一、移植环境
- 主 ?机:VMWare--Fedora 9
- 开发板:Mini2440--64MB Nand,Kernel:2.6.30.4
- 编译器:arm-linux-gcc-4.3.2.tgz
- u-boot:u-boot-2009.08.tar.bz2
二、移植步骤
?????????? Yaffs页结构说明
==============================================
???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
==============================================
??? 好了,在了解Nand Flash组成和Yaffs/yaffs2文件系统结构后,我们再回到u-boot中。目前,在u-boot中已经有对Cramfs、Jffs2等文件系统的读写支持,但与带有数据校验等功能的OOB区的Yaffs/Yaffs2文件系统相比,他们是将所有文件数据简单的以线性表形式组织的。所以,我们只要在此基础上通过修改u-boot的Nand Flash读写命令,增加处理00B区域数据的功能,即可以实现对Yaffs/Yaffs2文件系统的读写支持。
#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)"
②、在原来对Nand操作的命令集列表中添加Yaffs2对Nand的写命令,如下:
?
接着,在该文件中对nand操作的do_nand函数中添加yaffs2对nand的操作,如下:
??? if (strncmp(cmd, "read", 4) == 0 || strncmp(cmd, "write", 5) == 0)
??? {
??????? int read;
??????? if (argc < 4)
??????????? goto usage;
??????? addr = (ulong)simple_strtoul(argv[2], NULL, 16);
??????? read = strncmp(cmd, "read", 4) == 0; /* 1 = read, 0 = write */
??????? printf("\nNAND %s: ", read ? "read" : "write");
??????? if (arg_off_size(argc - 3, argv + 3, nand, &off, &size) != 0)
??????????? return 1;
??????? s = strchr(cmd, '.');
??????? if (!s || !strcmp(s, ".jffs2") || !strcmp(s, ".e") || !strcmp(s, ".i"))
??????? {
??????????? if (read)
??????????????? ret = nand_read_skip_bad(nand, off, &size, (u_char *)addr);
??????????? else
??????????????? ret = nand_write_skip_bad(nand, off, &size, (u_char *)addr);
??????? }
//添加yaffs2相关操作,注意该处又关联到nand_write_skip_bad函数
#if defined(CONFIG_MTD_NAND_YAFFS2)
??????? else if (s != NULL && (!strcmp(s, ".yaffs2")))
??????? {
??????????? nand->rw_oob = 1;
??????????? nand->skipfirstblk = 1;
??????????? ret = nand_write_skip_bad(nand,off,&size,(u_char *)addr);
??????????? nand->skipfirstblk = 0;
??????????? nand->rw_oob = 0;
??????? }
#endif
??????? else if (!strcmp(s, ".oob"))
??????? {
??????????? /* out-of-band data */
??????????? mtd_oob_ops_t ops =
??????????? {
??????????????? .oobbuf = (u8 *)addr,
??????????????? .ooblen = size,
??????????????? .mode = MTD_OOB_RAW
??????????? };
??????????? if (read)
??????????????? ret = nand->read_oob(nand, off, &ops);
??????????? else
??????????????? ret = nand->write_oob(nand, off, &ops);
??????? }
??????? else
??????? {
??????????? printf("Unknown nand command suffix '%s'.\n", s);
??????????? return 1;
??????? }
??????? printf(" %zu bytes %s: %s\n", size, read ? "read" : "written", ret ? "ERROR" : "OK");
??????? return ret == 0 ? 0 : 1;
??? }
③、在include/linux/mtd/mtd.h头文件的mtd_info结构体中添加上面用到rw_oob和skipfirstblk数据成员,如下:
#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
④、在第二步关联的nand_write_skip_bad函数中添加对Nand OOB的相关操作,如下:
#gedit drivers/mtd/nand/nand_util.c? //在nand_write_skip_bad函数中添加
int nand_write_skip_bad(nand_info_t *nand, loff_t offset, size_t *length, u_char *buffer)
{
??? int rval;
??? size_t left_to_write = *length;
??? size_t len_incl_bad;
??? u_char *p_buffer = buffer;
#if defined(CONFIG_MTD_NAND_YAFFS2) //add yaffs2 file system support
??? if(nand->rw_oob==1)???
??? {
??????? size_t oobsize = nand->oobsize;
??????? size_t datasize = nand->writesize;
??????? int datapages = 0;
??????? if (((*length)%(nand->oobsize+nand->writesize)) != 0)
??????? {
???????? printf ("Attempt to write error length data!\n");
???????? return -EINVAL;
???? }
??????? datapages = *length/(datasize+oobsize);
??????? *length = datapages*datasize;
??????? left_to_write = *length;
??? }
#endif
??? /* Reject writes, which are not page aligned */
??? if ((offset & (nand->writesize - 1)) != 0 ||
???? (*length & (nand->writesize - 1)) != 0) {
??????? printf ("Attempt to write non page aligned data\n");
??????? return -EINVAL;
??? }
??? len_incl_bad = get_len_incl_bad (nand, offset, *length);
??? if ((offset + len_incl_bad) >= nand->size) {
??????? printf ("Attempt to write outside the flash area\n");
??????? return -EINVAL;
??? }
#if !defined(CONFIG_MTD_NAND_YAFFS2) //add yaffs2 file system support
??? if (len_incl_bad == *length) {
??????? rval = nand_write (nand, offset, length, buffer);
??????? if (rval != 0)
??????????? printf ("NAND write to offset %llx failed %d\n",
??????????????? offset, rval);
??????? return rval;
??? }
#endif
??? while (left_to_write > 0) {
??????? size_t block_offset = offset & (nand->erasesize - 1);
??????? size_t write_size;
??????? WATCHDOG_RESET ();
??????? if (nand_block_isbad (nand, offset & ~(nand->erasesize - 1))) {
??????????? printf ("Skip bad block 0x%08llx\n",
??????????????? offset & ~(nand->erasesize - 1));
??????????? offset += nand->erasesize - block_offset;
??????????? continue;
??????? }
#if defined(CONFIG_MTD_NAND_YAFFS2) //add yaffs2 file system support
??????? if(nand->skipfirstblk==1)???
??????? {
??????????? nand->skipfirstblk=0;
??????????? printf ("Skip the first good block %llx\n", offset & ~(nand->erasesize - 1));
??????????? offset += nand->erasesize - block_offset;
??????????? continue;
??????? }
#endif
??????? if (left_to_write < (nand->erasesize - block_offset))
??????????? write_size = left_to_write;
??????? else
??????????? write_size = nand->erasesize - block_offset;
??????? printf("\rWriting at 0x%llx -- ",offset); //add yaffs2 file system support
??????? rval = nand_write (nand, offset, &write_size, p_buffer);
??????? if (rval != 0) {
??????????? printf ("NAND write to offset %llx failed %d\n",
??????????????? offset, rval);
??????????? *length -= left_to_write;
??????????? return rval;
??????? }
??????? left_to_write -= write_size;
??????? printf("%d%% is complete.",100-(left_to_write/(*length/100)));
??????? offset += write_size;
#if defined(CONFIG_MTD_NAND_YAFFS2) //add yaffs2 file system support
??????? if(nand->rw_oob==1)???
??????? {
??????????? p_buffer += write_size+(write_size/nand->writesize*nand->oobsize);
??????? }
??????? else???
??????? {
??????????? p_buffer += write_size;
??????? }
#else
??????? p_buffer += write_size;
#endif
??? }
??? return 0;
}
⑤、在第四步nand_write_skip_bad函数中我们看到又对nand_write函数进行了访问,所以这一步是到nand_write函数中添加对yaffs2的支持,如下:
#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;
}
OK,对yaffs2支持的代码已修改完毕,重新编译u-boot并下载到nand中,启动开发板,在u-boot的命令行输入:nand help查看nand的命令,可以看到多了一个nand write[.yaffs2]的命令,这个就是用来下载yaffs2文件系统到nand中的命令了。
?
⑥、使用nand write[.yaffs2]命令把事前制作好的yaffs2文件系统下载到Nand Flash中(yaffs2文件系统的制作请参考:Linux-2.6.30.4在2440上的移植之文件系统),下载操作步骤和效果图如下:
⑦、结合u-boot和内核来测试启动下载的yaffs2文件系统
设置u-boot启动参数bootargs,注意:这一长串参数要与内核配置里面的Boot options-->Default kernel command string的设置要一致。特别是mtdblock3要根据内核具体的分区来设,在上一篇中讲到了内核中Nand的分区情况,u-boot属于mtdblock0,param属于mtdblock1,kernel属于mtdblock2,root就属于mtdblock3,所以这里要设置成root=/dev/mtdblock3,否则文件系统无法启动成功,会出现一些什么I/O之类的错误
好了,最后重启开发板,内核引导成功,yaffs2文件系统也挂载成功,效果图如下:
?
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
?
#gedit common/cmd_nand.c?? //在U_BOOT_CMD中添加
U_BOOT_CMD(nand, CONFIG_SYS_MAXARGS, 1, do_nand,
??? "NAND sub-system",
??? "info - show available NAND devices\n"
??? "nand device [dev] - show or set current device\n"
??? "nand read - addr off|partition size\n"
??? "nand write - addr off|partition size\n"
??? " read/write 'size' bytes starting at offset 'off'\n"
??? " to/from memory address 'addr', skipping bad blocks.\n"
//注意:这里只添加了yaffs2的写命令,因为我们只用u-boot下载(即写)功能,所以我们没有添加yaffs2读的命令
#if defined(CONFIG_MTD_NAND_YAFFS2)
??? "nand write[.yaffs2] - addr off|partition size - write `size' byte yaffs image\n"
??? "?starting at offset off' from memory address addr' (.yaffs2 for 512+16 NAND)\n"
#endif
??? "nand erase [clean] [off size] - erase 'size' bytes from\n"
??? " offset 'off' (entire device if not specified)\n"
??? "nand bad - show bad blocks\n"
??? "nand dump[.oob] off - dump page\n"
??? "nand scrub - really clean NAND erasing bad blocks (UNSAFE)\n"
??? "nand markbad off [...] - mark bad block(s) at offset (UNSAFE)\n"
??? "nand biterr off - make a bit error at offset (UNSAFE)"
#ifdef CONFIG_CMD_NAND_LOCK_UNLOCK
??? "\n"
??? "nand lock [tight] [status]\n"
??? " bring nand to lock state or display locked pages\n"
??? "nand unlock [offset] [size] - unlock section"
#endif
);
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