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 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);