soc/intel/tigerlake: Hook up GMA ACPI brightness controls

Add function needed to generate ACPI backlight control SSDT, along with
Kconfig values for accessing the registers.

Tested by adding gfx register on system76/gaze16 and booting Windows.
Display settings has a brightness setting, and can change the brightness
level.

Change-Id: Id8b14c0b4a7a681dc6cb95778c12a006a7e31373
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57823
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/soc/intel/tigerlake/Kconfig

@@ -305,4 +305,16 @@ config PCIEXP_HOTPLUG_PREFETCH_MEM
 
 endif # SOC_INTEL_ENABLE_USB4_PCIE_RESOURCES
 
+config INTEL_GMA_BCLV_OFFSET
+	default 0xc8258
+
+config INTEL_GMA_BCLV_WIDTH
+	default 32
+
+config INTEL_GMA_BCLM_OFFSET
+	default 0xc8254
+
+config INTEL_GMA_BCLM_WIDTH
+	default 32
+
 endif

src/soc/intel/tigerlake/Makefile.inc

@@ -31,6 +31,7 @@ ramstage-y += elog.c
 ramstage-y += espi.c
 ramstage-y += finalize.c
 ramstage-y += fsp_params.c
+ramstage-y += graphics.c
 ramstage-y += lockdown.c
 ramstage-y += lpm.c
 ramstage-y += me.c

src/soc/intel/tigerlake/chip.h

@@ -4,6 +4,7 @@
 #define _SOC_CHIP_H_
 
 #include <drivers/i2c/designware/dw_i2c.h>
+#include <drivers/intel/gma/gma.h>
 #include <intelblocks/cfg.h>
 #include <intelblocks/gpio.h>
 #include <intelblocks/gspi.h>
@@ -532,6 +533,9 @@ struct soc_intel_tigerlake_config {
 	 *
 	 */
 	bool external_bypass;
+
+	/* i915 struct for GMA backlight control */
+	struct i915_gpu_controller_info gfx;
 };
 
 typedef struct soc_intel_tigerlake_config config_t;

src/soc/intel/tigerlake/graphics.c

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <intelblocks/graphics.h>
+#include <soc/ramstage.h>
+
+const struct i915_gpu_controller_info *
+intel_igd_get_controller_info(const struct device *const dev)
+{
+	const struct soc_intel_tigerlake_config *const chip = dev->chip_info;
+	return &chip->gfx;
+}