linux下通过i2c总线读写EEPROM

by 韩大卫@吉林师范大学

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转载请务必表明出处。

我的上篇文章《Linux下使用I2C总线读写 EEPROM（读写i2c从设备通用程序）》给出了通过IIC总线，如何读写EEPROM相应位置的内容。

但是有一些功能没有实现：

比如：  只能单独操作一个寄存器地址，不能一次性写入大量内容；
    只能读一个寄存器的数值，不能可选择性地一次读出大量内容；

这是由于为了做到通用化，我们的i2c没有一次性大量读写的功能。 在本程序中针对EEPROM做了一些改进,详细说明可以在help_info() 中找到。

FOR EXAMPLE:

    eep -r  0x08                        Display the contents of EEPROM from 0x00 to 0x08

    eep -ro 0x08                        Display the contents of EEPROM from 0x08

    eep -r  0x02 0x80                    Display the contents of EEPROM from address 0x20 to x080

    eep -s  0x04 "hello world!"                Write "hello world!" to EEPROM from 0x04

    eep -d /dev/i2c-1 -s  0x04 "hello world!"        Write "hello world!" to EEPROM from 0x04 with path"/dev/i2c-1"

*************************************************************

以下是具体代码：

main.c

********************** *******************************

#include "i2c.h"

#define TIMEOUT        4
#define RETRY        2
#define READ_ONLY    1

static int fd ;
static int addr = 0x57;  // EEPROM addr
static int offset;
static int offset_end;

inline int read_data(u16 addr, u8 offset, u8 *val){
    int ret;
   
    ret = i2c_read_data(addr,offset,val);
    if(ret < 0){
        printf("%s error!\n",__FUNCTION__);
        exit(-1);
    }
    return 0;
}

inline int write_data(u16 addr, u8 offset, u8 val){
    int ret;
   
    ret = i2c_write_data(addr,offset,val);
    if(ret < 0){
        printf("%s:error = %s\n",__FUNCTION__,strerror(errno));
        exit(-1);
    }
    usleep(10000);    // 重要！
    return 0;
}

int eep_write(u16 addr,u8 offset,char* argv){
    //u8 data = (u8)strtoul(argv,0,16);

    int i,j,len    = 0;
    char* data    = argv;
   
    while( *data++ ){
        len++;
    }
    data = argv;

    printf("len = %d\n",len);

    for( i = offset ,j = 0;i < offset + len ;i++,j++ ){
        write_data(addr,i,data[j]);
    }
    printf("write success,data = %s\n",argv);
    return 0;
}

int eep_read(u16 addr,u8 offset_start,u8 offset_end,int flags){
   
    int i;
    u8 buf[256] = {0};

    if( flags ){
        read_data(addr,offset_end,&buf[0]);
        printf("read success,data[%d] = %c\n",offset,buf[0]);
    }else{
        printf("read success,data = ");
        for(i = offset_start ; i <= offset_end ; i++){       
            read_data(addr,i,&buf[i]);       
            printf("%c",buf[i]);   
        }
        printf("\n");
    }   
   
    return 0;
}

void error_info(void){
    printf("cmd error! ");
    printf("Please input --help or -h  for help information\n");
    exit(-1);
}   

void help_info(void){
        printf("\nUsage: eep OPTIONS OFFSET [OFFSET_END] [DATA]\n");
        printf("\nDisplay the contents of EEPROM ,or write DATA to EEPROM\n");
        printf("\nOptions:\n");
        printf("\n\t-r OFFST \t\t\t\tDisplay the contents of EEPROM from 0x00 to OFFSET\n");
        printf("\n\t-r OFFSET OFFSET_END\t\t\tDisplay the contents of EEPROM from OFFSET to OFFSET_END\n");
        printf("\n\t-s OFFSET DATA\t\t\t\twrite DATA to EEPROM form OFFSET\n");
    printf("\n\t-h or --help\t\t\t\tshow help information\n");
    printf("\nOFFSET\tFORMAT: 0xXX  0xXX can change from 00 to ff\n");
    printf("\nFOR EXAMPLE:\n");
    printf("\n\teep -r  0x08\t\t\t\tDisplay the contents of EEPROM from 0x00 to 0x08\n");
    printf("\n\teep -ro 0x08\t\t\t\tDisplay the contents of EEPROM from 0x08\n");
    printf("\n\teep -r  0x02 0x80\t\t\tDisplay the contents of EEPROM from address 0x20 to x080\n");
    printf("\n\teep -s  0x04 \"hello world!\"\t\tWrite \"hello world!\" to EEPROM from 0x04\n\n");
}

int i2c_path(char * argv){

    fd = i2c_open(argv,TIMEOUT,RETRY);
    if( fd < 0 ){   
        printf("i2c_open error!\n");
        exit(-1);
    }   
    return 0;
}

int i2c_offs(char *argv){
    return (u8)strtoul(argv,0,16);
}

int main(int argc,char* argv[]){

    int flags;
   
    switch(argc){
    case 2 :{
                if(!strcmp(argv[1],"-h") || !strcmp(argv[1],"--help")){
                        help_info();
                }else
            error_info();
        }break;
        case 3 :{
        if(!strcmp(argv[1],"-r" )|| !strcmp(argv[1],"-ro" )){
            flags    = (!strcmp(argv[1],"-ro")) ? READ_ONLY : 0 ;
                    i2c_path("/dev/i2c-0");
            offset    = i2c_offs(argv[2]);   
            eep_read(addr,0,offset,flags);
        }else
            error_info();   
        }break;
        case 4 :{
        if(!strcmp(argv[1],"-r")){
                    i2c_path("/dev/i2c-0");
            offset        = i2c_offs(argv[2]);   
            offset_end    = i2c_offs(argv[3]);   
            eep_read(addr,offset,offset_end,0);
        }else if(!strcmp(argv[1],"-s")){
            i2c_path("/dev/i2c-0");
            offset        = i2c_offs(argv[2]);
            eep_write(addr,offset,argv[3]);   
        }else
            error_info();   
        }break;
        case 5 :{
                if(!strcmp(argv[1],"-d")){
                        i2c_path(argv[2]);
                    if(!strcmp(argv[3],"-r") || !strcmp(argv[3],"-ro")){
                            i2c_offs(argv[4]);
                flags   = (!strcmp(argv[3],"-ro")) ? READ_ONLY : 0 ;
                            offset  = i2c_offs(argv[4]);   
                            eep_read(addr,0,offset,flags);
            }else
                error_info();
                }else
            error_info();
        }break;
        case 6 :{
              if(!strcmp(argv[1],"-d")){
                        i2c_path(argv[2]);
                        if(!strcmp(argv[3],"-r")){
                                offset        = i2c_offs(argv[4]);
                offset_end    = i2c_offs(argv[5]);
                eep_read(addr,offset,offset_end,0);
                        }else if(!strcmp(argv[3],"-s")){
                offset        = i2c_offs(argv[4]);
                eep_write(addr,offset,argv[5]);
            }else
                error_info();
                }else
            error_info();   
        }break;
        default:
            error_info();   
        }

    return 0;
}

*************************** ********************************

i2c.c

*********************************************************

#include "i2c.h"

static int fd;


int
i2c_read_data(u16 addr, u8 offset, u8 *val)
{
    int i,ret = 0;

    struct i2c_rdwr_ioctl_data *data;

    if ((data = (struct i2c_rdwr_ioctl_data *)malloc(sizeof(struct i2c_rdwr_ioctl_data))) == NULL)
    return -1;

    data->nmsgs = 2;
    if ((data->msgs = (struct i2c_msg *)malloc(data->nmsgs * sizeof(struct i2c_msg))) == NULL) {
        ret = -1;
        goto errexit3;
    }
    if ((data->msgs[0].buf = (unsigned char *)malloc( EEPROM_PAGE_SIZE + 1 )) == NULL) {
        ret = -1;
        goto errexit2;
    }
    if ((data->msgs[1].buf = (unsigned char *)malloc( EEPROM_PAGE_SIZE + 1 )) == NULL) {
        ret = -1;
        goto errexit1;
    }

    data->msgs[0].addr    = addr;
    data->msgs[0].flags    = I2C_M_WR;
    data->msgs[0].len    = 1;
    data->msgs[0].buf[0]    = offset;

    data->msgs[1].addr    = addr;
    data->msgs[1].flags    = I2C_M_RD;
    data->msgs[1].len    = 1;   
    data->msgs[1].buf[0]    = 0;

    if ((ret = __i2c_send(fd, data)) < 0)   
        goto errexit0;


    for(i = 0 ;i < data->msgs[1].len; i++)
        val[i] = data->msgs[1].buf[i];

errexit0:
    free(data->msgs[1].buf);
errexit1:
    free(data->msgs[0].buf);
errexit2:
    free(data->msgs);
errexit3:
    free(data);

    return ret;
}

int
i2c_write_data(u16 addr, u8 offset, u8 val)
{
    int ret = 0;

    struct i2c_rdwr_ioctl_data *data;

    if ((data = (struct i2c_rdwr_ioctl_data *)malloc(sizeof(struct i2c_rdwr_ioctl_data))) == NULL)
        return -1;

    data->nmsgs = 1;
    if ((data->msgs = (struct i2c_msg *)malloc(data->nmsgs * sizeof(struct i2c_msg))) == NULL) {
        ret = -1;
        goto errexit2;
    }
    if ((data->msgs[0].buf = (unsigned char *)malloc( 2 * (EEPROM_PAGE_SIZE + 1))) == NULL) {
        ret = -1;
        goto errexit1;
    }


    data->msgs[0].addr    = addr;
    data->msgs[0].flags    = 0;
    data->msgs[0].len    = 2;
    data->msgs[0].buf[0]    = offset;
    data->msgs[0].buf[1]    = val;

    if ((ret = __i2c_send(fd, data)) < 0){
        ret = -1;
        goto errexit0;
    }

errexit0:
    free(data->msgs[0].buf);
errexit1:
    free(data->msgs);
errexit2:
    free(data);

    return ret;
}

int
i2c_open(unsigned char* dev, unsigned int timeout, unsigned int retry)
{
    if ((fd = open(dev, O_RDWR)) < 0)
        return fd;
    __i2c_set(fd, timeout, retry);

    return fd;
}

static int
__i2c_send(int fd, struct i2c_rdwr_ioctl_data *data)
{
    if (fd < 0)
        return -1;

    if (data == NULL)
        return -1;

    if (data->msgs == NULL || data->nmsgs == 0)
        return -1;
   
    return ioctl(fd, I2C_RDWR, (unsigned long)data) ;
}

static int
__i2c_set(int fd, unsigned int timeout, unsigned int retry)
{
    if (fd == 0 )
        return -1;

    ioctl(fd, I2C_TIMEOUT, timeout ? timeout : I2C_DEFAULT_TIMEOUT);
    ioctl(fd, I2C_RETRIES, retry ? retry : I2C_DEFAULT_RETRY);
   
    return 0;
}

void
i2c_close(int fd)
{
    if (fd < 0)
        return;

    close(fd);
}


unsigned bcd2bin(unsigned char val)
{      
        return (val & 0x0f) + (val >> 4) * 10; 
}

unsigned char bin2bcd(unsigned val)
{      
        return ((val / 10) << 4) + val % 10;
}   

******************************************************

i2c.h:

*********************************************************

 #ifndef _EEPROM_IO_H
#define _EEPROM_TO_H

#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <linux/rtc.h>
#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>
#include <string.h>

#define I2C_DEFAULT_TIMEOUT        1
#define I2C_DEFAULT_RETRY        2

#define I2C_M_WR        0                //定义写标志
#define MAX_MSG_NR        2                //根据AT24C02手册, 最大消息数为2
#define EEPROM_BLOCK_SIZE    256                //每个block容量256 bytes
#define EEPROM_PAGE_SIZE    8                  //用页写，AT24C02页大小为8字节
#define I2C_MSG_SIZE         (sizeof(struct i2c_msg))

typedef unsigned char           u8;
typedef unsigned short          u16;
typedef unsigned int            u32;
typedef unsigned long long      u64;
typedef signed char             s8;
typedef short                   s16;            
typedef int                     s32;
typedef long long               s64;

unsigned bcd2bin(unsigned char val);

unsigned bcd2bin(unsigned char val);

static int
__i2c_send(int fd, struct i2c_rdwr_ioctl_data *data);

static int
__i2c_set(int fd, unsigned int timeout, unsigned int retry);

int
i2c_read_data(u16 addr, u8 offset, u8 *val);

int
i2c_write_data(u16 addr, u8 offset, u8 val);

int
i2c_open(unsigned char* dev, unsigned int timeout, unsigned int retry);

#endif
****************************************************************