分类： LINUX
2009-03-25 20:57:44
Arm-linux东东nand之9: nand_scan_tail下:
static int scan_block_fast(struct mtd_info *mtd, struct nand_bbt_descr *bd,
loff_t offs, uint8_t *buf, int len)
{
struct mtd_oob_ops ops;
int j, ret;
ops.ooblen = mtd->oobsize;
ops.oobbuf = buf;
ops.ooboffs = 0;
ops.datbuf = NULL;
ops.mode = MTD_OOB_PLACE;
for (j = 0; j < len; j++) {
/*
* Read the full oob until read_oob is fixed to
* handle single byte reads for 16 bit
* buswidth
*/
ret = mtd->read_oob(mtd, offs, &ops);
if (ret)
return ret;
if (check_short_pattern(buf, bd))
return 1;
offs += mtd->writesize;
}
return 0;
}
Len是为2的.也就只要扫描头二页就行了.红色的那一句就是加一页了.
/**
* struct mtd_oob_ops - oob operation operands
* @mode: operation mode
*
* @len: number of data bytes to write/read
*
* @retlen: number of data bytes written/read
*
* @ooblen: number of oob bytes to write/read
* @oobretlen: number of oob bytes written/read
* @ooboffs: offset of oob data in the oob area (only relevant when
* mode = MTD_OOB_PLACE)
* @datbuf: data buffer - if NULL only oob data are read/written
* @oobbuf: oob data buffer
*
* Note, it is allowed to read more then one OOB area at one go, but not write.
* The interface assumes that the OOB write requests program only one page's
* OOB area.
*/
struct mtd_oob_ops {
mtd_oob_mode_t mode;
size_t len;
size_t retlen;
size_t ooblen;
size_t oobretlen;
uint32_t ooboffs;
uint8_t *datbuf;
uint8_t *oobbuf;
};
mtd_oob_ops 可以表示真的数据,也可以表示OOB数据.上面的解释很清楚了.再说你可能要骂我了.
check_short_pattern很简单.只要会C的就能看懂了.
我们看这个mtd->read_oob
记得不在nand_scan_tail中:
mtd->read_oob = nand_read_oob;
…………………………………………………
static int nand_read_oob(struct mtd_info *mtd, loff_t from,
struct mtd_oob_ops *ops)
{
struct nand_chip *chip = mtd->priv;
int ret = -ENOTSUPP;
ops->retlen = 0;
/* Do not allow reads past end of device */
if (ops->datbuf && (from + ops->len) > mtd->size) {
DEBUG(MTD_DEBUG_LEVEL0, "nand_read_oob: "
"Attempt read beyond end of device\n");
return -EINVAL;
}
nand_get_device(chip, mtd, FL_READING);
switch(ops->mode) {
case MTD_OOB_PLACE:
case MTD_OOB_AUTO:
case MTD_OOB_RAW:
break;
default:
goto out;
}
if (!ops->datbuf)
ret = nand_do_read_oob(mtd, from, ops);
else
ret = nand_do_read_ops(mtd, from, ops);
out:
nand_release_device(mtd);
return ret;
}
……………………………………..
我们来说下主要的函数:
关于nand_get_device与nand_release_device这里不表
红色的那段是成立的.于是:
…………………………
static int nand_do_read_oob(struct mtd_info *mtd, loff_t from,
struct mtd_oob_ops *ops)
{
int page, realpage, chipnr, sndcmd = 1;
struct nand_chip *chip = mtd->priv;
int blkcheck = (1 << (chip->phys_erase_shift - chip->page_shift)) - 1;
int readlen = ops->ooblen;
int len;
uint8_t *buf = ops->oobbuf;
DEBUG(MTD_DEBUG_LEVEL3, "nand_read_oob: from = 0x%08Lx, len = %i\n",
(unsigned long long)from, readlen);
if (ops->mode == MTD_OOB_AUTO)
len = chip->ecc.layout->oobavail;
else
len = mtd->oobsize;
if (unlikely(ops->ooboffs >= len)) {
DEBUG(MTD_DEBUG_LEVEL0, "nand_read_oob: "
"Attempt to start read outside oob\n");
return -EINVAL;
}
/* Do not allow reads past end of device */
if (unlikely(from >= mtd->size ||
ops->ooboffs + readlen > ((mtd->size >> chip->page_shift) -
(from >> chip->page_shift)) * len)) {
DEBUG(MTD_DEBUG_LEVEL0, "nand_read_oob: "
"Attempt read beyond end of device\n");
return -EINVAL;
}
chipnr = (int)(from >> chip->chip_shift);
chip->select_chip(mtd, chipnr);
/* Shift to get page */
realpage = (int)(from >> chip->page_shift);
page = realpage & chip->pagemask;
…………………………
MTD_OOB_AUTO没有设的于是.len就等于mtd->oobsize. 那个realpage行吧.记得我以前说过page_shitf不记得回头看下.
……………………
while(1) {
sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);
len = min(len, readlen);
buf = nand_transfer_oob(chip, buf, ops, len);
if (!(chip->options & NAND_NO_READRDY)) {
/*
* Apply delay or wait for ready/busy pin. Do this
* before the AUTOINCR check, so no problems arise if a
* chip which does auto increment is marked as
* NOAUTOINCR by the board driver.
*/
if (!chip->dev_ready)
udelay(chip->chip_delay);
else
nand_wait_ready(mtd);
}
readlen -= len;
if (!readlen)
break;
/* Increment page address */
realpage++;
page = realpage & chip->pagemask;
/* Check, if we cross a chip boundary */
if (!page) {
chipnr++;
chip->select_chip(mtd, -1);
chip->select_chip(mtd, chipnr);
}
/* Check, if the chip supports auto page increment
* or if we have hit a block boundary.
*/
if (!NAND_CANAUTOINCR(chip) || !(page & blkcheck))
sndcmd = 1;
}
………………………………………………………
进入这个while不过只会一次.执行到红色那里就退出了.
因为readlen就等于len;
ops.ooblen = mtd->oobsize;
ops.oobbuf = buf;
ops.ooboffs = 0;
ops.datbuf = NULL;
ops.mode = MTD_OOB_PLACE;
这一句: sndcmd = chip->ecc.read_oob(mtd, chip, page, sndcmd);
对于硬件算ECC的来说就是
…………………
static int nand_read_oob_std(struct mtd_info *mtd, struct nand_chip *chip,
int page, int sndcmd)
{
if (sndcmd) {
chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
sndcmd = 0;
}
chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
return sndcmd;
}
Sndcmd是为1的.发送命令.然后就读.命令如何分发上面已经讲过了.
回到nand_do_read_oob还有一个函数nand_transfer_oob
static uint8_t *nand_transfer_oob(struct nand_chip *chip, uint8_t *oob,
struct mtd_oob_ops *ops, size_t len)
{
switch(ops->mode) {
case MTD_OOB_PLACE:
case MTD_OOB_RAW:
memcpy(oob, chip->oob_poi + ops->ooboffs, len);
return oob + len;
case MTD_OOB_AUTO: {
struct nand_oobfree *free = chip->ecc.layout->oobfree;
uint32_t boffs = 0, roffs = ops->ooboffs;
size_t bytes = 0;
for(; free->length && len; free++, len -= bytes) {
/* Read request not from offset 0 ? */
if (unlikely(roffs)) {
if (roffs >= free->length) {
roffs -= free->length;
continue;
}
boffs = free->offset + roffs;
bytes = min_t(size_t, len,
(free->length - roffs));
roffs = 0;
} else {
bytes = min_t(size_t, len, free->length);
boffs = free->offset;
}
memcpy(oob, chip->oob_poi + boffs, bytes);
oob += bytes;
}
return oob;
}
default:
BUG();
}
return NULL;
}
MTD_OOB_PLACE是设了的.于是只有一个潇潇洒洒的一个函数memcpy
回了,一直返回.这样一次扫描就完了.于在nand_chip中就有一个表来表示那些是坏块了
还有一个函数就是:
int nand_isbad_bbt(struct mtd_info *mtd, loff_t offs, int allowbbt)
{
struct nand_chip *this = mtd->priv;
int block;
uint8_t res;
/* Get block number * 2 */
block = (int)(offs >> (this->bbt_erase_shift - 1));
res = (this->bbt[block >> 3] >> (block & 0x06)) & 0x03;
DEBUG(MTD_DEBUG_LEVEL2, "nand_isbad_bbt(): bbt info for offs 0x%08x: (block %d) 0x%02x\n",
(unsigned int)offs, block >> 1, res);
switch ((int)res) {
case 0x00:
return 0;
case 0x01:
return 1;
case 0x02:
return allowbbt ? 0 : 1;
}
return 1;
}
没有了.就这样了.
万物归宗又回到了s3c24xx_nand_probe
还有一个函数就是s3c2410_nand_add_partition
