/*
   * An I2C driver for the Philips PCF8563 RTC
   * Copyright 2005-06 Tower Technologies
   *
   * Author: Alessandro Zummo <a.zummo@towertech.it>
   * Maintainers: http://www.nslu2-linux.org/
   *
   * based on the other drivers in this same directory.
   *
   * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
   *
   * 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>

  #define DRV_VERSION "0.4.3"

  
  #define PCF8563_REG_ST1		0x00 /* status */
  #define PCF8563_REG_ST2		0x01
  
  #define PCF8563_REG_SC		0x02 /* datetime */
  #define PCF8563_REG_MN		0x03
  #define PCF8563_REG_HR		0x04
  #define PCF8563_REG_DM		0x05
  #define PCF8563_REG_DW		0x06
  #define PCF8563_REG_MO		0x07
  #define PCF8563_REG_YR		0x08
  
  #define PCF8563_REG_AMN		0x09 /* alarm */
  #define PCF8563_REG_AHR		0x0A
  #define PCF8563_REG_ADM		0x0B
  #define PCF8563_REG_ADW		0x0C
  
  #define PCF8563_REG_CLKO	0x0D /* clock out */
  #define PCF8563_REG_TMRC	0x0E /* timer control */
  #define PCF8563_REG_TMR		0x0F /* timer */
  
  #define PCF8563_SC_LV		0x80 /* low voltage */
  #define PCF8563_MO_C		0x80 /* century */

  static struct i2c_driver pcf8563_driver;

  struct pcf8563 {

  	struct rtc_device *rtc;

  	/*
  	 * The meaning of MO_C bit varies by the chip type.
  	 * From PCF8563 datasheet: this bit is toggled when the years
  	 * register overflows from 99 to 00
  	 *   0 indicates the century is 20xx
  	 *   1 indicates the century is 19xx
  	 * From RTC8564 datasheet: this bit indicates change of
  	 * century. When the year digit data overflows from 99 to 00,
  	 * this bit is set. By presetting it to 0 while still in the
  	 * 20th century, it will be set in year 2000, ...
  	 * There seems no reliable way to know how the system use this
  	 * bit.  So let's do it heuristically, assuming we are live in
  	 * 1970...2069.
  	 */
  	int c_polarity;	/* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  };

  /*
   * In the routines that deal directly with the pcf8563 hardware, we use
   * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
   */
  static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  {

  	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);

  	unsigned char buf[13] = { PCF8563_REG_ST1 };
  
  	struct i2c_msg msgs[] = {
  		{ client->addr, 0, 1, buf },	/* setup read ptr */
  		{ client->addr, I2C_M_RD, 13, buf },	/* read status + date */
  	};
  
  	/* read registers */
  	if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {

  		dev_err(&client->dev, "%s: read error
  ", __func__);

  		return -EIO;
  	}
  
  	if (buf[PCF8563_REG_SC] & PCF8563_SC_LV)
  		dev_info(&client->dev,
  			"low voltage detected, date/time is not reliable.
  ");
  
  	dev_dbg(&client->dev,
  		"%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
  		"mday=%02x, wday=%02x, mon=%02x, year=%02x
  ",

  		__func__,

  		buf[0], buf[1], buf[2], buf[3],
  		buf[4], buf[5], buf[6], buf[7],
  		buf[8]);
  
  
  	tm->tm_sec = BCD2BIN(buf[PCF8563_REG_SC] & 0x7F);
  	tm->tm_min = BCD2BIN(buf[PCF8563_REG_MN] & 0x7F);
  	tm->tm_hour = BCD2BIN(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
  	tm->tm_mday = BCD2BIN(buf[PCF8563_REG_DM] & 0x3F);
  	tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
  	tm->tm_mon = BCD2BIN(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */

  	tm->tm_year = BCD2BIN(buf[PCF8563_REG_YR]);
  	if (tm->tm_year < 70)
  		tm->tm_year += 100;	/* assume we are in 1970...2069 */
  	/* detect the polarity heuristically. see note above. */
  	pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
  		(tm->tm_year >= 100) : (tm->tm_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);
  
  	/* the clock can give out invalid datetime, but we cannot return
  	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
  	 */
  	if (rtc_valid_tm(tm) < 0)
  		dev_err(&client->dev, "retrieved date/time is not valid.
  ");
  
  	return 0;
  }
  
  static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  {

  	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);

  	int i, err;
  	unsigned char buf[9];
  
  	dev_dbg(&client->dev, "%s: 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);
  
  	/* hours, minutes and seconds */
  	buf[PCF8563_REG_SC] = BIN2BCD(tm->tm_sec);
  	buf[PCF8563_REG_MN] = BIN2BCD(tm->tm_min);
  	buf[PCF8563_REG_HR] = BIN2BCD(tm->tm_hour);
  
  	buf[PCF8563_REG_DM] = BIN2BCD(tm->tm_mday);
  
  	/* month, 1 - 12 */
  	buf[PCF8563_REG_MO] = BIN2BCD(tm->tm_mon + 1);
  
  	/* year and century */
  	buf[PCF8563_REG_YR] = BIN2BCD(tm->tm_year % 100);

  	if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))

  		buf[PCF8563_REG_MO] |= PCF8563_MO_C;
  
  	buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
  
  	/* write register's data */
  	for (i = 0; i < 7; i++) {
  		unsigned char data[2] = { PCF8563_REG_SC + i,
  						buf[PCF8563_REG_SC + i] };
  
  		err = i2c_master_send(client, data, sizeof(data));
  		if (err != sizeof(data)) {
  			dev_err(&client->dev,
  				"%s: err=%d addr=%02x, data=%02x
  ",

  				__func__, err, data[0], data[1]);

  			return -EIO;
  		}
  	};
  
  	return 0;
  }
  
  struct pcf8563_limit
  {
  	unsigned char reg;
  	unsigned char mask;
  	unsigned char min;
  	unsigned char max;
  };
  
  static int pcf8563_validate_client(struct i2c_client *client)
  {
  	int i;
  
  	static const struct pcf8563_limit pattern[] = {
  		/* register, mask, min, max */
  		{ PCF8563_REG_SC,	0x7F,	0,	59	},
  		{ PCF8563_REG_MN,	0x7F,	0,	59	},
  		{ PCF8563_REG_HR,	0x3F,	0,	23	},
  		{ PCF8563_REG_DM,	0x3F,	0,	31	},
  		{ PCF8563_REG_MO,	0x1F,	0,	12	},
  	};
  
  	/* check limits (only registers with bcd values) */
  	for (i = 0; i < ARRAY_SIZE(pattern); i++) {
  		int xfer;
  		unsigned char value;
  		unsigned char buf = pattern[i].reg;
  
  		struct i2c_msg msgs[] = {
  			{ client->addr, 0, 1, &buf },
  			{ client->addr, I2C_M_RD, 1, &buf },
  		};
  
  		xfer = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  
  		if (xfer != ARRAY_SIZE(msgs)) {

  			dev_err(&client->dev,

  				"%s: could not read register 0x%02X
  ",

  				__func__, pattern[i].reg);

  
  			return -EIO;
  		}
  
  		value = BCD2BIN(buf & pattern[i].mask);
  
  		if (value > pattern[i].max ||
  			value < pattern[i].min) {

  			dev_dbg(&client->dev,

  				"%s: pattern=%d, reg=%x, mask=0x%02x, min=%d, "
  				"max=%d, value=%d, raw=0x%02X
  ",

  				__func__, i, pattern[i].reg, pattern[i].mask,

  				pattern[i].min, pattern[i].max,
  				value, buf);
  
  			return -ENODEV;
  		}
  	}
  
  	return 0;
  }
  
  static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf8563_get_datetime(to_i2c_client(dev), tm);
  }
  
  static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf8563_set_datetime(to_i2c_client(dev), tm);
  }

  static const struct rtc_class_ops pcf8563_rtc_ops = {

  	.read_time	= pcf8563_rtc_read_time,
  	.set_time	= pcf8563_rtc_set_time,
  };

  static int pcf8563_probe(struct i2c_client *client,
  				const struct i2c_device_id *id)

  {

  	struct pcf8563 *pcf8563;

  
  	int err = 0;

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

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

  	pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL);
  	if (!pcf8563)
  		return -ENOMEM;

  
  	/* Verify the chip is really an PCF8563 */

  	if (pcf8563_validate_client(client) < 0) {
  		err = -ENODEV;

  		goto exit_kfree;

  	}

  
  	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "
  ");

  	pcf8563->rtc = rtc_device_register(pcf8563_driver.driver.name,
  				&client->dev, &pcf8563_rtc_ops, THIS_MODULE);

  	if (IS_ERR(pcf8563->rtc)) {
  		err = PTR_ERR(pcf8563->rtc);
  		goto exit_kfree;

  	}

  	i2c_set_clientdata(client, pcf8563);

  
  	return 0;

  exit_kfree:

  	kfree(pcf8563);

  	return err;
  }

  static int pcf8563_remove(struct i2c_client *client)

  {

  	struct pcf8563 *pcf8563 = i2c_get_clientdata(client);

  	if (pcf8563->rtc)
  		rtc_device_unregister(pcf8563->rtc);

  	kfree(pcf8563);

  
  	return 0;
  }

  static const struct i2c_device_id pcf8563_id[] = {
  	{ "pcf8563", 0 },

  	{ "rtc8564", 0 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, pcf8563_id);

  static struct i2c_driver pcf8563_driver = {
  	.driver		= {
  		.name	= "rtc-pcf8563",
  	},
  	.probe		= pcf8563_probe,
  	.remove		= pcf8563_remove,

  	.id_table	= pcf8563_id,

  };

  static int __init pcf8563_init(void)
  {
  	return i2c_add_driver(&pcf8563_driver);
  }
  
  static void __exit pcf8563_exit(void)
  {
  	i2c_del_driver(&pcf8563_driver);
  }
  
  MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
  MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);
  
  module_init(pcf8563_init);
  module_exit(pcf8563_exit);