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 | #include "harddog.h" |
51 | |
52 | MODULE_LICENSE("GPL" ); |
53 | |
54 | static DEFINE_MUTEX(harddog_mutex); |
55 | static DEFINE_SPINLOCK(lock); |
56 | static int timer_alive; |
57 | static int harddog_in_fd = -1; |
58 | static int harddog_out_fd = -1; |
59 | |
60 | /* |
61 | * Allow only one person to hold it open |
62 | */ |
63 | |
64 | static int harddog_open(struct inode *inode, struct file *file) |
65 | { |
66 | int err = -EBUSY; |
67 | char *sock = NULL; |
68 | |
69 | mutex_lock(&harddog_mutex); |
70 | spin_lock(lock: &lock); |
71 | if(timer_alive) |
72 | goto err; |
73 | #ifdef CONFIG_WATCHDOG_NOWAYOUT |
74 | __module_get(THIS_MODULE); |
75 | #endif |
76 | |
77 | #ifdef CONFIG_MCONSOLE |
78 | sock = mconsole_notify_socket(); |
79 | #endif |
80 | err = start_watchdog(in_fd_ret: &harddog_in_fd, out_fd_ret: &harddog_out_fd, sock); |
81 | if(err) |
82 | goto err; |
83 | |
84 | timer_alive = 1; |
85 | spin_unlock(lock: &lock); |
86 | mutex_unlock(lock: &harddog_mutex); |
87 | return stream_open(inode, filp: file); |
88 | err: |
89 | spin_unlock(lock: &lock); |
90 | mutex_unlock(lock: &harddog_mutex); |
91 | return err; |
92 | } |
93 | |
94 | static int harddog_release(struct inode *inode, struct file *file) |
95 | { |
96 | /* |
97 | * Shut off the timer. |
98 | */ |
99 | |
100 | spin_lock(lock: &lock); |
101 | |
102 | stop_watchdog(in_fd: harddog_in_fd, out_fd: harddog_out_fd); |
103 | harddog_in_fd = -1; |
104 | harddog_out_fd = -1; |
105 | |
106 | timer_alive=0; |
107 | spin_unlock(lock: &lock); |
108 | |
109 | return 0; |
110 | } |
111 | |
112 | static ssize_t harddog_write(struct file *file, const char __user *data, size_t len, |
113 | loff_t *ppos) |
114 | { |
115 | /* |
116 | * Refresh the timer. |
117 | */ |
118 | if(len) |
119 | return ping_watchdog(fd: harddog_out_fd); |
120 | return 0; |
121 | } |
122 | |
123 | static int harddog_ioctl_unlocked(struct file *file, |
124 | unsigned int cmd, unsigned long arg) |
125 | { |
126 | void __user *argp= (void __user *)arg; |
127 | static struct watchdog_info ident = { |
128 | WDIOC_SETTIMEOUT, |
129 | 0, |
130 | "UML Hardware Watchdog" |
131 | }; |
132 | switch (cmd) { |
133 | default: |
134 | return -ENOTTY; |
135 | case WDIOC_GETSUPPORT: |
136 | if(copy_to_user(to: argp, from: &ident, n: sizeof(ident))) |
137 | return -EFAULT; |
138 | return 0; |
139 | case WDIOC_GETSTATUS: |
140 | case WDIOC_GETBOOTSTATUS: |
141 | return put_user(0,(int __user *)argp); |
142 | case WDIOC_KEEPALIVE: |
143 | return ping_watchdog(fd: harddog_out_fd); |
144 | } |
145 | } |
146 | |
147 | static long harddog_ioctl(struct file *file, |
148 | unsigned int cmd, unsigned long arg) |
149 | { |
150 | long ret; |
151 | |
152 | mutex_lock(&harddog_mutex); |
153 | ret = harddog_ioctl_unlocked(file, cmd, arg); |
154 | mutex_unlock(lock: &harddog_mutex); |
155 | |
156 | return ret; |
157 | } |
158 | |
159 | static const struct file_operations harddog_fops = { |
160 | .owner = THIS_MODULE, |
161 | .write = harddog_write, |
162 | .unlocked_ioctl = harddog_ioctl, |
163 | .compat_ioctl = compat_ptr_ioctl, |
164 | .open = harddog_open, |
165 | .release = harddog_release, |
166 | .llseek = no_llseek, |
167 | }; |
168 | |
169 | static struct miscdevice harddog_miscdev = { |
170 | .minor = WATCHDOG_MINOR, |
171 | .name = "watchdog" , |
172 | .fops = &harddog_fops, |
173 | }; |
174 | module_misc_device(harddog_miscdev); |
175 | |