ASoC: nau8821: add new widget to control system clock

Add new widget to control system clock for power saving.
Signed-off-by: Wallace Lin <savagecin0@gmail.com>
Signed-off-by: Wallace Lin <sjlin0@nuvoton.com>
Link: https://lore.kernel.org/r/20220719084047.11572-1-savagecin@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/nau8821.c

@@ -36,6 +36,7 @@
 
 static int nau8821_configure_sysclk(struct nau8821 *nau8821,
 	int clk_id, unsigned int freq);
+static bool nau8821_is_jack_inserted(struct regmap *regmap);
 
 struct nau8821_fll {
 	int mclk_src;
@@ -495,7 +496,33 @@ static int nau8821_output_dac_event(struct snd_soc_dapm_widget *w,
 	return 0;
 }
 
+static int system_clock_control(struct snd_soc_dapm_widget *w,
+				struct snd_kcontrol *k, int  event)
+{
+	struct snd_soc_component *component =
+		snd_soc_dapm_to_component(w->dapm);
+	struct nau8821 *nau8821 = snd_soc_component_get_drvdata(component);
+
+	if (SND_SOC_DAPM_EVENT_OFF(event)) {
+		dev_dbg(nau8821->dev, "system clock control : POWER OFF\n");
+		/* Set clock source to disable or internal clock before the
+		 * playback or capture end. Codec needs clock for Jack
+		 * detection and button press if jack inserted; otherwise,
+		 * the clock should be closed.
+		 */
+		if (nau8821_is_jack_inserted(nau8821->regmap)) {
+			nau8821_configure_sysclk(nau8821,
+				NAU8821_CLK_INTERNAL, 0);
+		} else {
+			nau8821_configure_sysclk(nau8821, NAU8821_CLK_DIS, 0);
+		}
+	}
+	return 0;
+}
+
 static const struct snd_soc_dapm_widget nau8821_dapm_widgets[] = {
+	SND_SOC_DAPM_SUPPLY("System Clock", SND_SOC_NOPM, 0, 0,
+		system_clock_control, SND_SOC_DAPM_POST_PMD),
 	SND_SOC_DAPM_SUPPLY("MICBIAS", NAU8821_R74_MIC_BIAS,
 		NAU8821_MICBIAS_POWERUP_SFT, 0, NULL, 0),
 	SND_SOC_DAPM_SUPPLY("DMIC Clock", SND_SOC_NOPM, 0, 0,
@@ -607,6 +634,9 @@ static const struct snd_soc_dapm_route nau8821_dapm_routes[] = {
 	{"AIFTX", NULL, "ADCL Digital path"},
 	{"AIFTX", NULL, "ADCR Digital path"},
 
+	{"AIFTX", NULL, "System Clock"},
+	{"AIFRX", NULL, "System Clock"},
+
 	{"DDACL", NULL, "AIFRX"},
 	{"DDACR", NULL, "AIFRX"},