mtd: nand: spansion S30MLxxxP support

Some Spansion chips have a method for determining eraseblock size that
is incompatible with similar ID chips of other sizes. This implements
some heuristic detection of these differences.

This patch checks for a 5-byte ID with trailing zeros as well as a
512-byte page size to ensure that chips are not misdetected as the
S30MLxxxP ORNAND series.

[Tweaked by Artem a bit]
Signed-off-by: Brian Norris <norris@broadcom.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/nand_base.c

@@ -2900,6 +2900,19 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 		mtd->writesize = type->pagesize;
 		mtd->oobsize = mtd->writesize / 32;
 		busw = type->options & NAND_BUSWIDTH_16;
+
+		/*
+		 * Check for Spansion/AMD ID + repeating 5th, 6th byte since
+		 * some Spansion chips have erasesize that conflicts with size
+		 * listed in nand_ids table
+		 * Data sheet (5 byte ID): Spansion S30ML-P ORNAND (p.39)
+		 */
+		if (*maf_id == NAND_MFR_AMD && id_data[4] != 0x00 &&
+				id_data[5] == 0x00 && id_data[6] == 0x00 &&
+				id_data[7] == 0x00 && mtd->writesize == 512) {
+			mtd->erasesize = 128 * 1024;
+			mtd->erasesize <<= ((id_data[3] & 0x03) << 1);
+		}
 	}
 
 	/* Try to identify manufacturer */