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" on success 20 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read 21 * fix possible wdt_is_open race 22 * add CONFIG_WATCHDOG_NOWAYOUT support 23 * remove lock_kernel/unlock_kernel pairs 24 * added KERN_* to printk's 25 * got rid of extraneous comments 26 * changed watchdog_info to correctly reflect what the driver offers 27 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT, 28 * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls 29 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces 30 * use module_param 31 * made timeout (the emulated heartbeat) a module_param 32 * made the keepalive ping an internal subroutine 33 * made wdt_stop and wdt_start module params 34 * added extra printk's for startup problems 35 * added MODULE_AUTHOR and MODULE_DESCRIPTION info 36 * 37 * 38 * This WDT driver is different from the other Linux WDT 39 * drivers in the following ways: 40 * *) The driver will ping the watchdog by itself, because this 41 * particular WDT has a very short timeout (one second) and it 42 * would be insane to count on any userspace daemon always 43 * getting scheduled within that time frame. 44 * 45 */ 46 47#include <linux/module.h> 48#include <linux/moduleparam.h> 49#include <linux/types.h> 50#include <linux/timer.h> 51#include <linux/jiffies.h> 52#include <linux/miscdevice.h> 53#include <linux/watchdog.h> 54#include <linux/fs.h> 55#include <linux/ioport.h> 56#include <linux/notifier.h> 57#include <linux/reboot.h> 58#include <linux/init.h> 59 60#include <asm/io.h> 61#include <asm/uaccess.h> 62#include <asm/system.h> 63 64#define OUR_NAME "sbc60xxwdt" 65#define PFX OUR_NAME ": " 66 67/* 68 * You must set these - The driver cannot probe for the settings 69 */ 70 71static int wdt_stop = 0x45; 72module_param(wdt_stop, int, 0); 73MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); 74 75static int wdt_start = 0x443; 76module_param(wdt_start, int, 0); 77MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); 78 79/* 80 * The 60xx board can use watchdog timeout values from one second 81 * to several minutes. The default is one second, so if we reset 82 * the watchdog every ~250ms we should be safe. 83 */ 84 85#define WDT_INTERVAL (HZ/4+1) 86 87/* 88 * We must not require too good response from the userspace daemon. 89 * Here we require the userspace daemon to send us a heartbeat 90 * char to /dev/watchdog every 30 seconds. 91 * If the daemon pulses us every 25 seconds, we can still afford 92 * a 5 second scheduling delay on the (high priority) daemon. That 93 * should be sufficient for a box under any load. 94 */ 95 96#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 97static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ 98module_param(timeout, int, 0); 99MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 100 101static int nowayout = WATCHDOG_NOWAYOUT; 102module_param(nowayout, int, 0); 103MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 104 105static void wdt_timer_ping(unsigned long); 106static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); 107static unsigned long next_heartbeat; 108static unsigned long wdt_is_open; 109static char wdt_expect_close; 110 111/* 112 * Whack the dog 113 */ 114 115static void wdt_timer_ping(unsigned long data) 116{ 117 /* If we got a heartbeat pulse within the WDT_US_INTERVAL 118 * we agree to ping the WDT 119 */ 120 if(time_before(jiffies, next_heartbeat)) 121 { 122 /* Ping the WDT by reading from wdt_start */ 123 inb_p(wdt_start); 124 /* Re-set the timer interval */ 125 mod_timer(&timer, jiffies + WDT_INTERVAL); 126 } else { 127 printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n"); 128 } 129} 130 131/* 132 * Utility routines 133 */ 134 135static void wdt_startup(void) 136{ 137 next_heartbeat = jiffies + (timeout * HZ); 138 139 /* Start the timer */ 140 mod_timer(&timer, jiffies + WDT_INTERVAL); 141 printk(KERN_INFO PFX "Watchdog timer is now enabled.\n"); 142} 143 144static void wdt_turnoff(void) 145{ 146 /* Stop the timer */ 147 del_timer(&timer); 148 inb_p(wdt_stop); 149 printk(KERN_INFO PFX "Watchdog timer is now disabled...\n"); 150} 151 152static void wdt_keepalive(void) 153{ 154 /* user land ping */ 155 next_heartbeat = jiffies + (timeout * HZ); 156} 157 158/* 159 * /dev/watchdog handling 160 */ 161 162static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos) 163{ 164 /* See if we got the magic character 'V' and reload the timer */ 165 if(count) 166 { 167 if (!nowayout) 168 { 169 size_t ofs; 170 171 /* note: just in case someone wrote the magic character 172 * five months ago... */ 173 wdt_expect_close = 0; 174 175 /* scan to see whether or not we got the magic character */ 176 for(ofs = 0; ofs != count; ofs++) 177 { 178 char c; 179 if(get_user(c, buf+ofs)) 180 return -EFAULT; 181 if(c == 'V') 182 wdt_expect_close = 42; 183 } 184 } 185 186 /* Well, anyhow someone wrote to us, we should return that favour */ 187 wdt_keepalive(); 188 } 189 return count; 190} 191 192static int fop_open(struct inode * inode, struct file * file) 193{ 194 nonseekable_open(inode, file); 195 196 /* Just in case we're already talking to someone... */ 197 if(test_and_set_bit(0, &wdt_is_open)) 198 return -EBUSY; 199 200 if (nowayout) 201 __module_get(THIS_MODULE); 202 203 /* Good, fire up the show */ 204 wdt_startup(); 205 return 0; 206} 207 208static int fop_close(struct inode * inode, struct file * file) 209{ 210 if(wdt_expect_close == 42) 211 wdt_turnoff(); 212 else { 213 del_timer(&timer); 214 printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n"); 215 } 216 clear_bit(0, &wdt_is_open); 217 wdt_expect_close = 0; 218 return 0; 219} 220 221static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 222 unsigned long arg) 223{ 224 void __user *argp = (void __user *)arg; 225 int __user *p = argp; 226 static struct watchdog_info ident= 227 { 228 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, 229 .firmware_version = 1, 230 .identity = "SBC60xx", 231 }; 232 233 switch(cmd) 234 { 235 default: 236 return -ENOTTY; 237 case WDIOC_GETSUPPORT: 238 return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0; 239 case WDIOC_GETSTATUS: 240 case WDIOC_GETBOOTSTATUS: 241 return put_user(0, p); 242 case WDIOC_KEEPALIVE: 243 wdt_keepalive(); 244 return 0; 245 case WDIOC_SETOPTIONS: 246 { 247 int new_options, retval = -EINVAL; 248 249 if(get_user(new_options, p)) 250 return -EFAULT; 251 252 if(new_options & WDIOS_DISABLECARD) { 253 wdt_turnoff(); 254 retval = 0; 255 } 256 257 if(new_options & WDIOS_ENABLECARD) { 258 wdt_startup(); 259 retval = 0; 260 } 261 262 return retval; 263 } 264 case WDIOC_SETTIMEOUT: 265 { 266 int new_timeout; 267 268 if(get_user(new_timeout, p)) 269 return -EFAULT; 270 271 if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */ 272 return -EINVAL; 273 274 timeout = new_timeout; 275 wdt_keepalive(); 276 /* Fall through */ 277 } 278 case WDIOC_GETTIMEOUT: 279 return put_user(timeout, p); 280 } 281} 282 283static const struct file_operations wdt_fops = { 284 .owner = THIS_MODULE, 285 .llseek = no_llseek, 286 .write = fop_write, 287 .open = fop_open, 288 .release = fop_close, 289 .ioctl = fop_ioctl, 290}; 291 292static struct miscdevice wdt_miscdev = { 293 .minor = WATCHDOG_MINOR, 294 .name = "watchdog", 295 .fops = &wdt_fops, 296}; 297 298/* 299 * Notifier for system down 300 */ 301 302static int wdt_notify_sys(struct notifier_block *this, unsigned long code, 303 void *unused) 304{ 305 if(code==SYS_DOWN || code==SYS_HALT) 306 wdt_turnoff(); 307 return NOTIFY_DONE; 308} 309 310/* 311 * The WDT needs to learn about soft shutdowns in order to 312 * turn the timebomb registers off. 313 */ 314 315static struct notifier_block wdt_notifier= 316{ 317 .notifier_call = wdt_notify_sys, 318}; 319 320static void __exit sbc60xxwdt_unload(void) 321{ 322 wdt_turnoff(); 323 324 /* Deregister */ 325 misc_deregister(&wdt_miscdev); 326 327 unregister_reboot_notifier(&wdt_notifier); 328 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 329 release_region(wdt_stop,1); 330 release_region(wdt_start,1); 331} 332 333static int __init sbc60xxwdt_init(void) 334{ 335 int rc = -EBUSY; 336 337 if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */ 338 { 339 timeout = WATCHDOG_TIMEOUT; 340 printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n", 341 timeout); 342 } 343 344 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) 345 { 346 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n", 347 wdt_start); 348 rc = -EIO; 349 goto err_out; 350 } 351 352 /* We cannot reserve 0x45 - the kernel already has! */ 353 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 354 { 355 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) 356 { 357 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n", 358 wdt_stop); 359 rc = -EIO; 360 goto err_out_region1; 361 } 362 } 363 364 rc = misc_register(&wdt_miscdev); 365 if (rc) 366 { 367 printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", 368 wdt_miscdev.minor, rc); 369 goto err_out_region2; 370 } 371 372 rc = register_reboot_notifier(&wdt_notifier); 373 if (rc) 374 { 375 printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", 376 rc); 377 goto err_out_miscdev; 378 } 379 380 printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", 381 timeout, nowayout); 382 383 return 0; 384 385err_out_miscdev: 386 misc_deregister(&wdt_miscdev); 387err_out_region2: 388 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 389 release_region(wdt_stop,1); 390err_out_region1: 391 release_region(wdt_start,1); 392err_out: 393 return rc; 394} 395 396module_init(sbc60xxwdt_init); 397module_exit(sbc60xxwdt_unload); 398 399MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); 400MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); 401MODULE_LICENSE("GPL"); 402MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 403