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 51 MODULE_LICENSE("GPL"); 52 53 static DEFINE_SPINLOCK(lock); 54 static int timer_alive; 55 static int harddog_in_fd = -1; 56 static int harddog_out_fd = -1; 57 58 /* 59 * Allow only one person to hold it open 60 */ 61 62 extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock); 63 64 static int harddog_open(struct inode *inode, struct file *file) 65 { 66 int err = -EBUSY; 67 char *sock = NULL; 68 69 spin_lock(&lock); 70 if(timer_alive) 71 goto err; 72 #ifdef CONFIG_WATCHDOG_NOWAYOUT 73 __module_get(THIS_MODULE); 74 #endif 75 76 #ifdef CONFIG_MCONSOLE 77 sock = mconsole_notify_socket(); 78 #endif 79 err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock); 80 if(err) 81 goto err; 82 83 timer_alive = 1; 84 spin_unlock(&lock); 85 return nonseekable_open(inode, file); 86 err: 87 spin_unlock(&lock); 88 return err; 89 } 90 91 extern void stop_watchdog(int in_fd, int out_fd); 92 93 static int harddog_release(struct inode *inode, struct file *file) 94 { 95 /* 96 * Shut off the timer. 97 */ 98 99 spin_lock(&lock); 100 101 stop_watchdog(harddog_in_fd, harddog_out_fd); 102 harddog_in_fd = -1; 103 harddog_out_fd = -1; 104 105 timer_alive=0; 106 spin_unlock(&lock); 107 108 return 0; 109 } 110 111 extern int ping_watchdog(int fd); 112 113 static ssize_t harddog_write(struct file *file, const char __user *data, size_t len, 114 loff_t *ppos) 115 { 116 /* 117 * Refresh the timer. 118 */ 119 if(len) 120 return ping_watchdog(harddog_out_fd); 121 return 0; 122 } 123 124 static int harddog_ioctl(struct inode *inode, struct file *file, 125 unsigned int cmd, unsigned long arg) 126 { 127 void __user *argp= (void __user *)arg; 128 static struct watchdog_info ident = { 129 WDIOC_SETTIMEOUT, 130 0, 131 "UML Hardware Watchdog" 132 }; 133 switch (cmd) { 134 default: 135 return -ENOTTY; 136 case WDIOC_GETSUPPORT: 137 if(copy_to_user(argp, &ident, sizeof(ident))) 138 return -EFAULT; 139 return 0; 140 case WDIOC_GETSTATUS: 141 case WDIOC_GETBOOTSTATUS: 142 return put_user(0,(int __user *)argp); 143 case WDIOC_KEEPALIVE: 144 return ping_watchdog(harddog_out_fd); 145 } 146 } 147 148 static const struct file_operations harddog_fops = { 149 .owner = THIS_MODULE, 150 .write = harddog_write, 151 .ioctl = harddog_ioctl, 152 .open = harddog_open, 153 .release = harddog_release, 154 }; 155 156 static struct miscdevice harddog_miscdev = { 157 .minor = WATCHDOG_MINOR, 158 .name = "watchdog", 159 .fops = &harddog_fops, 160 }; 161 162 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n"; 163 164 static int __init harddog_init(void) 165 { 166 int ret; 167 168 ret = misc_register(&harddog_miscdev); 169 170 if (ret) 171 return ret; 172 173 printk(banner); 174 175 return 0; 176 } 177 178 static void __exit harddog_exit(void) 179 { 180 misc_deregister(&harddog_miscdev); 181 } 182 183 module_init(harddog_init); 184 module_exit(harddog_exit); 185