// SPDX-License-Identifier: GPL-2.0-or-later
/*
* MachZ ZF-Logic Watchdog Timer driver for Linux
*
* The author does 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.
*
* Author: Fernando Fuganti <[email protected]>
*
* Based on sbc60xxwdt.c by Jakob Oestergaard
*
* We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
* following periods:
* wd#1 - 2 seconds;
* wd#2 - 7.2 ms;
* After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
* a system RESET and it starts wd#2 that unconditionally will RESET
* the system when the counter reaches zero.
*
* 14-Dec-2001 Matt Domsch <[email protected]>
* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
*/
#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>
/* ports */
#define ZF_IOBASE 0x218
#define INDEX 0x218
#define DATA_B 0x219
#define DATA_W 0x21A
#define DATA_D 0x21A
/* indexes */ /* size */
#define ZFL_VERSION 0x02 /* 16 */
#define CONTROL 0x10 /* 16 */
#define STATUS 0x12 /* 8 */
#define COUNTER_1 0x0C /* 16 */
#define COUNTER_2 0x0E /* 8 */
#define PULSE_LEN 0x0F /* 8 */
/* controls */
#define ENABLE_WD1 0x0001
#define ENABLE_WD2 0x0002
#define RESET_WD1 0x0010
#define RESET_WD2 0x0020
#define GEN_SCI 0x0100
#define GEN_NMI 0x0200
#define GEN_SMI 0x0400
#define GEN_RESET 0x0800
/* utilities */
#define WD1 0
#define WD2 1
#define zf_writew(port, data) { outb(port, INDEX); outw(data, DATA_W); }
#define zf_writeb(port, data) { outb(port, INDEX); outb(data, DATA_B); }
#define zf_get_ZFL_version() zf_readw(ZFL_VERSION)
static unsigned short zf_readw(unsigned char port)
{
outb(port, INDEX);
return inw(DATA_W);
}
MODULE_AUTHOR("Fernando Fuganti <[email protected]>");
MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
MODULE_LICENSE("GPL");
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 PFX "machzwd"
static const struct watchdog_info zf_info = {
.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
.firmware_version = 1,
.identity = "ZF-Logic watchdog",
};
/*
* action refers to action taken when watchdog resets
* 0 = GEN_RESET
* 1 = GEN_SMI
* 2 = GEN_NMI
* 3 = GEN_SCI
* defaults to GEN_RESET (0)
*/
static int action;
module_param(action, int, 0);
MODULE_PARM_DESC(action, "after watchdog resets, generate: "
"0 = RESET(*) 1 = SMI 2 = NMI 3 = SCI");
static void zf_ping(struct timer_list *unused);
static int zf_action = GEN_RESET;
static unsigned long zf_is_open;
static char zf_expect_close;
static DEFINE_SPINLOCK(zf_port_lock);
static DEFINE_TIMER(zf_timer, zf_ping);
static unsigned long next_heartbeat;
/* timeout for user land heart beat (10 seconds) */
#define ZF_USER_TIMEO (HZ*10)
/* timeout for hardware watchdog (~500ms) */
#define ZF_HW_TIMEO (HZ/2)
/* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
#define ZF_CTIMEOUT 0xffff
#ifndef ZF_DEBUG
#define dprintk(format, args...)
#else
#define dprintk(format, args...) \
pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
#endif
static inline void zf_set_status(unsigned char new)
{
zf_writeb(STATUS, new);
}
/* CONTROL register functions */
static inline unsigned short zf_get_control(void)
{
return zf_readw(CONTROL);
}
static inline void zf_set_control(unsigned short new)
{
zf_writew(CONTROL, new);
}
/* WD#? counter functions */
/*
* Just set counter value
*/
static inline void zf_set_timer(unsigned short new, unsigned char n)
{
switch (n) {
case WD1:
zf_writew(COUNTER_1, new);
fallthrough;
case WD2:
zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
fallthrough;
default:
return;
}
}
/*
* stop hardware timer
*/
static void zf_timer_off(void)
{
unsigned int ctrl_reg = 0;
unsigned long flags;
/* stop internal ping */
del_timer_sync(&zf_timer);
spin_lock_irqsave(&zf_port_lock, flags);
/* stop watchdog timer */
ctrl_reg = zf_get_control();
ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */
ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
zf_set_control(ctrl_reg);
spin_unlock_irqrestore(&zf_port_lock, flags);
pr_info("Watchdog timer is now disabled\n");
}
/*
* start hardware timer
*/
static void zf_timer_on(void)
{
unsigned int ctrl_reg = 0;
unsigned long flags;
spin_lock_irqsave(&zf_port_lock, flags);
zf_writeb(PULSE_LEN, 0xff);
zf_set_timer(ZF_CTIMEOUT, WD1);
/* user land ping */
next_heartbeat = jiffies + ZF_USER_TIMEO;
/* start the timer for internal ping */
mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
/* start watchdog timer */
ctrl_reg = zf_get_control();
ctrl_reg |= (ENABLE_WD1|zf_action);
zf_set_control(ctrl_reg);
spin_unlock_irqrestore(&zf_port_lock, flags);
pr_info("Watchdog timer is now enabled\n");
}
static void zf_ping(struct timer_list *unused)
{
unsigned int ctrl_reg = 0;
unsigned long flags;
zf_writeb(COUNTER_2, 0xff);
if (time_before(jiffies, next_heartbeat)) {
dprintk("time_before: %ld\n", next_heartbeat - jiffies);
/*
* reset event is activated by transition from 0 to 1 on
* RESET_WD1 bit and we assume that it is already zero...
*/
spin_lock_irqsave(&zf_port_lock, flags);
ctrl_reg = zf_get_control();
ctrl_reg |= RESET_WD1;
zf_set_control(ctrl_reg);
/* ...and nothing changes until here */
ctrl_reg &= ~(RESET_WD1);
zf_set_control(ctrl_reg);
spin_unlock_irqrestore(&zf_port_lock, flags);
mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
} else
pr_crit("I will reset your machine\n");
}
static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
loff_t *ppos)
{
/* See if we got the magic character */
if (count) {
/*
* no need to check for close confirmation
* no way to disable watchdog ;)
*/
if (!nowayout) {
size_t ofs;
/*
* note: just in case someone wrote the magic character
* five months ago...
*/
zf_expect_close = 0;
/* now scan */
for (ofs = 0; ofs != count; ofs++) {
char c;
if (get_user(c, buf + ofs))
return -EFAULT;
if (c == 'V') {
zf_expect_close = 42;
dprintk("zf_expect_close = 42\n");
}
}
}
/*
* Well, anyhow someone wrote to us,
* we should return that favour
*/
next_heartbeat = jiffies + ZF_USER_TIMEO;
dprintk("user ping at %ld\n", jiffies);
}
return count;
}
static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
return -EFAULT;
break;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_KEEPALIVE:
zf_ping(NULL);
break;
default:
return -ENOTTY;
}
return 0;
}
static int zf_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &zf_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
zf_timer_on();
return stream_open(inode, file);
}
static int zf_close(struct inode *inode, struct file *file)
{
if (zf_expect_close == 42)
zf_timer_off();
else {
del_timer(&zf_timer);
pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
}
clear_bit(0, &zf_is_open);
zf_expect_close = 0;
return 0;
}
/*
* Notifier for system down
*/
static int zf_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
zf_timer_off();
return NOTIFY_DONE;
}
static const struct file_operations zf_fops = {
.owner = THIS_MODULE,
.write = zf_write,
.unlocked_ioctl = zf_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = zf_open,
.release = zf_close,
};
static struct miscdevice zf_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &zf_fops,
};
/*
* The device needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block zf_notifier = {
.notifier_call = zf_notify_sys,
};
static void __init zf_show_action(int act)
{
static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
pr_info("Watchdog using action = %s\n", str[act]);
}
static int __init zf_init(void)
{
int ret;
pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
ret = zf_get_ZFL_version();
if (!ret || ret == 0xffff) {
pr_warn("no ZF-Logic found\n");
return -ENODEV;
}
if (action <= 3 && action >= 0)
zf_action = zf_action >> action;
else
action = 0;
zf_show_action(action);
if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
ret = -EBUSY;
goto no_region;
}
ret = register_reboot_notifier(&zf_notifier);
if (ret) {
pr_err("can't register reboot notifier (err=%d)\n", ret);
goto no_reboot;
}
ret = misc_register(&zf_miscdev);
if (ret) {
pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
goto no_misc;
}
zf_set_status(0);
zf_set_control(0);
return 0;
no_misc:
unregister_reboot_notifier(&zf_notifier);
no_reboot:
release_region(ZF_IOBASE, 3);
no_region:
return ret;
}
static void __exit zf_exit(void)
{
zf_timer_off();
misc_deregister(&zf_miscdev);
unregister_reboot_notifier(&zf_notifier);
release_region(ZF_IOBASE, 3);
}
module_init(zf_init);
module_exit(zf_exit);
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