linux I2C读写应用程序

本文代码参考ZFZF294990051 童鞋的代码，非常感谢ZFZF294990051童鞋。

参考地址：http://blog.csdn.net/zfzf294990051/article/details/17322621

#include <stdio.h>#include <linux/i2c.h>#include <linux/i2c-dev.h>#include <fcntl.h>#include <stdlib.h>#include <unistd.h>#include <sys/ioctl.h>#include <string.h>#include "ql_commfunc.h"#define I2C_FILE_NAME "/dev/i2c-0"static int get_i2c_register(int file,                            unsigned short addr,                            unsigned char reg,                            unsigned char *val,int len) {    //unsigned char inbuf, outbuf;    unsigned char outbuf;    struct i2c_rdwr_ioctl_data packets;    struct i2c_msg messages[2];    /*     * In order to read a register, we first do a "dummy write" by writing     * 0 bytes to the register we want to read from.  This is similar to     * the packet in set_i2c_register, except it's 1 byte rather than 2.     */    outbuf = reg;    messages[0].addr  = addr;    messages[0].flags = 0;    messages[0].len   = sizeof(outbuf);    messages[0].buf   = &outbuf;    /* The data will get returned in this structure */    messages[1].addr  = addr;    messages[1].flags = I2C_M_RD/* | I2C_M_NOSTART*/;    messages[1].len   = len;    messages[1].buf   = val;    /* Send the request to the kernel and get the result back */    packets.msgs      = messages;    packets.nmsgs     = 2;    if(ioctl(file, I2C_RDWR, &packets) < 0) {        perror("Unable to send data");        return 1;    }    //*val = inbuf;    return 0;}static int set_i2c_register(int file,                            unsigned char addr,                            unsigned char reg,                            unsigned char *value,    int len) {    unsigned char *outbuf = (unsigned char *)malloc(sizeof(unsigned char)*(len+1));if(outbuf==NULL){perror("MALLOC");return -1;}    struct i2c_rdwr_ioctl_data packets;    struct i2c_msg messages[1];    messages[0].addr  = addr;    messages[0].flags = 0;    messages[0].len   = len+1;    messages[0].buf   = outbuf;    /* The first byte indicates which register we'll write */    outbuf[0] = reg;    /*      * The second byte indicates the value to write.  Note that for many     * devices, we can write multiple, sequential registers at once by     * simply making outbuf bigger.     *///    outbuf[1] = value;memcpy(outbuf+1, value, len);    /* Transfer the i2c packets to the kernel and verify it worked */    packets.msgs  = messages;    packets.nmsgs = 1;    if(ioctl(file, I2C_RDWR, &packets) < 0) {        perror("Unable to send data");        return 1;    }    return 0;}int ql_get_i2c_register(unsigned short slave_addr, unsigned char reg, unsigned char *outbuf, int buf_len ){int fd;// Open a connection to the I2C userspace control file.if ((fd = open(I2C_FILE_NAME, O_RDWR)) < 0) {PERROR("Unable to open i2c control file");return -1;        //exit(1);}if(get_i2c_register(fd, slave_addr, reg, outbuf, buf_len)){DEBUG("");return -2;}close(fd);return 0;}int ql_set_i2c_register(unsigned short slave_addr, unsigned char reg, unsigned char *inbuf, int buf_len ){int fd;        // Open a connection to the I2C userspace control file.        if ((fd = open(I2C_FILE_NAME, O_RDWR)) < 0) {                PERROR("Unable to open i2c control file");                return -1;                //exit(1);        }        if(set_i2c_register(fd, slave_addr, reg, inbuf, buf_len))        {                DEBUG("");                return -4;        }        close(fd);        return 0;}