[U-Boot] [RFC 04/11] mtd/nand: add page status table (pst)

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

On Fri,  5 Jun 2015 13:52:37 +0200
Roy Spliet <r.spliet@ultimaker.com> wrote:

Ditto (this work hasn't been accepted in Linux).

> From: yassin <yassinjaffer@gmail.com>
> 
> Signed-off-by: Roy Spliet <r.spliet@ultimaker.com>
> ---
>  drivers/mtd/nand/nand_base.c | 154 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mtd/nand.h     |  21 ++++++
>  2 files changed, 175 insertions(+)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index dbeb092..1c514a0 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -1185,6 +1185,138 @@ EXPORT_SYMBOL(nand_lock);
>  #endif
>  
>  /**
> + * nand_page_is_empty - check wether a NAND page contains only FFs
> + * @mtd:	mtd info
> + * @data:	data buffer
> + * @oob:	oob buffer
> + *
> + * Reads the data stored in the databuf buffer and check if it contains only
> + * FFs.
> + *
> + * Return true if it does else return false.
> + */
> +bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob)
> +{
> +	u8 *buf;
> +	int length;
> +	u32 pattern = 0xffffffff;
> +	int bitflips = 0;
> +	int cnt;
> +
> +	buf = data;
> +	length = mtd->writesize;
> +	while (length) {
> +		cnt = length < sizeof(pattern) ? length : sizeof(pattern);
> +		if (memcmp(&pattern, buf, cnt)) {
> +			int i;
> +			for (i = 0; i < cnt * 8; i++) {
> +				if (!(buf[i / 8] &
> +				      (1 << (i % 8)))) {
> +					bitflips++;
> +					if (bitflips > mtd->ecc_strength)
> +						return false;
> +				}
> +			}
> +		}
> +
> +		buf += sizeof(pattern);
> +		length -= sizeof(pattern);
> +	}
> +
> +	buf = oob;
> +	length = mtd->oobsize;
> +	while (length) {
> +		cnt = length < sizeof(pattern) ? length : sizeof(pattern);
> +		if (memcmp(&pattern, buf, cnt)) {
> +			int i;
> +			for (i = 0; i < cnt * 8; i++) {
> +				if (!(buf[i / 8] &
> +				      (1 << (i % 8)))) {
> +					bitflips++;
> +					if (bitflips > mtd->ecc_strength)
> +						return false;
> +				}
> +			}
> +		}
> +
> +		buf += sizeof(pattern);
> +		length -= sizeof(pattern);
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(nand_page_is_empty);
> +
> +/**
> + * nand_page_get_status - retrieve page status from the page status table (pst)
> + * @mtd:	mtd info
> + * @page:	page you want to get status on
> + *
> + * Return the page status.
> + */
> +int nand_page_get_status(struct mtd_info *mtd, int page)
> +{
> +	struct nand_chip *chip = mtd->priv;
> +	u8 shift = (page % 4) * 2;
> +	uint64_t offset = page / 4;
> +	int ret = NAND_PAGE_STATUS_UNKNOWN;
> +
> +	if (chip->pst)
> +		ret = (chip->pst[offset] >> shift) & 0x3;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(nand_page_get_status);
> +
> +/**
> + * nand_page_set_status - assign page status from in the page status table
> + * @mtd:	mtd info
> + * @page:	page you want to get status on
> + * @status:	new status to assign
> + */
> +void nand_page_set_status(struct mtd_info *mtd, int page,
> +			  enum nand_page_status status)
> +{
> +	struct nand_chip *chip = mtd->priv;
> +	u8 shift;
> +	uint64_t offset;
> +
> +	if (!chip->pst)
> +		return;
> +
> +	shift = (page % 4) * 2;
> +	offset = page / 4;
> +	chip->pst[offset] &= ~(0x3 << shift);
> +	chip->pst[offset] |= (status & 0x3) << shift;
> +}
> +EXPORT_SYMBOL(nand_page_set_status);
> +
> +/**
> + * nand_pst_create - create a page status table
> + * @mtd:	mtd info
> + *
> + * Allocate a page status table and assign it to the mtd device.
> + *
> + * Returns 0 in case of success or -ERRNO in case of error.
> + */
> +int nand_pst_create(struct mtd_info *mtd)
> +{
> +	struct nand_chip *chip = mtd->priv;
> +
> +	if (chip->pst)
> +		return 0;
> +
> +	chip->pst = kzalloc(mtd->size >>
> +			    (chip->page_shift + mtd->subpage_sft + 2),
> +			    GFP_KERNEL);
> +	if (!chip->pst)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(nand_pst_create);
> +
> +/**
>   * nand_read_page_raw - [INTERN] read raw page data without ecc
>   * @mtd: mtd info structure
>   * @chip: nand chip info structure
> @@ -2521,6 +2653,7 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
>  		int bytes = mtd->writesize;
>  		int cached = writelen > bytes && page != blockmask;
>  		uint8_t *wbuf = buf;
> +		int subpage;
>  
>  		WATCHDOG_RESET();
>  		/* Partial page write? */
> @@ -2547,6 +2680,14 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
>  		if (ret)
>  			break;
>  
> +		for (subpage = column / chip->subpagesize;
> +		     subpage < (column + writelen) / chip->subpagesize;
> +		     subpage++)
> +			nand_page_set_status(mtd,
> +					     (page << mtd->subpage_sft) +
> +					     subpage,
> +					     NAND_PAGE_FILLED);
> +
>  		writelen -= bytes;
>  		if (!writelen)
>  			break;
> @@ -2804,6 +2945,7 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
>  	int page, status, pages_per_block, ret, chipnr;
>  	struct nand_chip *chip = mtd->priv;
>  	loff_t len;
> +	int i;
>  
>  	pr_debug("%s: start = 0x%012llx, len = %llu\n",
>  			__func__, (unsigned long long)instr->addr,
> @@ -2880,6 +3022,18 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
>  			goto erase_exit;
>  		}
>  
> +		for (i = 0; i < pages_per_block; i++) {
> +			int subpage;
> +			for (subpage = 0;
> +			     subpage < 1 << mtd->subpage_sft;
> +			     subpage++) {
> +				nand_page_set_status(mtd,
> +					((page + i) << mtd->subpage_sft) +
> +					subpage,
> +					NAND_PAGE_EMPTY);
> +			}
> +		}
> +
>  		/* Increment page address and decrement length */
>  		len -= (1ULL << chip->phys_erase_shift);
>  		page += pages_per_block;
> diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
> index 0cdb3b9..ef6a783 100644
> --- a/include/linux/mtd/nand.h
> +++ b/include/linux/mtd/nand.h
> @@ -547,6 +547,24 @@ struct nand_ecc_ctrl {
>  			int page);
>  };
>  
> +/*
> + * Constants for page status
> + */
> +enum nand_page_status {
> +	NAND_PAGE_STATUS_UNKNOWN,
> +	NAND_PAGE_EMPTY,
> +	NAND_PAGE_FILLED,
> +};
> +
> +bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob);
> +
> +int nand_page_get_status(struct mtd_info *mtd, int page);
> +
> +void nand_page_set_status(struct mtd_info *mtd, int page,
> +			  enum nand_page_status status);
> +
> +int nand_pst_create(struct mtd_info *mtd);
> +
>  /**
>   * struct nand_buffers - buffer structure for read/write
>   * @ecccalc:	buffer pointer for calculated ECC, size is oobsize.
> @@ -660,6 +678,7 @@ struct nand_buffers {
>   * @bbt_md:		[REPLACEABLE] bad block table mirror descriptor
>   * @badblock_pattern:	[REPLACEABLE] bad block scan pattern used for initial
>   *			bad block scan.
> + * @pst:		[INTERN] page status table
>   * @controller:		[REPLACEABLE] a pointer to a hardware controller
>   *			structure which is shared among multiple independent
>   *			devices.
> @@ -750,6 +769,8 @@ struct nand_chip {
>  
>  	struct nand_bbt_descr *badblock_pattern;
>  
> +	uint8_t *pst;
> +
>  	void *priv;
>  };
>  



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