ASoC: sun4i-codec: Add support for A31 playback through headphone output

The A31 has a similar codec to the A10/A20. The PCM parts are very
similar, with different register offsets. The analog paths are very
different. There are more inputs and outputs. The ADC mux has been
replaced with a proper mixer.

This patch adds support for the basic playback path of the A31 codec,
from the DAC to the headphones. Headphone detection, microphone,
signaling, other inputs/outputs and capture will be added later.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/sun4i-codec.txt

 * Allwinner A10 Codec
 
 Required properties:
-- compatible: must be either "allwinner,sun4i-a10-codec" or
-  "allwinner,sun7i-a20-codec"
+- compatible: must be one of the following compatibles:
+		- "allwinner,sun4i-a10-codec"
+		- "allwinner,sun6i-a31-codec"
+		- "allwinner,sun7i-a20-codec"
 - reg: must contain the registers location and length
 - interrupts: must contain the codec interrupt
 - dmas: DMA channels for tx and rx dma. See the DMA client binding,
@@ -17,6 +19,10 @@ Required properties:
 Optional properties:
 - allwinner,pa-gpios: gpio to enable external amplifier
 
+Required properties for the following compatibles:
+		- "allwinner,sun6i-a31-codec"
+- resets: phandle to the reset control for this device
+
 Example:
 codec: codec@01c22c00 {
 	#sound-dai-cells = <0>;
@@ -28,3 +34,15 @@ codec: codec@01c22c00 {
 	dmas = <&dma 0 19>, <&dma 0 19>;
 	dma-names = "rx", "tx";
 };
+
+codec: codec@01c22c00 {
+	#sound-dai-cells = <0>;
+	compatible = "allwinner,sun6i-a31-codec";
+	reg = <0x01c22c00 0x98>;
+	interrupts = <GIC_SPI 29 IRQ_TYPE_LEVEL_HIGH>;
+	clocks = <&ccu CLK_APB1_CODEC>, <&ccu CLK_CODEC>;
+	clock-names = "apb", "codec";
+	resets = <&ccu RST_APB1_CODEC>;
+	dmas = <&dma 15>, <&dma 15>;
+	dma-names = "rx", "tx";
+};