Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/sparc-2.6
[deliverable/linux.git] / arch / um / drivers / harddog_kern.c
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 <asm/uaccess.h>
48 #include "mconsole.h"
49
50 MODULE_LICENSE("GPL");
51
52 /* Locked by the BKL in harddog_open and harddog_release */
53 static int timer_alive;
54 static int harddog_in_fd = -1;
55 static int harddog_out_fd = -1;
56
57 /*
58 * Allow only one person to hold it open
59 */
60
61 extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);
62
63 static int harddog_open(struct inode *inode, struct file *file)
64 {
65 int err;
66 char *sock = NULL;
67
68 lock_kernel();
69 if(timer_alive)
70 return -EBUSY;
71 #ifdef CONFIG_HARDDOG_NOWAYOUT
72 __module_get(THIS_MODULE);
73 #endif
74
75 #ifdef CONFIG_MCONSOLE
76 sock = mconsole_notify_socket();
77 #endif
78 err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
79 if(err) return(err);
80
81 timer_alive = 1;
82 unlock_kernel();
83 return nonseekable_open(inode, file);
84 }
85
86 extern void stop_watchdog(int in_fd, int out_fd);
87
88 static int harddog_release(struct inode *inode, struct file *file)
89 {
90 /*
91 * Shut off the timer.
92 */
93 lock_kernel();
94
95 stop_watchdog(harddog_in_fd, harddog_out_fd);
96 harddog_in_fd = -1;
97 harddog_out_fd = -1;
98
99 timer_alive=0;
100 unlock_kernel();
101 return 0;
102 }
103
104 extern int ping_watchdog(int fd);
105
106 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
107 loff_t *ppos)
108 {
109 /*
110 * Refresh the timer.
111 */
112 if(len)
113 return(ping_watchdog(harddog_out_fd));
114 return 0;
115 }
116
117 static int harddog_ioctl(struct inode *inode, struct file *file,
118 unsigned int cmd, unsigned long arg)
119 {
120 void __user *argp= (void __user *)arg;
121 static struct watchdog_info ident = {
122 WDIOC_SETTIMEOUT,
123 0,
124 "UML Hardware Watchdog"
125 };
126 switch (cmd) {
127 default:
128 return -ENOTTY;
129 case WDIOC_GETSUPPORT:
130 if(copy_to_user(argp, &ident, sizeof(ident)))
131 return -EFAULT;
132 return 0;
133 case WDIOC_GETSTATUS:
134 case WDIOC_GETBOOTSTATUS:
135 return put_user(0,(int __user *)argp);
136 case WDIOC_KEEPALIVE:
137 return(ping_watchdog(harddog_out_fd));
138 }
139 }
140
141 static struct file_operations harddog_fops = {
142 .owner = THIS_MODULE,
143 .write = harddog_write,
144 .ioctl = harddog_ioctl,
145 .open = harddog_open,
146 .release = harddog_release,
147 };
148
149 static struct miscdevice harddog_miscdev = {
150 .minor = WATCHDOG_MINOR,
151 .name = "watchdog",
152 .fops = &harddog_fops,
153 };
154
155 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n";
156
157 static int __init harddog_init(void)
158 {
159 int ret;
160
161 ret = misc_register(&harddog_miscdev);
162
163 if (ret)
164 return ret;
165
166 printk(banner);
167
168 return(0);
169 }
170
171 static void __exit harddog_exit(void)
172 {
173 misc_deregister(&harddog_miscdev);
174 }
175
176 module_init(harddog_init);
177 module_exit(harddog_exit);
178
179 /*
180 * Overrides for Emacs so that we follow Linus's tabbing style.
181 * Emacs will notice this stuff at the end of the file and automatically
182 * adjust the settings for this buffer only. This must remain at the end
183 * of the file.
184 * ---------------------------------------------------------------------------
185 * Local variables:
186 * c-file-style: "linux"
187 * End:
188 */
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