ASoC: Introduce snd_soc_of_get_dai_link_cpus

This function is an analogue of snd_soc_of_get_dai_link_codecs to help
machine drivers read CPU DAI lists from devicetrees.
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20220331000449.41062-5-povik+lin@cutebit.orgSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc.h

@@ -1263,6 +1263,10 @@ int snd_soc_of_get_dai_link_codecs(struct device *dev,
 				   struct device_node *of_node,
 				   struct snd_soc_dai_link *dai_link);
 void snd_soc_of_put_dai_link_codecs(struct snd_soc_dai_link *dai_link);
+int snd_soc_of_get_dai_link_cpus(struct device *dev,
+				 struct device_node *of_node,
+				 struct snd_soc_dai_link *dai_link);
+void snd_soc_of_put_dai_link_cpus(struct snd_soc_dai_link *dai_link);
 
 int snd_soc_add_pcm_runtime(struct snd_soc_card *card,
 			    struct snd_soc_dai_link *dai_link);

sound/soc/soc-core.c

@@ -3390,6 +3390,86 @@ int snd_soc_of_get_dai_link_codecs(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(snd_soc_of_get_dai_link_codecs);
 
+/*
+ * snd_soc_of_put_dai_link_cpus - Dereference device nodes in the codecs array
+ * @dai_link: DAI link
+ *
+ * Dereference device nodes acquired by snd_soc_of_get_dai_link_cpus().
+ */
+void snd_soc_of_put_dai_link_cpus(struct snd_soc_dai_link *dai_link)
+{
+	struct snd_soc_dai_link_component *component;
+	int index;
+
+	for_each_link_cpus(dai_link, index, component) {
+		if (!component->of_node)
+			break;
+		of_node_put(component->of_node);
+		component->of_node = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(snd_soc_of_put_dai_link_cpus);
+
+/*
+ * snd_soc_of_get_dai_link_cpus - Parse a list of CPU DAIs in the devicetree
+ * @dev: Card device
+ * @of_node: Device node
+ * @dai_link: DAI link
+ *
+ * Is analogous to snd_soc_of_get_dai_link_codecs but parses a list of CPU DAIs
+ * instead.
+ *
+ * Returns 0 for success
+ */
+int snd_soc_of_get_dai_link_cpus(struct device *dev,
+				 struct device_node *of_node,
+				 struct snd_soc_dai_link *dai_link)
+{
+	struct of_phandle_args args;
+	struct snd_soc_dai_link_component *component;
+	char *name;
+	int index, num_codecs, ret;
+
+	/* Count the number of CODECs */
+	name = "sound-dai";
+	num_codecs = of_count_phandle_with_args(of_node, name,
+						"#sound-dai-cells");
+	if (num_codecs <= 0) {
+		if (num_codecs == -ENOENT)
+			dev_err(dev, "No 'sound-dai' property\n");
+		else
+			dev_err(dev, "Bad phandle in 'sound-dai'\n");
+		return num_codecs;
+	}
+	component = devm_kcalloc(dev,
+				 num_codecs, sizeof(*component),
+				 GFP_KERNEL);
+	if (!component)
+		return -ENOMEM;
+	dai_link->cpus = component;
+	dai_link->num_cpus = num_codecs;
+
+	/* Parse the list */
+	for_each_link_cpus(dai_link, index, component) {
+		ret = of_parse_phandle_with_args(of_node, name,
+						 "#sound-dai-cells",
+						 index, &args);
+		if (ret)
+			goto err;
+		component->of_node = args.np;
+		ret = snd_soc_get_dai_name(&args, &component->dai_name);
+		if (ret < 0)
+			goto err;
+	}
+	return 0;
+err:
+	snd_soc_of_put_dai_link_codecs(dai_link);
+	dai_link->cpus = NULL;
+	dai_link->num_cpus = 0;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(snd_soc_of_get_dai_link_cpus);
+
 static int __init snd_soc_init(void)
 {
 	snd_soc_debugfs_init();