ASoC: sun4i-codec: Add support for A31 board level audio routing

The A31 SoC's codec has various inputs, outputs and microphone bias
supplies. These can be routed on the board in different ways, such as:

  - HPCOM may be connected to have the headphone DC coupled.

  - Microphones all use the MBIAS main microphone supply or one mic may
    use the HBIAS supply, which supports headset detection and buttons.

  - Line Out may be routed to an audio jack, or an onboard speaker amp
    with power controls.

Add support for specifying the audio routes in the device tree.
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

@@ -22,6 +22,31 @@ Optional properties:
 Required properties for the following compatibles:
 		- "allwinner,sun6i-a31-codec"
 - resets: phandle to the reset control for this device
+- allwinner,audio-routing: A list of the connections between audio components.
+			   Each entry is a pair of strings, the first being the
+			   connection's sink, the second being the connection's
+			   source. Valid names include:
+
+			   Audio pins on the SoC:
+			   "HP"
+			   "HPCOM"
+			   "LINEIN"
+			   "LINEOUT"
+			   "MIC1"
+			   "MIC2"
+			   "MIC3"
+
+			   Microphone biases from the SoC:
+			   "HBIAS"
+			   "MBIAS"
+
+			   Board connectors:
+			   "Headphone"
+			   "Headset Mic"
+			   "Line In"
+			   "Line Out"
+			   "Mic"
+			   "Speaker"
 
 Example:
 codec: codec@01c22c00 {
@@ -45,4 +70,12 @@ codec: codec@01c22c00 {
 	resets = <&ccu RST_APB1_CODEC>;
 	dmas = <&dma 15>, <&dma 15>;
 	dma-names = "rx", "tx";
+	allwinner,audio-routing =
+		"Headphone", "HP",
+		"Speaker", "LINEOUT",
+		"LINEIN", "Line In",
+		"MIC1",	"MBIAS",
+		"MIC1", "Mic",
+		"MIC2", "HBIAS",
+		"MIC2", "Headset Mic";
 };

sound/soc/sunxi/sun4i-codec.c

@@ -1104,9 +1104,19 @@ static struct snd_soc_card *sun4i_codec_create_card(struct device *dev)
 	return card;
 };
 
+static const struct snd_soc_dapm_widget sun6i_codec_card_dapm_widgets[] = {
+	SND_SOC_DAPM_HP("Headphone", NULL),
+	SND_SOC_DAPM_LINE("Line In", NULL),
+	SND_SOC_DAPM_LINE("Line Out", NULL),
+	SND_SOC_DAPM_MIC("Headset Mic", NULL),
+	SND_SOC_DAPM_MIC("Mic", NULL),
+	SND_SOC_DAPM_SPK("Speaker", sun4i_codec_spk_event),
+};
+
 static struct snd_soc_card *sun6i_codec_create_card(struct device *dev)
 {
 	struct snd_soc_card *card;
+	int ret;
 
 	card = devm_kzalloc(dev, sizeof(*card), GFP_KERNEL);
 	if (!card)
@@ -1118,6 +1128,13 @@ static struct snd_soc_card *sun6i_codec_create_card(struct device *dev)
 
 	card->dev		= dev;
 	card->name		= "A31 Audio Codec";
+	card->dapm_widgets	= sun6i_codec_card_dapm_widgets;
+	card->num_dapm_widgets	= ARRAY_SIZE(sun6i_codec_card_dapm_widgets);
+	card->fully_routed	= true;
+
+	ret = snd_soc_of_parse_audio_routing(card, "allwinner,audio-routing");
+	if (ret)
+		dev_warn(dev, "failed to parse audio-routing: %d\n", ret);
 
 	return card;
 };