[alsa-devel] [PATCH] ASoC: max98357a: add speaker switch

[Tzung-Bi Shih]

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.

Adds a separate switch to max98357a.  Userspace program has choices to
turn on or off the switch.  Note that, userspace program should change
the switch before opening the stream.  The switch won't take effects if
the stream is already there.

Default value of the switch is on to not break existing driver usages
(who are unlikely aware of existence of the switch).

Signed-off-by: Tzung-Bi Shih <tzungbi at google.com>
---
 sound/soc/codecs/max98357a.c | 39 +++++++++++++++++++++++++++++++++++-
 1 file changed, 38 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/max98357a.c b/sound/soc/codecs/max98357a.c
index 16313b973eaa..a2c3be69a0ee 100644
--- a/sound/soc/codecs/max98357a.c
+++ b/sound/soc/codecs/max98357a.c
@@ -22,6 +22,7 @@
 struct max98357a_priv {
 	struct gpio_desc *sdmode;
 	unsigned int sdmode_delay;
+	int spk_switch;
 };
 
 static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
@@ -29,7 +30,7 @@ static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
 {
 	struct max98357a_priv *max98357a = snd_soc_dai_get_drvdata(dai);
 
-	if (!max98357a->sdmode)
+	if (!max98357a->sdmode || !max98357a->spk_switch)
 		return 0;
 
 	switch (cmd) {
@@ -49,6 +50,37 @@ static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+static int max98357a_get_spk_switch(struct snd_kcontrol *kcontrol,
+		struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component =
+		snd_soc_kcontrol_component(kcontrol);
+	struct max98357a_priv *max98357a =
+		snd_soc_component_get_drvdata(component);
+
+	ucontrol->value.integer.value[0] = max98357a->spk_switch;
+	return 0;
+}
+
+static int max98357a_put_spk_switch(struct snd_kcontrol *kcontrol,
+		struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component =
+		snd_soc_kcontrol_component(kcontrol);
+	struct max98357a_priv *max98357a =
+		snd_soc_component_get_drvdata(component);
+
+	max98357a->spk_switch = ucontrol->value.integer.value[0];
+	dev_info(component->dev,
+		 "put speaker switch: %d\n", max98357a->spk_switch);
+	return 0;
+}
+
+static const struct snd_kcontrol_new max98357a_snd_controls[] = {
+	SOC_SINGLE_BOOL_EXT("Speaker Switch", 0,
+		max98357a_get_spk_switch, max98357a_put_spk_switch),
+};
+
 static const struct snd_soc_dapm_widget max98357a_dapm_widgets[] = {
 	SND_SOC_DAPM_OUTPUT("Speaker"),
 };
@@ -58,6 +90,8 @@ static const struct snd_soc_dapm_route max98357a_dapm_routes[] = {
 };
 
 static const struct snd_soc_component_driver max98357a_component_driver = {
+	.controls		= max98357a_snd_controls,
+	.num_controls		= ARRAY_SIZE(max98357a_snd_controls),
 	.dapm_widgets		= max98357a_dapm_widgets,
 	.num_dapm_widgets	= ARRAY_SIZE(max98357a_dapm_widgets),
 	.dapm_routes		= max98357a_dapm_routes,
@@ -117,6 +151,9 @@ static int max98357a_platform_probe(struct platform_device *pdev)
 			"default: no delay\n");
 	}
 
+	/* For drivers who are not aware of the switch, default set to on. */
+	max98357a->spk_switch = 1;
+
 	dev_set_drvdata(&pdev->dev, max98357a);
 
 	return devm_snd_soc_register_component(&pdev->dev,
-- 
2.25.0.341.g760bfbb309-goog