arm64: dts: sun50i-a64-pinephone: Enable LCD support on PinePhone

PinePhone uses PWM backlight and a XBD599 LCD panel over DSI for
display.

Backlight levels curve was optimized by Martijn Braam using a
lux meter.

Add its device nodes.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Martijn Braam <martijn@brixit.nl>
Signed-off-by: Ondrej Jirman <megous@megous.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20200702081432.1727696-2-megous@megous.comSigned-off-by: Maxime Ripard <maxime@cerno.tech>

arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone-1.1.dts

@@ -9,3 +9,22 @@ / {
 	model = "Pine64 PinePhone Braveheart (1.1)";
 	compatible = "pine64,pinephone-1.1", "allwinner,sun50i-a64";
 };
+
+&backlight {
+	power-supply = <&reg_ldo_io0>;
+	/*
+	 * PWM backlight circuit on this PinePhone revision was changed since
+	 * 1.0, and the lowest PWM duty cycle that doesn't lead to backlight
+	 * being off is around 20%. Duty cycle for the lowest brightness level
+	 * also varries quite a bit between individual boards, so the lowest
+	 * value here was chosen as a safe default.
+	 */
+	brightness-levels = <
+		774  793  814  842
+		882  935  1003 1088
+		1192 1316 1462 1633
+		1830 2054 2309 2596
+		2916 3271 3664 4096>;
+	num-interpolated-steps = <50>;
+	default-brightness-level = <400>;
+};

arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi

@@ -16,6 +16,13 @@ aliases {
 		serial0 = &uart0;
 	};
 
+	backlight: backlight {
+		compatible = "pwm-backlight";
+		pwms = <&r_pwm 0 50000 PWM_POLARITY_INVERTED>;
+		enable-gpios = <&pio 7 10 GPIO_ACTIVE_HIGH>; /* PH10 */
+		/* Backlight configuration differs per PinePhone revision. */
+	};
+
 	chosen {
 		stdout-path = "serial0:115200n8";
 	};
@@ -84,6 +91,28 @@ &dai {
 	status = "okay";
 };
 
+&de {
+	status = "okay";
+};
+
+&dphy {
+	status = "okay";
+};
+
+&dsi {
+	vcc-dsi-supply = <&reg_dldo1>;
+	status = "okay";
+
+	panel@0 {
+		compatible = "xingbangda,xbd599";
+		reg = <0>;
+		reset-gpios = <&pio 3 23 GPIO_ACTIVE_LOW>; /* PD23 */
+		iovcc-supply = <&reg_dldo2>;
+		vcc-supply = <&reg_ldo_io0>;
+		backlight = <&backlight>;
+	};
+};
+
 &ehci0 {
 	status = "okay";
 };
@@ -188,6 +217,10 @@ &r_pio {
 	 */
 };
 
+&r_pwm {
+	status = "okay";
+};
+
 &r_rsb {
 	status = "okay";