1 /* 2 * IndyDog 0.3 A Hardware Watchdog Device for SGI IP22 3 * 4 * (c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, 5 * All Rights Reserved. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * as published by the Free Software Foundation; either version 10 * 2 of the License, or (at your option) any later version. 11 * 12 * based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk> 13 */ 14 15 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 16 17 #include <linux/module.h> 18 #include <linux/moduleparam.h> 19 #include <linux/types.h> 20 #include <linux/kernel.h> 21 #include <linux/fs.h> 22 #include <linux/mm.h> 23 #include <linux/miscdevice.h> 24 #include <linux/watchdog.h> 25 #include <linux/notifier.h> 26 #include <linux/reboot.h> 27 #include <linux/init.h> 28 #include <linux/uaccess.h> 29 #include <asm/sgi/mc.h> 30 31 static unsigned long indydog_alive; 32 static DEFINE_SPINLOCK(indydog_lock); 33 34 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 35 36 static int nowayout = WATCHDOG_NOWAYOUT; 37 module_param(nowayout, int, 0); 38 MODULE_PARM_DESC(nowayout, 39 "Watchdog cannot be stopped once started (default=" 40 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 41 42 static void indydog_start(void) 43 { 44 u32 mc_ctrl0; 45 46 spin_lock(&indydog_lock); 47 mc_ctrl0 = sgimc->cpuctrl0; 48 mc_ctrl0 = sgimc->cpuctrl0 | SGIMC_CCTRL0_WDOG; 49 sgimc->cpuctrl0 = mc_ctrl0; 50 spin_unlock(&indydog_lock); 51 } 52 53 static void indydog_stop(void) 54 { 55 u32 mc_ctrl0; 56 57 spin_lock(&indydog_lock); 58 59 mc_ctrl0 = sgimc->cpuctrl0; 60 mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG; 61 sgimc->cpuctrl0 = mc_ctrl0; 62 spin_unlock(&indydog_lock); 63 64 pr_info("Stopped watchdog timer\n"); 65 } 66 67 static void indydog_ping(void) 68 { 69 sgimc->watchdogt = 0; 70 } 71 72 /* 73 * Allow only one person to hold it open 74 */ 75 static int indydog_open(struct inode *inode, struct file *file) 76 { 77 if (test_and_set_bit(0, &indydog_alive)) 78 return -EBUSY; 79 80 if (nowayout) 81 __module_get(THIS_MODULE); 82 83 /* Activate timer */ 84 indydog_start(); 85 indydog_ping(); 86 87 pr_info("Started watchdog timer\n"); 88 89 return nonseekable_open(inode, file); 90 } 91 92 static int indydog_release(struct inode *inode, struct file *file) 93 { 94 /* Shut off the timer. 95 * Lock it in if it's a module and we defined ...NOWAYOUT */ 96 if (!nowayout) 97 indydog_stop(); /* Turn the WDT off */ 98 clear_bit(0, &indydog_alive); 99 return 0; 100 } 101 102 static ssize_t indydog_write(struct file *file, const char *data, 103 size_t len, loff_t *ppos) 104 { 105 /* Refresh the timer. */ 106 if (len) 107 indydog_ping(); 108 return len; 109 } 110 111 static long indydog_ioctl(struct file *file, unsigned int cmd, 112 unsigned long arg) 113 { 114 int options, retval = -EINVAL; 115 static const struct watchdog_info ident = { 116 .options = WDIOF_KEEPALIVEPING, 117 .firmware_version = 0, 118 .identity = "Hardware Watchdog for SGI IP22", 119 }; 120 121 switch (cmd) { 122 case WDIOC_GETSUPPORT: 123 if (copy_to_user((struct watchdog_info *)arg, 124 &ident, sizeof(ident))) 125 return -EFAULT; 126 return 0; 127 case WDIOC_GETSTATUS: 128 case WDIOC_GETBOOTSTATUS: 129 return put_user(0, (int *)arg); 130 case WDIOC_SETOPTIONS: 131 { 132 if (get_user(options, (int *)arg)) 133 return -EFAULT; 134 if (options & WDIOS_DISABLECARD) { 135 indydog_stop(); 136 retval = 0; 137 } 138 if (options & WDIOS_ENABLECARD) { 139 indydog_start(); 140 retval = 0; 141 } 142 return retval; 143 } 144 case WDIOC_KEEPALIVE: 145 indydog_ping(); 146 return 0; 147 case WDIOC_GETTIMEOUT: 148 return put_user(WATCHDOG_TIMEOUT, (int *)arg); 149 default: 150 return -ENOTTY; 151 } 152 } 153 154 static int indydog_notify_sys(struct notifier_block *this, 155 unsigned long code, void *unused) 156 { 157 if (code == SYS_DOWN || code == SYS_HALT) 158 indydog_stop(); /* Turn the WDT off */ 159 160 return NOTIFY_DONE; 161 } 162 163 static const struct file_operations indydog_fops = { 164 .owner = THIS_MODULE, 165 .llseek = no_llseek, 166 .write = indydog_write, 167 .unlocked_ioctl = indydog_ioctl, 168 .open = indydog_open, 169 .release = indydog_release, 170 }; 171 172 static struct miscdevice indydog_miscdev = { 173 .minor = WATCHDOG_MINOR, 174 .name = "watchdog", 175 .fops = &indydog_fops, 176 }; 177 178 static struct notifier_block indydog_notifier = { 179 .notifier_call = indydog_notify_sys, 180 }; 181 182 static int __init watchdog_init(void) 183 { 184 int ret; 185 186 ret = register_reboot_notifier(&indydog_notifier); 187 if (ret) { 188 pr_err("cannot register reboot notifier (err=%d)\n", ret); 189 return ret; 190 } 191 192 ret = misc_register(&indydog_miscdev); 193 if (ret) { 194 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 195 WATCHDOG_MINOR, ret); 196 unregister_reboot_notifier(&indydog_notifier); 197 return ret; 198 } 199 200 pr_info("Hardware Watchdog Timer for SGI IP22: 0.3\n"); 201 202 return 0; 203 } 204 205 static void __exit watchdog_exit(void) 206 { 207 misc_deregister(&indydog_miscdev); 208 unregister_reboot_notifier(&indydog_notifier); 209 } 210 211 module_init(watchdog_init); 212 module_exit(watchdog_exit); 213 214 MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>"); 215 MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22"); 216 MODULE_LICENSE("GPL"); 217 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 218