/*
   *	Watchdog driver for the SA11x0/PXA2xx
   *

   *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
   *	    Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>

   *
   *	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.
   *
   *	Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
   *	warranty for any of this software. This material is provided
   *	"AS-IS" and at no charge.
   *
   *	(c) Copyright 2000           Oleg Drokin <green@crimea.edu>
   *

   *	27/11/2000 Initial release

   */

  
  #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/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/init.h>

  #include <linux/io.h>

  #include <linux/bitops.h>

  #include <linux/uaccess.h>

  #include <linux/timex.h>

  
  #ifdef CONFIG_ARCH_PXA

  #include <mach/regs-ost.h>

  #endif

  #include <mach/reset.h>

  #include <mach/hardware.h>

  static unsigned long oscr_freq;

  static unsigned long sa1100wdt_users;

  static unsigned int pre_margin;

  static int boot_status;

  
  /*
   *	Allow only one person to hold it open
   */
  static int sa1100dog_open(struct inode *inode, struct file *file)
  {

  	if (test_and_set_bit(1, &sa1100wdt_users))

  		return -EBUSY;
  
  	/* Activate SA1100 Watchdog timer */

  	writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  	writel_relaxed(OSSR_M3, OSSR);
  	writel_relaxed(OWER_WME, OWER);
  	writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);

  	return nonseekable_open(inode, file);

  }
  
  /*

   * The watchdog cannot be disabled.
   *
   * Previous comments suggested that turning off the interrupt by
   * clearing OIER[E3] would prevent the watchdog timing out but this
   * does not appear to be true (at least on the PXA255).

   */
  static int sa1100dog_release(struct inode *inode, struct file *file)
  {

  	pr_crit("Device closed - timer will not stop
  ");

  	clear_bit(1, &sa1100wdt_users);

  	return 0;
  }

  static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  						size_t len, loff_t *ppos)

  {

  	if (len)

  		/* Refresh OSMR3 timer. */

  		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);

  	return len;
  }

  static const struct watchdog_info ident = {
  	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  				| WDIOF_KEEPALIVEPING,

  	.identity	= "SA1100/PXA255 Watchdog",

  	.firmware_version	= 1,

  };

  static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {

  	int ret = -ENOTTY;

  	int time;

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

  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:

  		ret = copy_to_user(argp, &ident,

  				   sizeof(ident)) ? -EFAULT : 0;
  		break;
  
  	case WDIOC_GETSTATUS:

  		ret = put_user(0, p);

  		break;
  
  	case WDIOC_GETBOOTSTATUS:

  		ret = put_user(boot_status, p);

  		break;

  	case WDIOC_KEEPALIVE:

  		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);

  		ret = 0;
  		break;

  	case WDIOC_SETTIMEOUT:

  		ret = get_user(time, p);

  		if (ret)
  			break;

  		if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {

  			ret = -EINVAL;
  			break;
  		}

  		pre_margin = oscr_freq * time;

  		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);

  		/*fall through*/
  
  	case WDIOC_GETTIMEOUT:

  		ret = put_user(pre_margin / oscr_freq, p);

  		break;

  	}
  	return ret;
  }

  static const struct file_operations sa1100dog_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= sa1100dog_write,

  	.unlocked_ioctl	= sa1100dog_ioctl,

  	.open		= sa1100dog_open,
  	.release	= sa1100dog_release,
  };

  static struct miscdevice sa1100dog_miscdev = {

  	.minor		= WATCHDOG_MINOR,

  	.name		= "watchdog",

  	.fops		= &sa1100dog_fops,
  };
  
  static int margin __initdata = 60;		/* (secs) Default is 1 minute */
  
  static int __init sa1100dog_init(void)
  {
  	int ret;

  	oscr_freq = get_clock_tick_rate();

  	/*
  	 * Read the reset status, and save it for later.  If
  	 * we suspend, RCSR will be cleared, and the watchdog
  	 * reset reason will be lost.
  	 */

  	boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
  				WDIOF_CARDRESET : 0;

  	pre_margin = oscr_freq * margin;

  
  	ret = misc_register(&sa1100dog_miscdev);
  	if (ret == 0)

  		pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec
  ",
  			margin);

  	return ret;
  }
  
  static void __exit sa1100dog_exit(void)
  {
  	misc_deregister(&sa1100dog_miscdev);
  }
  
  module_init(sa1100dog_init);
  module_exit(sa1100dog_exit);
  
  MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
  MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
  
  module_param(margin, int, 0);
  MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");

  MODULE_LICENSE("GPL");