tree 2db31d7dda5b75d2454c92dd5edb739f0318a8bc
parent 972b105f950d800fa44f27bce090f6b89a5a84b9
author Julius Werner <jwerner@chromium.org> 1423532458 -0800
committer ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> 1423695912 +0000

rk3288: Add software I2C support

This patch adds the necessary platform glue to allow the use of
software-driven I2C bit banging on the RK3288. This is just a debugging
feature that can be used to reproduce certain I2C failure cases.

Also fix Makefile verstage linking for the feature and add some new
rk3288 IOMUX macros as needed.

BRANCH=None
BUG=None
TEST=Added "CONFIG_SOFTWARE_I2C=y" to configs/config.veyron_jerry,
wrapped Jerry's bootblock and verstage in software_i2c_attach/detach()
calls, confirmed that both PMIC and TPM could be driven correctly with
software I2C driver. Tried out different combinations of
software_i2c_wedge_ack() and software_i2c_wedge_read() on the PMIC and
observed transfer results with the hardware controller after reboot...
the worst that would happen is that the first register read-modify-write
(DCDC_ILMAX) would fail to read, but all later transfers would be fine.
Since that register is written twice (due to current BUCK1 ramp
implementation) and is not terribily important anyway, I think we don't
need to worry about wedging problems.

Change-Id: I96777300a57c85471bad20e23a455551e9970222
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/247890
Reviewed-by: Aaron Durbin <adurbin@chromium.org>