(Re)configure various pads found by dissecting a dead board and vendor
firmware, as well as the BMC firmware:
- GPP_B14: input connected to jumper JBR1 - could be used to implement
"BIOS Recovery" ("Top-Block Swap") functionality; external pull-up
- GPP_C20: output to BMC alert CPU_THROTTLED# - can be used to notify
the BMC about a thermal throttling event. Not implemented in vendor
firmware.
- GPP_C23: input connected to the CPU's CATERR# output; external pull-up
Not actively used by vendor firmware.
- GPP_D1: output connected to on-board and front panel power LEDs
- GPP_D18: output connected to PERST# of both CPU PCIe Slots. Can be
used for testing/debugging only, since it resets both slots at once.
Not actively used by vendor firmware.
- GPP_D19: output connected to PERST# of both PCH PCIe Slots. Can be
used for testing/debugging only, since it resets both slots at once.
Not actively used by vendor firmware.
- GPP_D22: input connected to the BMC enable/disable jumper JPB1; Will
be used later in CB:48096 and CB:48097; external pull-up
- GPP_G0 - GPP_G3: dedicated/integrated CPU switching; probably not
useful, since the IGD is not connected to any ports on this board.
External pulls ensure correct function of a dGPU even without driving
the gpios. Not used by vendor firmware.
- GPP_G12 - GPP_G16: inputs for binary SKU_ID; external pulls
- GPP_G20: PWRFAIL# input from JPI2C1 (pin 3); external pull-up; Not
used by vendor firmware.
Also add comments for documentation. While at it, mark ME-owned pads as
reserved.
Change-Id: I9f9328e9ce6f7e291b171f776bb98bc617b64b93
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48098
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Christian Walter <christian.walter@9elements.com>
7f623f8e46