Marvell Xfer overlay extends xSPI capabilities to support non-memory SPI
operations. The Marvell overlay, combined with a generic command, allows
for full-duplex SPI transactions. It also enables transactions with
undetermined lengths using the cs_hold parameter and the ability to
extend CS signal assertion, even if the xSPI block requests CS signal
de-assertion.
Marvell overlay is using part of xSPI for writing data into device, and
additional hardware block to read data from the device. To do that xSPI
will trigger 1 byte generic command followed by data sequence. In same
time overlay block will monitor MISO pin to read data from the device.
Due to that SDMA data start will be shifted by 1 byte.
Signed-off-by: Witold Sadowski <wsadowski@marvell.com>
Link: https://patch.msgid.link/20240724154739.582367-7-wsadowski@marvell.comSigned-off-by: Mark Brown <broonie@kernel.org>