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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* SBC EPX C3 0.1 A Hardware Watchdog Device for the Winsystems EPX-C3
* single board computer
*
* (c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
* Reserved.
*
* based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/uaccess.h>
#include <linux/io.h>
static int epx_c3_alive;
#define WATCHDOG_TIMEOUT 1 /* 1 sec default 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) ")");
#define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
#define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
static void epx_c3_start(void)
{
outb(1, EPXC3_WATCHDOG_CTL_REG);
}
static void epx_c3_stop(void)
{
outb(0, EPXC3_WATCHDOG_CTL_REG);
pr_info("Stopped watchdog timer\n");
}
static void epx_c3_pet(void)
{
outb(1, EPXC3_WATCHDOG_PET_REG);
}
/*
* Allow only one person to hold it open
*/
static int epx_c3_open(struct inode *inode, struct file *file)
{
if (epx_c3_alive)
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Activate timer */
epx_c3_start();
epx_c3_pet();
epx_c3_alive = 1;
pr_info("Started watchdog timer\n");
return stream_open(inode, file);
}
static int epx_c3_release(struct inode *inode, struct file *file)
{
/* Shut off the timer.
* Lock it in if it's a module and we defined ...NOWAYOUT */
if (!nowayout)
epx_c3_stop(); /* Turn the WDT off */
epx_c3_alive = 0;
return 0;
}
static ssize_t epx_c3_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/* Refresh the timer. */
if (len)
epx_c3_pet();
return len;
}
static long epx_c3_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
int options, retval = -EINVAL;
int __user *argp = (void __user *)arg;
static const struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING,
.firmware_version = 0,
.identity = "Winsystems EPX-C3 H/W Watchdog",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &ident, sizeof(ident)))
return -EFAULT;
return 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, argp);
case WDIOC_SETOPTIONS:
if (get_user(options, argp))
return -EFAULT;
if (options & WDIOS_DISABLECARD) {
epx_c3_stop();
retval = 0;
}
if (options & WDIOS_ENABLECARD) {
epx_c3_start();
retval = 0;
}
return retval;
case WDIOC_KEEPALIVE:
epx_c3_pet();
return 0;
case WDIOC_GETTIMEOUT:
return put_user(WATCHDOG_TIMEOUT, argp);
default:
return -ENOTTY;
}
}
static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
epx_c3_stop(); /* Turn the WDT off */
return NOTIFY_DONE;
}
static const struct file_operations epx_c3_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = epx_c3_write,
.unlocked_ioctl = epx_c3_ioctl,
.open = epx_c3_open,
.release = epx_c3_release,
};
static struct miscdevice epx_c3_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &epx_c3_fops,
};
static struct notifier_block epx_c3_notifier = {
.notifier_call = epx_c3_notify_sys,
};
static int __init watchdog_init(void)
{
int ret;
if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
return -EBUSY;
ret = register_reboot_notifier(&epx_c3_notifier);
if (ret) {
pr_err("cannot register reboot notifier (err=%d)\n", ret);
goto out;
}
ret = misc_register(&epx_c3_miscdev);
if (ret) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
unregister_reboot_notifier(&epx_c3_notifier);
goto out;
}
pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
return 0;
out:
release_region(EPXC3_WATCHDOG_CTL_REG, 2);
return ret;
}
static void __exit watchdog_exit(void)
{
misc_deregister(&epx_c3_miscdev);
unregister_reboot_notifier(&epx_c3_notifier);
release_region(EPXC3_WATCHDOG_CTL_REG, 2);
}
module_init(watchdog_init);
module_exit(watchdog_exit);
MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC. "
"Note that there is no way to probe for this device -- "
"so only use it if you are *sure* you are running on this specific "
"SBC system from Winsystems! It writes to IO ports 0x1ee and 0x1ef!");
MODULE_LICENSE("GPL");
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