Commit e0b58d0a authored by Maxim Levitsky's avatar Maxim Levitsky Committed by David Woodhouse
Browse files

mtd: nand: add ->badblockbits for minimum number of set bits in bad block byte 



This can be used to protect against bitflips in that field, but now mostly
for smartmedia.

Signed-off-by: default avatarMaxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent b64d39d8

drivers/mtd/nand/nand_base.c

+9 −4
Original line number Diff line number Diff line
@@ -364,14 +364,18 @@ static int nand_block_bad(struct mtd_info *mtd, loff_t ofs, int getchip) 
		bad = cpu_to_le16(chip->read_word(mtd));

		if (chip->badblockpos & 0x1)

			bad >>= 8;

		if ((bad & 0xFF) != 0xff)

			res = 1;

		else

			bad &= 0xFF;

	} else {

		chip->cmdfunc(mtd, NAND_CMD_READOOB, chip->badblockpos, page);

		if (chip->read_byte(mtd) != 0xff)

			res = 1;

		bad = chip->read_byte(mtd);

	}



	if (likely(chip->badblockbits == 8))

		res = bad != 0xFF;

	else

		res = hweight8(bad) < chip->badblockbits;



	if (getchip)

		nand_release_device(mtd);
@@ -2884,6 +2888,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd, 
	/* Set the bad block position */

	chip->badblockpos = mtd->writesize > 512 ?

		NAND_LARGE_BADBLOCK_POS : NAND_SMALL_BADBLOCK_POS;

	chip->badblockbits = 8;



	/* Get chip options, preserve non chip based options */

	chip->options &= ~NAND_CHIPOPTIONS_MSK;

include/linux/mtd/nand.h

+1 −0
Original line number Diff line number Diff line
@@ -401,6 +401,7 @@ struct nand_chip { 
	int		subpagesize;

	uint8_t		cellinfo;

	int		badblockpos;

	int		badblockbits;



	flstate_t	state;