1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x 4 * 5 * Based on acquirewdt.c by Alan Cox. 6 * 7 * The author does NOT admit liability nor provide warranty for 8 * any of this software. This material is provided "AS-IS" in 9 * the hope that it may be useful for others. 10 * 11 * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> 12 * 13 * 12/4 - 2000 [Initial revision] 14 * 25/4 - 2000 Added /dev/watchdog support 15 * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" 16 * on success 17 * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read 18 * fix possible wdt_is_open race 19 * add CONFIG_WATCHDOG_NOWAYOUT support 20 * remove lock_kernel/unlock_kernel pairs 21 * added KERN_* to printk's 22 * got rid of extraneous comments 23 * changed watchdog_info to correctly reflect what 24 * the driver offers 25 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, 26 * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and 27 * WDIOC_SETOPTIONS ioctls 28 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces 29 * use module_param 30 * made timeout (the emulated heartbeat) a 31 * 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 * This WDT driver is different from the other Linux WDT 38 * drivers in the following ways: 39 * *) The driver will ping the watchdog by itself, because this 40 * particular WDT has a very short timeout (one second) and it 41 * would be insane to count on any userspace daemon always 42 * getting scheduled within that time frame. 43 */ 44 45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 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 #include <linux/io.h> 60 #include <linux/uaccess.h> 61 62 63 #define OUR_NAME "sbc60xxwdt" 64 #define PFX OUR_NAME ": " 65 66 /* 67 * You must set these - The driver cannot probe for the settings 68 */ 69 70 static int wdt_stop = 0x45; 71 module_param(wdt_stop, int, 0); 72 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); 73 74 static int wdt_start = 0x443; 75 module_param(wdt_start, int, 0); 76 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); 77 78 /* 79 * The 60xx board can use watchdog timeout values from one second 80 * to several minutes. The default is one second, so if we reset 81 * the watchdog every ~250ms we should be safe. 82 */ 83 84 #define WDT_INTERVAL (HZ/4+1) 85 86 /* 87 * We must not require too good response from the userspace daemon. 88 * Here we require the userspace daemon to send us a heartbeat 89 * char to /dev/watchdog every 30 seconds. 90 * If the daemon pulses us every 25 seconds, we can still afford 91 * a 5 second scheduling delay on the (high priority) daemon. That 92 * should be sufficient for a box under any load. 93 */ 94 95 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ 96 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to 97 get seconds to wait for a ping */ 98 module_param(timeout, int, 0); 99 MODULE_PARM_DESC(timeout, 100 "Watchdog timeout in seconds. (1<=timeout<=3600, default=" 101 __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); 102 103 static bool nowayout = WATCHDOG_NOWAYOUT; 104 module_param(nowayout, bool, 0); 105 MODULE_PARM_DESC(nowayout, 106 "Watchdog cannot be stopped once started (default=" 107 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 108 109 static void wdt_timer_ping(struct timer_list *); 110 static DEFINE_TIMER(timer, wdt_timer_ping); 111 static unsigned long next_heartbeat; 112 static unsigned long wdt_is_open; 113 static char wdt_expect_close; 114 115 /* 116 * Whack the dog 117 */ 118 119 static void wdt_timer_ping(struct timer_list *unused) 120 { 121 /* If we got a heartbeat pulse within the WDT_US_INTERVAL 122 * we agree to ping the WDT 123 */ 124 if (time_before(jiffies, next_heartbeat)) { 125 /* Ping the WDT by reading from wdt_start */ 126 inb_p(wdt_start); 127 /* Re-set the timer interval */ 128 mod_timer(&timer, jiffies + WDT_INTERVAL); 129 } else 130 pr_warn("Heartbeat lost! Will not ping the watchdog\n"); 131 } 132 133 /* 134 * Utility routines 135 */ 136 137 static void wdt_startup(void) 138 { 139 next_heartbeat = jiffies + (timeout * HZ); 140 141 /* Start the timer */ 142 mod_timer(&timer, jiffies + WDT_INTERVAL); 143 pr_info("Watchdog timer is now enabled\n"); 144 } 145 146 static void wdt_turnoff(void) 147 { 148 /* Stop the timer */ 149 del_timer(&timer); 150 inb_p(wdt_stop); 151 pr_info("Watchdog timer is now disabled...\n"); 152 } 153 154 static void wdt_keepalive(void) 155 { 156 /* user land ping */ 157 next_heartbeat = jiffies + (timeout * HZ); 158 } 159 160 /* 161 * /dev/watchdog handling 162 */ 163 164 static ssize_t fop_write(struct file *file, const char __user *buf, 165 size_t count, loff_t *ppos) 166 { 167 /* See if we got the magic character 'V' and reload the timer */ 168 if (count) { 169 if (!nowayout) { 170 size_t ofs; 171 172 /* note: just in case someone wrote the 173 magic character five months ago... */ 174 wdt_expect_close = 0; 175 176 /* scan to see whether or not we got the 177 magic character */ 178 for (ofs = 0; ofs != count; ofs++) { 179 char c; 180 if (get_user(c, buf + ofs)) 181 return -EFAULT; 182 if (c == 'V') 183 wdt_expect_close = 42; 184 } 185 } 186 187 /* Well, anyhow someone wrote to us, we should 188 return that favour */ 189 wdt_keepalive(); 190 } 191 return count; 192 } 193 194 static int fop_open(struct inode *inode, struct file *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 stream_open(inode, file); 206 } 207 208 static 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 pr_crit("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 } 220 221 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 222 { 223 void __user *argp = (void __user *)arg; 224 int __user *p = argp; 225 static const struct watchdog_info ident = { 226 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | 227 WDIOF_MAGICCLOSE, 228 .firmware_version = 1, 229 .identity = "SBC60xx", 230 }; 231 232 switch (cmd) { 233 case WDIOC_GETSUPPORT: 234 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; 235 case WDIOC_GETSTATUS: 236 case WDIOC_GETBOOTSTATUS: 237 return put_user(0, p); 238 case WDIOC_SETOPTIONS: 239 { 240 int new_options, retval = -EINVAL; 241 if (get_user(new_options, p)) 242 return -EFAULT; 243 if (new_options & WDIOS_DISABLECARD) { 244 wdt_turnoff(); 245 retval = 0; 246 } 247 if (new_options & WDIOS_ENABLECARD) { 248 wdt_startup(); 249 retval = 0; 250 } 251 return retval; 252 } 253 case WDIOC_KEEPALIVE: 254 wdt_keepalive(); 255 return 0; 256 case WDIOC_SETTIMEOUT: 257 { 258 int new_timeout; 259 if (get_user(new_timeout, p)) 260 return -EFAULT; 261 /* arbitrary upper limit */ 262 if (new_timeout < 1 || new_timeout > 3600) 263 return -EINVAL; 264 265 timeout = new_timeout; 266 wdt_keepalive(); 267 } 268 fallthrough; 269 case WDIOC_GETTIMEOUT: 270 return put_user(timeout, p); 271 default: 272 return -ENOTTY; 273 } 274 } 275 276 static const struct file_operations wdt_fops = { 277 .owner = THIS_MODULE, 278 .llseek = no_llseek, 279 .write = fop_write, 280 .open = fop_open, 281 .release = fop_close, 282 .unlocked_ioctl = fop_ioctl, 283 .compat_ioctl = compat_ptr_ioctl, 284 }; 285 286 static struct miscdevice wdt_miscdev = { 287 .minor = WATCHDOG_MINOR, 288 .name = "watchdog", 289 .fops = &wdt_fops, 290 }; 291 292 /* 293 * Notifier for system down 294 */ 295 296 static int wdt_notify_sys(struct notifier_block *this, unsigned long code, 297 void *unused) 298 { 299 if (code == SYS_DOWN || code == SYS_HALT) 300 wdt_turnoff(); 301 return NOTIFY_DONE; 302 } 303 304 /* 305 * The WDT needs to learn about soft shutdowns in order to 306 * turn the timebomb registers off. 307 */ 308 309 static struct notifier_block wdt_notifier = { 310 .notifier_call = wdt_notify_sys, 311 }; 312 313 static void __exit sbc60xxwdt_unload(void) 314 { 315 wdt_turnoff(); 316 317 /* Deregister */ 318 misc_deregister(&wdt_miscdev); 319 320 unregister_reboot_notifier(&wdt_notifier); 321 if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) 322 release_region(wdt_stop, 1); 323 release_region(wdt_start, 1); 324 } 325 326 static int __init sbc60xxwdt_init(void) 327 { 328 int rc = -EBUSY; 329 330 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ 331 timeout = WATCHDOG_TIMEOUT; 332 pr_info("timeout value must be 1 <= x <= 3600, using %d\n", 333 timeout); 334 } 335 336 if (!request_region(wdt_start, 1, "SBC 60XX WDT")) { 337 pr_err("I/O address 0x%04x already in use\n", wdt_start); 338 rc = -EIO; 339 goto err_out; 340 } 341 342 /* We cannot reserve 0x45 - the kernel already has! */ 343 if (wdt_stop != 0x45 && wdt_stop != wdt_start) { 344 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) { 345 pr_err("I/O address 0x%04x already in use\n", wdt_stop); 346 rc = -EIO; 347 goto err_out_region1; 348 } 349 } 350 351 rc = register_reboot_notifier(&wdt_notifier); 352 if (rc) { 353 pr_err("cannot register reboot notifier (err=%d)\n", rc); 354 goto err_out_region2; 355 } 356 357 rc = misc_register(&wdt_miscdev); 358 if (rc) { 359 pr_err("cannot register miscdev on minor=%d (err=%d)\n", 360 wdt_miscdev.minor, rc); 361 goto err_out_reboot; 362 } 363 pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", 364 timeout, nowayout); 365 366 return 0; 367 368 err_out_reboot: 369 unregister_reboot_notifier(&wdt_notifier); 370 err_out_region2: 371 if (wdt_stop != 0x45 && wdt_stop != wdt_start) 372 release_region(wdt_stop, 1); 373 err_out_region1: 374 release_region(wdt_start, 1); 375 err_out: 376 return rc; 377 } 378 379 module_init(sbc60xxwdt_init); 380 module_exit(sbc60xxwdt_unload); 381 382 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); 383 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); 384 MODULE_LICENSE("GPL"); 385