1 /* 2 * Acquire Single Board Computer Watchdog Timer driver 3 * 4 * Based on wdt.c. Original copyright messages: 5 * 6 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. 7 * http://www.redhat.com 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 * 14 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide 15 * warranty for any of this software. This material is provided 16 * "AS-IS" and at no charge. 17 * 18 * (c) Copyright 1995 Alan Cox <alan@redhat.com> 19 * 20 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> 21 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT 22 * Can't add timeout - driver doesn't allow changing value 23 */ 24 25 /* 26 * Theory of Operation: 27 * The Watch-Dog Timer is provided to ensure that standalone 28 * Systems can always recover from catastrophic conditions that 29 * caused the CPU to crash. This condition may have occured by 30 * external EMI or a software bug. When the CPU stops working 31 * correctly, hardware on the board will either perform a hardware 32 * reset (cold boot) or a non-maskable interrupt (NMI) to bring the 33 * system back to a known state. 34 * 35 * The Watch-Dog Timer is controlled by two I/O Ports. 36 * 443 hex - Read - Enable or refresh the Watch-Dog Timer 37 * 043 hex - Read - Disable the Watch-Dog Timer 38 * 39 * To enable the Watch-Dog Timer, a read from I/O port 443h must 40 * be performed. This will enable and activate the countdown timer 41 * which will eventually time out and either reset the CPU or cause 42 * an NMI depending on the setting of a jumper. To ensure that this 43 * reset condition does not occur, the Watch-Dog Timer must be 44 * periodically refreshed by reading the same I/O port 443h. 45 * The Watch-Dog Timer is disabled by reading I/O port 043h. 46 * 47 * The Watch-Dog Timer Time-Out Period is set via jumpers. 48 * It can be 1, 2, 10, 20, 110 or 220 seconds. 49 */ 50 51 /* 52 * Includes, defines, variables, module parameters, ... 53 */ 54 55 /* Includes */ 56 #include <linux/module.h> /* For module specific items */ 57 #include <linux/moduleparam.h> /* For new moduleparam's */ 58 #include <linux/types.h> /* For standard types (like size_t) */ 59 #include <linux/errno.h> /* For the -ENODEV/... values */ 60 #include <linux/kernel.h> /* For printk/panic/... */ 61 #include <linux/miscdevice.h> /* For MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR) */ 62 #include <linux/watchdog.h> /* For the watchdog specific items */ 63 #include <linux/fs.h> /* For file operations */ 64 #include <linux/ioport.h> /* For io-port access */ 65 #include <linux/platform_device.h> /* For platform_driver framework */ 66 #include <linux/init.h> /* For __init/__exit/... */ 67 68 #include <asm/uaccess.h> /* For copy_to_user/put_user/... */ 69 #include <asm/io.h> /* For inb/outb/... */ 70 71 /* Module information */ 72 #define DRV_NAME "acquirewdt" 73 #define PFX DRV_NAME ": " 74 #define WATCHDOG_NAME "Acquire WDT" 75 #define WATCHDOG_HEARTBEAT 0 /* There is no way to see what the correct time-out period is */ 76 77 /* internal variables */ 78 static struct platform_device *acq_platform_device; /* the watchdog platform device */ 79 static unsigned long acq_is_open; 80 static char expect_close; 81 82 /* module parameters */ 83 static int wdt_stop = 0x43; /* You must set this - there is no sane way to probe for this board. */ 84 module_param(wdt_stop, int, 0); 85 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)"); 86 87 static int wdt_start = 0x443; /* You must set this - there is no sane way to probe for this board. */ 88 module_param(wdt_start, int, 0); 89 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)"); 90 91 static int nowayout = WATCHDOG_NOWAYOUT; 92 module_param(nowayout, int, 0); 93 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 94 95 /* 96 * Watchdog Operations 97 */ 98 99 static void acq_keepalive(void) 100 { 101 /* Write a watchdog value */ 102 inb_p(wdt_start); 103 } 104 105 static void acq_stop(void) 106 { 107 /* Turn the card off */ 108 inb_p(wdt_stop); 109 } 110 111 /* 112 * /dev/watchdog handling 113 */ 114 115 static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 116 { 117 /* See if we got the magic character 'V' and reload the timer */ 118 if(count) { 119 if (!nowayout) { 120 size_t i; 121 122 /* note: just in case someone wrote the magic character 123 * five months ago... */ 124 expect_close = 0; 125 126 /* scan to see whether or not we got the magic character */ 127 for (i = 0; i != count; i++) { 128 char c; 129 if (get_user(c, buf + i)) 130 return -EFAULT; 131 if (c == 'V') 132 expect_close = 42; 133 } 134 } 135 136 /* Well, anyhow someone wrote to us, we should return that favour */ 137 acq_keepalive(); 138 } 139 return count; 140 } 141 142 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 143 unsigned long arg) 144 { 145 int options, retval = -EINVAL; 146 void __user *argp = (void __user *)arg; 147 int __user *p = argp; 148 static struct watchdog_info ident = 149 { 150 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 151 .firmware_version = 1, 152 .identity = WATCHDOG_NAME, 153 }; 154 155 switch(cmd) 156 { 157 case WDIOC_GETSUPPORT: 158 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 159 160 case WDIOC_GETSTATUS: 161 case WDIOC_GETBOOTSTATUS: 162 return put_user(0, p); 163 164 case WDIOC_KEEPALIVE: 165 acq_keepalive(); 166 return 0; 167 168 case WDIOC_GETTIMEOUT: 169 return put_user(WATCHDOG_HEARTBEAT, p); 170 171 case WDIOC_SETOPTIONS: 172 { 173 if (get_user(options, p)) 174 return -EFAULT; 175 176 if (options & WDIOS_DISABLECARD) 177 { 178 acq_stop(); 179 retval = 0; 180 } 181 182 if (options & WDIOS_ENABLECARD) 183 { 184 acq_keepalive(); 185 retval = 0; 186 } 187 188 return retval; 189 } 190 191 default: 192 return -ENOTTY; 193 } 194 } 195 196 static int acq_open(struct inode *inode, struct file *file) 197 { 198 if (test_and_set_bit(0, &acq_is_open)) 199 return -EBUSY; 200 201 if (nowayout) 202 __module_get(THIS_MODULE); 203 204 /* Activate */ 205 acq_keepalive(); 206 return nonseekable_open(inode, file); 207 } 208 209 static int acq_close(struct inode *inode, struct file *file) 210 { 211 if (expect_close == 42) { 212 acq_stop(); 213 } else { 214 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); 215 acq_keepalive(); 216 } 217 clear_bit(0, &acq_is_open); 218 expect_close = 0; 219 return 0; 220 } 221 222 /* 223 * Kernel Interfaces 224 */ 225 226 static const struct file_operations acq_fops = { 227 .owner = THIS_MODULE, 228 .llseek = no_llseek, 229 .write = acq_write, 230 .ioctl = acq_ioctl, 231 .open = acq_open, 232 .release = acq_close, 233 }; 234 235 static struct miscdevice acq_miscdev = { 236 .minor = WATCHDOG_MINOR, 237 .name = "watchdog", 238 .fops = &acq_fops, 239 }; 240 241 /* 242 * Init & exit routines 243 */ 244 245 static int __devinit acq_probe(struct platform_device *dev) 246 { 247 int ret; 248 249 if (wdt_stop != wdt_start) { 250 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) { 251 printk (KERN_ERR PFX "I/O address 0x%04x already in use\n", 252 wdt_stop); 253 ret = -EIO; 254 goto out; 255 } 256 } 257 258 if (!request_region(wdt_start, 1, WATCHDOG_NAME)) { 259 printk (KERN_ERR PFX "I/O address 0x%04x already in use\n", 260 wdt_start); 261 ret = -EIO; 262 goto unreg_stop; 263 } 264 265 ret = misc_register(&acq_miscdev); 266 if (ret != 0) { 267 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", 268 WATCHDOG_MINOR, ret); 269 goto unreg_regions; 270 } 271 272 printk (KERN_INFO PFX "initialized. (nowayout=%d)\n", 273 nowayout); 274 275 return 0; 276 277 unreg_regions: 278 release_region(wdt_start, 1); 279 unreg_stop: 280 if (wdt_stop != wdt_start) 281 release_region(wdt_stop, 1); 282 out: 283 return ret; 284 } 285 286 static int __devexit acq_remove(struct platform_device *dev) 287 { 288 misc_deregister(&acq_miscdev); 289 release_region(wdt_start,1); 290 if(wdt_stop != wdt_start) 291 release_region(wdt_stop,1); 292 293 return 0; 294 } 295 296 static void acq_shutdown(struct platform_device *dev) 297 { 298 /* Turn the WDT off if we have a soft shutdown */ 299 acq_stop(); 300 } 301 302 static struct platform_driver acquirewdt_driver = { 303 .probe = acq_probe, 304 .remove = __devexit_p(acq_remove), 305 .shutdown = acq_shutdown, 306 .driver = { 307 .owner = THIS_MODULE, 308 .name = DRV_NAME, 309 }, 310 }; 311 312 static int __init acq_init(void) 313 { 314 int err; 315 316 printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n"); 317 318 err = platform_driver_register(&acquirewdt_driver); 319 if (err) 320 return err; 321 322 acq_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0); 323 if (IS_ERR(acq_platform_device)) { 324 err = PTR_ERR(acq_platform_device); 325 goto unreg_platform_driver; 326 } 327 328 return 0; 329 330 unreg_platform_driver: 331 platform_driver_unregister(&acquirewdt_driver); 332 return err; 333 } 334 335 static void __exit acq_exit(void) 336 { 337 platform_device_unregister(acq_platform_device); 338 platform_driver_unregister(&acquirewdt_driver); 339 printk(KERN_INFO PFX "Watchdog Module Unloaded.\n"); 340 } 341 342 module_init(acq_init); 343 module_exit(acq_exit); 344 345 MODULE_AUTHOR("David Woodhouse"); 346 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver"); 347 MODULE_LICENSE("GPL"); 348 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 349