diff options
| -rw-r--r-- | Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt | 9 | ||||
| -rw-r--r-- | drivers/mtd/spi-nor/spi-nor.c | 18 | ||||
| -rw-r--r-- | include/linux/mtd/spi-nor.h | 1 |
3 files changed, 26 insertions, 2 deletions
diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt index 956bb046e599..f03be904d3c2 100644 --- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt +++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.txt @@ -69,6 +69,15 @@ Optional properties: all chips and support for it can not be detected at runtime. Refer to your chips' datasheet to check if this is supported by your chip. +- broken-flash-reset : Some flash devices utilize stateful addressing modes + (e.g., for 32-bit addressing) which need to be managed + carefully by a system. Because these sorts of flash don't + have a standardized software reset command, and because some + systems don't toggle the flash RESET# pin upon system reset + (if the pin even exists at all), there are systems which + cannot reboot properly if the flash is left in the "wrong" + state. This boolean flag can be used on such systems, to + denote the absence of a reliable reset mechanism. Example: diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c index d9c368c44194..f028277fb1ce 100644 --- a/drivers/mtd/spi-nor/spi-nor.c +++ b/drivers/mtd/spi-nor/spi-nor.c @@ -2757,8 +2757,18 @@ static int spi_nor_init(struct spi_nor *nor) if ((nor->addr_width == 4) && (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) && - !(nor->info->flags & SPI_NOR_4B_OPCODES)) + !(nor->info->flags & SPI_NOR_4B_OPCODES)) { + /* + * If the RESET# pin isn't hooked up properly, or the system + * otherwise doesn't perform a reset command in the boot + * sequence, it's impossible to 100% protect against unexpected + * reboots (e.g., crashes). Warn the user (or hopefully, system + * designer) that this is bad. + */ + WARN_ONCE(nor->flags & SNOR_F_BROKEN_RESET, + "enabling reset hack; may not recover from unexpected reboots\n"); set_4byte(nor, nor->info, 1); + } return 0; } @@ -2781,7 +2791,8 @@ void spi_nor_restore(struct spi_nor *nor) /* restore the addressing mode */ if ((nor->addr_width == 4) && (JEDEC_MFR(nor->info) != SNOR_MFR_SPANSION) && - !(nor->info->flags & SPI_NOR_4B_OPCODES)) + !(nor->info->flags & SPI_NOR_4B_OPCODES) && + (nor->flags & SNOR_F_BROKEN_RESET)) set_4byte(nor, nor->info, 0); } EXPORT_SYMBOL_GPL(spi_nor_restore); @@ -2911,6 +2922,9 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, params.hwcaps.mask |= SNOR_HWCAPS_READ_FAST; } + if (of_property_read_bool(np, "broken-flash-reset")) + nor->flags |= SNOR_F_BROKEN_RESET; + /* Some devices cannot do fast-read, no matter what DT tells us */ if (info->flags & SPI_NOR_NO_FR) params.hwcaps.mask &= ~SNOR_HWCAPS_READ_FAST; diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h index e60da0d34cc1..c922e97f205a 100644 --- a/include/linux/mtd/spi-nor.h +++ b/include/linux/mtd/spi-nor.h @@ -235,6 +235,7 @@ enum spi_nor_option_flags { SNOR_F_S3AN_ADDR_DEFAULT = BIT(3), SNOR_F_READY_XSR_RDY = BIT(4), SNOR_F_USE_CLSR = BIT(5), + SNOR_F_BROKEN_RESET = BIT(6), }; /** |