drivers/watchdog/machzwd.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  MachZ ZF-Logic Watchdog Timer driver for Linux
   4  *
   5  *  The author does NOT admit liability nor provide warranty for
   6  *  any of this software. This material is provided "AS-IS" in
   7  *  the hope that it may be useful for others.
   8  *
   9  *  Author: Fernando Fuganti <fuganti@conectiva.com.br>
  10  *
  11  *  Based on sbc60xxwdt.c by Jakob Oestergaard
  12  *
  13  *  We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
  14  *  following periods:
  15  *      wd#1 - 2 seconds;
  16  *      wd#2 - 7.2 ms;
  17  *  After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
  18  *  a system RESET and it starts wd#2 that unconditionally will RESET
  19  *  the system when the counter reaches zero.
  20  *
  21  *  14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
  22  *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
  23  */
  24
  25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/module.h>
  28 #include <linux/moduleparam.h>
  29 #include <linux/types.h>
  30 #include <linux/timer.h>
  31 #include <linux/jiffies.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/watchdog.h>
  34 #include <linux/fs.h>
  35 #include <linux/ioport.h>
  36 #include <linux/notifier.h>
  37 #include <linux/reboot.h>
  38 #include <linux/init.h>
  39 #include <linux/io.h>
  40 #include <linux/uaccess.h>
  41
  42
  43 /* ports */
  44 #define ZF_IOBASE       0x218
  45 #define INDEX           0x218
  46 #define DATA_B          0x219
  47 #define DATA_W          0x21A
  48 #define DATA_D          0x21A
  49
  50 /* indexes */                   /* size */
  51 #define ZFL_VERSION     0x02    /* 16   */
  52 #define CONTROL         0x10    /* 16   */
  53 #define STATUS          0x12    /* 8    */
  54 #define COUNTER_1       0x0C    /* 16   */
  55 #define COUNTER_2       0x0E    /* 8    */
  56 #define PULSE_LEN       0x0F    /* 8    */
  57
  58 /* controls */
  59 #define ENABLE_WD1      0x0001
  60 #define ENABLE_WD2      0x0002
  61 #define RESET_WD1       0x0010
  62 #define RESET_WD2       0x0020
  63 #define GEN_SCI         0x0100
  64 #define GEN_NMI         0x0200
  65 #define GEN_SMI         0x0400
  66 #define GEN_RESET       0x0800
  67
  68
  69 /* utilities */
  70
  71 #define WD1     0
  72 #define WD2     1
  73
  74 #define zf_writew(port, data)  { outb(port, INDEX); outw(data, DATA_W); }
  75 #define zf_writeb(port, data)  { outb(port, INDEX); outb(data, DATA_B); }
  76 #define zf_get_ZFL_version()   zf_readw(ZFL_VERSION)
  77
  78
  79 static unsigned short zf_readw(unsigned char port)
  80 {
  81         outb(port, INDEX);
  82         return inw(DATA_W);
  83 }
  84
  85
  86 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
  87 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
  88 MODULE_LICENSE("GPL");
  89
  90 static bool nowayout = WATCHDOG_NOWAYOUT;
  91 module_param(nowayout, bool, 0);
  92 MODULE_PARM_DESC(nowayout,
  93                 "Watchdog cannot be stopped once started (default="
  94                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  95
  96 #define PFX "machzwd"
  97
  98 static const struct watchdog_info zf_info = {
  99         .options                = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 100         .firmware_version       = 1,
 101         .identity               = "ZF-Logic watchdog",
 102 };
 103
 104
 105 /*
 106  * action refers to action taken when watchdog resets
 107  * 0 = GEN_RESET
 108  * 1 = GEN_SMI
 109  * 2 = GEN_NMI
 110  * 3 = GEN_SCI
 111  * defaults to GEN_RESET (0)
 112  */
 113 static int action;
 114 module_param(action, int, 0);
 115 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
 116                                 "0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 117
 118 static void zf_ping(struct timer_list *unused);
 119
 120 static int zf_action = GEN_RESET;
 121 static unsigned long zf_is_open;
 122 static char zf_expect_close;
 123 static DEFINE_SPINLOCK(zf_port_lock);
 124 static DEFINE_TIMER(zf_timer, zf_ping);
 125 static unsigned long next_heartbeat;
 126
 127
 128 /* timeout for user land heart beat (10 seconds) */
 129 #define ZF_USER_TIMEO (HZ*10)
 130
 131 /* timeout for hardware watchdog (~500ms) */
 132 #define ZF_HW_TIMEO (HZ/2)
 133
 134 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 135 #define ZF_CTIMEOUT 0xffff
 136
 137 #ifndef ZF_DEBUG
 138 #define dprintk(format, args...)
 139 #else
 140 #define dprintk(format, args...)                                        \
 141         pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
 142 #endif
 143
 144
 145 static inline void zf_set_status(unsigned char new)
 146 {
 147         zf_writeb(STATUS, new);
 148 }
 149
 150
 151 /* CONTROL register functions */
 152
 153 static inline unsigned short zf_get_control(void)
 154 {
 155         return zf_readw(CONTROL);
 156 }
 157
 158 static inline void zf_set_control(unsigned short new)
 159 {
 160         zf_writew(CONTROL, new);
 161 }
 162
 163
 164 /* WD#? counter functions */
 165 /*
 166  *      Just set counter value
 167  */
 168
 169 static inline void zf_set_timer(unsigned short new, unsigned char n)
 170 {
 171         switch (n) {
 172         case WD1:
 173                 zf_writew(COUNTER_1, new);
 174                 fallthrough;
 175         case WD2:
 176                 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 177                 fallthrough;
 178         default:
 179                 return;
 180         }
 181 }
 182
 183 /*
 184  * stop hardware timer
 185  */
 186 static void zf_timer_off(void)
 187 {
 188         unsigned int ctrl_reg = 0;
 189         unsigned long flags;
 190
 191         /* stop internal ping */
 192         del_timer_sync(&zf_timer);
 193
 194         spin_lock_irqsave(&zf_port_lock, flags);
 195         /* stop watchdog timer */
 196         ctrl_reg = zf_get_control();
 197         ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 198         ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 199         zf_set_control(ctrl_reg);
 200         spin_unlock_irqrestore(&zf_port_lock, flags);
 201
 202         pr_info("Watchdog timer is now disabled\n");
 203 }
 204
 205
 206 /*
 207  * start hardware timer
 208  */
 209 static void zf_timer_on(void)
 210 {
 211         unsigned int ctrl_reg = 0;
 212         unsigned long flags;
 213
 214         spin_lock_irqsave(&zf_port_lock, flags);
 215
 216         zf_writeb(PULSE_LEN, 0xff);
 217
 218         zf_set_timer(ZF_CTIMEOUT, WD1);
 219
 220         /* user land ping */
 221         next_heartbeat = jiffies + ZF_USER_TIMEO;
 222
 223         /* start the timer for internal ping */
 224         mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 225
 226         /* start watchdog timer */
 227         ctrl_reg = zf_get_control();
 228         ctrl_reg |= (ENABLE_WD1|zf_action);
 229         zf_set_control(ctrl_reg);
 230         spin_unlock_irqrestore(&zf_port_lock, flags);
 231
 232         pr_info("Watchdog timer is now enabled\n");
 233 }
 234
 235
 236 static void zf_ping(struct timer_list *unused)
 237 {
 238         unsigned int ctrl_reg = 0;
 239         unsigned long flags;
 240
 241         zf_writeb(COUNTER_2, 0xff);
 242
 243         if (time_before(jiffies, next_heartbeat)) {
 244                 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
 245                 /*
 246                  * reset event is activated by transition from 0 to 1 on
 247                  * RESET_WD1 bit and we assume that it is already zero...
 248                  */
 249
 250                 spin_lock_irqsave(&zf_port_lock, flags);
 251                 ctrl_reg = zf_get_control();
 252                 ctrl_reg |= RESET_WD1;
 253                 zf_set_control(ctrl_reg);
 254
 255                 /* ...and nothing changes until here */
 256                 ctrl_reg &= ~(RESET_WD1);
 257                 zf_set_control(ctrl_reg);
 258                 spin_unlock_irqrestore(&zf_port_lock, flags);
 259
 260                 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 261         } else
 262                 pr_crit("I will reset your machine\n");
 263 }
 264
 265 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
 266                                                                 loff_t *ppos)
 267 {
 268         /* See if we got the magic character */
 269         if (count) {
 270                 /*
 271                  * no need to check for close confirmation
 272                  * no way to disable watchdog ;)
 273                  */
 274                 if (!nowayout) {
 275                         size_t ofs;
 276                         /*
 277                          * note: just in case someone wrote the magic character
 278                          * five months ago...
 279                          */
 280                         zf_expect_close = 0;
 281
 282                         /* now scan */
 283                         for (ofs = 0; ofs != count; ofs++) {
 284                                 char c;
 285                                 if (get_user(c, buf + ofs))
 286                                         return -EFAULT;
 287                                 if (c == 'V') {
 288                                         zf_expect_close = 42;
 289                                         dprintk("zf_expect_close = 42\n");
 290                                 }
 291                         }
 292                 }
 293
 294                 /*
 295                  * Well, anyhow someone wrote to us,
 296                  * we should return that favour
 297                  */
 298                 next_heartbeat = jiffies + ZF_USER_TIMEO;
 299                 dprintk("user ping at %ld\n", jiffies);
 300         }
 301         return count;
 302 }
 303
 304 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 305 {
 306         void __user *argp = (void __user *)arg;
 307         int __user *p = argp;
 308         switch (cmd) {
 309         case WDIOC_GETSUPPORT:
 310                 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 311                         return -EFAULT;
 312                 break;
 313         case WDIOC_GETSTATUS:
 314         case WDIOC_GETBOOTSTATUS:
 315                 return put_user(0, p);
 316         case WDIOC_KEEPALIVE:
 317                 zf_ping(NULL);
 318                 break;
 319         default:
 320                 return -ENOTTY;
 321         }
 322         return 0;
 323 }
 324
 325 static int zf_open(struct inode *inode, struct file *file)
 326 {
 327         if (test_and_set_bit(0, &zf_is_open))
 328                 return -EBUSY;
 329         if (nowayout)
 330                 __module_get(THIS_MODULE);
 331         zf_timer_on();
 332         return stream_open(inode, file);
 333 }
 334
 335 static int zf_close(struct inode *inode, struct file *file)
 336 {
 337         if (zf_expect_close == 42)
 338                 zf_timer_off();
 339         else {
 340                 del_timer(&zf_timer);
 341                 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
 342         }
 343         clear_bit(0, &zf_is_open);
 344         zf_expect_close = 0;
 345         return 0;
 346 }
 347
 348 /*
 349  * Notifier for system down
 350  */
 351
 352 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 353                                                                 void *unused)
 354 {
 355         if (code == SYS_DOWN || code == SYS_HALT)
 356                 zf_timer_off();
 357         return NOTIFY_DONE;
 358 }
 359
 360 static const struct file_operations zf_fops = {
 361         .owner          = THIS_MODULE,
 362         .write          = zf_write,
 363         .unlocked_ioctl = zf_ioctl,
 364         .compat_ioctl   = compat_ptr_ioctl,
 365         .open           = zf_open,
 366         .release        = zf_close,
 367 };
 368
 369 static struct miscdevice zf_miscdev = {
 370         .minor = WATCHDOG_MINOR,
 371         .name = "watchdog",
 372         .fops = &zf_fops,
 373 };
 374
 375
 376 /*
 377  * The device needs to learn about soft shutdowns in order to
 378  * turn the timebomb registers off.
 379  */
 380 static struct notifier_block zf_notifier = {
 381         .notifier_call = zf_notify_sys,
 382 };
 383
 384 static void __init zf_show_action(int act)
 385 {
 386         static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
 387
 388         pr_info("Watchdog using action = %s\n", str[act]);
 389 }
 390
 391 static int __init zf_init(void)
 392 {
 393         int ret;
 394
 395         pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
 396
 397         ret = zf_get_ZFL_version();
 398         if (!ret || ret == 0xffff) {
 399                 pr_warn("no ZF-Logic found\n");
 400                 return -ENODEV;
 401         }
 402
 403         if (action <= 3 && action >= 0)
 404                 zf_action = zf_action >> action;
 405         else
 406                 action = 0;
 407
 408         zf_show_action(action);
 409
 410         if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
 411                 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
 412                 ret = -EBUSY;
 413                 goto no_region;
 414         }
 415
 416         ret = register_reboot_notifier(&zf_notifier);
 417         if (ret) {
 418                 pr_err("can't register reboot notifier (err=%d)\n", ret);
 419                 goto no_reboot;
 420         }
 421
 422         ret = misc_register(&zf_miscdev);
 423         if (ret) {
 424                 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
 425                 goto no_misc;
 426         }
 427
 428         zf_set_status(0);
 429         zf_set_control(0);
 430
 431         return 0;
 432
 433 no_misc:
 434         unregister_reboot_notifier(&zf_notifier);
 435 no_reboot:
 436         release_region(ZF_IOBASE, 3);
 437 no_region:
 438         return ret;
 439 }
 440
 441
 442 static void __exit zf_exit(void)
 443 {
 444         zf_timer_off();
 445
 446         misc_deregister(&zf_miscdev);
 447         unregister_reboot_notifier(&zf_notifier);
 448         release_region(ZF_IOBASE, 3);
 449 }
 450
 451 module_init(zf_init);
 452 module_exit(zf_exit);