Persimmon: adapt PCIe reset code copied from Inagua to actually match Persimmon

Comparing Persimmon and Inagua schematics and Coreboot code show the PCIe reset
code has been blindly copied even though it doesn't suit the Persimmon at all.

The Inagua can employ GPIOs 21, 25, 02 to manually reset devices on APU PCIe
lanes 0/1, 2, 3 respectively. (Appearently the motivation for this is to revive
buggy PCIe gen1 devices which got confused by PCIe gen2 signal training.)

However the Persimmon not only doesn't support this, it even needs these 3 pins
for the PCI interface! Instead it uses GPIO50 to reset devices on lanes 0-2 all
at once. Lane 3 is unconnected anyway.

This patch adapts the Persimmon mainboard code according to the DB-FT1 rev. D
schematics.

Change-Id: I05a657d9bf8cc59acc4f5174eb20375165c860c7
Signed-off-by: Jens Rottmann <JRottmann@LiPPERTembedded.de>
Reviewed-on: http://review.coreboot.org/2446
Tested-by: build bot (Jenkins)
Reviewed-by: Peter Stuge <peter@stuge.se>
3 files changed