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Subject[PATCH -next v3 1/2] mtd: nand: toshiba: Retrieve ECC requirements from extended ID
Date
This patch enables support to read the ECC strength and size from the
NAND flash using Toshiba Memory SLC NAND extended-ID. This patch is
based on the information of the 6th ID byte of the Toshiba Memory SLC
NAND.

Signed-off-by: KOBAYASHI Yoshitake <yoshitake.kobayashi@toshiba.co.jp>
---
drivers/mtd/nand/nand_toshiba.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
index 57df857..c2c141b 100644
--- a/drivers/mtd/nand/nand_toshiba.c
+++ b/drivers/mtd/nand/nand_toshiba.c
@@ -35,6 +35,34 @@ static void toshiba_nand_decode_id(struct nand_chip *chip)
(chip->id.data[5] & 0x7) == 0x6 /* 24nm */ &&
!(chip->id.data[4] & 0x80) /* !BENAND */)
mtd->oobsize = 32 * mtd->writesize >> 9;
+
+ /*
+ * Extract ECC requirements from 6th id byte.
+ * For Toshiba SLC, ecc requrements are as follows:
+ * - 43nm: 1 bit ECC for each 512Byte is required.
+ * - 32nm: 4 bit ECC for each 512Byte is required.
+ * - 24nm: 8 bit ECC for each 512Byte is required.
+ */
+ if (chip->id.len >= 6 && nand_is_slc(chip)) {
+ chip->ecc_step_ds = 512;
+ switch (chip->id.data[5] & 0x7) {
+ case 0x4:
+ chip->ecc_strength_ds = 1;
+ break;
+ case 0x5:
+ chip->ecc_strength_ds = 4;
+ break;
+ case 0x6:
+ chip->ecc_strength_ds = 8;
+ break;
+ default:
+ WARN(1, "Could not get ECC info");
+ chip->ecc_step_ds = 0;
+ break;
+ }
+ } else if (chip->id.len < 6 && nand_is_slc(chip)) {
+ WARN(1, "Could not get ECC info, 6th nand id byte does not exist.");
+ }
}

static int toshiba_nand_init(struct nand_chip *chip)
--
2.7.4

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