ec/google: Support ChromeOS EC on SPI bus.

For devices with ChromeOS EC on SPI bus, use the standard SPI driver interface
(see spi-generic.h) to exchange data.

Note: Only EC protocol v3 is supported for SPI bus.

Change-Id: Ia8dcdecd125a2bd7424d0c7560e046b6d6988a03
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/3751
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
3 files changed