[DRIVER] add MAX98357A codec support

Add support over I2S for i.MX8 SoCs.
Also, make it possible to use GPIO from expanders to enable the codec.

sound/soc/codecs/max98357a.c

@@ -22,6 +22,7 @@
 
 struct max98357a_priv {
 	struct gpio_desc *sdmode;
+	bool gpio_probe_only;
 	unsigned int sdmode_delay;
 	int sdmode_switch;
 };
@@ -33,7 +34,7 @@ static int max98357a_daiops_trigger(struct snd_pcm_substream *substream,
 	struct max98357a_priv *max98357a =
 		snd_soc_component_get_drvdata(component);
 
-	if (!max98357a->sdmode)
+	if (!max98357a->sdmode || max98357a->gpio_probe_only)
 		return 0;
 
 	switch (cmd) {
@@ -131,8 +132,10 @@ static int max98357a_platform_probe(struct platform_device *pdev)
 	if (!max98357a)
 		return -ENOMEM;
 
-	max98357a->sdmode = devm_gpiod_get_optional(&pdev->dev,
-				"sdmode", GPIOD_OUT_LOW);
+	max98357a->gpio_probe_only = device_property_read_bool(&pdev->dev,
+					"sdmode,gpio-probe-only");
+	max98357a->sdmode = devm_gpiod_get_optional(&pdev->dev, "sdmode",
+			max98357a->gpio_probe_only? GPIOD_OUT_HIGH : GPIOD_OUT_LOW);
 	if (IS_ERR(max98357a->sdmode))
 		return PTR_ERR(max98357a->sdmode);
 

sound/soc/fsl/Kconfig

@@ -317,11 +317,22 @@ config SND_SOC_SECO_TLV320
 	select SND_SOC_TLV320AIC32X4_I2C
 	select SND_SOC_FSL_SAI
 	select SND_SOC_IMX_PCM_DMA
-	select CONFIG_SND_SIMPLE_CARD
+	select SND_SIMPLE_CARD
 	help
 	  Enable I2S based access to the TLV320AIC32x4 codec attached
 	  to the SAI interface
 
+config SND_SOC_SECO_MAX98357A
+	tristate "Seco MAX98357A"
+	depends on OF
+	select SND_SOC_MAX98357A
+	select SND_SIMPLE_CARD
+	select SND_SOC_FSL_SAI
+	select SND_SOC_IMX_PCM_DMA
+	help
+	  Enable I2S based access to the MAX98357A codec attached
+	  to the i.MX8M SAI interface
+
 config SND_SOC_PHYCORE_AC97
 	tristate "SoC Audio support for Phytec phyCORE (and phyCARD) boards"
 	depends on MACH_PCM043 || MACH_PCA100