[PATCH 11/15] MTD: nand: add ->badblockbits to specify the minimum number of bits in bad block byte to consider the block good

Maxim Levitsky
2010-02-22T18:40:33Z

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

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
---
drivers/mtd/nand/nand_base.c | 13 +++++++++----
include/linux/mtd/nand.h | 1 +
2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 51dfea1..ba29a29 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -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;
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 48bc2c5..f2d4a1a 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -401,6 +401,7 @@ struct nand_chip {
int subpagesize;
uint8_t cellinfo;
int badblockpos;
+ int badblockbits;

flstate_t state;

--
1.6.3.3