mtd分层调用流程

小鱼儿 2021-11-22 10:08 264阅读 0赞

原文网址：[mtd分层调用流程\_IT利刃出鞘的博客-CSDN博客][mtd_IT_-CSDN]

# 字符节点分层调用流程 #

示例：nanddump -p -c -l 0x800 /dev/mtd8

## open ##

open(“/dev/mtd8”...) = 3  
mtdchar\_open(struct inode \*inode, struct file \*file) //mtdchar.c  
int minor = iminor(inode);  
int devnum = minor >> 1;  
struct mtd\_info \*mtd;  
struct mtd\_file\_info \*mfi;

mtd = get\_mtd\_device(NULL, devnum);  
struct mtd\_info \*ret = NULL  
ret = idr\_find(&mtd\_idr, num);  
\_\_get\_mtd\_device(ret);  
return ret;

mfi = kzalloc(sizeof(\*mfi), GFP\_KERNEL);  
mfi->mtd = mtd;  
file->private\_data = mfi;

ioctl

ioctl(3, MIXER\_READ(18) or ECCGETSTATS, ...)  
struct mtd\_file\_info \*mfi = file->private\_data;  
struct mtd\_info \*mtd = mfi->mtd;

检查坏块：MEMSETBADBLOCK  
擦除：MEMERASE、MEMERASE64

## 擦除 ##

mtd\_erase(mtd, erase); //mtdcore.c  
mtd->\_erase(mtd, instr) //nand\_base.c=>nand\_scan\_tail中指定的  
nand\_erase(mtd, instr); //nand\_base.c  
nand\_erase\_nand(mtd, instr, 0) //nand\_base.c  
chip->select\_chip(mtd, chipnr); //控制器驱动或nand\_base.c=>nand\_scan\_ident中指定  
nand\_block\_checkbad(mtd, ((loff\_t) page) << chip->page\_shift, allowbbt) //若是坏块，则不擦除  
if (!chip->bbt) //否则 return nand\_isbad\_bbt(mtd, ofs, allowbbt); nand\_bbt.c  
chip->block\_bad(mtd, ofs); //nand\_base.c=> nand\_scan\_ident=> nand\_set\_defaults  
nand\_block\_bad(mtd, ofs) //nand\_base.c  
如果(chip->bbt\_options & NAND\_BBT\_SCANLASTPAGE)  
ofs += mtd->erasesize - mtd->writesize;  
chip->cmdfunc(mtd, NAND\_CMD\_READOOB, chip->badblockpos, page);  
bad = chip->read\_byte(mtd);  
res = bad != 0xFF;  
如果(chip->bbt\_options & NAND\_BBT\_SCAN2NDPAGE)  
会再读下一页的bb数据  
return res;  
chip->erase(mtd, page & chip->pagemask) //nand\_base.c=> nand\_get\_flash\_type中指定  
single\_erase(mtd, page & chip->pagemask)  
//控制器驱动或nand\_base.c=>nand\_scan\_ident中指定  
chip->cmdfunc(mtd, NAND\_CMD\_ERASE1, -1, page);  
发送页地址  
chip->cmdfunc(mtd, NAND\_CMD\_ERASE2, -1, -1);

## 读 ##

read(3, ...) //应用层

mtdchar\_read(struct file \*file, char \_\_user \*buf, size\_t count, loff\_t \*ppos) //mtdchar.c  
//一般走switch的默认路径  
struct mtd\_file\_info \*mfi = file->private\_data;  
struct mtd\_info \*mtd = mfi->mtd;  
ret = mtd\_read(mtd, \*ppos, len, &retlen, kbuf); //mtdcore.c  
ret\_code = mtd->\_read(mtd, from, len, retlen, buf); //mtdpart.c=> allocate\_partition指定  
 part\_read(mtd, from, len, retlen, buf); //mtdpart.c  
stats = part->master->ecc\_stats;  
res = part->master->\_read(part->master, from + part->offset, len, retlen, buf);  
//nand\_base.c=>nand\_scan\_tail指定  
nand\_read(mtd, from, len, retlen, buf) //nand\_base.c  
ops.mode = MTD\_OPS\_PLACE\_OOB;  
nand\_do\_read\_ops(mtd, from, &ops); //nand\_base.c  
uint8\_t \*oob;  
oob = ops->oobbuf;  
ecc\_failures = mtd->ecc\_stats.failed;  
chip->select\_chip(mtd, chipnr);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident => nand\_set\_defaults  
chip->cmdfunc(mtd, NAND\_CMD\_READ0, 0x00, page);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident => nand\_set\_defaults  
**发送地址、读命令**  
如果ops->mode是MTD\_OPS\_RAW  
ret = chip->ecc.read\_page\_raw(mtd, chip, bufpoi,  
oob\_required, page);  
//nand\_base.c=>nand\_scan\_tail函数中设置  
若没对齐 且 chip->options有NAND\_SUBPAGE\_READ 且  
ops->oobbuf是NULL  
ret = chip->ecc.read\_subpage(mtd, chip, col,  
bytes, bufpoi, page);  
其他 //一般走此分支  
ret = chip->ecc.read\_page(mtd, chip, bufpoi, oob\_required, page);  
ret = chip->ecc.read\_page(mtd, chip, bufpoi, oob\_required, page);  
//nand\_base.c=> nand\_scan\_tail指定  
nand\_read\_page\_raw(mtd, chip, bufpoi, oob\_required, page)  
//nand\_base.c  
//此函数返回值一定为0  
chip->read\_buf(mtd, buf, mtd->writesize);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident =>  
//nand\_set\_defaults指定  
**只是把host->buf数据拷贝到buf**  
hisi\_fmc\_read\_buf(struct mtd\_info \*mtd,  
uint8\_t \*buf, int len)  
如果读失败了：mtd->ecc\_stats.failed++;  
设置ECC纠正的位数：mtd->ecc\_stats.corrected += ..

max\_bitflips = max\_t(unsigned int, max\_bitflips, ret);  
if(oob)  
oob = nand\_transfer\_oob(mtd, oob, ops, toread);  
//如果ecc出错了，重传  
if (mtd->ecc\_stats.failed - ecc\_failures)  
//如果还有剩余尝试次数，重传  
if (retry\_mode + 1 < chip->read\_retries)\{  
mtd->ecc\_stats.failed = ecc\_failures;  
goto read\_retry;  
\}else\{  
ecc\_fail = true;  
\}  
\}  
  
if (ret < 0)  
return ret;

if (ecc\_fail)  
return -EBADMSG;

return max\_bitflips;  
if ((mtd\_is\_eccerr(res)))  
mtd->ecc\_stats.failed += part->master->ecc\_stats.failed - stats.failed;  
else  
mtd->ecc\_stats.corrected += part->master->ecc\_stats.corrected - stats.corrected;  
若ret\_code < 0，直接返回  
若mtd->ecc\_strength == 0，直接返回0  
若ret\_code大于mtd->bitflip\_threshold  
返回-EUCLEAN  
否则  
返回0  
 如果读出错了（ret != 0）  
ret = mtd\_is\_bitflip\_or\_eccerr(ret) //mtd.h  
return mtd\_is\_bitflip(err) || mtd\_is\_eccerr(err)  
如果err是-EUCLEAN，是位反转（但被校正过来了）；如果err是-EBADMSG，是ECC错误  
如果ret != 0，拷贝数据给用户

## 写 ##

write(3, ...)  
mtdchar\_write(struct file \*file, const char \_\_user \*buf, size\_t count, loff\_t \*ppos) //mtdchar.c  
//默认走default流程  
mtd\_write(mtd, \*ppos, len, &retlen, kbuf); //mtdcore.c  
mtd->\_write(mtd, to, len, retlen, buf); //nand\_base.c=>nand\_scan\_tail中指定的  
nand\_write(mtd, to, len, retlen, buf); //nand\_base.c  
ops.mode = MTD\_OPS\_PLACE\_OOB;  
nand\_do\_write\_ops(mtd, to, &ops); //nand\_base.c  
chip->select\_chip(mtd, chipnr);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident => nand\_set\_defaults中指定  
chip->write\_page(mtd, chip, column, ..., (ops->mode == MTD\_OPS\_RAW))  
//控制器驱动或**nand\_base.c=>nand\_scan\_tail**指定。的）  
nand\_write\_page //nand\_base.c  
chip->cmdfunc(mtd, NAND\_CMD\_SEQIN, 0x00, page);  
**设置写的地址**  
如果是raw,走chip->ecc.write\_page\_raw;  
如果支持subpage，走chip->ecc.write\_subpage；  
其他：（**一般走此分支**）  
chip->ecc.write\_page(mtd, chip, buf, oob\_required, page);  
//nand\_base.c=>nand\_scan\_tail指定  
nand\_write\_page\_raw(mtd, chip, buf, oob\_required, page); //nand\_base.c  
chip->write\_buf(mtd, buf, mtd->writesize);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident => nand\_set\_defaults  
**只是将数据复制到host->buffer**  
chip->cmdfunc(mtd, NAND\_CMD\_PAGEPROG, -1, -1);  
//**控制器驱动**或nand\_base.c=>nand\_scan\_ident => nand\_set\_defaults指定  
**执行烧写命令**

[mtd_IT_-CSDN]: https://knife.blog.csdn.net/article/details/97155041