purism/librem_skl: add libgfxinit support

Panel settings taken from KBL FSP sample vbt.bin

Test: build/boot librem13v2/15v3 with libgfxinit init,
verify both LFB and text modes functional

Change-Id: I9582065603417e53704244e95dde51a59f709664
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36123
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/mainboard/purism/librem_skl/Kconfig

@@ -8,6 +8,7 @@ config BOARD_PURISM_BASEBOARD_LIBREM_SKL
 	select SOC_INTEL_COMMON_BLOCK_HDA_VERB
 	select SOC_INTEL_SKYLAKE
 	select SPD_READ_BY_WORD
+	select MAINBOARD_HAS_LIBGFXINIT
 	select MAINBOARD_HAS_LPC_TPM
 
 if BOARD_PURISM_BASEBOARD_LIBREM_SKL

src/mainboard/purism/librem_skl/Makefile.inc

@@ -15,3 +15,5 @@
 
 ramstage-y += ramstage.c
 ramstage-y += hda_verb.c
+
+ramstage-$(CONFIG_MAINBOARD_USE_LIBGFXINIT) += gma-mainboard.ads

src/mainboard/purism/librem_skl/gma-mainboard.ads

@@ -0,0 +1,28 @@
+--
+-- This file is part of the coreboot project.
+--
+-- This program is free software; you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation; either version 2 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+
+with HW.GFX.GMA;
+with HW.GFX.GMA.Display_Probing;
+
+use HW.GFX.GMA;
+use HW.GFX.GMA.Display_Probing;
+
+private package GMA.Mainboard is
+
+   ports : constant Port_List :=
+     (Internal,
+      HDMI1,
+      others => Disabled);
+
+end GMA.Mainboard;

src/mainboard/purism/librem_skl/variants/librem13v2/devicetree.cb

@@ -1,5 +1,13 @@
 chip soc/intel/skylake
 
+	register "gpu_pp_up_delay_ms"		  = "200"
+	register "gpu_pp_down_delay_ms"		  = " 50"
+	register "gpu_pp_cycle_delay_ms"	  = "500"
+	register "gpu_pp_backlight_on_delay_ms"	  = "  1"
+	register "gpu_pp_backlight_off_delay_ms"  = "200"
+
+	register "gpu_pch_backlight_pwm_hz"	  = "200"
+
 	# Enable deep Sx states
 	register "deep_s3_enable_ac" = "0"
 	register "deep_s3_enable_dc" = "0"

src/mainboard/purism/librem_skl/variants/librem15v3/devicetree.cb

@@ -1,5 +1,13 @@
 chip soc/intel/skylake
 
+	register "gpu_pp_up_delay_ms"		  = "200"
+	register "gpu_pp_down_delay_ms"		  = " 50"
+	register "gpu_pp_cycle_delay_ms"	  = "500"
+	register "gpu_pp_backlight_on_delay_ms"	  = "  1"
+	register "gpu_pp_backlight_off_delay_ms"  = "200"
+
+	register "gpu_pch_backlight_pwm_hz"	  = "200"
+
 	# Enable deep Sx states
 	register "deep_s3_enable_ac" = "0"
 	register "deep_s3_enable_dc" = "0"