/*
   * Dallas DS1302 RTC Support
   *

   *  Copyright (C) 2002 David McCullough
   *  Copyright (C) 2003 - 2007 Paul Mundt

   *
   * This file is subject to the terms and conditions of the GNU General Public

   * License version 2. See the file "COPYING" in the main directory of

   * this archive for more details.
   */

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/platform_device.h>

  #include <linux/rtc.h>

  #include <linux/io.h>
  #include <linux/bcd.h>

  
  #define DRV_NAME	"rtc-ds1302"

  #define DRV_VERSION	"0.1.1"

  
  #define	RTC_CMD_READ	0x81		/* Read command */
  #define	RTC_CMD_WRITE	0x80		/* Write command */

  #define	RTC_CMD_WRITE_ENABLE	0x00		/* Write enable */
  #define	RTC_CMD_WRITE_DISABLE	0x80		/* Write disable */

  #define RTC_ADDR_RAM0	0x20		/* Address of RAM0 */
  #define RTC_ADDR_TCR	0x08		/* Address of trickle charge register */

  #define	RTC_ADDR_CTRL	0x07		/* Address of control register */

  #define	RTC_ADDR_YEAR	0x06		/* Address of year register */
  #define	RTC_ADDR_DAY	0x05		/* Address of day of week register */
  #define	RTC_ADDR_MON	0x04		/* Address of month register */
  #define	RTC_ADDR_DATE	0x03		/* Address of day of month register */
  #define	RTC_ADDR_HOUR	0x02		/* Address of hour register */
  #define	RTC_ADDR_MIN	0x01		/* Address of minute register */
  #define	RTC_ADDR_SEC	0x00		/* Address of second register */

  #ifdef CONFIG_SH_SECUREEDGE5410
  #include <asm/rtc.h>

  #include <mach/secureedge5410.h>

  #define	RTC_RESET	0x1000
  #define	RTC_IODATA	0x0800
  #define	RTC_SCLK	0x0400

  #define set_dp(x)	SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
  #define get_dp()	SECUREEDGE_READ_IOPORT()

  #define ds1302_set_tx()
  #define ds1302_set_rx()
  
  static inline int ds1302_hw_init(void)
  {
  	return 0;
  }
  
  static inline void ds1302_reset(void)
  {
  	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
  }
  
  static inline void ds1302_clock(void)
  {
  	set_dp(get_dp() | RTC_SCLK);	/* clock high */
  	set_dp(get_dp() & ~RTC_SCLK);	/* clock low */
  }
  
  static inline void ds1302_start(void)
  {
  	set_dp(get_dp() | RTC_RESET);
  }
  
  static inline void ds1302_stop(void)
  {
  	set_dp(get_dp() & ~RTC_RESET);
  }
  
  static inline void ds1302_txbit(int bit)
  {
  	set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
  }
  
  static inline int ds1302_rxbit(void)
  {
  	return !!(get_dp() & RTC_IODATA);
  }

  #else
  #error "Add support for your platform"
  #endif

  static void ds1302_sendbits(unsigned int val)
  {
  	int i;

  	ds1302_set_tx();

  	for (i = 8; (i); i--, val >>= 1) {

  		ds1302_txbit(val & 0x1);
  		ds1302_clock();

  	}
  }
  
  static unsigned int ds1302_recvbits(void)
  {
  	unsigned int val;
  	int i;

  	ds1302_set_rx();

  	for (i = 0, val = 0; (i < 8); i++) {

  		val |= (ds1302_rxbit() << i);
  		ds1302_clock();

  	}
  
  	return val;
  }
  
  static unsigned int ds1302_readbyte(unsigned int addr)
  {
  	unsigned int val;

  	ds1302_reset();

  	ds1302_start();

  	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
  	val = ds1302_recvbits();

  	ds1302_stop();

  
  	return val;
  }
  
  static void ds1302_writebyte(unsigned int addr, unsigned int val)
  {

  	ds1302_reset();
  
  	ds1302_start();

  	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
  	ds1302_sendbits(val);

  	ds1302_stop();

  }
  
  static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {

  	tm->tm_sec	= bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
  	tm->tm_min	= bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
  	tm->tm_hour	= bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
  	tm->tm_wday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
  	tm->tm_mday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
  	tm->tm_mon	= bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
  	tm->tm_year	= bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));

  
  	if (tm->tm_year < 70)
  		tm->tm_year += 100;

  	dev_dbg(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 + 1, tm->tm_year, tm->tm_wday);

  	return rtc_valid_tm(tm);

  }
  
  static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {

  	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_ENABLE);

  	/* Stop RTC */
  	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);

  	ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
  	ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
  	ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
  	ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
  	ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
  	ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
  	ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));

  
  	/* Start RTC */
  	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);

  	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_DISABLE);

  	return 0;
  }
  
  static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
  			    unsigned long arg)
  {
  	switch (cmd) {
  #ifdef RTC_SET_CHARGE
  	case RTC_SET_CHARGE:
  	{

  		int tcs_val;
  
  		if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
  			return -EFAULT;

  		ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));

  		return 0;
  	}
  #endif
  	}
  
  	return -ENOIOCTLCMD;
  }
  
  static struct rtc_class_ops ds1302_rtc_ops = {
  	.read_time	= ds1302_rtc_read_time,
  	.set_time	= ds1302_rtc_set_time,
  	.ioctl		= ds1302_rtc_ioctl,
  };

  static int __init ds1302_rtc_probe(struct platform_device *pdev)

  {

  	struct rtc_device *rtc;

  	if (ds1302_hw_init()) {
  		dev_err(&pdev->dev, "Failed to init communication channel");
  		return -EINVAL;
  	}

  	/* Reset */

  	ds1302_reset();

  
  	/* Write a magic value to the DS1302 RAM, and see if it sticks. */
  	ds1302_writebyte(RTC_ADDR_RAM0, 0x42);

  	if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
  		dev_err(&pdev->dev, "Failed to probe");

  		return -ENODEV;

  	}

  	rtc = devm_rtc_device_register(&pdev->dev, "ds1302",

  					   &ds1302_rtc_ops, THIS_MODULE);

  	if (IS_ERR(rtc))
  		return PTR_ERR(rtc);

  
  	platform_set_drvdata(pdev, rtc);
  
  	return 0;

  }

  static struct platform_driver ds1302_platform_driver = {
  	.driver		= {
  		.name	= DRV_NAME,
  		.owner	= THIS_MODULE,
  	},

  };

  module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);

  
  MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
  MODULE_VERSION(DRV_VERSION);
  MODULE_AUTHOR("Paul Mundt, David McCullough");
  MODULE_LICENSE("GPL v2");