[PATCH v5] mtd: nand: toshiba: Add support for Toshiba Memory BENAND (Built-in ECC NAND)

[PATCH v5] mtd: nand: toshiba: Add support for Toshiba Memory BENAND (Built-in ECC NAND)

[KOBAYASHI Yoshitake]

From: yoshitake.kobayashi@toshiba.co.jp

This patch is a patch to support TOSHIBA MEMORY CORPORATION BENAND
memory devices.  Check the status of the built-in ECC with the Read
Status command without using the vendor specific command.  The Read
Status command only knows whether there was bitflips above the
threshold and can not get accurate bitflips.  For now, I set
max_bitflips mtd->bitflip_threshold.

Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
---
 drivers/mtd/nand/raw/nand_toshiba.c | 84 +++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/drivers/mtd/nand/raw/nand_toshiba.c b/drivers/mtd/nand/raw/nand_toshiba.c
index ab43f02..6cec923 100644
--- a/drivers/mtd/nand/raw/nand_toshiba.c
+++ b/drivers/mtd/nand/raw/nand_toshiba.c
@@ -17,6 +17,86 @@
 
 #include <linux/mtd/rawnand.h>
 
+/* Recommended to rewrite for BENAND */
+#define TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED	BIT(3)
+
+static int toshiba_nand_benand_eccstatus(struct mtd_info *mtd,
+					 struct nand_chip *chip)
+{
+	int ret;
+	unsigned int max_bitflips = 0;
+	u8 status;
+
+	/* Check Status */
+	ret = nand_status_op(chip, &status);
+	if (ret)
+		return ret;
+
+	if (status & NAND_STATUS_FAIL) {
+		/* uncorrected */
+		mtd->ecc_stats.failed++;
+	} else if (status & TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED) {
+		/* corrected */
+		max_bitflips = mtd->bitflip_threshold;
+		mtd->ecc_stats.corrected += max_bitflips;
+	}
+
+	return max_bitflips;
+}
+
+static int
+toshiba_nand_read_page_benand(struct mtd_info *mtd,
+			      struct nand_chip *chip, uint8_t *buf,
+			      int oob_required, int page)
+{
+	int ret;
+
+	ret = nand_read_page_raw(mtd, chip, buf, oob_required, page);
+	if (ret)
+		return ret;
+
+	return toshiba_nand_benand_eccstatus(mtd, chip);
+}
+
+static int
+toshiba_nand_read_subpage_benand(struct mtd_info *mtd,
+				 struct nand_chip *chip, uint32_t data_offs,
+				 uint32_t readlen, uint8_t *bufpoi, int page)
+{
+	int ret;
+
+	ret = nand_read_page_op(chip, page, data_offs,
+				bufpoi + data_offs, readlen);
+	if (ret)
+		return ret;
+
+	return toshiba_nand_benand_eccstatus(mtd, chip);
+}
+
+static void toshiba_nand_benand_init(struct nand_chip *chip)
+{
+	struct mtd_info *mtd = nand_to_mtd(chip);
+
+	/*
+	 * On BENAND, the entire OOB region can be used by the MTD user.
+	 * The calculated ECC bytes are stored into other isolated
+	 * area which is not accessible to users.
+	 * This is why chip->ecc.bytes = 0.
+	 */
+	chip->ecc.bytes = 0;
+	chip->ecc.size = 512;
+	chip->ecc.strength = 8;
+	chip->ecc.read_page = toshiba_nand_read_page_benand;
+	chip->ecc.read_subpage = toshiba_nand_read_subpage_benand;
+	chip->ecc.write_page = nand_write_page_raw;
+	chip->ecc.read_page_raw = nand_read_page_raw;
+	chip->ecc.write_page_raw = nand_write_page_raw;
+
+	chip->options |= NAND_SUBPAGE_READ;
+
+	mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
+}
+
 static void toshiba_nand_decode_id(struct nand_chip *chip)
 {
 	struct mtd_info *mtd = nand_to_mtd(chip);
@@ -68,6 +148,10 @@ static int toshiba_nand_init(struct nand_chip *chip)
 	if (nand_is_slc(chip))
 		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
 
+	if (nand_is_slc(chip) && (chip->id.data[4] & 0x80) /* BENAND */ &&
+	    (chip->ecc.mode == NAND_ECC_ON_DIE))
+		toshiba_nand_benand_init(chip);
+
 	return 0;
 }
 
-- 
2.7.4

Re: [PATCH v5] mtd: nand: toshiba: Add support for Toshiba Memory BENAND (Built-in ECC NAND)

[Boris Brezillon]

On Thu, 19 Jul 2018 16:53:33 +0900
KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp> wrote:

> From: yoshitake.kobayashi@toshiba.co.jp
> 
> This patch is a patch to support TOSHIBA MEMORY CORPORATION BENAND
> memory devices.  Check the status of the built-in ECC with the Read
> Status command without using the vendor specific command.  The Read
> Status command only knows whether there was bitflips above the
> threshold and can not get accurate bitflips.  For now, I set
> max_bitflips mtd->bitflip_threshold.
> 
> Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
> ---
>  drivers/mtd/nand/raw/nand_toshiba.c | 84 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 84 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/nand_toshiba.c b/drivers/mtd/nand/raw/nand_toshiba.c
> index ab43f02..6cec923 100644
> --- a/drivers/mtd/nand/raw/nand_toshiba.c
> +++ b/drivers/mtd/nand/raw/nand_toshiba.c
> @@ -17,6 +17,86 @@
>  
>  #include <linux/mtd/rawnand.h>
>  
> +/* Recommended to rewrite for BENAND */
> +#define TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED	BIT(3)
> +
> +static int toshiba_nand_benand_eccstatus(struct mtd_info *mtd,
> +					 struct nand_chip *chip)
> +{
> +	int ret;
> +	unsigned int max_bitflips = 0;
> +	u8 status;
> +
> +	/* Check Status */
> +	ret = nand_status_op(chip, &status);
> +	if (ret)
> +		return ret;
> +
> +	if (status & NAND_STATUS_FAIL) {
> +		/* uncorrected */
> +		mtd->ecc_stats.failed++;
> +	} else if (status & TOSHIBA_NAND_STATUS_REWRITE_RECOMMENDED) {
> +		/* corrected */
> +		max_bitflips = mtd->bitflip_threshold;
> +		mtd->ecc_stats.corrected += max_bitflips;
> +	}
> +
> +	return max_bitflips;
> +}
> +
> +static int
> +toshiba_nand_read_page_benand(struct mtd_info *mtd,
> +			      struct nand_chip *chip, uint8_t *buf,
> +			      int oob_required, int page)
> +{
> +	int ret;
> +
> +	ret = nand_read_page_raw(mtd, chip, buf, oob_required, page);
> +	if (ret)
> +		return ret;
> +
> +	return toshiba_nand_benand_eccstatus(mtd, chip);
> +}
> +
> +static int
> +toshiba_nand_read_subpage_benand(struct mtd_info *mtd,
> +				 struct nand_chip *chip, uint32_t data_offs,
> +				 uint32_t readlen, uint8_t *bufpoi, int page)
> +{
> +	int ret;
> +
> +	ret = nand_read_page_op(chip, page, data_offs,
> +				bufpoi + data_offs, readlen);
> +	if (ret)
> +		return ret;
> +
> +	return toshiba_nand_benand_eccstatus(mtd, chip);
> +}
> +
> +static void toshiba_nand_benand_init(struct nand_chip *chip)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +
> +	/*
> +	 * On BENAND, the entire OOB region can be used by the MTD user.
> +	 * The calculated ECC bytes are stored into other isolated
> +	 * area which is not accessible to users.
> +	 * This is why chip->ecc.bytes = 0.
> +	 */
> +	chip->ecc.bytes = 0;
> +	chip->ecc.size = 512;
> +	chip->ecc.strength = 8;
> +	chip->ecc.read_page = toshiba_nand_read_page_benand;
> +	chip->ecc.read_subpage = toshiba_nand_read_subpage_benand;
> +	chip->ecc.write_page = nand_write_page_raw;
> +	chip->ecc.read_page_raw = nand_read_page_raw;
> +	chip->ecc.write_page_raw = nand_write_page_raw;

Well, in this case raw accesses are not supported since you can't
disabled ECC. I just introduced nand_{read,write}_page_raw_notsupp(),
so you should probably use them.

> +
> +	chip->options |= NAND_SUBPAGE_READ;
> +
> +	mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
> +}
> +
>  static void toshiba_nand_decode_id(struct nand_chip *chip)
>  {
>  	struct mtd_info *mtd = nand_to_mtd(chip);
> @@ -68,6 +148,10 @@ static int toshiba_nand_init(struct nand_chip *chip)
>  	if (nand_is_slc(chip))
>  		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
>  
> +	if (nand_is_slc(chip) && (chip->id.data[4] & 0x80) /* BENAND */ &&

Please put the /* BENAND */ comment above the if () block.
Maybe you should have a macro for the 0x80 value

#define TOSHIBA_NAND_ID4_IS_BENAND		BIT(7)

and then test

	chip->id.data[4] & TOSHIBA_NAND_ID4_IS_BENAND

> +	    (chip->ecc.mode == NAND_ECC_ON_DIE))

Unneeded parens around chip->ecc.mode == NAND_ECC_ON_DIE and
chip->id.data[4] & 0x80 tests.

> +		toshiba_nand_benand_init(chip);
> +
>  	return 0;
>  }
>