/* ***************************************************************************

* File name: eeprom_io.c

* Function: eeprom读写操作

* Description: 利用系统提供的I2C总线驱动实现eeprom设备的读写方法,

* 对外开放4个函数接口, 分别为:

* 单字节写入函数: int eeprom_byte_write(u8 pos, u8 data)

* 单字节读取函数: u8 eeprom_byte_read(u8 pos)

* 多字节写入函数: int eeprom_page_write(u8 pos, u8 *data, int size)

* 多字节读取函数: int eeprom_page_read(u8 pos, u8 *data, int size)

* Author & Date: Joshua Chan, 2011/12/18

* **************************************************************************/

#include

#include

#include

#include

#include

#include

#include "eeprom_io.h"

/* 对设备进行初始化设置, 设置超时时间及重发次数, 参数为设备文件描述符 */

static int eeprom_init(int fd)

{

ioctl(fd, I2C_TIMEOUT, 4);

ioctl(fd, I2C_RETRIES, 2);

return 0;

}

/* 初始化一个ioctl_st结构, 并预分配空间 */

static ioctl_st *ioctl_st_init(void)

{

ioctl_st *iocs;

iocs = malloc(sizeof(ioctl_st));

if (!(iocs)) {

perror("malloc iocs:");

return NULL;

}

iocs->msgs = malloc(I2C_MSG_SIZE * MAX_MSG_NR);

if (!(iocs->msgs)) {

perror("malloc iocs->msgs");

return NULL;

}

iocs->msgs[0].buf = malloc(EEPROM_PAGE_SIZE + 1);

if (!(iocs->msgs[0].buf)) {

perror("malloc iocs->msgs[0].buf");

return NULL;

}

iocs->msgs[1].buf = malloc(EEPROM_PAGE_SIZE + 1);

if (!(iocs->msgs[1].buf)) {

perror("malloc iocs->msgs[1].buf");

return NULL;

}

return iocs;

}

/* 销毁ioctl_st结构, 释放空间 */

static void ioctl_st_release(ioctl_st *iocs)

{

free(iocs->msgs[0].buf);

free(iocs->msgs[1].buf);

free(iocs->msgs);

free(iocs);

}

/* 根据eeprom_st结构生成page_read时序所需的ioctl_st结构 */

static void page_read_st_gen(ioctl_st *iocs, eeprom_st *eeps)

{

int size = eeps->len;

iocs->nmsgs = 2; //page_read需2次start信号

/* 第1次信号 */

iocs->msgs[0].addr = eeps->slave_addr; //填入slave_addr

iocs->msgs[0].flags = I2C_M_WR; //write标志

iocs->msgs[0].len = 1; //信号长度1字节

iocs->msgs[0].buf[0] = eeps->byte_addr; //填入byte_addr

/* 第2次信号 */

iocs->msgs[1].addr = eeps->slave_addr; //填入slave_addr

iocs->msgs[1].flags = I2C_M_RD; //read标志

iocs->msgs[1].len = size; //信号长度: 待读数据长度

memset(iocs->msgs[1].buf, 0, size); //先清零, 待读数据将自动存放于此

}

/* 用ioctl方法从eeprom中读取数据 */

static int page_read(int fd, ioctl_st *iocs, eeprom_st *eeps)

{

int ret;

int size = eeps->len;

page_read_st_gen(iocs, eeps);

ret = ioctl(fd, I2C_RDWR, (u32)iocs);

if (ret == -1) {

perror("ioctl");

return ret;

}

/* 将读取的数据从ioctl结构中复制到用户buf */

memcpy(eeps->buf, iocs->msgs[1].buf, size);

// printf("read byte ioctl ret = %d\n", ret);

return ret;

}

/* 从eeprom的pos位置开始读取size长度数据

@pos: eeprom的byte_address, 取值范围为0 ~ 255

@data: 接收数据的缓冲区

@size: 待读取的数据长度, 取值范围为1 ~ 16 */

int eeprom_page_read(u8 pos, u8 *data, int size)

{

int fd;

u8 *buf = data;

eeprom_st eeps;

ioctl_st *iocs = ioctl_st_init();

fd = open(DEV_PATH, O_RDONLY);

if (fd < 0) {

perror("open eeprom");

return 0;

}

/* 判断要读取数据的长度size有效性 */

if (size > 16)

size = 16;

else if (size < 1)

return 0;

if (size > (EEPROM_BLOCK_SIZE - pos))

size = EEPROM_BLOCK_SIZE - pos;

eeprom_init(fd);

eeps.slave_addr = eeprom_addr0;

eeps.byte_addr = pos;

eeps.len = size;

eeps.buf = buf;

page_read(fd, iocs, &eeps);

ioctl_st_release(iocs);

close(fd);

return size;

}

/* 根据eeprom_st结构生成page_write时序所需的ioctl_st结构 */

static void page_write_st_gen(ioctl_st *iocs, eeprom_st *eeps)

{

int size = eeps->len;

iocs->nmsgs = 1; //page_write只需1次start信号

iocs->msgs[0].addr = eeps->slave_addr; //填入slave_addr

iocs->msgs[0].flags = I2C_M_WR; //write标志

iocs->msgs[0].len = size + 1; //信号长度: 待写入数据长度 + byte_addr长度

iocs->msgs[0].buf[0] = eeps->byte_addr; //第1字节为byte_addr

memcpy((iocs->msgs[0].buf + 1), eeps->buf, size); //copy待写数据

}

/* 用ioctl方法向eeprom中写入数据 */

static int page_write(int fd, ioctl_st *iocs, eeprom_st *eeps)

{

int ret;

page_write_st_gen(iocs, eeps);

ret = ioctl(fd, I2C_RDWR, (u32)iocs);

if (ret == -1) {

perror("ioctl");

return ret;

}

printf("write byte ioctl ret = %d\n", ret);

return ret;

}

/* 自eeprom的pos位置开始写入数据

@pos: eeprom的byte_address, 取值范围为0 ~ 255

@data: 待写入的数据

@size: 待写入数据的长度, 取值范围为1 ~ 16 */

int eeprom_page_write(u8 pos, u8 *data, int size)

{

int fd;

u8 *buf = data;

eeprom_st eeps;

ioctl_st *iocs = ioctl_st_init();

fd = open(DEV_PATH, O_WRONLY);

if (fd < 0) {

perror("open eeprom");

return 0;

}

/* 判断要读取数据的长度size有效性 */

if (size > 16)

size = 16;

else if (size < 1)

return 0;

if (size > (EEPROM_BLOCK_SIZE - pos))

size = EEPROM_BLOCK_SIZE - pos;

eeprom_init(fd);

eeps.slave_addr = eeprom_addr0;

eeps.byte_addr = pos;

eeps.len = size;

eeps.buf = buf;

page_write(fd, iocs, &eeps);

ioctl_st_release(iocs);

close(fd);

return size;

}

/* 从eeprom的pos位置处读取1个字节

@pos: eeprom的byte_address, 取值范围为0 ~ 255

返回值为读取的字节数据 */

u8 eeprom_byte_read(u8 pos)

{

u8 buf;

eeprom_page_read(pos, &buf, 1);

return buf;

}

/* 将1个字节数据写入eeprom的pos位置

@pos: eeprom的byte_address, 取值范围为0 ~ 255

@data: 待写入的字节数据 */

int eeprom_byte_write(u8 pos, u8 data)

{

int ret;

u8 buf = data;

ret = eeprom_page_write(pos, &buf, 1);

return ret;

}