在应用程序中实现对NandFlash的操…

在应用程序中实现对NandFlash的操作

打开设备

获取设备信息

__u32 erasesize;
__u32 writesize;
__u32 oobsize;// Amount of OOB data per block (e.g. 16)

__u32 ecctype;
__u32 eccsize;
};

struct mtd_info_user mtd;

擦除NandFlash

写NandFlash

struct mtd_oob_buf {
__u32 start;
__u32 length;
unsigned char *ptr;
};int nandwrite(DeviceInfo* meminfo)
{
int imglen = 0, pagelen;
bool baderaseblock = false;
int blockstart = -1;
loff_t offs;
int ret, readlen;
unsigned char tmp_oob[32];//OOB A/B/C/D,一共32字节
struct mtd_oob_buf OOB_INFO ;
sourceaddr = meminfo->head->file_offset;   //要读的部分在镜像文件中的偏移量
sourcelen = meminfo->head->size;           //要读的部分的大小
int num_to_read = 0;OOB_INFO.start = 0;
OOB_INFO.length = meminfo->head->oob_usr_length;   //32字节，用户可以访问的OOB的大小，也就是OOB A/B/C/D
OOB_INFO.ptr = tmp_oob;pagelen = meminfo->writesize; // 2KB
imglen = sourcelen;           // 镜像文件的长度mtdoffset = meminfo->head->flash_offset;  //要写的部分在/dev/mtdx中的偏移量，以字节为单位if (0 == sourceaddr) {
DEBUG("Have no sourceaddr return ****************************\n");
return 1;
}// Check, if length fits into device
if ( ((imglen / pagelen) * meminfo->writesize) > (meminfo->size - mtdoffset)) {
fprintf (stderr, "Image %d bytes, NAND page %d bytes, OOB area %u bytes, device size %u bytes\n",
imglen, pagelen, meminfo->writesize, meminfo->size);
perror ("Input file does not fit into device");
goto closeall;
}while ((imglen>0) && (mtdoffset < meminfo->size))
{
//blockstart 将来存放的是正在写的那块的起始地址，并且是块对齐的
//mtdoffset 表示的是在某个mtd设备中的整体偏移量，可以按块递增，也可以按页递增
//设置blockstart的目的是:
// 假如检测到一个好的块，开始进行写操作，但是在写的过程中发生了写错误，可以认为这块已经
//是坏块了，需要重新再找一个好的块，然后重新写入之前的数据，因此需要知道刚才那个坏块的起始地址
// mtdoffset & (~meminfo->erasesize + 1) 这种获取块起始地址的算法值得借鉴
while (blockstart != (mtdoffset & (~meminfo->erasesize + 1)))
{
blockstart = mtdoffset & (~meminfo->erasesize + 1);
offs = blockstart;
baderaseblock = false;
if (!quiet)
{
fprintf (stderr, "\rWriting data to block %d at offset 0x%x", \
blockstart / meminfo->erasesize, blockstart);
}// meminfo->fd 是某个/dev/mtdx的文件描述符
do {
if ((ret = ioctl(meminfo->fd, MEMGETBADBLOCK, &offs)) < 0)
{
perror("ioctl(MEMGETBADBLOCK)");
goto closeall;
}
if (ret == 1)
{
baderaseblock = true;
if (!quiet)
{
fprintf (stderr, "Bad block at %x block(s) "
"from %x will be skipped\n",
(int) offs, blockstart);
}
}
if (baderaseblock)
{
mtdoffset = blockstart + meminfo->erasesize;
}
offs +=  meminfo->erasesize;
} while ( offs < blockstart + meminfo->erasesize );}readlen = meminfo->writesize;  // 2KBif (0 != sourceaddr)
{
if((meminfo->head->imageType == YAFFS) || (meminfo->head->imageType == OOB_RAW))
{
writeoob = true;
}
else
{
writeoob = false;
}memset(writebuf, 0xff, sizeof(writebuf));if(imglen <<span style="font-family: 'Courier New' !important; font-size: 12px !important;"> readlen)
{
num_to_read = imglen;
}
else
{
num_to_read = readlen;
}// 从镜像文件中偏移量为sourceaddr处读取num_to_read个字节到writebuf中
// ALLIMAGEFD 为镜像文件的文件描述符
if(pread(ALLIMAGEFD, writebuf, num_to_read, sourceaddr) < 0)
{
perror("fail to pread\n");
return -1;
}sourceaddr += num_to_read;if(writeoob)
{
memset(tmp_oob, 0xff , OOB_FREE_MAX);
// 从镜像文件中偏移量为sourceaddr+meminfo->head->oob_usr_offset处读取meminfo->head->oob_usr_length个字节到tmp_oob中，其中meminfo->head->oob_usr_offset是OOB A相对与OOB区域的偏移量，meminfo->head->oob_usr_length 在本例中为32字节
if(pread(ALLIMAGEFD, tmp_oob, meminfo->head->oob_usr_length, sourceaddr+meminfo->head->oob_usr_offset) < 0)
{
perror("fail to pread\n");
return -1;
}
sourceaddr += meminfo->oobsize;}}if(-1 == pwrite(meminfo->fd, writebuf, meminfo->writesize, mtdoffset)) //写NandFlash
{int rewind_blocks;
off_t rewind_bytes;
erase_info_t erase;perror("ioctl(MEMEWRITEPAGE)");rewind_blocks = (mtdoffset - blockstart) / meminfo->writesize;
rewind_bytes = (rewind_blocks * meminfo->writesize) + readlen;
if (writeoob)
{
rewind_bytes += (rewind_blocks + 1) * meminfo->oobsize;
}
sourceaddr -= rewind_bytes;
erase.start = blockstart;
erase.length = meminfo->erasesize;
fprintf(stderr, "Erasing failed write from lx-lx\n",
(long)erase.start, (long)erase.start+erase.length-1);
if (ioctl(meminfo->fd, MEMERASE, &erase) != 0)
{
perror("MEMERASE");
goto closeall;
}if (markbad)
{
loff_t bad_addr = mtdoffset & (~meminfo->erasesize + 1);
fprintf(stderr, "Marking block at lx bad\n", (long)bad_addr);
if (ioctl(meminfo->fd, MEMSETBADBLOCK, &bad_addr)) {
perror("MEMSETBADBLOCK");}
}
mtdoffset = blockstart + meminfo->erasesize;
imglen += rewind_blocks * meminfo->writesize;
if(writeoob)
{
imglen += rewind_blocks * meminfo->oobsize;
}continue;
}imglen -= readlen;
if(writeoob)
{
imglen -= meminfo->oobsize;
OOB_INFO.start = mtdoffset;
if (ioctl(meminfo->fd, MEMWRITEOOB, &OOB_INFO))
{
perror("fail to ioctl");
}
}
mtdoffset += meminfo->writesize;
}closeall:
if ((imglen > 0))
{
perror ("Data was only partially written due to error\n");
exit (EXIT_FAILURE);
}return EXIT_SUCCESS;
}

读OOB

#include
#include
#include
#include
#include
#include
#include
#include <<span style="color: rgb(0, 0, 255); font-family: 'Courier New' !important; font-size: 12px !important;">string.h>
#include#define N 32
#define OFS   (0)
#define block_size (128*1024)
#define page_size  (2*1024)int main(int argc, const char *argv[])
{int fd;
int i, j;unsigned char oob_data[32] =
{
0x53, 0x50, 0x4c, 0x20, 0, 0xff, 0, 0xff,
0x53, 0x50, 0x4c, 0x20, 0, 0xff, 0, 0xff,
0x53, 0x50, 0x4c, 0x20, 0, 0xff, 0, 0xff,
0x53, 0x50, 0x4c, 0x20, 0, 0xff, 0, 0xff
};unsigned char oobbuf
;struct mtd_oob_buf oob = {0, N, oobbuf};
struct mtd_oob_buf my_oob = {0, N, oob_data};fd = open("/dev/mtd0", O_RDWR);
if(fd < 0)
{
perror("fail to open\n");
exit(-1);
}if(ioctl(fd, MEMWRITEOOB, &my_oob))
{
perror("fail to ioctl");
exit(-1);
}memset(oobbuf, 0, sizeof(oobbuf));
oob.start = OFS;
if (ioctl(fd, MEMREADOOB, &oob))
{
perror("fail to ioctl");
exit(-1);
}for(i=0; i)
{
if(i%8 == 0)
{
printf("\n");
}
printf("%#x ", oobbuf[i]);
}printf("\n\n");close (fd);return 0;}