[mirror_ubuntu-bionic-kernel.git] / arch / um / drivers / harddog_kern.c

/* UML hardware watchdog, shamelessly stolen from:
 *
 *	SoftDog	0.05:	A Software Watchdog Device
 *
 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *				http://www.redhat.com
 *
 *	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 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>
 *
 *	Software only watchdog driver. Unlike its big brother the WDT501P
 *	driver this won't always recover a failed machine.
 *
 *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
 *	Modularised.
 *	Added soft_margin; use upon insmod to change the timer delay.
 *	NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
 *	    minors.
 *
 *  19980911 Alan Cox
 *	Made SMP safe for 2.3.x
 *
 *  20011127 Joel Becker (jlbec@evilplan.org>
 *	Added soft_noboot; Allows testing the softdog trigger without
 *	requiring a recompile.
 *	Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
 */

#include <linux/module.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/mutex.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include "mconsole.h"

MODULE_LICENSE("GPL");

static DEFINE_MUTEX(harddog_mutex);
static DEFINE_SPINLOCK(lock);
static int timer_alive;
static int harddog_in_fd = -1;
static int harddog_out_fd = -1;

/*
 *	Allow only one person to hold it open
 */

extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);

static int harddog_open(struct inode *inode, struct file *file)
{
	int err = -EBUSY;
	char *sock = NULL;

	mutex_lock(&harddog_mutex);
	spin_lock(&lock);
	if(timer_alive)
		goto err;
#ifdef CONFIG_WATCHDOG_NOWAYOUT
	__module_get(THIS_MODULE);
#endif

#ifdef CONFIG_MCONSOLE
	sock = mconsole_notify_socket();
#endif
	err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
	if(err)
		goto err;

	timer_alive = 1;
	spin_unlock(&lock);
	mutex_unlock(&harddog_mutex);
	return nonseekable_open(inode, file);
err:
	spin_unlock(&lock);
	mutex_unlock(&harddog_mutex);
	return err;
}

extern void stop_watchdog(int in_fd, int out_fd);

static int harddog_release(struct inode *inode, struct file *file)
{
	/*
	 *	Shut off the timer.
	 */

	spin_lock(&lock);

	stop_watchdog(harddog_in_fd, harddog_out_fd);
	harddog_in_fd = -1;
	harddog_out_fd = -1;

	timer_alive=0;
	spin_unlock(&lock);

	return 0;
}

extern int ping_watchdog(int fd);

static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
			     loff_t *ppos)
{
	/*
	 *	Refresh the timer.
	 */
	if(len)
		return ping_watchdog(harddog_out_fd);
	return 0;
}

static int harddog_ioctl_unlocked(struct file *file,
				  unsigned int cmd, unsigned long arg)
{
	void __user *argp= (void __user *)arg;
	static struct watchdog_info ident = {
		WDIOC_SETTIMEOUT,
		0,
		"UML Hardware Watchdog"
	};
	switch (cmd) {
		default:
			return -ENOTTY;
		case WDIOC_GETSUPPORT:
			if(copy_to_user(argp, &ident, sizeof(ident)))
				return -EFAULT;
			return 0;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0,(int __user *)argp);
		case WDIOC_KEEPALIVE:
			return ping_watchdog(harddog_out_fd);
	}
}

static long harddog_ioctl(struct file *file,
			  unsigned int cmd, unsigned long arg)
{
	long ret;

	mutex_lock(&harddog_mutex);
	ret = harddog_ioctl_unlocked(file, cmd, arg);
	mutex_unlock(&harddog_mutex);

	return ret;
}

static const struct file_operations harddog_fops = {
	.owner		= THIS_MODULE,
	.write		= harddog_write,
	.unlocked_ioctl	= harddog_ioctl,
	.open		= harddog_open,
	.release	= harddog_release,
	.llseek		= no_llseek,
};

static struct miscdevice harddog_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &harddog_fops,
};
module_misc_device(harddog_miscdev);
Commit	Line	Data
1da177e4 LT	1	/* UML hardware watchdog, shamelessly stolen from:
	2	*
	3	* SoftDog 0.05: A Software Watchdog Device
	4	*
	5	* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
	6	* http://www.redhat.com
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License
	10	* as published by the Free Software Foundation; either version
	11	* 2 of the License, or (at your option) any later version.
5bbcbeca JD	12	*
	13	* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
	14	* warranty for any of this software. This material is provided
	15	* "AS-IS" and at no charge.
1da177e4 LT	16	*
	17	* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
	18	*
	19	* Software only watchdog driver. Unlike its big brother the WDT501P
	20	* driver this won't always recover a failed machine.
	21	*
	22	* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
	23	* Modularised.
	24	* Added soft_margin; use upon insmod to change the timer delay.
	25	* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
	26	* minors.
	27	*
	28	* 19980911 Alan Cox
	29	* Made SMP safe for 2.3.x
	30	*
	31	* 20011127 Joel Becker (jlbec@evilplan.org>
5bbcbeca	32	* Added soft_noboot; Allows testing the softdog trigger without
1da177e4 LT	33	* requiring a recompile.
	34	* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
	35	*/
5bbcbeca	36
1da177e4	37	#include <linux/module.h>
1da177e4 LT	38	#include <linux/types.h>
	39	#include <linux/kernel.h>
	40	#include <linux/fs.h>
	41	#include <linux/mm.h>
	42	#include <linux/miscdevice.h>
	43	#include <linux/watchdog.h>
	44	#include <linux/reboot.h>
9a181c58	45	#include <linux/mutex.h>
1da177e4	46	#include <linux/init.h>
42d36115	47	#include <linux/spinlock.h>
7c0f6ba6	48	#include <linux/uaccess.h>
1da177e4 LT	49	#include "mconsole.h"
	50
	51	MODULE_LICENSE("GPL");
	52
9a181c58	53	static DEFINE_MUTEX(harddog_mutex);
42d36115	54	static DEFINE_SPINLOCK(lock);
1da177e4 LT	55	static int timer_alive;
	56	static int harddog_in_fd = -1;
	57	static int harddog_out_fd = -1;
	58
	59	/*
	60	* Allow only one person to hold it open
	61	*/
5bbcbeca	62
1da177e4 LT	63	extern int start_watchdog(int in_fd_ret, int out_fd_ret, char *sock);
	64
	65	static int harddog_open(struct inode inode, struct file file)
	66	{
42d36115	67	int err = -EBUSY;
1da177e4 LT	68	char *sock = NULL;
1da177e4 LT	69
9a181c58	70	mutex_lock(&harddog_mutex);
42d36115	71	spin_lock(&lock);
1da177e4	72	if(timer_alive)
42d36115	73	goto err;
8d820760	74	#ifdef CONFIG_WATCHDOG_NOWAYOUT
1da177e4 LT	75	__module_get(THIS_MODULE);
	76	#endif
	77
	78	#ifdef CONFIG_MCONSOLE
	79	sock = mconsole_notify_socket();
	80	#endif
	81	err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
42d36115 JD	82	if(err)
42d36115 JD	83	goto err;
1da177e4 LT	84
1da177e4 LT	85	timer_alive = 1;
42d36115	86	spin_unlock(&lock);
9a181c58	87	mutex_unlock(&harddog_mutex);
1da177e4	88	return nonseekable_open(inode, file);
42d36115 JD	89	err:
42d36115 JD	90	spin_unlock(&lock);
9a181c58	91	mutex_unlock(&harddog_mutex);
42d36115	92	return err;
1da177e4 LT	93	}
	94
	95	extern void stop_watchdog(int in_fd, int out_fd);
	96
	97	static int harddog_release(struct inode inode, struct file file)
	98	{
	99	/*
	100	* Shut off the timer.
	101	*/
42d36115 JD	102
42d36115 JD	103	spin_lock(&lock);
1da177e4 LT	104
	105	stop_watchdog(harddog_in_fd, harddog_out_fd);
	106	harddog_in_fd = -1;
	107	harddog_out_fd = -1;
	108
	109	timer_alive=0;
42d36115 JD	110	spin_unlock(&lock);
42d36115 JD	111
1da177e4 LT	112	return 0;
	113	}
	114
	115	extern int ping_watchdog(int fd);
	116
4d338e1a	117	static ssize_t harddog_write(struct file file, const char __user data, size_t len,
1da177e4 LT	118	loff_t *ppos)
	119	{
	120	/*
	121	* Refresh the timer.
	122	*/
	123	if(len)
5bbcbeca	124	return ping_watchdog(harddog_out_fd);
1da177e4 LT	125	return 0;
	126	}
	127
9f37af65 FW	128	static int harddog_ioctl_unlocked(struct file *file,
9f37af65 FW	129	unsigned int cmd, unsigned long arg)
1da177e4	130	{
4d338e1a	131	void __user argp= (void __user )arg;
1da177e4 LT	132	static struct watchdog_info ident = {
	133	WDIOC_SETTIMEOUT,
	134	0,
	135	"UML Hardware Watchdog"
	136	};
	137	switch (cmd) {
	138	default:
	139	return -ENOTTY;
	140	case WDIOC_GETSUPPORT:
4d338e1a	141	if(copy_to_user(argp, &ident, sizeof(ident)))
1da177e4 LT	142	return -EFAULT;
	143	return 0;
	144	case WDIOC_GETSTATUS:
	145	case WDIOC_GETBOOTSTATUS:
4d338e1a	146	return put_user(0,(int __user *)argp);
1da177e4	147	case WDIOC_KEEPALIVE:
5bbcbeca	148	return ping_watchdog(harddog_out_fd);
1da177e4 LT	149	}
	150	}
	151
9f37af65 FW	152	static long harddog_ioctl(struct file *file,
	153	unsigned int cmd, unsigned long arg)
	154	{
	155	long ret;
	156
9a181c58	157	mutex_lock(&harddog_mutex);
9f37af65	158	ret = harddog_ioctl_unlocked(file, cmd, arg);
9a181c58	159	mutex_unlock(&harddog_mutex);
9f37af65 FW	160
	161	return ret;
	162	}
	163
5dfe4c96	164	static const struct file_operations harddog_fops = {
1da177e4 LT	165	.owner = THIS_MODULE,
1da177e4 LT	166	.write = harddog_write,
9f37af65	167	.unlocked_ioctl = harddog_ioctl,
1da177e4 LT	168	.open = harddog_open,
1da177e4 LT	169	.release = harddog_release,
6038f373	170	.llseek = no_llseek,
1da177e4 LT	171	};
	172
	173	static struct miscdevice harddog_miscdev = {
	174	.minor = WATCHDOG_MINOR,
	175	.name = "watchdog",
	176	.fops = &harddog_fops,
	177	};
d6a38c0b	178	module_misc_device(harddog_miscdev);