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@lxorguk.ukuu.org.uk>, 7 * All Rights Reserved. 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@lxorguk.ukuu.org.uk> 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 occurred 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 56 57 /* Includes */ 58 #include <linux/module.h> /* For module specific items */ 59 #include <linux/moduleparam.h> /* For new moduleparam's */ 60 #include <linux/types.h> /* For standard types (like size_t) */ 61 #include <linux/errno.h> /* For the -ENODEV/... values */ 62 #include <linux/kernel.h> /* For printk/panic/... */ 63 #include <linux/miscdevice.h> /* For MODULE_ALIAS_MISCDEV 64 (WATCHDOG_MINOR) */ 65 #include <linux/watchdog.h> /* For the watchdog specific items */ 66 #include <linux/fs.h> /* For file operations */ 67 #include <linux/ioport.h> /* For io-port access */ 68 #include <linux/platform_device.h> /* For platform_driver framework */ 69 #include <linux/init.h> /* For __init/__exit/... */ 70 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ 71 #include <linux/io.h> /* For inb/outb/... */ 72 73 /* Module information */ 74 #define DRV_NAME "acquirewdt" 75 #define WATCHDOG_NAME "Acquire WDT" 76 /* There is no way to see what the correct time-out period is */ 77 #define WATCHDOG_HEARTBEAT 0 78 79 /* internal variables */ 80 /* the watchdog platform device */ 81 static struct platform_device *acq_platform_device; 82 static unsigned long acq_is_open; 83 static char expect_close; 84 85 /* module parameters */ 86 /* You must set this - there is no sane way to probe for this board. */ 87 static int wdt_stop = 0x43; 88 module_param(wdt_stop, int, 0); 89 MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)"); 90 91 /* You must set this - there is no sane way to probe for this board. */ 92 static int wdt_start = 0x443; 93 module_param(wdt_start, int, 0); 94 MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)"); 95 96 static bool nowayout = WATCHDOG_NOWAYOUT; 97 module_param(nowayout, bool, 0); 98 MODULE_PARM_DESC(nowayout, 99 "Watchdog cannot be stopped once started (default=" 100 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 101 102 /* 103 * Watchdog Operations 104 */ 105 106 static void acq_keepalive(void) 107 { 108 /* Write a watchdog value */ 109 inb_p(wdt_start); 110 } 111 112 static void acq_stop(void) 113 { 114 /* Turn the card off */ 115 inb_p(wdt_stop); 116 } 117 118 /* 119 * /dev/watchdog handling 120 */ 121 122 static ssize_t acq_write(struct file *file, const char __user *buf, 123 size_t count, loff_t *ppos) 124 { 125 /* See if we got the magic character 'V' and reload the timer */ 126 if (count) { 127 if (!nowayout) { 128 size_t i; 129 /* note: just in case someone wrote the magic character 130 five months ago... */ 131 expect_close = 0; 132 /* scan to see whether or not we got the 133 magic character */ 134 for (i = 0; i != count; i++) { 135 char c; 136 if (get_user(c, buf + i)) 137 return -EFAULT; 138 if (c == 'V') 139 expect_close = 42; 140 } 141 } 142 /* Well, anyhow someone wrote to us, we should 143 return that favour */ 144 acq_keepalive(); 145 } 146 return count; 147 } 148 149 static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 150 { 151 int options, retval = -EINVAL; 152 void __user *argp = (void __user *)arg; 153 int __user *p = argp; 154 static const struct watchdog_info ident = { 155 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 156 .firmware_version = 1, 157 .identity = WATCHDOG_NAME, 158 }; 159 160 switch (cmd) { 161 case WDIOC_GETSUPPORT: 162 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 163 164 case WDIOC_GETSTATUS: 165 case WDIOC_GETBOOTSTATUS: 166 return put_user(0, p); 167 168 case WDIOC_SETOPTIONS: 169 { 170 if (get_user(options, p)) 171 return -EFAULT; 172 if (options & WDIOS_DISABLECARD) { 173 acq_stop(); 174 retval = 0; 175 } 176 if (options & WDIOS_ENABLECARD) { 177 acq_keepalive(); 178 retval = 0; 179 } 180 return retval; 181 } 182 case WDIOC_KEEPALIVE: 183 acq_keepalive(); 184 return 0; 185 186 case WDIOC_GETTIMEOUT: 187 return put_user(WATCHDOG_HEARTBEAT, p); 188 189 default: 190 return -ENOTTY; 191 } 192 } 193 194 static int acq_open(struct inode *inode, struct file *file) 195 { 196 if (test_and_set_bit(0, &acq_is_open)) 197 return -EBUSY; 198 199 if (nowayout) 200 __module_get(THIS_MODULE); 201 202 /* Activate */ 203 acq_keepalive(); 204 return nonseekable_open(inode, file); 205 } 206 207 static int acq_close(struct inode *inode, struct file *file) 208 { 209 if (expect_close == 42) { 210 acq_stop(); 211 } else { 212 pr_crit("Unexpected close, not stopping watchdog!\n"); 213 acq_keepalive(); 214 } 215 clear_bit(0, &acq_is_open); 216 expect_close = 0; 217 return 0; 218 } 219 220 /* 221 * Kernel Interfaces 222 */ 223 224 static const struct file_operations acq_fops = { 225 .owner = THIS_MODULE, 226 .llseek = no_llseek, 227 .write = acq_write, 228 .unlocked_ioctl = acq_ioctl, 229 .open = acq_open, 230 .release = acq_close, 231 }; 232 233 static struct miscdevice acq_miscdev = { 234 .minor = WATCHDOG_MINOR, 235 .name = "watchdog", 236 .fops = &acq_fops, 237 }; 238 239 /* 240 * Init & exit routines 241 */ 242 243 static int acq_probe(struct platform_device *dev) 244 { 245 int ret; 246 247 if (wdt_stop != wdt_start) { 248 if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) { 249 pr_err("I/O address 0x%04x already in use\n", wdt_stop); 250 ret = -EIO; 251 goto out; 252 } 253 } 254 255 if (!request_region(wdt_start, 1, WATCHDOG_NAME)) { 256 pr_err("I/O address 0x%04x already in use\n", wdt_start); 257 ret = -EIO; 258 goto unreg_stop; 259 } 260 ret = misc_register(&acq_miscdev); 261 if (ret != 0) { 262 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 263 WATCHDOG_MINOR, ret); 264 goto unreg_regions; 265 } 266 pr_info("initialized. (nowayout=%d)\n", nowayout); 267 268 return 0; 269 unreg_regions: 270 release_region(wdt_start, 1); 271 unreg_stop: 272 if (wdt_stop != wdt_start) 273 release_region(wdt_stop, 1); 274 out: 275 return ret; 276 } 277 278 static int __devexit acq_remove(struct platform_device *dev) 279 { 280 misc_deregister(&acq_miscdev); 281 release_region(wdt_start, 1); 282 if (wdt_stop != wdt_start) 283 release_region(wdt_stop, 1); 284 285 return 0; 286 } 287 288 static void acq_shutdown(struct platform_device *dev) 289 { 290 /* Turn the WDT off if we have a soft shutdown */ 291 acq_stop(); 292 } 293 294 static struct platform_driver acquirewdt_driver = { 295 .probe = acq_probe, 296 .remove = acq_remove, 297 .shutdown = acq_shutdown, 298 .driver = { 299 .owner = THIS_MODULE, 300 .name = DRV_NAME, 301 }, 302 }; 303 304 static int __init acq_init(void) 305 { 306 int err; 307 308 pr_info("WDT driver for Acquire single board computer initialising\n"); 309 310 err = platform_driver_register(&acquirewdt_driver); 311 if (err) 312 return err; 313 314 acq_platform_device = platform_device_register_simple(DRV_NAME, 315 -1, NULL, 0); 316 if (IS_ERR(acq_platform_device)) { 317 err = PTR_ERR(acq_platform_device); 318 goto unreg_platform_driver; 319 } 320 return 0; 321 322 unreg_platform_driver: 323 platform_driver_unregister(&acquirewdt_driver); 324 return err; 325 } 326 327 static void __exit acq_exit(void) 328 { 329 platform_device_unregister(acq_platform_device); 330 platform_driver_unregister(&acquirewdt_driver); 331 pr_info("Watchdog Module Unloaded\n"); 332 } 333 334 module_init(acq_init); 335 module_exit(acq_exit); 336 337 MODULE_AUTHOR("David Woodhouse"); 338 MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver"); 339 MODULE_LICENSE("GPL"); 340 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 341