omap_wdt_core.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 238 行

/* 
 * linux/drivers/char/watchdog/omap_wdt_core.c
 * 
 * Watchdog driver for the TI OMAP 1610, 1710 & 24xx
 *
 * Copyright (C) 2004 Texas Instruments, Inc. 
 * 
 * This package is free software; you can redistribute it and/or modify 
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation. 
 * 
 * THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 
 */

/************************ INCLUDES ****************************************/

#include <linux/module.h>
#include <linux/config.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/reboot.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>
#include <asm/bitops.h>
#include <asm/io.h>
#include <asm/hardware/clock.h>

#include <linux/moduleparam.h>
#include <linux/delay.h>
#include "omap_wdt_core.h"
#include "omap_wdt_hardware.h"

/************************ DEFINES *****************************************/

#define WATCHDOG_NAME  "OMAP Watchdog"

/************************ FUNCTION PROTOTYPES *****************************/

static int omap_wdt_open(struct inode *inode, struct file *file);
static int omap_wdt_release(struct inode *inode, struct file *file);
static ssize_t omap_wdt_write(struct file *file, const char *data, size_t len,
			      loff_t * ppos);
static int omap_wdt_ioctl(struct inode *inode, struct file *file,
			  unsigned int cmd, unsigned long arg);

/************************ DATA STRUCTURES *********************************/

/* Current WDT timeout value in second */
static int timer_margin;

/* Flag to allow only one user acces to driver*/
static char omap_wdt_users;

/* File Operations Structure */
struct file_operations omap_wdt_fops = {
	.owner 		= THIS_MODULE,
	.write 		= omap_wdt_write,
	.ioctl 		= omap_wdt_ioctl,
	.open 		= omap_wdt_open,
	.release 	= omap_wdt_release,
};

/* Device Structure */
static struct miscdevice omap_wdt_miscdev = {
	.minor 	= WATCHDOG_MINOR,
	.name 	= "omap_wdt",
	.fops 	= &omap_wdt_fops
};

/************************ FUNCTION DEFINTIONS *****************************/

/* omap_wdt_open(): Driver open function */
static int omap_wdt_open(struct inode *inode, struct file *file)
{
	/* Allow only one person to hold it open at any given time */
	if (test_and_set_bit(1, (unsigned long *)&omap_wdt_users))
		return -EBUSY;


	omap_wdt_enable();

	return 0;
}

/* omap_wdt_release(): Driver release function */
static int omap_wdt_release(struct inode *inode, struct file *file)
{
	/*
	 * Shut off the timer.
	 * Lock it in if it's a module and we defined ...NOWAYOUT
	 */
#ifndef CONFIG_WATCHDOG_NOWAYOUT
	omap_wdt_disable();
	WDT_CK_DISABLE();	/* Disable the clock */

#endif				/* CONFIG_WATCHDOG_NOWAYOUT */

	omap_wdt_users = 0;

	return 0;
}

/* omap_wdt_write(): Driver write function 
 * A write with a non zero length data would refresh the watchdog counter
 */
static ssize_t
omap_wdt_write(struct file *file, const char *data, size_t len, loff_t * ppos)
{
	/*  Can't seek (pwrite) on this device  */
	if (*ppos != file->f_pos) {
		printk(KERN_ERR "%s: f_pos!=ppos\n", __FUNCTION__);
		return -ESPIPE;
	}

	/* Refresh the watchdog */
	if (len) {
		omap_wdt_ping();
		return 1;
	}
	return 0;
}

/* omap_wdt_ioctl(): Driver ioctl function 
 */
static int
omap_wdt_ioctl(struct inode *inode, struct file *file,
	       unsigned int cmd, unsigned long arg)
{
	int new_margin,min_margin,max_margin;
	int ret = -ENOIOCTLCMD;
	static struct watchdog_info ident = {
		.identity 		= WATCHDOG_NAME,
		.options 		= OPTIONS,
		.firmware_version 	= 0,
	};

	switch (cmd) {

	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info *)arg, &ident,
				   sizeof(ident));
		break;

	case WDIOC_GETSTATUS:
		ret = put_user(0, (int *)arg);
		break;

	case WDIOC_GETBOOTSTATUS:
		ret = put_user(omap_wdt_boot_status(), (int *)arg);
		break;

	case WDIOC_KEEPALIVE:
		omap_wdt_ping();
		ret = 0;
		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, (int *)arg)) {
			printk(KERN_ERR
			       "%s: WDIOC_SETTIMEOUT: Unable to read user space\n",
			       __FUNCTION__);
			return -EFAULT;
		}
		omap_wdt_get_time_margin(&min_margin, &max_margin);
		if ((new_margin < min_margin)
		    || (new_margin > max_margin))
		{
			/* default timeoout */
			timer_margin = max_margin;
		}
		else
		{
			timer_margin = new_margin;
		}
		
		omap_wdt_disable();

		omap_wldr_write(timer_margin);

		omap_wdt_enable();

		omap_wdt_ping();

		/* Fall through */

	case WDIOC_GETTIMEOUT:
		ret = put_user(timer_margin, (int *)arg);
		break;

	default:
		break;
	}

	return ret;
}

/* omap_wdt_init: Driver init function */
static int __init omap_wdt_init(void)
{
	int ret;

	ret = misc_register(&omap_wdt_miscdev);

	if (ret) {
		printk(KERN_ERR WATCHDOG_NAME
		       ": Failed to register with Misc (%d)\n", ret);
		return ret;
	}
	omap_wdt_start(timer_margin);

	printk(KERN_INFO
	       "%s: TI OMAP Watchdog Timer: timer margin %d sec\n",
	       omap_wdt_miscdev.name, timer_margin);

	return 0;
}

/* omap_wdt_exit: Driver init function */
static void __exit omap_wdt_exit(void)
{
	misc_deregister(&omap_wdt_miscdev);
}

module_init(omap_wdt_init);
module_exit(omap_wdt_exit);

MODULE_AUTHOR("George G. Davis");
MODULE_LICENSE("GPL");
module_param(timer_margin, int, 0);