test2.c

来自「《linux驱动程序设计从入门到精通》一书中所有的程序代码含驱动和相应的应用程序」· C语言 代码 · 共 57 行

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2007, 2010 fengGuojin([e-mail])
 */
#include<sys/types.h>
#include<unistd.h>
#include<fcntl.h>
#include<linux/rtc.h>
#include<linux/ioctl.h>
#include<stdio.h>
#include<stdlib.h>

main()
{
  int fd;
  int i=0;;
  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");
  
  while(i<1000)
  {
	retval=write(fd,"222",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("read2 successfully:%s\n",data);
	i++;
   }
  close(fd);
}