// SPDX-License-Identifier: GPL-2.0-only

  /*

   * An I2C driver for Ricoh RS5C372, R2025S/D and RV5C38[67] RTCs

   *
   * Copyright (C) 2005 Pavel Mironchik <pmironchik@optifacio.net>
   * Copyright (C) 2006 Tower Technologies

   * Copyright (C) 2008 Paul Mundt

   */
  
  #include <linux/i2c.h>
  #include <linux/rtc.h>
  #include <linux/bcd.h>

  #include <linux/slab.h>

  #include <linux/module.h>

  #include <linux/of_device.h>

  /*
   * Ricoh has a family of I2C based RTCs, which differ only slightly from
   * each other.  Differences center on pinout (e.g. how many interrupts,
   * output clock, etc) and how the control registers are used.  The '372
   * is significant only because that's the one this driver first supported.
   */

  #define RS5C372_REG_SECS	0
  #define RS5C372_REG_MINS	1
  #define RS5C372_REG_HOURS	2
  #define RS5C372_REG_WDAY	3
  #define RS5C372_REG_DAY		4
  #define RS5C372_REG_MONTH	5
  #define RS5C372_REG_YEAR	6
  #define RS5C372_REG_TRIM	7

  #	define RS5C372_TRIM_XSL		0x80
  #	define RS5C372_TRIM_MASK	0x7F
  
  #define RS5C_REG_ALARM_A_MIN	8			/* or ALARM_W */
  #define RS5C_REG_ALARM_A_HOURS	9
  #define RS5C_REG_ALARM_A_WDAY	10
  
  #define RS5C_REG_ALARM_B_MIN	11			/* or ALARM_D */
  #define RS5C_REG_ALARM_B_HOURS	12
  #define RS5C_REG_ALARM_B_WDAY	13			/* (ALARM_B only) */
  
  #define RS5C_REG_CTRL1		14
  #	define RS5C_CTRL1_AALE		(1 << 7)	/* or WALE */
  #	define RS5C_CTRL1_BALE		(1 << 6)	/* or DALE */
  #	define RV5C387_CTRL1_24		(1 << 5)
  #	define RS5C372A_CTRL1_SL1	(1 << 5)
  #	define RS5C_CTRL1_CT_MASK	(7 << 0)
  #	define RS5C_CTRL1_CT0		(0 << 0)	/* no periodic irq */
  #	define RS5C_CTRL1_CT4		(4 << 0)	/* 1 Hz level irq */
  #define RS5C_REG_CTRL2		15
  #	define RS5C372_CTRL2_24		(1 << 5)

  #	define RS5C_CTRL2_XSTP		(1 << 4)	/* only if !R2x2x */

  #	define R2x2x_CTRL2_VDET		(1 << 6)	/* only if  R2x2x */
  #	define R2x2x_CTRL2_XSTP		(1 << 5)	/* only if  R2x2x */
  #	define R2x2x_CTRL2_PON		(1 << 4)	/* only if  R2x2x */

  #	define RS5C_CTRL2_CTFG		(1 << 2)
  #	define RS5C_CTRL2_AAFG		(1 << 1)	/* or WAFG */
  #	define RS5C_CTRL2_BAFG		(1 << 0)	/* or DAFG */
  
  
  /* to read (style 1) or write registers starting at R */
  #define RS5C_ADDR(R)		(((R) << 4) | 0)
  
  
  enum rtc_type {
  	rtc_undef = 0,

  	rtc_r2025sd,

  	rtc_r2221tl,

  	rtc_rs5c372a,
  	rtc_rs5c372b,
  	rtc_rv5c386,
  	rtc_rv5c387a,
  };

  static const struct i2c_device_id rs5c372_id[] = {

  	{ "r2025sd", rtc_r2025sd },

  	{ "r2221tl", rtc_r2221tl },

  	{ "rs5c372a", rtc_rs5c372a },
  	{ "rs5c372b", rtc_rs5c372b },
  	{ "rv5c386", rtc_rv5c386 },
  	{ "rv5c387a", rtc_rv5c387a },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, rs5c372_id);

  static const struct of_device_id rs5c372_of_match[] = {
  	{
  		.compatible = "ricoh,r2025sd",
  		.data = (void *)rtc_r2025sd
  	},
  	{
  		.compatible = "ricoh,r2221tl",
  		.data = (void *)rtc_r2221tl
  	},
  	{
  		.compatible = "ricoh,rs5c372a",
  		.data = (void *)rtc_rs5c372a
  	},
  	{
  		.compatible = "ricoh,rs5c372b",
  		.data = (void *)rtc_rs5c372b
  	},
  	{
  		.compatible = "ricoh,rv5c386",
  		.data = (void *)rtc_rv5c386
  	},
  	{
  		.compatible = "ricoh,rv5c387a",
  		.data = (void *)rtc_rv5c387a
  	},
  	{ }
  };
  MODULE_DEVICE_TABLE(of, rs5c372_of_match);

  /* REVISIT:  this assumes that:
   *  - we're in the 21st century, so it's safe to ignore the century
   *    bit for rv5c38[67] (REG_MONTH bit 7);
   *  - we should use ALARM_A not ALARM_B (may be wrong on some boards)
   */
  struct rs5c372 {
  	struct i2c_client	*client;
  	struct rtc_device	*rtc;
  	enum rtc_type		type;
  	unsigned		time24:1;
  	unsigned		has_irq:1;

  	unsigned		smbus:1;

  	char			buf[17];
  	char			*regs;

  };

  static int rs5c_get_regs(struct rs5c372 *rs5c)
  {
  	struct i2c_client	*client = rs5c->client;
  	struct i2c_msg		msgs[] = {

  		{
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = sizeof(rs5c->buf),
  			.buf = rs5c->buf
  		},

  	};
  
  	/* This implements the third reading method from the datasheet, using
  	 * an internal address that's reset after each transaction (by STOP)
  	 * to 0x0f ... so we read extra registers, and skip the first one.
  	 *
  	 * The first method doesn't work with the iop3xx adapter driver, on at
  	 * least 80219 chips; this works around that bug.

  	 *
  	 * The third method on the other hand doesn't work for the SMBus-only
  	 * configurations, so we use the the first method there, stripping off
  	 * the extra register in the process.

  	 */

  	if (rs5c->smbus) {
  		int addr = RS5C_ADDR(RS5C372_REG_SECS);
  		int size = sizeof(rs5c->buf) - 1;
  
  		if (i2c_smbus_read_i2c_block_data(client, addr, size,
  						  rs5c->buf + 1) != size) {
  			dev_warn(&client->dev, "can't read registers
  ");
  			return -EIO;
  		}
  	} else {
  		if ((i2c_transfer(client->adapter, msgs, 1)) != 1) {
  			dev_warn(&client->dev, "can't read registers
  ");
  			return -EIO;
  		}

  	}

  	dev_dbg(&client->dev,

  		"%3ph (%02x) %3ph (%02x), %3ph, %3ph; %02x %02x
  ",
  		rs5c->regs + 0, rs5c->regs[3],
  		rs5c->regs + 4, rs5c->regs[7],
  		rs5c->regs + 8, rs5c->regs + 11,
  		rs5c->regs[14], rs5c->regs[15]);

  	return 0;
  }

  static unsigned rs5c_reg2hr(struct rs5c372 *rs5c, unsigned reg)
  {
  	unsigned	hour;

  	if (rs5c->time24)

  		return bcd2bin(reg & 0x3f);

  	hour = bcd2bin(reg & 0x1f);

  	if (hour == 12)
  		hour = 0;
  	if (reg & 0x20)
  		hour += 12;
  	return hour;
  }
  
  static unsigned rs5c_hr2reg(struct rs5c372 *rs5c, unsigned hour)

  {

  	if (rs5c->time24)

  		return bin2bcd(hour);

  
  	if (hour > 12)

  		return 0x20 | bin2bcd(hour - 12);

  	if (hour == 12)

  		return 0x20 | bin2bcd(12);

  	if (hour == 0)

  		return bin2bcd(12);
  	return bin2bcd(hour);

  }

  static int rs5c372_rtc_read_time(struct device *dev, struct rtc_time *tm)

  {

  	struct i2c_client *client = to_i2c_client(dev);

  	struct rs5c372	*rs5c = i2c_get_clientdata(client);
  	int		status = rs5c_get_regs(rs5c);

  	unsigned char ctrl2 = rs5c->regs[RS5C_REG_CTRL2];

  	if (status < 0)
  		return status;

  	switch (rs5c->type) {
  	case rtc_r2025sd:
  	case rtc_r2221tl:
  		if ((rs5c->type == rtc_r2025sd && !(ctrl2 & R2x2x_CTRL2_XSTP)) ||
  		    (rs5c->type == rtc_r2221tl &&  (ctrl2 & R2x2x_CTRL2_XSTP))) {
  			dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.
  ");
  			return -EINVAL;
  		}
  		break;
  	default:
  		if (ctrl2 & RS5C_CTRL2_XSTP) {
  			dev_warn(&client->dev, "rtc oscillator interruption detected. Please reset the rtc clock.
  ");
  			return -EINVAL;
  		}
  	}

  	tm->tm_sec = bcd2bin(rs5c->regs[RS5C372_REG_SECS] & 0x7f);
  	tm->tm_min = bcd2bin(rs5c->regs[RS5C372_REG_MINS] & 0x7f);

  	tm->tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C372_REG_HOURS]);

  	tm->tm_wday = bcd2bin(rs5c->regs[RS5C372_REG_WDAY] & 0x07);
  	tm->tm_mday = bcd2bin(rs5c->regs[RS5C372_REG_DAY] & 0x3f);

  
  	/* tm->tm_mon is zero-based */

  	tm->tm_mon = bcd2bin(rs5c->regs[RS5C372_REG_MONTH] & 0x1f) - 1;

  
  	/* year is 1900 + tm->tm_year */

  	tm->tm_year = bcd2bin(rs5c->regs[RS5C372_REG_YEAR]) + 100;

  
  	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  		"mday=%d, mon=%d, year=%d, wday=%d
  ",

  		__func__,

  		tm->tm_sec, tm->tm_min, tm->tm_hour,
  		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

  	return 0;

  }

  static int rs5c372_rtc_set_time(struct device *dev, struct rtc_time *tm)

  {

  	struct i2c_client *client = to_i2c_client(dev);

  	struct rs5c372	*rs5c = i2c_get_clientdata(client);

  	unsigned char	buf[7];

  	unsigned char	ctrl2;

  	int		addr;

  	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d "

  		"mday=%d, mon=%d, year=%d, wday=%d
  ",

  		__func__,

  		tm->tm_sec, tm->tm_min, tm->tm_hour,

  		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

  	addr   = RS5C_ADDR(RS5C372_REG_SECS);

  	buf[0] = bin2bcd(tm->tm_sec);
  	buf[1] = bin2bcd(tm->tm_min);

  	buf[2] = rs5c_hr2reg(rs5c, tm->tm_hour);

  	buf[3] = bin2bcd(tm->tm_wday);
  	buf[4] = bin2bcd(tm->tm_mday);
  	buf[5] = bin2bcd(tm->tm_mon + 1);
  	buf[6] = bin2bcd(tm->tm_year - 100);

  	if (i2c_smbus_write_i2c_block_data(client, addr, sizeof(buf), buf) < 0) {

  		dev_dbg(&client->dev, "%s: write error in line %i
  ",
  			__func__, __LINE__);
  		return -EIO;
  	}
  
  	addr = RS5C_ADDR(RS5C_REG_CTRL2);
  	ctrl2 = i2c_smbus_read_byte_data(client, addr);
  
  	/* clear rtc warning bits */
  	switch (rs5c->type) {
  	case rtc_r2025sd:
  	case rtc_r2221tl:
  		ctrl2 &= ~(R2x2x_CTRL2_VDET | R2x2x_CTRL2_PON);
  		if (rs5c->type == rtc_r2025sd)
  			ctrl2 |= R2x2x_CTRL2_XSTP;
  		else
  			ctrl2 &= ~R2x2x_CTRL2_XSTP;
  		break;
  	default:
  		ctrl2 &= ~RS5C_CTRL2_XSTP;
  		break;
  	}
  
  	if (i2c_smbus_write_byte_data(client, addr, ctrl2) < 0) {
  		dev_dbg(&client->dev, "%s: write error in line %i
  ",
  			__func__, __LINE__);

  		return -EIO;
  	}
  
  	return 0;
  }

  #if IS_ENABLED(CONFIG_RTC_INTF_PROC)

  #define	NEED_TRIM
  #endif

  #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)

  #define	NEED_TRIM
  #endif
  
  #ifdef	NEED_TRIM

  static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
  {

  	struct rs5c372 *rs5c372 = i2c_get_clientdata(client);

  	u8 tmp = rs5c372->regs[RS5C372_REG_TRIM];

  	if (osc)

  		*osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;

  	if (trim) {

  		dev_dbg(&client->dev, "%s: raw trim=%x
  ", __func__, tmp);

  		tmp &= RS5C372_TRIM_MASK;
  		if (tmp & 0x3e) {
  			int t = tmp & 0x3f;
  
  			if (tmp & 0x40)
  				t = (~t | (s8)0xc0) + 1;
  			else
  				t = t - 1;
  
  			tmp = t * 2;
  		} else
  			tmp = 0;
  		*trim = tmp;

  	}

  
  	return 0;
  }

  #endif

  static int rs5c_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct i2c_client	*client = to_i2c_client(dev);
  	struct rs5c372		*rs5c = i2c_get_clientdata(client);
  	unsigned char		buf;
  	int			status, addr;
  
  	buf = rs5c->regs[RS5C_REG_CTRL1];
  
  	if (!rs5c->has_irq)
  		return -EINVAL;
  
  	status = rs5c_get_regs(rs5c);
  	if (status < 0)
  		return status;
  
  	addr = RS5C_ADDR(RS5C_REG_CTRL1);
  	if (enabled)
  		buf |= RS5C_CTRL1_AALE;
  	else
  		buf &= ~RS5C_CTRL1_AALE;
  
  	if (i2c_smbus_write_byte_data(client, addr, buf) < 0) {

  		dev_warn(dev, "can't update alarm
  ");

  		status = -EIO;
  	} else
  		rs5c->regs[RS5C_REG_CTRL1] = buf;
  
  	return status;
  }

  /* NOTE:  Since RTC_WKALM_{RD,SET} were originally defined for EFI,
   * which only exposes a polled programming interface; and since
   * these calls map directly to those EFI requests; we don't demand
   * we have an IRQ for this chip when we go through this API.
   *
   * The older x86_pc derived RTC_ALM_{READ,SET} calls require irqs
   * though, managed through RTC_AIE_{ON,OFF} requests.
   */
  
  static int rs5c_read_alarm(struct device *dev, struct rtc_wkalrm *t)
  {
  	struct i2c_client	*client = to_i2c_client(dev);
  	struct rs5c372		*rs5c = i2c_get_clientdata(client);
  	int			status;
  
  	status = rs5c_get_regs(rs5c);
  	if (status < 0)
  		return status;
  
  	/* report alarm time */
  	t->time.tm_sec = 0;

  	t->time.tm_min = bcd2bin(rs5c->regs[RS5C_REG_ALARM_A_MIN] & 0x7f);

  	t->time.tm_hour = rs5c_reg2hr(rs5c, rs5c->regs[RS5C_REG_ALARM_A_HOURS]);

  
  	/* ... and status */
  	t->enabled = !!(rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE);
  	t->pending = !!(rs5c->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_AAFG);
  
  	return 0;
  }
  
  static int rs5c_set_alarm(struct device *dev, struct rtc_wkalrm *t)
  {
  	struct i2c_client	*client = to_i2c_client(dev);
  	struct rs5c372		*rs5c = i2c_get_clientdata(client);

  	int			status, addr, i;
  	unsigned char		buf[3];

  
  	/* only handle up to 24 hours in the future, like RTC_ALM_SET */
  	if (t->time.tm_mday != -1
  			|| t->time.tm_mon != -1
  			|| t->time.tm_year != -1)
  		return -EINVAL;
  
  	/* REVISIT: round up tm_sec */
  
  	/* if needed, disable irq (clears pending status) */
  	status = rs5c_get_regs(rs5c);
  	if (status < 0)
  		return status;
  	if (rs5c->regs[RS5C_REG_CTRL1] & RS5C_CTRL1_AALE) {

  		addr = RS5C_ADDR(RS5C_REG_CTRL1);
  		buf[0] = rs5c->regs[RS5C_REG_CTRL1] & ~RS5C_CTRL1_AALE;
  		if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0) {

  			dev_dbg(dev, "can't disable alarm
  ");

  			return -EIO;
  		}

  		rs5c->regs[RS5C_REG_CTRL1] = buf[0];

  	}
  
  	/* set alarm */

  	buf[0] = bin2bcd(t->time.tm_min);

  	buf[1] = rs5c_hr2reg(rs5c, t->time.tm_hour);
  	buf[2] = 0x7f;	/* any/all days */
  
  	for (i = 0; i < sizeof(buf); i++) {
  		addr = RS5C_ADDR(RS5C_REG_ALARM_A_MIN + i);
  		if (i2c_smbus_write_byte_data(client, addr, buf[i]) < 0) {

  			dev_dbg(dev, "can't set alarm time
  ");

  			return -EIO;
  		}

  	}
  
  	/* ... and maybe enable its irq */
  	if (t->enabled) {

  		addr = RS5C_ADDR(RS5C_REG_CTRL1);
  		buf[0] = rs5c->regs[RS5C_REG_CTRL1] | RS5C_CTRL1_AALE;
  		if (i2c_smbus_write_byte_data(client, addr, buf[0]) < 0)

  			dev_warn(dev, "can't enable alarm
  ");

  		rs5c->regs[RS5C_REG_CTRL1] = buf[0];

  	}
  
  	return 0;
  }

  #if IS_ENABLED(CONFIG_RTC_INTF_PROC)

  static int rs5c372_rtc_proc(struct device *dev, struct seq_file *seq)
  {
  	int err, osc, trim;

  	err = rs5c372_get_trim(to_i2c_client(dev), &osc, &trim);
  	if (err == 0) {

  		seq_printf(seq, "crystal\t\t: %d.%03d KHz
  ",
  				osc / 1000, osc % 1000);
  		seq_printf(seq, "trim\t\t: %d
  ", trim);

  	}
  
  	return 0;
  }

  #else
  #define	rs5c372_rtc_proc	NULL
  #endif

  static const struct rtc_class_ops rs5c372_rtc_ops = {

  	.proc		= rs5c372_rtc_proc,
  	.read_time	= rs5c372_rtc_read_time,
  	.set_time	= rs5c372_rtc_set_time,

  	.read_alarm	= rs5c_read_alarm,
  	.set_alarm	= rs5c_set_alarm,

  	.alarm_irq_enable = rs5c_rtc_alarm_irq_enable,

  };

  #if IS_ENABLED(CONFIG_RTC_INTF_SYSFS)

  static ssize_t rs5c372_sysfs_show_trim(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {

  	int err, trim;

  	err = rs5c372_get_trim(to_i2c_client(dev), NULL, &trim);
  	if (err)
  		return err;

  	return sprintf(buf, "%d
  ", trim);

  }
  static DEVICE_ATTR(trim, S_IRUGO, rs5c372_sysfs_show_trim, NULL);
  
  static ssize_t rs5c372_sysfs_show_osc(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {

  	int err, osc;

  	err = rs5c372_get_trim(to_i2c_client(dev), &osc, NULL);
  	if (err)
  		return err;

  	return sprintf(buf, "%d.%03d KHz
  ", osc / 1000, osc % 1000);

  }
  static DEVICE_ATTR(osc, S_IRUGO, rs5c372_sysfs_show_osc, NULL);

  static int rs5c_sysfs_register(struct device *dev)

  {

  	int err;
  
  	err = device_create_file(dev, &dev_attr_trim);
  	if (err)
  		return err;
  	err = device_create_file(dev, &dev_attr_osc);
  	if (err)
  		device_remove_file(dev, &dev_attr_trim);
  
  	return err;
  }

  static void rs5c_sysfs_unregister(struct device *dev)
  {
  	device_remove_file(dev, &dev_attr_trim);
  	device_remove_file(dev, &dev_attr_osc);
  }

  #else
  static int rs5c_sysfs_register(struct device *dev)
  {
  	return 0;

  }

  
  static void rs5c_sysfs_unregister(struct device *dev)
  {
  	/* nothing */
  }

  #endif	/* SYSFS */
  
  static struct i2c_driver rs5c372_driver;

  static int rs5c_oscillator_setup(struct rs5c372 *rs5c372)
  {
  	unsigned char buf[2];
  	int addr, i, ret = 0;

  	addr   = RS5C_ADDR(RS5C_REG_CTRL1);
  	buf[0] = rs5c372->regs[RS5C_REG_CTRL1];
  	buf[1] = rs5c372->regs[RS5C_REG_CTRL2];

  	switch (rs5c372->type) {
  	case rtc_r2025sd:
  		if (buf[1] & R2x2x_CTRL2_XSTP)

  			return ret;

  		break;
  	case rtc_r2221tl:
  		if (!(buf[1] & R2x2x_CTRL2_XSTP))
  			return ret;

  		break;

  	default:
  		if (!(buf[1] & RS5C_CTRL2_XSTP))

  			return ret;

  		break;

  	}

  	/* use 24hr mode */
  	switch (rs5c372->type) {
  	case rtc_rs5c372a:
  	case rtc_rs5c372b:
  		buf[1] |= RS5C372_CTRL2_24;
  		rs5c372->time24 = 1;
  		break;

  	case rtc_r2025sd:

  	case rtc_r2221tl:

  	case rtc_rv5c386:
  	case rtc_rv5c387a:
  		buf[0] |= RV5C387_CTRL1_24;
  		rs5c372->time24 = 1;
  		break;
  	default:
  		/* impossible */
  		break;
  	}
  
  	for (i = 0; i < sizeof(buf); i++) {
  		addr = RS5C_ADDR(RS5C_REG_CTRL1 + i);
  		ret = i2c_smbus_write_byte_data(rs5c372->client, addr, buf[i]);
  		if (unlikely(ret < 0))
  			return ret;
  	}
  
  	rs5c372->regs[RS5C_REG_CTRL1] = buf[0];
  	rs5c372->regs[RS5C_REG_CTRL2] = buf[1];
  
  	return 0;
  }

  static int rs5c372_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)

  {
  	int err = 0;

  	int smbus_mode = 0;

  	struct rs5c372 *rs5c372;

  	dev_dbg(&client->dev, "%s
  ", __func__);

  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
  			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK)) {
  		/*
  		 * If we don't have any master mode adapter, try breaking
  		 * it down in to the barest of capabilities.
  		 */
  		if (i2c_check_functionality(client->adapter,
  				I2C_FUNC_SMBUS_BYTE_DATA |
  				I2C_FUNC_SMBUS_I2C_BLOCK))
  			smbus_mode = 1;
  		else {
  			/* Still no good, give up */
  			err = -ENODEV;
  			goto exit;
  		}

  	}

  	rs5c372 = devm_kzalloc(&client->dev, sizeof(struct rs5c372),
  				GFP_KERNEL);
  	if (!rs5c372) {

  		err = -ENOMEM;
  		goto exit;
  	}

  	rs5c372->client = client;

  	i2c_set_clientdata(client, rs5c372);

  	if (client->dev.of_node)
  		rs5c372->type = (enum rtc_type)
  			of_device_get_match_data(&client->dev);
  	else
  		rs5c372->type = id->driver_data;

  	/* we read registers 0x0f then 0x00-0x0f; skip the first one */
  	rs5c372->regs = &rs5c372->buf[1];

  	rs5c372->smbus = smbus_mode;

  	err = rs5c_get_regs(rs5c372);
  	if (err < 0)

  		goto exit;

  	/* clock may be set for am/pm or 24 hr time */
  	switch (rs5c372->type) {
  	case rtc_rs5c372a:
  	case rtc_rs5c372b:
  		/* alarm uses ALARM_A; and nINTRA on 372a, nINTR on 372b.
  		 * so does periodic irq, except some 327a modes.
  		 */
  		if (rs5c372->regs[RS5C_REG_CTRL2] & RS5C372_CTRL2_24)
  			rs5c372->time24 = 1;
  		break;

  	case rtc_r2025sd:

  	case rtc_r2221tl:

  	case rtc_rv5c386:
  	case rtc_rv5c387a:
  		if (rs5c372->regs[RS5C_REG_CTRL1] & RV5C387_CTRL1_24)
  			rs5c372->time24 = 1;
  		/* alarm uses ALARM_W; and nINTRB for alarm and periodic
  		 * irq, on both 386 and 387
  		 */
  		break;
  	default:
  		dev_err(&client->dev, "unknown RTC type
  ");

  		goto exit;

  	}
  
  	/* if the oscillator lost power and no other software (like
  	 * the bootloader) set it up, do it here.

  	 *
  	 * The R2025S/D does this a little differently than the other
  	 * parts, so we special case that..

  	 */

  	err = rs5c_oscillator_setup(rs5c372);
  	if (unlikely(err < 0)) {
  		dev_err(&client->dev, "setup error
  ");

  		goto exit;

  	}

  	dev_info(&client->dev, "%s found, %s
  ",

  			({ char *s; switch (rs5c372->type) {

  			case rtc_r2025sd:	s = "r2025sd"; break;

  			case rtc_r2221tl:	s = "r2221tl"; break;

  			case rtc_rs5c372a:	s = "rs5c372a"; break;
  			case rtc_rs5c372b:	s = "rs5c372b"; break;
  			case rtc_rv5c386:	s = "rv5c386"; break;
  			case rtc_rv5c387a:	s = "rv5c387a"; break;
  			default:		s = "chip"; break;
  			}; s;}),
  			rs5c372->time24 ? "24hr" : "am/pm"
  			);

  	/* REVISIT use client->irq to register alarm irq ... */

  	rs5c372->rtc = devm_rtc_device_register(&client->dev,
  					rs5c372_driver.driver.name,
  					&rs5c372_rtc_ops, THIS_MODULE);

  	if (IS_ERR(rs5c372->rtc)) {
  		err = PTR_ERR(rs5c372->rtc);

  		goto exit;

  	}

  	err = rs5c_sysfs_register(&client->dev);

  	if (err)

  		goto exit;

  
  	return 0;

  exit:
  	return err;
  }

  static int rs5c372_remove(struct i2c_client *client)

  {

  	rs5c_sysfs_unregister(&client->dev);

  	return 0;
  }

  static struct i2c_driver rs5c372_driver = {
  	.driver		= {
  		.name	= "rtc-rs5c372",

  		.of_match_table = of_match_ptr(rs5c372_of_match),

  	},

  	.probe		= rs5c372_probe,
  	.remove		= rs5c372_remove,

  	.id_table	= rs5c372_id,

  };

  module_i2c_driver(rs5c372_driver);

  
  MODULE_AUTHOR(
  		"Pavel Mironchik <pmironchik@optifacio.net>, "

  		"Alessandro Zummo <a.zummo@towertech.it>, "
  		"Paul Mundt <lethal@linux-sh.org>");

  MODULE_DESCRIPTION("Ricoh RS5C372 RTC driver");
  MODULE_LICENSE("GPL");