mtd: spi-nor: Introduce SNOR_F_IO_MODE_EN_VOLATILE

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>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20201005153138.6437-9-p.yadav@ti.com

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 518d16511dee41eeb8427ba0ffc8993492017076..45d45b51705e51b5f32f5d332afafc562cc7a349 100644 (file)
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -3388,6 +3388,9 @@ 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 9a33c8d07335b1c868a3f7f95a7a24deacf24ab5..eaece1123c0bc224eff5ba74c16f70204eafb4dc 100644 (file)
--- 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;