/*
   * Watchdog driver for Atmel AT91RM9200 (Thunder)
   *
   *  Copyright (C) 2003 SAN People (Pty) Ltd
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */

  #include <linux/bitops.h>

  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/init.h>

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

  #include <mach/at91_st.h>

  #define WDT_DEFAULT_TIME	5	/* seconds */
  #define WDT_MAX_TIME		256	/* seconds */

  
  static int wdt_time = WDT_DEFAULT_TIME;
  static int 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, int, 0);

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

  #endif

  
  
  static unsigned long at91wdt_busy;
  
  /* ......................................................................... */
  
  /*
   * Disable the watchdog.
   */

  static inline void at91_wdt_stop(void)

  {
  	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  }
  
  /*
   * Enable and reset the watchdog.
   */

  static inline void at91_wdt_start(void)

  {

  	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  				(((65536 * wdt_time) >> 8) & AT91_ST_WDV));

  	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  }
  
  /*
   * Reload the watchdog timer.  (ie, pat the watchdog)
   */

  static inline void at91_wdt_reload(void)

  {
  	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  }
  
  /* ......................................................................... */
  
  /*
   * Watchdog device is opened, and watchdog starts running.
   */
  static int at91_wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &at91wdt_busy))
  		return -EBUSY;
  
  	at91_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 at91_wdt_close(struct inode *inode, struct file *file)
  {

  	/* Disable the watchdog when file is closed */

  	if (!nowayout)

  		at91_wdt_stop();

  
  	clear_bit(0, &at91wdt_busy);
  	return 0;
  }
  
  /*
   * Change the watchdog time interval.
   */
  static int at91_wdt_settimeout(int new_time)
  {
  	/*

  	 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz

  	 *
  	 * Since WDV is a 16-bit counter, the maximum period is

  	 * 65536 / 256 = 256 seconds.

  	 */
  	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
  		return -EINVAL;

  	/* Set new watchdog time. It will be used when
  	   at91_wdt_start() is called. */

  	wdt_time = new_time;
  	return 0;
  }

  static const struct watchdog_info at91_wdt_info = {

  	.identity	= "at91 watchdog",
  	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  };
  
  /*
   * Handle commands from user-space.
   */

  static long at91_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, &at91_wdt_info,
  				sizeof(at91_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)
  			at91_wdt_stop();
  		if (new_value & WDIOS_ENABLECARD)

  			at91_wdt_start();

  		return 0;

  	case WDIOC_KEEPALIVE:
  		at91_wdt_reload();	/* pat the watchdog */
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_value, p))
  			return -EFAULT;
  		if (at91_wdt_settimeout(new_value))
  			return -EINVAL;
  		/* Enable new time value */
  		at91_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 at91_wdt_write(struct file *file, const char *data,
  						size_t len, loff_t *ppos)

  {
  	at91_wdt_reload();		/* pat the watchdog */
  	return len;
  }
  
  /* ......................................................................... */

  static const struct file_operations at91wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,

  	.unlocked_ioctl	= at91_wdt_ioctl,

  	.open		= at91_wdt_open,
  	.release	= at91_wdt_close,
  	.write		= at91_wdt_write,
  };
  
  static struct miscdevice at91wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &at91wdt_fops,
  };

  static int __devinit at91wdt_probe(struct platform_device *pdev)

  {
  	int res;

  	if (at91wdt_miscdev.parent)

  		return -EBUSY;

  	at91wdt_miscdev.parent = &pdev->dev;

  
  	res = misc_register(&at91wdt_miscdev);
  	if (res)
  		return res;

  	printk(KERN_INFO "AT91 Watchdog Timer enabled (%d seconds%s)
  ",
  				wdt_time, nowayout ? ", nowayout" : "");

  	return 0;
  }

  static int __devexit at91wdt_remove(struct platform_device *pdev)

  {
  	int res;
  
  	res = misc_deregister(&at91wdt_miscdev);
  	if (!res)

  		at91wdt_miscdev.parent = NULL;

  
  	return res;
  }
  
  static void at91wdt_shutdown(struct platform_device *pdev)
  {
  	at91_wdt_stop();
  }
  
  #ifdef CONFIG_PM
  
  static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
  {
  	at91_wdt_stop();
  	return 0;
  }
  
  static int at91wdt_resume(struct platform_device *pdev)
  {
  	if (at91wdt_busy)
  		at91_wdt_start();

  	return 0;

  }
  
  #else
  #define at91wdt_suspend NULL
  #define at91wdt_resume	NULL
  #endif
  
  static struct platform_driver at91wdt_driver = {
  	.probe		= at91wdt_probe,

  	.remove		= __devexit_p(at91wdt_remove),

  	.shutdown	= at91wdt_shutdown,
  	.suspend	= at91wdt_suspend,
  	.resume		= at91wdt_resume,
  	.driver		= {
  		.name	= "at91_wdt",
  		.owner	= THIS_MODULE,
  	},
  };
  
  static int __init at91_wdt_init(void)
  {

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

  	if (at91_wdt_settimeout(wdt_time)) {
  		at91_wdt_settimeout(WDT_DEFAULT_TIME);

  		pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256"
  						", using %d
  ", wdt_time);

  	}
  
  	return platform_driver_register(&at91wdt_driver);
  }

  static void __exit at91_wdt_exit(void)
  {

  	platform_driver_unregister(&at91wdt_driver);

  }
  
  module_init(at91_wdt_init);
  module_exit(at91_wdt_exit);
  
  MODULE_AUTHOR("Andrew Victor");
  MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

  MODULE_ALIAS("platform:at91_wdt");