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mtd: spi-nor: Avoid setting SRWD bit in SR if WP# signal not connected

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Setting the status register write disable (SRWD) bit in the status
register (SR) with WP# signal of the flash left floating or wrongly tied to
GND (that includes internal pull-downs), will configure the SR permanently
as read-only. If WP# signal is left floating or wrongly tied to GND, avoid
setting SRWD bit while writing the SR during flash protection.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Reviewed-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20230630142233.63585-3-amit.kumar-mahapatra@amd.com
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
This commit is contained in:
Amit Kumar Mahapatra 2023-06-30 19:52:33 +05:30 committed by Tudor Ambarus
parent cfc2928cb2
commit 18d7d01a0a
No known key found for this signature in database
GPG Key ID: 4B554F47A58D14E9
4 changed files with 12 additions and 2 deletions
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3
drivers/mtd/spi-nor/core.c
View File

@ -2844,6 +2844,9 @@ static void spi_nor_init_flags(struct spi_nor *nor)
if (of_property_read_bool(np, "broken-flash-reset"))
nor->flags |= SNOR_F_BROKEN_RESET;
if (of_property_read_bool(np, "no-wp"))
nor->flags |= SNOR_F_NO_WP;
if (flags & SPI_NOR_SWP_IS_VOLATILE)
nor->flags |= SNOR_F_SWP_IS_VOLATILE;

1
drivers/mtd/spi-nor/core.h
View File

@ -132,6 +132,7 @@ enum spi_nor_option_flags {
SNOR_F_SWP_IS_VOLATILE = BIT(13),
SNOR_F_RWW = BIT(14),
SNOR_F_ECC = BIT(15),
SNOR_F_NO_WP = BIT(16),
};
struct spi_nor_read_command {

1
drivers/mtd/spi-nor/debugfs.c
View File

@ -27,6 +27,7 @@ static const char *const snor_f_names[] = {
SNOR_F_NAME(SWP_IS_VOLATILE),
SNOR_F_NAME(RWW),
SNOR_F_NAME(ECC),
SNOR_F_NAME(NO_WP),
};
#undef SNOR_F_NAME

9
drivers/mtd/spi-nor/swp.c
View File

@ -214,8 +214,13 @@ static int spi_nor_sr_lock(struct spi_nor *nor, loff_t ofs, uint64_t len)
status_new = (status_old & ~mask & ~tb_mask) | val;
/* Disallow further writes if WP pin is asserted */
status_new |= SR_SRWD;
/*
* Disallow further writes if WP# pin is neither left floating nor
* wrongly tied to GND (that includes internal pull-downs).
* WP# pin hard strapped to GND can be a valid use case.
*/
if (!(nor->flags & SNOR_F_NO_WP))
status_new |= SR_SRWD;
if (!use_top)
status_new |= tb_mask;