drivers/i2c/tpm: Add support for cr50 TPM

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>

0 files changed, 0 insertions, 0 deletions