// SPDX-License-Identifier: GPL-2.0-or-later
/*
* W83877F Computer Watchdog Timer driver
*
* Based on acquirewdt.c by Alan Cox,
* and sbc60xxwdt.c by Jakob Oestergaard <[email protected]>
*
* The authors do NOT admit liability nor provide warranty for
* any of this software. This material is provided "AS-IS" in
* the hope that it may be useful for others.
*
* (c) Copyright 2001 Scott Jennings <[email protected]>
*
* 4/19 - 2001 [Initial revision]
* 9/27 - 2001 Added spinlocking
* 4/12 - 2002 [[email protected]] Eliminate extra comments
* Eliminate fop_read
* Eliminate extra spin_unlock
* Added KERN_* tags to printks
* add CONFIG_WATCHDOG_NOWAYOUT support
* fix possible wdt_is_open race
* changed watchdog_info to correctly reflect what
* the driver offers
* added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
* WDIOC_SETTIMEOUT,
* WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
* 09/8 - 2003 [[email protected]] cleanup of trailing spaces
* added extra printk's for startup problems
* use module_param
* made timeout (the emulated heartbeat) a
* module_param
* made the keepalive ping an internal subroutine
*
* This WDT driver is different from most other Linux WDT
* drivers in that the driver will ping the watchdog by itself,
* because this particular WDT has a very short timeout (1.6
* seconds) and it would be insane to count on any userspace
* daemon always getting scheduled within that time frame.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/jiffies.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 <linux/io.h>
#include <linux/uaccess.h>
#define OUR_NAME "w83877f_wdt"
#define ENABLE_W83877F_PORT 0x3F0
#define ENABLE_W83877F 0x87
#define DISABLE_W83877F 0xAA
#define WDT_PING 0x443
#define WDT_REGISTER 0x14
#define WDT_ENABLE 0x9C
#define WDT_DISABLE 0x8C
/*
* The W83877F seems to be fixed at 1.6s timeout (at least on the
* EMACS PC-104 board I'm using). If we reset the watchdog every
* ~250ms we should be safe. */
#define WDT_INTERVAL (HZ/4+1)
/*
* We must not require too good response from the userspace daemon.
* Here we require the userspace daemon to send us a heartbeat
* char to /dev/watchdog every 30 seconds.
*/
#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. (1<=timeout<=3600, 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) ")");
static void wdt_timer_ping(struct timer_list *);
static DEFINE_TIMER(timer, wdt_timer_ping);
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
static DEFINE_SPINLOCK(wdt_spinlock);
/*
* Whack the dog
*/
static void wdt_timer_ping(struct timer_list *unused)
{
/* If we got a heartbeat pulse within the WDT_US_INTERVAL
* we agree to ping the WDT
*/
if (time_before(jiffies, next_heartbeat)) {
/* Ping the WDT */
spin_lock(&wdt_spinlock);
/* Ping the WDT by reading from WDT_PING */
inb_p(WDT_PING);
/* Re-set the timer interval */
mod_timer(&timer, jiffies + WDT_INTERVAL);
spin_unlock(&wdt_spinlock);
} else
pr_warn("Heartbeat lost! Will not ping the watchdog\n");
}
/*
* Utility routines
*/
static void wdt_change(int writeval)
{
unsigned long flags;
spin_lock_irqsave(&wdt_spinlock, flags);
/* buy some time */
inb_p(WDT_PING);
/* make W83877F available */
outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);
outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);
/* enable watchdog */
outb_p(WDT_REGISTER, ENABLE_W83877F_PORT);
outb_p(writeval, ENABLE_W83877F_PORT+1);
/* lock the W8387FF away */
outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
spin_unlock_irqrestore(&wdt_spinlock, flags);
}
static void wdt_startup(void)
{
next_heartbeat = jiffies + (timeout * HZ);
/* Start the timer */
mod_timer(&timer, jiffies + WDT_INTERVAL);
wdt_change(WDT_ENABLE);
pr_info("Watchdog timer is now enabled\n");
}
static void wdt_turnoff(void)
{
/* Stop the timer */
del_timer_sync(&timer);
wdt_change(WDT_DISABLE);
pr_info("Watchdog timer is now disabled...\n");
}
static void wdt_keepalive(void)
{
/* user land ping */
next_heartbeat = jiffies + (timeout * HZ);
}
/*
* /dev/watchdog handling
*/
static ssize_t fop_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 ofs;
/* note: just in case someone wrote the magic
character five months ago... */
wdt_expect_close = 0;
/* scan to see whether or not we got the
magic character */
for (ofs = 0; ofs != count; ofs++) {
char c;
if (get_user(c, buf + ofs))
return -EFAULT;
if (c == 'V')
wdt_expect_close = 42;
}
}
/* someone wrote to us, we should restart timer */
wdt_keepalive();
}
return count;
}
static int fop_open(struct inode *inode, struct file *file)
{
/* Just in case we're already talking to someone... */
if (test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
/* Good, fire up the show */
wdt_startup();
return stream_open(inode, file);
}
static int fop_close(struct inode *inode, struct file *file)
{
if (wdt_expect_close == 42)
wdt_turnoff();
else {
del_timer(&timer);
pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
}
clear_bit(0, &wdt_is_open);
wdt_expect_close = 0;
return 0;
}
static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
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 = "W83877F",
};
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_SETOPTIONS:
{
int new_options, retval = -EINVAL;
if (get_user(new_options, p))
return -EFAULT;
if (new_options & WDIOS_DISABLECARD) {
wdt_turnoff();
retval = 0;
}
if (new_options & WDIOS_ENABLECARD) {
wdt_startup();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
wdt_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
{
int new_timeout;
if (get_user(new_timeout, p))
return -EFAULT;
/* arbitrary upper limit */
if (new_timeout < 1 || new_timeout > 3600)
return -EINVAL;
timeout = new_timeout;
wdt_keepalive();
}
fallthrough;
case WDIOC_GETTIMEOUT:
return put_user(timeout, p);
default:
return -ENOTTY;
}
}
static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.write = fop_write,
.open = fop_open,
.release = fop_close,
.unlocked_ioctl = fop_ioctl,
.compat_ioctl = compat_ptr_ioctl,
};
static struct miscdevice wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wdt_fops,
};
/*
* Notifier for system down
*/
static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
wdt_turnoff();
return NOTIFY_DONE;
}
/*
* The WDT needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block wdt_notifier = {
.notifier_call = wdt_notify_sys,
};
static void __exit w83877f_wdt_unload(void)
{
wdt_turnoff();
/* Deregister */
misc_deregister(&wdt_miscdev);
unregister_reboot_notifier(&wdt_notifier);
release_region(WDT_PING, 1);
release_region(ENABLE_W83877F_PORT, 2);
}
static int __init w83877f_wdt_init(void)
{
int rc = -EBUSY;
if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
timeout = WATCHDOG_TIMEOUT;
pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
timeout);
}
if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
pr_err("I/O address 0x%04x already in use\n",
ENABLE_W83877F_PORT);
rc = -EIO;
goto err_out;
}
if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
pr_err("I/O address 0x%04x already in use\n", WDT_PING);
rc = -EIO;
goto err_out_region1;
}
rc = register_reboot_notifier(&wdt_notifier);
if (rc) {
pr_err("cannot register reboot notifier (err=%d)\n", rc);
goto err_out_region2;
}
rc = misc_register(&wdt_miscdev);
if (rc) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
wdt_miscdev.minor, rc);
goto err_out_reboot;
}
pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
timeout, nowayout);
return 0;
err_out_reboot:
unregister_reboot_notifier(&wdt_notifier);
err_out_region2:
release_region(WDT_PING, 1);
err_out_region1:
release_region(ENABLE_W83877F_PORT, 2);
err_out:
return rc;
}
module_init(w83877f_wdt_init);
module_exit(w83877f_wdt_unload);
MODULE_AUTHOR("Scott and Bill Jennings");
MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
MODULE_LICENSE("GPL");
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