1/* drivers/char/watchdog/scx200_wdt.c 2 3 National Semiconductor SCx200 Watchdog support 4 5 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> 6 7 Some code taken from: 8 National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver 9 (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com> 10 11 This program is free software; you can redistribute it and/or 12 modify it under the terms of the GNU General Public License as 13 published by the Free Software Foundation; either version 2 of the 14 License, or (at your option) any later version. 15 16 The author(s) of this software shall not be held liable for damages 17 of any nature resulting due to the use of this software. This 18 software is provided AS-IS with no warranties. */ 19 20#include <linux/module.h> 21#include <linux/moduleparam.h> 22#include <linux/init.h> 23#include <linux/miscdevice.h> 24#include <linux/watchdog.h> 25#include <linux/notifier.h> 26#include <linux/reboot.h> 27#include <linux/fs.h> 28#include <linux/ioport.h> 29#include <linux/scx200.h> 30#include <linux/uaccess.h> 31#include <linux/io.h> 32 33#define NAME "scx200_wdt" 34 35MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); 36MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver"); 37MODULE_LICENSE("GPL"); 38MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 39 40static int margin = 60; /* in seconds */ 41module_param(margin, int, 0); 42MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 43 44static int nowayout = WATCHDOG_NOWAYOUT; 45module_param(nowayout, int, 0); 46MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 47 48static u16 wdto_restart; 49static char expect_close; 50static unsigned long open_lock; 51static DEFINE_SPINLOCK(scx_lock); 52 53/* Bits of the WDCNFG register */ 54#define W_ENABLE 0x00fa /* Enable watchdog */ 55#define W_DISABLE 0x0000 /* Disable watchdog */ 56 57/* The scaling factor for the timer, this depends on the value of W_ENABLE */ 58#define W_SCALE (32768/1024) 59 60static void scx200_wdt_ping(void) 61{ 62 spin_lock(&scx_lock); 63 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO); 64 spin_unlock(&scx_lock); 65} 66 67static void scx200_wdt_update_margin(void) 68{ 69 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin); 70 wdto_restart = margin * W_SCALE; 71} 72 73static void scx200_wdt_enable(void) 74{ 75 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n", 76 wdto_restart); 77 78 spin_lock(&scx_lock); 79 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 80 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 81 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 82 spin_unlock(&scx_lock); 83 84 scx200_wdt_ping(); 85} 86 87static void scx200_wdt_disable(void) 88{ 89 printk(KERN_DEBUG NAME ": disabling watchdog timer\n"); 90 91 spin_lock(&scx_lock); 92 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 93 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 94 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 95 spin_unlock(&scx_lock); 96} 97 98static int scx200_wdt_open(struct inode *inode, struct file *file) 99{ 100 /* only allow one at a time */ 101 if (test_and_set_bit(0, &open_lock)) 102 return -EBUSY; 103 scx200_wdt_enable(); 104 105 return nonseekable_open(inode, file); 106} 107 108static int scx200_wdt_release(struct inode *inode, struct file *file) 109{ 110 if (expect_close != 42) 111 printk(KERN_WARNING NAME 112 ": watchdog device closed unexpectedly, " 113 "will not disable the watchdog timer\n"); 114 else if (!nowayout) 115 scx200_wdt_disable(); 116 expect_close = 0; 117 clear_bit(0, &open_lock); 118 119 return 0; 120} 121 122static int scx200_wdt_notify_sys(struct notifier_block *this, 123 unsigned long code, void *unused) 124{ 125 if (code == SYS_HALT || code == SYS_POWER_OFF) 126 if (!nowayout) 127 scx200_wdt_disable(); 128 129 return NOTIFY_DONE; 130} 131 132static struct notifier_block scx200_wdt_notifier = { 133 .notifier_call = scx200_wdt_notify_sys, 134}; 135 136static ssize_t scx200_wdt_write(struct file *file, const char __user *data, 137 size_t len, loff_t *ppos) 138{ 139 /* check for a magic close character */ 140 if (len) { 141 size_t i; 142 143 scx200_wdt_ping(); 144 145 expect_close = 0; 146 for (i = 0; i < len; ++i) { 147 char c; 148 if (get_user(c, data + i)) 149 return -EFAULT; 150 if (c == 'V') 151 expect_close = 42; 152 } 153 154 return len; 155 } 156 157 return 0; 158} 159 160static long scx200_wdt_ioctl(struct file *file, unsigned int cmd, 161 unsigned long arg) 162{ 163 void __user *argp = (void __user *)arg; 164 int __user *p = argp; 165 static const struct watchdog_info ident = { 166 .identity = "NatSemi SCx200 Watchdog", 167 .firmware_version = 1, 168 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 169 WDIOF_MAGICCLOSE, 170 }; 171 int new_margin; 172 173 switch (cmd) { 174 case WDIOC_GETSUPPORT: 175 if (copy_to_user(argp, &ident, sizeof(ident))) 176 return -EFAULT; 177 return 0; 178 case WDIOC_GETSTATUS: 179 case WDIOC_GETBOOTSTATUS: 180 if (put_user(0, p)) 181 return -EFAULT; 182 return 0; 183 case WDIOC_KEEPALIVE: 184 scx200_wdt_ping(); 185 return 0; 186 case WDIOC_SETTIMEOUT: 187 if (get_user(new_margin, p)) 188 return -EFAULT; 189 if (new_margin < 1) 190 return -EINVAL; 191 margin = new_margin; 192 scx200_wdt_update_margin(); 193 scx200_wdt_ping(); 194 case WDIOC_GETTIMEOUT: 195 if (put_user(margin, p)) 196 return -EFAULT; 197 return 0; 198 default: 199 return -ENOTTY; 200 } 201} 202 203static const struct file_operations scx200_wdt_fops = { 204 .owner = THIS_MODULE, 205 .llseek = no_llseek, 206 .write = scx200_wdt_write, 207 .unlocked_ioctl = scx200_wdt_ioctl, 208 .open = scx200_wdt_open, 209 .release = scx200_wdt_release, 210}; 211 212static struct miscdevice scx200_wdt_miscdev = { 213 .minor = WATCHDOG_MINOR, 214 .name = "watchdog", 215 .fops = &scx200_wdt_fops, 216}; 217 218static int __init scx200_wdt_init(void) 219{ 220 int r; 221 222 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n"); 223 224 /* check that we have found the configuration block */ 225 if (!scx200_cb_present()) 226 return -ENODEV; 227 228 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET, 229 SCx200_WDT_SIZE, 230 "NatSemi SCx200 Watchdog")) { 231 printk(KERN_WARNING NAME ": watchdog I/O region busy\n"); 232 return -EBUSY; 233 } 234 235 scx200_wdt_update_margin(); 236 scx200_wdt_disable(); 237 238 r = register_reboot_notifier(&scx200_wdt_notifier); 239 if (r) { 240 printk(KERN_ERR NAME ": unable to register reboot notifier"); 241 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 242 SCx200_WDT_SIZE); 243 return r; 244 } 245 246 r = misc_register(&scx200_wdt_miscdev); 247 if (r) { 248 unregister_reboot_notifier(&scx200_wdt_notifier); 249 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 250 SCx200_WDT_SIZE); 251 return r; 252 } 253 254 return 0; 255} 256 257static void __exit scx200_wdt_cleanup(void) 258{ 259 misc_deregister(&scx200_wdt_miscdev); 260 unregister_reboot_notifier(&scx200_wdt_notifier); 261 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 262 SCx200_WDT_SIZE); 263} 264 265module_init(scx200_wdt_init); 266module_exit(scx200_wdt_cleanup); 267 268/* 269 Local variables: 270 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules" 271 c-basic-offset: 8 272 End: 273*/ 274