測試Linux 核心中的I2c-dev.c

原文：http://hi.baidu.com/jjhopeforever/item/4e5e75c6156aa42ea1b50a67

       #include <stdio.h>

         #include <linux/types.h>

         #include <stdlib.h>

         #include <fcntl.h>

         #include <unistd.h>

         #include <sys/types.h>

         #include <sys/ioctl.h>

         #include <errno.h>

         #define I2C_RETRIES 0x0701

         #define I2C_TIMEOUT 0x0702

         #define I2C_RDWR 0x0707

struct i2c_msg

         {

                 unsigned short addr;

                 unsigned short flags;

         #define I2C_M_TEN 0x0010

         #define I2C_M_RD 0x0001

                 unsigned short len;

                 unsigned char *buf;

         };

struct i2c_rdwr_ioctl_data

         {

                 struct i2c_msg *msgs;

                 int nmsgs;

         };

         int main()

         {

                 int fd,ret;

                 struct i2c_rdwr_ioctl_data e2prom_data;

                 fd=open("/dev/i2c-0",O_RDWR);

                 if(fd<0)

                 {

                         perror("open error");

                 }

                 e2prom_data.nmsgs=2;

                 e2prom_data.msgs=(struct i2c_msg*)malloc(e2prom_data.nmsgs*sizeof(struct i2c_msg));

                 if(!e2prom_data.msgs)

                 {

                         perror("malloc error");

                         exit(1);

                 }

                 ioctl(fd,I2C_TIMEOUT,100);

                  ioctl(fd,I2C_M_TEN,0);

                 ioctl(fd,I2C_RETRIES,2);

                 e2prom_data.nmsgs=1;

                 (e2prom_data.msgs[0]).len=2; //1個 e2prom 寫入目标的位址和1個資料

                 (e2prom_data.msgs[0]).addr=0x5c;//e2prom 裝置位址

                 (e2prom_data.msgs[0]).flags=0; //write

                 (e2prom_data.msgs[0]).buf=(unsigned char*)malloc(2);

                 (e2prom_data.msgs[0]).buf[0]=0x01;// e2prom 寫入目标的位址

                 (e2prom_data.msgs[0]).buf[1]=0x74;//the data to write

         ret=ioctl(fd,I2C_RDWR,(unsigned long)&e2prom_data);

                 if(ret<0)

                 {

                         perror("ioctl error1");

                 }

                 sleep(1);

                 e2prom_data.nmsgs=2;

                 (e2prom_data.msgs[0]).len=1; //e2prom 目标資料的位址

                 (e2prom_data.msgs[0]).addr=0x5c; // e2prom 裝置位址

                 (e2prom_data.msgs[0]).flags=0;//write

                 (e2prom_data.msgs[0]).buf[0]=0x01;//e2prom資料位址

                 (e2prom_data.msgs[1]).len=1;//讀出的資料

                 (e2prom_data.msgs[1]).addr=0x5c;// e2prom 裝置位址

                 (e2prom_data.msgs[1]).flags=I2C_M_RD;//read

                 (e2prom_data.msgs[1]).buf=(unsigned char*)malloc(1);//存放傳回值的位址。

                 (e2prom_data.msgs[1]).buf[0]=0;//初始化讀緩沖

         ret=ioctl(fd,I2C_RDWR,(unsigned long)&e2prom_data);

                 if(ret<0)

                 {

                         perror("ioctl error2");

                 }

                 printf("buff[0]=%x\n",(e2prom_data.msgs[1]).buf[0]);

                 close(fd);

                 return 0;

         }