servo_v4: Enable VBUS passthrough from CHG to DUT port

This CL adds support for the DUT port to advertise different current
levels via the Rp resistor selection. The default setting is USB (500
mA).

The board_manage_chg_port function relies on the off->on transitions
only occurring when the CHG port is in a steady state condition. When
the charger being used supports PD messaging, the entry point
pd_set_input_current_limit() which is called after receiving a PS_RDY
message. For TypeC only chargers, the entry point is
typec_set_input_current_limit() which is called from SNK_DISOVERY
after only after the max number of hard reset attempts have been
attempted. This is intended to prevent this entry point from being
called when a USB PD charger is connected and the CHG port enters
SNK_DISCOVERY.

When the CHG port Vbus transitions from off->on, a src_pdo is updated
to reflect the current contract on the CHG port and this src_pdo can
then be used by the DUT port when either a new connection is done or
to update it's existing contract.

BUG=b:35586526
BRANCH=servo
TEST=Manual
Connected servo_v4 DUT port to Reef with no charger
connected. Verified that it connects, and CCD mode in Reef is enabled
(H1 console is available) and that only 500 mA charging current is
advertised. Then connected a 20V and 15V USB PD charger to the CHG
port. In each case verified that the DUT renegotiates to the 20 and
15V level respectively. Repated the test with Guppy and verifed that
VBUS is at 5V 3A. When Guppy is removed, then the DUT connection
reverts back to the host as the VBUS source.

Change-Id: I1a5eb346bbe1f0d586cb8b7bb24d77ff713fbf3c
Signed-off-by: Scott <scollyer@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/449954
Commit-Ready: Scott Collyer <scollyer@chromium.org>
Tested-by: Scott Collyer <scollyer@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

0 files changed, 0 insertions, 0 deletions