Subject: [PATCH] mtd: spi-nor: fix 4-byte opcode support for w25q256
From: Mantas Pucka <[email-masked]>
To: [email-masked]
Date: Wed, 15 Apr 2020 16:48:30 +0300

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.

for OpenWRT only: rebased to linux-v5.4

Signed-off-by: Mantas Pucka <[email-masked]>
---

--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -2172,6 +2172,32 @@ static struct spi_nor_fixups gd25q256_fi
 	.default_init = gd25q256_default_init,
 };
 
+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,
+};
+
 /* NOTE: double check command sets and memory organization when you add
  * more nor chips.  This current list focusses on newer chips, which
  * have been converging on command sets which including JEDEC ID.
@@ -2515,7 +2541,8 @@ static const struct flash_info spi_nor_i
 	{ "w25q80", INFO(0xef5014, 0, 64 * 1024,  16, SECT_4K) },
 	{ "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) },
+	{ "w25q256", INFO(0xef4019, 0, 64 * 1024, 512, 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) },
 	{ "w25m512jv", INFO(0xef7119, 0, 64 * 1024, 1024,