drivers/intel/gma: Hook up libgfxinit in romstage

A mainboard port needs to:

- select `CONFIG_MAINBOARD_HAS_EARLY_LIBGFXINIT'

- implement the Ada package `GMA.Mainboard' with a single function
  `ports' that returns a list of ports to be probed for displays.

- set the desired `GFX_GMA_DEFAULT_MMIO' IO memory address to use
  in romstage (and ramstage) for the graphic device.

BUG=b:252792591
BRANCH=firmware-brya-14505.B
TEST=libgfxinit compiles in romstage.
     libgfxinit successfully executes in romstage and ramstage using
     the requested MMIO setting on skolas.

Change-Id: I3c2101de10dc5df54fe873e43bbe0f1c4dccff44
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70276
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/device/Kconfig

@@ -4,7 +4,7 @@ menu "Devices"
 
 config HAVE_VGA_TEXT_FRAMEBUFFER
 	bool
-	depends on !NO_GFX_INIT
+	depends on !(NO_GFX_INIT && NO_EARLY_GFX_INIT)
 	help
 	  Selected by graphics drivers that support legacy VGA text mode.
 
@@ -58,6 +58,13 @@ config MAINBOARD_HAS_LIBGFXINIT
 	  Selected by mainboards that implement support for `libgfxinit`.
 	  Usually this requires a list of ports to be probed for displays.
 
+config MAINBOARD_HAS_EARLY_LIBGFXINIT
+	def_bool n
+	help
+	  Selected by mainboards that implement early (cache-as-ram
+	  stage) support of `libgfxinit`. Usually this requires a list
+	  of ports to be probed for displays.
+
 choice
 	prompt "Graphics initialization"
 	default NO_GFX_INIT if VGA_ROM_RUN_DEFAULT && PAYLOAD_SEABIOS
@@ -117,6 +124,28 @@ config NO_GFX_INIT
 
 endchoice
 
+choice
+	prompt "Early (romstage) graphics initialization"
+	default MAINBOARD_USE_EARLY_LIBGFXINIT if MAINBOARD_HAS_EARLY_LIBGFXINIT
+	default NO_EARLY_GFX_INIT
+
+config NO_EARLY_GFX_INIT
+	bool "None"
+	help
+	  Select this to not perform any graphics initialization at
+	  romstage.
+
+config MAINBOARD_USE_EARLY_LIBGFXINIT
+	bool "Use libgfxinit"
+	depends on MAINBOARD_HAS_EARLY_LIBGFXINIT
+	select ROMSTAGE_VGA
+	help
+	  Use the SPARK library `libgfxinit` for the romstage native
+	  graphics initialization. This requires an Ada
+	  toolchain. Graphics at romstage is limited to VGA text mode.
+
+endchoice
+
 config PRE_GRAPHICS_DELAY_MS
 	int "Graphics initialization delay in ms"
 	default 0