linux/drivers/watchdog/machzwd.c
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   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
  85static unsigned short zf_readw(unsigned char port)
  86{
  87        outb(port, INDEX);
  88        return inw(DATA_W);
  89}
  90
  91
  92MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
  93MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
  94MODULE_LICENSE("GPL");
  95MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  96
  97static bool nowayout = WATCHDOG_NOWAYOUT;
  98module_param(nowayout, bool, 0);
  99MODULE_PARM_DESC(nowayout,
 100                "Watchdog cannot be stopped once started (default="
 101                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 102
 103#define PFX "machzwd"
 104
 105static 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 */
 120static int action;
 121module_param(action, int, 0);
 122MODULE_PARM_DESC(action, "after watchdog resets, generate: "
 123                                "0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 124
 125static void zf_ping(unsigned long data);
 126
 127static int zf_action = GEN_RESET;
 128static unsigned long zf_is_open;
 129static char zf_expect_close;
 130static DEFINE_SPINLOCK(zf_port_lock);
 131static DEFINE_TIMER(zf_timer, zf_ping, 0, 0);
 132static 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
 152static inline void zf_set_status(unsigned char new)
 153{
 154        zf_writeb(STATUS, new);
 155}
 156
 157
 158/* CONTROL register functions */
 159
 160static inline unsigned short zf_get_control(void)
 161{
 162        return zf_readw(CONTROL);
 163}
 164
 165static 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
 176static 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 */
 191static 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 */
 214static 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
 241static 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
 270static 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
 309static 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
 330static 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
 340static 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
 357static 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
 365static 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
 374static 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 */
 385static struct notifier_block zf_notifier = {
 386        .notifier_call = zf_notify_sys,
 387};
 388
 389static 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
 396static 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
 438no_misc:
 439        unregister_reboot_notifier(&zf_notifier);
 440no_reboot:
 441        release_region(ZF_IOBASE, 3);
 442no_region:
 443        return ret;
 444}
 445
 446
 447static 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
 456module_init(zf_init);
 457module_exit(zf_exit);
 458
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