Change in coreboot[master]: mb/google/volteer: Create APIs for USB-C DP alternate mode support

[Derek Huang (Code Review)]

Attention is currently required from: Derek Huang, Zhuohao Lee, Curtis Chen.
Hello build bot (Jenkins), Tim Wawrzynczak, Zhuohao Lee, Curtis Chen,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/57490

to look at the new patch set (#6).

Change subject: mb/google/volteer: Create APIs for USB-C DP alternate mode support
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mb/google/volteer: Create APIs for USB-C DP alternate mode support

1. API to detect if any DP device is connected
2. API to wait for HPD ready
3. API to send the command from AP to EC to enter DP mode.

TEST=select ENABLE_TCSS_DISPLAY_DETECTION in Kconfig.name. Build
coreboot and update your system. Boot the system, external display
connected to USB-C port should show screen in developer mode or
recovery mode

Signed-off-by: Derek Huang 
Change-Id: If73e0ce0154f0dc4f81dc449b7ec89316fe93814
---
M src/mainboard/google/volteer/mainboard.c
1 file changed, 102 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/90/57490/6