[PATCH] mtd: spi-nor: fix 4-byte opcode support for w25q256

[Mantas Pucka <mantas@8devices.com>]

There are 2 different chips (w25q256fv and w25q256jv) that share
the same JEDEC ID. Only w25q256jv fully supports 4-byte opcodes.
Use SFDP header version to differentiate between them.

Signed-off-by: Mantas Pucka <mantas@8devices.com>
---
 drivers/mtd/spi-nor/sfdp.c    |  4 ----
 drivers/mtd/spi-nor/sfdp.h    |  6 ++++++
 drivers/mtd/spi-nor/winbond.c | 30 ++++++++++++++++++++++++++++--
 3 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
index f6038d3..27838f6 100644
--- a/drivers/mtd/spi-nor/sfdp.c
+++ b/drivers/mtd/spi-nor/sfdp.c
@@ -21,10 +21,6 @@
 #define SFDP_4BAIT_ID		0xff84  /* 4-byte Address Instruction Table */
 
 #define SFDP_SIGNATURE		0x50444653U
-#define SFDP_JESD216_MAJOR	1
-#define SFDP_JESD216_MINOR	0
-#define SFDP_JESD216A_MINOR	5
-#define SFDP_JESD216B_MINOR	6
 
 struct sfdp_header {
 	u32		signature; /* Ox50444653U <=> "SFDP" */
diff --git a/drivers/mtd/spi-nor/sfdp.h b/drivers/mtd/spi-nor/sfdp.h
index e0a8ded..b84abd0 100644
--- a/drivers/mtd/spi-nor/sfdp.h
+++ b/drivers/mtd/spi-nor/sfdp.h
@@ -7,6 +7,12 @@
 #ifndef __LINUX_MTD_SFDP_H
 #define __LINUX_MTD_SFDP_H
 
+/* SFDP revisions */
+#define SFDP_JESD216_MAJOR	1
+#define SFDP_JESD216_MINOR	0
+#define SFDP_JESD216A_MINOR	5
+#define SFDP_JESD216B_MINOR	6
+
 /* Basic Flash Parameter Table */
 
 /*
diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
index 17deaba..50b2478 100644
--- a/drivers/mtd/spi-nor/winbond.c
+++ b/drivers/mtd/spi-nor/winbond.c
@@ -8,6 +8,32 @@
 
 #include "core.h"
 
+static int
+w25q256_post_bfpt_fixups(struct spi_nor *nor,
+			 const struct sfdp_parameter_header *bfpt_header,
+			 const struct sfdp_bfpt *bfpt,
+			 struct spi_nor_flash_parameter *params)
+{
+	/*
+	 * W25Q256JV supports 4B opcodes but W25Q256FV does not.
+	 * Unfortunately, Winbond has re-used the same JEDEC ID for both
+	 * variants which prevents us from defining a new entry in the parts
+	 * table.
+	 * To differentiate between W25Q256JV and W25Q256FV check SFDP header
+	 * version: only JV has JESD216A compliant structure (version 5)
+	 */
+
+	if (bfpt_header->major == SFDP_JESD216_MAJOR &&
+	    bfpt_header->minor == SFDP_JESD216A_MINOR)
+		nor->flags |= SNOR_F_4B_OPCODES;
+
+	return 0;
+}
+
+static struct spi_nor_fixups w25q256_fixups = {
+	.post_bfpt = w25q256_post_bfpt_fixups,
+};
+
 static const struct flash_info winbond_parts[] = {
 	/* Winbond -- w25x "blocks" are 64K, "sectors" are 4KiB */
 	{ "w25x05", INFO(0xef3010, 0, 64 * 1024,  1,  SECT_4K) },
@@ -53,8 +79,8 @@ static const struct flash_info winbond_parts[] = {
 	{ "w25q80bl", INFO(0xef4014, 0, 64 * 1024,  16, SECT_4K) },
 	{ "w25q128", INFO(0xef4018, 0, 64 * 1024, 256, SECT_4K) },
 	{ "w25q256", INFO(0xef4019, 0, 64 * 1024, 512,
-			  SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
-			  SPI_NOR_4B_OPCODES) },
+			  SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)
+			  .fixups = &w25q256_fixups },
 	{ "w25q256jvm", INFO(0xef7019, 0, 64 * 1024, 512,
 			     SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
 	{ "w25q256jw", INFO(0xef6019, 0, 64 * 1024, 512,
-- 
2.7.4