IBM Power processors have a SPI controller that can be accessed
over FSI from a service processor. Document it.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://msgid.link/r/20240514192630.152747-1-eajames@linux.ibm.comSigned-off-by: Mark Brown <broonie@kernel.org>