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 31 #include <asm/uaccess.h> 32 #include <asm/io.h> 33 34 #define NAME "scx200_wdt" 35 36 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); 37 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver"); 38 MODULE_LICENSE("GPL"); 39 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 40 41 static int margin = 60; /* in seconds */ 42 module_param(margin, int, 0); 43 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 44 45 static int nowayout = WATCHDOG_NOWAYOUT; 46 module_param(nowayout, int, 0); 47 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 48 49 static u16 wdto_restart; 50 static struct semaphore open_semaphore; 51 static char expect_close; 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 60 static void scx200_wdt_ping(void) 61 { 62 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO); 63 } 64 65 static void scx200_wdt_update_margin(void) 66 { 67 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin); 68 wdto_restart = margin * W_SCALE; 69 } 70 71 static void scx200_wdt_enable(void) 72 { 73 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n", 74 wdto_restart); 75 76 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 77 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 78 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 79 80 scx200_wdt_ping(); 81 } 82 83 static void scx200_wdt_disable(void) 84 { 85 printk(KERN_DEBUG NAME ": disabling watchdog timer\n"); 86 87 outw(0, scx200_cb_base + SCx200_WDT_WDTO); 88 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS); 89 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG); 90 } 91 92 static int scx200_wdt_open(struct inode *inode, struct file *file) 93 { 94 /* only allow one at a time */ 95 if (down_trylock(&open_semaphore)) 96 return -EBUSY; 97 scx200_wdt_enable(); 98 99 return nonseekable_open(inode, file); 100 } 101 102 static int scx200_wdt_release(struct inode *inode, struct file *file) 103 { 104 if (expect_close != 42) { 105 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 106 } else if (!nowayout) { 107 scx200_wdt_disable(); 108 } 109 expect_close = 0; 110 up(&open_semaphore); 111 112 return 0; 113 } 114 115 static int scx200_wdt_notify_sys(struct notifier_block *this, 116 unsigned long code, void *unused) 117 { 118 if (code == SYS_HALT || code == SYS_POWER_OFF) 119 if (!nowayout) 120 scx200_wdt_disable(); 121 122 return NOTIFY_DONE; 123 } 124 125 static struct notifier_block scx200_wdt_notifier = 126 { 127 .notifier_call = scx200_wdt_notify_sys, 128 }; 129 130 static ssize_t scx200_wdt_write(struct file *file, const char __user *data, 131 size_t len, loff_t *ppos) 132 { 133 /* check for a magic close character */ 134 if (len) 135 { 136 size_t i; 137 138 scx200_wdt_ping(); 139 140 expect_close = 0; 141 for (i = 0; i < len; ++i) { 142 char c; 143 if (get_user(c, data+i)) 144 return -EFAULT; 145 if (c == 'V') 146 expect_close = 42; 147 } 148 149 return len; 150 } 151 152 return 0; 153 } 154 155 static int scx200_wdt_ioctl(struct inode *inode, struct file *file, 156 unsigned int cmd, unsigned long arg) 157 { 158 void __user *argp = (void __user *)arg; 159 int __user *p = argp; 160 static struct watchdog_info ident = { 161 .identity = "NatSemi SCx200 Watchdog", 162 .firmware_version = 1, 163 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING), 164 }; 165 int new_margin; 166 167 switch (cmd) { 168 default: 169 return -ENOTTY; 170 case WDIOC_GETSUPPORT: 171 if(copy_to_user(argp, &ident, sizeof(ident))) 172 return -EFAULT; 173 return 0; 174 case WDIOC_GETSTATUS: 175 case WDIOC_GETBOOTSTATUS: 176 if (put_user(0, p)) 177 return -EFAULT; 178 return 0; 179 case WDIOC_KEEPALIVE: 180 scx200_wdt_ping(); 181 return 0; 182 case WDIOC_SETTIMEOUT: 183 if (get_user(new_margin, p)) 184 return -EFAULT; 185 if (new_margin < 1) 186 return -EINVAL; 187 margin = new_margin; 188 scx200_wdt_update_margin(); 189 scx200_wdt_ping(); 190 case WDIOC_GETTIMEOUT: 191 if (put_user(margin, p)) 192 return -EFAULT; 193 return 0; 194 } 195 } 196 197 static const struct file_operations scx200_wdt_fops = { 198 .owner = THIS_MODULE, 199 .llseek = no_llseek, 200 .write = scx200_wdt_write, 201 .ioctl = scx200_wdt_ioctl, 202 .open = scx200_wdt_open, 203 .release = scx200_wdt_release, 204 }; 205 206 static struct miscdevice scx200_wdt_miscdev = { 207 .minor = WATCHDOG_MINOR, 208 .name = "watchdog", 209 .fops = &scx200_wdt_fops, 210 }; 211 212 static int __init scx200_wdt_init(void) 213 { 214 int r; 215 216 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n"); 217 218 /* check that we have found the configuration block */ 219 if (!scx200_cb_present()) 220 return -ENODEV; 221 222 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET, 223 SCx200_WDT_SIZE, 224 "NatSemi SCx200 Watchdog")) { 225 printk(KERN_WARNING NAME ": watchdog I/O region busy\n"); 226 return -EBUSY; 227 } 228 229 scx200_wdt_update_margin(); 230 scx200_wdt_disable(); 231 232 sema_init(&open_semaphore, 1); 233 234 r = register_reboot_notifier(&scx200_wdt_notifier); 235 if (r) { 236 printk(KERN_ERR NAME ": unable to register reboot notifier"); 237 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 238 SCx200_WDT_SIZE); 239 return r; 240 } 241 242 r = misc_register(&scx200_wdt_miscdev); 243 if (r) { 244 unregister_reboot_notifier(&scx200_wdt_notifier); 245 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 246 SCx200_WDT_SIZE); 247 return r; 248 } 249 250 return 0; 251 } 252 253 static void __exit scx200_wdt_cleanup(void) 254 { 255 misc_deregister(&scx200_wdt_miscdev); 256 unregister_reboot_notifier(&scx200_wdt_notifier); 257 release_region(scx200_cb_base + SCx200_WDT_OFFSET, 258 SCx200_WDT_SIZE); 259 } 260 261 module_init(scx200_wdt_init); 262 module_exit(scx200_wdt_cleanup); 263 264 /* 265 Local variables: 266 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules" 267 c-basic-offset: 8 268 End: 269 */ 270