i2c_helper: Add support for the Linux I2C subsystem

See https://www.kernel.org/doc/Documentation/i2c/ for details.

This creates common interface for I2C access functions, and adds
implementation for linux I2C functions.

BUG=b:148746232
BRANCH=none
TEST=build success

Signed-off-by: Shiyu Sun <sshiyu@chromium.org>
Change-Id: Ie0487824dfb71970bede17f617dbbb30ddf78c12
Reviewed-on: https://review.coreboot.org/c/flashrom/+/39686
Tested-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
4 files changed