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 #include <linux/smp_lock.h>
  42
  43 static int acq_is_open;
  44 static spinlock_t acq_lock;
  45
  46 /*
  47  *      You must set these - there is no sane way to probe for this board.
  48  */
  49
  50 #define WDT_STOP 0x43
  51 #define WDT_START 0x443
  52
  53 #define WD_TIMO (100*60)                /* 1 minute */
  54
  55
  56 /*
  57  *      Kernel methods.
  58  */
  59
  60
  61 static void acq_ping(void)
  62 {
  63         /* Write a watchdog value */
  64         inb_p(WDT_START);
  65 }
  66
  67 static ssize_t acq_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
  68 {
  69         /*  Can't seek (pwrite) on this device  */
  70         if (ppos != &file->f_pos)
  71                 return -ESPIPE;
  72
  73         if(count)
  74         {
  75                 acq_ping();
  76                 return 1;
  77         }
  78         return 0;
  79 }
  80
  81 static ssize_t acq_read(struct file *file, char *buf, size_t count, loff_t *ppos)
  82 {
  83         return -EINVAL;
  84 }
  85
  86
  87
  88 static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
  89         unsigned long arg)
  90 {
  91         static struct watchdog_info ident=
  92         {
  93                 WDIOF_KEEPALIVEPING, 1, "Acquire WDT"
  94         };
  95
  96         switch(cmd)
  97         {
  98         case WDIOC_GETSUPPORT:
  99           if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
 100             return -EFAULT;
 101           break;
 102
 103         case WDIOC_GETSTATUS:
 104           if (copy_to_user((int *)arg, &acq_is_open,  sizeof(int)))
 105             return -EFAULT;
 106           break;
 107
 108         case WDIOC_KEEPALIVE:
 109           acq_ping();
 110           break;
 111
 112         default:
 113           return -ENOIOCTLCMD;
 114         }
 115         return 0;
 116 }
 117
 118 static int acq_open(struct inode *inode, struct file *file)
 119 {
 120         switch(MINOR(inode->i_rdev))
 121         {
 122                 case WATCHDOG_MINOR:
 123                         spin_lock(&acq_lock);
 124                         if(acq_is_open)
 125                         {
 126                                 spin_unlock(&acq_lock);
 127                                 return -EBUSY;
 128                         }
 129                         /*
 130                          *      Activate
 131                          */
 132
 133                         acq_is_open=1;
 134                         inb_p(WDT_START);
 135                         spin_unlock(&acq_lock);
 136                         return 0;
 137                 default:
 138                         return -ENODEV;
 139         }
 140 }
 141
 142 static int acq_close(struct inode *inode, struct file *file)
 143 {
 144         lock_kernel();
 145         if(MINOR(inode->i_rdev)==WATCHDOG_MINOR)
 146         {
 147                 spin_lock(&acq_lock);
 148 #ifndef CONFIG_WATCHDOG_NOWAYOUT
 149                 inb_p(WDT_STOP);
 150 #endif
 151                 acq_is_open=0;
 152                 spin_unlock(&acq_lock);
 153         }
 154         unlock_kernel();
 155         return 0;
 156 }
 157
 158 /*
 159  *      Notifier for system down
 160  */
 161
 162 static int acq_notify_sys(struct notifier_block *this, unsigned long code,
 163         void *unused)
 164 {
 165         if(code==SYS_DOWN || code==SYS_HALT)
 166         {
 167                 /* Turn the card off */
 168                 inb_p(WDT_STOP);
 169         }
 170         return NOTIFY_DONE;
 171 }
 172
 173 /*
 174  *      Kernel Interfaces
 175  */
 176
 177
 178 static struct file_operations acq_fops = {
 179         owner:          THIS_MODULE,
 180         read:           acq_read,
 181         write:          acq_write,
 182         ioctl:          acq_ioctl,
 183         open:           acq_open,
 184         release:        acq_close,
 185 };
 186
 187 static struct miscdevice acq_miscdev=
 188 {
 189         WATCHDOG_MINOR,
 190         "watchdog",
 191         &acq_fops
 192 };
 193
 194
 195 /*
 196  *      The WDT card needs to learn about soft shutdowns in order to
 197  *      turn the timebomb registers off.
 198  */
 199
 200 static struct notifier_block acq_notifier=
 201 {
 202         acq_notify_sys,
 203         NULL,
 204         0
 205 };
 206
 207 static int __init acq_init(void)
 208 {
 209         printk("WDT driver for Acquire single board computer initialising.\n");
 210
 211         spin_lock_init(&acq_lock);
 212         misc_register(&acq_miscdev);
 213         request_region(WDT_STOP, 1, "Acquire WDT");
 214         request_region(WDT_START, 1, "Acquire WDT");
 215         register_reboot_notifier(&acq_notifier);
 216         return 0;
 217 }
 218
 219 static void __exit acq_exit(void)
 220 {
 221         misc_deregister(&acq_miscdev);
 222         unregister_reboot_notifier(&acq_notifier);
 223         release_region(WDT_STOP,1);
 224         release_region(WDT_START,1);
 225 }
 226
 227 module_init(acq_init);
 228 module_exit(acq_exit);