LXR linux/drivers/watchdog/sbc60xxwdt.c

   1/*
   2 *      60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
   3 *
   4 *      Based on acquirewdt.c by Alan Cox.
   5 *
   6 *      This program is free software; you can redistribute it and/or
   7 *      modify it under the terms of the GNU General Public License
   8 *      as published by the Free Software Foundation; either version
   9 *      2 of the License, or (at your option) any later version.
  10 *
  11 *      The author does NOT admit liability nor provide warranty for
  12 *      any of this software. This material is provided "AS-IS" in
  13 *      the hope that it may be useful for others.
  14 *
  15 *      (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
  16 *
  17 *           12/4 - 2000      [Initial revision]
  18 *           25/4 - 2000      Added /dev/watchdog support
  19 *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1" on success
  20 *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
  21 *                            fix possible wdt_is_open race
  22 *                            add CONFIG_WATCHDOG_NOWAYOUT support
  23 *                            remove lock_kernel/unlock_kernel pairs
  24 *                            added KERN_* to printk's
  25 *                            got rid of extraneous comments
  26 *                            changed watchdog_info to correctly reflect what the driver offers
  27 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
  28 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
  29 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
  30 *                            use module_param
  31 *                            made timeout (the emulated heartbeat) a module_param
  32 *                            made the keepalive ping an internal subroutine
  33 *                            made wdt_stop and wdt_start module params
  34 *                            added extra printk's for startup problems
  35 *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
  36 *
  37 *
  38 *  This WDT driver is different from the other Linux WDT
  39 *  drivers in the following ways:
  40 *  *)  The driver will ping the watchdog by itself, because this
  41 *      particular WDT has a very short timeout (one second) and it
  42 *      would be insane to count on any userspace daemon always
  43 *      getting scheduled within that time frame.
  44 *
  45 */
  46
  47#include <linux/module.h>
  48#include <linux/moduleparam.h>
  49#include <linux/types.h>
  50#include <linux/timer.h>
  51#include <linux/jiffies.h>
  52#include <linux/miscdevice.h>
  53#include <linux/watchdog.h>
  54#include <linux/fs.h>
  55#include <linux/ioport.h>
  56#include <linux/notifier.h>
  57#include <linux/reboot.h>
  58#include <linux/init.h>
  59
  60#include <asm/io.h>
  61#include <asm/uaccess.h>
  62#include <asm/system.h>
  63
  64#define OUR_NAME "sbc60xxwdt"
  65#define PFX OUR_NAME ": "
  66
  67/*
  68 * You must set these - The driver cannot probe for the settings
  69 */
  70
  71static int wdt_stop = 0x45;
  72module_param(wdt_stop, int, 0);
  73MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
  74
  75static int wdt_start = 0x443;
  76module_param(wdt_start, int, 0);
  77MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
  78
  79/*
  80 * The 60xx board can use watchdog timeout values from one second
  81 * to several minutes.  The default is one second, so if we reset
  82 * the watchdog every ~250ms we should be safe.
  83 */
  84
  85#define WDT_INTERVAL (HZ/4+1)
  86
  87/*
  88 * We must not require too good response from the userspace daemon.
  89 * Here we require the userspace daemon to send us a heartbeat
  90 * char to /dev/watchdog every 30 seconds.
  91 * If the daemon pulses us every 25 seconds, we can still afford
  92 * a 5 second scheduling delay on the (high priority) daemon. That
  93 * should be sufficient for a box under any load.
  94 */
  95
  96#define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
  97static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
  98module_param(timeout, int, 0);
  99MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 100
 101static int nowayout = WATCHDOG_NOWAYOUT;
 102module_param(nowayout, int, 0);
 103MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 104
 105static void wdt_timer_ping(unsigned long);
 106static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
 107static unsigned long next_heartbeat;
 108static unsigned long wdt_is_open;
 109static char wdt_expect_close;
 110
 111/*
 112 *      Whack the dog
 113 */
 114
 115static void wdt_timer_ping(unsigned long data)
 116{
 117        /* If we got a heartbeat pulse within the WDT_US_INTERVAL
 118         * we agree to ping the WDT
 119         */
 120        if(time_before(jiffies, next_heartbeat))
 121        {
 122                /* Ping the WDT by reading from wdt_start */
 123                inb_p(wdt_start);
 124                /* Re-set the timer interval */
 125                mod_timer(&timer, jiffies + WDT_INTERVAL);
 126        } else {
 127                printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
 128        }
 129}
 130
 131/*
 132 * Utility routines
 133 */
 134
 135static void wdt_startup(void)
 136{
 137        next_heartbeat = jiffies + (timeout * HZ);
 138
 139        /* Start the timer */
 140        mod_timer(&timer, jiffies + WDT_INTERVAL);
 141        printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
 142}
 143
 144static void wdt_turnoff(void)
 145{
 146        /* Stop the timer */
 147        del_timer(&timer);
 148        inb_p(wdt_stop);
 149        printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
 150}
 151
 152static void wdt_keepalive(void)
 153{
 154        /* user land ping */
 155        next_heartbeat = jiffies + (timeout * HZ);
 156}
 157
 158/*
 159 * /dev/watchdog handling
 160 */
 161
 162static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
 163{
 164        /* See if we got the magic character 'V' and reload the timer */
 165        if(count)
 166        {
 167                if (!nowayout)
 168                {
 169                        size_t ofs;
 170
 171                        /* note: just in case someone wrote the magic character
 172                         * five months ago... */
 173                        wdt_expect_close = 0;
 174
 175                        /* scan to see whether or not we got the magic character */
 176                        for(ofs = 0; ofs != count; ofs++)
 177                        {
 178                                char c;
 179                                if(get_user(c, buf+ofs))
 180                                        return -EFAULT;
 181                                if(c == 'V')
 182                                        wdt_expect_close = 42;
 183                        }
 184                }
 185
 186                /* Well, anyhow someone wrote to us, we should return that favour */
 187                wdt_keepalive();
 188        }
 189        return count;
 190}
 191
 192static int fop_open(struct inode * inode, struct file * file)
 193{
 194        /* Just in case we're already talking to someone... */
 195        if(test_and_set_bit(0, &wdt_is_open))
 196                return -EBUSY;
 197
 198        if (nowayout)
 199                __module_get(THIS_MODULE);
 200
 201        /* Good, fire up the show */
 202        wdt_startup();
 203        return nonseekable_open(inode, file);
 204}
 205
 206static int fop_close(struct inode * inode, struct file * file)
 207{
 208        if(wdt_expect_close == 42)
 209                wdt_turnoff();
 210        else {
 211                del_timer(&timer);
 212                printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
 213        }
 214        clear_bit(0, &wdt_is_open);
 215        wdt_expect_close = 0;
 216        return 0;
 217}
 218
 219static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 220        unsigned long arg)
 221{
 222        void __user *argp = (void __user *)arg;
 223        int __user *p = argp;
 224        static struct watchdog_info ident=
 225        {
 226                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
 227                .firmware_version = 1,
 228                .identity = "SBC60xx",
 229        };
 230
 231        switch(cmd)
 232        {
 233                default:
 234                        return -ENOTTY;
 235                case WDIOC_GETSUPPORT:
 236                        return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
 237                case WDIOC_GETSTATUS:
 238                case WDIOC_GETBOOTSTATUS:
 239                        return put_user(0, p);
 240                case WDIOC_KEEPALIVE:
 241                        wdt_keepalive();
 242                        return 0;
 243                case WDIOC_SETOPTIONS:
 244                {
 245                        int new_options, retval = -EINVAL;
 246
 247                        if(get_user(new_options, p))
 248                                return -EFAULT;
 249
 250                        if(new_options & WDIOS_DISABLECARD) {
 251                                wdt_turnoff();
 252                                retval = 0;
 253                        }
 254
 255                        if(new_options & WDIOS_ENABLECARD) {
 256                                wdt_startup();
 257                                retval = 0;
 258                        }
 259
 260                        return retval;
 261                }
 262                case WDIOC_SETTIMEOUT:
 263                {
 264                        int new_timeout;
 265
 266                        if(get_user(new_timeout, p))
 267                                return -EFAULT;
 268
 269                        if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
 270                                return -EINVAL;
 271
 272                        timeout = new_timeout;
 273                        wdt_keepalive();
 274                        /* Fall through */
 275                }
 276                case WDIOC_GETTIMEOUT:
 277                        return put_user(timeout, p);
 278        }
 279}
 280
 281static const struct file_operations wdt_fops = {
 282        .owner          = THIS_MODULE,
 283        .llseek         = no_llseek,
 284        .write          = fop_write,
 285        .open           = fop_open,
 286        .release        = fop_close,
 287        .ioctl          = fop_ioctl,
 288};
 289
 290static struct miscdevice wdt_miscdev = {
 291        .minor = WATCHDOG_MINOR,
 292        .name = "watchdog",
 293        .fops = &wdt_fops,
 294};
 295
 296/*
 297 *      Notifier for system down
 298 */
 299
 300static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
 301        void *unused)
 302{
 303        if(code==SYS_DOWN || code==SYS_HALT)
 304                wdt_turnoff();
 305        return NOTIFY_DONE;
 306}
 307
 308/*
 309 *      The WDT needs to learn about soft shutdowns in order to
 310 *      turn the timebomb registers off.
 311 */
 312
 313static struct notifier_block wdt_notifier=
 314{
 315        .notifier_call = wdt_notify_sys,
 316};
 317
 318static void __exit sbc60xxwdt_unload(void)
 319{
 320        wdt_turnoff();
 321
 322        /* Deregister */
 323        misc_deregister(&wdt_miscdev);
 324
 325        unregister_reboot_notifier(&wdt_notifier);
 326        if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 327                release_region(wdt_stop,1);
 328        release_region(wdt_start,1);
 329}
 330
 331static int __init sbc60xxwdt_init(void)
 332{
 333        int rc = -EBUSY;
 334
 335        if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
 336        {
 337                timeout = WATCHDOG_TIMEOUT;
 338                printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
 339                        timeout);
 340        }
 341
 342        if (!request_region(wdt_start, 1, "SBC 60XX WDT"))
 343        {
 344                printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 345                        wdt_start);
 346                rc = -EIO;
 347                goto err_out;
 348        }
 349
 350        /* We cannot reserve 0x45 - the kernel already has! */
 351        if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 352        {
 353                if (!request_region(wdt_stop, 1, "SBC 60XX WDT"))
 354                {
 355                        printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
 356                                wdt_stop);
 357                        rc = -EIO;
 358                        goto err_out_region1;
 359                }
 360        }
 361
 362        rc = misc_register(&wdt_miscdev);
 363        if (rc)
 364        {
 365                printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
 366                        wdt_miscdev.minor, rc);
 367                goto err_out_region2;
 368        }
 369
 370        rc = register_reboot_notifier(&wdt_notifier);
 371        if (rc)
 372        {
 373                printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
 374                        rc);
 375                goto err_out_miscdev;
 376        }
 377
 378        printk(KERN_INFO PFX "WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
 379                timeout, nowayout);
 380
 381        return 0;
 382
 383err_out_miscdev:
 384        misc_deregister(&wdt_miscdev);
 385err_out_region2:
 386        if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
 387                release_region(wdt_stop,1);
 388err_out_region1:
 389        release_region(wdt_start,1);
 390err_out:
 391        return rc;
 392}
 393
 394module_init(sbc60xxwdt_init);
 395module_exit(sbc60xxwdt_unload);
 396
 397MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
 398MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
 399MODULE_LICENSE("GPL");
 400MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 401