/*
   * An rtc driver for the Dallas DS1511
   *
   * Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>

   * Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>

   *
   * 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.
   *
   * Real time clock driver for the Dallas 1511 chip, which also
   * contains a watchdog timer.  There is a tiny amount of code that
   * platform code could use to mess with the watchdog device a little
   * bit, but not a full watchdog driver.
   */
  
  #include <linux/bcd.h>
  #include <linux/init.h>
  #include <linux/kernel.h>

  #include <linux/gfp.h>

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

  #include <linux/module.h>

  
  #define DRV_VERSION "0.6"
  
  enum ds1511reg {
  	DS1511_SEC = 0x0,
  	DS1511_MIN = 0x1,
  	DS1511_HOUR = 0x2,
  	DS1511_DOW = 0x3,
  	DS1511_DOM = 0x4,
  	DS1511_MONTH = 0x5,
  	DS1511_YEAR = 0x6,
  	DS1511_CENTURY = 0x7,
  	DS1511_AM1_SEC = 0x8,
  	DS1511_AM2_MIN = 0x9,
  	DS1511_AM3_HOUR = 0xa,
  	DS1511_AM4_DATE = 0xb,
  	DS1511_WD_MSEC = 0xc,
  	DS1511_WD_SEC = 0xd,
  	DS1511_CONTROL_A = 0xe,
  	DS1511_CONTROL_B = 0xf,
  	DS1511_RAMADDR_LSB = 0x10,
  	DS1511_RAMDATA = 0x13
  };
  
  #define DS1511_BLF1	0x80
  #define DS1511_BLF2	0x40
  #define DS1511_PRS	0x20
  #define DS1511_PAB	0x10
  #define DS1511_TDF	0x08
  #define DS1511_KSF	0x04
  #define DS1511_WDF	0x02
  #define DS1511_IRQF	0x01
  #define DS1511_TE	0x80
  #define DS1511_CS	0x40
  #define DS1511_BME	0x20
  #define DS1511_TPE	0x10
  #define DS1511_TIE	0x08
  #define DS1511_KIE	0x04
  #define DS1511_WDE	0x02
  #define DS1511_WDS	0x01
  #define DS1511_RAM_MAX	0xff
  
  #define RTC_CMD		DS1511_CONTROL_B
  #define RTC_CMD1	DS1511_CONTROL_A
  
  #define RTC_ALARM_SEC	DS1511_AM1_SEC
  #define RTC_ALARM_MIN	DS1511_AM2_MIN
  #define RTC_ALARM_HOUR	DS1511_AM3_HOUR
  #define RTC_ALARM_DATE	DS1511_AM4_DATE
  
  #define RTC_SEC		DS1511_SEC
  #define RTC_MIN		DS1511_MIN
  #define RTC_HOUR	DS1511_HOUR
  #define RTC_DOW		DS1511_DOW
  #define RTC_DOM		DS1511_DOM
  #define RTC_MON		DS1511_MONTH
  #define RTC_YEAR	DS1511_YEAR
  #define RTC_CENTURY	DS1511_CENTURY
  
  #define RTC_TIE	DS1511_TIE
  #define RTC_TE	DS1511_TE
  
  struct rtc_plat_data {
  	struct rtc_device *rtc;
  	void __iomem *ioaddr;		/* virtual base address */

  	int size;				/* amount of memory mapped */
  	int irq;
  	unsigned int irqen;
  	int alrm_sec;
  	int alrm_min;
  	int alrm_hour;
  	int alrm_mday;

  	spinlock_t lock;

  };
  
  static DEFINE_SPINLOCK(ds1511_lock);
  
  static __iomem char *ds1511_base;
  static u32 reg_spacing = 1;
  
   static noinline void
  rtc_write(uint8_t val, uint32_t reg)
  {
  	writeb(val, ds1511_base + (reg * reg_spacing));
  }
  
   static inline void
  rtc_write_alarm(uint8_t val, enum ds1511reg reg)
  {
  	rtc_write((val | 0x80), reg);
  }
  
   static noinline uint8_t
  rtc_read(enum ds1511reg reg)
  {
  	return readb(ds1511_base + (reg * reg_spacing));
  }
  
   static inline void
  rtc_disable_update(void)
  {
  	rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
  }
  
   static void
  rtc_enable_update(void)
  {
  	rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
  }
  
  /*
   * #define DS1511_WDOG_RESET_SUPPORT
   *
   * Uncomment this if you want to use these routines in
   * some platform code.
   */
  #ifdef DS1511_WDOG_RESET_SUPPORT
  /*
   * just enough code to set the watchdog timer so that it
   * will reboot the system
   */
   void
  ds1511_wdog_set(unsigned long deciseconds)
  {
  	/*
  	 * the wdog timer can take 99.99 seconds
  	 */
  	deciseconds %= 10000;
  	/*
  	 * set the wdog values in the wdog registers
  	 */

  	rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
  	rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);

  	/*
  	 * set wdog enable and wdog 'steering' bit to issue a reset
  	 */
  	rtc_write(DS1511_WDE | DS1511_WDS, RTC_CMD);
  }
  
   void
  ds1511_wdog_disable(void)
  {
  	/*
  	 * clear wdog enable and wdog 'steering' bits
  	 */
  	rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
  	/*
  	 * clear the wdog counter
  	 */
  	rtc_write(0, DS1511_WD_MSEC);
  	rtc_write(0, DS1511_WD_SEC);
  }
  #endif
  
  /*
   * set the rtc chip's idea of the time.
   * stupidly, some callers call with year unmolested;
   * and some call with  year = year - 1900.  thanks.
   */

  static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)

  {
  	u8 mon, day, dow, hrs, min, sec, yrs, cen;

  	unsigned long flags;

  
  	/*
  	 * won't have to change this for a while
  	 */
  	if (rtc_tm->tm_year < 1900) {
  		rtc_tm->tm_year += 1900;
  	}
  
  	if (rtc_tm->tm_year < 1970) {
  		return -EINVAL;
  	}
  	yrs = rtc_tm->tm_year % 100;
  	cen = rtc_tm->tm_year / 100;
  	mon = rtc_tm->tm_mon + 1;   /* tm_mon starts at zero */
  	day = rtc_tm->tm_mday;
  	dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
  	hrs = rtc_tm->tm_hour;
  	min = rtc_tm->tm_min;
  	sec = rtc_tm->tm_sec;
  
  	if ((mon > 12) || (day == 0)) {
  		return -EINVAL;
  	}
  
  	if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year)) {
  		return -EINVAL;
  	}
  
  	if ((hrs >= 24) || (min >= 60) || (sec >= 60)) {
  		return -EINVAL;
  	}
  
  	/*
  	 * each register is a different number of valid bits
  	 */

  	sec = bin2bcd(sec) & 0x7f;
  	min = bin2bcd(min) & 0x7f;
  	hrs = bin2bcd(hrs) & 0x3f;
  	day = bin2bcd(day) & 0x3f;
  	mon = bin2bcd(mon) & 0x1f;
  	yrs = bin2bcd(yrs) & 0xff;
  	cen = bin2bcd(cen) & 0xff;

  
  	spin_lock_irqsave(&ds1511_lock, flags);
  	rtc_disable_update();
  	rtc_write(cen, RTC_CENTURY);
  	rtc_write(yrs, RTC_YEAR);
  	rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
  	rtc_write(day, RTC_DOM);
  	rtc_write(hrs, RTC_HOUR);
  	rtc_write(min, RTC_MIN);
  	rtc_write(sec, RTC_SEC);
  	rtc_write(dow, RTC_DOW);
  	rtc_enable_update();
  	spin_unlock_irqrestore(&ds1511_lock, flags);
  
  	return 0;
  }

  static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)

  {
  	unsigned int century;

  	unsigned long flags;

  
  	spin_lock_irqsave(&ds1511_lock, flags);
  	rtc_disable_update();
  
  	rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
  	rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
  	rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
  	rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
  	rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
  	rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
  	rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
  	century = rtc_read(RTC_CENTURY);
  
  	rtc_enable_update();
  	spin_unlock_irqrestore(&ds1511_lock, flags);

  	rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
  	rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
  	rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
  	rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
  	rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
  	rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
  	rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
  	century = bcd2bin(century) * 100;

  
  	/*
  	 * Account for differences between how the RTC uses the values
  	 * and how they are defined in a struct rtc_time;
  	 */
  	century += rtc_tm->tm_year;
  	rtc_tm->tm_year = century - 1900;
  
  	rtc_tm->tm_mon--;
  
  	if (rtc_valid_tm(rtc_tm) < 0) {
  		dev_err(dev, "retrieved date/time is not valid.
  ");
  		rtc_time_to_tm(0, rtc_tm);
  	}
  	return 0;
  }
  
  /*
   * write the alarm register settings
   *
   * we only have the use to interrupt every second, otherwise
   * known as the update interrupt, or the interrupt if the whole
   * date/hours/mins/secs matches.  the ds1511 has many more
   * permutations, but the kernel doesn't.
   */
   static void
  ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
  {
  	unsigned long flags;

  	spin_lock_irqsave(&pdata->lock, flags);

  	rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?

  	       0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,

  	       RTC_ALARM_DATE);
  	rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?

  	       0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,

  	       RTC_ALARM_HOUR);
  	rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?

  	       0x80 : bin2bcd(pdata->alrm_min) & 0x7f,

  	       RTC_ALARM_MIN);
  	rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?

  	       0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,

  	       RTC_ALARM_SEC);
  	rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
  	rtc_read(RTC_CMD1);	/* clear interrupts */

  	spin_unlock_irqrestore(&pdata->lock, flags);

  }
  
   static int
  ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	if (pdata->irq <= 0)

  		return -EINVAL;

  	pdata->alrm_mday = alrm->time.tm_mday;
  	pdata->alrm_hour = alrm->time.tm_hour;
  	pdata->alrm_min = alrm->time.tm_min;
  	pdata->alrm_sec = alrm->time.tm_sec;
  	if (alrm->enabled) {
  		pdata->irqen |= RTC_AF;
  	}
  	ds1511_rtc_update_alarm(pdata);
  	return 0;
  }
  
   static int
  ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	if (pdata->irq <= 0)

  		return -EINVAL;

  	alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
  	alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
  	alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
  	alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
  	alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
  	return 0;
  }
  
   static irqreturn_t
  ds1511_interrupt(int irq, void *dev_id)
  {
  	struct platform_device *pdev = dev_id;
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	unsigned long events = 0;

  	spin_lock(&pdata->lock);

  	/*
  	 * read and clear interrupt
  	 */

  	if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
  		events = RTC_IRQF;
  		if (rtc_read(RTC_ALARM_SEC) & 0x80)
  			events |= RTC_UF;
  		else
  			events |= RTC_AF;
  		if (likely(pdata->rtc))
  			rtc_update_irq(pdata->rtc, 1, events);
  	}
  	spin_unlock(&pdata->lock);
  	return events ? IRQ_HANDLED : IRQ_NONE;

  }

  static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)

  {
  	struct platform_device *pdev = to_platform_device(dev);
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);

  	if (pdata->irq <= 0)
  		return -EINVAL;
  	if (enabled)

  		pdata->irqen |= RTC_AF;

  	else
  		pdata->irqen &= ~RTC_AF;
  	ds1511_rtc_update_alarm(pdata);
  	return 0;
  }

  static const struct rtc_class_ops ds1511_rtc_ops = {

  	.read_time		= ds1511_rtc_read_time,
  	.set_time		= ds1511_rtc_set_time,
  	.read_alarm		= ds1511_rtc_read_alarm,
  	.set_alarm		= ds1511_rtc_set_alarm,
  	.alarm_irq_enable	= ds1511_rtc_alarm_irq_enable,

  };
  
   static ssize_t

  ds1511_nvram_read(struct file *filp, struct kobject *kobj,
  		  struct bin_attribute *ba,
  		  char *buf, loff_t pos, size_t size)

  {
  	ssize_t count;
  
  	/*
  	 * if count is more than one, turn on "burst" mode
  	 * turn it off when you're done
  	 */
  	if (size > 1) {
  		rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
  	}
  	if (pos > DS1511_RAM_MAX) {
  		pos = DS1511_RAM_MAX;
  	}
  	if (size + pos > DS1511_RAM_MAX + 1) {
  		size = DS1511_RAM_MAX - pos + 1;
  	}
  	rtc_write(pos, DS1511_RAMADDR_LSB);
  	for (count = 0; size > 0; count++, size--) {
  		*buf++ = rtc_read(DS1511_RAMDATA);
  	}
  	if (count > 1) {
  		rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
  	}
  	return count;
  }
  
   static ssize_t

  ds1511_nvram_write(struct file *filp, struct kobject *kobj,
  		   struct bin_attribute *bin_attr,
  		   char *buf, loff_t pos, size_t size)

  {
  	ssize_t count;
  
  	/*
  	 * if count is more than one, turn on "burst" mode
  	 * turn it off when you're done
  	 */
  	if (size > 1) {
  		rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
  	}
  	if (pos > DS1511_RAM_MAX) {
  		pos = DS1511_RAM_MAX;
  	}
  	if (size + pos > DS1511_RAM_MAX + 1) {
  		size = DS1511_RAM_MAX - pos + 1;
  	}
  	rtc_write(pos, DS1511_RAMADDR_LSB);
  	for (count = 0; size > 0; count++, size--) {
  		rtc_write(*buf++, DS1511_RAMDATA);
  	}
  	if (count > 1) {
  		rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
  	}
  	return count;
  }
  
  static struct bin_attribute ds1511_nvram_attr = {
  	.attr = {
  		.name = "nvram",

  		.mode = S_IRUGO | S_IWUSR,

  	},
  	.size = DS1511_RAM_MAX,
  	.read = ds1511_nvram_read,
  	.write = ds1511_nvram_write,
  };
  
   static int __devinit
  ds1511_rtc_probe(struct platform_device *pdev)
  {
  	struct rtc_device *rtc;
  	struct resource *res;

  	struct rtc_plat_data *pdata;

  	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;
  	ds1511_base = devm_ioremap(&pdev->dev, res->start, pdata->size);
  	if (!ds1511_base)
  		return -ENOMEM;

  	pdata->ioaddr = ds1511_base;
  	pdata->irq = platform_get_irq(pdev, 0);
  
  	/*
  	 * turn on the clock and the crystal, etc.
  	 */
  	rtc_write(0, RTC_CMD);
  	rtc_write(0, RTC_CMD1);
  	/*
  	 * clear the wdog counter
  	 */
  	rtc_write(0, DS1511_WD_MSEC);
  	rtc_write(0, DS1511_WD_SEC);
  	/*
  	 * start the clock
  	 */
  	rtc_enable_update();
  
  	/*
  	 * check for a dying bat-tree
  	 */
  	if (rtc_read(RTC_CMD1) & DS1511_BLF1) {
  		dev_warn(&pdev->dev, "voltage-low detected.
  ");
  	}

  	spin_lock_init(&pdata->lock);
  	platform_set_drvdata(pdev, pdata);

  	/*
  	 * if the platform has an interrupt in mind for this device,
  	 * then by all means, set it
  	 */

  	if (pdata->irq > 0) {

  		rtc_read(RTC_CMD1);

  		if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,

  			IRQF_DISABLED | IRQF_SHARED, pdev->name, pdev) < 0) {
  
  			dev_warn(&pdev->dev, "interrupt not available.
  ");

  			pdata->irq = 0;

  		}
  	}
  
  	rtc = rtc_device_register(pdev->name, &pdev->dev, &ds1511_rtc_ops,
  		THIS_MODULE);

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

  	pdata->rtc = rtc;

  	ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);

  	if (ret)

  		rtc_device_unregister(pdata->rtc);

  	return ret;
  }
  
   static int __devexit
  ds1511_rtc_remove(struct platform_device *pdev)
  {
  	struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
  
  	sysfs_remove_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
  	rtc_device_unregister(pdata->rtc);

  	if (pdata->irq > 0) {

  		/*
  		 * disable the alarm interrupt
  		 */
  		rtc_write(rtc_read(RTC_CMD) & ~RTC_TIE, RTC_CMD);
  		rtc_read(RTC_CMD1);

  	}

  	return 0;
  }

  /* work with hotplug and coldplug */
  MODULE_ALIAS("platform:ds1511");

  static struct platform_driver ds1511_rtc_driver = {
  	.probe		= ds1511_rtc_probe,
  	.remove		= __devexit_p(ds1511_rtc_remove),
  	.driver		= {
  		.name	= "ds1511",
  		.owner	= THIS_MODULE,
  	},
  };

  module_platform_driver(ds1511_rtc_driver);

  MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");

  MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_VERSION);