mtd: nand: add ooblayout for old hamming layout

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=6a623e07694437ad09f382a13f76cffc32239a7f
Commit:     6a623e07694437ad09f382a13f76cffc32239a7f
Parent:     b98e1995e4fa9030474a61ed0dbc033464fe5ea0
Author:     Alexander Couzens <lynxis at fe80.eu>
AuthorDate: Tue May 2 12:19:00 2017 +0200
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Tue May 2 18:56:39 2017 -0700

    mtd: nand: add ooblayout for old hamming layout
    
    The old 1-bit hamming layout requires ECC data to be placed at a
    fixed offset, and not necessarily at the end of the OOB area.
    Add this old layout back in order to fix legacy setups.
    
    Fixes: 41b207a70d3a ("mtd: nand: implement the default mtd_ooblayout_ops")
    Cc: <stable at vger.kernel.org>
    Signed-off-by: Alexander Couzens <lynxis at fe80.eu>
    Acked-by: Boris Brezillon <boris.brezillon at free-electrons.com>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/nand/nand_base.c | 70 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 69 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index ed49a1d..d474378 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -139,6 +139,74 @@ const struct mtd_ooblayout_ops nand_ooblayout_lp_ops = {
 };
 EXPORT_SYMBOL_GPL(nand_ooblayout_lp_ops);
 
+/*
+ * Support the old "large page" layout used for 1-bit Hamming ECC where ECC
+ * are placed at a fixed offset.
+ */
+static int nand_ooblayout_ecc_lp_hamming(struct mtd_info *mtd, int section,
+					 struct mtd_oob_region *oobregion)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+
+	if (section)
+		return -ERANGE;
+
+	switch (mtd->oobsize) {
+	case 64:
+		oobregion->offset = 40;
+		break;
+	case 128:
+		oobregion->offset = 80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	oobregion->length = ecc->total;
+	if (oobregion->offset + oobregion->length > mtd->oobsize)
+		return -ERANGE;
+
+	return 0;
+}
+
+static int nand_ooblayout_free_lp_hamming(struct mtd_info *mtd, int section,
+					  struct mtd_oob_region *oobregion)
+{
+	struct nand_chip *chip = mtd_to_nand(mtd);
+	struct nand_ecc_ctrl *ecc = &chip->ecc;
+	int ecc_offset = 0;
+
+	if (section < 0 || section > 1)
+		return -ERANGE;
+
+	switch (mtd->oobsize) {
+	case 64:
+		ecc_offset = 40;
+		break;
+	case 128:
+		ecc_offset = 80;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (section == 0) {
+		oobregion->offset = 2;
+		oobregion->length = ecc_offset - 2;
+	} else {
+		oobregion->offset = ecc_offset + ecc->total;
+		oobregion->length = mtd->oobsize - oobregion->offset;
+	}
+
+	return 0;
+}
+
+const struct mtd_ooblayout_ops nand_ooblayout_lp_hamming_ops = {
+	.ecc = nand_ooblayout_ecc_lp_hamming,
+	.free = nand_ooblayout_free_lp_hamming,
+};
+
 static int check_offs_len(struct mtd_info *mtd,
 					loff_t ofs, uint64_t len)
 {
@@ -4559,7 +4627,7 @@ int nand_scan_tail(struct mtd_info *mtd)
 			break;
 		case 64:
 		case 128:
-			mtd_set_ooblayout(mtd, &nand_ooblayout_lp_ops);
+			mtd_set_ooblayout(mtd, &nand_ooblayout_lp_hamming_ops);
 			break;
 		default:
 			WARN(1, "No oob scheme defined for oobsize %d\n",