1，主机环境：VMare下CentOS 5.5 ，1G内存。
2，集成开发环境：Elipse IDE
3，编译编译环境：arm-linux-gcc v4.4.3，arm-none-eabi-gcc v4.5.1。
4，开发板：mini2440，2M nor flash，128M nand flash。
5，u-boot版本：u-boot-2009.08
6，参考文章：
10.1，实现u-boot的I2C EEPROM功能
mini2440开发板上的AT24C08A芯片提供了8kbyte的非易失的EEPROM存储空间，而且是通过I2C协议进行读写的，U-boot提供了对I2C和EEPROM的操作支持。
打开/include/configs/mini2440.h，定位到206行附近，加入宏定义：
/*
* SD Card support
* */
#if 1
#define CONFIG_CMD_MMC
#define CONFIG_MMC 1
#define CONFIG_MMC_S3C 1 /* Enabling the MMC driver */
#define CFG_MMC_BASE 0xff000000
#endif
/**
* I2C and EEPROM support
*/
#if 1
#define CONFIG_CMD_EEPROM
#define CONFIG_CMD_I2C
#define CONFIG_DRIVER_S3C24X0_I2C 1 /* we use the buildin I2C controller */
#define CONFIG_HARD_I2C 1 /* I2C with hardware support */
#define CONFIG_SYS_I2C_SPEED 100000 /* I2C speed and slave address */
#define CONFIG_SYS_I2C_SLAVE 0x7F
#define CONFIG_SYS_I2C_EEPROM_ADDR 0x50 /* EEPROM at24c08 */
#define CONFIG_SYS_I2C_EEPROM_ADDR_LEN 1 /* Bytes of address */
/* mask of address bits that overflow into the "EEPROM chip address" */
#define CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW 0x07
#define CONFIG_SYS_EEPROM_PAGE_WRITE_BITS 4 /* The Catalyst CAT24WC08 has */
/* 16 byte page write mode using*/
/* last 4 bits of the address */
#define CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS 10 /* and takes up to 10 msec */
#define CONFIG_SYS_EEPROM_PAGE_WRITE_ENABLE
//#define CONFIG_ENV_IS_IN_EEPROM 1 /* use EEPROM for environment vars */
//#define CONFIG_ENV_OFFSET 0x000 /* environment starts at offset 0 */
//#define CONFIG_ENV_SIZE 0x400 /* 1KB */
#endif
10.2，重新编译测试
待编译完成后，nor档下载nand档启动，操作如下：
[u-boot@MINI2440]# help i2c
i2c - I2C sub-system
Usage:
i2c speed [speed] - show or set I2C bus speed
i2c md chip address[.0, .1, .2] [# of objects] - read from I2C device
i2c mm chip address[.0, .1, .2] - write to I2C device (auto-incrementing)
i2c mw chip address[.0, .1, .2] value [count] - write to I2C device (fill)
i2c nm chip address[.0, .1, .2] - write to I2C device (constant address)
i2c crc32 chip address[.0, .1, .2] count - compute CRC32 checksum
i2c probe - show devices on the I2C bus
i2c reset - re-init the I2C Controller
i2c loop chip address[.0, .1, .2] [# of objects] - looping read of device
[u-boot@MINI2440]# i2c speed
Current bus speed=100000
[u-boot@MINI2440]# i2c probe
Valid chip addresses: 50 51 52 53
[u-boot@MINI2440]# i2c
在上面的mini2440.h文件中， CONFIG_ENV_IS_IN_EEPROM 是注释掉的，如果想将环境变量保存的位置设置在EEPROM中，需要将nand flash的CONFIG_ENV_IS_IN_NAND 的相关几行代码注释掉，将上面注释掉的几行代码恢复即可。这里先不作修改了。