/*
   * An rtc driver for the Dallas DS1742
   *
   * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   *
   * 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.

   *
   * Copyright (C) 2006 Torsten Ertbjerg Rasmussen <tr@newtec.dk>
   *  - nvram size determined from resource
   *  - this ds1742 driver now supports ds1743.

   */
  
  #include <linux/bcd.h>
  #include <linux/init.h>
  #include <linux/kernel.h>

  #include <linux/gfp.h>

  #include <linux/delay.h>
  #include <linux/jiffies.h>
  #include <linux/rtc.h>
  #include <linux/platform_device.h>
  #include <linux/io.h>

  #define DRV_VERSION "0.4"

  #define RTC_SIZE		8

  #define RTC_CONTROL		0
  #define RTC_CENTURY		0
  #define RTC_SECONDS		1
  #define RTC_MINUTES		2
  #define RTC_HOURS		3
  #define RTC_DAY			4
  #define RTC_DATE		5
  #define RTC_MONTH		6
  #define RTC_YEAR		7

  
  #define RTC_CENTURY_MASK	0x3f
  #define RTC_SECONDS_MASK	0x7f
  #define RTC_DAY_MASK		0x07
  
  /* Bits in the Control/Century register */
  #define RTC_WRITE		0x80
  #define RTC_READ		0x40
  
  /* Bits in the Seconds register */
  #define RTC_STOP		0x80
  
  /* Bits in the Day register */
  #define RTC_BATT_FLAG		0x80
  
  struct rtc_plat_data {
  	struct rtc_device *rtc;

  	void __iomem *ioaddr_nvram;
  	void __iomem *ioaddr_rtc;
  	size_t size_nvram;
  	size_t size;

  	unsigned long last_jiffies;

  	struct bin_attribute nvram_attr;

  };
  
  static int ds1742_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	void __iomem *ioaddr = pdata->ioaddr_rtc;

  	u8 century;

  	century = bin2bcd((tm->tm_year + 1900) / 100);

  
  	writeb(RTC_WRITE, ioaddr + RTC_CONTROL);

  	writeb(bin2bcd(tm->tm_year % 100), ioaddr + RTC_YEAR);
  	writeb(bin2bcd(tm->tm_mon + 1), ioaddr + RTC_MONTH);
  	writeb(bin2bcd(tm->tm_wday) & RTC_DAY_MASK, ioaddr + RTC_DAY);
  	writeb(bin2bcd(tm->tm_mday), ioaddr + RTC_DATE);
  	writeb(bin2bcd(tm->tm_hour), ioaddr + RTC_HOURS);
  	writeb(bin2bcd(tm->tm_min), ioaddr + RTC_MINUTES);
  	writeb(bin2bcd(tm->tm_sec) & RTC_SECONDS_MASK, ioaddr + RTC_SECONDS);

  
  	/* RTC_CENTURY and RTC_CONTROL share same register */
  	writeb(RTC_WRITE | (century & RTC_CENTURY_MASK), ioaddr + RTC_CENTURY);
  	writeb(century & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  	return 0;
  }
  
  static int ds1742_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	void __iomem *ioaddr = pdata->ioaddr_rtc;

  	unsigned int year, month, day, hour, minute, second, week;
  	unsigned int century;
  
  	/* give enough time to update RTC in case of continuous read */
  	if (pdata->last_jiffies == jiffies)
  		msleep(1);
  	pdata->last_jiffies = jiffies;
  	writeb(RTC_READ, ioaddr + RTC_CONTROL);
  	second = readb(ioaddr + RTC_SECONDS) & RTC_SECONDS_MASK;
  	minute = readb(ioaddr + RTC_MINUTES);
  	hour = readb(ioaddr + RTC_HOURS);
  	day = readb(ioaddr + RTC_DATE);
  	week = readb(ioaddr + RTC_DAY) & RTC_DAY_MASK;
  	month = readb(ioaddr + RTC_MONTH);
  	year = readb(ioaddr + RTC_YEAR);
  	century = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
  	writeb(0, ioaddr + RTC_CONTROL);

  	tm->tm_sec = bcd2bin(second);
  	tm->tm_min = bcd2bin(minute);
  	tm->tm_hour = bcd2bin(hour);
  	tm->tm_mday = bcd2bin(day);
  	tm->tm_wday = bcd2bin(week);
  	tm->tm_mon = bcd2bin(month) - 1;

  	/* year is 1900 + tm->tm_year */

  	tm->tm_year = bcd2bin(year) + bcd2bin(century) * 100 - 1900;

  
  	if (rtc_valid_tm(tm) < 0) {
  		dev_err(dev, "retrieved date/time is not valid.
  ");
  		rtc_time_to_tm(0, tm);
  	}
  	return 0;
  }

  static const struct rtc_class_ops ds1742_rtc_ops = {

  	.read_time	= ds1742_rtc_read_time,
  	.set_time	= ds1742_rtc_set_time,
  };

  static ssize_t ds1742_nvram_read(struct file *filp, struct kobject *kobj,

  				 struct bin_attribute *bin_attr,
  				 char *buf, loff_t pos, size_t size)

  {

  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct platform_device *pdev = to_platform_device(dev);

  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	void __iomem *ioaddr = pdata->ioaddr_nvram;

  	ssize_t count;

  	for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)

  		*buf++ = readb(ioaddr + pos++);
  	return count;
  }

  static ssize_t ds1742_nvram_write(struct file *filp, struct kobject *kobj,

  				  struct bin_attribute *bin_attr,
  				  char *buf, loff_t pos, size_t size)

  {

  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct platform_device *pdev = to_platform_device(dev);

  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	void __iomem *ioaddr = pdata->ioaddr_nvram;

  	ssize_t count;

  	for (count = 0; size > 0 && pos < pdata->size_nvram; count++, size--)

  		writeb(*buf++, ioaddr + pos++);
  	return count;
  }

  static int __devinit ds1742_rtc_probe(struct platform_device *pdev)

  {
  	struct rtc_device *rtc;
  	struct resource *res;
  	unsigned int cen, sec;

  	struct rtc_plat_data *pdata;
  	void __iomem *ioaddr;

  	int ret = 0;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		return -ENODEV;

  	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);

  	if (!pdata)
  		return -ENOMEM;

  	pdata->size = resource_size(res);

  	if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
  		pdev->name))
  		return -EBUSY;
  	ioaddr = devm_ioremap(&pdev->dev, res->start, pdata->size);
  	if (!ioaddr)
  		return -ENOMEM;

  	pdata->ioaddr_nvram = ioaddr;
  	pdata->size_nvram = pdata->size - RTC_SIZE;
  	pdata->ioaddr_rtc = ioaddr + pdata->size_nvram;

  	sysfs_bin_attr_init(&pdata->nvram_attr);

  	pdata->nvram_attr.attr.name = "nvram";
  	pdata->nvram_attr.attr.mode = S_IRUGO | S_IWUSR;
  	pdata->nvram_attr.read = ds1742_nvram_read;
  	pdata->nvram_attr.write = ds1742_nvram_write;
  	pdata->nvram_attr.size = pdata->size_nvram;

  	/* turn RTC on if it was not on */

  	ioaddr = pdata->ioaddr_rtc;

  	sec = readb(ioaddr + RTC_SECONDS);
  	if (sec & RTC_STOP) {
  		sec &= RTC_SECONDS_MASK;
  		cen = readb(ioaddr + RTC_CENTURY) & RTC_CENTURY_MASK;
  		writeb(RTC_WRITE, ioaddr + RTC_CONTROL);
  		writeb(sec, ioaddr + RTC_SECONDS);
  		writeb(cen & RTC_CENTURY_MASK, ioaddr + RTC_CONTROL);
  	}

  	if (!(readb(ioaddr + RTC_DAY) & RTC_BATT_FLAG))

  		dev_warn(&pdev->dev, "voltage-low detected.
  ");

  	pdata->last_jiffies = jiffies;
  	platform_set_drvdata(pdev, pdata);

  	rtc = rtc_device_register(pdev->name, &pdev->dev,
  				  &ds1742_rtc_ops, THIS_MODULE);

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

  	pdata->rtc = rtc;

  
  	ret = sysfs_create_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);
  	if (ret) {
  		dev_err(&pdev->dev, "creating nvram file in sysfs failed
  ");

  		rtc_device_unregister(rtc);

  	}

  	return ret;
  }
  
  static int __devexit ds1742_rtc_remove(struct platform_device *pdev)
  {
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	sysfs_remove_bin_file(&pdev->dev.kobj, &pdata->nvram_attr);

  	rtc_device_unregister(pdata->rtc);

  	return 0;
  }
  
  static struct platform_driver ds1742_rtc_driver = {
  	.probe		= ds1742_rtc_probe,
  	.remove		= __devexit_p(ds1742_rtc_remove),
  	.driver		= {

  		.name	= "rtc-ds1742",

  		.owner	= THIS_MODULE,
  	},
  };
  
  static __init int ds1742_init(void)
  {
  	return platform_driver_register(&ds1742_rtc_driver);
  }
  
  static __exit void ds1742_exit(void)
  {

  	platform_driver_unregister(&ds1742_rtc_driver);

  }
  
  module_init(ds1742_init);
  module_exit(ds1742_exit);
  
  MODULE_AUTHOR("Atsushi Nemoto <anemo@mba.ocn.ne.jp>");
  MODULE_DESCRIPTION("Dallas DS1742 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);

  MODULE_ALIAS("platform:rtc-ds1742");