/*
* Acquire Single Board Computer Watchdog Timer driver
*
* Based on wdt.c. Original copyright messages:
*
* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
* http://www.redhat.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
* warranty for any of this software. This material is provided
* "AS-IS" and at no charge.
*
* (c) Copyright 1995 Alan Cox <alan@redhat.com>
*
* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
* Can't add timeout - driver doesn't allow changing value
*/
/*
* Theory of Operation:
* The Watch-Dog Timer is provided to ensure that standalone
* Systems can always recover from catastrophic conditions that
* caused the CPU to crash. This condition may have occured by
* external EMI or a software bug. When the CPU stops working
* correctly, hardware on the board will either perform a hardware
* reset (cold boot) or a non-maskable interrupt (NMI) to bring the
* system back to a known state.
*
* The Watch-Dog Timer is controlled by two I/O Ports.
* 443 hex - Read - Enable or refresh the Watch-Dog Timer
* 043 hex - Read - Disable the Watch-Dog Timer
*
* To enable the Watch-Dog Timer, a read from I/O port 443h must
* be performed. This will enable and activate the countdown timer
* which will eventually time out and either reset the CPU or cause
* an NMI depending on the setting of a jumper. To ensure that this
* reset condition does not occur, the Watch-Dog Timer must be
* periodically refreshed by reading the same I/O port 443h.
* The Watch-Dog Timer is disabled by reading I/O port 043h.
*
* The Watch-Dog Timer Time-Out Period is set via jumpers.
* It can be 1, 2, 10, 20, 110 or 220 seconds.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#define WATCHDOG_NAME "Acquire WDT"
#define PFX WATCHDOG_NAME ": "
#define WATCHDOG_HEARTBEAT 0 /* There is no way to see what the correct time-out period is */
static unsigned long acq_is_open;
static char expect_close;
/*
* You must set these - there is no sane way to probe for this board.
*/
static int wdt_stop = 0x43;
module_param(wdt_stop, int, 0);
MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
static int wdt_start = 0x443;
module_param(wdt_start, int, 0);
MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
/*
* Kernel methods.
*/
static void acq_keepalive(void)
{
/* Write a watchdog value */
inb_p(wdt_start);
}
static void acq_stop(void)
{
/* Turn the card off */
inb_p(wdt_stop);
}
/*
* /dev/watchdog handling.
*/
static ssize_t acq_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if(count) {
if (!nowayout) {
size_t i;
/* note: just in case someone wrote the magic character
* five months ago... */
expect_close = 0;
/* scan to see whether or not we got the magic character */
for (i = 0; i != count; i++) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
/* Well, anyhow someone wrote to us, we should return that favour */
acq_keepalive();
}
return count;
}
static int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int options, retval = -EINVAL;
void __user *argp = (void __user *)arg;
int __user *p = argp;
static struct watchdog_info ident =
{
.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = "Acquire WDT",
};
switch(cmd)
{
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
acq_keepalive();
return 0;
case WDIOC_GETTIMEOUT:
return put_user(WATCHDOG_HEARTBEAT, p);
case WDIOC_SETOPTIONS:
{
if (get_user(options, p))
return -EFAULT;
if (options & WDIOS_DISABLECARD)
{
acq_stop();
retval = 0;
}
if (options & WDIOS_ENABLECARD)
{
acq_keepalive();
retval = 0;
}
return retval;
}
default:
return -ENOTTY;
}
}
static int acq_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &acq_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Activate */
acq_keepalive();
return nonseekable_open(inode, file);
}
static int acq_close(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
acq_stop();
} else {
printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
acq_keepalive();
}
clear_bit(0, &acq_is_open);
expect_close = 0;
return 0;
}
/*
* Notifier for system down
*/
static int acq_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if(code==SYS_DOWN || code==SYS_HALT) {
/* Turn the WDT off */
acq_stop();
}
return NOTIFY_DONE;
}
/*
* Kernel Interfaces
*/
static const struct file_operations acq_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = acq_write,
.ioctl = acq_ioctl,
.open = acq_open,
.release = acq_close,
};
static struct miscdevice acq_miscdev=
{
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &acq_fops,
};
/*
* The WDT card needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block acq_notifier =
{
.notifier_call = acq_notify_sys,
};
static int __init acq_init(void)
{
int ret;
printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n");
if (wdt_stop != wdt_start) {
if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
wdt_stop);
ret = -EIO;
goto out;
}
}
if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
wdt_start);
ret = -EIO;
goto unreg_stop;
}
ret = register_reboot_notifier(&acq_notifier);
if (ret != 0) {
printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
ret);
goto unreg_regions;
}
ret = misc_register(&acq_miscdev);
if (ret != 0) {
printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
goto unreg_reboot;
}
printk (KERN_INFO PFX "initialized. (nowayout=%d)\n",
nowayout);
return 0;
unreg_reboot:
unregister_reboot_notifier(&acq_notifier);
unreg_regions:
release_region(wdt_start, 1);
unreg_stop:
if (wdt_stop != wdt_start)
release_region(wdt_stop, 1);
out:
return ret;
}
static void __exit acq_exit(void)
{
misc_deregister(&acq_miscdev);
unregister_reboot_notifier(&acq_notifier);
if(wdt_stop != wdt_start)
release_region(wdt_stop,1);
release_region(wdt_start,1);
}
module_init(acq_init);
module_exit(acq_exit);
MODULE_AUTHOR("David Woodhouse");
MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
