/* drivers/rtc/rtc-max6902.c

   *
   * Copyright (C) 2006 8D Technologies inc.
   * Copyright (C) 2004 Compulab Ltd.
   *
   * 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.
   *
   * Driver for MAX6902 spi RTC
   *

   */

  #include <linux/module.h>

  #include <linux/kernel.h>
  #include <linux/platform_device.h>
  #include <linux/init.h>
  #include <linux/rtc.h>
  #include <linux/spi/spi.h>
  #include <linux/bcd.h>

  
  #define MAX6902_REG_SECONDS		0x01
  #define MAX6902_REG_MINUTES		0x03
  #define MAX6902_REG_HOURS		0x05
  #define MAX6902_REG_DATE		0x07
  #define MAX6902_REG_MONTH		0x09
  #define MAX6902_REG_DAY			0x0B
  #define MAX6902_REG_YEAR		0x0D
  #define MAX6902_REG_CONTROL		0x0F
  #define MAX6902_REG_CENTURY		0x13

  static int max6902_set_reg(struct device *dev, unsigned char address,

  				unsigned char data)
  {
  	struct spi_device *spi = to_spi_device(dev);
  	unsigned char buf[2];
  
  	/* MSB must be '0' to write */
  	buf[0] = address & 0x7f;
  	buf[1] = data;

  	return spi_write_then_read(spi, buf, 2, NULL, 0);

  }
  
  static int max6902_get_reg(struct device *dev, unsigned char address,
  				unsigned char *data)
  {
  	struct spi_device *spi = to_spi_device(dev);

  
  	/* Set MSB to indicate read */

  	*data = address | 0x80;

  	return spi_write_then_read(spi, data, 1, data, 1);

  }

  static int max6902_read_time(struct device *dev, struct rtc_time *dt)

  {

  	int err, century;

  	struct spi_device *spi = to_spi_device(dev);

  	unsigned char buf[8];

  	buf[0] = 0xbf;	/* Burst read */

  	err = spi_write_then_read(spi, buf, 1, buf, 8);
  	if (err != 0)
  		return err;

  
  	/* The chip sends data in this order:
  	 * Seconds, Minutes, Hours, Date, Month, Day, Year */

  	dt->tm_sec	= bcd2bin(buf[0]);
  	dt->tm_min	= bcd2bin(buf[1]);
  	dt->tm_hour	= bcd2bin(buf[2]);
  	dt->tm_mday	= bcd2bin(buf[3]);
  	dt->tm_mon	= bcd2bin(buf[4]) - 1;
  	dt->tm_wday	= bcd2bin(buf[5]);
  	dt->tm_year	= bcd2bin(buf[6]);
  
  	/* Read century */
  	err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);
  	if (err != 0)
  		return err;

  	century = bcd2bin(buf[0]) * 100;

  
  	dt->tm_year += century;
  	dt->tm_year -= 1900;

  	return rtc_valid_tm(dt);

  }

  static int max6902_set_time(struct device *dev, struct rtc_time *dt)

  {

  	dt->tm_year = dt->tm_year + 1900;

  
  	/* Remove write protection */
  	max6902_set_reg(dev, 0xF, 0);

  	max6902_set_reg(dev, 0x01, bin2bcd(dt->tm_sec));
  	max6902_set_reg(dev, 0x03, bin2bcd(dt->tm_min));
  	max6902_set_reg(dev, 0x05, bin2bcd(dt->tm_hour));

  	max6902_set_reg(dev, 0x07, bin2bcd(dt->tm_mday));

  	max6902_set_reg(dev, 0x09, bin2bcd(dt->tm_mon + 1));

  	max6902_set_reg(dev, 0x0B, bin2bcd(dt->tm_wday));

  	max6902_set_reg(dev, 0x0D, bin2bcd(dt->tm_year % 100));
  	max6902_set_reg(dev, 0x13, bin2bcd(dt->tm_year / 100));

  
  	/* Compulab used a delay here. However, the datasheet
  	 * does not mention a delay being required anywhere... */
  	/* delay(2000); */
  
  	/* Write protect */
  	max6902_set_reg(dev, 0xF, 0x80);
  
  	return 0;
  }

  static const struct rtc_class_ops max6902_rtc_ops = {

  	.read_time	= max6902_read_time,
  	.set_time	= max6902_set_time,
  };
  
  static int __devinit max6902_probe(struct spi_device *spi)
  {
  	struct rtc_device *rtc;
  	unsigned char tmp;

  	int res;

  	spi->mode = SPI_MODE_3;
  	spi->bits_per_word = 8;
  	spi_setup(spi);

  	res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);

  	if (res != 0)

  		return res;

  
  	rtc = rtc_device_register("max6902",
  				&spi->dev, &max6902_rtc_ops, THIS_MODULE);
  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);

  	dev_set_drvdata(&spi->dev, rtc);

  	return 0;
  }
  
  static int __devexit max6902_remove(struct spi_device *spi)
  {

  	struct rtc_device *rtc = dev_get_drvdata(&spi->dev);

  	rtc_device_unregister(rtc);

  	return 0;
  }
  
  static struct spi_driver max6902_driver = {
  	.driver = {

  		.name	= "rtc-max6902",

  		.owner	= THIS_MODULE,
  	},

  	.probe	= max6902_probe,

  	.remove = __devexit_p(max6902_remove),
  };
  
  static __init int max6902_init(void)
  {

  	return spi_register_driver(&max6902_driver);
  }
  module_init(max6902_init);
  
  static __exit void max6902_exit(void)
  {
  	spi_unregister_driver(&max6902_driver);
  }
  module_exit(max6902_exit);
  
  MODULE_DESCRIPTION ("max6902 spi RTC driver");
  MODULE_AUTHOR ("Raphael Assenat");
  MODULE_LICENSE ("GPL");

  MODULE_ALIAS("spi:rtc-max6902");