/*
   * An I2C driver for the PCF85063 RTC
   * Copyright 2014 Rose Technology
   *
   * Author: Søren Andersen <san@rosetechnology.dk>
   * Maintainers: http://www.nslu2-linux.org/
   *
   * based on the other drivers in this same directory.
   *
   * 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/module.h>

  /*
   * Information for this driver was pulled from the following datasheets.
   *
   *  http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
   *  http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
   *
   *  PCF85063A -- Rev. 6 — 18 November 2015
   *  PCF85063TP -- Rev. 4 — 6 May 2015
  */

  #define PCF85063_REG_CTRL1		0x00 /* status */

  #define PCF85063_REG_CTRL1_STOP		BIT(5)

  #define PCF85063_REG_CTRL2		0x01
  
  #define PCF85063_REG_SC			0x04 /* datetime */

  #define PCF85063_REG_SC_OS		0x80

  #define PCF85063_REG_MN			0x05
  #define PCF85063_REG_HR			0x06
  #define PCF85063_REG_DM			0x07
  #define PCF85063_REG_DW			0x08
  #define PCF85063_REG_MO			0x09
  #define PCF85063_REG_YR			0x0A

  static struct i2c_driver pcf85063_driver;

  static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
  {
  	s32 ret;
  
  	ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
  	if (ret < 0) {
  		dev_err(&client->dev, "Failing to stop the clock
  ");
  		return -EIO;
  	}
  
  	/* stop the clock */
  	ret |= PCF85063_REG_CTRL1_STOP;
  
  	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
  	if (ret < 0) {
  		dev_err(&client->dev, "Failing to stop the clock
  ");
  		return -EIO;
  	}
  
  	*ctrl1 = ret;
  
  	return 0;
  }

  static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
  {
  	s32 ret;
  
  	/* start the clock */
  	ctrl1 &= PCF85063_REG_CTRL1_STOP;
  
  	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
  	if (ret < 0) {
  		dev_err(&client->dev, "Failing to start the clock
  ");
  		return -EIO;
  	}
  
  	return 0;
  }

  static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  {

  	int rc;

  	u8 regs[7];
  
  	/*
  	 * while reading, the time/date registers are blocked and not updated
  	 * anymore until the access is finished. To not lose a second
  	 * event, the access must be finished within one second. So, read all
  	 * time/date registers in one turn.
  	 */
  	rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
  					   sizeof(regs), regs);
  	if (rc != sizeof(regs)) {
  		dev_err(&client->dev, "date/time register read error
  ");

  		return -EIO;
  	}

  	/* if the clock has lost its power it makes no sense to use its time */
  	if (regs[0] & PCF85063_REG_SC_OS) {
  		dev_warn(&client->dev, "Power loss detected, invalid time
  ");
  		return -EINVAL;
  	}

  	tm->tm_sec = bcd2bin(regs[0] & 0x7F);
  	tm->tm_min = bcd2bin(regs[1] & 0x7F);
  	tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
  	tm->tm_mday = bcd2bin(regs[3] & 0x3F);
  	tm->tm_wday = regs[4] & 0x07;
  	tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
  	tm->tm_year = bcd2bin(regs[6]);

  	tm->tm_year += 100;

  	return rtc_valid_tm(tm);

  }
  
  static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  {

  	int rc;

  	u8 regs[7];
  	u8 ctrl1;

  	if ((tm->tm_year < 100) || (tm->tm_year > 199))
  		return -EINVAL;

  	/*
  	 * to accurately set the time, reset the divider chain and keep it in
  	 * reset state until all time/date registers are written
  	 */

  	rc = pcf85063_stop_clock(client, &ctrl1);

  	if (rc != 0)
  		return rc;

  
  	/* hours, minutes and seconds */

  	regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */

  	regs[1] = bin2bcd(tm->tm_min);
  	regs[2] = bin2bcd(tm->tm_hour);

  
  	/* Day of month, 1 - 31 */

  	regs[3] = bin2bcd(tm->tm_mday);

  
  	/* Day, 0 - 6 */

  	regs[4] = tm->tm_wday & 0x07;

  
  	/* month, 1 - 12 */

  	regs[5] = bin2bcd(tm->tm_mon + 1);

  
  	/* year and century */

  	regs[6] = bin2bcd(tm->tm_year - 100);

  	/* write all registers at once */
  	rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
  					    sizeof(regs), regs);
  	if (rc < 0) {
  		dev_err(&client->dev, "date/time register write error
  ");
  		return rc;

  	}

  	/*
  	 * Write the control register as a separate action since the size of
  	 * the register space is different between the PCF85063TP and
  	 * PCF85063A devices.  The rollover point can not be used.
  	 */
  	rc = pcf85063_start_clock(client, ctrl1);
  	if (rc != 0)
  		return rc;

  	return 0;
  }
  
  static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf85063_get_datetime(to_i2c_client(dev), tm);
  }
  
  static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	return pcf85063_set_datetime(to_i2c_client(dev), tm);
  }
  
  static const struct rtc_class_ops pcf85063_rtc_ops = {
  	.read_time	= pcf85063_rtc_read_time,
  	.set_time	= pcf85063_rtc_set_time
  };
  
  static int pcf85063_probe(struct i2c_client *client,
  				const struct i2c_device_id *id)
  {

  	struct rtc_device *rtc;

  
  	dev_dbg(&client->dev, "%s
  ", __func__);
  
  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  		return -ENODEV;

  	rtc = devm_rtc_device_register(&client->dev,
  				       pcf85063_driver.driver.name,
  				       &pcf85063_rtc_ops, THIS_MODULE);

  	return PTR_ERR_OR_ZERO(rtc);

  }
  
  static const struct i2c_device_id pcf85063_id[] = {
  	{ "pcf85063", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, pcf85063_id);
  
  #ifdef CONFIG_OF
  static const struct of_device_id pcf85063_of_match[] = {
  	{ .compatible = "nxp,pcf85063" },
  	{}
  };
  MODULE_DEVICE_TABLE(of, pcf85063_of_match);
  #endif
  
  static struct i2c_driver pcf85063_driver = {
  	.driver		= {
  		.name	= "rtc-pcf85063",

  		.of_match_table = of_match_ptr(pcf85063_of_match),
  	},
  	.probe		= pcf85063_probe,
  	.id_table	= pcf85063_id,
  };
  
  module_i2c_driver(pcf85063_driver);
  
  MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
  MODULE_DESCRIPTION("PCF85063 RTC driver");
  MODULE_LICENSE("GPL");