嵌入式Linux之我行——u-boot-2009.08在2440上的移植详解（五）

Yaffs页结构说明

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   字节                   用途

==============================================

 0 - 511                存储数据(分为两个半部)

512 - 515               系统信息

   516                  数据状态字

   517                  块状态字

518 - 519               系统信息

520 - 522               后半部256字节的ECC

523 - 524               系统信息

525 - 527               前半部256字节的ECC

==============================================

#gedit include/configs/my2440.h 
//添加到文件末尾即可

#define CONFIG_MTD_NAND_YAFFS2   1
//定义一个管理对Yaffs2支持的宏

//开启Nand Flash默认分区，注意此处的分区要和你的内核中的分区保持一致

#define MTDIDS_DEFAULT 
"nand0=nandflash0"

#define MTDPARTS_DEFAULT "mtdparts=nandflash0:192k(bootloader)," \

                     "64k(params)," \

                     "2m(kernel)," \

                     "-(root)"

#gedit common/cmd_nand.c  
//在U_BOOT_CMD中添加

#gedit include/linux/mtd/mtd.h  
//在mtd_info结构体中添加

#if defined(CONFIG_MTD_NAND_YAFFS2)

    u_char rw_oob;

    u_char skipfirstblk;

#endif

#gedit drivers/mtd/nand/nand_util.c 
//在nand_write_skip_bad函数中添加

#gedit drivers/mtd/nand/nand_base.c 
//在nand_write函数中添加

static int nand_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen, const uint8_t *buf)

{

    struct nand_chip *chip = mtd->priv;

    int ret;

#if defined(CONFIG_MTD_NAND_YAFFS2)
//add yaffs2 file system support

int oldopsmode = 0;

if(mtd->rw_oob==1)   

    {

        int i = 0;

        int datapages = 0;

size_t oobsize = mtd->oobsize;

        size_t datasize = mtd->writesize;

uint8_t oobtemp[oobsize];

        datapages = len / (datasize);

for(i = 0; i < (datapages); i++)   

        {

            memcpy((void *)oobtemp, (void *)(buf + datasize * (i + 1)), oobsize);

            memmove((void *)(buf + datasize * (i + 1)), (void *)(buf + datasize * (i + 1) + oobsize), (datapages - (i + 1)) * (datasize) + (datapages - 1) * oobsize);

            memcpy((void *)(buf+(datapages) * (datasize + oobsize) - oobsize), (void *)(oobtemp), oobsize);

        }

    }

#endif

/* Do not allow reads past end of device */

    if ((to + len) > mtd->size)

        return -EINVAL;

    if (!len)

        return 0;

nand_get_device(chip, mtd, FL_WRITING);

chip->ops.len = len;

    chip->ops.datbuf = (uint8_t *)buf;

#if defined(CONFIG_MTD_NAND_YAFFS2)
//add yaffs2 file system support

if(mtd->rw_oob!=1)   

    {

        chip->ops.oobbuf = NULL;

    } 

    else    

    {

        chip->ops.oobbuf = (uint8_t *)(buf + len);

        chip->ops.ooblen = mtd->oobsize;

        oldopsmode = chip->ops.mode;

        chip->ops.mode = MTD_OOB_RAW;

    }

#else

    chip->ops.oobbuf = NULL;

#endif

ret = nand_do_write_ops(mtd, to, &chip->ops);

*retlen = chip->ops.retlen;

nand_release_device(mtd);

#if defined(CONFIG_MTD_NAND_YAFFS2)
//add yaffs2 file system support

chip->ops.mode = oldopsmode;

#endif

return ret;

}

tftp 0x30000000 root-2.6.30.4.bin
//用tftp将yaffs2文件系统下载到内存的0x30000000位置

nand erase 0x250000 0x3dac000 //擦除Nand的文件系统分区

nand write.yaffs2 0x30000000 0x250000 0x658170 //将内存中的yaffs2文件系统写入Nand的文件系统分区，注意这里的0x658170是yaffs2文件系统的实际大小(可以在tftp传送完后可以看到)，要写正确，否则会形成假坏块