drivers/watchdog/ib700wdt.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  *	IB700 Single Board Computer WDT driver
  *
  *	(c) Copyright 2001 Charles Howes <chowes@vsol.net>
  *
  *	Based on advantechwdt.c which is based on acquirewdt.c which
  *	is based on wdt.c.
  *
  *	(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
  *	     Added timeout module option to override default
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/miscdevice.h>
 #include <linux/watchdog.h>
 #include <linux/ioport.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/spinlock.h>
 #include <linux/moduleparam.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>


 static struct platform_device *ibwdt_platform_device;
 static unsigned long ibwdt_is_open;
 static DEFINE_SPINLOCK(ibwdt_lock);
 static char expect_close;

 /* Module information */
 #define DRV_NAME "ib700wdt"

 /*
  *
  * Watchdog Timer Configuration
  *
  * The function of the watchdog timer is to reset the system
  * automatically and is defined at I/O port 0443H.  To enable the
  * watchdog timer and allow the system to reset, write I/O port 0443H.
  * To disable the timer, write I/O port 0441H for the system to stop the
  * watchdog function.  The timer has a tolerance of 20% for its
  * intervals.
  *
  * The following describes how the timer should be programmed.
  *
  * Enabling Watchdog:
  * MOV AX,000FH (Choose the values from 0 to F)
  * MOV DX,0443H
  * OUT DX,AX
  *
  * Disabling Watchdog:
  * MOV AX,000FH (Any value is fine.)
  * MOV DX,0441H
  * OUT DX,AX
  *
  * Watchdog timer control table:
  * Level   Value  Time/sec | Level Value Time/sec
  *   1       F       0     |   9     7      16
  *   2       E       2     |   10    6      18
  *   3       D       4     |   11    5      20
  *   4       C       6     |   12    4      22
  *   5       B       8     |   13    3      24
  *   6       A       10    |   14    2      26
  *   7       9       12    |   15    1      28
  *   8       8       14    |   16    0      30
  *
  */

 #define WDT_STOP 0x441
 #define WDT_START 0x443

 /* Default timeout */
 #define WATCHDOG_TIMEOUT 30		/* 30 seconds +/- 20% */
 static int timeout = WATCHDOG_TIMEOUT;	/* in seconds */
 module_param(timeout, int, 0);
 MODULE_PARM_DESC(timeout,
 	"Watchdog timeout in seconds. 0<= timeout <=30, 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 ibwdt_ping(void)
 {
 	int wd_margin = 15 - ((timeout + 1) / 2);

 	spin_lock(&ibwdt_lock);

 	/* Write a watchdog value */
 	outb_p(wd_margin, WDT_START);

 	spin_unlock(&ibwdt_lock);
 }

 static void ibwdt_disable(void)
 {
 	spin_lock(&ibwdt_lock);
 	outb_p(0, WDT_STOP);
 	spin_unlock(&ibwdt_lock);
 }

 static int ibwdt_set_heartbeat(int t)
 {
 	if (t < 0 || t > 30)
 		return -EINVAL;

 	timeout = t;
 	return 0;
 }

 /*
  *	/dev/watchdog handling
  */

 static ssize_t ibwdt_write(struct file *file, const char __user *buf,
 						size_t count, loff_t *ppos)
 {
 	if (count) {
 		if (!nowayout) {
 			size_t i;

 			/* In case it was set long ago */
 			expect_close = 0;

 			for (i = 0; i != count; i++) {
 				char c;
 				if (get_user(c, buf + i))
 					return -EFAULT;
 				if (c == 'V')
 					expect_close = 42;
 			}
 		}
 		ibwdt_ping();
 	}
 	return count;
 }

 static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	int new_margin;
 	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 = "IB700 WDT",
 	};

 	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) {
 			ibwdt_disable();
 			retval = 0;
 		}
 		if (options & WDIOS_ENABLECARD) {
 			ibwdt_ping();
 			retval = 0;
 		}
 		return retval;
 	}
 	case WDIOC_KEEPALIVE:
 		ibwdt_ping();
 		break;

 	case WDIOC_SETTIMEOUT:
 		if (get_user(new_margin, p))
 			return -EFAULT;
 		if (ibwdt_set_heartbeat(new_margin))
 			return -EINVAL;
 		ibwdt_ping();
 		fallthrough;

 	case WDIOC_GETTIMEOUT:
 		return put_user(timeout, p);

 	default:
 		return -ENOTTY;
 	}
 	return 0;
 }

 static int ibwdt_open(struct inode *inode, struct file *file)
 {
 	if (test_and_set_bit(0, &ibwdt_is_open))
 		return -EBUSY;
 	if (nowayout)
 		__module_get(THIS_MODULE);

 	/* Activate */
 	ibwdt_ping();
 	return stream_open(inode, file);
 }

 static int ibwdt_close(struct inode *inode, struct file *file)
 {
 	if (expect_close == 42) {
 		ibwdt_disable();
 	} else {
 		pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 		ibwdt_ping();
 	}
 	clear_bit(0, &ibwdt_is_open);
 	expect_close = 0;
 	return 0;
 }

 /*
  *	Kernel Interfaces
  */

 static const struct file_operations ibwdt_fops = {
 	.owner		= THIS_MODULE,
 	.write		= ibwdt_write,
 	.unlocked_ioctl	= ibwdt_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
 	.open		= ibwdt_open,
 	.release	= ibwdt_close,
 };

 static struct miscdevice ibwdt_miscdev = {
 	.minor = WATCHDOG_MINOR,
 	.name = "watchdog",
 	.fops = &ibwdt_fops,
 };

 /*
  *	Init & exit routines
  */

 static int __init ibwdt_probe(struct platform_device *dev)
 {
 	int res;

 #if WDT_START != WDT_STOP
 	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
 		pr_err("STOP method I/O %X is not available\n", WDT_STOP);
 		res = -EIO;
 		goto out_nostopreg;
 	}
 #endif

 	if (!request_region(WDT_START, 1, "IB700 WDT")) {
 		pr_err("START method I/O %X is not available\n", WDT_START);
 		res = -EIO;
 		goto out_nostartreg;
 	}

 	/* Check that the heartbeat value is within it's range ;
 	 * if not reset to the default */
 	if (ibwdt_set_heartbeat(timeout)) {
 		ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
 		pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
 	}

 	res = misc_register(&ibwdt_miscdev);
 	if (res) {
 		pr_err("failed to register misc device\n");
 		goto out_nomisc;
 	}
 	return 0;

 out_nomisc:
 	release_region(WDT_START, 1);
 out_nostartreg:
 #if WDT_START != WDT_STOP
 	release_region(WDT_STOP, 1);
 #endif
 out_nostopreg:
 	return res;
 }

 static void ibwdt_remove(struct platform_device *dev)
 {
 	misc_deregister(&ibwdt_miscdev);
 	release_region(WDT_START, 1);
 #if WDT_START != WDT_STOP
 	release_region(WDT_STOP, 1);
 #endif
 }

 static void ibwdt_shutdown(struct platform_device *dev)
 {
 	/* Turn the WDT off if we have a soft shutdown */
 	ibwdt_disable();
 }

 static struct platform_driver ibwdt_driver = {
 	.remove_new	= ibwdt_remove,
 	.shutdown	= ibwdt_shutdown,
 	.driver		= {
 		.name	= DRV_NAME,
 	},
 };

 static int __init ibwdt_init(void)
 {
 	int err;

 	pr_info("WDT driver for IB700 single board computer initialising\n");

 	ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
 								-1, NULL, 0);
 	if (IS_ERR(ibwdt_platform_device))
 		return PTR_ERR(ibwdt_platform_device);

 	err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
 	if (err)
 		goto unreg_platform_device;

 	return 0;

 unreg_platform_device:
 	platform_device_unregister(ibwdt_platform_device);
 	return err;
 }

 static void __exit ibwdt_exit(void)
 {
 	platform_device_unregister(ibwdt_platform_device);
 	platform_driver_unregister(&ibwdt_driver);
 	pr_info("Watchdog Module Unloaded\n");
 }

 module_init(ibwdt_init);
 module_exit(ibwdt_exit);

 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
 MODULE_LICENSE("GPL");

 /* end of ib700wdt.c */
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* IB700 Single Board Computer WDT driver
	*
	* (c) Copyright 2001 Charles Howes <chowes@vsol.net>
	*
	* Based on advantechwdt.c which is based on acquirewdt.c which
	* is based on wdt.c.
	*
	* (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
	* Added timeout module option to override default
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/miscdevice.h>
	#include <linux/watchdog.h>
	#include <linux/ioport.h>
	#include <linux/fs.h>
	#include <linux/init.h>
	#include <linux/spinlock.h>
	#include <linux/moduleparam.h>
	#include <linux/platform_device.h>
	#include <linux/io.h>
	#include <linux/uaccess.h>


	static struct platform_device *ibwdt_platform_device;
	static unsigned long ibwdt_is_open;
	static DEFINE_SPINLOCK(ibwdt_lock);
	static char expect_close;

	/* Module information */
	#define DRV_NAME "ib700wdt"

	/*
	*
	* Watchdog Timer Configuration
	*
	* The function of the watchdog timer is to reset the system
	* automatically and is defined at I/O port 0443H. To enable the
	* watchdog timer and allow the system to reset, write I/O port 0443H.
	* To disable the timer, write I/O port 0441H for the system to stop the
	* watchdog function. The timer has a tolerance of 20% for its
	* intervals.
	*
	* The following describes how the timer should be programmed.
	*
	* Enabling Watchdog:
	* MOV AX,000FH (Choose the values from 0 to F)
	* MOV DX,0443H
	* OUT DX,AX
	*
	* Disabling Watchdog:
	* MOV AX,000FH (Any value is fine.)
	* MOV DX,0441H
	* OUT DX,AX
	*
	* Watchdog timer control table:
	* Level Value Time/sec \| Level Value Time/sec
	* 1 F 0 \| 9 7 16
	* 2 E 2 \| 10 6 18
	* 3 D 4 \| 11 5 20
	* 4 C 6 \| 12 4 22
	* 5 B 8 \| 13 3 24
	* 6 A 10 \| 14 2 26
	* 7 9 12 \| 15 1 28
	* 8 8 14 \| 16 0 30
	*
	*/

	#define WDT_STOP 0x441
	#define WDT_START 0x443

	/* Default timeout */
	#define WATCHDOG_TIMEOUT 30 /* 30 seconds +/- 20% */
	static int timeout = WATCHDOG_TIMEOUT; /* in seconds */
	module_param(timeout, int, 0);
	MODULE_PARM_DESC(timeout,
	"Watchdog timeout in seconds. 0<= timeout <=30, 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 ibwdt_ping(void)
	{
	int wd_margin = 15 - ((timeout + 1) / 2);

	spin_lock(&ibwdt_lock);

	/* Write a watchdog value */
	outb_p(wd_margin, WDT_START);

	spin_unlock(&ibwdt_lock);
	}

	static void ibwdt_disable(void)
	{
	spin_lock(&ibwdt_lock);
	outb_p(0, WDT_STOP);
	spin_unlock(&ibwdt_lock);
	}

	static int ibwdt_set_heartbeat(int t)
	{
	if (t < 0 \|\| t > 30)
	return -EINVAL;

	timeout = t;
	return 0;
	}

	/*
	* /dev/watchdog handling
	*/

	static ssize_t ibwdt_write(struct file file, const char __user buf,
	size_t count, loff_t *ppos)
	{
	if (count) {
	if (!nowayout) {
	size_t i;

	/* In case it was set long ago */
	expect_close = 0;

	for (i = 0; i != count; i++) {
	char c;
	if (get_user(c, buf + i))
	return -EFAULT;
	if (c == 'V')
	expect_close = 42;
	}
	}
	ibwdt_ping();
	}
	return count;
	}

	static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
	{
	int new_margin;
	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 = "IB700 WDT",
	};

	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) {
	ibwdt_disable();
	retval = 0;
	}
	if (options & WDIOS_ENABLECARD) {
	ibwdt_ping();
	retval = 0;
	}
	return retval;
	}
	case WDIOC_KEEPALIVE:
	ibwdt_ping();
	break;

	case WDIOC_SETTIMEOUT:
	if (get_user(new_margin, p))
	return -EFAULT;
	if (ibwdt_set_heartbeat(new_margin))
	return -EINVAL;
	ibwdt_ping();
	fallthrough;

	case WDIOC_GETTIMEOUT:
	return put_user(timeout, p);

	default:
	return -ENOTTY;
	}
	return 0;
	}

	static int ibwdt_open(struct inode inode, struct file file)
	{
	if (test_and_set_bit(0, &ibwdt_is_open))
	return -EBUSY;
	if (nowayout)
	__module_get(THIS_MODULE);

	/* Activate */
	ibwdt_ping();
	return stream_open(inode, file);
	}

	static int ibwdt_close(struct inode inode, struct file file)
	{
	if (expect_close == 42) {
	ibwdt_disable();
	} else {
	pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");
	ibwdt_ping();
	}
	clear_bit(0, &ibwdt_is_open);
	expect_close = 0;
	return 0;
	}

	/*
	* Kernel Interfaces
	*/

	static const struct file_operations ibwdt_fops = {
	.owner = THIS_MODULE,
	.write = ibwdt_write,
	.unlocked_ioctl = ibwdt_ioctl,
	.compat_ioctl = compat_ptr_ioctl,
	.open = ibwdt_open,
	.release = ibwdt_close,
	};

	static struct miscdevice ibwdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &ibwdt_fops,
	};

	/*
	* Init & exit routines
	*/

	static int __init ibwdt_probe(struct platform_device *dev)
	{
	int res;

	#if WDT_START != WDT_STOP
	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
	pr_err("STOP method I/O %X is not available\n", WDT_STOP);
	res = -EIO;
	goto out_nostopreg;
	}
	#endif

	if (!request_region(WDT_START, 1, "IB700 WDT")) {
	pr_err("START method I/O %X is not available\n", WDT_START);
	res = -EIO;
	goto out_nostartreg;
	}

	/* Check that the heartbeat value is within it's range ;
	* if not reset to the default */
	if (ibwdt_set_heartbeat(timeout)) {
	ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
	pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
	}

	res = misc_register(&ibwdt_miscdev);
	if (res) {
	pr_err("failed to register misc device\n");
	goto out_nomisc;
	}
	return 0;

	out_nomisc:
	release_region(WDT_START, 1);
	out_nostartreg:
	#if WDT_START != WDT_STOP
	release_region(WDT_STOP, 1);
	#endif
	out_nostopreg:
	return res;
	}

	static void ibwdt_remove(struct platform_device *dev)
	{
	misc_deregister(&ibwdt_miscdev);
	release_region(WDT_START, 1);
	#if WDT_START != WDT_STOP
	release_region(WDT_STOP, 1);
	#endif
	}

	static void ibwdt_shutdown(struct platform_device *dev)
	{
	/* Turn the WDT off if we have a soft shutdown */
	ibwdt_disable();
	}

	static struct platform_driver ibwdt_driver = {
	.remove_new = ibwdt_remove,
	.shutdown = ibwdt_shutdown,
	.driver = {
	.name = DRV_NAME,
	},
	};

	static int __init ibwdt_init(void)
	{
	int err;

	pr_info("WDT driver for IB700 single board computer initialising\n");

	ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
	-1, NULL, 0);
	if (IS_ERR(ibwdt_platform_device))
	return PTR_ERR(ibwdt_platform_device);

	err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
	if (err)
	goto unreg_platform_device;

	return 0;

	unreg_platform_device:
	platform_device_unregister(ibwdt_platform_device);
	return err;
	}

	static void __exit ibwdt_exit(void)
	{
	platform_device_unregister(ibwdt_platform_device);
	platform_driver_unregister(&ibwdt_driver);
	pr_info("Watchdog Module Unloaded\n");
	}

	module_init(ibwdt_init);
	module_exit(ibwdt_exit);

	MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
	MODULE_DESCRIPTION("IB700 SBC watchdog driver");
	MODULE_LICENSE("GPL");

	/* end of ib700wdt.c */