[PATCH 1/7] mtd: spi-nor: core: Introduce SPI_NOR_PARSE_SFDP

[Tudor Ambarus]

SPI NOR flashes that statically declare one of the
SPI_NOR_{DUAL, QUAD, OCTAL, OCTAL_DTR}_READ flags, and do not support
the RDSFDP command, are gratuiously receiving the RDSFDP command,
in the attempt of parsing the SFDP tables. It is not desirable to issue
comands that are not supported, so introduce a flag to help on this
situation.

New flash additions that support the SFDP standard should be declared
using SPI_NOR_PARSE_SFDP. Support that can be discovered when parsing
SFDP should not be duplicated by explicit flags at flash declaration.
All the flash parameters will be discovered when parsing SFDP.
Sometimes manufacturers wrongly define some fields in the SFDP tables.
If that's the case, SFDP data can be ammended with the fixups() hooks.
It is not common, but if the SFDP tables are entirely wrong, and it
does not worth the hassle to tweak the SFDP parameters by using the
fixups hooks, or if the flash does not define the SFDP tables at all,
then statically init the flash with the SPI_NOR_SKIP_SFDP flag and
specify the reset of flash capabilities with the flash info flags.

With time, we want to convert all flashes to SPI_NOR_PARSE_SFDP and
stop triggering the SFDP parsing with the
SPI_NOR_{DUAL, QUAD, OCTAL*}_READ flags. Getting rid of the
SPI_NOR_{OCTAL, OCTAL_DTR}_READ trigger is easy achievable, the reset
are a long term goal.

Signed-off-by: Tudor Ambarus <tudor.ambarus at microchip.com>
---
 drivers/mtd/spi-nor/core.c | 3 ++-
 drivers/mtd/spi-nor/core.h | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index cc08bd707378..3d9f3698fb7b 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2726,7 +2726,8 @@ static int spi_nor_init_params(struct spi_nor *nor)
 
 	spi_nor_manufacturer_init_params(nor);
 
-	if ((nor->info->flags & (SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
+	if ((nor->info->flags & (SPI_NOR_PARSE_SFDP |
+				 SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ |
 				 SPI_NOR_OCTAL_READ | SPI_NOR_OCTAL_DTR_READ)) &&
 	    !(nor->info->flags & SPI_NOR_SKIP_SFDP))
 		spi_nor_sfdp_init_params(nor);
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 3348e1dd1445..55fceb0ec894 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -382,6 +382,10 @@ struct flash_info {
 					 * protection bits. Usually these will
 					 * power-up in a write-protected state.
 					 */
+#define SPI_NOR_PARSE_SFDP	BIT(23) /*
+					 * Flash initialized based on the SFDP
+					 * tables.
+					 */
 
 	const struct spi_nor_otp_organization otp_org;
 
-- 
2.25.1