[L] Change in coreboot[main]: mb/dell: Add Latitude E5520 (Sandy Bridge)

[Nicholas Chin (Code Review)]

Nicholas Chin has uploaded a new patch set (#3). ( https://review.coreboot.org/c/coreboot/+/82128?usp=email )

Change subject: mb/dell: Add Latitude E5520 (Sandy Bridge)
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mb/dell: Add Latitude E5520 (Sandy Bridge)

Mainboard is Krug 15". 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
A14 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: Ic9bfc028d4b8ae01ccc019157bb53e7764671134
Signed-off-by: Nicholas Chin 
---
M src/mainboard/dell/snb_ivb_latitude/Kconfig
M src/mainboard/dell/snb_ivb_latitude/Kconfig.name
A src/mainboard/dell/snb_ivb_latitude/variants/e5520/data.vbt
A src/mainboard/dell/snb_ivb_latitude/variants/e5520/early_init.c
A src/mainboard/dell/snb_ivb_latitude/variants/e5520/gpio.c
A src/mainboard/dell/snb_ivb_latitude/variants/e5520/hda_verb.c
A src/mainboard/dell/snb_ivb_latitude/variants/e5520/overridetree.cb
7 files changed, 294 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/28/82128/3