drivers/watchdog/machzwd.c

   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
  96 static bool nowayout = WATCHDOG_NOWAYOUT;
  97 module_param(nowayout, bool, 0);
  98 MODULE_PARM_DESC(nowayout,
  99                 "Watchdog cannot be stopped once started (default="
 100                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 101
 102 #define PFX "machzwd"
 103
 104 static const struct watchdog_info zf_info = {
 105         .options                = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 106         .firmware_version       = 1,
 107         .identity               = "ZF-Logic watchdog",
 108 };
 109
 110
 111 /*
 112  * action refers to action taken when watchdog resets
 113  * 0 = GEN_RESET
 114  * 1 = GEN_SMI
 115  * 2 = GEN_NMI
 116  * 3 = GEN_SCI
 117  * defaults to GEN_RESET (0)
 118  */
 119 static int action;
 120 module_param(action, int, 0);
 121 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
 122                                 "0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 123
 124 static void zf_ping(struct timer_list *unused);
 125
 126 static int zf_action = GEN_RESET;
 127 static unsigned long zf_is_open;
 128 static char zf_expect_close;
 129 static DEFINE_SPINLOCK(zf_port_lock);
 130 static DEFINE_TIMER(zf_timer, zf_ping);
 131 static unsigned long next_heartbeat;
 132
 133
 134 /* timeout for user land heart beat (10 seconds) */
 135 #define ZF_USER_TIMEO (HZ*10)
 136
 137 /* timeout for hardware watchdog (~500ms) */
 138 #define ZF_HW_TIMEO (HZ/2)
 139
 140 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 141 #define ZF_CTIMEOUT 0xffff
 142
 143 #ifndef ZF_DEBUG
 144 #define dprintk(format, args...)
 145 #else
 146 #define dprintk(format, args...)                                        \
 147         pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
 148 #endif
 149
 150
 151 static inline void zf_set_status(unsigned char new)
 152 {
 153         zf_writeb(STATUS, new);
 154 }
 155
 156
 157 /* CONTROL register functions */
 158
 159 static inline unsigned short zf_get_control(void)
 160 {
 161         return zf_readw(CONTROL);
 162 }
 163
 164 static inline void zf_set_control(unsigned short new)
 165 {
 166         zf_writew(CONTROL, new);
 167 }
 168
 169
 170 /* WD#? counter functions */
 171 /*
 172  *      Just set counter value
 173  */
 174
 175 static inline void zf_set_timer(unsigned short new, unsigned char n)
 176 {
 177         switch (n) {
 178         case WD1:
 179                 zf_writew(COUNTER_1, new);
 180         case WD2:
 181                 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 182         default:
 183                 return;
 184         }
 185 }
 186
 187 /*
 188  * stop hardware timer
 189  */
 190 static void zf_timer_off(void)
 191 {
 192         unsigned int ctrl_reg = 0;
 193         unsigned long flags;
 194
 195         /* stop internal ping */
 196         del_timer_sync(&zf_timer);
 197
 198         spin_lock_irqsave(&zf_port_lock, flags);
 199         /* stop watchdog timer */
 200         ctrl_reg = zf_get_control();
 201         ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 202         ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 203         zf_set_control(ctrl_reg);
 204         spin_unlock_irqrestore(&zf_port_lock, flags);
 205
 206         pr_info("Watchdog timer is now disabled\n");
 207 }
 208
 209
 210 /*
 211  * start hardware timer
 212  */
 213 static void zf_timer_on(void)
 214 {
 215         unsigned int ctrl_reg = 0;
 216         unsigned long flags;
 217
 218         spin_lock_irqsave(&zf_port_lock, flags);
 219
 220         zf_writeb(PULSE_LEN, 0xff);
 221
 222         zf_set_timer(ZF_CTIMEOUT, WD1);
 223
 224         /* user land ping */
 225         next_heartbeat = jiffies + ZF_USER_TIMEO;
 226
 227         /* start the timer for internal ping */
 228         mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 229
 230         /* start watchdog timer */
 231         ctrl_reg = zf_get_control();
 232         ctrl_reg |= (ENABLE_WD1|zf_action);
 233         zf_set_control(ctrl_reg);
 234         spin_unlock_irqrestore(&zf_port_lock, flags);
 235
 236         pr_info("Watchdog timer is now enabled\n");
 237 }
 238
 239
 240 static void zf_ping(struct timer_list *unused)
 241 {
 242         unsigned int ctrl_reg = 0;
 243         unsigned long flags;
 244
 245         zf_writeb(COUNTER_2, 0xff);
 246
 247         if (time_before(jiffies, next_heartbeat)) {
 248                 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
 249                 /*
 250                  * reset event is activated by transition from 0 to 1 on
 251                  * RESET_WD1 bit and we assume that it is already zero...
 252                  */
 253
 254                 spin_lock_irqsave(&zf_port_lock, flags);
 255                 ctrl_reg = zf_get_control();
 256                 ctrl_reg |= RESET_WD1;
 257                 zf_set_control(ctrl_reg);
 258
 259                 /* ...and nothing changes until here */
 260                 ctrl_reg &= ~(RESET_WD1);
 261                 zf_set_control(ctrl_reg);
 262                 spin_unlock_irqrestore(&zf_port_lock, flags);
 263
 264                 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 265         } else
 266                 pr_crit("I will reset your machine\n");
 267 }
 268
 269 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
 270                                                                 loff_t *ppos)
 271 {
 272         /* See if we got the magic character */
 273         if (count) {
 274                 /*
 275                  * no need to check for close confirmation
 276                  * no way to disable watchdog ;)
 277                  */
 278                 if (!nowayout) {
 279                         size_t ofs;
 280                         /*
 281                          * note: just in case someone wrote the magic character
 282                          * five months ago...
 283                          */
 284                         zf_expect_close = 0;
 285
 286                         /* now scan */
 287                         for (ofs = 0; ofs != count; ofs++) {
 288                                 char c;
 289                                 if (get_user(c, buf + ofs))
 290                                         return -EFAULT;
 291                                 if (c == 'V') {
 292                                         zf_expect_close = 42;
 293                                         dprintk("zf_expect_close = 42\n");
 294                                 }
 295                         }
 296                 }
 297
 298                 /*
 299                  * Well, anyhow someone wrote to us,
 300                  * we should return that favour
 301                  */
 302                 next_heartbeat = jiffies + ZF_USER_TIMEO;
 303                 dprintk("user ping at %ld\n", jiffies);
 304         }
 305         return count;
 306 }
 307
 308 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 309 {
 310         void __user *argp = (void __user *)arg;
 311         int __user *p = argp;
 312         switch (cmd) {
 313         case WDIOC_GETSUPPORT:
 314                 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 315                         return -EFAULT;
 316                 break;
 317         case WDIOC_GETSTATUS:
 318         case WDIOC_GETBOOTSTATUS:
 319                 return put_user(0, p);
 320         case WDIOC_KEEPALIVE:
 321                 zf_ping(0);
 322                 break;
 323         default:
 324                 return -ENOTTY;
 325         }
 326         return 0;
 327 }
 328
 329 static int zf_open(struct inode *inode, struct file *file)
 330 {
 331         if (test_and_set_bit(0, &zf_is_open))
 332                 return -EBUSY;
 333         if (nowayout)
 334                 __module_get(THIS_MODULE);
 335         zf_timer_on();
 336         return nonseekable_open(inode, file);
 337 }
 338
 339 static int zf_close(struct inode *inode, struct file *file)
 340 {
 341         if (zf_expect_close == 42)
 342                 zf_timer_off();
 343         else {
 344                 del_timer(&zf_timer);
 345                 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
 346         }
 347         clear_bit(0, &zf_is_open);
 348         zf_expect_close = 0;
 349         return 0;
 350 }
 351
 352 /*
 353  * Notifier for system down
 354  */
 355
 356 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 357                                                                 void *unused)
 358 {
 359         if (code == SYS_DOWN || code == SYS_HALT)
 360                 zf_timer_off();
 361         return NOTIFY_DONE;
 362 }
 363
 364 static const struct file_operations zf_fops = {
 365         .owner          = THIS_MODULE,
 366         .llseek         = no_llseek,
 367         .write          = zf_write,
 368         .unlocked_ioctl = zf_ioctl,
 369         .open           = zf_open,
 370         .release        = zf_close,
 371 };
 372
 373 static struct miscdevice zf_miscdev = {
 374         .minor = WATCHDOG_MINOR,
 375         .name = "watchdog",
 376         .fops = &zf_fops,
 377 };
 378
 379
 380 /*
 381  * The device needs to learn about soft shutdowns in order to
 382  * turn the timebomb registers off.
 383  */
 384 static struct notifier_block zf_notifier = {
 385         .notifier_call = zf_notify_sys,
 386 };
 387
 388 static void __init zf_show_action(int act)
 389 {
 390         static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
 391
 392         pr_info("Watchdog using action = %s\n", str[act]);
 393 }
 394
 395 static int __init zf_init(void)
 396 {
 397         int ret;
 398
 399         pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
 400
 401         ret = zf_get_ZFL_version();
 402         if (!ret || ret == 0xffff) {
 403                 pr_warn("no ZF-Logic found\n");
 404                 return -ENODEV;
 405         }
 406
 407         if (action <= 3 && action >= 0)
 408                 zf_action = zf_action >> action;
 409         else
 410                 action = 0;
 411
 412         zf_show_action(action);
 413
 414         if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
 415                 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
 416                 ret = -EBUSY;
 417                 goto no_region;
 418         }
 419
 420         ret = register_reboot_notifier(&zf_notifier);
 421         if (ret) {
 422                 pr_err("can't register reboot notifier (err=%d)\n", ret);
 423                 goto no_reboot;
 424         }
 425
 426         ret = misc_register(&zf_miscdev);
 427         if (ret) {
 428                 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
 429                 goto no_misc;
 430         }
 431
 432         zf_set_status(0);
 433         zf_set_control(0);
 434
 435         return 0;
 436
 437 no_misc:
 438         unregister_reboot_notifier(&zf_notifier);
 439 no_reboot:
 440         release_region(ZF_IOBASE, 3);
 441 no_region:
 442         return ret;
 443 }
 444
 445
 446 static void __exit zf_exit(void)
 447 {
 448         zf_timer_off();
 449
 450         misc_deregister(&zf_miscdev);
 451         unregister_reboot_notifier(&zf_notifier);
 452         release_region(ZF_IOBASE, 3);
 453 }
 454
 455 module_init(zf_init);
 456 module_exit(zf_exit);