[PATCH v16 08/15] mtd: spi-nor: Introduce SNOR_F_IO_MODE_EN_VOLATILE

Pratyush Yadav
2020-10-05T15:37:12Z

From: Tudor Ambarus <tudor.ambarus@microchip.com>

We don't want to enter a stateful mode, where a X-X-X I/O mode
is entered by setting a non-volatile bit, because in case of a
reset or a crash, once in the non-volatile mode, we may not be able
to recover in bootloaders and we may break the SPI NOR boot.

Forbid by default the I/O modes that are set via a non-volatile bit.

SPI_NOR_IO_MODE_EN_VOLATILE should be set just for the flashes that
don't define the optional SFDP SCCR Map, so that we don't pollute the
flash info flags.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
---
drivers/mtd/spi-nor/core.c | 3 +++
drivers/mtd/spi-nor/core.h | 6 ++++++
2 files changed, 9 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index b83bf5ed2b2d..e91ddb409699 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3387,6 +3387,9 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
if (info->flags & SPI_NOR_4B_OPCODES)
nor->flags |= SNOR_F_4B_OPCODES;

+ if (info->flags & SPI_NOR_IO_MODE_EN_VOLATILE)
+ nor->flags |= SNOR_F_IO_MODE_EN_VOLATILE;
+
ret = spi_nor_set_addr_width(nor);
if (ret)
return ret;
diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
index 9a33c8d07335..eaece1123c0b 100644
--- a/drivers/mtd/spi-nor/core.h
+++ b/drivers/mtd/spi-nor/core.h
@@ -26,6 +26,7 @@ enum spi_nor_option_flags {
SNOR_F_HAS_SR_TB_BIT6 = BIT(11),
SNOR_F_HAS_4BIT_BP = BIT(12),
SNOR_F_HAS_SR_BP3_BIT6 = BIT(13),
+ SNOR_F_IO_MODE_EN_VOLATILE = BIT(14),
};

struct spi_nor_read_command {
@@ -320,6 +321,11 @@ struct flash_info {
*/
#define SPI_NOR_OCTAL_DTR_READ BIT(19) /* Flash supports octal DTR Read. */
#define SPI_NOR_OCTAL_DTR_PP BIT(20) /* Flash supports Octal DTR Page Program */
+#define SPI_NOR_IO_MODE_EN_VOLATILE BIT(21) /*
+ * Flash enables the best
+ * available I/O mode via a
+ * volatile bit.
+ */

/* Part specific fixup hooks. */
const struct spi_nor_fixups *fixups;
--
2.28.0