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
9)实现u-boot对yaffs/yaffs2文件系统下载的支持。
注意:此篇对Nand的操作是基于MTD架构方式,在“u-boot-2009.08在2440上的移植详解(三)”中讲到过。
通常一个Nnad Flash存储设备由若干块组成,1个块由若干页组成。一般128MB以下容量的Nand Flash芯片,一页大小为528B,被依次分为2个256B的主数据区和16B的额外空间;128MB以上容量的Nand Flash芯片,一页大小通常为2KB。由于Nand Flash出现位反转的概率较大,一般在读写时需要使用ECC进行错误检验和恢复。
Yaffs/yaffs2文件系统的设计充分考虑到Nand Flash以页为存取单位等的特点,将文件组织成固定大小的段(Chunk)。以528B的页为例,Yaffs/yaffs2文件系统使用前512B存储数据和16B的额外空间存放数据的ECC和文件系统的组织信息等(称为OOB数据)。通过OOB数据,不但能实现错误检测和坏块处理,同时还可以避免加载时对整个存储介质的扫描,加快了文件系统的加载速度。以下是Yaffs/yaffs2文件系统页的结构说明:
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。
实现对Yaffs或者Yaffs2文件系统的读写支持步骤如下:
①、在include/configs/my2440.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:
#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:
![U-boot在S3C2440上的移植详解(五)_第1张图片](http://img.e-com-net.com/image/info5/33a2dd6de7d6412cbce82f646f9e1f3f.png)
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
![U-boot在S3C2440上的移植详解(五)_第2张图片](http://img.e-com-net.com/image/info5/dc425c6c3e8845868661d2a51baa6153.png)
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:
![U-boot在S3C2440上的移植详解(五)_第3张图片](http://img.e-com-net.com/image/info5/ed49d706f4d04007a7593b211f9015da.png)
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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