Add support for IIO devices in ASoC

Merge series from Herve Codina <herve.codina@bootlin.com>:

Several weeks ago, I sent a series [1] for adding a potentiometer as an
auxiliary device in ASoC. The feedback was that the potentiometer should
be directly handled in IIO (as other potentiometers) and something more
generic should be present in ASoC in order to have a binding to import
some IIO devices into sound cards.

The series related to the IIO potentiometer device is already applied.

This series introduces audio-iio-aux. Its goal is to offer the binding
between IIO and ASoC.
It exposes attached IIO devices as ASoC auxiliary devices and allows to
control them through mixer controls.

On my system, the IIO device is a potentiometer and it is present in an
amplifier design present in the audio path.

1 files changed, 44 insertions, 2 deletions

diff --git a/sound/soc/generic/simple-card.c b/sound/soc/generic/simple-card.c
index 0745bf6a09aa..a78babf44f38 100644
--- a/sound/soc/generic/simple-card.c
+++ b/sound/soc/generic/simple-card.c
@@ -346,6 +346,7 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
 	struct device *dev = simple_priv_to_dev(priv);
 	struct device_node *top = dev->of_node;
 	struct device_node *node;
+	struct device_node *add_devs;
 	uintptr_t dpcm_selectable = (uintptr_t)of_device_get_match_data(dev);
 	bool is_top = 0;
 	int ret = 0;
@@ -357,6 +358,8 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
 		is_top = 1;
 	}
 
+	add_devs = of_get_child_by_name(top, PREFIX "additional-devs");
+
 	/* loop for all dai-link */
 	do {
 		struct asoc_simple_data adata;
@@ -365,6 +368,12 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
 		struct device_node *np;
 		int num = of_get_child_count(node);
 
+		/* Skip additional-devs node */
+		if (node == add_devs) {
+			node = of_get_next_child(top, node);
+			continue;
+		}
+
 		/* get codec */
 		codec = of_get_child_by_name(node, is_top ?
 					     PREFIX "codec" : "codec");
@@ -378,12 +387,15 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
 
 		/* get convert-xxx property */
 		memset(&adata, 0, sizeof(adata));
-		for_each_child_of_node(node, np)
+		for_each_child_of_node(node, np) {
+			if (np == add_devs)
+				continue;
 			simple_parse_convert(dev, np, &adata);
+		}
 
 		/* loop for all CPU/Codec node */
 		for_each_child_of_node(node, np) {
-			if (plat == np)
+			if (plat == np || add_devs == np)
 				continue;
 			/*
 			 * It is DPCM
@@ -426,6 +438,7 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
 	} while (!is_top && node);
 
  error:
+	of_node_put(add_devs);
 	of_node_put(node);
 	return ret;
 }
@@ -463,6 +476,31 @@ static int simple_for_each_link(struct asoc_simple_priv *priv,
 	return ret;
 }
 
+static void simple_depopulate_aux(void *data)
+{
+	struct asoc_simple_priv *priv = data;
+
+	of_platform_depopulate(simple_priv_to_dev(priv));
+}
+
+static int simple_populate_aux(struct asoc_simple_priv *priv)
+{
+	struct device *dev = simple_priv_to_dev(priv);
+	struct device_node *node;
+	int ret;
+
+	node = of_get_child_by_name(dev->of_node, PREFIX "additional-devs");
+	if (!node)
+		return 0;
+
+	ret = of_platform_populate(node, NULL, NULL, dev);
+	of_node_put(node);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, simple_depopulate_aux, priv);
+}
+
 static int simple_parse_of(struct asoc_simple_priv *priv, struct link_info *li)
 {
 	struct snd_soc_card *card = simple_priv_to_card(priv);
@@ -492,6 +530,10 @@ static int simple_parse_of(struct asoc_simple_priv *priv, struct link_info *li)
 	if (ret < 0)
 		return ret;
 
+	ret = simple_populate_aux(priv);
+	if (ret < 0)
+		return ret;
+
 	ret = snd_soc_of_parse_aux_devs(card, PREFIX "aux-devs");
 
 	return ret;