sun50i: a64: Add Olimex A64-Teres-I board initial support

Olimex A64-Teres-I board is a mainboard (the only one so far)
for Olimex Teres-I DIY laptop kit.

Key features:
- Allwinner A64 Cortex-A53
- Mali-400MP2 GPU
- AXP803 PMIC
- 2GB DDR3 RAM
- MicroSD Slot
- 16GB eMMC Flash
- eDP LCD display
- HDMI
- USB Host
- Battery management
- 5V DC power supply
- Certified Open Source Hardware (OSHW)

Works:
- i2C
- MMC/SD
- PWM backlight

Known broken:
- Internal keyboard (seems to be because the keyboard firmware loads a
bootloader first, and then disconnects bootloader and connect real
keyboard). External ones connected to the USB port work fine.

This patch enables support for the A64-Teres-I board to u-boot,
including enabling screen backlight (lacking from Linux device-tree).

Linux commit details about the sun50i-a64-teres-i.dts sync:
"arm64: dts: allwinner: a64: Rename uart0_pins_a label to uart0_pb_pins"
(sha1: d91ebb95b96c8840932dc3a10c9f243712555467)

Cosmetic warnings regarding whitespace and placement of SPDX notice for
dts file was ignored.

config and .dtsi file are adapted from pinebook files.

Tested-by: Jonas Smedegaard <dr@jones.dk>
Signed-off-by: Jonas Smedegaard <dr@jones.dk>
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
[jagan: move board entry in MAINTAINERS file at proper position]
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/arch/arm/dts/sun50i-a64-teres-i-u-boot.dtsi b/arch/arm/dts/sun50i-a64-teres-i-u-boot.dtsi
new file mode 100644
index 0000000..1a64b7d
--- /dev/null
+++ b/arch/arm/dts/sun50i-a64-teres-i-u-boot.dtsi
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
+/*
+ * Copyright (C) 2019 Vasily Khoruzhick <anarsoul@gmail.com>
+ *
+ */
+
+#include "sunxi-u-boot.dtsi"
+
+/ {
+	vdd_bl: regulator@0 {
+		compatible = "regulator-fixed";
+		regulator-name = "bl-3v3";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		gpio = <&pio 7 6 GPIO_ACTIVE_HIGH>; /* PH6 */
+		enable-active-high;
+	};
+
+	backlight: backlight {
+		compatible = "pwm-backlight";
+		pwms = <&pwm 0 50000 0>;
+		brightness-levels = <0 5 10 15 20 30 40 55 70 85 100>;
+		default-brightness-level = <2>;
+		enable-gpios = <&pio 3 23 GPIO_ACTIVE_HIGH>; /* PD23 */
+		power-supply = <&vdd_bl>;
+	};
+};
+
+/* The ANX6345 eDP-bridge is on i2c */
+&i2c0 {
+	anx6345: edp-bridge@38 {
+		compatible = "analogix,anx6345";
+		reg = <0x38>;
+		reset-gpios = <&pio 3 24 GPIO_ACTIVE_LOW>; /* PD24 */
+		status = "okay";
+	};
+};
+
+&pwm {
+	status = "okay";
+};