ARM: dts: meson8b: ec100: wire up the RT5640 audio codec

The Realtek RT5640 codec is connected to the SoC's I2S interface.
Describe this in the .dts together with the codec's LDO1 enable GPIO so
audio can be played on the Endless Mini.
While here, add a note about the realtek,ldo1-en-gpios for which the
EC100 uses GPIO_BSD_EN. Due to driver limitations this pin cannot be
used currently.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20210717233030.331273-3-martin.blumenstingl@googlemail.com

arch/arm/boot/dts/meson8b-ec100.dts

@@ -96,6 +96,32 @@ rtc32k_xtal: rtc32k-xtal-clk {
 		#clock-cells = <0>;
 	};
 
+	sound {
+		compatible = "amlogic,gx-sound-card";
+		model = "M8B-EC100";
+
+		assigned-clocks = <&clkc CLKID_MPLL0>,
+				  <&clkc CLKID_MPLL1>,
+				  <&clkc CLKID_MPLL2>;
+		assigned-clock-rates = <270950400>,
+				       <294912000>,
+				       <393216000>;
+
+		dai-link-0 {
+			sound-dai = <&aiu AIU_CPU CPU_I2S_FIFO>;
+		};
+
+		dai-link-1 {
+			sound-dai = <&aiu AIU_CPU CPU_I2S_ENCODER>;
+			dai-format = "i2s";
+			mclk-fs = <256>;
+
+			codec-0 {
+				sound-dai = <&rt5640>;
+			};
+		};
+	};
+
 	usb_vbus: regulator-usb-vbus {
 		/*
 		 * Silergy SY6288CCAC-GP 2A Power Distribution Switch.
@@ -242,6 +268,14 @@ vddee: regulator-vddee {
 	};
 };
 
+&aiu {
+	status = "okay";
+
+	pinctrl-0 = <&i2s_am_clk_pins>, <&i2s_out_ao_clk_pins>,
+		    <&i2s_out_lr_clk_pins>, <&i2s_out_ch01_ao_pins>;
+	pinctrl-names = "default";
+};
+
 &cpu0 {
 	cpu-supply = <&vcck>;
 };
@@ -283,9 +317,19 @@ &i2c_A {
 
 	rt5640: codec@1c {
 		compatible = "realtek,rt5640";
+
 		reg = <0x1c>;
+
+		#sound-dai-cells = <0>;
+
 		interrupt-parent = <&gpio_intc>;
 		interrupts = <13 IRQ_TYPE_EDGE_BOTH>; /* GPIOAO_13 */
+
+		/*
+		 * TODO: realtek,ldo1-en-gpios is connected to GPIO_BSD_EN.
+		 * We currently cannot configure this pin correctly.
+		 * Luckily for us it's in the "right" state by default.
+		 */
 		realtek,in1-differential;
 	};
 };