drivers/gfx/nvidia: Add driver for NVIDIA GPU

Add a driver for laptops with NVIDIA Optimus (hybrid) graphics. The
driver provides ACPI support for dynamically powering on and off the
GPU, NVIDIA Dynamic Boost support, and a function for enabling the GPU
power in romstage.

References:
- DG-09845-001: NVIDIA GN20/QN20 Hardware Design Guide
- DG-09954-001: NVIDIA GN20/QN20 Software Design Guide

Change-Id: I2dec7aa2c8db7994f78a7cc1220502676e248465
Signed-off-by: Jeremy Soller <jeremy@system76.com>
Signed-off-by: Tim Crawford <tcrawford@system76.com>

src/drivers/gfx/nvidia/acpi/coffeelake.asl

@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* NVIDIA GC6 on CFL and CML CPU PCIe ports */
+
+// Memory mapped PCI express config space
+OperationRegion (PCIC, SystemMemory, CONFIG_ECAM_MMCONF_BASE_ADDRESS + (CONFIG_DRIVERS_GFX_NVIDIA_BRIDGE << 15), 0x1000)
+
+Field (PCIC, ByteAcc, NoLock, Preserve) {
+	PVID,   16,
+	PDID,   16,
+
+	Offset (0x248),
+		,   7,
+	L23E,   1,      /* L23_Rdy Entry Request */
+	L23R,   1,      /* L23_Rdy to Detect Transition */
+
+	Offset (0xC20),
+		,   4,
+	P0AP,   2,      /* Additional power savings */
+
+	Offset (0xC38),
+		,   3,
+	P0RM,   1,      /* Robust squelch mechanism */
+}
+
+// Enter L23
+Method (DL23, 0, Serialized) {
+	Printf("      GPU PORT DL23 START")
+
+	L23E = 1
+	Sleep (16)
+	Local0 = 0
+	While (L23E) {
+		If ((Local0 > 4)) {
+			Break
+		}
+
+		Sleep (16)
+		Local0++
+	}
+
+	P0RM = 1
+	P0AP = 3
+
+	Printf("      GPU PORT DL23 FINISH")
+}
+
+// Exit L23
+Method (L23D, 0, Serialized) {
+	Printf("      GPU PORT L23D START")
+
+	L23R = 1
+	Sleep (16)
+	Local0 = 0
+	While (L23R) {
+		If ((Local0 > 4)) {
+			Break
+		}
+
+		Sleep (16)
+		Local0++
+	}
+
+	P0RM = 0
+	P0AP = 0
+
+	Printf("      GPU PORT L23D FINISH")
+}
+
+// Main power resource
+PowerResource (PWRR, 0, 0) {
+	Name (_STA, 1)
+
+	Method (_ON, 0, Serialized) {
+		Printf("GPU PORT PWRR._ON")
+
+		^^DEV0._ON()
+
+		_STA = 1
+	}
+
+	Method (_OFF, 0, Serialized) {
+		Printf("GPU PORT PWRR._OFF")
+
+		^^DEV0._OFF()
+
+		_STA = 0
+	}
+}
+
+// Power resources for entering D0
+Name (_PR0, Package () { PWRR })
+
+// Power resources for entering D3
+Name (_PR3, Package () { PWRR })
+
+#include "common/gpu.asl"