Re: [PATCH v2 05/12] mtd: nand: use new BBT API instead of old ones

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Tue, 15 Dec 2015 05:59:31 +0000
Peter Pan <peterpansjtu@gmail.com> wrote:

> From: Brian Norris <computersforpeace@gmail.com>
> 
> Use new BBT APIs (nand_bbt_*()) in NAND. Keep old APIs (nand_*_bbt())
> exist temporarily.
> 
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
> [Peter: 1. use nand_bbt_markbad_factory() in docg4.c and implement
>         2. nand_create_factory_badblock_pattern(), nand_is_bad_bbm() and
>         nand_default_bbt() in nand_base.c
>         3. add NAND_BADBLOCK_PATTERN_ALLOC macro]
> Signed-off-by: Peter Pan <peterpandong@micron.com>
> ---
>  drivers/mtd/nand/docg4.c     |   6 +-
>  drivers/mtd/nand/nand_base.c | 140 ++++++++++++++++++++++++++++++++++++++++---
>  include/linux/mtd/nand.h     |   9 ++-
>  3 files changed, 143 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/nand/docg4.c b/drivers/mtd/nand/docg4.c
> index da93d7f..1be7fa2 100644
> --- a/drivers/mtd/nand/docg4.c
> +++ b/drivers/mtd/nand/docg4.c
> @@ -1037,7 +1037,7 @@ static int __init read_factory_bbt(struct mtd_info *mtd)
>  	 * operation after device power-up.  The above read ensures it never is.
>  	 * Ugly, I know.
>  	 */
> -	if (nand->bbt == NULL)  /* no memory-based bbt */
> +	if (nand->nand_bbt == NULL)  /* no memory-based bbt */
>  		goto exit;
>  
>  	if (mtd->ecc_stats.failed > eccfailed_stats) {
> @@ -1064,8 +1064,8 @@ static int __init read_factory_bbt(struct mtd_info *mtd)
>  		unsigned long bits = ~buf[i];
>  		for_each_set_bit(bitnum, &bits, 8) {
>  			int badblock = block + 7 - bitnum;
> -			nand->bbt[badblock / 4] |=
> -				0x03 << ((badblock % 4) * 2);
> +			nand_bbt_markbad_factory(nand->nand_bbt,
> +					badblock << nand->bbt_erase_shift);
>  			mtd->ecc_stats.badblocks++;
>  			dev_notice(doc->dev, "factory-marked bad block: %d\n",
>  				   badblock);
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 5aec154..28d7a58 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c

[...]

>  
> +/* NAND BBT helper - erase a block, including reserved blocks */
> +static int nand_bbt_erase_block(struct mtd_info *mtd, loff_t addr)
> +{
> +	struct erase_info einfo;
> +	struct nand_chip *chip = mtd->priv;

nand_chip backpointer is no longer stored in mtd->priv (nand_chip now
embeds its own mtd_info field and we use the container_of trick to
retrieve the nand_chip pointer from the mtd_info pointer).

	struct nand_chip *chip = mtd_to_nand(mtd);

> +
> +	memset(&einfo, 0, sizeof(einfo));
> +	einfo.mtd = mtd;
> +	einfo.addr = addr;
> +	einfo.len = 1ULL << chip->phys_erase_shift;
> +
> +	return nand_erase_nand(mtd, &einfo, 1);
> +}
> +

[...]

> +static int nand_is_bad_bbm(struct mtd_info *mtd, loff_t addr)
> +{
> +	struct nand_chip *chip = mtd->priv;

	struct nand_chip *chip = mtd_to_nand(mtd);

> +	struct mtd_oob_ops ops;
> +	struct nand_bbt_descr *bd = chip->badblock_pattern;
> +	int j, ret;
> +	int numpages;
> +
> +	if (bd->options & NAND_BBT_SCAN2NDPAGE)
> +		numpages = 2;
> +	else
> +		numpages = 1;
> +
> +	if (bd->options & NAND_BBT_SCANLASTPAGE)
> +		addr += mtd->erasesize - (mtd->writesize * numpages);
> +
> +	ops.ooblen = mtd->oobsize;
> +	ops.oobbuf = chip->buffers->databuf;
> +	ops.ooboffs = 0;
> +	ops.datbuf = NULL;
> +	ops.mode = MTD_OPS_PLACE_OOB;
> +
> +	for (j = 0; j < numpages; j++) {
> +		/*
> +		 * Read the full oob until read_oob is fixed to handle single
> +		 * byte reads for 16 bit buswidth.
> +		 */
> +		ret = nand_do_read_oob(mtd, addr, &ops);
> +		/* Ignore ECC errors when checking for BBM */
> +		if (ret && !mtd_is_bitflip_or_eccerr(ret))
> +			return ret;
> +
> +		if (memcmp(chip->buffers->databuf + bd->offs,
> +				bd->pattern, bd->len))
> +			return 1;
> +
> +		addr += mtd->writesize;
> +	}
> +
> +	return 0;
> +}
> +
> +static int nand_default_bbt(struct mtd_info *mtd)
> +{
> +	struct nand_chip *chip = mtd->priv;

	struct nand_chip *chip = mtd_to_nand(mtd);

> +	struct nand_bbt *bbt = kzalloc(sizeof(struct nand_bbt), GFP_KERNEL);
> +
> +	if (!bbt)
> +		return -ENOMEM;
> +
> +	bbt->bbt_options = chip->bbt_options;
> +	bbt->mtd = mtd;
> +	bbt->numchips = chip->numchips;
> +	bbt->chipsize = chip->chipsize;
> +	bbt->chip_shift = chip->chip_shift;
> +	bbt->bbt_erase_shift = chip->phys_erase_shift;
> +	bbt->page_shift = chip->page_shift;
> +	bbt->bbt_td = chip->bbt_td;
> +	bbt->bbt_md = chip->bbt_md;
> +	bbt->is_bad_bbm = nand_is_bad_bbm;
> +	bbt->erase = nand_bbt_erase_block;
> +	chip->nand_bbt = bbt;
> +
> +	if (!chip->badblock_pattern &&
> +		nand_create_factory_badblock_pattern(chip))
> +		return -ENOMEM;
> +
> +	return nand_bbt_init(chip->nand_bbt);
> +}



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com