Viewing file:  shwdt.c (7.22 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*
* drivers/char/shwdt.c
*
* Watchdog driver for integrated watchdog in the SuperH 3/4 processors.
*
* Copyright (C) 2001 Paul Mundt <lethal@chaoticdreams.org>
*
* 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.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/notifier.h>
#include <linux/smp_lock.h>
#include <linux/ioport.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#if defined(CONFIG_CPU_SH4)
#define WTCNT 0xffc00008
#define WTCSR 0xffc0000c
#elif defined(CONFIG_CPU_SH3)
#define WTCNT 0xffffff84
#define WTCSR 0xffffff86
#else
#error "Can't use SH 3/4 watchdog on non-SH 3/4 processor."
#endif
#define WTCNT_HIGH 0x5a00
#define WTCSR_HIGH 0xa500
#define WTCSR_TME 0x80
#define WTCSR_WT 0x40
#define WTCSR_RSTS 0x20
#define WTCSR_WOVF 0x10
#define WTCSR_IOVF 0x08
#define WTCSR_CKS2 0x04
#define WTCSR_CKS1 0x02
#define WTCSR_CKS0 0x01
#define WTCSR_CKS 0x07
#define WTCSR_CKS_1 0x00
#define WTCSR_CKS_4 0x01
#define WTCSR_CKS_16 0x02
#define WTCSR_CKS_32 0x03
#define WTCSR_CKS_64 0x04
#define WTCSR_CKS_256 0x05
#define WTCSR_CKS_1024 0x06
#define WTCSR_CKS_4096 0x07
static int sh_is_open = 0;
static struct watchdog_info sh_wdt_info;
/**
* sh_wdt_write_cnt - Write to Counter
*
* @val: Value to write
*
* Writes the given value @val to the lower byte of the timer counter.
* The upper byte is set manually on each write.
*/
static void sh_wdt_write_cnt(__u8 val)
{
ctrl_outw(WTCNT_HIGH | (__u16)val, WTCNT);
}
/**
* sh_wdt_write_csr - Write to Control/Status Register
*
* @val: Value to write
*
* Writes the given value @val to the lower byte of the control/status
* register. The upper byte is set manually on each write.
*/
static void sh_wdt_write_csr(__u8 val)
{
ctrl_outw(WTCSR_HIGH | (__u16)val, WTCSR);
}
/**
* sh_wdt_start - Start the Watchdog
*
* Starts the watchdog.
*/
static void sh_wdt_start(void)
{
sh_wdt_write_csr(WTCSR_WT | WTCSR_CKS_4096);
sh_wdt_write_cnt(0);
sh_wdt_write_csr((ctrl_inb(WTCSR) | WTCSR_TME));
}
/**
* sh_wdt_stop - Stop the Watchdog
*
* Stops the watchdog.
*/
static void sh_wdt_stop(void)
{
sh_wdt_write_csr((ctrl_inb(WTCSR) & ~WTCSR_TME));
}
/**
* sh_wdt_ping - Ping the Watchdog
*
* @data: Unused
*
* Clears overflow bit, resets timer counter.
*/
static void sh_wdt_ping(unsigned long data)
{
sh_wdt_write_csr((ctrl_inb(WTCSR) & ~WTCSR_IOVF));
sh_wdt_write_cnt(0);
}
/**
* sh_wdt_open - Open the Device
*
* @inode: inode of device
* @file: file handle of device
*
* Watchdog device is opened and started.
*/
static int sh_wdt_open(struct inode *inode, struct file *file)
{
switch (MINOR(inode->i_rdev)) {
case WATCHDOG_MINOR:
if (sh_is_open) {
return -EBUSY;
}
sh_is_open = 1;
sh_wdt_start();
return 0;
default:
return -ENODEV;
}
return 0;
}
/**
* sh_wdt_close - Close the Device
*
* @inode: inode of device
* @file: file handle of device
*
* Watchdog device is closed and stopped.
*/
static int sh_wdt_close(struct inode *inode, struct file *file)
{
lock_kernel();
if (MINOR(inode->i_rdev) == WATCHDOG_MINOR) {
#ifndef CONFIG_WATCHDOG_NOWAYOUT
sh_wdt_stop();
#endif
sh_is_open = 0;
}
unlock_kernel();
return 0;
}
/**
* sh_wdt_read - Read from Device
*
* @file: file handle of device
* @buf: buffer to write to
* @count: length of buffer
* @ppos: offset
*
* Unsupported.
*/
static ssize_t sh_wdt_read(struct file *file, char *buf,
size_t count, loff_t *ppos)
{
return -EINVAL;
}
/**
* sh_wdt_write - Write to Device
*
* @file: file handle of device
* @buf: buffer to write
* @count: length of buffer
* @ppos: offset
*
* Pings the watchdog on write.
*/
static ssize_t sh_wdt_write(struct file *file, const char *buf,
size_t count, loff_t *ppos)
{
/* Can't seek (pwrite) on this device */
if (ppos != &file->f_pos)
return -ESPIPE;
if (count) {
sh_wdt_ping(0);
return 1;
}
return 0;
}
/**
* sh_wdt_ioctl - Query Device
*
* @inode: inode of device
* @file: file handle of device
* @cmd: watchdog command
* @arg: argument
*
* Query basic information from the device or ping it, as outlined by the
* watchdog API.
*/
static int sh_wdt_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case WDIOC_GETSUPPORT:
if (copy_to_user((struct watchdog_info *)arg,
&sh_wdt_info,
sizeof(sh_wdt_info))) {
return -EFAULT;
}
break;
case WDIOC_GETSTATUS:
if (copy_to_user((int *)arg,
&sh_is_open,
sizeof(int))) {
return -EFAULT;
}
break;
case WDIOC_KEEPALIVE:
sh_wdt_ping(0);
break;
default:
return -ENOTTY;
}
return 0;
}
/**
* sh_wdt_notify_sys - Notifier Handler
*
* @this: notifier block
* @code: notifier event
* @unused: unused
*
* Handles specific events, such as turning off the watchdog during a
* shutdown event.
*/
static int sh_wdt_notify_sys(struct notifier_block *this,
unsigned long code, void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT) {
sh_wdt_stop();
}
return NOTIFY_DONE;
}
static struct file_operations sh_wdt_fops = {
owner: THIS_MODULE,
read: sh_wdt_read,
write: sh_wdt_write,
ioctl: sh_wdt_ioctl,
open: sh_wdt_open,
release: sh_wdt_close,
};
static struct watchdog_info sh_wdt_info = {
WDIOF_KEEPALIVEPING,
1,
"SH WDT",
};
static struct notifier_block sh_wdt_notifier = {
sh_wdt_notify_sys,
NULL,
0
};
static struct miscdevice sh_wdt_miscdev = {
WATCHDOG_MINOR,
"watchdog",
&sh_wdt_fops,
};
/**
* sh_wdt_init - Initialize module
*
* Registers the device and notifier handler. Actual device
* initialization is handled by sh_wdt_open().
*/
static int __init sh_wdt_init(void)
{
if (misc_register(&sh_wdt_miscdev)) {
printk(KERN_ERR "shwdt: Can't register misc device\n");
return -EINVAL;
}
if (!request_region(WTCNT, 1, "shwdt")) {
printk(KERN_ERR "shwdt: Can't request WTCNT region\n");
misc_deregister(&sh_wdt_miscdev);
return -ENXIO;
}
if (!request_region(WTCSR, 1, "shwdt")) {
printk(KERN_ERR "shwdt: Can't request WTCSR region\n");
release_region(WTCNT, 1);
misc_deregister(&sh_wdt_miscdev);
return -ENXIO;
}
if (register_reboot_notifier(&sh_wdt_notifier)) {
printk(KERN_ERR "shwdt: Can't register reboot notifier\n");
release_region(WTCSR, 1);
release_region(WTCNT, 1);
misc_deregister(&sh_wdt_miscdev);
return -EINVAL;
}
return 0;
}
/**
* sh_wdt_exit - Deinitialize module
*
* Unregisters the device and notifier handler. Actual device
* deinitialization is handled by sh_wdt_close().
*/
static void __exit sh_wdt_exit(void)
{
unregister_reboot_notifier(&sh_wdt_notifier);
release_region(WTCSR, 1);
release_region(WTCNT, 1);
misc_deregister(&sh_wdt_miscdev);
}
EXPORT_NO_SYMBOLS;
MODULE_AUTHOR("Paul Mundt <lethal@chaoticdreams.org>");
MODULE_DESCRIPTION("SH 3/4 watchdog driver");
MODULE_LICENSE("GPL");
module_init(sh_wdt_init);
module_exit(sh_wdt_exit);
|