/*
   * Watchdog driver for Kendin/Micrel KS8695.
   *
   * (C) 2007 Andrew Victor
   *
   * 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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/bitops.h>

  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/miscdevice.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/platform_device.h>
  #include <linux/types.h>
  #include <linux/watchdog.h>

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

  #include <mach/hardware.h>

  
  #define KS8695_TMR_OFFSET	(0xF0000 + 0xE400)
  #define KS8695_TMR_VA		(KS8695_IO_VA + KS8695_TMR_OFFSET)
  
  /*
   * Timer registers
   */
  #define KS8695_TMCON		(0x00)		/* Timer Control Register */
  #define KS8695_T0TC		(0x08)		/* Timer 0 Timeout Count Register */
  #define TMCON_T0EN		(1 << 0)	/* Timer 0 Enable */
  
  /* Timer0 Timeout Counter Register */
  #define T0TC_WATCHDOG		(0xff)		/* Enable watchdog mode */

  #define WDT_DEFAULT_TIME	5	/* seconds */
  #define WDT_MAX_TIME		171	/* seconds */
  
  static int wdt_time = WDT_DEFAULT_TIME;

  static bool nowayout = WATCHDOG_NOWAYOUT;

  
  module_param(wdt_time, int, 0);

  MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  					__MODULE_STRING(WDT_DEFAULT_TIME) ")");

  
  #ifdef CONFIG_WATCHDOG_NOWAYOUT

  module_param(nowayout, bool, 0);

  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

  #endif
  
  
  static unsigned long ks8695wdt_busy;

  static DEFINE_SPINLOCK(ks8695_lock);

  
  /* ......................................................................... */
  
  /*
   * Disable the watchdog.
   */

  static inline void ks8695_wdt_stop(void)

  {
  	unsigned long tmcon;

  	spin_lock(&ks8695_lock);

  	/* disable timer0 */
  	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

  	spin_unlock(&ks8695_lock);

  }
  
  /*
   * Enable and reset the watchdog.
   */

  static inline void ks8695_wdt_start(void)

  {
  	unsigned long tmcon;

  	unsigned long tval = wdt_time * KS8695_CLOCK_RATE;

  	spin_lock(&ks8695_lock);

  	/* disable timer0 */
  	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
  
  	/* program timer0 */
  	__raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
  
  	/* re-enable timer0 */
  	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

  	spin_unlock(&ks8695_lock);

  }
  
  /*
   * Reload the watchdog timer.  (ie, pat the watchdog)
   */

  static inline void ks8695_wdt_reload(void)

  {
  	unsigned long tmcon;

  	spin_lock(&ks8695_lock);

  	/* disable, then re-enable timer0 */
  	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
  	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
  	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);

  	spin_unlock(&ks8695_lock);

  }
  
  /*
   * Change the watchdog time interval.
   */
  static int ks8695_wdt_settimeout(int new_time)
  {
  	/*

  	 * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz

  	 *
  	 * Since WDV is a 16-bit counter, the maximum period is
  	 * 65536 / 0.256 = 256 seconds.
  	 */
  	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
  		return -EINVAL;

  	/* Set new watchdog time. It will be used when
  	   ks8695_wdt_start() is called. */

  	wdt_time = new_time;
  	return 0;
  }
  
  /* ......................................................................... */
  
  /*
   * Watchdog device is opened, and watchdog starts running.
   */
  static int ks8695_wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &ks8695wdt_busy))
  		return -EBUSY;
  
  	ks8695_wdt_start();
  	return nonseekable_open(inode, file);
  }
  
  /*
   * Close the watchdog device.
   * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
   *  disabled.
   */
  static int ks8695_wdt_close(struct inode *inode, struct file *file)
  {

  	/* Disable the watchdog when file is closed */

  	if (!nowayout)

  		ks8695_wdt_stop();

  	clear_bit(0, &ks8695wdt_busy);
  	return 0;
  }

  static const struct watchdog_info ks8695_wdt_info = {

  	.identity	= "ks8695 watchdog",
  	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  };
  
  /*
   * Handle commands from user-space.
   */

  static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;
  	int new_value;

  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &ks8695_wdt_info,
  					sizeof(ks8695_wdt_info)) ? -EFAULT : 0;

  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  	case WDIOC_SETOPTIONS:
  		if (get_user(new_value, p))
  			return -EFAULT;
  		if (new_value & WDIOS_DISABLECARD)
  			ks8695_wdt_stop();
  		if (new_value & WDIOS_ENABLECARD)

  			ks8695_wdt_start();

  		return 0;

  	case WDIOC_KEEPALIVE:
  		ks8695_wdt_reload();	/* pat the watchdog */
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_value, p))
  			return -EFAULT;
  		if (ks8695_wdt_settimeout(new_value))
  			return -EINVAL;
  		/* Enable new time value */
  		ks8695_wdt_start();
  		/* Return current value */
  		return put_user(wdt_time, p);
  	case WDIOC_GETTIMEOUT:
  		return put_user(wdt_time, p);

  	default:
  		return -ENOTTY;

  	}
  }
  
  /*
   * Pat the watchdog whenever device is written to.
   */

  static ssize_t ks8695_wdt_write(struct file *file, const char *data,
  						size_t len, loff_t *ppos)

  {
  	ks8695_wdt_reload();		/* pat the watchdog */
  	return len;
  }
  
  /* ......................................................................... */
  
  static const struct file_operations ks8695wdt_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,

  	.unlocked_ioctl	= ks8695_wdt_ioctl,

  	.open		= ks8695_wdt_open,
  	.release	= ks8695_wdt_close,
  	.write		= ks8695_wdt_write,
  };
  
  static struct miscdevice ks8695wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &ks8695wdt_fops,
  };

  static int ks8695wdt_probe(struct platform_device *pdev)

  {
  	int res;
  
  	if (ks8695wdt_miscdev.parent)
  		return -EBUSY;
  	ks8695wdt_miscdev.parent = &pdev->dev;
  
  	res = misc_register(&ks8695wdt_miscdev);
  	if (res)
  		return res;

  	pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)
  ",
  		wdt_time, nowayout ? ", nowayout" : "");

  	return 0;
  }

  static int ks8695wdt_remove(struct platform_device *pdev)

  {

  	misc_deregister(&ks8695wdt_miscdev);
  	ks8695wdt_miscdev.parent = NULL;

  	return 0;

  }
  
  static void ks8695wdt_shutdown(struct platform_device *pdev)
  {
  	ks8695_wdt_stop();
  }
  
  #ifdef CONFIG_PM
  
  static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
  {
  	ks8695_wdt_stop();
  	return 0;
  }
  
  static int ks8695wdt_resume(struct platform_device *pdev)
  {
  	if (ks8695wdt_busy)
  		ks8695_wdt_start();
  	return 0;
  }
  
  #else
  #define ks8695wdt_suspend NULL
  #define ks8695wdt_resume	NULL
  #endif
  
  static struct platform_driver ks8695wdt_driver = {
  	.probe		= ks8695wdt_probe,

  	.remove		= ks8695wdt_remove,

  	.shutdown	= ks8695wdt_shutdown,
  	.suspend	= ks8695wdt_suspend,
  	.resume		= ks8695wdt_resume,
  	.driver		= {
  		.name	= "ks8695_wdt",

  	},
  };
  
  static int __init ks8695_wdt_init(void)
  {

  	/* Check that the heartbeat value is within range;
  	   if not reset to the default */

  	if (ks8695_wdt_settimeout(wdt_time)) {
  		ks8695_wdt_settimeout(WDT_DEFAULT_TIME);

  		pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
  					", using %d
  ", wdt_time, WDT_MAX_TIME);

  	}

  	return platform_driver_register(&ks8695wdt_driver);
  }
  
  static void __exit ks8695_wdt_exit(void)
  {
  	platform_driver_unregister(&ks8695wdt_driver);
  }
  
  module_init(ks8695_wdt_init);
  module_exit(ks8695_wdt_exit);
  
  MODULE_AUTHOR("Andrew Victor");
  MODULE_DESCRIPTION("Watchdog driver for KS8695");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:ks8695_wdt");