Now that the core NAND subsystem has support for on-die ECC, this commit brings the necessary code to support on-die ECC on Micron NANDs. In micron_nand_init(), if the Device Tree indicates an on-die ECC mode, we verify if the NAND chip actually has ECC support and if so, fill in the appropriate fields of nand_chip->ecc and defines the OOB layout according to the NAND datasheet. We then provide an implementation of the ->read_page(), ->read_page_raw(), ->write_page() and ->write_page_raw() operation to properly handle the on-die ECC. In the non-raw functions, we need to enable the internal ECC engine before issuing the NAND_CMD_READ0 or NAND_CMD_SEQIN commands, which is why we set the NAND_ECC_CUSTOM_PAGE_ACCESS option at initialization time (it asks the NAND core to let the NAND driver issue those commands). Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> --- drivers/mtd/nand/nand_micron.c | 147 +++++++++++++++++++++++++++++++++++++++++ include/linux/mtd/nand.h | 2 + 2 files changed, 149 insertions(+) diff --git a/drivers/mtd/nand/nand_micron.c b/drivers/mtd/nand/nand_micron.c index 8770110..e9a445d 100644 --- a/drivers/mtd/nand/nand_micron.c +++ b/drivers/mtd/nand/nand_micron.c @@ -17,6 +17,18 @@ #include <linux/mtd/nand.h> +/* + * Special Micron status bit that indicates when the block has been + * corrected by on-die ECC and should be rewritten + */ +#define NAND_STATUS_WRITE_RECOMMENDED BIT(3) + +/* + * READ ID bit that indicates if the NAND has on-die ECC support, + * located in byte 4. + */ +#define NAND_MICRON_ON_DIE_ECC_CAPABLE BIT(7) + struct nand_onfi_vendor_micron { u8 two_plane_read; u8 read_cache; @@ -66,6 +78,121 @@ static int micron_nand_onfi_init(struct nand_chip *chip) return 0; } +static int micron_nand_on_die_ooblayout_ecc(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + if (section >= 4) + return -ERANGE; + + oobregion->offset = (section * 16) + 8; + oobregion->length = 8; + + return 0; +} + +static int micron_nand_on_die_ooblayout_free(struct mtd_info *mtd, int section, + struct mtd_oob_region *oobregion) +{ + if (section >= 4) + return -ERANGE; + + oobregion->offset = (section * 16) + 2; + oobregion->length = 6; + + return 0; +} + +static const struct mtd_ooblayout_ops micron_nand_on_die_ooblayout_ops = { + .ecc = micron_nand_on_die_ooblayout_ecc, + .free = micron_nand_on_die_ooblayout_free, +}; + +static void micron_nand_on_die_ecc_setup(struct nand_chip *chip, bool enable) +{ + u8 feature[ONFI_SUBFEATURE_PARAM_LEN] = { 0, }; + + if (enable) + feature[0] |= ONFI_FEATURE_ON_DIE_ECC_EN; + + chip->onfi_set_features(nand_to_mtd(chip), chip, + ONFI_FEATURE_ON_DIE_ECC, feature); +} + +static int +micron_nand_read_page_on_die_ecc(struct mtd_info *mtd, struct nand_chip *chip, + uint8_t *buf, int oob_required, + int page) +{ + int status; + int max_bitflips = 0; + + micron_nand_on_die_ecc_setup(chip, true); + + chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page); + chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1); + status = chip->read_byte(mtd); + if (status & NAND_STATUS_FAIL) + mtd->ecc_stats.failed++; + /* + * The internal ECC doesn't tell us the number of bitflips + * that have been corrected, but tells us if it recommends to + * rewrite the block. If it's the case, then we pretend we had + * a number of bitflips equal to the ECC strength, which will + * hint the NAND core to rewrite the block. + */ + else if (status & NAND_STATUS_WRITE_RECOMMENDED) + max_bitflips = chip->ecc.strength; + + chip->cmdfunc(mtd, NAND_CMD_READ0, -1, -1); + + nand_read_page_raw(mtd, chip, buf, oob_required, page); + + micron_nand_on_die_ecc_setup(chip, false); + + return max_bitflips; +} + +static int +micron_nand_write_page_on_die_ecc(struct mtd_info *mtd, struct nand_chip *chip, + const uint8_t *buf, int oob_required, + int page) +{ + micron_nand_on_die_ecc_setup(chip, true); + + chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page); + nand_write_page_raw(mtd, chip, buf, oob_required, page); + chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1); + + micron_nand_on_die_ecc_setup(chip, false); + + return 0; +} + +static int +micron_nand_read_page_raw_on_die_ecc(struct mtd_info *mtd, + struct nand_chip *chip, + uint8_t *buf, int oob_required, + int page) +{ + chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page); + nand_read_page_raw(mtd, chip, buf, oob_required, page); + + return 0; +} + +static int +micron_nand_write_page_raw_on_die_ecc(struct mtd_info *mtd, + struct nand_chip *chip, + const uint8_t *buf, int oob_required, + int page) +{ + chip->cmdfunc(mtd, NAND_CMD_SEQIN, 0x00, page); + nand_write_page_raw(mtd, chip, buf, oob_required, page); + chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1); + + return 0; +} + static int micron_nand_init(struct nand_chip *chip) { struct mtd_info *mtd = nand_to_mtd(chip); @@ -78,6 +205,26 @@ static int micron_nand_init(struct nand_chip *chip) if (mtd->writesize == 2048) chip->bbt_options |= NAND_BBT_SCAN2NDPAGE; + if (chip->ecc.mode == NAND_ECC_ON_DIE) { + if ((chip->id.data[4] & NAND_MICRON_ON_DIE_ECC_CAPABLE) == 0) { + pr_err("On-die ECC selected but not supported\n"); + return -EINVAL; + } + + chip->ecc.options = NAND_ECC_CUSTOM_PAGE_ACCESS; + chip->ecc.bytes = 32; + chip->ecc.strength = 4; + chip->ecc.algo = NAND_ECC_BCH; + chip->ecc.read_page = micron_nand_read_page_on_die_ecc; + chip->ecc.write_page = micron_nand_write_page_on_die_ecc; + chip->ecc.read_page_raw = + micron_nand_read_page_raw_on_die_ecc; + chip->ecc.write_page_raw = + micron_nand_write_page_raw_on_die_ecc; + + mtd_set_ooblayout(mtd, µn_nand_on_die_ooblayout_ops); + } + return 0; } diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index 5fc705d..3320ffd 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -258,6 +258,8 @@ struct nand_chip; /* Vendor-specific feature address (Micron) */ #define ONFI_FEATURE_ADDR_READ_RETRY 0x89 +#define ONFI_FEATURE_ON_DIE_ECC 0x90 +#define ONFI_FEATURE_ON_DIE_ECC_EN BIT(3) /* ONFI subfeature parameters length */ #define ONFI_SUBFEATURE_PARAM_LEN 4 -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html