mtd: rawnand: denali_dt: Add support for configuring SPARE_AREA_SKIP_…

…BYTES

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@denx.de>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
To: linux-mtd@lists.infradead.org
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

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);

drivers/mtd/nand/raw/denali_dt.c

@@ -27,13 +27,15 @@ 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;
 };
 
 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,
 };
 
@@ -123,6 +127,7 @@ static int denali_dt_probe(struct platform_device *pdev)
 
 	denali->revision = data->revision;
 	denali->caps = data->caps;
+	denali->oob_skip_bytes = data->oob_skip_bytes;
 	denali->ecc_caps = data->ecc_caps;
 
 	denali->dev = dev;