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); 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 mutex_unlock(&harddog_mutex); 87 return stream_open(inode, file); 88 err: 89 spin_unlock(&lock); 90 mutex_unlock(&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); 101 102 stop_watchdog(harddog_in_fd, harddog_out_fd); 103 harddog_in_fd = -1; 104 harddog_out_fd = -1; 105 106 timer_alive=0; 107 spin_unlock(&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(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(argp, &ident, 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(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(&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