watchdog.c

ARM开发实例emed linuxexamples.tar.gz

/*
 * 实验名称：看门狗实验
 * 实验说明：S3C2410内部具有一个看门狗定时器，可以设置为看门狗功能，设定在一定时
             间内，如果没有将看门狗计数寄存器复位，将引发系统复位，本实验设定复
             位时间为2秒，如果在两秒内没有复位将导致系统复位。
 * 最后修改：2004-09-01
 */
#include <stdio.h>
#include <asm-arm/arch-s3c2410/S3C2410.h>
#include <sys/io.h>
#include <unistd.h>

#include "../include/directio.h"

#define _DEBUG_ printf

#define PCLK (50*1024*1024)

/*
 * watchdog application code
 * compile :
 *          $/usr/local/arm/2.95.3/bin/arm-linux-gcc -o watchdog watchdog.c
 *          $cp watchdog /tftpboot/examples
 * run in target:
 *          #mount 192.168.1.180:/tftpboot/ /mnt/nfs
 *          #cd /mnt/nfs/examples
 *          #insmod eintdrv.o
 *          #mknod eint c 98 0
 *          #./interrupt
 */
/*
 * 主函数
 */
int main(int argc, char **argv)
{
    /*
     *	t_watchdog = 1 / (PCLK / (Prescaler value + 1 ) / Division_factor)
     */
    _DEBUG_("WatchDog TimerTest!\n");
    _DEBUG_("t_watchdog = 1 / (PCLK / (Prescaler value + 1) / Division_factor)\n");

    /*
     * port_open 
     */
    if(port_init() != 0)
    {
        _DEBUG_("port open error\n");
	_DEBUG_("Please follow me:\n");
	_DEBUG_("    #insmod directio\n");
	_DEBUG_("    #mknod /dev/directio c 199 0\n");
	_DEBUG_("    #./watchdog\n");
        return -1;
    }

    /*
     * 设置看门狗控制寄存器rWTCON:
     *   PCLK = PCLK
     *   Prescaler = (PCLK/1000000-1)
     *   Clock division = 128
     */
    port_outl(rWTCON, ((PCLK/1000000-1)<<8) | (3<<3) | (1)); //Prescaler=0x31(49),Clock division 128,Interrupt disable,Watch-dog timer enable
    _DEBUG_("    PCLK = %dMHz\n", PCLK/1024/1024);
    _DEBUG_("    Prescaler value = %d\n", (PCLK/1000000-1));
    _DEBUG_("    Clock division = %d\n", 128);
    _DEBUG_("t_watchdog = %f\n", 1.0 / (PCLK / (((PCLK/1000000-1)) + 1) / (128)));

    /*
     * 设置看门狗计数寄存器rWTCNT
     *   wWTCNT = 16896
     */
    port_outl(rWTCNT, 8448 * 2); // 16896 (0x4200)
    
    _DEBUG_("Please feed the dog every %f sec, if not System will restart.\n", (8448 * 2) * 1.0 / (PCLK / (((PCLK/1000000-1)) + 1) / (128)));

    /*
     * 打开看门狗
     */
    port_outl(rWTCON, port_inl(rWTCON) | (1 << 5));
    while(1)
    {
        /*
         * 每秒钟喂狗一次，如果不喂狗，看门狗打开两秒钟后将复位
         */
        _DEBUG_("Feed the dog\n");
        port_outl(rWTCNT, 8448 * 2); // 16896 (0x4200)
        sleep(2);
    }

    /* uninit the port */
    port_uninit();
}