LXR linux/drivers/watchdog/w83877f

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      W83877F Computer Watchdog Timer driver
   4 *
   5 *      Based on acquirewdt.c by Alan Cox,
   6 *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
   7 *
   8 *      The authors do NOT admit liability nor provide warranty for
   9 *      any of this software. This material is provided "AS-IS" in
  10 *      the hope that it may be useful for others.
  11 *
  12 *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
  13 *
  14 *           4/19 - 2001      [Initial revision]
  15 *           9/27 - 2001      Added spinlocking
  16 *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
  17 *                            Eliminate fop_read
  18 *                            Eliminate extra spin_unlock
  19 *                            Added KERN_* tags to printks
  20 *                            add CONFIG_WATCHDOG_NOWAYOUT support
  21 *                            fix possible wdt_is_open race
  22 *                            changed watchdog_info to correctly reflect what
  23 *                            the driver offers
  24 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
  25 *                            WDIOC_SETTIMEOUT,
  26 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
  27 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  28 *                            added extra printk's for startup problems
  29 *                            use module_param
  30 *                            made timeout (the emulated heartbeat) a
  31 *                            module_param
  32 *                            made the keepalive ping an internal subroutine
  33 *
  34 *  This WDT driver is different from most other Linux WDT
  35 *  drivers in that the driver will ping the watchdog by itself,
  36 *  because this particular WDT has a very short timeout (1.6
  37 *  seconds) and it would be insane to count on any userspace
  38 *  daemon always getting scheduled within that time frame.
  39 */
  40
  41#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  42
  43#include <linux/module.h>
  44#include <linux/moduleparam.h>
  45#include <linux/types.h>
  46#include <linux/timer.h>
  47#include <linux/jiffies.h>
  48#include <linux/miscdevice.h>
  49#include <linux/watchdog.h>
  50#include <linux/fs.h>
  51#include <linux/ioport.h>
  52#include <linux/notifier.h>
  53#include <linux/reboot.h>
  54#include <linux/init.h>
  55#include <linux/io.h>
  56#include <linux/uaccess.h>
  57
  58#define OUR_NAME "w83877f_wdt"
  59
  60#define ENABLE_W83877F_PORT 0x3F0
  61#define ENABLE_W83877F 0x87
  62#define DISABLE_W83877F 0xAA
  63#define WDT_PING 0x443
  64#define WDT_REGISTER 0x14
  65#define WDT_ENABLE 0x9C
  66#define WDT_DISABLE 0x8C
  67
  68/*
  69 * The W83877F seems to be fixed at 1.6s timeout (at least on the
  70 * EMACS PC-104 board I'm using). If we reset the watchdog every
  71 * ~250ms we should be safe.  */
  72
  73#define WDT_INTERVAL (HZ/4+1)
  74
  75/*
  76 * We must not require too good response from the userspace daemon.
  77 * Here we require the userspace daemon to send us a heartbeat
  78 * char to /dev/watchdog every 30 seconds.
  79 */
  80
  81#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
  82/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  83static int timeout = WATCHDOG_TIMEOUT;
  84module_param(timeout, int, 0);
  85MODULE_PARM_DESC(timeout,
  86        "Watchdog timeout in seconds. (1<=timeout<=3600, default="
  87                                __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
  88
  89
  90static bool nowayout = WATCHDOG_NOWAYOUT;
  91module_param(nowayout, bool, 0);
  92MODULE_PARM_DESC(nowayout,
  93                "Watchdog cannot be stopped once started (default="
  94                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  95
  96static void wdt_timer_ping(struct timer_list *);
  97static DEFINE_TIMER(timer, wdt_timer_ping);
  98static unsigned long next_heartbeat;
  99static unsigned long wdt_is_open;
 100static char wdt_expect_close;
 101static DEFINE_SPINLOCK(wdt_spinlock);
 102
 103/*
 104 *      Whack the dog
 105 */
 106
 107static void wdt_timer_ping(struct timer_list *unused)
 108{
 109        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 110         * we agree to ping the WDT
 111         */
 112        if (time_before(jiffies, next_heartbeat)) {
 113                /* Ping the WDT */
 114                spin_lock(&wdt_spinlock);
 115
 116                /* Ping the WDT by reading from WDT_PING */
 117                inb_p(WDT_PING);
 118
 119                /* Re-set the timer interval */
 120                mod_timer(&timer, jiffies + WDT_INTERVAL);
 121
 122                spin_unlock(&wdt_spinlock);
 123
 124        } else
 125                pr_warn("Heartbeat lost! Will not ping the watchdog\n");
 126}
 127
 128/*
 129 * Utility routines
 130 */
 131
 132static void wdt_change(int writeval)
 133{
 134        unsigned long flags;
 135        spin_lock_irqsave(&wdt_spinlock, flags);
 136
 137        /* buy some time */
 138        inb_p(WDT_PING);
 139
 140        /* make W83877F available */
 141        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 142        outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
 143
 144        /* enable watchdog */
 145        outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
 146        outb_p(writeval,        ENABLE_W83877F_PORT+1);
 147
 148        /* lock the W8387FF away */
 149        outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
 150
 151        spin_unlock_irqrestore(&wdt_spinlock, flags);
 152}
 153
 154static void wdt_startup(void)
 155{
 156        next_heartbeat = jiffies + (timeout * HZ);
 157
 158        /* Start the timer */
 159        mod_timer(&timer, jiffies + WDT_INTERVAL);
 160
 161        wdt_change(WDT_ENABLE);
 162
 163        pr_info("Watchdog timer is now enabled\n");
 164}
 165
 166static void wdt_turnoff(void)
 167{
 168        /* Stop the timer */
 169        del_timer_sync(&timer);
 170
 171        wdt_change(WDT_DISABLE);
 172
 173        pr_info("Watchdog timer is now disabled...\n");
 174}
 175
 176static void wdt_keepalive(void)
 177{
 178        /* user land ping */
 179        next_heartbeat = jiffies + (timeout * HZ);
 180}
 181
 182/*
 183 * /dev/watchdog handling
 184 */
 185
 186static ssize_t fop_write(struct file *file, const char __user *buf,
 187                                                size_t count, loff_t *ppos)
 188{
 189        /* See if we got the magic character 'V' and reload the timer */
 190        if (count) {
 191                if (!nowayout) {
 192                        size_t ofs;
 193
 194                        /* note: just in case someone wrote the magic
 195                           character five months ago... */
 196                        wdt_expect_close = 0;
 197
 198                        /* scan to see whether or not we got the
 199                           magic character */
 200                        for (ofs = 0; ofs != count; ofs++) {
 201                                char c;
 202                                if (get_user(c, buf + ofs))
 203                                        return -EFAULT;
 204                                if (c == 'V')
 205                                        wdt_expect_close = 42;
 206                        }
 207                }
 208
 209                /* someone wrote to us, we should restart timer */
 210                wdt_keepalive();
 211        }
 212        return count;
 213}
 214
 215static int fop_open(struct inode *inode, struct file *file)
 216{
 217        /* Just in case we're already talking to someone... */
 218        if (test_and_set_bit(0, &wdt_is_open))
 219                return -EBUSY;
 220
 221        /* Good, fire up the show */
 222        wdt_startup();
 223        return stream_open(inode, file);
 224}
 225
 226static int fop_close(struct inode *inode, struct file *file)
 227{
 228        if (wdt_expect_close == 42)
 229                wdt_turnoff();
 230        else {
 231                del_timer(&timer);
 232                pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
 233        }
 234        clear_bit(0, &wdt_is_open);
 235        wdt_expect_close = 0;
 236        return 0;
 237}
 238
 239static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 240{
 241        void __user *argp = (void __user *)arg;
 242        int __user *p = argp;
 243        static const struct watchdog_info ident = {
 244                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
 245                                                        | WDIOF_MAGICCLOSE,
 246                .firmware_version = 1,
 247                .identity = "W83877F",
 248        };
 249
 250        switch (cmd) {
 251        case WDIOC_GETSUPPORT:
 252                return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
 253        case WDIOC_GETSTATUS:
 254        case WDIOC_GETBOOTSTATUS:
 255                return put_user(0, p);
 256        case WDIOC_SETOPTIONS:
 257        {
 258                int new_options, retval = -EINVAL;
 259
 260                if (get_user(new_options, p))
 261                        return -EFAULT;
 262
 263                if (new_options & WDIOS_DISABLECARD) {
 264                        wdt_turnoff();
 265                        retval = 0;
 266                }
 267
 268                if (new_options & WDIOS_ENABLECARD) {
 269                        wdt_startup();
 270                        retval = 0;
 271                }
 272
 273                return retval;
 274        }
 275        case WDIOC_KEEPALIVE:
 276                wdt_keepalive();
 277                return 0;
 278        case WDIOC_SETTIMEOUT:
 279        {
 280                int new_timeout;
 281
 282                if (get_user(new_timeout, p))
 283                        return -EFAULT;
 284
 285                /* arbitrary upper limit */
 286                if (new_timeout < 1 || new_timeout > 3600)
 287                        return -EINVAL;
 288
 289                timeout = new_timeout;
 290                wdt_keepalive();
 291        }
 292                fallthrough;
 293        case WDIOC_GETTIMEOUT:
 294                return put_user(timeout, p);
 295        default:
 296                return -ENOTTY;
 297        }
 298}
 299
 300static const struct file_operations wdt_fops = {
 301        .owner          = THIS_MODULE,
 302        .llseek         = no_llseek,
 303        .write          = fop_write,
 304        .open           = fop_open,
 305        .release        = fop_close,
 306        .unlocked_ioctl = fop_ioctl,
 307        .compat_ioctl   = compat_ptr_ioctl,
 308};
 309
 310static struct miscdevice wdt_miscdev = {
 311        .minor  = WATCHDOG_MINOR,
 312        .name   = "watchdog",
 313        .fops   = &wdt_fops,
 314};
 315
 316/*
 317 *      Notifier for system down
 318 */
 319
 320static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 321        void *unused)
 322{
 323        if (code == SYS_DOWN || code == SYS_HALT)
 324                wdt_turnoff();
 325        return NOTIFY_DONE;
 326}
 327
 328/*
 329 *      The WDT needs to learn about soft shutdowns in order to
 330 *      turn the timebomb registers off.
 331 */
 332
 333static struct notifier_block wdt_notifier = {
 334        .notifier_call = wdt_notify_sys,
 335};
 336
 337static void __exit w83877f_wdt_unload(void)
 338{
 339        wdt_turnoff();
 340
 341        /* Deregister */
 342        misc_deregister(&wdt_miscdev);
 343
 344        unregister_reboot_notifier(&wdt_notifier);
 345        release_region(WDT_PING, 1);
 346        release_region(ENABLE_W83877F_PORT, 2);
 347}
 348
 349static int __init w83877f_wdt_init(void)
 350{
 351        int rc = -EBUSY;
 352
 353        if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
 354                timeout = WATCHDOG_TIMEOUT;
 355                pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
 356                        timeout);
 357        }
 358
 359        if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
 360                pr_err("I/O address 0x%04x already in use\n",
 361                       ENABLE_W83877F_PORT);
 362                rc = -EIO;
 363                goto err_out;
 364        }
 365
 366        if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
 367                pr_err("I/O address 0x%04x already in use\n", WDT_PING);
 368                rc = -EIO;
 369                goto err_out_region1;
 370        }
 371
 372        rc = register_reboot_notifier(&wdt_notifier);
 373        if (rc) {
 374                pr_err("cannot register reboot notifier (err=%d)\n", rc);
 375                goto err_out_region2;
 376        }
 377
 378        rc = misc_register(&wdt_miscdev);
 379        if (rc) {
 380                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 381                       wdt_miscdev.minor, rc);
 382                goto err_out_reboot;
 383        }
 384
 385        pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
 386                timeout, nowayout);
 387
 388        return 0;
 389
 390err_out_reboot:
 391        unregister_reboot_notifier(&wdt_notifier);
 392err_out_region2:
 393        release_region(WDT_PING, 1);
 394err_out_region1:
 395        release_region(ENABLE_W83877F_PORT, 2);
 396err_out:
 397        return rc;
 398}
 399
 400module_init(w83877f_wdt_init);
 401module_exit(w83877f_wdt_unload);
 402
 403MODULE_AUTHOR("Scott and Bill Jennings");
 404MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
 405MODULE_LICENSE("GPL");
 406