tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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/smp_lock.h>
46#include <linux/init.h>
47#include <linux/spinlock.h>
48#include <asm/uaccess.h>
49#include "mconsole.h"
50
51MODULE_LICENSE("GPL");
52
53static DEFINE_SPINLOCK(lock);
54static int timer_alive;
55static int harddog_in_fd = -1;
56static int harddog_out_fd = -1;
57
58/*
59 * Allow only one person to hold it open
60 */
61
62extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);
63
64static int harddog_open(struct inode *inode, struct file *file)
65{
66 int err = -EBUSY;
67 char *sock = NULL;
68
69 lock_kernel();
70 spin_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(&harddog_in_fd, &harddog_out_fd, sock);
81 if(err)
82 goto err;
83
84 timer_alive = 1;
85 spin_unlock(&lock);
86 unlock_kernel();
87 return nonseekable_open(inode, file);
88err:
89 spin_unlock(&lock);
90 unlock_kernel();
91 return err;
92}
93
94extern void stop_watchdog(int in_fd, int out_fd);
95
96static int harddog_release(struct inode *inode, struct file *file)
97{
98 /*
99 * Shut off the timer.
100 */
101
102 spin_lock(&lock);
103
104 stop_watchdog(harddog_in_fd, harddog_out_fd);
105 harddog_in_fd = -1;
106 harddog_out_fd = -1;
107
108 timer_alive=0;
109 spin_unlock(&lock);
110
111 return 0;
112}
113
114extern int ping_watchdog(int fd);
115
116static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
117 loff_t *ppos)
118{
119 /*
120 * Refresh the timer.
121 */
122 if(len)
123 return ping_watchdog(harddog_out_fd);
124 return 0;
125}
126
127static int harddog_ioctl_unlocked(struct file *file,
128 unsigned int cmd, unsigned long arg)
129{
130 void __user *argp= (void __user *)arg;
131 static struct watchdog_info ident = {
132 WDIOC_SETTIMEOUT,
133 0,
134 "UML Hardware Watchdog"
135 };
136 switch (cmd) {
137 default:
138 return -ENOTTY;
139 case WDIOC_GETSUPPORT:
140 if(copy_to_user(argp, &ident, sizeof(ident)))
141 return -EFAULT;
142 return 0;
143 case WDIOC_GETSTATUS:
144 case WDIOC_GETBOOTSTATUS:
145 return put_user(0,(int __user *)argp);
146 case WDIOC_KEEPALIVE:
147 return ping_watchdog(harddog_out_fd);
148 }
149}
150
151static long harddog_ioctl(struct file *file,
152 unsigned int cmd, unsigned long arg)
153{
154 long ret;
155
156 lock_kernel();
157 ret = harddog_ioctl_unlocked(file, cmd, arg);
158 unlock_kernel();
159
160 return ret;
161}
162
163static const struct file_operations harddog_fops = {
164 .owner = THIS_MODULE,
165 .write = harddog_write,
166 .unlocked_ioctl = harddog_ioctl,
167 .open = harddog_open,
168 .release = harddog_release,
169};
170
171static struct miscdevice harddog_miscdev = {
172 .minor = WATCHDOG_MINOR,
173 .name = "watchdog",
174 .fops = &harddog_fops,
175};
176
177static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n";
178
179static int __init harddog_init(void)
180{
181 int ret;
182
183 ret = misc_register(&harddog_miscdev);
184
185 if (ret)
186 return ret;
187
188 printk(banner);
189
190 return 0;
191}
192
193static void __exit harddog_exit(void)
194{
195 misc_deregister(&harddog_miscdev);
196}
197
198module_init(harddog_init);
199module_exit(harddog_exit);