/*
   * An i2c driver for the Xicor/Intersil X1205 RTC
   * Copyright 2004 Karen Spearel
   * Copyright 2005 Alessandro Zummo
   *
   * please send all reports to:
   *	Karen Spearel <kas111 at gmail dot com>
   *	Alessandro Zummo <a.zummo@towertech.it>
   *
   * based on a lot of other RTC drivers.
   *
   * Information and datasheet:
   * http://www.intersil.com/cda/deviceinfo/0,1477,X1205,00.html
   *
   * 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/i2c.h>
  #include <linux/bcd.h>
  #include <linux/rtc.h>
  #include <linux/delay.h>
  #include <linux/module.h>
  
  #define DRV_VERSION "1.0.8"
  
  /* offsets into CCR area */
  
  #define CCR_SEC			0
  #define CCR_MIN			1
  #define CCR_HOUR		2
  #define CCR_MDAY		3
  #define CCR_MONTH		4
  #define CCR_YEAR		5
  #define CCR_WDAY		6
  #define CCR_Y2K			7
  
  #define X1205_REG_SR		0x3F	/* status register */
  #define X1205_REG_Y2K		0x37
  #define X1205_REG_DW		0x36
  #define X1205_REG_YR		0x35
  #define X1205_REG_MO		0x34
  #define X1205_REG_DT		0x33
  #define X1205_REG_HR		0x32
  #define X1205_REG_MN		0x31
  #define X1205_REG_SC		0x30
  #define X1205_REG_DTR		0x13
  #define X1205_REG_ATR		0x12
  #define X1205_REG_INT		0x11
  #define X1205_REG_0		0x10
  #define X1205_REG_Y2K1		0x0F
  #define X1205_REG_DWA1		0x0E
  #define X1205_REG_YRA1		0x0D
  #define X1205_REG_MOA1		0x0C
  #define X1205_REG_DTA1		0x0B
  #define X1205_REG_HRA1		0x0A
  #define X1205_REG_MNA1		0x09
  #define X1205_REG_SCA1		0x08
  #define X1205_REG_Y2K0		0x07
  #define X1205_REG_DWA0		0x06
  #define X1205_REG_YRA0		0x05
  #define X1205_REG_MOA0		0x04
  #define X1205_REG_DTA0		0x03
  #define X1205_REG_HRA0		0x02
  #define X1205_REG_MNA0		0x01
  #define X1205_REG_SCA0		0x00
  
  #define X1205_CCR_BASE		0x30	/* Base address of CCR */
  #define X1205_ALM0_BASE		0x00	/* Base address of ALARM0 */
  
  #define X1205_SR_RTCF		0x01	/* Clock failure */
  #define X1205_SR_WEL		0x02	/* Write Enable Latch */
  #define X1205_SR_RWEL		0x04	/* Register Write Enable */
  #define X1205_SR_AL0		0x20	/* Alarm 0 match */
  
  #define X1205_DTR_DTR0		0x01
  #define X1205_DTR_DTR1		0x02
  #define X1205_DTR_DTR2		0x04
  
  #define X1205_HR_MIL		0x80	/* Set in ccr.hour for 24 hr mode */
  
  #define X1205_INT_AL0E		0x20	/* Alarm 0 enable */
  
  static struct i2c_driver x1205_driver;
  
  /*
   * In the routines that deal directly with the x1205 hardware, we use
   * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
   * Epoch is initialized as 2000. Time is set to UTC.
   */
  static int x1205_get_datetime(struct i2c_client *client, struct rtc_time *tm,
  				unsigned char reg_base)
  {
  	unsigned char dt_addr[2] = { 0, reg_base };
  	unsigned char buf[8];
  	int i;
  
  	struct i2c_msg msgs[] = {
  		{/* setup read ptr */
  			.addr = client->addr,
  			.len = 2,
  			.buf = dt_addr
  		},
  		{/* read date */
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = 8,
  			.buf = buf
  		},
  	};
  
  	/* read date registers */
  	if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  
  	dev_dbg(&client->dev,
  		"%s: raw read data - sec=%02x, min=%02x, hr=%02x, "
  		"mday=%02x, mon=%02x, year=%02x, wday=%02x, y2k=%02x
  ",
  		__func__,
  		buf[0], buf[1], buf[2], buf[3],
  		buf[4], buf[5], buf[6], buf[7]);
  
  	/* Mask out the enable bits if these are alarm registers */
  	if (reg_base < X1205_CCR_BASE)
  		for (i = 0; i <= 4; i++)
  			buf[i] &= 0x7F;
  
  	tm->tm_sec = bcd2bin(buf[CCR_SEC]);
  	tm->tm_min = bcd2bin(buf[CCR_MIN]);
  	tm->tm_hour = bcd2bin(buf[CCR_HOUR] & 0x3F); /* hr is 0-23 */
  	tm->tm_mday = bcd2bin(buf[CCR_MDAY]);
  	tm->tm_mon = bcd2bin(buf[CCR_MONTH]) - 1; /* mon is 0-11 */
  	tm->tm_year = bcd2bin(buf[CCR_YEAR])
  			+ (bcd2bin(buf[CCR_Y2K]) * 100) - 1900;
  	tm->tm_wday = buf[CCR_WDAY];
  
  	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 x1205_get_status(struct i2c_client *client, unsigned char *sr)
  {
  	static unsigned char sr_addr[2] = { 0, X1205_REG_SR };
  
  	struct i2c_msg msgs[] = {
  		{     /* setup read ptr */
  			.addr = client->addr,
  			.len = 2,
  			.buf = sr_addr
  		},
  		{    /* read status */
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = 1,
  			.buf = sr
  		},
  	};
  
  	/* read status register */
  	if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static int x1205_set_datetime(struct i2c_client *client, struct rtc_time *tm,
  			u8 reg_base, unsigned char alm_enable)
  {
  	int i, xfer;
  	unsigned char rdata[10] = { 0, reg_base };
  	unsigned char *buf = rdata + 2;
  
  	static const unsigned char wel[3] = { 0, X1205_REG_SR,
  						X1205_SR_WEL };
  
  	static const unsigned char rwel[3] = { 0, X1205_REG_SR,
  						X1205_SR_WEL | X1205_SR_RWEL };
  
  	static const unsigned char diswe[3] = { 0, X1205_REG_SR, 0 };
  
  	dev_dbg(&client->dev,
  		"%s: sec=%d min=%d hour=%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);
  
  	buf[CCR_SEC] = bin2bcd(tm->tm_sec);
  	buf[CCR_MIN] = bin2bcd(tm->tm_min);
  
  	/* set hour and 24hr bit */
  	buf[CCR_HOUR] = bin2bcd(tm->tm_hour) | X1205_HR_MIL;
  
  	buf[CCR_MDAY] = bin2bcd(tm->tm_mday);
  
  	/* month, 1 - 12 */
  	buf[CCR_MONTH] = bin2bcd(tm->tm_mon + 1);
  
  	/* year, since the rtc epoch*/
  	buf[CCR_YEAR] = bin2bcd(tm->tm_year % 100);
  	buf[CCR_WDAY] = tm->tm_wday & 0x07;
  	buf[CCR_Y2K] = bin2bcd((tm->tm_year + 1900) / 100);
  
  	/* If writing alarm registers, set compare bits on registers 0-4 */
  	if (reg_base < X1205_CCR_BASE)
  		for (i = 0; i <= 4; i++)
  			buf[i] |= 0x80;
  
  	/* this sequence is required to unlock the chip */
  	xfer = i2c_master_send(client, wel, 3);
  	if (xfer != 3) {
  		dev_err(&client->dev, "%s: wel - %d
  ", __func__, xfer);
  		return -EIO;
  	}
  
  	xfer = i2c_master_send(client, rwel, 3);
  	if (xfer != 3) {
  		dev_err(&client->dev, "%s: rwel - %d
  ", __func__, xfer);
  		return -EIO;
  	}
  
  	xfer = i2c_master_send(client, rdata, sizeof(rdata));
  	if (xfer != sizeof(rdata)) {
  		dev_err(&client->dev,
  			"%s: result=%d addr=%02x, data=%02x
  ",
  			__func__,
  			 xfer, rdata[1], rdata[2]);
  		return -EIO;
  	}
  
  	/* If we wrote to the nonvolatile region, wait 10msec for write cycle*/
  	if (reg_base < X1205_CCR_BASE) {
  		unsigned char al0e[3] = { 0, X1205_REG_INT, 0 };
  
  		msleep(10);
  
  		/* ...and set or clear the AL0E bit in the INT register */
  
  		/* Need to set RWEL again as the write has cleared it */
  		xfer = i2c_master_send(client, rwel, 3);
  		if (xfer != 3) {
  			dev_err(&client->dev,
  				"%s: aloe rwel - %d
  ",
  				__func__,
  				xfer);
  			return -EIO;
  		}
  
  		if (alm_enable)
  			al0e[2] = X1205_INT_AL0E;
  
  		xfer = i2c_master_send(client, al0e, 3);
  		if (xfer != 3) {
  			dev_err(&client->dev,
  				"%s: al0e - %d
  ",
  				__func__,
  				xfer);
  			return -EIO;
  		}
  
  		/* and wait 10msec again for this write to complete */
  		msleep(10);
  	}
  
  	/* disable further writes */
  	xfer = i2c_master_send(client, diswe, 3);
  	if (xfer != 3) {
  		dev_err(&client->dev, "%s: diswe - %d
  ", __func__, xfer);
  		return -EIO;
  	}
  
  	return 0;
  }
  
  static int x1205_fix_osc(struct i2c_client *client)
  {
  	int err;
  	struct rtc_time tm;
  
  	memset(&tm, 0, sizeof(tm));
  
  	err = x1205_set_datetime(client, &tm, X1205_CCR_BASE, 0);
  	if (err < 0)
  		dev_err(&client->dev, "unable to restart the oscillator
  ");
  
  	return err;
  }
  
  static int x1205_get_dtrim(struct i2c_client *client, int *trim)
  {
  	unsigned char dtr;
  	static unsigned char dtr_addr[2] = { 0, X1205_REG_DTR };
  
  	struct i2c_msg msgs[] = {
  		{	/* setup read ptr */
  			.addr = client->addr,
  			.len = 2,
  			.buf = dtr_addr
  		},
  		{      /* read dtr */
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = 1,
  			.buf = &dtr
  		},
  	};
  
  	/* read dtr register */
  	if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  
  	dev_dbg(&client->dev, "%s: raw dtr=%x
  ", __func__, dtr);
  
  	*trim = 0;
  
  	if (dtr & X1205_DTR_DTR0)
  		*trim += 20;
  
  	if (dtr & X1205_DTR_DTR1)
  		*trim += 10;
  
  	if (dtr & X1205_DTR_DTR2)
  		*trim = -*trim;
  
  	return 0;
  }
  
  static int x1205_get_atrim(struct i2c_client *client, int *trim)
  {
  	s8 atr;
  	static unsigned char atr_addr[2] = { 0, X1205_REG_ATR };
  
  	struct i2c_msg msgs[] = {
  		{/* setup read ptr */
  			.addr = client->addr,
  			.len = 2,
  			.buf = atr_addr
  		},
  		{/* read atr */
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = 1,
  			.buf = &atr
  		},
  	};
  
  	/* read atr register */
  	if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  
  	dev_dbg(&client->dev, "%s: raw atr=%x
  ", __func__, atr);
  
  	/* atr is a two's complement value on 6 bits,
  	 * perform sign extension. The formula is
  	 * Catr = (atr * 0.25pF) + 11.00pF.
  	 */
  	if (atr & 0x20)
  		atr |= 0xC0;
  
  	dev_dbg(&client->dev, "%s: raw atr=%x (%d)
  ", __func__, atr, atr);
  
  	*trim = (atr * 250) + 11000;
  
  	dev_dbg(&client->dev, "%s: real=%d
  ", __func__, *trim);
  
  	return 0;
  }
  
  struct x1205_limit {
  	unsigned char reg, mask, min, max;
  };
  
  static int x1205_validate_client(struct i2c_client *client)
  {
  	int i, xfer;
  
  	/* Probe array. We will read the register at the specified
  	 * address and check if the given bits are zero.
  	 */
  	static const unsigned char probe_zero_pattern[] = {
  		/* register, mask */
  		X1205_REG_SR,	0x18,
  		X1205_REG_DTR,	0xF8,
  		X1205_REG_ATR,	0xC0,
  		X1205_REG_INT,	0x18,
  		X1205_REG_0,	0xFF,
  	};
  
  	static const struct x1205_limit probe_limits_pattern[] = {
  		/* register, mask, min, max */
  		{ X1205_REG_Y2K,	0xFF,	19,	20	},
  		{ X1205_REG_DW,		0xFF,	0,	6	},
  		{ X1205_REG_YR,		0xFF,	0,	99	},
  		{ X1205_REG_MO,		0xFF,	0,	12	},
  		{ X1205_REG_DT,		0xFF,	0,	31	},
  		{ X1205_REG_HR,		0x7F,	0,	23	},
  		{ X1205_REG_MN,		0xFF,	0,	59	},
  		{ X1205_REG_SC,		0xFF,	0,	59	},
  		{ X1205_REG_Y2K1,	0xFF,	19,	20	},
  		{ X1205_REG_Y2K0,	0xFF,	19,	20	},
  	};
  
  	/* check that registers have bits a 0 where expected */
  	for (i = 0; i < ARRAY_SIZE(probe_zero_pattern); i += 2) {
  		unsigned char buf;
  
  		unsigned char addr[2] = { 0, probe_zero_pattern[i] };
  
  		struct i2c_msg msgs[2] = {
  			{
  				.addr = client->addr,
  				.len = 2,
  				.buf = addr
  			},
  			{
  				.addr = client->addr,
  				.flags = I2C_M_RD,
  				.len = 1,
  				.buf = &buf
  			},
  		};
  
  		xfer = i2c_transfer(client->adapter, msgs, 2);
  		if (xfer != 2) {
  			dev_err(&client->dev,
  				"%s: could not read register %x
  ",
  				__func__, probe_zero_pattern[i]);
  
  			return -EIO;
  		}
  
  		if ((buf & probe_zero_pattern[i+1]) != 0) {
  			dev_err(&client->dev,
  				"%s: register=%02x, zero pattern=%d, value=%x
  ",
  				__func__, probe_zero_pattern[i], i, buf);
  
  			return -ENODEV;
  		}
  	}
  
  	/* check limits (only registers with bcd values) */
  	for (i = 0; i < ARRAY_SIZE(probe_limits_pattern); i++) {
  		unsigned char reg, value;
  
  		unsigned char addr[2] = { 0, probe_limits_pattern[i].reg };
  
  		struct i2c_msg msgs[2] = {
  			{
  				.addr = client->addr,
  				.len = 2,
  				.buf = addr
  			},
  			{
  				.addr = client->addr,
  				.flags = I2C_M_RD,
  				.len = 1,
  				.buf = &reg
  			},
  		};
  
  		xfer = i2c_transfer(client->adapter, msgs, 2);
  		if (xfer != 2) {
  			dev_err(&client->dev,
  				"%s: could not read register %x
  ",
  				__func__, probe_limits_pattern[i].reg);
  
  			return -EIO;
  		}
  
  		value = bcd2bin(reg & probe_limits_pattern[i].mask);
  
  		if (value > probe_limits_pattern[i].max ||
  			value < probe_limits_pattern[i].min) {
  			dev_dbg(&client->dev,
  				"%s: register=%x, lim pattern=%d, value=%d
  ",
  				__func__, probe_limits_pattern[i].reg,
  				i, value);
  
  			return -ENODEV;
  		}
  	}
  
  	return 0;
  }
  
  static int x1205_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	int err;
  	unsigned char intreg, status;
  	static unsigned char int_addr[2] = { 0, X1205_REG_INT };
  	struct i2c_client *client = to_i2c_client(dev);
  	struct i2c_msg msgs[] = {
  		{ /* setup read ptr */
  			.addr = client->addr,
  			.len = 2,
  			.buf = int_addr
  		},
  		{/* read INT register */
  
  			.addr = client->addr,
  			.flags = I2C_M_RD,
  			.len = 1,
  			.buf = &intreg
  		},
  	};
  
  	/* read interrupt register and status register */
  	if (i2c_transfer(client->adapter, &msgs[0], 2) != 2) {
  		dev_err(&client->dev, "%s: read error
  ", __func__);
  		return -EIO;
  	}
  	err = x1205_get_status(client, &status);
  	if (err == 0) {
  		alrm->pending = (status & X1205_SR_AL0) ? 1 : 0;
  		alrm->enabled = (intreg & X1205_INT_AL0E) ? 1 : 0;
  		err = x1205_get_datetime(client, &alrm->time, X1205_ALM0_BASE);
  	}
  	return err;
  }
  
  static int x1205_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	return x1205_set_datetime(to_i2c_client(dev),
  		&alrm->time, X1205_ALM0_BASE, alrm->enabled);
  }
  
  static int x1205_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	return x1205_get_datetime(to_i2c_client(dev),
  		tm, X1205_CCR_BASE);
  }
  
  static int x1205_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	return x1205_set_datetime(to_i2c_client(dev),
  		tm, X1205_CCR_BASE, 0);
  }
  
  static int x1205_rtc_proc(struct device *dev, struct seq_file *seq)
  {
  	int err, dtrim, atrim;
  
  	err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
  	if (!err)
  		seq_printf(seq, "digital_trim\t: %d ppm
  ", dtrim);
  
  	err = x1205_get_atrim(to_i2c_client(dev), &atrim);
  	if (!err)
  		seq_printf(seq, "analog_trim\t: %d.%02d pF
  ",
  			atrim / 1000, atrim % 1000);
  	return 0;
  }
  
  static const struct rtc_class_ops x1205_rtc_ops = {
  	.proc		= x1205_rtc_proc,
  	.read_time	= x1205_rtc_read_time,
  	.set_time	= x1205_rtc_set_time,
  	.read_alarm	= x1205_rtc_read_alarm,
  	.set_alarm	= x1205_rtc_set_alarm,
  };
  
  static ssize_t x1205_sysfs_show_atrim(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	int err, atrim;
  
  	err = x1205_get_atrim(to_i2c_client(dev), &atrim);
  	if (err)
  		return err;
  
  	return sprintf(buf, "%d.%02d pF
  ", atrim / 1000, atrim % 1000);
  }
  static DEVICE_ATTR(atrim, S_IRUGO, x1205_sysfs_show_atrim, NULL);
  
  static ssize_t x1205_sysfs_show_dtrim(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	int err, dtrim;
  
  	err = x1205_get_dtrim(to_i2c_client(dev), &dtrim);
  	if (err)
  		return err;
  
  	return sprintf(buf, "%d ppm
  ", dtrim);
  }
  static DEVICE_ATTR(dtrim, S_IRUGO, x1205_sysfs_show_dtrim, NULL);
  
  static int x1205_sysfs_register(struct device *dev)
  {
  	int err;
  
  	err = device_create_file(dev, &dev_attr_atrim);
  	if (err)
  		return err;
  
  	err = device_create_file(dev, &dev_attr_dtrim);
  	if (err)
  		device_remove_file(dev, &dev_attr_atrim);
  
  	return err;
  }
  
  static void x1205_sysfs_unregister(struct device *dev)
  {
  	device_remove_file(dev, &dev_attr_atrim);
  	device_remove_file(dev, &dev_attr_dtrim);
  }
  
  
  static int x1205_probe(struct i2c_client *client,
  			const struct i2c_device_id *id)
  {
  	int err = 0;
  	unsigned char sr;
  	struct rtc_device *rtc;
  
  	dev_dbg(&client->dev, "%s
  ", __func__);
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  		return -ENODEV;
  
  	if (x1205_validate_client(client) < 0)
  		return -ENODEV;
  
  	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "
  ");
  
  	rtc = devm_rtc_device_register(&client->dev, x1205_driver.driver.name,
  					&x1205_rtc_ops, THIS_MODULE);
  
  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);
  
  	i2c_set_clientdata(client, rtc);
  
  	/* Check for power failures and eventually enable the osc */
  	err = x1205_get_status(client, &sr);
  	if (!err) {
  		if (sr & X1205_SR_RTCF) {
  			dev_err(&client->dev,
  				"power failure detected, "
  				"please set the clock
  ");
  			udelay(50);
  			x1205_fix_osc(client);
  		}
  	} else {
  		dev_err(&client->dev, "couldn't read status
  ");
  	}
  
  	err = x1205_sysfs_register(&client->dev);
  	if (err)
  		return err;
  
  	return 0;
  }
  
  static int x1205_remove(struct i2c_client *client)
  {
  	x1205_sysfs_unregister(&client->dev);
  	return 0;
  }
  
  static const struct i2c_device_id x1205_id[] = {
  	{ "x1205", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, x1205_id);
  
  static struct i2c_driver x1205_driver = {
  	.driver		= {
  		.name	= "rtc-x1205",
  	},
  	.probe		= x1205_probe,
  	.remove		= x1205_remove,
  	.id_table	= x1205_id,
  };
  
  module_i2c_driver(x1205_driver);
  
  MODULE_AUTHOR(
  	"Karen Spearel <kas111 at gmail dot com>, "
  	"Alessandro Zummo <a.zummo@towertech.it>");
  MODULE_DESCRIPTION("Xicor/Intersil X1205 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);