ASoC: Implement WM8994 DAC data source muxes

Allow selection of the channel used for input to the AIFnDAC signals.
This isn't integrated into DAPM since we treat the data as a single
mono channel until just beyond this selection so it ends up having
no visible effect on the routing.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>

sound/soc/codecs/wm8994.c

@@ -2072,6 +2072,22 @@ static int wm8994_get_retune_mobile_enum(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
+static const char *aifdac_src_text[] = {
+	"Left", "Right"
+};
+
+static const struct soc_enum aif1dacl_src =
+	SOC_ENUM_SINGLE(WM8994_AIF1_CONTROL_2, 15, 2, aifdac_src_text);
+
+static const struct soc_enum aif1dacr_src =
+	SOC_ENUM_SINGLE(WM8994_AIF1_CONTROL_2, 14, 2, aifdac_src_text);
+
+static const struct soc_enum aif2dacl_src =
+	SOC_ENUM_SINGLE(WM8994_AIF2_CONTROL_2, 15, 2, aifdac_src_text);
+
+static const struct soc_enum aif2dacr_src =
+	SOC_ENUM_SINGLE(WM8994_AIF2_CONTROL_2, 14, 2, aifdac_src_text);
+
 static const struct snd_kcontrol_new wm8994_snd_controls[] = {
 SOC_DOUBLE_R_TLV("AIF1ADC1 Volume", WM8994_AIF1_ADC1_LEFT_VOLUME,
 		 WM8994_AIF1_ADC1_RIGHT_VOLUME,
@@ -2083,6 +2099,11 @@ SOC_DOUBLE_R_TLV("AIF2ADC Volume", WM8994_AIF2_ADC_LEFT_VOLUME,
 		 WM8994_AIF2_ADC_RIGHT_VOLUME,
 		 1, 119, 0, digital_tlv),
 
+SOC_ENUM("AIF1DACL Source", aif1dacl_src),
+SOC_ENUM("AIF1DACR Source", aif1dacr_src),
+SOC_ENUM("AIF2DACL Source", aif1dacl_src),
+SOC_ENUM("AIF2DACR Source", aif1dacr_src),
+
 SOC_DOUBLE_R_TLV("AIF1DAC1 Volume", WM8994_AIF1_DAC1_LEFT_VOLUME,
 		 WM8994_AIF1_DAC1_RIGHT_VOLUME, 1, 96, 0, digital_tlv),
 SOC_DOUBLE_R_TLV("AIF1DAC2 Volume", WM8994_AIF1_DAC2_LEFT_VOLUME,