linux/drivers/watchdog/wafer5823wdt.c
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   1/*
   2 *      ICP Wafer 5823 Single Board Computer WDT driver
   3 *      http://www.icpamerica.com/wafer_5823.php
   4 *      May also work on other similar models
   5 *
   6 *      (c) Copyright 2002 Justin Cormack <justin@street-vision.com>
   7 *
   8 *      Release 0.02
   9 *
  10 *      Based on advantechwdt.c which is based on wdt.c.
  11 *      Original copyright messages:
  12 *
  13 *      (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  14 *                                              All Rights Reserved.
  15 *
  16 *      This program is free software; you can redistribute it and/or
  17 *      modify it under the terms of the GNU General Public License
  18 *      as published by the Free Software Foundation; either version
  19 *      2 of the License, or (at your option) any later version.
  20 *
  21 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  22 *      warranty for any of this software. This material is provided
  23 *      "AS-IS" and at no charge.
  24 *
  25 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  26 *
  27 */
  28
  29#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  30
  31#include <linux/module.h>
  32#include <linux/moduleparam.h>
  33#include <linux/miscdevice.h>
  34#include <linux/watchdog.h>
  35#include <linux/fs.h>
  36#include <linux/ioport.h>
  37#include <linux/notifier.h>
  38#include <linux/reboot.h>
  39#include <linux/init.h>
  40#include <linux/spinlock.h>
  41#include <linux/io.h>
  42#include <linux/uaccess.h>
  43
  44#define WATCHDOG_NAME "Wafer 5823 WDT"
  45#define PFX WATCHDOG_NAME ": "
  46#define WD_TIMO 60                      /* 60 sec default timeout */
  47
  48static unsigned long wafwdt_is_open;
  49static char expect_close;
  50static DEFINE_SPINLOCK(wafwdt_lock);
  51
  52/*
  53 *      You must set these - there is no sane way to probe for this board.
  54 *
  55 *      To enable, write the timeout value in seconds (1 to 255) to I/O
  56 *      port WDT_START, then read the port to start the watchdog. To pat
  57 *      the dog, read port WDT_STOP to stop the timer, then read WDT_START
  58 *      to restart it again.
  59 */
  60
  61static int wdt_stop = 0x843;
  62static int wdt_start = 0x443;
  63
  64static int timeout = WD_TIMO;  /* in seconds */
  65module_param(timeout, int, 0);
  66MODULE_PARM_DESC(timeout,
  67                "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
  68                                __MODULE_STRING(WD_TIMO) ".");
  69
  70static bool nowayout = WATCHDOG_NOWAYOUT;
  71module_param(nowayout, bool, 0);
  72MODULE_PARM_DESC(nowayout,
  73                "Watchdog cannot be stopped once started (default="
  74                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  75
  76static void wafwdt_ping(void)
  77{
  78        /* pat watchdog */
  79        spin_lock(&wafwdt_lock);
  80        inb_p(wdt_stop);
  81        inb_p(wdt_start);
  82        spin_unlock(&wafwdt_lock);
  83}
  84
  85static void wafwdt_start(void)
  86{
  87        /* start up watchdog */
  88        outb_p(timeout, wdt_start);
  89        inb_p(wdt_start);
  90}
  91
  92static void wafwdt_stop(void)
  93{
  94        /* stop watchdog */
  95        inb_p(wdt_stop);
  96}
  97
  98static ssize_t wafwdt_write(struct file *file, const char __user *buf,
  99                                                size_t count, loff_t *ppos)
 100{
 101        /* See if we got the magic character 'V' and reload the timer */
 102        if (count) {
 103                if (!nowayout) {
 104                        size_t i;
 105
 106                        /* In case it was set long ago */
 107                        expect_close = 0;
 108
 109                        /* scan to see whether or not we got the magic
 110                           character */
 111                        for (i = 0; i != count; i++) {
 112                                char c;
 113                                if (get_user(c, buf + i))
 114                                        return -EFAULT;
 115                                if (c == 'V')
 116                                        expect_close = 42;
 117                        }
 118                }
 119                /* Well, anyhow someone wrote to us, we should
 120                   return that favour */
 121                wafwdt_ping();
 122        }
 123        return count;
 124}
 125
 126static long wafwdt_ioctl(struct file *file, unsigned int cmd,
 127                                                        unsigned long arg)
 128{
 129        int new_timeout;
 130        void __user *argp = (void __user *)arg;
 131        int __user *p = argp;
 132        static const struct watchdog_info ident = {
 133                .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
 134                                                        WDIOF_MAGICCLOSE,
 135                .firmware_version = 1,
 136                .identity = "Wafer 5823 WDT",
 137        };
 138
 139        switch (cmd) {
 140        case WDIOC_GETSUPPORT:
 141                if (copy_to_user(argp, &ident, sizeof(ident)))
 142                        return -EFAULT;
 143                break;
 144
 145        case WDIOC_GETSTATUS:
 146        case WDIOC_GETBOOTSTATUS:
 147                return put_user(0, p);
 148
 149        case WDIOC_SETOPTIONS:
 150        {
 151                int options, retval = -EINVAL;
 152
 153                if (get_user(options, p))
 154                        return -EFAULT;
 155
 156                if (options & WDIOS_DISABLECARD) {
 157                        wafwdt_stop();
 158                        retval = 0;
 159                }
 160
 161                if (options & WDIOS_ENABLECARD) {
 162                        wafwdt_start();
 163                        retval = 0;
 164                }
 165
 166                return retval;
 167        }
 168
 169        case WDIOC_KEEPALIVE:
 170                wafwdt_ping();
 171                break;
 172
 173        case WDIOC_SETTIMEOUT:
 174                if (get_user(new_timeout, p))
 175                        return -EFAULT;
 176                if ((new_timeout < 1) || (new_timeout > 255))
 177                        return -EINVAL;
 178                timeout = new_timeout;
 179                wafwdt_stop();
 180                wafwdt_start();
 181                /* Fall */
 182        case WDIOC_GETTIMEOUT:
 183                return put_user(timeout, p);
 184
 185        default:
 186                return -ENOTTY;
 187        }
 188        return 0;
 189}
 190
 191static int wafwdt_open(struct inode *inode, struct file *file)
 192{
 193        if (test_and_set_bit(0, &wafwdt_is_open))
 194                return -EBUSY;
 195
 196        /*
 197         *      Activate
 198         */
 199        wafwdt_start();
 200        return nonseekable_open(inode, file);
 201}
 202
 203static int wafwdt_close(struct inode *inode, struct file *file)
 204{
 205        if (expect_close == 42)
 206                wafwdt_stop();
 207        else {
 208                pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
 209                wafwdt_ping();
 210        }
 211        clear_bit(0, &wafwdt_is_open);
 212        expect_close = 0;
 213        return 0;
 214}
 215
 216/*
 217 *      Notifier for system down
 218 */
 219
 220static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code,
 221                                                                void *unused)
 222{
 223        if (code == SYS_DOWN || code == SYS_HALT)
 224                wafwdt_stop();
 225        return NOTIFY_DONE;
 226}
 227
 228/*
 229 *      Kernel Interfaces
 230 */
 231
 232static const struct file_operations wafwdt_fops = {
 233        .owner          = THIS_MODULE,
 234        .llseek         = no_llseek,
 235        .write          = wafwdt_write,
 236        .unlocked_ioctl = wafwdt_ioctl,
 237        .open           = wafwdt_open,
 238        .release        = wafwdt_close,
 239};
 240
 241static struct miscdevice wafwdt_miscdev = {
 242        .minor  = WATCHDOG_MINOR,
 243        .name   = "watchdog",
 244        .fops   = &wafwdt_fops,
 245};
 246
 247/*
 248 *      The WDT needs to learn about soft shutdowns in order to
 249 *      turn the timebomb registers off.
 250 */
 251
 252static struct notifier_block wafwdt_notifier = {
 253        .notifier_call = wafwdt_notify_sys,
 254};
 255
 256static int __init wafwdt_init(void)
 257{
 258        int ret;
 259
 260        pr_info("WDT driver for Wafer 5823 single board computer initialising\n");
 261
 262        if (timeout < 1 || timeout > 255) {
 263                timeout = WD_TIMO;
 264                pr_info("timeout value must be 1 <= x <= 255, using %d\n",
 265                        timeout);
 266        }
 267
 268        if (wdt_stop != wdt_start) {
 269                if (!request_region(wdt_stop, 1, "Wafer 5823 WDT")) {
 270                        pr_err("I/O address 0x%04x already in use\n", wdt_stop);
 271                        ret = -EIO;
 272                        goto error;
 273                }
 274        }
 275
 276        if (!request_region(wdt_start, 1, "Wafer 5823 WDT")) {
 277                pr_err("I/O address 0x%04x already in use\n", wdt_start);
 278                ret = -EIO;
 279                goto error2;
 280        }
 281
 282        ret = register_reboot_notifier(&wafwdt_notifier);
 283        if (ret != 0) {
 284                pr_err("cannot register reboot notifier (err=%d)\n", ret);
 285                goto error3;
 286        }
 287
 288        ret = misc_register(&wafwdt_miscdev);
 289        if (ret != 0) {
 290                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 291                       WATCHDOG_MINOR, ret);
 292                goto error4;
 293        }
 294
 295        pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
 296                timeout, nowayout);
 297
 298        return ret;
 299error4:
 300        unregister_reboot_notifier(&wafwdt_notifier);
 301error3:
 302        release_region(wdt_start, 1);
 303error2:
 304        if (wdt_stop != wdt_start)
 305                release_region(wdt_stop, 1);
 306error:
 307        return ret;
 308}
 309
 310static void __exit wafwdt_exit(void)
 311{
 312        misc_deregister(&wafwdt_miscdev);
 313        unregister_reboot_notifier(&wafwdt_notifier);
 314        if (wdt_stop != wdt_start)
 315                release_region(wdt_stop, 1);
 316        release_region(wdt_start, 1);
 317}
 318
 319module_init(wafwdt_init);
 320module_exit(wafwdt_exit);
 321
 322MODULE_AUTHOR("Justin Cormack");
 323MODULE_DESCRIPTION("ICP Wafer 5823 Single Board Computer WDT driver");
 324MODULE_LICENSE("GPL");
 325MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 326
 327/* end of wafer5823wdt.c */
 328
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