// SPDX-License-Identifier: GPL-2.0+

  /*
   *	Advantech Single Board Computer WDT driver
   *
   *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
   *
   *	Based on acquirewdt.c which is based on wdt.c.
   *	Original copyright messages:
   *

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

   *

   *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
   *	warranty for any of this software. This material is provided
   *	"AS-IS" and at no charge.
   *

   *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>

   *
   *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
   *	    Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
   *
   *	16-Oct-2002 Rob Radez <rob@osinvestor.com>
   *	    Clean up ioctls, clean up init + exit, add expect close support,
   *	    add wdt_start and wdt_stop as parameters.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/fs.h>
  #include <linux/ioport.h>

  #include <linux/platform_device.h>

  #include <linux/init.h>

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

  #define DRV_NAME "advantechwdt"

  #define WATCHDOG_NAME "Advantech WDT"

  #define WATCHDOG_TIMEOUT 60		/* 60 sec default timeout */

  /* the watchdog platform device */
  static struct platform_device *advwdt_platform_device;

  static unsigned long advwdt_is_open;
  static char adv_expect_close;
  
  /*
   *	You must set these - there is no sane way to probe for this board.
   *
   *	To enable or restart, write the timeout value in seconds (1 to 63)
   *	to I/O port wdt_start.  To disable, read I/O port wdt_stop.
   *	Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
   *	check your manual (at least the PCA-6159 seems to be different -
   *	the manual says wdt_stop is 0x43, not 0x443).
   *	(0x43 is also a write-only control register for the 8254 timer!)
   */
  
  static int wdt_stop = 0x443;
  module_param(wdt_stop, int, 0);
  MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");
  
  static int wdt_start = 0x443;
  module_param(wdt_start, int, 0);
  MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");
  
  static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
  module_param(timeout, int, 0);

  MODULE_PARM_DESC(timeout,
  	"Watchdog timeout in seconds. 1<= timeout <=63, default="
  		__MODULE_STRING(WATCHDOG_TIMEOUT) ".");

  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) ")");

  
  /*

   *	Watchdog Operations

   */

  static void advwdt_ping(void)

  {
  	/* Write a watchdog value */
  	outb_p(timeout, wdt_start);
  }

  static void advwdt_disable(void)

  {
  	inb_p(wdt_stop);
  }

  static int advwdt_set_heartbeat(int t)

  {

  	if (t < 1 || t > 63)

  		return -EINVAL;

  	timeout = t;
  	return 0;
  }

  /*
   *	/dev/watchdog handling
   */

  static ssize_t advwdt_write(struct file *file, const char __user *buf,
  						size_t count, loff_t *ppos)

  {
  	if (count) {
  		if (!nowayout) {
  			size_t i;
  
  			adv_expect_close = 0;
  
  			for (i = 0; i != count; i++) {
  				char c;

  				if (get_user(c, buf + i))

  					return -EFAULT;
  				if (c == 'V')
  					adv_expect_close = 42;
  			}
  		}
  		advwdt_ping();
  	}
  	return count;
  }

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

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

  	static const struct watchdog_info ident = {

  		.options = WDIOF_KEEPALIVEPING |
  			   WDIOF_SETTIMEOUT |
  			   WDIOF_MAGICCLOSE,

  		.firmware_version = 1,

  		.identity = WATCHDOG_NAME,

  	};
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:

  		if (copy_to_user(argp, &ident, sizeof(ident)))
  			return -EFAULT;
  		break;

  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:

  		return put_user(0, p);

  	case WDIOC_SETOPTIONS:
  	{

  		int options, retval = -EINVAL;

  		if (get_user(options, p))
  			return -EFAULT;
  		if (options & WDIOS_DISABLECARD) {
  			advwdt_disable();
  			retval = 0;
  		}
  		if (options & WDIOS_ENABLECARD) {
  			advwdt_ping();
  			retval = 0;
  		}
  		return retval;

  	}

  	case WDIOC_KEEPALIVE:
  		advwdt_ping();
  		break;
  
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		if (advwdt_set_heartbeat(new_timeout))
  			return -EINVAL;
  		advwdt_ping();

  		/* fall through */

  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);

  	default:

  		return -ENOTTY;

  	}
  	return 0;
  }

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

  {
  	if (test_and_set_bit(0, &advwdt_is_open))
  		return -EBUSY;
  	/*
  	 *	Activate
  	 */
  
  	advwdt_ping();

  	return stream_open(inode, file);

  }

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

  {
  	if (adv_expect_close == 42) {
  		advwdt_disable();
  	} else {

  		pr_crit("Unexpected close, not stopping watchdog!
  ");

  		advwdt_ping();
  	}
  	clear_bit(0, &advwdt_is_open);
  	adv_expect_close = 0;
  	return 0;
  }
  
  /*

   *	Kernel Interfaces
   */

  static const struct file_operations advwdt_fops = {

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

  	.unlocked_ioctl	= advwdt_ioctl,

  	.open		= advwdt_open,
  	.release	= advwdt_close,
  };
  
  static struct miscdevice advwdt_miscdev = {

  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &advwdt_fops,

  };
  
  /*

   *	Init & exit routines
   */

  static int __init advwdt_probe(struct platform_device *dev)

  {
  	int ret;

  	if (wdt_stop != wdt_start) {
  		if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {

  			pr_err("I/O address 0x%04x already in use
  ",
  			       wdt_stop);

  			ret = -EIO;
  			goto out;
  		}
  	}
  
  	if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {

  		pr_err("I/O address 0x%04x already in use
  ", wdt_start);

  		ret = -EIO;
  		goto unreg_stop;
  	}

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

  	if (advwdt_set_heartbeat(timeout)) {
  		advwdt_set_heartbeat(WATCHDOG_TIMEOUT);

  		pr_info("timeout value must be 1<=x<=63, using %d
  ", timeout);

  	}

  	ret = misc_register(&advwdt_miscdev);
  	if (ret != 0) {

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

  		goto unreg_regions;

  	}

  	pr_info("initialized. timeout=%d sec (nowayout=%d)
  ",

  		timeout, nowayout);

  out:
  	return ret;

  unreg_regions:
  	release_region(wdt_start, 1);
  unreg_stop:
  	if (wdt_stop != wdt_start)
  		release_region(wdt_stop, 1);
  	goto out;
  }

  static int advwdt_remove(struct platform_device *dev)

  {
  	misc_deregister(&advwdt_miscdev);

  	release_region(wdt_start, 1);
  	if (wdt_stop != wdt_start)
  		release_region(wdt_stop, 1);

  
  	return 0;
  }

  static void advwdt_shutdown(struct platform_device *dev)

  {
  	/* Turn the WDT off if we have a soft shutdown */
  	advwdt_disable();
  }

  static struct platform_driver advwdt_driver = {

  	.remove		= advwdt_remove,

  	.shutdown	= advwdt_shutdown,

  	.driver		= {

  		.name	= DRV_NAME,
  	},
  };

  static int __init advwdt_init(void)

  {
  	int err;

  	pr_info("WDT driver for Advantech single board computer initialising
  ");

  	advwdt_platform_device = platform_device_register_simple(DRV_NAME,
  								-1, NULL, 0);

  	if (IS_ERR(advwdt_platform_device))
  		return PTR_ERR(advwdt_platform_device);
  
  	err = platform_driver_probe(&advwdt_driver, advwdt_probe);
  	if (err)
  		goto unreg_platform_device;

  
  	return 0;

  unreg_platform_device:
  	platform_device_unregister(advwdt_platform_device);

  	return err;
  }

  static void __exit advwdt_exit(void)

  {
  	platform_device_unregister(advwdt_platform_device);
  	platform_driver_unregister(&advwdt_driver);

  	pr_info("Watchdog Module Unloaded
  ");

  }
  
  module_init(advwdt_init);
  module_exit(advwdt_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Marek Michalkiewicz <marekm@linux.org.pl>");
  MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");