drivers/char/acquirewdt.c

   1 /*
   2  *      Acquire Single Board Computer Watchdog Timer driver for Linux 2.1.x
   3  *
   4  *      Based on wdt.c. Original copyright messages:
   5  *
   6  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
   7  *                              http://www.redhat.com
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  15  *      warranty for any of this software. This material is provided
  16  *      "AS-IS" and at no charge.
  17  *
  18  *      (c) Copyright 1995    Alan Cox <alan@redhat.com>
  19  *
  20  */
  21
  22 #include <linux/config.h>
  23 #include <linux/module.h>
  24 #include <linux/version.h>
  25 #include <linux/types.h>
  26 #include <linux/errno.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/miscdevice.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/malloc.h>
  32 #include <linux/ioport.h>
  33 #include <linux/fcntl.h>
  34 #include <asm/io.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/system.h>
  37 #include <linux/notifier.h>
  38 #include <linux/reboot.h>
  39 #include <linux/init.h>
  40 #include <linux/spinlock.h>
  41
  42 static int acq_is_open=0;
  43 static spinlock_t acq_lock;
  44
  45 /*
  46  *      You must set these - there is no sane way to probe for this board.
  47  */
  48
  49 #define WDT_STOP 0x43
  50 #define WDT_START 0x443
  51
  52 #define WD_TIMO (100*60)                /* 1 minute */
  53
  54
  55 /*
  56  *      Kernel methods.
  57  */
  58
  59
  60 static void acq_ping(void)
  61 {
  62         /* Write a watchdog value */
  63         inb_p(WDT_START);
  64 }
  65
  66 static ssize_t acq_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
  67 {
  68         /*  Can't seek (pwrite) on this device  */
  69         if (ppos != &file->f_pos)
  70                 return -ESPIPE;
  71
  72         if(count)
  73         {
  74                 acq_ping();
  75                 return 1;
  76         }
  77         return 0;
  78 }
  79
  80 static ssize_t acq_read(struct file *file, char *buf, size_t count, loff_t *ppos)
  81 {
  82         return -EINVAL;
  83 }
  84
  85
  86
  87 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
  88         unsigned long arg)
  89 {
  90         static struct watchdog_info ident=
  91         {
  92                 WDIOF_KEEPALIVEPING, 1, "Acquire WDT"
  93         };
  94
  95         switch(cmd)
  96         {
  97         case WDIOC_GETSUPPORT:
  98           if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
  99             return -EFAULT;
 100           break;
 101
 102         case WDIOC_GETSTATUS:
 103           if (copy_to_user((int *)arg, &acq_is_open,  sizeof(int)))
 104             return -EFAULT;
 105           break;
 106
 107         case WDIOC_KEEPALIVE:
 108           acq_ping();
 109           break;
 110
 111         default:
 112           return -ENOIOCTLCMD;
 113         }
 114         return 0;
 115 }
 116
 117 static int acq_open(struct inode *inode, struct file *file)
 118 {
 119         switch(MINOR(inode->i_rdev))
 120         {
 121                 case WATCHDOG_MINOR:
 122                         spin_lock(&acq_lock);
 123                         if(acq_is_open)
 124                         {
 125                                 spin_unlock(&acq_lock);
 126                                 return -EBUSY;
 127                         }
 128                         /*
 129                          *      Activate
 130                          */
 131
 132                         acq_is_open=1;
 133                         inb_p(WDT_START);
 134                         spin_unlock(&acq_lock);
 135                         return 0;
 136                 default:
 137                         return -ENODEV;
 138         }
 139 }
 140
 141 static int acq_close(struct inode *inode, struct file *file)
 142 {
 143         if(MINOR(inode->i_rdev)==WATCHDOG_MINOR)
 144         {
 145                 spin_lock(&acq_lock);
 146 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 147                 inb_p(WDT_STOP);
 148 #endif
 149                 acq_is_open=0;
 150                 spin_unlock(&acq_lock);
 151         }
 152         return 0;
 153 }
 154
 155 /*
 156  *      Notifier for system down
 157  */
 158
 159 static int acq_notify_sys(struct notifier_block *this, unsigned long code,
 160         void *unused)
 161 {
 162         if(code==SYS_DOWN || code==SYS_HALT)
 163         {
 164                 /* Turn the card off */
 165                 inb_p(WDT_STOP);
 166         }
 167         return NOTIFY_DONE;
 168 }
 169
 170 /*
 171  *      Kernel Interfaces
 172  */
 173
 174
 175 static struct file_operations acq_fops = {
 176         owner:          THIS_MODULE,
 177         read:           acq_read,
 178         write:          acq_write,
 179         ioctl:          acq_ioctl,
 180         open:           acq_open,
 181         release:        acq_close,
 182 };
 183
 184 static struct miscdevice acq_miscdev=
 185 {
 186         WATCHDOG_MINOR,
 187         "watchdog",
 188         &acq_fops
 189 };
 190
 191
 192 /*
 193  *      The WDT card needs to learn about soft shutdowns in order to
 194  *      turn the timebomb registers off.
 195  */
 196
 197 static struct notifier_block acq_notifier=
 198 {
 199         acq_notify_sys,
 200         NULL,
 201         0
 202 };
 203
 204 #ifdef MODULE
 205
 206 #define acq_init init_module
 207
 208 void cleanup_module(void)
 209 {
 210         misc_deregister(&acq_miscdev);
 211         unregister_reboot_notifier(&acq_notifier);
 212         release_region(WDT_STOP,1);
 213         release_region(WDT_START,1);
 214 }
 215
 216 #endif
 217
 218 int __init acq_init(void)
 219 {
 220         printk("WDT driver for Acquire single board computer initialising.\n");
 221
 222         spin_lock_init(&acq_lock);
 223         misc_register(&acq_miscdev);
 224         request_region(WDT_STOP, 1, "Acquire WDT");
 225         request_region(WDT_START, 1, "Acquire WDT");
 226         register_reboot_notifier(&acq_notifier);
 227         return 0;
 228 }
 229