u-boot-2009.08在mini2440上的移植（十）---增加I2C EEPROM功能
移植環(huán)境
1，主機環(huán)境：VMare下CentOS 5.5 ，1G內存。
2，集成開發(fā)環(huán)境：Elipse IDE
3，編譯編譯環(huán)境：arm-linux-gcc v4.4.3，arm-none-eabi-gcc v4.5.1。
4，開發(fā)板：mini2440，2M nor flash，128M nand flash。
5，u-boot版本：u-boot-2009.08
6，參考文章：
http://blogimg.chinaunix.net/blog/upfile2/100811115954.pdf
10.1，實現(xiàn)u-boot的I2C EEPROM功能
mini2440開發(fā)板上的AT24C08A芯片提供了8kbyte的非易失的EEPROM存儲空間，而且是通過I2C協(xié)議進行讀寫的，U-boot提供了對I2C和EEPROM的操作支持。
打開/include/configs/mini2440.h，定位到206行附近，加入宏定義：
/*
* SD Card support
* */
#if 1
#define CONFIG_CMD_MMC
#define CONFIG_MMC1
#define CONFIG_MMC_S3C1/* Enabling the MMC driver */
#define CFG_MMC_BASE0xff000000
#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，重新編譯測試
待編譯完成后，nor檔下載nand檔啟動，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是注釋掉的，如果想將環(huán)境變量保存的位置設置在EEPROM中，需要將nandflash的CONFIG_ENV_IS_IN_NAND的相關幾行代碼注釋掉，將上面注釋掉的幾行代碼恢復即可。這里先不作修改了。
10.3 本次u-boot移植遺留問題
【1】由于mini2440出廠配置的LCD的型號是TD035STED4，是240X320分辨率的，是豎屏，但是想進行橫向輸出時遇到了困難，究竟怎么實現(xiàn)，還有待研究。
【2】開機時顯示的logo信息，旁邊空白的部分沒有文字顯示，如何實現(xiàn)開機是logo圖片周邊有文字環(huán)繞，還有待研究。
【3】開機時的詳細，可以通過環(huán)境變量stdout設置成vga是LCD輸出，serial是串口控制臺輸出?？匆雰烧咄瑫r輸出時遇到了困難。
【4】開機前LCD動畫顯示后在輸出信息還沒有實現(xiàn)。
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