1 /* 2 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x 3 * 4 * Based on acquirewdt.c by Alan Cox. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 * 11 * The author does NOT admit liability nor provide warranty for 12 * any of this software. This material is provided "AS-IS" in 13 * the hope that it may be useful for others. 14 * 15 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> 16 * 17 * 12/4 - 2000 [Initial revision] 18 * 25/4 - 2000 Added /dev/watchdog support 19 * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" 20 * on success 21 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read 22 * fix possible wdt_is_open race 23 * add CONFIG_WATCHDOG_NOWAYOUT support 24 * remove lock_kernel/unlock_kernel pairs 25 * added KERN_* to printk's 26 * got rid of extraneous comments 27 * changed watchdog_info to correctly reflect what 28 * the driver offers 29 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, 30 * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and 31 * WDIOC_SETOPTIONS ioctls 32 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces 33 * use module_param 34 * made timeout (the emulated heartbeat) a 35 * module_param 36 * made the keepalive ping an internal subroutine 37 * made wdt_stop and wdt_start module params 38 * added extra printk's for startup problems 39 * added MODULE_AUTHOR and MODULE_DESCRIPTION info 40 * 41 * 42 * This WDT driver is different from the other Linux WDT 43 * drivers in the following ways: 44 * *) The driver will ping the watchdog by itself, because this 45 * particular WDT has a very short timeout (one second) and it 46 * would be insane to count on any userspace daemon always 47 * getting scheduled within that time frame. 48 * 49 */ 50 51 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 52 53 #include <linux/module.h> 54 #include <linux/moduleparam.h> 55 #include <linux/types.h> 56 #include <linux/timer.h> 57 #include <linux/jiffies.h> 58 #include <linux/miscdevice.h> 59 #include <linux/watchdog.h> 60 #include <linux/fs.h> 61 #include <linux/ioport.h> 62 #include <linux/notifier.h> 63 #include <linux/reboot.h> 64 #include <linux/init.h> 65 #include <linux/io.h> 66 #include <linux/uaccess.h> 67 68 69 #define OUR_NAME "sbc60xxwdt" 70 #define PFX OUR_NAME ": " 71 72 /* 73 * You must set these - The driver cannot probe for the settings 74 */ 75 76 static int wdt_stop = 0x45; 77 module_param(wdt_stop, int, 0); 78 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); 79 80 static int wdt_start = 0x443; 81 module_param(wdt_start, int, 0); 82 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); 83 84 /* 85 * The 60xx board can use watchdog timeout values from one second 86 * to several minutes. The default is one second, so if we reset 87 * the watchdog every ~250ms we should be safe. 88 */ 89 90 #define WDT_INTERVAL (HZ/4+1) 91 92 /* 93 * We must not require too good response from the userspace daemon. 94 * Here we require the userspace daemon to send us a heartbeat 95 * char to /dev/watchdog every 30 seconds. 96 * If the daemon pulses us every 25 seconds, we can still afford 97 * a 5 second scheduling delay on the (high priority) daemon. That 98 * should be sufficient for a box under any load. 99 */ 100 101 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 102 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to 103 get seconds to wait for a ping */ 104 module_param(timeout, int, 0); 105 MODULE_PARM_DESC(timeout, 106 "Watchdog timeout in seconds. (1<=timeout<=3600, default=" 107 __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 108 109 static bool nowayout = WATCHDOG_NOWAYOUT; 110 module_param(nowayout, bool, 0); 111 MODULE_PARM_DESC(nowayout, 112 "Watchdog cannot be stopped once started (default=" 113 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 114 115 static void wdt_timer_ping(unsigned long); 116 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); 117 static unsigned long next_heartbeat; 118 static unsigned long wdt_is_open; 119 static char wdt_expect_close; 120 121 /* 122 * Whack the dog 123 */ 124 125 static void wdt_timer_ping(unsigned long data) 126 { 127 /* If we got a heartbeat pulse within the WDT_US_INTERVAL 128 * we agree to ping the WDT 129 */ 130 if (time_before(jiffies, next_heartbeat)) { 131 /* Ping the WDT by reading from wdt_start */ 132 inb_p(wdt_start); 133 /* Re-set the timer interval */ 134 mod_timer(&timer, jiffies + WDT_INTERVAL); 135 } else 136 pr_warn("Heartbeat lost! Will not ping the watchdog\n"); 137 } 138 139 /* 140 * Utility routines 141 */ 142 143 static void wdt_startup(void) 144 { 145 next_heartbeat = jiffies + (timeout * HZ); 146 147 /* Start the timer */ 148 mod_timer(&timer, jiffies + WDT_INTERVAL); 149 pr_info("Watchdog timer is now enabled\n"); 150 } 151 152 static void wdt_turnoff(void) 153 { 154 /* Stop the timer */ 155 del_timer(&timer); 156 inb_p(wdt_stop); 157 pr_info("Watchdog timer is now disabled...\n"); 158 } 159 160 static void wdt_keepalive(void) 161 { 162 /* user land ping */ 163 next_heartbeat = jiffies + (timeout * HZ); 164 } 165 166 /* 167 * /dev/watchdog handling 168 */ 169 170 static ssize_t fop_write(struct file *file, const char __user *buf, 171 size_t count, loff_t *ppos) 172 { 173 /* See if we got the magic character 'V' and reload the timer */ 174 if (count) { 175 if (!nowayout) { 176 size_t ofs; 177 178 /* note: just in case someone wrote the 179 magic character five months ago... */ 180 wdt_expect_close = 0; 181 182 /* scan to see whether or not we got the 183 magic character */ 184 for (ofs = 0; ofs != count; ofs++) { 185 char c; 186 if (get_user(c, buf + ofs)) 187 return -EFAULT; 188 if (c == 'V') 189 wdt_expect_close = 42; 190 } 191 } 192 193 /* Well, anyhow someone wrote to us, we should 194 return that favour */ 195 wdt_keepalive(); 196 } 197 return count; 198 } 199 200 static int fop_open(struct inode *inode, struct file *file) 201 { 202 /* Just in case we're already talking to someone... */ 203 if (test_and_set_bit(0, &wdt_is_open)) 204 return -EBUSY; 205 206 if (nowayout) 207 __module_get(THIS_MODULE); 208 209 /* Good, fire up the show */ 210 wdt_startup(); 211 return nonseekable_open(inode, file); 212 } 213 214 static int fop_close(struct inode *inode, struct file *file) 215 { 216 if (wdt_expect_close == 42) 217 wdt_turnoff(); 218 else { 219 del_timer(&timer); 220 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n"); 221 } 222 clear_bit(0, &wdt_is_open); 223 wdt_expect_close = 0; 224 return 0; 225 } 226 227 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 228 { 229 void __user *argp = (void __user *)arg; 230 int __user *p = argp; 231 static const struct watchdog_info ident = { 232 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | 233 WDIOF_MAGICCLOSE, 234 .firmware_version = 1, 235 .identity = "SBC60xx", 236 }; 237 238 switch (cmd) { 239 case WDIOC_GETSUPPORT: 240 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 241 case WDIOC_GETSTATUS: 242 case WDIOC_GETBOOTSTATUS: 243 return put_user(0, p); 244 case WDIOC_SETOPTIONS: 245 { 246 int new_options, retval = -EINVAL; 247 if (get_user(new_options, p)) 248 return -EFAULT; 249 if (new_options & WDIOS_DISABLECARD) { 250 wdt_turnoff(); 251 retval = 0; 252 } 253 if (new_options & WDIOS_ENABLECARD) { 254 wdt_startup(); 255 retval = 0; 256 } 257 return retval; 258 } 259 case WDIOC_KEEPALIVE: 260 wdt_keepalive(); 261 return 0; 262 case WDIOC_SETTIMEOUT: 263 { 264 int new_timeout; 265 if (get_user(new_timeout, p)) 266 return -EFAULT; 267 /* arbitrary upper limit */ 268 if (new_timeout < 1 || new_timeout > 3600) 269 return -EINVAL; 270 271 timeout = new_timeout; 272 wdt_keepalive(); 273 /* Fall through */ 274 } 275 case WDIOC_GETTIMEOUT: 276 return put_user(timeout, p); 277 default: 278 return -ENOTTY; 279 } 280 } 281 282 static const struct file_operations wdt_fops = { 283 .owner = THIS_MODULE, 284 .llseek = no_llseek, 285 .write = fop_write, 286 .open = fop_open, 287 .release = fop_close, 288 .unlocked_ioctl = fop_ioctl, 289 }; 290 291 static struct miscdevice wdt_miscdev = { 292 .minor = WATCHDOG_MINOR, 293 .name = "watchdog", 294 .fops = &wdt_fops, 295 }; 296 297 /* 298 * Notifier for system down 299 */ 300 301 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, 302 void *unused) 303 { 304 if (code == SYS_DOWN || code == SYS_HALT) 305 wdt_turnoff(); 306 return NOTIFY_DONE; 307 } 308 309 /* 310 * The WDT needs to learn about soft shutdowns in order to 311 * turn the timebomb registers off. 312 */ 313 314 static struct notifier_block wdt_notifier = { 315 .notifier_call = wdt_notify_sys, 316 }; 317 318 static void __exit sbc60xxwdt_unload(void) 319 { 320 wdt_turnoff(); 321 322 /* Deregister */ 323 misc_deregister(&wdt_miscdev); 324 325 unregister_reboot_notifier(&wdt_notifier); 326 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 327 release_region(wdt_stop, 1); 328 release_region(wdt_start, 1); 329 } 330 331 static int __init sbc60xxwdt_init(void) 332 { 333 int rc = -EBUSY; 334 335 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ 336 timeout = WATCHDOG_TIMEOUT; 337 pr_info("timeout value must be 1 <= x <= 3600, using %d\n", 338 timeout); 339 } 340 341 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) { 342 pr_err("I/O address 0x%04x already in use\n", wdt_start); 343 rc = -EIO; 344 goto err_out; 345 } 346 347 /* We cannot reserve 0x45 - the kernel already has! */ 348 if (wdt_stop != 0x45 && wdt_stop != wdt_start) { 349 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) { 350 pr_err("I/O address 0x%04x already in use\n", wdt_stop); 351 rc = -EIO; 352 goto err_out_region1; 353 } 354 } 355 356 rc = register_reboot_notifier(&wdt_notifier); 357 if (rc) { 358 pr_err("cannot register reboot notifier (err=%d)\n", rc); 359 goto err_out_region2; 360 } 361 362 rc = misc_register(&wdt_miscdev); 363 if (rc) { 364 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 365 wdt_miscdev.minor, rc); 366 goto err_out_reboot; 367 } 368 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", 369 timeout, nowayout); 370 371 return 0; 372 373 err_out_reboot: 374 unregister_reboot_notifier(&wdt_notifier); 375 err_out_region2: 376 if (wdt_stop != 0x45 && wdt_stop != wdt_start) 377 release_region(wdt_stop, 1); 378 err_out_region1: 379 release_region(wdt_start, 1); 380 err_out: 381 return rc; 382 } 383 384 module_init(sbc60xxwdt_init); 385 module_exit(sbc60xxwdt_unload); 386 387 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); 388 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); 389 MODULE_LICENSE("GPL"); 390