移植u-boot-2010.09到三星SC32442平台（三）：yaffs2文件系统写入支持

紧接前两篇文章：

7.加入yaffs2文件系统写入支持
这部分与2440上的移植内容基本一致，如下：
1），include/configs/board2442.h头文件中定义一个管理对Yaffs2支持的宏和开启u-boot中对Nand Flash默认分区的宏，如下：//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内核中的分区保持一致

#define MTDIDS_DEFAULT "nand0=nandflash0"
#define MTDPARTS_DEFAULT "mtdparts=nandflash0:256k(bootloader)," /
"128k(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：

修改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
);

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：
修改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：
修改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：

修改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;
}

之后重新编译，启动后，即可以用 nand write.yaffs2 [mem addr] [off] [size]命令写入yaffs2文件系统。不过在第一次写文件系统时，出现了Attempt to write error length data!的错误。查看一下代码，发现是文件系统大小无法被(nand->oobsize+nand->writesize)整除，而出现了报错。再上网查找了一下，找到了原因。原来2440的nand一页是512字节，oobsize是16，所以文件系统大小是512+16=528的倍数。而现在的2442用的是128M的大页nand，一页2048字节，oobsize是64字节，2048+64=2112字节，所以写入文件系统大小应该是2112的倍数才不会出错。这说明制作文件系统时选用的工具选错了，应该选用针对128M大页nand的工具。我找到了当时下的mkyaffs2image工具，发现压缩包里还有mkyaffs2image-128M另外一个程序，用这个程序重新制作了下文件系统，写入nand，就没问题了。