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