1 /* 2 * MachZ ZF-Logic Watchdog Timer driver for Linux 3 * 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 * 10 * The author does NOT admit liability nor provide warranty for 11 * any of this software. This material is provided "AS-IS" in 12 * the hope that it may be useful for others. 13 * 14 * Author: Fernando Fuganti <fuganti@conectiva.com.br> 15 * 16 * Based on sbc60xxwdt.c by Jakob Oestergaard 17 * 18 * 19 * We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the 20 * following periods: 21 * wd#1 - 2 seconds; 22 * wd#2 - 7.2 ms; 23 * After the expiration of wd#1, it can generate a NMI, SCI, SMI, or 24 * a system RESET and it starts wd#2 that unconditionally will RESET 25 * the system when the counter reaches zero. 26 * 27 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> 28 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT 29 */ 30 31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 32 33 #include <linux/module.h> 34 #include <linux/moduleparam.h> 35 #include <linux/types.h> 36 #include <linux/timer.h> 37 #include <linux/jiffies.h> 38 #include <linux/miscdevice.h> 39 #include <linux/watchdog.h> 40 #include <linux/fs.h> 41 #include <linux/ioport.h> 42 #include <linux/notifier.h> 43 #include <linux/reboot.h> 44 #include <linux/init.h> 45 #include <linux/io.h> 46 #include <linux/uaccess.h> 47 48 49 /* ports */ 50 #define ZF_IOBASE 0x218 51 #define INDEX 0x218 52 #define DATA_B 0x219 53 #define DATA_W 0x21A 54 #define DATA_D 0x21A 55 56 /* indexes */ /* size */ 57 #define ZFL_VERSION 0x02 /* 16 */ 58 #define CONTROL 0x10 /* 16 */ 59 #define STATUS 0x12 /* 8 */ 60 #define COUNTER_1 0x0C /* 16 */ 61 #define COUNTER_2 0x0E /* 8 */ 62 #define PULSE_LEN 0x0F /* 8 */ 63 64 /* controls */ 65 #define ENABLE_WD1 0x0001 66 #define ENABLE_WD2 0x0002 67 #define RESET_WD1 0x0010 68 #define RESET_WD2 0x0020 69 #define GEN_SCI 0x0100 70 #define GEN_NMI 0x0200 71 #define GEN_SMI 0x0400 72 #define GEN_RESET 0x0800 73 74 75 /* utilities */ 76 77 #define WD1 0 78 #define WD2 1 79 80 #define zf_writew(port, data) { outb(port, INDEX); outw(data, DATA_W); } 81 #define zf_writeb(port, data) { outb(port, INDEX); outb(data, DATA_B); } 82 #define zf_get_ZFL_version() zf_readw(ZFL_VERSION) 83 84 85 static unsigned short zf_readw(unsigned char port) 86 { 87 outb(port, INDEX); 88 return inw(DATA_W); 89 } 90 91 92 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>"); 93 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver"); 94 MODULE_LICENSE("GPL"); 95 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); 96 97 static bool nowayout = WATCHDOG_NOWAYOUT; 98 module_param(nowayout, bool, 0); 99 MODULE_PARM_DESC(nowayout, 100 "Watchdog cannot be stopped once started (default=" 101 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 102 103 #define PFX "machzwd" 104 105 static const struct watchdog_info zf_info = { 106 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 107 .firmware_version = 1, 108 .identity = "ZF-Logic watchdog", 109 }; 110 111 112 /* 113 * action refers to action taken when watchdog resets 114 * 0 = GEN_RESET 115 * 1 = GEN_SMI 116 * 2 = GEN_NMI 117 * 3 = GEN_SCI 118 * defaults to GEN_RESET (0) 119 */ 120 static int action; 121 module_param(action, int, 0); 122 MODULE_PARM_DESC(action, "after watchdog resets, generate: " 123 "0 = RESET(*) 1 = SMI 2 = NMI 3 = SCI"); 124 125 static void zf_ping(unsigned long data); 126 127 static int zf_action = GEN_RESET; 128 static unsigned long zf_is_open; 129 static char zf_expect_close; 130 static DEFINE_SPINLOCK(zf_port_lock); 131 static DEFINE_TIMER(zf_timer, zf_ping, 0, 0); 132 static unsigned long next_heartbeat; 133 134 135 /* timeout for user land heart beat (10 seconds) */ 136 #define ZF_USER_TIMEO (HZ*10) 137 138 /* timeout for hardware watchdog (~500ms) */ 139 #define ZF_HW_TIMEO (HZ/2) 140 141 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */ 142 #define ZF_CTIMEOUT 0xffff 143 144 #ifndef ZF_DEBUG 145 #define dprintk(format, args...) 146 #else 147 #define dprintk(format, args...) \ 148 pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args) 149 #endif 150 151 152 static inline void zf_set_status(unsigned char new) 153 { 154 zf_writeb(STATUS, new); 155 } 156 157 158 /* CONTROL register functions */ 159 160 static inline unsigned short zf_get_control(void) 161 { 162 return zf_readw(CONTROL); 163 } 164 165 static inline void zf_set_control(unsigned short new) 166 { 167 zf_writew(CONTROL, new); 168 } 169 170 171 /* WD#? counter functions */ 172 /* 173 * Just set counter value 174 */ 175 176 static inline void zf_set_timer(unsigned short new, unsigned char n) 177 { 178 switch (n) { 179 case WD1: 180 zf_writew(COUNTER_1, new); 181 case WD2: 182 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new); 183 default: 184 return; 185 } 186 } 187 188 /* 189 * stop hardware timer 190 */ 191 static void zf_timer_off(void) 192 { 193 unsigned int ctrl_reg = 0; 194 unsigned long flags; 195 196 /* stop internal ping */ 197 del_timer_sync(&zf_timer); 198 199 spin_lock_irqsave(&zf_port_lock, flags); 200 /* stop watchdog timer */ 201 ctrl_reg = zf_get_control(); 202 ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */ 203 ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2); 204 zf_set_control(ctrl_reg); 205 spin_unlock_irqrestore(&zf_port_lock, flags); 206 207 pr_info("Watchdog timer is now disabled\n"); 208 } 209 210 211 /* 212 * start hardware timer 213 */ 214 static void zf_timer_on(void) 215 { 216 unsigned int ctrl_reg = 0; 217 unsigned long flags; 218 219 spin_lock_irqsave(&zf_port_lock, flags); 220 221 zf_writeb(PULSE_LEN, 0xff); 222 223 zf_set_timer(ZF_CTIMEOUT, WD1); 224 225 /* user land ping */ 226 next_heartbeat = jiffies + ZF_USER_TIMEO; 227 228 /* start the timer for internal ping */ 229 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO); 230 231 /* start watchdog timer */ 232 ctrl_reg = zf_get_control(); 233 ctrl_reg |= (ENABLE_WD1|zf_action); 234 zf_set_control(ctrl_reg); 235 spin_unlock_irqrestore(&zf_port_lock, flags); 236 237 pr_info("Watchdog timer is now enabled\n"); 238 } 239 240 241 static void zf_ping(unsigned long data) 242 { 243 unsigned int ctrl_reg = 0; 244 unsigned long flags; 245 246 zf_writeb(COUNTER_2, 0xff); 247 248 if (time_before(jiffies, next_heartbeat)) { 249 dprintk("time_before: %ld\n", next_heartbeat - jiffies); 250 /* 251 * reset event is activated by transition from 0 to 1 on 252 * RESET_WD1 bit and we assume that it is already zero... 253 */ 254 255 spin_lock_irqsave(&zf_port_lock, flags); 256 ctrl_reg = zf_get_control(); 257 ctrl_reg |= RESET_WD1; 258 zf_set_control(ctrl_reg); 259 260 /* ...and nothing changes until here */ 261 ctrl_reg &= ~(RESET_WD1); 262 zf_set_control(ctrl_reg); 263 spin_unlock_irqrestore(&zf_port_lock, flags); 264 265 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO); 266 } else 267 pr_crit("I will reset your machine\n"); 268 } 269 270 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count, 271 loff_t *ppos) 272 { 273 /* See if we got the magic character */ 274 if (count) { 275 /* 276 * no need to check for close confirmation 277 * no way to disable watchdog ;) 278 */ 279 if (!nowayout) { 280 size_t ofs; 281 /* 282 * note: just in case someone wrote the magic character 283 * five months ago... 284 */ 285 zf_expect_close = 0; 286 287 /* now scan */ 288 for (ofs = 0; ofs != count; ofs++) { 289 char c; 290 if (get_user(c, buf + ofs)) 291 return -EFAULT; 292 if (c == 'V') { 293 zf_expect_close = 42; 294 dprintk("zf_expect_close = 42\n"); 295 } 296 } 297 } 298 299 /* 300 * Well, anyhow someone wrote to us, 301 * we should return that favour 302 */ 303 next_heartbeat = jiffies + ZF_USER_TIMEO; 304 dprintk("user ping at %ld\n", jiffies); 305 } 306 return count; 307 } 308 309 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 310 { 311 void __user *argp = (void __user *)arg; 312 int __user *p = argp; 313 switch (cmd) { 314 case WDIOC_GETSUPPORT: 315 if (copy_to_user(argp, &zf_info, sizeof(zf_info))) 316 return -EFAULT; 317 break; 318 case WDIOC_GETSTATUS: 319 case WDIOC_GETBOOTSTATUS: 320 return put_user(0, p); 321 case WDIOC_KEEPALIVE: 322 zf_ping(0); 323 break; 324 default: 325 return -ENOTTY; 326 } 327 return 0; 328 } 329 330 static int zf_open(struct inode *inode, struct file *file) 331 { 332 if (test_and_set_bit(0, &zf_is_open)) 333 return -EBUSY; 334 if (nowayout) 335 __module_get(THIS_MODULE); 336 zf_timer_on(); 337 return nonseekable_open(inode, file); 338 } 339 340 static int zf_close(struct inode *inode, struct file *file) 341 { 342 if (zf_expect_close == 42) 343 zf_timer_off(); 344 else { 345 del_timer(&zf_timer); 346 pr_err("device file closed unexpectedly. Will not stop the WDT!\n"); 347 } 348 clear_bit(0, &zf_is_open); 349 zf_expect_close = 0; 350 return 0; 351 } 352 353 /* 354 * Notifier for system down 355 */ 356 357 static int zf_notify_sys(struct notifier_block *this, unsigned long code, 358 void *unused) 359 { 360 if (code == SYS_DOWN || code == SYS_HALT) 361 zf_timer_off(); 362 return NOTIFY_DONE; 363 } 364 365 static const struct file_operations zf_fops = { 366 .owner = THIS_MODULE, 367 .llseek = no_llseek, 368 .write = zf_write, 369 .unlocked_ioctl = zf_ioctl, 370 .open = zf_open, 371 .release = zf_close, 372 }; 373 374 static struct miscdevice zf_miscdev = { 375 .minor = WATCHDOG_MINOR, 376 .name = "watchdog", 377 .fops = &zf_fops, 378 }; 379 380 381 /* 382 * The device needs to learn about soft shutdowns in order to 383 * turn the timebomb registers off. 384 */ 385 static struct notifier_block zf_notifier = { 386 .notifier_call = zf_notify_sys, 387 }; 388 389 static void __init zf_show_action(int act) 390 { 391 static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" }; 392 393 pr_info("Watchdog using action = %s\n", str[act]); 394 } 395 396 static int __init zf_init(void) 397 { 398 int ret; 399 400 pr_info("MachZ ZF-Logic Watchdog driver initializing\n"); 401 402 ret = zf_get_ZFL_version(); 403 if (!ret || ret == 0xffff) { 404 pr_warn("no ZF-Logic found\n"); 405 return -ENODEV; 406 } 407 408 if (action <= 3 && action >= 0) 409 zf_action = zf_action >> action; 410 else 411 action = 0; 412 413 zf_show_action(action); 414 415 if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) { 416 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE); 417 ret = -EBUSY; 418 goto no_region; 419 } 420 421 ret = register_reboot_notifier(&zf_notifier); 422 if (ret) { 423 pr_err("can't register reboot notifier (err=%d)\n", ret); 424 goto no_reboot; 425 } 426 427 ret = misc_register(&zf_miscdev); 428 if (ret) { 429 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR); 430 goto no_misc; 431 } 432 433 zf_set_status(0); 434 zf_set_control(0); 435 436 return 0; 437 438 no_misc: 439 unregister_reboot_notifier(&zf_notifier); 440 no_reboot: 441 release_region(ZF_IOBASE, 3); 442 no_region: 443 return ret; 444 } 445 446 447 static void __exit zf_exit(void) 448 { 449 zf_timer_off(); 450 451 misc_deregister(&zf_miscdev); 452 unregister_reboot_notifier(&zf_notifier); 453 release_region(ZF_IOBASE, 3); 454 } 455 456 module_init(zf_init); 457 module_exit(zf_exit); 458