I2C 通信 api

把之前的oled从rtos移植到linux时，抽了个IIC通信api粗来 ⊙▽⊙

Header: i2c-api.h

//
//  i2c-api.h
//  i2c-api
//
//  Created by MetalSeed on 15/4/11.
//  Copyright (c) 2015年 MetalSeed. All rights reserved.
//

#ifndef i2c_api_i2c_api_h
#define i2c_api_i2c_api_h


#include <linux/i2c-dev.h> // include I2C_FUNC_SMBUS_
#include <linux/i2c.h>

#define IIC_TYPE_UNKNOWN    0
#define IIC_TPPE_OLED       1
#define IIC_TYPE_8BIT_ADDR  2
#define IIC_TYPE_16BIT_ADDR 3

struct i2c_obj
{
    char *dev;  // device file i.e. /dev/i2c-N
    int addr;   // i2c address
    int fd;     // file descriptor
    int type;   // device type
};

/*
 * opens the i2c device at [dev_fqn] (i.e. /dev/i2c-N) whose address is
 * [addr] and set the i2c_object [e]
 */
int i2c_open(char *dev_fqn, int addr, int type, struct i2c_obj*);
/*
 * closees the i2c device [e]
 */
int i2c_close(struct i2c_obj *e);
/*
 * read and returns the i2c byte at memory address [mem_addr]
 * Note: i2c must have been selected by ioctl(fd,I2C_SLAVE,address)
 */
int i2c_read_byte(struct i2c_obj* e, __u16 mem_addr);
/*
 * read the current byte
 * Note: i2c must have been selected by ioctl(fd,I2C_SLAVE,address)
 */
int i2c_read_current_byte(struct i2c_obj *e);
/*
 * writes [data] at memory address [mem_addr]
 * Note: i2c must have been selected by ioctl(fd,I2C_SLAVE,address)
 */
int i2c_write_byte(struct i2c_obj *e, __u16 mem_addr, __u8 data);

#endif

Source: i2c-api.c

//
//  main.c
//  i2c-api
//
//  Created by MetalSeed on 15/4/11.
//  Copyright (c) 2015年 MetalSeed. All rights reserved.
//

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <linux/fs.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <assert.h>
#include <string.h>

#include "i2c-api.h"


//
//
// i2c smbus func
//
//

static inline __s32 i2c_smbus_access(int file, char read_write, __u8 command,
                                     int size, union i2c_smbus_data *data)
{