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.
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.
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>
32 * Added soft_noboot; Allows testing the softdog trigger without
33 * requiring a recompile.
34 * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
35 */
36
37 #include <linux/module.h>
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>
45 #include <linux/mutex.h>
46 #include <linux/init.h>
47 #include <linux/spinlock.h>
48 #include <linux/uaccess.h>
49 #include "mconsole.h"
50
51 MODULE_LICENSE("GPL");
52
53 static DEFINE_MUTEX(harddog_mutex);
54 static DEFINE_SPINLOCK(lock);
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 */
62
63 extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);
64
harddog_open(struct inode * inode,struct file * file)65 static int harddog_open(struct inode *inode, struct file *file)
66 {
67 int err = -EBUSY;
68 char *sock = NULL;
69
70 mutex_lock(&harddog_mutex);
71 spin_lock(&lock);
72 if(timer_alive)
73 goto err;
74 #ifdef CONFIG_WATCHDOG_NOWAYOUT
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);
82 if(err)
83 goto err;
84
85 timer_alive = 1;
86 spin_unlock(&lock);
87 mutex_unlock(&harddog_mutex);
88 return stream_open(inode, file);
89 err:
90 spin_unlock(&lock);
91 mutex_unlock(&harddog_mutex);
92 return err;
93 }
94
95 extern void stop_watchdog(int in_fd, int out_fd);
96
harddog_release(struct inode * inode,struct file * file)97 static int harddog_release(struct inode *inode, struct file *file)
98 {
99 /*
100 * Shut off the timer.
101 */
102
103 spin_lock(&lock);
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;
110 spin_unlock(&lock);
111
112 return 0;
113 }
114
115 extern int ping_watchdog(int fd);
116
harddog_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)117 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
118 loff_t *ppos)
119 {
120 /*
121 * Refresh the timer.
122 */
123 if(len)
124 return ping_watchdog(harddog_out_fd);
125 return 0;
126 }
127
harddog_ioctl_unlocked(struct file * file,unsigned int cmd,unsigned long arg)128 static int harddog_ioctl_unlocked(struct file *file,
129 unsigned int cmd, unsigned long arg)
130 {
131 void __user *argp= (void __user *)arg;
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:
141 if(copy_to_user(argp, &ident, sizeof(ident)))
142 return -EFAULT;
143 return 0;
144 case WDIOC_GETSTATUS:
145 case WDIOC_GETBOOTSTATUS:
146 return put_user(0,(int __user *)argp);
147 case WDIOC_KEEPALIVE:
148 return ping_watchdog(harddog_out_fd);
149 }
150 }
151
harddog_ioctl(struct file * file,unsigned int cmd,unsigned long arg)152 static long harddog_ioctl(struct file *file,
153 unsigned int cmd, unsigned long arg)
154 {
155 long ret;
156
157 mutex_lock(&harddog_mutex);
158 ret = harddog_ioctl_unlocked(file, cmd, arg);
159 mutex_unlock(&harddog_mutex);
160
161 return ret;
162 }
163
164 static const struct file_operations harddog_fops = {
165 .owner = THIS_MODULE,
166 .write = harddog_write,
167 .unlocked_ioctl = harddog_ioctl,
168 .compat_ioctl = compat_ptr_ioctl,
169 .open = harddog_open,
170 .release = harddog_release,
171 .llseek = no_llseek,
172 };
173
174 static struct miscdevice harddog_miscdev = {
175 .minor = WATCHDOG_MINOR,
176 .name = "watchdog",
177 .fops = &harddog_fops,
178 };
179 module_misc_device(harddog_miscdev);
180