// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *	Intel 21285 watchdog driver
   *	Copyright (c) Phil Blundell <pb@nexus.co.uk>, 1998
   *
   *	based on
   *
   *	SoftDog	0.05:	A Software Watchdog Device
   *

   *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   *						All Rights Reserved.

   */

  #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/reboot.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>

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

  #include <mach/hardware.h>

  #include <asm/mach-types.h>

  #include <asm/system_info.h>

  #include <asm/hardware/dec21285.h>
  
  /*
   * Define this to stop the watchdog actually rebooting the machine.
   */
  #undef ONLY_TESTING
  
  static unsigned int soft_margin = 60;		/* in seconds */
  static unsigned int reload;
  static unsigned long timer_alive;
  
  #ifdef ONLY_TESTING
  /*
   *	If the timer expires..
   */

  static void watchdog_fire(int irq, void *dev_id)

  {

  	pr_crit("Would Reboot
  ");

  	*CSR_TIMER4_CNTL = 0;
  	*CSR_TIMER4_CLR = 0;
  }
  #endif
  
  /*
   *	Refresh the timer.
   */
  static void watchdog_ping(void)
  {
  	*CSR_TIMER4_LOAD = reload;
  }
  
  /*
   *	Allow only one person to hold it open
   */
  static int watchdog_open(struct inode *inode, struct file *file)
  {
  	int ret;
  
  	if (*CSR_SA110_CNTL & (1 << 13))
  		return -EBUSY;
  
  	if (test_and_set_bit(1, &timer_alive))
  		return -EBUSY;
  
  	reload = soft_margin * (mem_fclk_21285 / 256);
  
  	*CSR_TIMER4_CLR = 0;
  	watchdog_ping();
  	*CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
  		| TIMER_CNTL_DIV256;
  
  #ifdef ONLY_TESTING
  	ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
  	if (ret) {
  		*CSR_TIMER4_CNTL = 0;
  		clear_bit(1, &timer_alive);
  	}
  #else
  	/*
  	 * Setting this bit is irreversible; once enabled, there is
  	 * no way to disable the watchdog.
  	 */
  	*CSR_SA110_CNTL |= 1 << 13;
  
  	ret = 0;
  #endif

  	stream_open(inode, file);

  	return ret;
  }
  
  /*
   *	Shut off the timer.
   *	Note: if we really have enabled the watchdog, there
   *	is no way to turn off.
   */
  static int watchdog_release(struct inode *inode, struct file *file)
  {
  #ifdef ONLY_TESTING
  	free_irq(IRQ_TIMER4, NULL);
  	clear_bit(1, &timer_alive);
  #endif
  	return 0;
  }

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

  {
  	/*
  	 *	Refresh the timer.
  	 */
  	if (len)
  		watchdog_ping();
  
  	return len;
  }

  static const struct watchdog_info ident = {

  	.options	= WDIOF_SETTIMEOUT,
  	.identity	= "Footbridge Watchdog",
  };

  static long watchdog_ioctl(struct file *file, unsigned int cmd,

  			   unsigned long arg)

  {

  	int __user *int_arg = (int __user *)arg;

  	int new_margin, ret = -ENOTTY;

  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		ret = 0;

  		if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))

  			ret = -EFAULT;
  		break;
  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:

  		ret = put_user(0, int_arg);

  		break;
  
  	case WDIOC_KEEPALIVE:
  		watchdog_ping();
  		ret = 0;
  		break;
  
  	case WDIOC_SETTIMEOUT:

  		ret = get_user(new_margin, int_arg);

  		if (ret)
  			break;
  
  		/* Arbitrary, can't find the card's limits */
  		if (new_margin < 0 || new_margin > 60) {
  			ret = -EINVAL;
  			break;
  		}
  
  		soft_margin = new_margin;
  		reload = soft_margin * (mem_fclk_21285 / 256);
  		watchdog_ping();

  		fallthrough;

  	case WDIOC_GETTIMEOUT:

  		ret = put_user(soft_margin, int_arg);

  		break;
  	}
  	return ret;
  }

  static const struct file_operations watchdog_fops = {

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

  	.unlocked_ioctl	= watchdog_ioctl,

  	.compat_ioctl	= compat_ptr_ioctl,

  	.open		= watchdog_open,
  	.release	= watchdog_release,
  };
  
  static struct miscdevice watchdog_miscdev = {
  	.minor		= WATCHDOG_MINOR,
  	.name		= "watchdog",
  	.fops		= &watchdog_fops,
  };
  
  static int __init footbridge_watchdog_init(void)
  {
  	int retval;
  
  	if (machine_is_netwinder())
  		return -ENODEV;
  
  	retval = misc_register(&watchdog_miscdev);
  	if (retval < 0)
  		return retval;

  	pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec
  ",
  		soft_margin);

  
  	if (machine_is_cats())

  		pr_warn("Warning: Watchdog reset may not work on this machine
  ");

  	return 0;
  }
  
  static void __exit footbridge_watchdog_exit(void)
  {
  	misc_deregister(&watchdog_miscdev);
  }
  
  MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
  MODULE_DESCRIPTION("Footbridge watchdog driver");
  MODULE_LICENSE("GPL");

  
  module_param(soft_margin, int, 0);

  MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");

  
  module_init(footbridge_watchdog_init);
  module_exit(footbridge_watchdog_exit);