1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * SBC8360 Watchdog driver 4 * 5 * (c) Copyright 2005 Webcon, Inc. 6 * 7 * Based on ib700wdt.c, which is based on advantechwdt.c which is based 8 * on acquirewdt.c which is based on wdt.c. 9 * 10 * (c) Copyright 2001 Charles Howes <chowes@vsol.net> 11 * 12 * Based on advantechwdt.c which is based on acquirewdt.c which 13 * is based on wdt.c. 14 * 15 * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl> 16 * 17 * Based on acquirewdt.c which is based on wdt.c. 18 * Original copyright messages: 19 * 20 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, 21 * All Rights Reserved. 22 * 23 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide 24 * warranty for any of this software. This material is provided 25 * "AS-IS" and at no charge. 26 * 27 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> 28 * 29 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> 30 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT 31 * Added timeout module option to override default 32 * 33 */ 34 35 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 36 37 #include <linux/module.h> 38 #include <linux/types.h> 39 #include <linux/miscdevice.h> 40 #include <linux/watchdog.h> 41 #include <linux/ioport.h> 42 #include <linux/delay.h> 43 #include <linux/notifier.h> 44 #include <linux/fs.h> 45 #include <linux/reboot.h> 46 #include <linux/init.h> 47 #include <linux/spinlock.h> 48 #include <linux/moduleparam.h> 49 #include <linux/io.h> 50 #include <linux/uaccess.h> 51 52 53 static unsigned long sbc8360_is_open; 54 static char expect_close; 55 56 /* 57 * 58 * Watchdog Timer Configuration 59 * 60 * The function of the watchdog timer is to reset the system automatically 61 * and is defined at I/O port 0120H and 0121H. To enable the watchdog timer 62 * and allow the system to reset, write appropriate values from the table 63 * below to I/O port 0120H and 0121H. To disable the timer, write a zero 64 * value to I/O port 0121H for the system to stop the watchdog function. 65 * 66 * The following describes how the timer should be programmed (according to 67 * the vendor documentation) 68 * 69 * Enabling Watchdog: 70 * MOV AX,000AH (enable, phase I) 71 * MOV DX,0120H 72 * OUT DX,AX 73 * MOV AX,000BH (enable, phase II) 74 * MOV DX,0120H 75 * OUT DX,AX 76 * MOV AX,000nH (set multiplier n, from 1-4) 77 * MOV DX,0120H 78 * OUT DX,AX 79 * MOV AX,000mH (set base timer m, from 0-F) 80 * MOV DX,0121H 81 * OUT DX,AX 82 * 83 * Reset timer: 84 * MOV AX,000mH (same as set base timer, above) 85 * MOV DX,0121H 86 * OUT DX,AX 87 * 88 * Disabling Watchdog: 89 * MOV AX,0000H (a zero value) 90 * MOV DX,0120H 91 * OUT DX,AX 92 * 93 * Watchdog timeout configuration values: 94 * N 95 * M | 1 2 3 4 96 * --|---------------------------------- 97 * 0 | 0.5s 5s 50s 100s 98 * 1 | 1s 10s 100s 200s 99 * 2 | 1.5s 15s 150s 300s 100 * 3 | 2s 20s 200s 400s 101 * 4 | 2.5s 25s 250s 500s 102 * 5 | 3s 30s 300s 600s 103 * 6 | 3.5s 35s 350s 700s 104 * 7 | 4s 40s 400s 800s 105 * 8 | 4.5s 45s 450s 900s 106 * 9 | 5s 50s 500s 1000s 107 * A | 5.5s 55s 550s 1100s 108 * B | 6s 60s 600s 1200s 109 * C | 6.5s 65s 650s 1300s 110 * D | 7s 70s 700s 1400s 111 * E | 7.5s 75s 750s 1500s 112 * F | 8s 80s 800s 1600s 113 * 114 * Another way to say the same things is: 115 * For N=1, Timeout = (M+1) * 0.5s 116 * For N=2, Timeout = (M+1) * 5s 117 * For N=3, Timeout = (M+1) * 50s 118 * For N=4, Timeout = (M+1) * 100s 119 * 120 */ 121 122 static int wd_times[64][2] = { 123 {0, 1}, /* 0 = 0.5s */ 124 {1, 1}, /* 1 = 1s */ 125 {2, 1}, /* 2 = 1.5s */ 126 {3, 1}, /* 3 = 2s */ 127 {4, 1}, /* 4 = 2.5s */ 128 {5, 1}, /* 5 = 3s */ 129 {6, 1}, /* 6 = 3.5s */ 130 {7, 1}, /* 7 = 4s */ 131 {8, 1}, /* 8 = 4.5s */ 132 {9, 1}, /* 9 = 5s */ 133 {0xA, 1}, /* 10 = 5.5s */ 134 {0xB, 1}, /* 11 = 6s */ 135 {0xC, 1}, /* 12 = 6.5s */ 136 {0xD, 1}, /* 13 = 7s */ 137 {0xE, 1}, /* 14 = 7.5s */ 138 {0xF, 1}, /* 15 = 8s */ 139 {0, 2}, /* 16 = 5s */ 140 {1, 2}, /* 17 = 10s */ 141 {2, 2}, /* 18 = 15s */ 142 {3, 2}, /* 19 = 20s */ 143 {4, 2}, /* 20 = 25s */ 144 {5, 2}, /* 21 = 30s */ 145 {6, 2}, /* 22 = 35s */ 146 {7, 2}, /* 23 = 40s */ 147 {8, 2}, /* 24 = 45s */ 148 {9, 2}, /* 25 = 50s */ 149 {0xA, 2}, /* 26 = 55s */ 150 {0xB, 2}, /* 27 = 60s */ 151 {0xC, 2}, /* 28 = 65s */ 152 {0xD, 2}, /* 29 = 70s */ 153 {0xE, 2}, /* 30 = 75s */ 154 {0xF, 2}, /* 31 = 80s */ 155 {0, 3}, /* 32 = 50s */ 156 {1, 3}, /* 33 = 100s */ 157 {2, 3}, /* 34 = 150s */ 158 {3, 3}, /* 35 = 200s */ 159 {4, 3}, /* 36 = 250s */ 160 {5, 3}, /* 37 = 300s */ 161 {6, 3}, /* 38 = 350s */ 162 {7, 3}, /* 39 = 400s */ 163 {8, 3}, /* 40 = 450s */ 164 {9, 3}, /* 41 = 500s */ 165 {0xA, 3}, /* 42 = 550s */ 166 {0xB, 3}, /* 43 = 600s */ 167 {0xC, 3}, /* 44 = 650s */ 168 {0xD, 3}, /* 45 = 700s */ 169 {0xE, 3}, /* 46 = 750s */ 170 {0xF, 3}, /* 47 = 800s */ 171 {0, 4}, /* 48 = 100s */ 172 {1, 4}, /* 49 = 200s */ 173 {2, 4}, /* 50 = 300s */ 174 {3, 4}, /* 51 = 400s */ 175 {4, 4}, /* 52 = 500s */ 176 {5, 4}, /* 53 = 600s */ 177 {6, 4}, /* 54 = 700s */ 178 {7, 4}, /* 55 = 800s */ 179 {8, 4}, /* 56 = 900s */ 180 {9, 4}, /* 57 = 1000s */ 181 {0xA, 4}, /* 58 = 1100s */ 182 {0xB, 4}, /* 59 = 1200s */ 183 {0xC, 4}, /* 60 = 1300s */ 184 {0xD, 4}, /* 61 = 1400s */ 185 {0xE, 4}, /* 62 = 1500s */ 186 {0xF, 4} /* 63 = 1600s */ 187 }; 188 189 #define SBC8360_ENABLE 0x120 190 #define SBC8360_BASETIME 0x121 191 192 static int timeout = 27; 193 static int wd_margin = 0xB; 194 static int wd_multiplier = 2; 195 static bool nowayout = WATCHDOG_NOWAYOUT; 196 197 module_param(timeout, int, 0); 198 MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))"); 199 module_param(nowayout, bool, 0); 200 MODULE_PARM_DESC(nowayout, 201 "Watchdog cannot be stopped once started (default=" 202 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 203 204 /* 205 * Kernel methods. 206 */ 207 208 /* Activate and pre-configure watchdog */ 209 static void sbc8360_activate(void) 210 { 211 /* Enable the watchdog */ 212 outb(0x0A, SBC8360_ENABLE); 213 msleep_interruptible(100); 214 outb(0x0B, SBC8360_ENABLE); 215 msleep_interruptible(100); 216 /* Set timeout multiplier */ 217 outb(wd_multiplier, SBC8360_ENABLE); 218 msleep_interruptible(100); 219 /* Nothing happens until first sbc8360_ping() */ 220 } 221 222 /* Kernel pings watchdog */ 223 static void sbc8360_ping(void) 224 { 225 /* Write the base timer register */ 226 outb(wd_margin, SBC8360_BASETIME); 227 } 228 229 /* stop watchdog */ 230 static void sbc8360_stop(void) 231 { 232 /* De-activate the watchdog */ 233 outb(0, SBC8360_ENABLE); 234 } 235 236 /* Userspace pings kernel driver, or requests clean close */ 237 static ssize_t sbc8360_write(struct file *file, const char __user *buf, 238 size_t count, loff_t *ppos) 239 { 240 if (count) { 241 if (!nowayout) { 242 size_t i; 243 244 /* In case it was set long ago */ 245 expect_close = 0; 246 247 for (i = 0; i != count; i++) { 248 char c; 249 if (get_user(c, buf + i)) 250 return -EFAULT; 251 if (c == 'V') 252 expect_close = 42; 253 } 254 } 255 sbc8360_ping(); 256 } 257 return count; 258 } 259 260 static int sbc8360_open(struct inode *inode, struct file *file) 261 { 262 if (test_and_set_bit(0, &sbc8360_is_open)) 263 return -EBUSY; 264 if (nowayout) 265 __module_get(THIS_MODULE); 266 267 /* Activate and ping once to start the countdown */ 268 sbc8360_activate(); 269 sbc8360_ping(); 270 return stream_open(inode, file); 271 } 272 273 static int sbc8360_close(struct inode *inode, struct file *file) 274 { 275 if (expect_close == 42) 276 sbc8360_stop(); 277 else 278 pr_crit("SBC8360 device closed unexpectedly. SBC8360 will not stop!\n"); 279 280 clear_bit(0, &sbc8360_is_open); 281 expect_close = 0; 282 return 0; 283 } 284 285 /* 286 * Notifier for system down 287 */ 288 289 static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code, 290 void *unused) 291 { 292 if (code == SYS_DOWN || code == SYS_HALT) 293 sbc8360_stop(); /* Disable the SBC8360 Watchdog */ 294 295 return NOTIFY_DONE; 296 } 297 298 /* 299 * Kernel Interfaces 300 */ 301 302 static const struct file_operations sbc8360_fops = { 303 .owner = THIS_MODULE, 304 .llseek = no_llseek, 305 .write = sbc8360_write, 306 .open = sbc8360_open, 307 .release = sbc8360_close, 308 }; 309 310 static struct miscdevice sbc8360_miscdev = { 311 .minor = WATCHDOG_MINOR, 312 .name = "watchdog", 313 .fops = &sbc8360_fops, 314 }; 315 316 /* 317 * The SBC8360 needs to learn about soft shutdowns in order to 318 * turn the timebomb registers off. 319 */ 320 321 static struct notifier_block sbc8360_notifier = { 322 .notifier_call = sbc8360_notify_sys, 323 }; 324 325 static int __init sbc8360_init(void) 326 { 327 int res; 328 unsigned long int mseconds = 60000; 329 330 if (timeout < 0 || timeout > 63) { 331 pr_err("Invalid timeout index (must be 0-63)\n"); 332 res = -EINVAL; 333 goto out; 334 } 335 336 if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) { 337 pr_err("ENABLE method I/O %X is not available\n", 338 SBC8360_ENABLE); 339 res = -EIO; 340 goto out; 341 } 342 if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) { 343 pr_err("BASETIME method I/O %X is not available\n", 344 SBC8360_BASETIME); 345 res = -EIO; 346 goto out_nobasetimereg; 347 } 348 349 res = register_reboot_notifier(&sbc8360_notifier); 350 if (res) { 351 pr_err("Failed to register reboot notifier\n"); 352 goto out_noreboot; 353 } 354 355 res = misc_register(&sbc8360_miscdev); 356 if (res) { 357 pr_err("failed to register misc device\n"); 358 goto out_nomisc; 359 } 360 361 wd_margin = wd_times[timeout][0]; 362 wd_multiplier = wd_times[timeout][1]; 363 364 if (wd_multiplier == 1) 365 mseconds = (wd_margin + 1) * 500; 366 else if (wd_multiplier == 2) 367 mseconds = (wd_margin + 1) * 5000; 368 else if (wd_multiplier == 3) 369 mseconds = (wd_margin + 1) * 50000; 370 else if (wd_multiplier == 4) 371 mseconds = (wd_margin + 1) * 100000; 372 373 /* My kingdom for the ability to print "0.5 seconds" in the kernel! */ 374 pr_info("Timeout set at %ld ms\n", mseconds); 375 376 return 0; 377 378 out_nomisc: 379 unregister_reboot_notifier(&sbc8360_notifier); 380 out_noreboot: 381 release_region(SBC8360_BASETIME, 1); 382 out_nobasetimereg: 383 release_region(SBC8360_ENABLE, 1); 384 out: 385 return res; 386 } 387 388 static void __exit sbc8360_exit(void) 389 { 390 misc_deregister(&sbc8360_miscdev); 391 unregister_reboot_notifier(&sbc8360_notifier); 392 release_region(SBC8360_ENABLE, 1); 393 release_region(SBC8360_BASETIME, 1); 394 } 395 396 module_init(sbc8360_init); 397 module_exit(sbc8360_exit); 398 399 MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>"); 400 MODULE_DESCRIPTION("SBC8360 watchdog driver"); 401 MODULE_LICENSE("GPL"); 402 MODULE_VERSION("1.01"); 403 404 /* end of sbc8360.c */ 405