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/config.h> 39 #include <linux/types.h> 40 #include <linux/kernel.h> 41 #include <linux/fs.h> 42 #include <linux/mm.h> 43 #include <linux/miscdevice.h> 44 #include <linux/watchdog.h> 45 #include <linux/reboot.h> 46 #include <linux/smp_lock.h> 47 #include <linux/init.h> 48 #include <asm/uaccess.h> 49 #include "mconsole.h" 50 51 MODULE_LICENSE("GPL"); 52 53 /* Locked by the BKL in harddog_open and harddog_release */ 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; 67 char *sock = NULL; 68 69 lock_kernel(); 70 if(timer_alive) 71 return -EBUSY; 72 #ifdef CONFIG_HARDDOG_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) return(err); 81 82 timer_alive = 1; 83 unlock_kernel(); 84 return nonseekable_open(inode, file); 85 } 86 87 extern void stop_watchdog(int in_fd, int out_fd); 88 89 static int harddog_release(struct inode *inode, struct file *file) 90 { 91 /* 92 * Shut off the timer. 93 */ 94 lock_kernel(); 95 96 stop_watchdog(harddog_in_fd, harddog_out_fd); 97 harddog_in_fd = -1; 98 harddog_out_fd = -1; 99 100 timer_alive=0; 101 unlock_kernel(); 102 return 0; 103 } 104 105 extern int ping_watchdog(int fd); 106 107 static ssize_t harddog_write(struct file *file, const char *data, size_t len, 108 loff_t *ppos) 109 { 110 /* 111 * Refresh the timer. 112 */ 113 if(len) 114 return(ping_watchdog(harddog_out_fd)); 115 return 0; 116 } 117 118 static int harddog_ioctl(struct inode *inode, struct file *file, 119 unsigned int cmd, unsigned long arg) 120 { 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((struct harddog_info *)arg, &ident, 131 sizeof(ident))) 132 return -EFAULT; 133 return 0; 134 case WDIOC_GETSTATUS: 135 case WDIOC_GETBOOTSTATUS: 136 return put_user(0,(int *)arg); 137 case WDIOC_KEEPALIVE: 138 return(ping_watchdog(harddog_out_fd)); 139 } 140 } 141 142 static struct file_operations harddog_fops = { 143 .owner = THIS_MODULE, 144 .write = harddog_write, 145 .ioctl = harddog_ioctl, 146 .open = harddog_open, 147 .release = harddog_release, 148 }; 149 150 static struct miscdevice harddog_miscdev = { 151 .minor = WATCHDOG_MINOR, 152 .name = "watchdog", 153 .fops = &harddog_fops, 154 }; 155 156 static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n"; 157 158 static int __init harddog_init(void) 159 { 160 int ret; 161 162 ret = misc_register(&harddog_miscdev); 163 164 if (ret) 165 return ret; 166 167 printk(banner); 168 169 return(0); 170 } 171 172 static void __exit harddog_exit(void) 173 { 174 misc_deregister(&harddog_miscdev); 175 } 176 177 module_init(harddog_init); 178 module_exit(harddog_exit); 179 180 /* 181 * Overrides for Emacs so that we follow Linus's tabbing style. 182 * Emacs will notice this stuff at the end of the file and automatically 183 * adjust the settings for this buffer only. This must remain at the end 184 * of the file. 185 * --------------------------------------------------------------------------- 186 * Local variables: 187 * c-file-style: "linux" 188 * End: 189 */ 190