spi: intel: Allow writeable MTD partition with module param

The MTD device is blocked from writing to the SPI-NOR chip if any region
of it is write-protected, even if "writeable=1" module parameter is set.

Add ability to bypass this behaviour by introducing new module parameter
"ignore_protestion_status" which allows to rely on the write protection
mechanism of SPI-NOR chip itself, which most modern chips (since
the 1990'+) have already implemented.

Any erase/write operations performed on the write-protected section will
be rejected by the chip.

Signed-off-by: Jakub Czapiga <czapiga@google.com>
Link: https://patch.msgid.link/20250725122542.2633334-1-czapiga@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Jakub Czapiga 2025-07-25 12:25:42 +00:00 committed by Mark Brown
parent f54b69a57a
commit 87aa3c8d8c
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@ -189,6 +189,11 @@ struct intel_spi_mem_op {
static bool writeable;
module_param(writeable, bool, 0);
MODULE_PARM_DESC(writeable, "Enable write access to SPI flash chip (default=0)");
static bool ignore_protection_status;
module_param(ignore_protection_status, bool, 0);
MODULE_PARM_DESC(
ignore_protection_status,
"Do not block SPI flash chip write access even if it is write-protected (default=0)");
static void intel_spi_dump_regs(struct intel_spi *ispi)
{
@ -1248,13 +1253,15 @@ static void intel_spi_fill_partition(struct intel_spi *ispi,
continue;
/*
* If any of the regions have protection bits set, make the
* whole partition read-only to be on the safe side.
* If any of the regions have protection bits set and
* the ignore protection status parameter is not set,
* make the whole partition read-only to be on the safe side.
*
* Also if the user did not ask the chip to be writeable
* mask the bit too.
*/
if (!writeable || intel_spi_is_protected(ispi, base, limit)) {
if (!writeable || (!ignore_protection_status &&
intel_spi_is_protected(ispi, base, limit))) {
part->mask_flags |= MTD_WRITEABLE;
ispi->protected = true;
}