[PATCH v10 4/6] mtd: spi-nor: sfdp: Get the 8D-8D-8D byte order from BFPT

[AlvinZhou]

From: AlvinZhou <alvinzhou at mxic.com.tw>

From: Tudor Ambarus <tudor.ambarus at linaro.org>

Parse BFPT in order to retrieve the byte order in 8D-8D-8D mode.

This info flag will be used as a basis to determine whether
there is byte swapping of data for SPI NOR flash in octal
DTR mode.

The controller driver will check whether byte swapping is supported
to determine whether the corresponding operation are supported,
thus avoiding the generation of unexpected data order.

Merge Tudor's patch and add modifications for suiting newer version
of Linux kernel.

Reviewed-by: Michael Walle <mwalle at kernel.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus at linaro.org>
Signed-off-by: JaimeLiao <jaimeliao at mxic.com.tw>
Signed-off-by: AlvinZhou <alvinzhou at mxic.com.tw>
---
 drivers/mtd/spi-nor/sfdp.c | 4 ++++
 drivers/mtd/spi-nor/sfdp.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index 5b1117265bd2..21727f9a4ac6 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -671,6 +671,10 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
 		return -EOPNOTSUPP;
 	}
 
+	/* Byte order in 8D-8D-8D mode */
+	if (bfpt.dwords[SFDP_DWORD(18)] & BFPT_DWORD18_BYTE_ORDER_SWAPPED)
+		nor->flags |= SNOR_F_SWAP16;
+
 	return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt);
 }
 
diff --git a/drivers/mtd/spi-nor/sfdp.h b/drivers/mtd/spi-nor/sfdp.h
index da0fe5aa9bb0..d90cbd7331f7 100644
--- a/drivers/mtd/spi-nor/sfdp.h
+++ b/drivers/mtd/spi-nor/sfdp.h
@@ -130,6 +130,7 @@ struct sfdp_bfpt {
 #define BFPT_DWORD18_CMD_EXT_INV		(0x1UL << 29) /* Invert */
 #define BFPT_DWORD18_CMD_EXT_RES		(0x2UL << 29) /* Reserved */
 #define BFPT_DWORD18_CMD_EXT_16B		(0x3UL << 29) /* 16-bit opcode */
+#define BFPT_DWORD18_BYTE_ORDER_SWAPPED		BIT(31)	/* Byte sawp of 16-bit in 8D-8D-8D mode */
 
 struct sfdp_parameter_header {
 	u8		id_lsb;
-- 
2.25.1