mb/dell: Add Latitude E6420 (Sandy Bridge)

Mainboard is PAL50/LA-6591P (UMA). The version with an Nvidia dGPU was
not tested. I do not physically have this system; someone with physical
access to one sent me the output of autoport which I then modified to
produce this port. I was also sent the VBT binary, which was obtained
from `/sys/kernel/debug/dri/0/i915_vbt` while running version A25 of the
vendor firmware.

This was originally tested and found to be working as a standalone board
port in Libreboot, but this variant based port in upstream coreboot has
not been tested.

This can be internally flashed by sending a command to the EC, which
causes the EC to pull the FDO pin low and the firmware to skip setting
up any chipset based write protections [1]. The EC is the SMSC MEC5055,
which seems to be compatible with the existing MEC5035 code.

[1] https://gitlab.com/nic3-14159/dell-flash-unlock

Change-Id: Ic48d9ea58172a5b13958c8afebcb19c8929c4394
Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82126
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

0 files changed, 0 insertions, 0 deletions