x86: Add generic EFI payload support

It is possible to create a generic EFI payload for all x86 boards.
The payload is configured to include as many generic drivers as
possible. All stuff that touches low-level initialization are not
allowed as such is the EFI BIOS's responsibility. Platform specific
drivers (like gpio, spi, etc) are not included.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/Makefile b/arch/x86/dts/Makefile
index 7379774..9872c04 100644
--- a/arch/x86/dts/Makefile
+++ b/arch/x86/dts/Makefile
@@ -11,6 +11,7 @@
 	dfi-bt700-q7x-151.dtb \
 	edison.dtb \
 	efi.dtb \
+	efi-x86_payload.dtb \
 	galileo.dtb \
 	minnowmax.dtb \
 	qemu-x86_i440fx.dtb \
diff --git a/arch/x86/dts/efi-x86_payload.dts b/arch/x86/dts/efi-x86_payload.dts
new file mode 100644
index 0000000..137bde5
--- /dev/null
+++ b/arch/x86/dts/efi-x86_payload.dts
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * Generic EFI payload device tree for x86 targets
+ */
+
+/dts-v1/;
+
+/include/ "skeleton.dtsi"
+/include/ "serial.dtsi"
+/include/ "keyboard.dtsi"
+/include/ "rtc.dtsi"
+/include/ "tsc_timer.dtsi"
+
+/ {
+	model = "EFI x86 Payload";
+	compatible = "efi,x86-payload";
+
+	aliases {
+		serial0 = &serial;
+	};
+
+	config {
+		silent_console = <0>;
+	};
+
+	chosen {
+		stdout-path = "/serial";
+	};
+
+	pci {
+		compatible = "pci-x86";
+		u-boot,dm-pre-reloc;
+	};
+};