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15135076e2
This patch adds a module which runs on top of the SPS driver and
implements the TCG SPI TPM protocol.
Basic register read and write functions are implemented as well as
rudimentary TPM state machine (claiming/releasing locality).
An enhancement is made to the SPS driver to ensure that when the CS is
deasserted the transmit FIFO is reset too, on the off chance of the CS
going away mid transaction for whatever reason.
In this implementation the slave is guaranteed to stall the master for
a few bytes in both receive and transmit transactions, which is
further aggravated by the fact that RX FIFO threshold is set to 8
(this is the minimum number of bytes the master has to send to wake up
the slave). This could be fine tuned later, for instance made a
parameter of the receive callback registration function.
BRANCH=none
BUG=chrome-os-partner:43025
TEST=trunksd initialization (with minor changes to accommodate new
VID/DID and some status bits, to be published) succeeds with the
cr50 connected to the USB/SPI cable.
Change-Id: I28d37c3b57dde9adf59e81426efe4f58880cf0b0
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/285252