[PATCH V2] mtd: rawnand: denali_dt: Add support for configuring SPARE_AREA_SKIP_BYTES

[Marek Vasut <marex@xxxxxxx>]

The SPARE_AREA_SKIP_BYTES register is reset when the controller reset
signal is toggled. Yet, this register must be configured to match the
content of the NAND OOB area. The current default value is always set
to 8 and is programmed into the hardware in case the hardware was not
programmed before (e.g. in a bootloader) with a different value. This
however does not work when the block is reset properly by Linux.

On Altera SoCFPGA CycloneV, ArriaV and Arria10, which are the SoCFPGA
platforms which support booting from NAND, the SPARE_AREA_SKIP_BYTES
value must be set to 2. On Socionext Uniphier, the value is 8. This
patch adds support for preconfiguring the default value and handles
the special SoCFPGA case by setting the default to 2 on all SoCFPGA
platforms, while retaining the original behavior and default value of
8 on all the other platforms.

Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
To: linux-mtd@xxxxxxxxxxxxxxxxxxx
Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
---
V2: Move denali->oob_skip_bytes = data->oob_skip_bytes; right after
    of_device_get_match_data()
---
 drivers/mtd/nand/raw/denali.c    | 13 ++++++++++---
 drivers/mtd/nand/raw/denali_dt.c |  5 +++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/nand/raw/denali.c b/drivers/mtd/nand/raw/denali.c
index 3102ddbd8abdb..b6c463d021677 100644
--- a/drivers/mtd/nand/raw/denali.c
+++ b/drivers/mtd/nand/raw/denali.c
@@ -1302,14 +1302,21 @@ int denali_init(struct denali_controller *denali)
 
 	/*
 	 * Set how many bytes should be skipped before writing data in OOB.
+	 * If a non-zero value has already been configured, update it in HW.
 	 * If a non-zero value has already been set (by firmware or something),
 	 * just use it. Otherwise, set the driver's default.
 	 */
-	denali->oob_skip_bytes = ioread32(denali->reg + SPARE_AREA_SKIP_BYTES);
-	if (!denali->oob_skip_bytes) {
-		denali->oob_skip_bytes = DENALI_DEFAULT_OOB_SKIP_BYTES;
+	if (denali->oob_skip_bytes) {
 		iowrite32(denali->oob_skip_bytes,
 			  denali->reg + SPARE_AREA_SKIP_BYTES);
+	} else {
+		denali->oob_skip_bytes =
+			ioread32(denali->reg + SPARE_AREA_SKIP_BYTES);
+		if (!denali->oob_skip_bytes) {
+			denali->oob_skip_bytes = DENALI_DEFAULT_OOB_SKIP_BYTES;
+			iowrite32(denali->oob_skip_bytes,
+				  denali->reg + SPARE_AREA_SKIP_BYTES);
+		}
 	}
 
 	iowrite32(0, denali->reg + TRANSFER_SPARE_REG);
diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
index 8b779a899dcf4..443f9c1f6854d 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -27,6 +27,7 @@ struct denali_dt {
 struct denali_dt_data {
 	unsigned int revision;
 	unsigned int caps;
+	unsigned int oob_skip_bytes;
 	const struct nand_ecc_caps *ecc_caps;
 };
 
@@ -34,6 +35,7 @@ NAND_ECC_CAPS_SINGLE(denali_socfpga_ecc_caps, denali_calc_ecc_bytes,
 		     512, 8, 15);
 static const struct denali_dt_data denali_socfpga_data = {
 	.caps = DENALI_CAP_HW_ECC_FIXUP,
+	.oob_skip_bytes = 2,
 	.ecc_caps = &denali_socfpga_ecc_caps,
 };
 
@@ -42,6 +44,7 @@ NAND_ECC_CAPS_SINGLE(denali_uniphier_v5a_ecc_caps, denali_calc_ecc_bytes,
 static const struct denali_dt_data denali_uniphier_v5a_data = {
 	.caps = DENALI_CAP_HW_ECC_FIXUP |
 		DENALI_CAP_DMA_64BIT,
+	.oob_skip_bytes = 8,
 	.ecc_caps = &denali_uniphier_v5a_ecc_caps,
 };
 
@@ -51,6 +54,7 @@ static const struct denali_dt_data denali_uniphier_v5b_data = {
 	.revision = 0x0501,
 	.caps = DENALI_CAP_HW_ECC_FIXUP |
 		DENALI_CAP_DMA_64BIT,
+	.oob_skip_bytes = 8,
 	.ecc_caps = &denali_uniphier_v5b_ecc_caps,
 };
 
@@ -122,6 +126,7 @@ static int denali_dt_probe(struct platform_device *pdev)
 		denali->revision = data->revision;
 		denali->caps = data->caps;
 		denali->ecc_caps = data->ecc_caps;
+		denali->oob_skip_bytes = data->oob_skip_bytes;
 	}
 
 	denali->dev = dev;
-- 
2.24.1


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