ASoC: tegra: tegra_wm8903: Support DAPM events for built-in microphone

The enable-GPIO needs to be toggled on a DAPM event in order to turn
microphone ON/OFF, otherwise microphone won't work.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20200320205504.30466-3-digetx@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/tegra/tegra_wm8903.c

@@ -143,14 +143,32 @@ static int tegra_wm8903_event_hp(struct snd_soc_dapm_widget *w,
 	return 0;
 }
 
+static int tegra_wm8903_event_int_mic(struct snd_soc_dapm_widget *w,
+				      struct snd_kcontrol *k, int event)
+{
+	struct snd_soc_dapm_context *dapm = w->dapm;
+	struct snd_soc_card *card = dapm->card;
+	struct tegra_wm8903 *machine = snd_soc_card_get_drvdata(card);
+
+	if (!gpio_is_valid(machine->gpio_int_mic_en))
+		return 0;
+
+	gpio_set_value_cansleep(machine->gpio_int_mic_en,
+				SND_SOC_DAPM_EVENT_ON(event));
+
+	return 0;
+}
+
 static const struct snd_soc_dapm_widget tegra_wm8903_dapm_widgets[] = {
 	SND_SOC_DAPM_SPK("Int Spk", tegra_wm8903_event_int_spk),
 	SND_SOC_DAPM_HP("Headphone Jack", tegra_wm8903_event_hp),
 	SND_SOC_DAPM_MIC("Mic Jack", NULL),
+	SND_SOC_DAPM_MIC("Int Mic", tegra_wm8903_event_int_mic),
 };
 
 static const struct snd_kcontrol_new tegra_wm8903_controls[] = {
 	SOC_DAPM_PIN_SWITCH("Int Spk"),
+	SOC_DAPM_PIN_SWITCH("Int Mic"),
 };
 
 static int tegra_wm8903_init(struct snd_soc_pcm_runtime *rtd)