[PATCH 2/2] mtd: spi-nor-core: add 4-byte OPCODE support for Winbond W25Q256JV

[Robert Marko]

Winbond W25Q256FV and W25Q256JV share the same JEDEC ID, but only
W25Q256JV fully supports 4-byte OPCODE-s.

In order to differentiate between them we can use the SFDP header version
and apply a fixup post BFPT.

Based on upstream Linux commit ("mtd: spi-nor: winbond: Fix 4-byte opcode
support for w25q256").

Signed-off-by: Robert Marko <robert.ma...@sartura.hr>
---
 drivers/mtd/spi/spi-nor-core.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 7615ba602f..8882b045ce 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -3816,6 +3816,32 @@ static struct spi_nor_fixups macronix_octal_fixups = {
 };
 #endif /* CONFIG_SPI_FLASH_MACRONIX */
 
+#if CONFIG_IS_ENABLED(SPI_FLASH_WINBOND)
+static int w25q256_post_bfpt_fixup(struct spi_nor *nor,
+                                  const struct sfdp_parameter_header *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(header->major == SFDP_JESD216_MAJOR &&
+          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_fixup,
+};
+#endif /* CONFIG_SPI_FLASH_WINBOND */
+
 /** spi_nor_octal_dtr_enable() - enable Octal DTR I/O if needed
  * @nor:                 pointer to a 'struct spi_nor'
  *
@@ -4004,6 +4030,11 @@ void spi_nor_set_fixups(struct spi_nor *nor)
 #if CONFIG_IS_ENABLED(SPI_FLASH_MACRONIX)
        nor->fixups = &macronix_octal_fixups;
 #endif /* SPI_FLASH_MACRONIX */
+
+#if CONFIG_IS_ENABLED(SPI_FLASH_WINBOND)
+       if (!strcmp(nor->info->name, "w25q256"))
+               nor->fixups = &w25q256_fixups;
+#endif /* SPI_FLASH_WINBOND */
 }
 
 int spi_nor_scan(struct spi_nor *nor)
-- 
2.44.0