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linux-stable-rt/drivers/char/watchdog/ib700wdt.c

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/*
* IB700 Single Board Computer WDT driver
*
* (c) Copyright 2001 Charles Howes <chowes@vsol.net>
*
* Based on advantechwdt.c which is based on acquirewdt.c which
* is based on wdt.c.
*
* (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
*
* Based on acquirewdt.c which is 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
* Added timeout module option to override default
*
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/moduleparam.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>
static unsigned long ibwdt_is_open;
static spinlock_t ibwdt_lock;
static char expect_close;
#define PFX "ib700wdt: "
/*
*
* Watchdog Timer Configuration
*
* The function of the watchdog timer is to reset the system
* automatically and is defined at I/O port 0443H. To enable the
* watchdog timer and allow the system to reset, write I/O port 0443H.
* To disable the timer, write I/O port 0441H for the system to stop the
* watchdog function. The timer has a tolerance of 20% for its
* intervals.
*
* The following describes how the timer should be programmed.
*
* Enabling Watchdog:
* MOV AX,000FH (Choose the values from 0 to F)
* MOV DX,0443H
* OUT DX,AX
*
* Disabling Watchdog:
* MOV AX,000FH (Any value is fine.)
* MOV DX,0441H
* OUT DX,AX
*
* Watchdog timer control table:
* Level Value Time/sec | Level Value Time/sec
* 1 F 0 | 9 7 16
* 2 E 2 | 10 6 18
* 3 D 4 | 11 5 20
* 4 C 6 | 12 4 22
* 5 B 8 | 13 3 24
* 6 A 10 | 14 2 26
* 7 9 12 | 15 1 28
* 8 8 14 | 16 0 30
*
*/
static int wd_times[] = {
30, /* 0x0 */
28, /* 0x1 */
26, /* 0x2 */
24, /* 0x3 */
22, /* 0x4 */
20, /* 0x5 */
18, /* 0x6 */
16, /* 0x7 */
14, /* 0x8 */
12, /* 0x9 */
10, /* 0xA */
8, /* 0xB */
6, /* 0xC */
4, /* 0xD */
2, /* 0xE */
0, /* 0xF */
};
#define WDT_STOP 0x441
#define WDT_START 0x443
/* Default timeout */
#define WD_TIMO 0 /* 30 seconds +/- 20%, from table */
static int wd_margin = WD_TIMO;
#ifdef CONFIG_WATCHDOG_NOWAYOUT
static int nowayout = 1;
#else
static int nowayout = 0;
#endif
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
/*
* Kernel methods.
*/
static void
ibwdt_ping(void)
{
/* Write a watchdog value */
outb_p(wd_margin, WDT_START);
}
static ssize_t
ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
if (count) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
expect_close = 0;
for (i = 0; i != count; i++) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
ibwdt_ping();
}
return count;
}
static int
ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int i, new_margin;
void __user *argp = (void __user *)arg;
int __user *p = argp;
static struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = "IB700 WDT",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &ident, sizeof(ident)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
ibwdt_ping();
break;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, p))
return -EFAULT;
if ((new_margin < 0) || (new_margin > 30))
return -EINVAL;
for (i = 0x0F; i > -1; i--)
if (wd_times[i] > new_margin)
break;
wd_margin = i;
ibwdt_ping();
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(wd_times[wd_margin], p);
break;
default:
return -ENOIOCTLCMD;
}
return 0;
}
static int
ibwdt_open(struct inode *inode, struct file *file)
{
spin_lock(&ibwdt_lock);
if (test_and_set_bit(0, &ibwdt_is_open)) {
spin_unlock(&ibwdt_lock);
return -EBUSY;
}
if (nowayout)
__module_get(THIS_MODULE);
/* Activate */
ibwdt_ping();
spin_unlock(&ibwdt_lock);
return nonseekable_open(inode, file);
}
static int
ibwdt_close(struct inode *inode, struct file *file)
{
spin_lock(&ibwdt_lock);
if (expect_close == 42)
outb_p(0, WDT_STOP);
else
printk(KERN_CRIT PFX "WDT device closed unexpectedly. WDT will not stop!\n");
clear_bit(0, &ibwdt_is_open);
expect_close = 0;
spin_unlock(&ibwdt_lock);
return 0;
}
/*
* Notifier for system down
*/
static int
ibwdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT) {
/* Turn the WDT off */
outb_p(0, WDT_STOP);
}
return NOTIFY_DONE;
}
/*
* Kernel Interfaces
*/
static struct file_operations ibwdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = ibwdt_write,
.ioctl = ibwdt_ioctl,
.open = ibwdt_open,
.release = ibwdt_close,
};
static struct miscdevice ibwdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ibwdt_fops,
};
/*
* The WDT needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block ibwdt_notifier = {
.notifier_call = ibwdt_notify_sys,
};
static int __init ibwdt_init(void)
{
int res;
printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
spin_lock_init(&ibwdt_lock);
res = misc_register(&ibwdt_miscdev);
if (res) {
printk (KERN_ERR PFX "failed to register misc device\n");
goto out_nomisc;
}
#if WDT_START != WDT_STOP
if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
res = -EIO;
goto out_nostopreg;
}
#endif
if (!request_region(WDT_START, 1, "IB700 WDT")) {
printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
res = -EIO;
goto out_nostartreg;
}
res = register_reboot_notifier(&ibwdt_notifier);
if (res) {
printk (KERN_ERR PFX "Failed to register reboot notifier.\n");
goto out_noreboot;
}
return 0;
out_noreboot:
release_region(WDT_START, 1);
out_nostartreg:
#if WDT_START != WDT_STOP
release_region(WDT_STOP, 1);
#endif
out_nostopreg:
misc_deregister(&ibwdt_miscdev);
out_nomisc:
return res;
}
static void __exit
ibwdt_exit(void)
{
misc_deregister(&ibwdt_miscdev);
unregister_reboot_notifier(&ibwdt_notifier);
#if WDT_START != WDT_STOP
release_region(WDT_STOP,1);
#endif
release_region(WDT_START,1);
}
module_init(ibwdt_init);
module_exit(ibwdt_exit);
MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
MODULE_DESCRIPTION("IB700 SBC watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
/* end of ib700wdt.c */
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