Add support for the cr50 TPM used in apollolake chromebooks.
This requires custom handling due to chip limitations, which
may be revisited but are needed to get things working today.
- timeouts need to be longer
- must use the older style write+wait+read read protocol
- all 4 bytes of status register must be read at once
- same limitation applies when reading burst count from status reg
- burst count max is 63 bytes, and burst count behaves
slightly differently than other I2C TPMs
- TPM expects the host to drain the full burst count (63 bytes)
from the FIFO on a read
Luckily the existing driver provides most abstraction needed to
make this work seamlessly. To maximize code re-use the support
for cr50 is added directly instead of as a separate driver and the
style is kept similar to the rest of the driver code.
This was tested with the cr50 TPM on a reef board with vboot
use of TPM for secdata storage and factory initialization.
Change-Id: I9b0bc282e41e779da8bf9184be0a11649735a101
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/16396
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@googlemail.com>
ffa765f6eb