spi: spi-mem: Protect dirmap_create() with spi_mem_access_start/end

spi: spi-mem: Protect dirmap_create() with spi_mem_access_start/end

spi_mem_dirmap_create() may reconfigure controller-wide settings,
which can interfere with concurrent transfers to other devices
sharing the same SPI controller but using different chip selects.

Wrap the ->dirmap_create() callback with spi_mem_access_start() and
spi_mem_access_end() to serialize access and prevent cross-CS
interference during dirmap creation.

This patch has been verified on a setup where a SPI TPM is connected
to CS0 of a SPI controller, while a SPI NOR flash is connected to CS1
of the same controller. Without this patch, spi_mem_dirmap_create()
for the SPI NOR flash interferes with ongoing SPI TPM data transfers,
resulting in failure to create the TPM device. This was tested on an
ASPEED AST2700 EVB.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@aspeedtech.com>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Link: https://patch.msgid.link/20260120123005.1392071-2-chin-ting_kuo@aspeedtech.com
Signed-off-by: Mark Brown <broonie@kernel.org>