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Subject[PATCH] mtd: nand: Add support for reading ooblayout from device tree
Date
By specifying the properties "mtd-oob-ecc" and "mtd-oob-free", it is
now possible to specify from devicetree where the ECC data is located
inside the OOB region.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
Documentation/devicetree/bindings/mtd/nand.txt | 7 +++++
drivers/mtd/nand/raw/nand_base.c | 42 ++++++++++++++++++++++++++
2 files changed, 49 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/nand.txt b/Documentation/devicetree/bindings/mtd/nand.txt
index 8bb11d809429..118ea92787cb 100644
--- a/Documentation/devicetree/bindings/mtd/nand.txt
+++ b/Documentation/devicetree/bindings/mtd/nand.txt
@@ -45,6 +45,13 @@ Optional NAND chip properties:
as reliable as possible.
- nand-rb: shall contain the native Ready/Busy ids.

+- nand-oob-ecc: <offset, length> couples of integers, specifying the offset
+ and length of the ECC data in the OOB region. There can be more
+ than one couple.
+- nand-oob-free: <offset, length> couples of integers, specifying the offset
+ and length of a free-to-use area in the OOB region. There can be
+ more than one couple.
+
The ECC strength and ECC step size properties define the correction capability
of a controller. Together, they say a controller can correct "{strength} bit
errors per {size} bytes".
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index 72f3a89da513..c905531effb0 100644
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -213,6 +213,43 @@ static const struct mtd_ooblayout_ops nand_ooblayout_lp_hamming_ops = {
.free = nand_ooblayout_free_lp_hamming,
};

+static int nand_oob_of(struct device_node *np, int section,
+ struct mtd_oob_region *oobregion, const char *prop)
+{
+ int ret = of_property_read_u32_index(np, prop,
+ section * 2, &oobregion->offset);
+ if (ret == -EOVERFLOW)
+ return -ERANGE; /* We're done */
+ if (ret)
+ return ret;
+
+ ret = of_property_read_u32_index(np, prop,
+ section * 2 + 1, &oobregion->length);
+ if (ret == -EOVERFLOW)
+ return -EINVAL; /* We must have an even number of integers */
+
+ return ret;
+}
+
+static int nand_ooblayout_ecc_of(struct mtd_info *mtd, int section,
+ struct mtd_oob_region *oobregion)
+{
+ return nand_oob_of(mtd->dev.of_node, section,
+ oobregion, "nand-oob-ecc");
+}
+
+static int nand_ooblayout_free_of(struct mtd_info *mtd, int section,
+ struct mtd_oob_region *oobregion)
+{
+ return nand_oob_of(mtd->dev.of_node, section,
+ oobregion, "nand-oob-free");
+}
+
+static const struct mtd_ooblayout_ops nand_ooblayout_of_ops = {
+ .ecc = nand_ooblayout_ecc_of,
+ .free = nand_ooblayout_free_of,
+};
+
static int check_offs_len(struct mtd_info *mtd,
loff_t ofs, uint64_t len)
{
@@ -5843,6 +5880,11 @@ static int nand_dt_init(struct nand_chip *chip)
if (of_property_read_bool(dn, "nand-ecc-maximize"))
chip->ecc.options |= NAND_ECC_MAXIMIZE;

+ if (!chip->mtd.ooblayout &&
+ of_property_read_bool(dn, "nand-oob-ecc") &&
+ of_property_read_bool(dn, "nand-oob-free"))
+ chip->mtd.ooblayout = &nand_ooblayout_of_ops;
+
return 0;
}

--
2.11.0
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