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=" __MODULE_STRING(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 void zf_ping(unsigned long data);
 122
 123 static int zf_action = GEN_RESET;
 124 static unsigned long zf_is_open;
 125 static char zf_expect_close;
 126 static spinlock_t zf_lock;
 127 static spinlock_t zf_port_lock;
 128 static DEFINE_TIMER(zf_timer, zf_ping, 0, 0);
 129 static unsigned long next_heartbeat = 0;
 130
 131
 132 /* timeout for user land heart beat (10 seconds) */
 133 #define ZF_USER_TIMEO (HZ*10)
 134
 135 /* timeout for hardware watchdog (~500ms) */
 136 #define ZF_HW_TIMEO (HZ/2)
 137
 138 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 139 #define ZF_CTIMEOUT 0xffff
 140
 141 #ifndef ZF_DEBUG
 142 #       define dprintk(format, args...)
 143 #else
 144 #       define dprintk(format, args...) printk(KERN_DEBUG PFX ":%s:%d: " format, __FUNCTION__, __LINE__ , ## args)
 145 #endif
 146
 147
 148 static inline void zf_set_status(unsigned char new)
 149 {
 150         zf_writeb(STATUS, new);
 151 }
 152
 153
 154 /* CONTROL register functions */
 155
 156 static inline unsigned short zf_get_control(void)
 157 {
 158         return zf_readw(CONTROL);
 159 }
 160
 161 static inline void zf_set_control(unsigned short new)
 162 {
 163         zf_writew(CONTROL, new);
 164 }
 165
 166
 167 /* WD#? counter functions */
 168 /*
 169  *      Just set counter value
 170  */
 171
 172 static inline void zf_set_timer(unsigned short new, unsigned char n)
 173 {
 174         switch(n){
 175                 case WD1:
 176                         zf_writew(COUNTER_1, new);
 177                 case WD2:
 178                         zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 179                 default:
 180                         return;
 181         }
 182 }
 183
 184 /*
 185  * stop hardware timer
 186  */
 187 static void zf_timer_off(void)
 188 {
 189         unsigned int ctrl_reg = 0;
 190         unsigned long flags;
 191
 192         /* stop internal ping */
 193         del_timer_sync(&zf_timer);
 194
 195         spin_lock_irqsave(&zf_port_lock, flags);
 196         /* stop watchdog timer */
 197         ctrl_reg = zf_get_control();
 198         ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 199         ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 200         zf_set_control(ctrl_reg);
 201         spin_unlock_irqrestore(&zf_port_lock, flags);
 202
 203         printk(KERN_INFO PFX ": Watchdog timer is now disabled\n");
 204 }
 205
 206
 207 /*
 208  * start hardware timer
 209  */
 210 static void zf_timer_on(void)
 211 {
 212         unsigned int ctrl_reg = 0;
 213         unsigned long flags;
 214
 215         spin_lock_irqsave(&zf_port_lock, flags);
 216
 217         zf_writeb(PULSE_LEN, 0xff);
 218
 219         zf_set_timer(ZF_CTIMEOUT, WD1);
 220
 221         /* user land ping */
 222         next_heartbeat = jiffies + ZF_USER_TIMEO;
 223
 224         /* start the timer for internal ping */
 225         mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 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                 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 264         }else{
 265                 printk(KERN_CRIT PFX ": I will reset your machine\n");
 266         }
 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                 /*
 276                  * no need to check for close confirmation
 277                  * no way to disable watchdog ;)
 278                  */
 279                 if (!nowayout) {
 280                         size_t ofs;
 281
 282                         /*
 283                          * note: just in case someone wrote the magic character
 284                          * five months ago...
 285                          */
 286                         zf_expect_close = 0;
 287
 288                         /* now scan */
 289                         for (ofs = 0; ofs != count; ofs++){
 290                                 char c;
 291                                 if (get_user(c, buf + ofs))
 292                                         return -EFAULT;
 293                                 if (c == 'V'){
 294                                         zf_expect_close = 42;
 295                                         dprintk("zf_expect_close = 42\n");
 296                                 }
 297                         }
 298                 }
 299
 300                 /*
 301                  * Well, anyhow someone wrote to us,
 302                  * we should return that favour
 303                  */
 304                 next_heartbeat = jiffies + ZF_USER_TIMEO;
 305                 dprintk("user ping at %ld\n", jiffies);
 306
 307         }
 308
 309         return count;
 310 }
 311
 312 static int zf_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 313         unsigned long arg)
 314 {
 315         void __user *argp = (void __user *)arg;
 316         int __user *p = argp;
 317         switch(cmd){
 318                 case WDIOC_GETSUPPORT:
 319                         if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 320                                 return -EFAULT;
 321                         break;
 322
 323                 case WDIOC_GETSTATUS:
 324                         return put_user(0, p);
 325
 326                 case WDIOC_KEEPALIVE:
 327                         zf_ping(NULL);
 328                         break;
 329
 330                 default:
 331                         return -ENOTTY;
 332         }
 333
 334         return 0;
 335 }
 336
 337 static int zf_open(struct inode *inode, struct file *file)
 338 {
 339         spin_lock(&zf_lock);
 340         if(test_and_set_bit(0, &zf_is_open)) {
 341                 spin_unlock(&zf_lock);
 342                 return -EBUSY;
 343         }
 344
 345         if (nowayout)
 346                 __module_get(THIS_MODULE);
 347
 348         spin_unlock(&zf_lock);
 349
 350         zf_timer_on();
 351
 352         return nonseekable_open(inode, file);
 353 }
 354
 355 static int zf_close(struct inode *inode, struct file *file)
 356 {
 357         if(zf_expect_close == 42){
 358                 zf_timer_off();
 359         } else {
 360                 del_timer(&zf_timer);
 361                 printk(KERN_ERR PFX ": device file closed unexpectedly. Will not stop the WDT!\n");
 362         }
 363
 364         spin_lock(&zf_lock);
 365         clear_bit(0, &zf_is_open);
 366         spin_unlock(&zf_lock);
 367
 368         zf_expect_close = 0;
 369
 370         return 0;
 371 }
 372
 373 /*
 374  * Notifier for system down
 375  */
 376
 377 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 378                                                                 void *unused)
 379 {
 380         if(code == SYS_DOWN || code == SYS_HALT){
 381                 zf_timer_off();
 382         }
 383
 384         return NOTIFY_DONE;
 385 }
 386
 387
 388
 389
 390 static const struct file_operations zf_fops = {
 391         .owner          = THIS_MODULE,
 392         .llseek         = no_llseek,
 393         .write          = zf_write,
 394         .ioctl          = zf_ioctl,
 395         .open           = zf_open,
 396         .release        = zf_close,
 397 };
 398
 399 static struct miscdevice zf_miscdev = {
 400         .minor = WATCHDOG_MINOR,
 401         .name = "watchdog",
 402         .fops = &zf_fops,
 403 };
 404
 405
 406 /*
 407  * The device needs to learn about soft shutdowns in order to
 408  * turn the timebomb registers off.
 409  */
 410 static struct notifier_block zf_notifier = {
 411         .notifier_call = zf_notify_sys,
 412 };
 413
 414 static void __init zf_show_action(int act)
 415 {
 416         char *str[] = { "RESET", "SMI", "NMI", "SCI" };
 417
 418         printk(KERN_INFO PFX ": Watchdog using action = %s\n", str[act]);
 419 }
 420
 421 static int __init zf_init(void)
 422 {
 423         int ret;
 424
 425         printk(KERN_INFO PFX ": MachZ ZF-Logic Watchdog driver initializing.\n");
 426
 427         ret = zf_get_ZFL_version();
 428         if ((!ret) || (ret == 0xffff)) {
 429                 printk(KERN_WARNING PFX ": no ZF-Logic found\n");
 430                 return -ENODEV;
 431         }
 432
 433         if((action <= 3) && (action >= 0)){
 434                 zf_action = zf_action>>action;
 435         } else
 436                 action = 0;
 437
 438         zf_show_action(action);
 439
 440         spin_lock_init(&zf_lock);
 441         spin_lock_init(&zf_port_lock);
 442
 443         ret = misc_register(&zf_miscdev);
 444         if (ret){
 445                 printk(KERN_ERR "can't misc_register on minor=%d\n",
 446                                                         WATCHDOG_MINOR);
 447                 goto out;
 448         }
 449
 450         if(!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")){
 451                 printk(KERN_ERR "cannot reserve I/O ports at %d\n",
 452                                                         ZF_IOBASE);
 453                 ret = -EBUSY;
 454                 goto no_region;
 455         }
 456
 457         ret = register_reboot_notifier(&zf_notifier);
 458         if(ret){
 459                 printk(KERN_ERR "can't register reboot notifier (err=%d)\n",
 460                                                                         ret);
 461                 goto no_reboot;
 462         }
 463
 464         zf_set_status(0);
 465         zf_set_control(0);
 466
 467         return 0;
 468
 469 no_reboot:
 470         release_region(ZF_IOBASE, 3);
 471 no_region:
 472         misc_deregister(&zf_miscdev);
 473 out:
 474         return ret;
 475 }
 476
 477
 478 static void __exit zf_exit(void)
 479 {
 480         zf_timer_off();
 481
 482         misc_deregister(&zf_miscdev);
 483         unregister_reboot_notifier(&zf_notifier);
 484         release_region(ZF_IOBASE, 3);
 485 }
 486
 487 module_init(zf_init);
 488 module_exit(zf_exit);