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");
  95
  96static bool nowayout = WATCHDOG_NOWAYOUT;
  97module_param(nowayout, bool, 0);
  98MODULE_PARM_DESC(nowayout,
  99                "Watchdog cannot be stopped once started (default="
 100                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 101
 102#define PFX "machzwd"
 103
 104static const struct watchdog_info zf_info = {
 105        .options                = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 106        .firmware_version       = 1,
 107        .identity               = "ZF-Logic watchdog",
 108};
 109
 110
 111/*
 112 * action refers to action taken when watchdog resets
 113 * 0 = GEN_RESET
 114 * 1 = GEN_SMI
 115 * 2 = GEN_NMI
 116 * 3 = GEN_SCI
 117 * defaults to GEN_RESET (0)
 118 */
 119static int action;
 120module_param(action, int, 0);
 121MODULE_PARM_DESC(action, "after watchdog resets, generate: "
 122                                "0 = RESET(*)  1 = SMI  2 = NMI  3 = SCI");
 123
 124static void zf_ping(struct timer_list *unused);
 125
 126static int zf_action = GEN_RESET;
 127static unsigned long zf_is_open;
 128static char zf_expect_close;
 129static DEFINE_SPINLOCK(zf_port_lock);
 130static DEFINE_TIMER(zf_timer, zf_ping);
 131static unsigned long next_heartbeat;
 132
 133
 134/* timeout for user land heart beat (10 seconds) */
 135#define ZF_USER_TIMEO (HZ*10)
 136
 137/* timeout for hardware watchdog (~500ms) */
 138#define ZF_HW_TIMEO (HZ/2)
 139
 140/* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
 141#define ZF_CTIMEOUT 0xffff
 142
 143#ifndef ZF_DEBUG
 144#define dprintk(format, args...)
 145#else
 146#define dprintk(format, args...)                                        \
 147        pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
 148#endif
 149
 150
 151static inline void zf_set_status(unsigned char new)
 152{
 153        zf_writeb(STATUS, new);
 154}
 155
 156
 157/* CONTROL register functions */
 158
 159static inline unsigned short zf_get_control(void)
 160{
 161        return zf_readw(CONTROL);
 162}
 163
 164static inline void zf_set_control(unsigned short new)
 165{
 166        zf_writew(CONTROL, new);
 167}
 168
 169
 170/* WD#? counter functions */
 171/*
 172 *      Just set counter value
 173 */
 174
 175static inline void zf_set_timer(unsigned short new, unsigned char n)
 176{
 177        switch (n) {
 178        case WD1:
 179                zf_writew(COUNTER_1, new);
 180        case WD2:
 181                zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
 182        default:
 183                return;
 184        }
 185}
 186
 187/*
 188 * stop hardware timer
 189 */
 190static void zf_timer_off(void)
 191{
 192        unsigned int ctrl_reg = 0;
 193        unsigned long flags;
 194
 195        /* stop internal ping */
 196        del_timer_sync(&zf_timer);
 197
 198        spin_lock_irqsave(&zf_port_lock, flags);
 199        /* stop watchdog timer */
 200        ctrl_reg = zf_get_control();
 201        ctrl_reg |= (ENABLE_WD1|ENABLE_WD2);    /* disable wd1 and wd2 */
 202        ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
 203        zf_set_control(ctrl_reg);
 204        spin_unlock_irqrestore(&zf_port_lock, flags);
 205
 206        pr_info("Watchdog timer is now disabled\n");
 207}
 208
 209
 210/*
 211 * start hardware timer
 212 */
 213static void zf_timer_on(void)
 214{
 215        unsigned int ctrl_reg = 0;
 216        unsigned long flags;
 217
 218        spin_lock_irqsave(&zf_port_lock, flags);
 219
 220        zf_writeb(PULSE_LEN, 0xff);
 221
 222        zf_set_timer(ZF_CTIMEOUT, WD1);
 223
 224        /* user land ping */
 225        next_heartbeat = jiffies + ZF_USER_TIMEO;
 226
 227        /* start the timer for internal ping */
 228        mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 229
 230        /* start watchdog timer */
 231        ctrl_reg = zf_get_control();
 232        ctrl_reg |= (ENABLE_WD1|zf_action);
 233        zf_set_control(ctrl_reg);
 234        spin_unlock_irqrestore(&zf_port_lock, flags);
 235
 236        pr_info("Watchdog timer is now enabled\n");
 237}
 238
 239
 240static void zf_ping(struct timer_list *unused)
 241{
 242        unsigned int ctrl_reg = 0;
 243        unsigned long flags;
 244
 245        zf_writeb(COUNTER_2, 0xff);
 246
 247        if (time_before(jiffies, next_heartbeat)) {
 248                dprintk("time_before: %ld\n", next_heartbeat - jiffies);
 249                /*
 250                 * reset event is activated by transition from 0 to 1 on
 251                 * RESET_WD1 bit and we assume that it is already zero...
 252                 */
 253
 254                spin_lock_irqsave(&zf_port_lock, flags);
 255                ctrl_reg = zf_get_control();
 256                ctrl_reg |= RESET_WD1;
 257                zf_set_control(ctrl_reg);
 258
 259                /* ...and nothing changes until here */
 260                ctrl_reg &= ~(RESET_WD1);
 261                zf_set_control(ctrl_reg);
 262                spin_unlock_irqrestore(&zf_port_lock, flags);
 263
 264                mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
 265        } else
 266                pr_crit("I will reset your machine\n");
 267}
 268
 269static 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                 * no need to check for close confirmation
 276                 * no way to disable watchdog ;)
 277                 */
 278                if (!nowayout) {
 279                        size_t ofs;
 280                        /*
 281                         * note: just in case someone wrote the magic character
 282                         * five months ago...
 283                         */
 284                        zf_expect_close = 0;
 285
 286                        /* now scan */
 287                        for (ofs = 0; ofs != count; ofs++) {
 288                                char c;
 289                                if (get_user(c, buf + ofs))
 290                                        return -EFAULT;
 291                                if (c == 'V') {
 292                                        zf_expect_close = 42;
 293                                        dprintk("zf_expect_close = 42\n");
 294                                }
 295                        }
 296                }
 297
 298                /*
 299                 * Well, anyhow someone wrote to us,
 300                 * we should return that favour
 301                 */
 302                next_heartbeat = jiffies + ZF_USER_TIMEO;
 303                dprintk("user ping at %ld\n", jiffies);
 304        }
 305        return count;
 306}
 307
 308static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 309{
 310        void __user *argp = (void __user *)arg;
 311        int __user *p = argp;
 312        switch (cmd) {
 313        case WDIOC_GETSUPPORT:
 314                if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
 315                        return -EFAULT;
 316                break;
 317        case WDIOC_GETSTATUS:
 318        case WDIOC_GETBOOTSTATUS:
 319                return put_user(0, p);
 320        case WDIOC_KEEPALIVE:
 321                zf_ping(0);
 322                break;
 323        default:
 324                return -ENOTTY;
 325        }
 326        return 0;
 327}
 328
 329static int zf_open(struct inode *inode, struct file *file)
 330{
 331        if (test_and_set_bit(0, &zf_is_open))
 332                return -EBUSY;
 333        if (nowayout)
 334                __module_get(THIS_MODULE);
 335        zf_timer_on();
 336        return nonseekable_open(inode, file);
 337}
 338
 339static int zf_close(struct inode *inode, struct file *file)
 340{
 341        if (zf_expect_close == 42)
 342                zf_timer_off();
 343        else {
 344                del_timer(&zf_timer);
 345                pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
 346        }
 347        clear_bit(0, &zf_is_open);
 348        zf_expect_close = 0;
 349        return 0;
 350}
 351
 352/*
 353 * Notifier for system down
 354 */
 355
 356static int zf_notify_sys(struct notifier_block *this, unsigned long code,
 357                                                                void *unused)
 358{
 359        if (code == SYS_DOWN || code == SYS_HALT)
 360                zf_timer_off();
 361        return NOTIFY_DONE;
 362}
 363
 364static const struct file_operations zf_fops = {
 365        .owner          = THIS_MODULE,
 366        .llseek         = no_llseek,
 367        .write          = zf_write,
 368        .unlocked_ioctl = zf_ioctl,
 369        .open           = zf_open,
 370        .release        = zf_close,
 371};
 372
 373static struct miscdevice zf_miscdev = {
 374        .minor = WATCHDOG_MINOR,
 375        .name = "watchdog",
 376        .fops = &zf_fops,
 377};
 378
 379
 380/*
 381 * The device needs to learn about soft shutdowns in order to
 382 * turn the timebomb registers off.
 383 */
 384static struct notifier_block zf_notifier = {
 385        .notifier_call = zf_notify_sys,
 386};
 387
 388static void __init zf_show_action(int act)
 389{
 390        static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
 391
 392        pr_info("Watchdog using action = %s\n", str[act]);
 393}
 394
 395static int __init zf_init(void)
 396{
 397        int ret;
 398
 399        pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
 400
 401        ret = zf_get_ZFL_version();
 402        if (!ret || ret == 0xffff) {
 403                pr_warn("no ZF-Logic found\n");
 404                return -ENODEV;
 405        }
 406
 407        if (action <= 3 && action >= 0)
 408                zf_action = zf_action >> action;
 409        else
 410                action = 0;
 411
 412        zf_show_action(action);
 413
 414        if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
 415                pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
 416                ret = -EBUSY;
 417                goto no_region;
 418        }
 419
 420        ret = register_reboot_notifier(&zf_notifier);
 421        if (ret) {
 422                pr_err("can't register reboot notifier (err=%d)\n", ret);
 423                goto no_reboot;
 424        }
 425
 426        ret = misc_register(&zf_miscdev);
 427        if (ret) {
 428                pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
 429                goto no_misc;
 430        }
 431
 432        zf_set_status(0);
 433        zf_set_control(0);
 434
 435        return 0;
 436
 437no_misc:
 438        unregister_reboot_notifier(&zf_notifier);
 439no_reboot:
 440        release_region(ZF_IOBASE, 3);
 441no_region:
 442        return ret;
 443}
 444
 445
 446static void __exit zf_exit(void)
 447{
 448        zf_timer_off();
 449
 450        misc_deregister(&zf_miscdev);
 451        unregister_reboot_notifier(&zf_notifier);
 452        release_region(ZF_IOBASE, 3);
 453}
 454
 455module_init(zf_init);
 456module_exit(zf_exit);
 457