mtd设备操作、jffs2

安装mtd相关命令
手动安装mtd-utils，根据系统自行选择

mtd交叉编译：https://blog.csdn.net/zhangxuechao_/article/details/52124424

系统flash操作命令

# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00080000 00020000 "boot"
mtd1: 00100000 00020000 "kernel"
mtd2: 00580000 00020000 "roofs"
mtd3: 00900000 00020000 "app"

# flash_erase device [start] [cnt] 
# flash_erase /dev/mtd0 0×40000 5

start：起始位置。必须为0x20000(128K)的整数倍
cnt：块数

# flash_eraseall [OPTION] device 
# flash_eraseall -j /dev/mtd0

-j，jffs2：jffs2格式化分区
-q，quiet：不显示打印信息

# flash_eraseall -j -q /dev/mtd0 = flash_erase /dev/mtd0 0 0

新版擦除整个设备，已建议使用flash_erase

# mount -t jffs2 /dev/mtdblock0 /mnt

挂载mtd设备。mtdblock只用于挂载，/dev/mtd操作实际就是操作/dev/mtdblock

# flashcp <filename> <device>
# flashcp fs.jffs2 /dev/mtd0

# mtd_debug info <device>
# mtd_debug info /dev/mtd0
mtd.type = MTD_NORFLASH
mtd.flags = 
mtd.size = 12582912 (12M)
mtd.erasesize = 131072 (128K)
mtd.oobblock = 1 
mtd.oobsize = 0 
mtd.ecctype = (unknown ECC type - new MTD API maybe?)
regions = 0
# mtd_debug read /dev/mtd2 0 100 file.dest

uboot flash操作
对Nand flash对应mtd分区擦除时。擦除要擦除整个设备大小；写要写jffs2文件系统大小。不然数据可能会有问题，可能原因是jffs2格式写入位置

# nand erase 0x4100000 0x200000 //擦除整个mtd分区2M
# nand write 0x6000000 0x4100000 0x20000 //写入128K

uboot flash按分区操作

> mtddevice nand0 <nandflash0>, # parts = 4#: name                        size            offset          mask_flags0: bootloader          0x00040000      0x00000000      01: params              0x00020000      0x00040000      02: kernel              0x00200000      0x00060000      03: root                0x0fda0000      0x00260000      0> nand erase rootNAND erase: device 0 offset 0x260000, size 0xfda0000                                         
Erasing at 0xffe0000 -- 100% complete.
OK> nand write.jffs2 0x3000000 rootNAND write: device 0 offset 0x260000, size 0xfda00000xfda0000 bytes written: OK

filesize文件大小

> nand write.jffs2 0x3000000 0x260000 $(filesize)NAND write: device 0 offset 0x260000, size 0x15787a8Writing data at 0x17f8000 -- 100% complete.22513576 bytes written: OK

举例

#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include "mtd-user.h"int non_region_erase(int fd, int start, int count, int unlock)
{mtd_info_t meminfo;if(ioctl(fd, MEMGETINFO, &meminfo) == 0){erase_info_t erase;erase.start = start;erase.length = meminfo.erasesize;for(; count > 0; count--){printf("\rPerforming Flash Erase of length %u at offset 0x%x\n", erase.length, erase.start);fflush(stdout);if(unlock != 0){//unlock the sector firstprintf("\rPerforming Flash unlock at offset 0x%x\n", erase.start);if(ioctl(fd, MEMUNLOCK, &erase) != 0){perror("MTD Unlock failure");close(fd);return -1;}}if(ioctl(fd, MEMERASE, &erase) != 0){perror("MTD Erase failure");close(fd);return -1;}erase.start += meminfo.erasesize;}printf("done!\n");}return 0;
}int main(int argc, char *argv[])
{int fd, ret, i;struct mtd_info_user info;// Open the deviceif((fd = open("/dev/mtd5", O_RDWR)) < 0){fprintf(stderr, "File open error\n");return -1;}else{ioctl(fd, MEMGETINFO, &info);printf("info.size=%d\n", info.size);printf("info.erasesize=%d\n", info.erasesize);printf("info.writesize=%d\n", info.writesize);printf("info.oobsize=%d\n", info.oobsize);}struct stat st;//check is a char deviceret = fstat(fd, &st);if(ret < 0){printf("fstat %s failed!\n", FLASH_DEV_NAME);close(fd);return -1;}if(!S_ISCHR(st.st_mode)){printf("%s: not a char device\n", FLASH_DEV_NAME);close(fd);return -1;}#if 0ret = non_region_erase(fd, 0, 1, 0);if(ret < 0){return -1;}#endifchar *pReadBuf;int nReadBytes;nReadBytes = info.erasesize;pReadBuf = malloc(nReadBytes);memset(pReadBuf, 0, nReadBytes);ret = read(fd, pReadBuf, 256);printf("%s--read %d bytes from mtd\n", __func__, ret);for(i = 0; i < ret; i++){printf("%02x,", *(pReadBuf + i));}printf("\n");free(pReadBuf);
}

详细操作，参考mtd源码mtd_debug.c