mtd: nand: add ooblayout for old hamming layout

commit 6a623e07694437ad09f382a13f76cffc32239a7f upstream.

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")
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 69 insertions, 1 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 3bde96a3f7bf..f222f8a7ba52 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -138,6 +138,74 @@ 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)
 {
@@ -4565,7 +4633,7 @@ 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",