spi: Add TPM HW flow flag
TPM specification [1] defines flow control over SPI. Client device can
insert a wait state on MISO when address is transmitted by controller
on MOSI. Detecting the wait state in software is only possible for
full duplex controllers. For controllers that support only half-
duplex, the wait state detection needs to be implemented in hardware.
Add a flag SPI_TPM_HW_FLOW for TPM device to set when software flow
control is not possible and hardware flow control is expected from
SPI controller.
Reference:
[1] https://trustedcomputinggroup.org/resource/pc-client-platform-tpm
-profile-ptp-specification/
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20230421091309.2672-2-kyarlagadda@nvidia.com
Signed-off-by: Mark Brown <broonie@kernel.org>
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