[PATCH v2 2/2] mtd: rawnand: ESMT: retrieve ECC requirements from 5th id byte

[Marcel Ziswiler]

From: Marcel Ziswiler <marcel.ziswiler@xxxxxxxxxxx>

This patch enables support to read the ECC level from the NAND flash
using ESMT SLC NAND ID byte 5 information as documented e.g. in the
following data sheet:

https://www.esmt.com.tw/upload/pdf/ESMT/datasheets/F59L1G81LA(2Y).pdf

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@xxxxxxxxxxx>

---

Changes in v2:
- Also hook the new esmt_nand_manuf_ops to the ESMT entry in the
  nand_manufacturer table as discovered by Boris.
- Also add the Makefile as well as include file changes as required.

 drivers/mtd/nand/raw/Makefile    |  1 +
 drivers/mtd/nand/raw/nand_esmt.c | 46 ++++++++++++++++++++++++++++++++++++++++
 drivers/mtd/nand/raw/nand_ids.c  |  2 +-
 include/linux/mtd/rawnand.h      |  1 +
 4 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 drivers/mtd/nand/raw/nand_esmt.c

diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
index d5a5f9832b88..ecb4d6cde1ee 100644
--- a/drivers/mtd/nand/raw/Makefile
+++ b/drivers/mtd/nand/raw/Makefile
@@ -60,6 +60,7 @@ obj-$(CONFIG_MTD_NAND_TEGRA)		+= tegra_nand.o
 
 nand-objs := nand_base.o nand_bbt.o nand_timings.o nand_ids.o
 nand-objs += nand_amd.o
+nand-objs += nand_esmt.o
 nand-objs += nand_hynix.o
 nand-objs += nand_macronix.o
 nand-objs += nand_micron.o
diff --git a/drivers/mtd/nand/raw/nand_esmt.c b/drivers/mtd/nand/raw/nand_esmt.c
new file mode 100644
index 000000000000..360d351ac043
--- /dev/null
+++ b/drivers/mtd/nand/raw/nand_esmt.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Toradex AG
+ *
+ * Author: Marcel Ziswiler <marcel.ziswiler@xxxxxxxxxxx>
+ */
+
+#include <linux/mtd/rawnand.h>
+
+static void esmt_nand_decode_id(struct nand_chip *chip)
+{
+	nand_decode_ext_id(chip);
+
+	/* Extract ECC requirements from 5th id byte. */
+	if (chip->id.len >= 5 && nand_is_slc(chip)) {
+		chip->ecc_step_ds = 512;
+		switch (chip->id.data[4] & 0x3) {
+		case 0x0:
+			chip->ecc_strength_ds = 4;
+			break;
+		case 0x1:
+			chip->ecc_strength_ds = 2;
+			break;
+		case 0x2:
+			chip->ecc_strength_ds = 1;
+			break;
+		default:
+			WARN(1, "Could not get ECC info");
+			chip->ecc_step_ds = 0;
+			break;
+		}
+	}
+}
+
+static int esmt_nand_init(struct nand_chip *chip)
+{
+	if (nand_is_slc(chip))
+		chip->bbt_options |= NAND_BBT_SCAN2NDPAGE;
+
+	return 0;
+}
+
+const struct nand_manufacturer_ops esmt_nand_manuf_ops = {
+	.detect = esmt_nand_decode_id,
+	.init = esmt_nand_init,
+};
diff --git a/drivers/mtd/nand/raw/nand_ids.c b/drivers/mtd/nand/raw/nand_ids.c
index 0851cd86bf19..f904f8b987e3 100644
--- a/drivers/mtd/nand/raw/nand_ids.c
+++ b/drivers/mtd/nand/raw/nand_ids.c
@@ -172,7 +172,7 @@ static const struct nand_manufacturer nand_manufacturers[] = {
 	{NAND_MFR_AMD, "AMD/Spansion", &amd_nand_manuf_ops},
 	{NAND_MFR_ATO, "ATO"},
 	{NAND_MFR_EON, "Eon"},
-	{NAND_MFR_ESMT, "ESMT"},
+	{NAND_MFR_ESMT, "ESMT", &esmt_nand_manuf_ops},
 	{NAND_MFR_FUJITSU, "Fujitsu"},
 	{NAND_MFR_HYNIX, "Hynix", &hynix_nand_manuf_ops},
 	{NAND_MFR_INTEL, "Intel"},
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
index 20516fc28b74..c4656e3eeba1 100644
--- a/include/linux/mtd/rawnand.h
+++ b/include/linux/mtd/rawnand.h
@@ -1542,6 +1542,7 @@ nand_manufacturer_name(const struct nand_manufacturer *manufacturer)
 extern struct nand_flash_dev nand_flash_ids[];
 
 extern const struct nand_manufacturer_ops amd_nand_manuf_ops;
+extern const struct nand_manufacturer_ops esmt_nand_manuf_ops;
 extern const struct nand_manufacturer_ops hynix_nand_manuf_ops;
 extern const struct nand_manufacturer_ops macronix_nand_manuf_ops;
 extern const struct nand_manufacturer_ops micron_nand_manuf_ops;
-- 
2.14.4