mtd: nand: toshiba: Retrieve ECC requirements from extended ID

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>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

diff --git a/drivers/mtd/nand/nand_toshiba.c b/drivers/mtd/nand/nand_toshiba.c
index 57df857..ab43f02 100644 (file)
--- a/drivers/mtd/nand/nand_toshiba.c
+++ b/drivers/mtd/nand/nand_toshiba.c
@@ -35,6 +35,32 @@ 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;
+               }
+       }
 }
 
 static int toshiba_nand_init(struct nand_chip *chip)