m3352linux内核中看门狗喂狗和应用层喂狗方法

1、linux内核模块喂狗方法：

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <asm/mach/arch.h>
#include <mach/hardware.h>
#include <mach/gpio.h>

struct timer_list epc_watchdog;

void epc_feed_wdt(void)
{
	gpio_direction_output(65, 0);
	ndelay(2);
	gpio_direction_output(65, 1);
}
EXPORT_SYMBOL(epc_feed_wdt);

static void epc_watchdog_timeout(unsigned long arg)
{
	//printk("timer out!\n");
	epc_feed_wdt();	
	mod_timer(&epc_watchdog, jiffies + 1*HZ/4);
}

static int epc_timer_init(void)
{	
	epc_feed_wdt();
	printk("wdt feed timer start!!\n");
	init_timer(&epc_watchdog);
	epc_watchdog.function = &epc_watchdog_timeout;
	epc_watchdog.expires = jiffies + 1*HZ/4;
	add_timer(&epc_watchdog);
	epc_feed_wdt();

	return 0;
}

//static void epc_timer_exit(void)
//{
//	printk(KERN_ALERT "Goodbye, cruel world\n");
//}

subsys_initcall(epc_timer_init);
//module_init(epc_timer_init);
//module_exit(epc_timer_exit);

MODULE_LICENSE("Dual BSD/GPL");
           

2、应用层喂狗方法：

M335x-T/A3352-T工控主板有一个可编程看门狗（/dev/watchdog），可用于监测应用程序的运行状况。看门狗有如下特点：

  （1）默认超时时间为19秒，超时时间可设置（1~60秒）；

  （2）先向看门狗发送一个字符“V”后，可关闭看门狗。

设置看门狗时间

  看门狗默认超时时间为19秒，用户可以将超时时间设置为需要的值，通过ioctl实现，具体命令为：WDIOC_SETTIMEOUT，需要一个参数，即超时时间。使用示例：

int timeout = 10;
ioctl(wdt_fd, WDIOC_SETTIMEOUT, &timeout);
           

获取超时时间

  通过ioctl以及WDIOC_GETTIMEOUT命令，可以获得看门狗的超时时间。使用示例：

timeout = 0;
ioctl(wdt_fd, WDIOC_GETTIMEOUT, &timeout);
printf("The timeout is %d seconds\n", timeout);
           

喂狗操作

  看门狗被打开后，必须在超时时间内进行喂狗，最简单的喂狗办法就是向看门狗写一个字符（特殊字符除外）。

关闭看门狗

  需先写入“V”，然后使用close关闭看门狗。使用示例：

write(wdt_fd, "V", 1);
close(wdt_fd);
           

范例

  程序清单1 是一个非常简单的范例。打开看门狗后，将看门狗超时设置为10秒钟，然后在超时时间内周期性喂狗。运行该程序，系统不会复位。如果调整喂狗周期大于10秒，程序将会引起系统复位。

程序清单1  看门狗用法简单范例

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/watchdog.h>
#define WDT "/dev/watchdog"
int main(void)
{
    int wdt_fd = -1;
    int timeout;
    wdt_fd = open(WDT, O_WRONLY);
    if (wdt_fd == -1)  {
        printf("fail to open "WDT "!\n");
    }
    printf(WDT " is opened!\n");
    timeout = 10;
    ioctl(wdt_fd, WDIOC_SETTIMEOUT, &timeout);
    ioctl(wdt_fd, WDIOC_GETTIMEOUT, &timeout);
    printf("The timeout was is %d seconds\n", timeout);
#if 1                                         // 循环喂狗
    while(1)  {
        write(wdt_fd, "\0", 1);
sleep(9);    // 喂狗时间为9秒，小于设定的10秒；如果喂// 狗时间大于超时时间，将会发生看门狗复位
}
#else                                          // 关闭看门狗
   write(wdt_fd, "V", 1);
    close(wdt_fd);
    printf( WDT " is closeed!\n");
#endif
    return 0;
}
           

 3、驱动程序代码：

/*
 * omap_wdt.c
 *
 * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
 *
 * Author: MontaVista Software, Inc.
 *	 <[email protected]> or <[email protected]>
 *
 * 2003 (c) MontaVista Software, Inc. This file is licensed under the
 * terms of the GNU General Public License version 2. This program is
 * licensed "as is" without any warranty of any kind, whether express
 * or implied.
 *
 * History:
 *
 * 20030527: George G. Davis <[email protected]>
 *	Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
 *	(c) Copyright 2000 Oleg Drokin <[email protected]>
 *	Based on SoftDog driver by Alan Cox <[email protected]>
 *
 * Copyright (c) 2004 Texas Instruments.
 *	1. Modified to support OMAP1610 32-KHz watchdog timer
 *	2. Ported to 2.6 kernel
 *
 * Copyright (c) 2005 David Brownell
 *	Use the driver model and standard identifiers; handle bigger timeouts.
 */

#include <linux/module.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/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/moduleparam.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <mach/hardware.h>
#include <plat/prcm.h>

#include "omap_wdt.h"

static struct platform_device *omap_wdt_dev;

static unsigned timer_margin;
module_param(timer_margin, uint, 0);
MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

static unsigned int wdt_trgr_pattern = 0x1234;
static spinlock_t wdt_lock;

struct omap_wdt_dev {
	void __iomem    *base;          /* physical */
	struct device   *dev;
	int             omap_wdt_users;
	struct resource *mem;
	struct miscdevice omap_wdt_miscdev;
};

static void omap_wdt_ping(struct omap_wdt_dev *wdev)
{
	void __iomem    *base = wdev->base;

	/* wait for posted write to complete */
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
		cpu_relax();

	wdt_trgr_pattern = ~wdt_trgr_pattern;
	__raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

	/* wait for posted write to complete */
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
		cpu_relax();
	/* reloaded WCRR from WLDR */
}

static void omap_wdt_enable(struct omap_wdt_dev *wdev)
{
	void __iomem *base = wdev->base;

	/* Sequence to enable the watchdog */
	__raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
		cpu_relax();

	__raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
		cpu_relax();
}

static void omap_wdt_disable(struct omap_wdt_dev *wdev)
{
	void __iomem *base = wdev->base;

	/* sequence required to disable watchdog */
	__raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
		cpu_relax();

	__raw_writel(0x5555, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
		cpu_relax();
}

static void omap_wdt_adjust_timeout(unsigned new_timeout)
{
	if (new_timeout < TIMER_MARGIN_MIN)
		new_timeout = TIMER_MARGIN_DEFAULT;
	if (new_timeout > TIMER_MARGIN_MAX)
		new_timeout = TIMER_MARGIN_MAX;
	timer_margin = new_timeout;
}

static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
{
	u32 pre_margin = GET_WLDR_VAL(timer_margin);
	void __iomem *base = wdev->base;

	/* just count up at 32 KHz */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
		cpu_relax();

	__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
		cpu_relax();
}

/*
 *	Allow only one task to hold it open
 */
static int omap_wdt_open(struct inode *inode, struct file *file)
{
	struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
	void __iomem *base = wdev->base;

	if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
		return -EBUSY;

	pm_runtime_get_sync(wdev->dev);

	/* initialize prescaler */
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
		cpu_relax();

	__raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
		cpu_relax();

	file->private_data = (void *) wdev;

	omap_wdt_set_timeout(wdev);
	omap_wdt_ping(wdev); /* trigger loading of new timeout value */
	omap_wdt_enable(wdev);

	return nonseekable_open(inode, file);
}

static int omap_wdt_release(struct inode *inode, struct file *file)
{
	struct omap_wdt_dev *wdev = file->private_data;

	/*
	 *      Shut off the timer unless NOWAYOUT is defined.
	 */
#ifndef CONFIG_WATCHDOG_NOWAYOUT
	omap_wdt_disable(wdev);

	pm_runtime_put_sync(wdev->dev);
#else
	printk(KERN_CRIT "omap_wdt: Unexpected close, not stopping!\n");
#endif
	wdev->omap_wdt_users = 0;

	return 0;
}

static ssize_t omap_wdt_write(struct file *file, const char __user *data,
		size_t len, loff_t *ppos)
{
	struct omap_wdt_dev *wdev = file->private_data;

	/* Refresh LOAD_TIME. */
	if (len) {
		spin_lock(&wdt_lock);
		omap_wdt_ping(wdev);
		spin_unlock(&wdt_lock);
	}
	return len;
}

static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
						unsigned long arg)
{
	struct omap_wdt_dev *wdev;
	int new_margin;
	static const struct watchdog_info ident = {
		.identity = "OMAP Watchdog",
		.options = WDIOF_SETTIMEOUT,
		.firmware_version = 0,
	};

	wdev = file->private_data;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user((struct watchdog_info __user *)arg, &ident,
				sizeof(ident));
	case WDIOC_GETSTATUS:
		return put_user(0, (int __user *)arg);
	case WDIOC_GETBOOTSTATUS:
		if (cpu_is_omap16xx())
			return put_user(__raw_readw(ARM_SYSST),
					(int __user *)arg);
		if (cpu_is_omap24xx())
			return put_user(omap_prcm_get_reset_sources(),
					(int __user *)arg);
	case WDIOC_KEEPALIVE:
		spin_lock(&wdt_lock);
		omap_wdt_ping(wdev);
		spin_unlock(&wdt_lock);
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, (int __user *)arg))
			return -EFAULT;
		omap_wdt_adjust_timeout(new_margin);

		spin_lock(&wdt_lock);
		omap_wdt_disable(wdev);
		omap_wdt_set_timeout(wdev);
		omap_wdt_enable(wdev);

		omap_wdt_ping(wdev);
		spin_unlock(&wdt_lock);
		/* Fall */
	case WDIOC_GETTIMEOUT:
		return put_user(timer_margin, (int __user *)arg);
	default:
		return -ENOTTY;
	}
}

static const struct file_operations omap_wdt_fops = {
	.owner = THIS_MODULE,
	.write = omap_wdt_write,
	.unlocked_ioctl = omap_wdt_ioctl,
	.open = omap_wdt_open,
	.release = omap_wdt_release,
	.llseek = no_llseek,
};

static int __devinit omap_wdt_probe(struct platform_device *pdev)
{
	struct resource *res, *mem;
	struct omap_wdt_dev *wdev;
	int ret;

	/* reserve static register mappings */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		ret = -ENOENT;
		goto err_get_resource;
	}

	if (omap_wdt_dev) {
		ret = -EBUSY;
		goto err_busy;
	}

	mem = request_mem_region(res->start, resource_size(res), pdev->name);
	if (!mem) {
		ret = -EBUSY;
		goto err_busy;
	}

	wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
	if (!wdev) {
		ret = -ENOMEM;
		goto err_kzalloc;
	}

	wdev->omap_wdt_users = 0;
	wdev->mem = mem;
	wdev->dev = &pdev->dev;

	wdev->base = ioremap(res->start, resource_size(res));
	if (!wdev->base) {
		ret = -ENOMEM;
		goto err_ioremap;
	}

	platform_set_drvdata(pdev, wdev);

	pm_runtime_enable(wdev->dev);
	pm_runtime_get_sync(wdev->dev);

	omap_wdt_disable(wdev);
	omap_wdt_adjust_timeout(timer_margin);

	wdev->omap_wdt_miscdev.parent = &pdev->dev;
	wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
	wdev->omap_wdt_miscdev.name = "watchdog";
	wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;

	ret = misc_register(&(wdev->omap_wdt_miscdev));
	if (ret)
		goto err_misc;

	pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
		__raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
		timer_margin);

	pm_runtime_put_sync(wdev->dev);

	omap_wdt_dev = pdev;

	return 0;

err_misc:
	platform_set_drvdata(pdev, NULL);
	iounmap(wdev->base);

err_ioremap:
	wdev->base = NULL;
	kfree(wdev);

err_kzalloc:
	release_mem_region(res->start, resource_size(res));

err_busy:
err_get_resource:

	return ret;
}

static void omap_wdt_shutdown(struct platform_device *pdev)
{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users) {
		omap_wdt_disable(wdev);
		pm_runtime_put_sync(wdev->dev);
	}
}

static int __devexit omap_wdt_remove(struct platform_device *pdev)
{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res)
		return -ENOENT;

	misc_deregister(&(wdev->omap_wdt_miscdev));
	release_mem_region(res->start, resource_size(res));
	platform_set_drvdata(pdev, NULL);

	iounmap(wdev->base);

	kfree(wdev);
	omap_wdt_dev = NULL;

	return 0;
}

#ifdef	CONFIG_PM

/* REVISIT ... not clear this is the best way to handle system suspend; and
 * it's very inappropriate for selective device suspend (e.g. suspending this
 * through sysfs rather than by stopping the watchdog daemon).  Also, this
 * may not play well enough with NOWAYOUT...
 */

static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users) {
		omap_wdt_disable(wdev);
		pm_runtime_put_sync(wdev->dev);
	}

	return 0;
}

static int omap_wdt_resume(struct platform_device *pdev)
{
	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

	if (wdev->omap_wdt_users) {
		pm_runtime_get_sync(wdev->dev);
		omap_wdt_enable(wdev);
		omap_wdt_ping(wdev);
	}

	return 0;
}

#else
#define	omap_wdt_suspend	NULL
#define	omap_wdt_resume		NULL
#endif

static struct platform_driver omap_wdt_driver = {
	.probe		= omap_wdt_probe,
	.remove		= __devexit_p(omap_wdt_remove),
	.shutdown	= omap_wdt_shutdown,
	.suspend	= omap_wdt_suspend,
	.resume		= omap_wdt_resume,
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "omap_wdt",
	},
};

static int __init omap_wdt_init(void)
{
	spin_lock_init(&wdt_lock);
	return platform_driver_register(&omap_wdt_driver);
}

static void __exit omap_wdt_exit(void)
{
	platform_driver_unregister(&omap_wdt_driver);
}

module_init(omap_wdt_init);
module_exit(omap_wdt_exit);

MODULE_AUTHOR("George G. Davis");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:omap_wdt");