drivers/char/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 unconditionaly 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 #include <linux/module.h>
  32 #include <linux/moduleparam.h>
  33 #include <linux/types.h>
  34 #include <linux/timer.h>
  35 #include <linux/jiffies.h>
  36 #include <linux/miscdevice.h>
  37 #include <linux/watchdog.h>
  38 #include <linux/fs.h>
  39 #include <linux/ioport.h>
  40 #include <linux/notifier.h>
  41 #include <linux/reboot.h>
  42 #include <linux/init.h>
  43
  44 #include <asm/io.h>
  45 #include <asm/uaccess.h>
  46 #include <asm/system.h>
  47
  48 /* ports */
  49 #define ZF_IOBASE       0x218
  50 #define INDEX           0x218
  51 #define DATA_B          0x219
  52 #define DATA_W          0x21A
  53 #define DATA_D          0x21A
  54
  55 /* indexes */                   /* size */
  56 #define ZFL_VERSION     0x02    /* 16   */
  57 #define CONTROL         0x10    /* 16   */
  58 #define STATUS          0x12    /* 8    */
  59 #define COUNTER_1       0x0C    /* 16   */
  60 #define COUNTER_2       0x0E    /* 8    */
  61 #define PULSE_LEN       0x0F    /* 8    */
  62
  63 /* controls */
  64 #define ENABLE_WD1      0x0001
  65 #define ENABLE_WD2      0x0002
  66 #define RESET_WD1       0x0010
  67 #define RESET_WD2       0x0020
  68 #define GEN_SCI         0x0100
  69 #define GEN_NMI         0x0200
  70 #define GEN_SMI         0x0400
  71 #define GEN_RESET       0x0800
  72
  73
  74 /* utilities */
  75
  76 #define WD1     0
  77 #define WD2     1
  78
  79 #define zf_writew(port, data)  { outb(port, INDEX); outw(data, DATA_W); }
  80 #define zf_writeb(port, data)  { outb(port, INDEX); outb(data, DATA_B); }
  81 #define zf_get_ZFL_version()   zf_readw(ZFL_VERSION)
  82
  83
  84 static unsigned short zf_readw(unsigned char port)
  85 {
  86         outb(port, INDEX);
  87         return inw(DATA_W);
  88 }
  89
  90
  91 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
  92 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
  93 MODULE_LICENSE("GPL");
  94 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  95
  96 static int nowayout = WATCHDOG_NOWAYOUT;
  97 module_param(nowayout, int, 0);
  98 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
  99
 100 #define PFX "machzwd"
 101
 102 static struct watchdog_info zf_info = {
 103         .options                = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 104         .firmware_version       = 1,
 105         .identity               = "ZF-Logic watchdog",
 106 };
 107
 108
 109 /*
 110  * action refers to action taken when watchdog resets
 111  * 0 = GEN_RESET
 112  * 1 = GEN_SMI
 113  * 2 = GEN_NMI
 114  * 3 = GEN_SCI
 115  * defaults to GEN_RESET (0)
 116  */
 117 static int action = 0;
 118 module_param(action, int, 0);
 119 MODULE_PARM_DESC(action, "after watchdog resets, generate: 0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 120
 121 static int zf_action = GEN_RESET;
 122 static unsigned long zf_is_open;
 123 static char zf_expect_close;
 124 static spinlock_t zf_lock;
 125 static spinlock_t zf_port_lock;
 126 static struct timer_list zf_timer;
 127 static unsigned long next_heartbeat = 0;
 128
 129
 130 /* timeout for user land heart beat (10 seconds) */
 131 #define ZF_USER_TIMEO (HZ*10)
 132
 133 /* timeout for hardware watchdog (~500ms) */
 134 #define ZF_HW_TIMEO (HZ/2)
 135
 136 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 137 #define ZF_CTIMEOUT 0xffff
 138
 139 #ifndef ZF_DEBUG
 140 #       define dprintk(format, args...)
 141 #else
 142 #       define dprintk(format, args...) printk(KERN_DEBUG PFX ":%s:%d: " format, __FUNCTION__, __LINE__ , ## args)
 143 #endif
 144
 145
 146 static inline void zf_set_status(unsigned char new)
 147 {
 148         zf_writeb(STATUS, new);
 149 }
 150
 151
 152 /* CONTROL register functions */
 153
 154 static inline unsigned short zf_get_control(void)
 155 {
 156         return zf_readw(CONTROL);
 157 }
 158
 159 static inline void zf_set_control(unsigned short new)
 160 {
 161         zf_writew(CONTROL, new);
 162 }
 163
 164
 165 /* WD#? counter functions */
 166 /*
 167  *      Just set counter value
 168  */
 169
 170 static inline void zf_set_timer(unsigned short new, unsigned char n)
 171 {
 172         switch(n){
 173                 case WD1:
 174                         zf_writew(COUNTER_1, new);
 175                 case WD2:
 176                         zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 177                 default:
 178                         return;
 179         }
 180 }
 181
 182 /*
 183  * stop hardware timer
 184  */
 185 static void zf_timer_off(void)
 186 {
 187         unsigned int ctrl_reg = 0;
 188         unsigned long flags;
 189
 190         /* stop internal ping */
 191         del_timer_sync(&zf_timer);
 192
 193         spin_lock_irqsave(&zf_port_lock, flags);
 194         /* stop watchdog timer */
 195         ctrl_reg = zf_get_control();
 196         ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 197         ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 198         zf_set_control(ctrl_reg);
 199         spin_unlock_irqrestore(&zf_port_lock, flags);
 200
 201         printk(KERN_INFO PFX ": Watchdog timer is now disabled\n");
 202 }
 203
 204
 205 /*
 206  * start hardware timer
 207  */
 208 static void zf_timer_on(void)
 209 {
 210         unsigned int ctrl_reg = 0;
 211         unsigned long flags;
 212
 213         spin_lock_irqsave(&zf_port_lock, flags);
 214
 215         zf_writeb(PULSE_LEN, 0xff);
 216
 217         zf_set_timer(ZF_CTIMEOUT, WD1);
 218
 219         /* user land ping */
 220         next_heartbeat = jiffies + ZF_USER_TIMEO;
 221
 222         /* start the timer for internal ping */
 223         zf_timer.expires = jiffies + ZF_HW_TIMEO;
 224
 225         add_timer(&zf_timer);
 226
 227         /* start watchdog timer */
 228         ctrl_reg = zf_get_control();
 229         ctrl_reg |= (ENABLE_WD1|zf_action);
 230         zf_set_control(ctrl_reg);
 231         spin_unlock_irqrestore(&zf_port_lock, flags);
 232
 233         printk(KERN_INFO PFX ": Watchdog timer is now enabled\n");
 234 }
 235
 236
 237 static void zf_ping(unsigned long data)
 238 {
 239         unsigned int ctrl_reg = 0;
 240         unsigned long flags;
 241
 242         zf_writeb(COUNTER_2, 0xff);
 243
 244         if(time_before(jiffies, next_heartbeat)){
 245
 246                 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
 247
 248                 /*
 249                  * reset event is activated by transition from 0 to 1 on
 250                  * RESET_WD1 bit and we assume that it is already zero...
 251                  */
 252
 253                 spin_lock_irqsave(&zf_port_lock, flags);
 254                 ctrl_reg = zf_get_control();
 255                 ctrl_reg |= RESET_WD1;
 256                 zf_set_control(ctrl_reg);
 257
 258                 /* ...and nothing changes until here */
 259                 ctrl_reg &= ~(RESET_WD1);
 260                 zf_set_control(ctrl_reg);
 261                 spin_unlock_irqrestore(&zf_port_lock, flags);
 262
 263                 zf_timer.expires = jiffies + ZF_HW_TIMEO;
 264                 add_timer(&zf_timer);
 265         }else{
 266                 printk(KERN_CRIT PFX ": I will reset your machine\n");
 267         }
 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                 /*
 277                  * no need to check for close confirmation
 278                  * no way to disable watchdog ;)
 279                  */
 280                 if (!nowayout) {
 281                         size_t ofs;
 282
 283                         /*
 284                          * note: just in case someone wrote the magic character
 285                          * five months ago...
 286                          */
 287                         zf_expect_close = 0;
 288
 289                         /* now scan */
 290                         for (ofs = 0; ofs != count; ofs++){
 291                                 char c;
 292                                 if (get_user(c, buf + ofs))
 293                                         return -EFAULT;
 294                                 if (c == 'V'){
 295                                         zf_expect_close = 42;
 296                                         dprintk("zf_expect_close = 42\n");
 297                                 }
 298                         }
 299                 }
 300
 301                 /*
 302                  * Well, anyhow someone wrote to us,
 303                  * we should return that favour
 304                  */
 305                 next_heartbeat = jiffies + ZF_USER_TIMEO;
 306                 dprintk("user ping at %ld\n", jiffies);
 307
 308         }
 309
 310         return count;
 311 }
 312
 313 static int zf_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 314         unsigned long arg)
 315 {
 316         void __user *argp = (void __user *)arg;
 317         int __user *p = argp;
 318         switch(cmd){
 319                 case WDIOC_GETSUPPORT:
 320                         if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 321                                 return -EFAULT;
 322                         break;
 323
 324                 case WDIOC_GETSTATUS:
 325                         return put_user(0, p);
 326
 327                 case WDIOC_KEEPALIVE:
 328                         zf_ping(0);
 329                         break;
 330
 331                 default:
 332                         return -ENOIOCTLCMD;
 333         }
 334
 335         return 0;
 336 }
 337
 338 static int zf_open(struct inode *inode, struct file *file)
 339 {
 340         spin_lock(&zf_lock);
 341         if(test_and_set_bit(0, &zf_is_open)) {
 342                 spin_unlock(&zf_lock);
 343                 return -EBUSY;
 344         }
 345
 346         if (nowayout)
 347                 __module_get(THIS_MODULE);
 348
 349         spin_unlock(&zf_lock);
 350
 351         zf_timer_on();
 352
 353         return nonseekable_open(inode, file);
 354 }
 355
 356 static int zf_close(struct inode *inode, struct file *file)
 357 {
 358         if(zf_expect_close == 42){
 359                 zf_timer_off();
 360         } else {
 361                 del_timer(&zf_timer);
 362                 printk(KERN_ERR PFX ": device file closed unexpectedly. Will not stop the WDT!\n");
 363         }
 364
 365         spin_lock(&zf_lock);
 366         clear_bit(0, &zf_is_open);
 367         spin_unlock(&zf_lock);
 368
 369         zf_expect_close = 0;
 370
 371         return 0;
 372 }
 373
 374 /*
 375  * Notifier for system down
 376  */
 377
 378 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 379                                                                 void *unused)
 380 {
 381         if(code == SYS_DOWN || code == SYS_HALT){
 382                 zf_timer_off();
 383         }
 384
 385         return NOTIFY_DONE;
 386 }
 387
 388
 389
 390
 391 static const struct file_operations zf_fops = {
 392         .owner          = THIS_MODULE,
 393         .llseek         = no_llseek,
 394         .write          = zf_write,
 395         .ioctl          = zf_ioctl,
 396         .open           = zf_open,
 397         .release        = zf_close,
 398 };
 399
 400 static struct miscdevice zf_miscdev = {
 401         .minor = WATCHDOG_MINOR,
 402         .name = "watchdog",
 403         .fops = &zf_fops,
 404 };
 405
 406
 407 /*
 408  * The device needs to learn about soft shutdowns in order to
 409  * turn the timebomb registers off.
 410  */
 411 static struct notifier_block zf_notifier = {
 412         .notifier_call = zf_notify_sys,
 413 };
 414
 415 static void __init zf_show_action(int act)
 416 {
 417         char *str[] = { "RESET", "SMI", "NMI", "SCI" };
 418
 419         printk(KERN_INFO PFX ": Watchdog using action = %s\n", str[act]);
 420 }
 421
 422 static int __init zf_init(void)
 423 {
 424         int ret;
 425
 426         printk(KERN_INFO PFX ": MachZ ZF-Logic Watchdog driver initializing.\n");
 427
 428         ret = zf_get_ZFL_version();
 429         printk("%#x\n", ret);
 430         if((!ret) || (ret != 0xffff)){
 431                 printk(KERN_WARNING PFX ": no ZF-Logic found\n");
 432                 return -ENODEV;
 433         }
 434
 435         if((action <= 3) && (action >= 0)){
 436                 zf_action = zf_action>>action;
 437         } else
 438                 action = 0;
 439
 440         zf_show_action(action);
 441
 442         spin_lock_init(&zf_lock);
 443         spin_lock_init(&zf_port_lock);
 444
 445         ret = misc_register(&zf_miscdev);
 446         if (ret){
 447                 printk(KERN_ERR "can't misc_register on minor=%d\n",
 448                                                         WATCHDOG_MINOR);
 449                 goto out;
 450         }
 451
 452         if(!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")){
 453                 printk(KERN_ERR "cannot reserve I/O ports at %d\n",
 454                                                         ZF_IOBASE);
 455                 ret = -EBUSY;
 456                 goto no_region;
 457         }
 458
 459         ret = register_reboot_notifier(&zf_notifier);
 460         if(ret){
 461                 printk(KERN_ERR "can't register reboot notifier (err=%d)\n",
 462                                                                         ret);
 463                 goto no_reboot;
 464         }
 465
 466         zf_set_status(0);
 467         zf_set_control(0);
 468
 469         /* this is the timer that will do the hard work */
 470         init_timer(&zf_timer);
 471         zf_timer.function = zf_ping;
 472         zf_timer.data = 0;
 473
 474         return 0;
 475
 476 no_reboot:
 477         release_region(ZF_IOBASE, 3);
 478 no_region:
 479         misc_deregister(&zf_miscdev);
 480 out:
 481         return ret;
 482 }
 483
 484
 485 static void __exit zf_exit(void)
 486 {
 487         zf_timer_off();
 488
 489         misc_deregister(&zf_miscdev);
 490         unregister_reboot_notifier(&zf_notifier);
 491         release_region(ZF_IOBASE, 3);
 492 }
 493
 494 module_init(zf_init);
 495 module_exit(zf_exit);