In order to make the ecclayout definition completely dynamic we need to
rework the way the OOB layout are defined and iterated.

Create a few mtd_ooblayout_xxx() helpers to ease OOB bytes manipulation
and hide ecclayout internals to their users.

Signed-off-by: Boris Brezillon <redacted>
---
 drivers/mtd/mtdcore.c   | 401 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mtd/mtd.h |  33 ++++
 2 files changed, 434 insertions(+)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 3096251..14e46ca 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c

@@ -997,6 +997,407 @@ int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 }
 EXPORT_SYMBOL_GPL(mtd_read_oob);
 
+/**
+ * mtd_ooblayout_ecc - Get the OOB region definition of a specific ECC section
+ * @mtd: MTD device structure
+ * @section: ECC section. Depending on the layout you may have all the ECC
+ *	     bytes stored in a single contiguous section, or one section
+ *	     per ECC chunk (and sometime several sections for a single ECC
+ *	     ECC chunk)
+ * @oobecc: OOB region struct filled with the appropriate ECC position
+ *	    information
+ *
+ * This functions return ECC section information in the OOB area. I you want
+ * to get all the ECC bytes information, then you should call
+ * mtd_ooblayout_ecc(mtd, section++, oobecc) until it returns -ERANGE.
+ *
+ * Returns zero on success, a negative error code otherwise.
+ */
+int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,
+		      struct mtd_oob_region *oobecc)
+{
+	int eccbyte = 0, cursection = 0, length = 0, eccpos = 0;
+
+	memset(oobecc, 0, sizeof(*oobecc));
+
+	if (!mtd || section < 0)
+		return -EINVAL;
+
+	if (!mtd->ecclayout)
+		return -ENOTSUPP;
+
+	if (mtd->ecclayout->eccbytes < 1)
+		return -ERANGE;
+
+	/*
+	 * This logic allows us to reuse the ->ecclayout information and
+	 * expose them as ECC regions (as done for the OOB free regions).
+	 *
+	 * TODO: this should be dropped as soon as we get rid of the
+	 * ->ecclayout field.
+	 */
+	for (eccbyte = 0; eccbyte < mtd->ecclayout->eccbytes; eccbyte++) {
+		eccpos = mtd->ecclayout->eccpos[eccbyte];
+
+		if (eccbyte < mtd->ecclayout->eccbytes - 1) {
+			int neccpos = mtd->ecclayout->eccpos[eccbyte + 1];
+
+			if (eccpos + 1 == neccpos) {
+				length++;
+				continue;
+			}
+		}
+
+		if (section == cursection)
+			break;
+
+		length = 0;
+		cursection++;
+	}
+
+	if (cursection != section)