test.c

linux 简单字符设备驱动......

#include<sys/types.h>
#include<unistd.h>
#include<fcntl.h>
#include<linux/rtc.h>
#include<linux/ioctl.h>
#include<stdio.h>
#include<stdlib.h>

#define COMMAND1 1
#define COMMAND2 2

main()
{
int fd;
int i;
char data[256];

int retval;
fd=open("/dev/fgj",O_RDWR);
if(fd==-1)
{
     perror("error open\n");
     exit(-1);
}
printf("open /dev/smbus successfully\n");
retval=ioctl(fd,COMMAND1,0);
if(retval==-1)
{
    perror("ioctl error\n");
    exit(-1);
}
printf("send command1 successfully\n");

retval=write(fd,"fgj",3);
if(retval==-1)
{
    perror("write error\n");
    exit(-1);
}
retval=lseek(fd,0,0);
if(retval==-1)
{
    perror("lseek error\n");
    exit(-1);
}
retval=read(fd,data,3);

if(retval==-1)
{
    perror("read error\n");
    exit(-1);
}
   printf("read successfully:%s\n",data);
close(fd);
}