/*
* SMsC 37B787 Watchdog Timer driver for Linux 2.6.x.x
*
* Based on acquirewdt.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
* and some other existing drivers
*
* 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.
*
* 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 2003-2006 Sven Anders <anders@anduras.de>
*
* History:
* 2003 - Created version 1.0 for Linux 2.4.x.
* 2006 - Ported to Linux 2.6, added nowayout and MAGICCLOSE
* features. Released version 1.1
*
* Theory of operation:
*
* A Watchdog Timer (WDT) is a hardware circuit that can
* reset the computer system in case of a software fault.
* You probably knew that already.
*
* Usually a userspace daemon will notify the kernel WDT driver
* via the /dev/watchdog special device file that userspace is
* still alive, at regular intervals. When such a notification
* occurs, the driver will usually tell the hardware watchdog
* that everything is in order, and that the watchdog should wait
* for yet another little while to reset the system.
* If userspace fails (RAM error, kernel bug, whatever), the
* notifications cease to occur, and the hardware watchdog will
* reset the system (causing a reboot) after the timeout occurs.
*
* Create device with:
* mknod /dev/watchdog c 10 130
*
* For an example userspace keep-alive daemon, see:
* Documentation/watchdog/wdt.txt
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <asm/system.h>
/* enable support for minutes as units? */
/* (does not always work correctly, so disabled by default!) */
#define SMSC_SUPPORT_MINUTES
#undef SMSC_SUPPORT_MINUTES
#define MAX_TIMEOUT 255
#define UNIT_SECOND 0
#define UNIT_MINUTE 1
#define VERSION "1.1"
#define IOPORT 0x3F0
#define IOPORT_SIZE 2
#define IODEV_NO 8
static int unit = UNIT_SECOND; /* timer's unit */
static int timeout = 60; /* timeout value: default is 60 "units" */
static unsigned long timer_enabled; /* is the timer enabled? */
static char expect_close; /* is the close expected? */
static DEFINE_SPINLOCK(io_lock);/* to guard the watchdog from io races */
static bool nowayout = WATCHDOG_NOWAYOUT;
/* -- Low level function ----------------------------------------*/
/* unlock the IO chip */
static inline void open_io_config(void)
{
outb(0x55, IOPORT);
mdelay(1);
outb(0x55, IOPORT);
}
/* lock the IO chip */
static inline void close_io_config(void)
{
outb(0xAA, IOPORT);
}
/* select the IO device */
static inline void select_io_device(unsigned char devno)
{
outb(0x07, IOPORT);
outb(devno, IOPORT+1);
}
/* write to the control register */
static inline void write_io_cr(unsigned char reg, unsigned char data)
{
outb(reg, IOPORT);
outb(data, IOPORT+1);
}
/* read from the control register */
static inline char read_io_cr(unsigned char reg)
{
outb(reg, IOPORT);
return inb(IOPORT+1);
}
/* -- Medium level functions ------------------------------------*/
static inline void gpio_bit12(unsigned char reg)
{
/* -- General Purpose I/O Bit 1.2 --
* Bit 0, In/Out: 0 = Output, 1 = Input
* Bit 1, Polarity: 0 = No Invert, 1 = Invert
* Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable
* Bit 3/4, Function select: 00 = GPI/O, 01 = WDT, 10 = P17,
* 11 = Either Edge Triggered Intr. 2
* Bit 5/6 (Reserved)
* Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain
*/
write_io_cr(0xE2, reg);
}
static inline void gpio_bit13(unsigned char reg)
{
/* -- General Purpose I/O Bit 1.3 --
* Bit 0, In/Out: 0 = Output, 1 = Input
* Bit 1, Polarity: 0 = No Invert, 1 = Invert
* Bit 2, Group Enable Intr.: 0 = Disable, 1 = Enable
* Bit 3, Function select: 0 = GPI/O, 1 = LED
* Bit 4-6 (Reserved)
* Bit 7, Output Type: 0 = Push Pull Bit, 1 = Open Drain
*/
write_io_cr(0xE3, reg);
}
static inline void wdt_timer_units(unsigned char new_units)
{
/* -- Watchdog timer units --
* Bit 0-6 (Reserved)
* Bit 7, WDT Time-out Value Units Select
* (0 = Minutes, 1 = Seconds)
*/
write_io_cr(0xF1, new_units);
}
static inline void wdt_timeout_value(unsigned char new_timeout)
{
/* -- Watchdog Timer Time-out Value --
* Bit 0-7 Binary coded units (0=Disabled, 1..255)
*/
write_io_cr(0xF2, new_timeout);
}
static inline void wdt_timer_conf(unsigned char conf)
{
/* -- Watchdog timer configuration --
* Bit 0 Joystick enable: 0* = No Reset, 1 = Reset WDT upon
* Gameport I/O
* Bit 1 Keyboard enable: 0* = No Reset, 1 = Reset WDT upon KBD Intr.
* Bit 2 Mouse enable: 0* = No Reset, 1 = Reset WDT upon Mouse Intr
* Bit 3 Reset the timer
* (Wrong in SMsC documentation? Given as: PowerLED Timout
* Enabled)
* Bit 4-7 WDT Interrupt Mapping: (0000* = Disabled,
* 0001=IRQ1, 0010=(Invalid), 0011=IRQ3 to 1111=IRQ15)
*/
write_io_cr(0xF3, conf);
}
static inline void wdt_timer_ctrl(unsigned char reg)
{
/* -- Watchdog timer control --
* Bit 0 Status Bit: 0 = Timer counting, 1 = Timeout occurred
* Bit 1 Power LED Toggle: 0 = Disable Toggle, 1 = Toggle at 1 Hz
* Bit 2 Force Timeout: 1 = Forces WD timeout event (self-cleaning)
* Bit 3 P20 Force Timeout enabled:
* 0 = P20 activity does not generate the WD timeout event
* 1 = P20 Allows rising edge of P20, from the keyboard
* controller, to force the WD timeout event.
* Bit 4 (Reserved)
* -- Soft power management --
* Bit 5 Stop Counter: 1 = Stop software power down counter
* set via register 0xB8, (self-cleaning)
* (Upon read: 0 = Counter running, 1 = Counter stopped)
* Bit 6 Restart Counter: 1 = Restart software power down counter
* set via register 0xB8, (self-cleaning)
* Bit 7 SPOFF: 1 = Force software power down (self-cleaning)
*/
write_io_cr(0xF4, reg);
}
/* -- Higher level functions ------------------------------------*/
/* initialize watchdog */
static void wb_smsc_wdt_initialize(void)
{
unsigned char old;
spin_lock(&io_lock);
open_io_config();
select_io_device(IODEV_NO);
/* enable the watchdog */
gpio_bit13(0x08); /* Select pin 80 = LED not GPIO */
gpio_bit12(0x0A); /* Set pin 79 = WDT not
GPIO/Output/Polarity=Invert */
/* disable the timeout */
wdt_timeout_value(0);
/* reset control register */
wdt_timer_ctrl(0x00);
/* reset configuration register */
wdt_timer_conf(0x00);
/* read old (timer units) register */
old = read_io_cr(0xF1) & 0x7F;
if (unit == UNIT_SECOND)
old |= 0x80; /* set to seconds */
/* set the watchdog timer units */
wdt_timer_units(old);
close_io_config();
spin_unlock(&io_lock);
}
/* shutdown the watchdog */
static void wb_smsc_wdt_shutdown(void)
{
spin_lock(&io_lock);
open_io_config();
select_io_device(IODEV_NO);
/* disable the watchdog */
gpio_bit13(0x09);
gpio_bit12(0x09);
/* reset watchdog config register */
wdt_timer_conf(0x00);
/* reset watchdog control register */
wdt_timer_ctrl(0x00);
/* disable timeout */
wdt_timeout_value(0x00);
close_io_config();
spin_unlock(&io_lock);
}
/* set timeout => enable watchdog */
static void wb_smsc_wdt_set_timeout(unsigned char new_timeout)
{
spin_lock(&io_lock);
open_io_config();
select_io_device(IODEV_NO);
/* set Power LED to blink, if we enable the timeout */
wdt_timer_ctrl((new_timeout == 0) ? 0x00 : 0x02);
/* set timeout value */
wdt_timeout_value(new_timeout);
close_io_config();
spin_unlock(&io_lock);
}
/* get timeout */
static unsigned char wb_smsc_wdt_get_timeout(void)
{
unsigned char set_timeout;
spin_lock(&io_lock);
open_io_config();
select_io_device(IODEV_NO);
set_timeout = read_io_cr(0xF2);
close_io_config();
spin_unlock(&io_lock);
return set_timeout;
}
/* disable watchdog */
static void wb_smsc_wdt_disable(void)
{
/* set the timeout to 0 to disable the watchdog */
wb_smsc_wdt_set_timeout(0);
}
/* enable watchdog by setting the current timeout */
static void wb_smsc_wdt_enable(void)
{
/* set the current timeout... */
wb_smsc_wdt_set_timeout(timeout);
}
/* reset the timer */
static void wb_smsc_wdt_reset_timer(void)
{
spin_lock(&io_lock);
open_io_config();
select_io_device(IODEV_NO);
/* reset the timer */
wdt_timeout_value(timeout);
wdt_timer_conf(0x08);
close_io_config();
spin_unlock(&io_lock);
}
/* return, if the watchdog is enabled (timeout is set...) */
static int wb_smsc_wdt_status(void)
{
return (wb_smsc_wdt_get_timeout() == 0) ? 0 : WDIOF_KEEPALIVEPING;
}
/* -- File operations -------------------------------------------*/
/* open => enable watchdog and set initial timeout */
static int wb_smsc_wdt_open(struct inode *inode, struct file *file)
{
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &timer_enabled))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Reload and activate timer */
wb_smsc_wdt_enable();
pr_info("Watchdog enabled. Timeout set to %d %s\n",
timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
return nonseekable_open(inode, file);
}
/* close => shut off the timer */
static int wb_smsc_wdt_release(struct inode *inode, struct file *file)
{
/* Shut off the timer. */
if (expect_close == 42) {
wb_smsc_wdt_disable();
pr_info("Watchdog disabled, sleeping again...\n");
} else {
pr_crit("Unexpected close, not stopping watchdog!\n");
wb_smsc_wdt_reset_timer();
}
clear_bit(0, &timer_enabled);
expect_close = 0;
return 0;
}
/* write => update the timer to keep the machine alive */
static ssize_t wb_smsc_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (len) {
if (!nowayout) {
size_t i;
/* reset expect flag */
expect_close = 0;
/* scan to see whether or not we got the
magic character */
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
expect_close = 42;
}
}
/* someone wrote to us, we should reload the timer */
wb_smsc_wdt_reset_timer();
}
return len;
}
/* ioctl => control interface */
static long wb_smsc_wdt_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
int new_timeout;
union {
struct watchdog_info __user *ident;
int __user *i;
} uarg;
static const struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = "SMsC 37B787 Watchdog",
};
uarg.i = (int __user *)arg;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(uarg.ident, &ident, sizeof(ident))
? -EFAULT : 0;
case WDIOC_GETSTATUS:
return put_user(wb_smsc_wdt_status(), uarg.i);
case WDIOC_GETBOOTSTATUS:
return put_user(0, uarg.i);
case WDIOC_SETOPTIONS:
{
int options, retval = -EINVAL;
if (get_user(options, uarg.i))
return -EFAULT;
if (options & WDIOS_DISABLECARD) {
wb_smsc_wdt_disable();
retval = 0;
}
if (options & WDIOS_ENABLECARD) {
wb_smsc_wdt_enable();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
wb_smsc_wdt_reset_timer();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_timeout, uarg.i))
return -EFAULT;
/* the API states this is given in secs */
if (unit == UNIT_MINUTE)
new_timeout /= 60;
if (new_timeout < 0 || new_timeout > MAX_TIMEOUT)
return -EINVAL;
timeout = new_timeout;
wb_smsc_wdt_set_timeout(timeout);
/* fall through and return the new timeout... */
case WDIOC_GETTIMEOUT:
new_timeout = timeout;
if (unit == UNIT_MINUTE)
new_timeout *= 60;
return put_user(new_timeout, uarg.i);
default:
return -ENOTTY;
}
}
/* -- Notifier funtions -----------------------------------------*/
static int wb_smsc_wdt_notify_sys(struct notifier_block *this,
unsigned long code, void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT) {
/* set timeout to 0, to avoid possible race-condition */
timeout = 0;
wb_smsc_wdt_disable();
}
return NOTIFY_DONE;
}
/* -- Module's structures ---------------------------------------*/
static const struct file_operations wb_smsc_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = wb_smsc_wdt_write,
.unlocked_ioctl = wb_smsc_wdt_ioctl,
.open = wb_smsc_wdt_open,
.release = wb_smsc_wdt_release,
};
static struct notifier_block wb_smsc_wdt_notifier = {
.notifier_call = wb_smsc_wdt_notify_sys,
};
static struct miscdevice wb_smsc_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wb_smsc_wdt_fops,
};
/* -- Module init functions -------------------------------------*/
/* module's "constructor" */
static int __init wb_smsc_wdt_init(void)
{
int ret;
pr_info("SMsC 37B787 watchdog component driver "
VERSION " initialising...\n");
if (!request_region(IOPORT, IOPORT_SIZE, "SMsC 37B787 watchdog")) {
pr_err("Unable to register IO port %#x\n", IOPORT);
ret = -EBUSY;
goto out_pnp;
}
/* set new maximum, if it's too big */
if (timeout > MAX_TIMEOUT)
timeout = MAX_TIMEOUT;
/* init the watchdog timer */
wb_smsc_wdt_initialize();
ret = register_reboot_notifier(&wb_smsc_wdt_notifier);
if (ret) {
pr_err("Unable to register reboot notifier err = %d\n", ret);
goto out_io;
}
ret = misc_register(&wb_smsc_wdt_miscdev);
if (ret) {
pr_err("Unable to register miscdev on minor %d\n",
WATCHDOG_MINOR);
goto out_rbt;
}
/* output info */
pr_info("Timeout set to %d %s\n",
timeout, (unit == UNIT_SECOND) ? "second(s)" : "minute(s)");
pr_info("Watchdog initialized and sleeping (nowayout=%d)...\n",
nowayout);
out_clean:
return ret;
out_rbt:
unregister_reboot_notifier(&wb_smsc_wdt_notifier);
out_io:
release_region(IOPORT, IOPORT_SIZE);
out_pnp:
goto out_clean;
}
/* module's "destructor" */
static void __exit wb_smsc_wdt_exit(void)
{
/* Stop the timer before we leave */
if (!nowayout) {
wb_smsc_wdt_shutdown();
pr_info("Watchdog disabled\n");
}
misc_deregister(&wb_smsc_wdt_miscdev);
unregister_reboot_notifier(&wb_smsc_wdt_notifier);
release_region(IOPORT, IOPORT_SIZE);
pr_info("SMsC 37B787 watchdog component driver removed\n");
}
module_init(wb_smsc_wdt_init);
module_exit(wb_smsc_wdt_exit);
MODULE_AUTHOR("Sven Anders <anders@anduras.de>");
MODULE_DESCRIPTION("Driver for SMsC 37B787 watchdog component (Version "
VERSION ")");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
#ifdef SMSC_SUPPORT_MINUTES
module_param(unit, int, 0);
MODULE_PARM_DESC(unit,
"set unit to use, 0=seconds or 1=minutes, default is 0");
#endif
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "range is 1-255 units, default is 60");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
