audioinjector-octo: Add continuous clock feature

By user request, add a switch to prevent the clocks being stopped when
the stream is paused, stopped or shutdown. Provide access to the switch
by adding a 'non-stop-clocks' parameter to the audioinjector-addons
overlay.

See: #2409

Signed-off-by: Phil Elwell <[email protected]>

Author: Phil Elwell

arch/arm/boot/dts/overlays/README

@@ -365,8 +365,9 @@ Params: interrupt               GPIO used for INT (default 23)
 
 Name:   audioinjector-addons
 Info:   Configures the audioinjector.net audio add on soundcards
-Load:   dtoverlay=audioinjector-addons
-Params: <None>
+Load:   dtoverlay=audioinjector-addons,<param>=<val>
+Params: non-stop-clocks         Keeps the clocks running even when the stream
+                                is paused or stopped (default off)
 
 
 Name:   audioinjector-wm8731-audio

arch/arm/boot/dts/overlays/audioinjector-addons-overlay.dts

@@ -42,7 +42,7 @@
 
 	fragment@2 {
 		target = <&sound>;
-		__overlay__ {
+		snd: __overlay__ {
 			compatible = "ai,audioinjector-octo-soundcard";
 			mult-gpios = <&gpio 27 0>, <&gpio 22 0>, <&gpio 23 0>,
 				     <&gpio 24 0>;
@@ -52,4 +52,8 @@
 			status = "okay";
 		};
 	};
+
+	__overrides__ {
+		non-stop-clocks = <&snd>, "non-stop-clocks?";
+	};
 };

sound/soc/bcm/audioinjector-octo-soundcard.c

@@ -29,6 +29,7 @@
 static struct gpio_descs *mult_gpios;
 static struct gpio_desc *codec_rst_gpio;
 static unsigned int audioinjector_octo_rate;
+static bool non_stop_clocks;
 
 static const unsigned int audioinjector_octo_rates[] = {
 	96000, 48000, 32000, 24000, 16000, 8000, 88200, 44100, 29400, 22050, 14700,
@@ -133,12 +134,16 @@ static int audioinjector_octo_hw_params(struct snd_pcm_substream *substream,
 static int audioinjector_octo_trigger(struct snd_pcm_substream *substream,
 								int cmd){
 	int mult[4];
-	mult[0] = 0;
-	mult[1] = 0;
-	mult[2] = 0;
-	mult[3] = 0;
+
+	memset(mult, 0, sizeof(mult));
 
 	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		if (!non_stop_clocks)
+			break;
+		/* Drop through... */
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
@@ -177,10 +182,6 @@ static int audioinjector_octo_trigger(struct snd_pcm_substream *substream,
 			return -EINVAL;
 		}
 		break;
-	case SNDRV_PCM_TRIGGER_STOP:
-	case SNDRV_PCM_TRIGGER_SUSPEND:
-	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
-		break;
 	default:
 		return -EINVAL;
 	}
@@ -276,6 +277,8 @@ static int audioinjector_octo_probe(struct platform_device *pdev)
 		if (IS_ERR(codec_rst_gpio))
 			return PTR_ERR(codec_rst_gpio);
 
+		non_stop_clocks = of_property_read_bool(pdev->dev.of_node, "non-stop-clocks");
+
 		if (codec_rst_gpio)
 			gpiod_set_value(codec_rst_gpio, 1);
 		msleep(500);