/*

   * drivers/char/watchdog/ixp4xx_wdt.c

   *
   * Watchdog driver for Intel IXP4xx network processors
   *
   * Author: Deepak Saxena <dsaxena@plexity.net>
   *
   * Copyright 2004 (c) MontaVista, Software, Inc.
   * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
   *
   * This file is licensed under  the terms of the GNU General Public
   * License version 2. This program is licensed "as is" without any
   * warranty of any kind, whether express or implied.
   */

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

  #include <linux/uaccess.h>

  #include <mach/hardware.h>

  static int nowayout = WATCHDOG_NOWAYOUT;

  static int heartbeat = 60;	/* (secs) Default is 1 minute */
  static unsigned long wdt_status;
  static unsigned long boot_status;

  static DEFINE_SPINLOCK(wdt_lock);

  
  #define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)
  
  #define	WDT_IN_USE		0
  #define	WDT_OK_TO_CLOSE		1

  static void wdt_enable(void)

  {

  	spin_lock(&wdt_lock);

  	*IXP4XX_OSWK = IXP4XX_WDT_KEY;
  	*IXP4XX_OSWE = 0;
  	*IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
  	*IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
  	*IXP4XX_OSWK = 0;

  	spin_unlock(&wdt_lock);

  }

  static void wdt_disable(void)

  {

  	spin_lock(&wdt_lock);

  	*IXP4XX_OSWK = IXP4XX_WDT_KEY;
  	*IXP4XX_OSWE = 0;
  	*IXP4XX_OSWK = 0;

  	spin_unlock(&wdt_lock);

  }

  static int ixp4xx_wdt_open(struct inode *inode, struct file *file)

  {
  	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  		return -EBUSY;
  
  	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

  	wdt_enable();

  	return nonseekable_open(inode, file);
  }
  
  static ssize_t
  ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
  {
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  			for (i = 0; i != len; i++) {
  				char c;
  
  				if (get_user(c, data + i))
  					return -EFAULT;
  				if (c == 'V')
  					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
  			}
  		}
  		wdt_enable();
  	}

  	return len;
  }

  static const struct watchdog_info ident = {

  	.options	= WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
  			  WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
  	.identity	= "IXP4xx Watchdog",
  };

  static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {

  	int ret = -ENOTTY;

  	int time;
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		ret = copy_to_user((struct watchdog_info *)arg, &ident,
  				   sizeof(ident)) ? -EFAULT : 0;
  		break;
  
  	case WDIOC_GETSTATUS:
  		ret = put_user(0, (int *)arg);
  		break;
  
  	case WDIOC_GETBOOTSTATUS:
  		ret = put_user(boot_status, (int *)arg);
  		break;

  	case WDIOC_KEEPALIVE:
  		wdt_enable();
  		ret = 0;
  		break;

  	case WDIOC_SETTIMEOUT:
  		ret = get_user(time, (int *)arg);
  		if (ret)
  			break;
  
  		if (time <= 0 || time > 60) {
  			ret = -EINVAL;
  			break;
  		}
  
  		heartbeat = time;
  		wdt_enable();
  		/* Fall through */
  
  	case WDIOC_GETTIMEOUT:
  		ret = put_user(heartbeat, (int *)arg);
  		break;

  	}
  	return ret;
  }

  static int ixp4xx_wdt_release(struct inode *inode, struct file *file)

  {

  	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))

  		wdt_disable();

  	else

  		printk(KERN_CRIT "WATCHDOG: Device closed unexpectedly - "

  					"timer will not stop
  ");

  	clear_bit(WDT_IN_USE, &wdt_status);
  	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  
  	return 0;
  }

  static const struct file_operations ixp4xx_wdt_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= ixp4xx_wdt_write,

  	.unlocked_ioctl	= ixp4xx_wdt_ioctl,

  	.open		= ixp4xx_wdt_open,
  	.release	= ixp4xx_wdt_release,
  };

  static struct miscdevice ixp4xx_wdt_miscdev = {

  	.minor		= WATCHDOG_MINOR,

  	.name		= "watchdog",

  	.fops		= &ixp4xx_wdt_fops,
  };
  
  static int __init ixp4xx_wdt_init(void)
  {
  	int ret;

  	if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {

  		printk(KERN_ERR "IXP4XXX Watchdog: Rev. A0 IXP42x CPU detected"
  			" - watchdog disabled
  ");

  
  		return -ENODEV;
  	}

  	boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
  			WDIOF_CARDRESET : 0;

  	ret = misc_register(&ixp4xx_wdt_miscdev);
  	if (ret == 0)

  		printk(KERN_INFO "IXP4xx Watchdog Timer: heartbeat %d sec
  ",
  			heartbeat);

  	return ret;
  }
  
  static void __exit ixp4xx_wdt_exit(void)
  {
  	misc_deregister(&ixp4xx_wdt_miscdev);
  }
  
  
  module_init(ixp4xx_wdt_init);
  module_exit(ixp4xx_wdt_exit);
  
  MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
  MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");
  
  module_param(heartbeat, int, 0);
  MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");
  
  module_param(nowayout, int, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
  
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);