mtd: create an mtd_ooblayout_ops struct to ease ECC layout definition

ECC layout definitions are currently exposed using the nand_ecclayout
struct which embeds oobfree and eccpos arrays with predefined size.
This approach was acceptable when NAND chips were providing relatively
small OOB regions, but MLC and TLC now provide OOB regions of several
hundreds of bytes, which implies a non negligible overhead for everybody
even those who only need to support legacy NANDs.

Create an mtd_ooblayout_ops interface providing the same functionality
(expose the ECC and oobfree layout) without the need for this huge
structure.

The mtd->ecclayout is now deprecated and should be replaced by the
equivalent mtd_ooblayout_ops. In the meantime we provide a wrapper around
the ->ecclayout field to ease migration to this new model.

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

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index f53d9d72b23a..1f13e32556f8 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -317,6 +317,27 @@ static int part_block_markbad(struct mtd_info *mtd, loff_t ofs)
 	return res;
 }
 
+static int part_ooblayout_ecc(struct mtd_info *mtd, int section,
+			      struct mtd_oob_region *oobregion)
+{
+	struct mtd_part *part = mtd_to_part(mtd);
+
+	return mtd_ooblayout_ecc(part->master, section, oobregion);
+}
+
+static int part_ooblayout_free(struct mtd_info *mtd, int section,
+			       struct mtd_oob_region *oobregion)
+{
+	struct mtd_part *part = mtd_to_part(mtd);
+
+	return mtd_ooblayout_free(part->master, section, oobregion);
+}
+
+static const struct mtd_ooblayout_ops part_ooblayout_ops = {
+	.ecc = part_ooblayout_ecc,
+	.free = part_ooblayout_free,
+};
+
 static inline void free_partition(struct mtd_part *p)
 {
 	kfree(p->mtd.name);
@@ -533,7 +554,7 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
 			part->name);
 	}
 
-	mtd_set_ecclayout(&slave->mtd, master->ecclayout);
+	mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
 	slave->mtd.ecc_step_size = master->ecc_step_size;
 	slave->mtd.ecc_strength = master->ecc_strength;
 	slave->mtd.bitflip_threshold = master->bitflip_threshold;