linux/drivers/watchdog/sbc_epx_c3.c
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   1/*
   2 *      SBC EPX C3 0.1  A Hardware Watchdog Device for the Winsystems EPX-C3
   3 *      single board computer
   4 *
   5 *      (c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
   6 *      Reserved.
   7 *
   8 *      This program is free software; you can redistribute it and/or
   9 *      modify it under the terms of the GNU General Public License
  10 *      as published by the Free Software Foundation; either version
  11 *      2 of the License, or (at your option) any later version.
  12 *
  13 *      based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
  14 */
  15
  16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18#include <linux/module.h>
  19#include <linux/moduleparam.h>
  20#include <linux/types.h>
  21#include <linux/kernel.h>
  22#include <linux/fs.h>
  23#include <linux/mm.h>
  24#include <linux/miscdevice.h>
  25#include <linux/watchdog.h>
  26#include <linux/notifier.h>
  27#include <linux/reboot.h>
  28#include <linux/init.h>
  29#include <linux/ioport.h>
  30#include <linux/uaccess.h>
  31#include <linux/io.h>
  32
  33static int epx_c3_alive;
  34
  35#define WATCHDOG_TIMEOUT 1              /* 1 sec default timeout */
  36
  37static bool nowayout = WATCHDOG_NOWAYOUT;
  38module_param(nowayout, bool, 0);
  39MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  40                                        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42#define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
  43#define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
  44
  45static void epx_c3_start(void)
  46{
  47        outb(1, EPXC3_WATCHDOG_CTL_REG);
  48}
  49
  50static void epx_c3_stop(void)
  51{
  52
  53        outb(0, EPXC3_WATCHDOG_CTL_REG);
  54
  55        pr_info("Stopped watchdog timer\n");
  56}
  57
  58static void epx_c3_pet(void)
  59{
  60        outb(1, EPXC3_WATCHDOG_PET_REG);
  61}
  62
  63/*
  64 *      Allow only one person to hold it open
  65 */
  66static int epx_c3_open(struct inode *inode, struct file *file)
  67{
  68        if (epx_c3_alive)
  69                return -EBUSY;
  70
  71        if (nowayout)
  72                __module_get(THIS_MODULE);
  73
  74        /* Activate timer */
  75        epx_c3_start();
  76        epx_c3_pet();
  77
  78        epx_c3_alive = 1;
  79        pr_info("Started watchdog timer\n");
  80
  81        return nonseekable_open(inode, file);
  82}
  83
  84static int epx_c3_release(struct inode *inode, struct file *file)
  85{
  86        /* Shut off the timer.
  87         * Lock it in if it's a module and we defined ...NOWAYOUT */
  88        if (!nowayout)
  89                epx_c3_stop();          /* Turn the WDT off */
  90
  91        epx_c3_alive = 0;
  92
  93        return 0;
  94}
  95
  96static ssize_t epx_c3_write(struct file *file, const char __user *data,
  97                        size_t len, loff_t *ppos)
  98{
  99        /* Refresh the timer. */
 100        if (len)
 101                epx_c3_pet();
 102        return len;
 103}
 104
 105static long epx_c3_ioctl(struct file *file, unsigned int cmd,
 106                                                unsigned long arg)
 107{
 108        int options, retval = -EINVAL;
 109        int __user *argp = (void __user *)arg;
 110        static const struct watchdog_info ident = {
 111                .options                = WDIOF_KEEPALIVEPING,
 112                .firmware_version       = 0,
 113                .identity               = "Winsystems EPX-C3 H/W Watchdog",
 114        };
 115
 116        switch (cmd) {
 117        case WDIOC_GETSUPPORT:
 118                if (copy_to_user(argp, &ident, sizeof(ident)))
 119                        return -EFAULT;
 120                return 0;
 121        case WDIOC_GETSTATUS:
 122        case WDIOC_GETBOOTSTATUS:
 123                return put_user(0, argp);
 124        case WDIOC_SETOPTIONS:
 125                if (get_user(options, argp))
 126                        return -EFAULT;
 127
 128                if (options & WDIOS_DISABLECARD) {
 129                        epx_c3_stop();
 130                        retval = 0;
 131                }
 132
 133                if (options & WDIOS_ENABLECARD) {
 134                        epx_c3_start();
 135                        retval = 0;
 136                }
 137
 138                return retval;
 139        case WDIOC_KEEPALIVE:
 140                epx_c3_pet();
 141                return 0;
 142        case WDIOC_GETTIMEOUT:
 143                return put_user(WATCHDOG_TIMEOUT, argp);
 144        default:
 145                return -ENOTTY;
 146        }
 147}
 148
 149static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
 150                                void *unused)
 151{
 152        if (code == SYS_DOWN || code == SYS_HALT)
 153                epx_c3_stop();          /* Turn the WDT off */
 154
 155        return NOTIFY_DONE;
 156}
 157
 158static const struct file_operations epx_c3_fops = {
 159        .owner          = THIS_MODULE,
 160        .llseek         = no_llseek,
 161        .write          = epx_c3_write,
 162        .unlocked_ioctl = epx_c3_ioctl,
 163        .open           = epx_c3_open,
 164        .release        = epx_c3_release,
 165};
 166
 167static struct miscdevice epx_c3_miscdev = {
 168        .minor          = WATCHDOG_MINOR,
 169        .name           = "watchdog",
 170        .fops           = &epx_c3_fops,
 171};
 172
 173static struct notifier_block epx_c3_notifier = {
 174        .notifier_call = epx_c3_notify_sys,
 175};
 176
 177static int __init watchdog_init(void)
 178{
 179        int ret;
 180
 181        if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
 182                return -EBUSY;
 183
 184        ret = register_reboot_notifier(&epx_c3_notifier);
 185        if (ret) {
 186                pr_err("cannot register reboot notifier (err=%d)\n", ret);
 187                goto out;
 188        }
 189
 190        ret = misc_register(&epx_c3_miscdev);
 191        if (ret) {
 192                pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 193                       WATCHDOG_MINOR, ret);
 194                unregister_reboot_notifier(&epx_c3_notifier);
 195                goto out;
 196        }
 197
 198        pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
 199
 200        return 0;
 201
 202out:
 203        release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 204        return ret;
 205}
 206
 207static void __exit watchdog_exit(void)
 208{
 209        misc_deregister(&epx_c3_miscdev);
 210        unregister_reboot_notifier(&epx_c3_notifier);
 211        release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 212}
 213
 214module_init(watchdog_init);
 215module_exit(watchdog_exit);
 216
 217MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
 218MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
 219        "Note that there is no way to probe for this device -- "
 220        "so only use it if you are *sure* you are running on this specific "
 221        "SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
 222MODULE_LICENSE("GPL");
 223MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 224
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