ASoC: max98357a: move control of SD_MODE to DAPM

Some machine may share the same I2S lines for multiple codecs. For
example, mediatek/mt8183/mt8183-da7219-max98357 shares the same lines
between max98357a and da7219.  When writing audio data through the I2S
lines, all codecs on the lines would try to generate sound if they
accepts DO line.  As a result, multiple codecs generate sound at a
time.

Moves control of SD_MODE to DAPM so that machine drivers have chances
to manipulate DAPM widget to turn on/off max98357a.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200212124608.1.I73b26b5e319de173d05823e79f5861bf1826261c@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/max98357a.c

@@ -5,6 +5,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/gpio.h>
@@ -24,26 +25,24 @@ struct max98357a_priv {
 	unsigned int sdmode_delay;
 };
 
-static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
-		int cmd, struct snd_soc_dai *dai)
+static int max98357a_sdmode_event(struct snd_soc_dapm_widget *w,
+		struct snd_kcontrol *kcontrol, int event)
 {
-	struct max98357a_priv *max98357a = snd_soc_dai_get_drvdata(dai);
+	struct snd_soc_component *component =
+		snd_soc_dapm_to_component(w->dapm);
+	struct max98357a_priv *max98357a =
+		snd_soc_component_get_drvdata(component);
 
 	if (!max98357a->sdmode)
 		return 0;
 
-	switch (cmd) {
-	case SNDRV_PCM_TRIGGER_START:
-	case SNDRV_PCM_TRIGGER_RESUME:
-	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-		mdelay(max98357a->sdmode_delay);
+	if (event & SND_SOC_DAPM_POST_PMU) {
+		msleep(max98357a->sdmode_delay);
 		gpiod_set_value(max98357a->sdmode, 1);
-		break;
-	case SNDRV_PCM_TRIGGER_STOP:
-	case SNDRV_PCM_TRIGGER_SUSPEND:
-	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		dev_dbg(component->dev, "set sdmode to 1");
+	} else if (event & SND_SOC_DAPM_PRE_PMD) {
 		gpiod_set_value(max98357a->sdmode, 0);
-		break;
+		dev_dbg(component->dev, "set sdmode to 0");
 	}
 
 	return 0;
@@ -51,10 +50,14 @@ static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
 
 static const struct snd_soc_dapm_widget max98357a_dapm_widgets[] = {
 	SND_SOC_DAPM_OUTPUT("Speaker"),
+	SND_SOC_DAPM_OUT_DRV_E("SD_MODE", SND_SOC_NOPM, 0, 0, NULL, 0,
+			max98357a_sdmode_event,
+			SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_PRE_PMD),
 };
 
 static const struct snd_soc_dapm_route max98357a_dapm_routes[] = {
-	{"Speaker", NULL, "HiFi Playback"},
+	{"SD_MODE", NULL, "HiFi Playback"},
+	{"Speaker", NULL, "SD_MODE"},
 };
 
 static const struct snd_soc_component_driver max98357a_component_driver = {
@@ -68,10 +71,6 @@ static const struct snd_soc_component_driver max98357a_component_driver = {
 	.non_legacy_dai_naming	= 1,
 };
 
-static const struct snd_soc_dai_ops max98357a_dai_ops = {
-	.trigger	= max98357a_daiops_trigger,
-};
-
 static struct snd_soc_dai_driver max98357a_dai_driver = {
 	.name = "HiFi",
 	.playback = {
@@ -91,7 +90,6 @@ static struct snd_soc_dai_driver max98357a_dai_driver = {
 		.channels_min	= 1,
 		.channels_max	= 2,
 	},
-	.ops    = &max98357a_dai_ops,
 };
 
 static int max98357a_platform_probe(struct platform_device *pdev)