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Subject[PATCH 5/5] mtd: spi-nor: add Kconfig option to disable write protection at power-up
Date
From: Tudor Ambarus <tudor.ambarus@microchip.com>

Some spi-nor flashes come write protected by default after a
power-on sequence to avoid destructing commands (erase, write)
during power-up.

Backward compatibility imposes to disable the write protection
at power-up by default. Add a Kconfig option to let the user
benefit of the power-up write protection.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
drivers/mtd/spi-nor/Kconfig | 8 ++++++++
drivers/mtd/spi-nor/spi-nor.c | 2 ++
2 files changed, 10 insertions(+)

diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig
index 6de83277ce8b..b550e10657f1 100644
--- a/drivers/mtd/spi-nor/Kconfig
+++ b/drivers/mtd/spi-nor/Kconfig
@@ -22,6 +22,14 @@ config MTD_SPI_NOR_USE_4K_SECTORS
Please note that some tools/drivers/filesystems may not work with
4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).

+config MTD_SPI_NOR_DISABLE_POWER_UP_WRITE_PROTECTION
+ bool "Disable write protection during power-up"
+ default y
+ help
+ Some spi-nor flashes are write protected by default after a power-on
+ reset cycle, in order to avoid inadvertend writes during power-up.
+ Disable the write protection during power-up.
+
config SPI_ASPEED_SMC
tristate "Aspeed flash controllers in SPI mode"
depends on ARCH_ASPEED || COMPILE_TEST
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index ffb53740031c..e5627fa6b1cd 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -4049,6 +4049,7 @@ static int spi_nor_init(struct spi_nor *nor)
{
int err;

+#ifdef CONFIG_MTD_SPI_NOR_DISABLE_POWER_UP_WRITE_PROTECTION
/*
* Atmel, SST, Intel/Numonyx, and others serial NOR tend to power up
* with the software protection bits set.
@@ -4082,6 +4083,7 @@ static int spi_nor_init(struct spi_nor *nor)
return err;
}
}
+#endif

if (nor->quad_enable) {
err = nor->quad_enable(nor);
--
2.9.5
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