	struct rtc_device *rtc;

  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  		return -ENODEV;

  	if (isl1208_i2c_validate_client(client) < 0)
  		return -ENODEV;
  
  	dev_info(&client->dev,

  		 "chip found, driver version " DRV_VERSION "
  ");

  	if (client->irq > 0) {
  		rc = request_threaded_irq(client->irq, NULL,
  					  isl1208_rtc_interrupt,
  					  IRQF_SHARED,
  					  isl1208_driver.driver.name, client);
  		if (!rc) {
  			device_init_wakeup(&client->dev, 1);
  			enable_irq_wake(client->irq);
  		} else {
  			dev_err(&client->dev,
  				"Unable to request irq %d, no alarm support
  ",
  				client->irq);
  			client->irq = 0;
  		}
  	}

  	rtc = rtc_device_register(isl1208_driver.driver.name,

  				  &client->dev, &isl1208_rtc_ops,
  				  THIS_MODULE);

  	if (IS_ERR(rtc)) {
  		rc = PTR_ERR(rtc);
  		goto exit_free_irq;
  	}

  	i2c_set_clientdata(client, rtc);

  	rc = isl1208_i2c_get_sr(client);

  	if (rc < 0) {

  		dev_err(&client->dev, "reading status failed
  ");
  		goto exit_unregister;

  	}
  
  	if (rc & ISL1208_REG_SR_RTCF)

  		dev_warn(&client->dev, "rtc power failure detected, "

  			 "please set clock.
  ");

  	rc = sysfs_create_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);

  	if (rc)
  		goto exit_unregister;

  
  	return 0;

  exit_unregister:

  	rtc_device_unregister(rtc);

  exit_free_irq:
  	if (client->irq)
  		free_irq(client->irq, client);

  	return rc;

  }
  
  static int

  isl1208_remove(struct i2c_client *client)

  {

  	struct rtc_device *rtc = i2c_get_clientdata(client);

  	sysfs_remove_group(&client->dev.kobj, &isl1208_rtc_sysfs_files);

  	rtc_device_unregister(rtc);

  	if (client->irq)
  		free_irq(client->irq, client);

  
  	return 0;
  }

  static const struct i2c_device_id isl1208_id[] = {
  	{ "isl1208", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, isl1208_id);

  static struct i2c_driver isl1208_driver = {
  	.driver = {
  		   .name = "rtc-isl1208",
  		   },
  	.probe = isl1208_probe,
  	.remove = isl1208_remove,

  	.id_table = isl1208_id,

  };

  static int __init
  isl1208_init(void)

  {
  	return i2c_add_driver(&isl1208_driver);
  }

  static void __exit
  isl1208_exit(void)

  {
  	i2c_del_driver(&isl1208_driver);
  }
  
  MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
  MODULE_DESCRIPTION("Intersil ISL1208 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);
  
  module_init(isl1208_init);
  module_exit(isl1208_exit);