/*
   *  PNX833x Hardware Watchdog Driver
   *  Copyright 2008 NXP Semiconductors
   *  Daniel Laird <daniel.j.laird@nxp.com>
   *  Andre McCurdy <andre.mccurdy@nxp.com>
   *
   *  Heavily based upon - IndyDog	0.3
   *  A Hardware Watchdog Device for SGI IP22
   *
   * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
   *
   * 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.
   *
   * based on softdog.c by Alan Cox <alan@redhat.com>
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>
  #include <linux/init.h>
  #include <asm/mach-pnx833x/pnx833x.h>

  #define WATCHDOG_TIMEOUT 30		/* 30 sec Maximum timeout */
  #define WATCHDOG_COUNT_FREQUENCY 68000000U /* Watchdog counts at 68MHZ. */

  #define	PNX_WATCHDOG_TIMEOUT	(WATCHDOG_TIMEOUT * WATCHDOG_COUNT_FREQUENCY)
  #define PNX_TIMEOUT_VALUE	2040000000U

  
  /** CONFIG block */
  #define PNX833X_CONFIG                      (0x07000U)
  #define PNX833X_CONFIG_CPU_WATCHDOG         (0x54)
  #define PNX833X_CONFIG_CPU_WATCHDOG_COMPARE (0x58)
  #define PNX833X_CONFIG_CPU_COUNTERS_CONTROL (0x1c)
  
  /** RESET block */
  #define PNX833X_RESET                       (0x08000U)
  #define PNX833X_RESET_CONFIG                (0x08)
  
  static int pnx833x_wdt_alive;
  
  /* Set default timeout in MHZ.*/

  static int pnx833x_wdt_timeout = PNX_WATCHDOG_TIMEOUT;

  module_param(pnx833x_wdt_timeout, int, 0);
  MODULE_PARM_DESC(timeout, "Watchdog timeout in Mhz. (68Mhz clock), default="

  			__MODULE_STRING(PNX_TIMEOUT_VALUE) "(30 seconds).");

  static bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);

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

  #define START_DEFAULT	1
  static int start_enabled = START_DEFAULT;

  module_param(start_enabled, int, 0);
  MODULE_PARM_DESC(start_enabled, "Watchdog is started on module insertion "

  				"(default=" __MODULE_STRING(START_DEFAULT) ")");

  
  static void pnx833x_wdt_start(void)
  {
  	/* Enable watchdog causing reset. */
  	PNX833X_REG(PNX833X_RESET + PNX833X_RESET_CONFIG) |= 0x1;
  	/* Set timeout.*/
  	PNX833X_REG(PNX833X_CONFIG +
  		PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  	/* Enable watchdog. */
  	PNX833X_REG(PNX833X_CONFIG +
  				PNX833X_CONFIG_CPU_COUNTERS_CONTROL) |= 0x1;

  	pr_info("Started watchdog timer
  ");

  }
  
  static void pnx833x_wdt_stop(void)
  {
  	/* Disable watchdog causing reset. */
  	PNX833X_REG(PNX833X_RESET + PNX833X_CONFIG) &= 0xFFFFFFFE;
  	/* Disable watchdog.*/
  	PNX833X_REG(PNX833X_CONFIG +
  			PNX833X_CONFIG_CPU_COUNTERS_CONTROL) &= 0xFFFFFFFE;

  	pr_info("Stopped watchdog timer
  ");

  }
  
  static void pnx833x_wdt_ping(void)
  {
  	PNX833X_REG(PNX833X_CONFIG +
  		PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = pnx833x_wdt_timeout;
  }
  
  /*
   *	Allow only one person to hold it open
   */
  static int pnx833x_wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &pnx833x_wdt_alive))
  		return -EBUSY;
  
  	if (nowayout)
  		__module_get(THIS_MODULE);
  
  	/* Activate timer */
  	if (!start_enabled)
  		pnx833x_wdt_start();
  
  	pnx833x_wdt_ping();

  	pr_info("Started watchdog timer
  ");

  
  	return nonseekable_open(inode, file);
  }
  
  static int pnx833x_wdt_release(struct inode *inode, struct file *file)
  {
  	/* Shut off the timer.
  	 * Lock it in if it's a module and we defined ...NOWAYOUT */
  	if (!nowayout)
  		pnx833x_wdt_stop(); /* Turn the WDT off */
  
  	clear_bit(0, &pnx833x_wdt_alive);
  	return 0;
  }
  
  static ssize_t pnx833x_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  {
  	/* Refresh the timer. */
  	if (len)
  		pnx833x_wdt_ping();
  
  	return len;
  }
  
  static long pnx833x_wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)
  {
  	int options, new_timeout = 0;
  	uint32_t timeout, timeout_left = 0;

  	static const struct watchdog_info ident = {

  		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
  		.firmware_version = 0,
  		.identity = "Hardware Watchdog for PNX833x",
  	};
  
  	switch (cmd) {
  	default:
  		return -ENOTTY;
  
  	case WDIOC_GETSUPPORT:
  		if (copy_to_user((struct watchdog_info *)arg,
  				 &ident, sizeof(ident)))
  			return -EFAULT;
  		return 0;
  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, (int *)arg);
  
  	case WDIOC_SETOPTIONS:
  		if (get_user(options, (int *)arg))
  			return -EFAULT;
  
  		if (options & WDIOS_DISABLECARD)
  			pnx833x_wdt_stop();
  
  		if (options & WDIOS_ENABLECARD)
  			pnx833x_wdt_start();
  
  		return 0;
  
  	case WDIOC_KEEPALIVE:
  		pnx833x_wdt_ping();
  		return 0;
  
  	case WDIOC_SETTIMEOUT:
  	{
  		if (get_user(new_timeout, (int *)arg))
  			return -EFAULT;
  
  		pnx833x_wdt_timeout = new_timeout;
  		PNX833X_REG(PNX833X_CONFIG +
  			PNX833X_CONFIG_CPU_WATCHDOG_COMPARE) = new_timeout;
  		return put_user(new_timeout, (int *)arg);
  	}
  
  	case WDIOC_GETTIMEOUT:
  		timeout = PNX833X_REG(PNX833X_CONFIG +
  					PNX833X_CONFIG_CPU_WATCHDOG_COMPARE);
  		return put_user(timeout, (int *)arg);
  
  	case WDIOC_GETTIMELEFT:
  		timeout_left = PNX833X_REG(PNX833X_CONFIG +
  						PNX833X_CONFIG_CPU_WATCHDOG);
  		return put_user(timeout_left, (int *)arg);
  
  	}
  }
  
  static int pnx833x_wdt_notify_sys(struct notifier_block *this,
  					unsigned long code, void *unused)
  {
  	if (code == SYS_DOWN || code == SYS_HALT)
  		pnx833x_wdt_stop(); /* Turn the WDT off */
  
  	return NOTIFY_DONE;
  }
  
  static const struct file_operations pnx833x_wdt_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= pnx833x_wdt_write,
  	.unlocked_ioctl	= pnx833x_wdt_ioctl,
  	.open		= pnx833x_wdt_open,
  	.release	= pnx833x_wdt_release,
  };
  
  static struct miscdevice pnx833x_wdt_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &pnx833x_wdt_fops,
  };
  
  static struct notifier_block pnx833x_wdt_notifier = {
  	.notifier_call = pnx833x_wdt_notify_sys,
  };

  static int __init watchdog_init(void)
  {
  	int ret, cause;
  
  	/* Lets check the reason for the reset.*/
  	cause = PNX833X_REG(PNX833X_RESET);
  	/*If bit 31 is set then watchdog was cause of reset.*/
  	if (cause & 0x80000000) {

  		pr_info("The system was previously reset due to the watchdog firing - please investigate...
  ");

  	}
  
  	ret = register_reboot_notifier(&pnx833x_wdt_notifier);
  	if (ret) {

  		pr_err("cannot register reboot notifier (err=%d)
  ", ret);

  		return ret;
  	}
  
  	ret = misc_register(&pnx833x_wdt_miscdev);
  	if (ret) {

  		pr_err("cannot register miscdev on minor=%d (err=%d)
  ",
  		       WATCHDOG_MINOR, ret);

  		unregister_reboot_notifier(&pnx833x_wdt_notifier);
  		return ret;
  	}

  	pr_info("Hardware Watchdog Timer for PNX833x: Version 0.1
  ");

  	if (start_enabled)
  		pnx833x_wdt_start();
  
  	return 0;
  }
  
  static void __exit watchdog_exit(void)
  {
  	misc_deregister(&pnx833x_wdt_miscdev);
  	unregister_reboot_notifier(&pnx833x_wdt_notifier);
  }
  
  module_init(watchdog_init);
  module_exit(watchdog_exit);
  
  MODULE_AUTHOR("Daniel Laird/Andre McCurdy");
  MODULE_DESCRIPTION("Hardware Watchdog Device for PNX833x");
  MODULE_LICENSE("GPL");