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kernel/drivers/watchdog/ib700wdt.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* 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@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* 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@lxorguk.ukuu.org.uk>
*
* 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
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/moduleparam.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/uaccess.h>
static struct platform_device *ibwdt_platform_device;
static unsigned long ibwdt_is_open;
static DEFINE_SPINLOCK(ibwdt_lock);
static char expect_close;
/* Module information */
#define DRV_NAME "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
*
*/
#define WDT_STOP 0x441
#define WDT_START 0x443
/* Default timeout */
#define WATCHDOG_TIMEOUT 30 /* 30 seconds +/- 20% */
static int timeout = WATCHDOG_TIMEOUT; /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. 0<= timeout <=30, default="
__MODULE_STRING(WATCHDOG_TIMEOUT) ".");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
/*
* Watchdog Operations
*/
static void ibwdt_ping(void)
{
int wd_margin = 15 - ((timeout + 1) / 2);
spin_lock(&ibwdt_lock);
/* Write a watchdog value */
outb_p(wd_margin, WDT_START);
spin_unlock(&ibwdt_lock);
}
static void ibwdt_disable(void)
{
spin_lock(&ibwdt_lock);
outb_p(0, WDT_STOP);
spin_unlock(&ibwdt_lock);
}
static int ibwdt_set_heartbeat(int t)
{
if (t < 0 || t > 30)
return -EINVAL;
timeout = t;
return 0;
}
/*
* /dev/watchdog handling
*/
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 long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int new_margin;
void __user *argp = (void __user *)arg;
int __user *p = argp;
static const 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:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_SETOPTIONS:
{
int options, retval = -EINVAL;
if (get_user(options, p))
return -EFAULT;
if (options & WDIOS_DISABLECARD) {
ibwdt_disable();
retval = 0;
}
if (options & WDIOS_ENABLECARD) {
ibwdt_ping();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
ibwdt_ping();
break;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, p))
return -EFAULT;
if (ibwdt_set_heartbeat(new_margin))
return -EINVAL;
ibwdt_ping();
fallthrough;
case WDIOC_GETTIMEOUT:
return put_user(timeout, p);
default:
return -ENOTTY;
}
return 0;
}
static int ibwdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &ibwdt_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Activate */
ibwdt_ping();
return stream_open(inode, file);
}
static int ibwdt_close(struct inode *inode, struct file *file)
{
if (expect_close == 42) {
ibwdt_disable();
} else {
pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");
ibwdt_ping();
}
clear_bit(0, &ibwdt_is_open);
expect_close = 0;
return 0;
}
/*
* Kernel Interfaces
*/
static const struct file_operations ibwdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = ibwdt_write,
.unlocked_ioctl = ibwdt_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = ibwdt_open,
.release = ibwdt_close,
};
static struct miscdevice ibwdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ibwdt_fops,
};
/*
* Init & exit routines
*/
static int __init ibwdt_probe(struct platform_device *dev)
{
int res;
#if WDT_START != WDT_STOP
if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
pr_err("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")) {
pr_err("START method I/O %X is not available\n", WDT_START);
res = -EIO;
goto out_nostartreg;
}
/* Check that the heartbeat value is within it's range ;
* if not reset to the default */
if (ibwdt_set_heartbeat(timeout)) {
ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
}
res = misc_register(&ibwdt_miscdev);
if (res) {
pr_err("failed to register misc device\n");
goto out_nomisc;
}
return 0;
out_nomisc:
release_region(WDT_START, 1);
out_nostartreg:
#if WDT_START != WDT_STOP
release_region(WDT_STOP, 1);
#endif
out_nostopreg:
return res;
}
static int ibwdt_remove(struct platform_device *dev)
{
misc_deregister(&ibwdt_miscdev);
release_region(WDT_START, 1);
#if WDT_START != WDT_STOP
release_region(WDT_STOP, 1);
#endif
return 0;
}
static void ibwdt_shutdown(struct platform_device *dev)
{
/* Turn the WDT off if we have a soft shutdown */
ibwdt_disable();
}
static struct platform_driver ibwdt_driver = {
.remove = ibwdt_remove,
.shutdown = ibwdt_shutdown,
.driver = {
.name = DRV_NAME,
},
};
static int __init ibwdt_init(void)
{
int err;
pr_info("WDT driver for IB700 single board computer initialising\n");
ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
-1, NULL, 0);
if (IS_ERR(ibwdt_platform_device))
return PTR_ERR(ibwdt_platform_device);
err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
if (err)
goto unreg_platform_device;
return 0;
unreg_platform_device:
platform_device_unregister(ibwdt_platform_device);
return err;
}
static void __exit ibwdt_exit(void)
{
platform_device_unregister(ibwdt_platform_device);
platform_driver_unregister(&ibwdt_driver);
pr_info("Watchdog Module Unloaded\n");
}
module_init(ibwdt_init);
module_exit(ibwdt_exit);
MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
MODULE_DESCRIPTION("IB700 SBC watchdog driver");
MODULE_LICENSE("GPL");
/* end of ib700wdt.c */
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