[PATCH v10 9/9] ASoC: add generic dt-card support

[Jean-Francois Moine <moinejf@free.fr>]

To create simple cards, the syntax of the simple-card does not follow
the common binding of the device graphs
(Documentation/devicetree/bindings/graph.txt).

dt-card devices are created by audio controllers with themselves as the
root of the graph. The sound card is created according to the parameters
found in the tree.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
---
 sound/soc/generic/Kconfig   |   2 +
 sound/soc/generic/Makefile  |   2 +
 sound/soc/generic/dt-card.c | 275 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 279 insertions(+)
 create mode 100644 sound/soc/generic/dt-card.c

diff --git a/sound/soc/generic/Kconfig b/sound/soc/generic/Kconfig
index 610f612..9c5e1e2 100644
--- a/sound/soc/generic/Kconfig
+++ b/sound/soc/generic/Kconfig
@@ -2,3 +2,5 @@ config SND_SIMPLE_CARD
 	tristate "ASoC Simple sound card support"
 	help
 	  This option enables generic simple sound card support
+config SND_DT_CARD
+	tristate
diff --git a/sound/soc/generic/Makefile b/sound/soc/generic/Makefile
index 9c3b246..56834a9 100644
--- a/sound/soc/generic/Makefile
+++ b/sound/soc/generic/Makefile
@@ -1,3 +1,5 @@
 snd-soc-simple-card-objs	:= simple-card.o
+snd-soc-dt-card-objs		:= dt-card.o
 
 obj-$(CONFIG_SND_SIMPLE_CARD)	+= snd-soc-simple-card.o
+obj-$(CONFIG_SND_DT_CARD)	+= snd-soc-dt-card.o
diff --git a/sound/soc/generic/dt-card.c b/sound/soc/generic/dt-card.c
new file mode 100644
index 0000000..6a5de2f
--- /dev/null
+++ b/sound/soc/generic/dt-card.c
@@ -0,0 +1,275 @@
+/*
+ * ALSA SoC DT based sound card support
+ *
+ * Copyright (C) 2015 Jean-Francois Moine
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <sound/soc.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* check if a node is an audio port */
+static int asoc_dt_card_is_audio_port(struct device_node *of_port)
+{
+	const char *name;
+	int ret;
+
+	if (!of_port->name ||
+	    of_node_cmp(of_port->name, "port") != 0)
+		return 0;
+	ret = of_property_read_string(of_port,
+					"port-type",
+					&name);
+	if (!ret &&
+	    (strcmp(name, "i2s") == 0 ||
+	     strcmp(name, "spdif") == 0))
+		return 1;
+	return 0;
+}
+
+/*
+ * Get the DAI number from the DT by counting the audio ports
+ * of the remote device node (codec).
+ */
+static int asoc_dt_card_get_dai_number(struct device_node *of_codec,
+				struct device_node *of_remote_endpoint)
+{
+	struct device_node *of_port, *of_endpoint;
+	int ndai;
+
+	ndai = 0;
+	for_each_child_of_node(of_codec, of_port) {
+		if (!asoc_dt_card_is_audio_port(of_port))
+			continue;
+		for_each_child_of_node(of_port, of_endpoint) {
+			if (!of_endpoint->name ||
+			    of_node_cmp(of_endpoint->name, "endpoint") != 0)
+				continue;
+			if (of_endpoint == of_remote_endpoint) {
+				of_node_put(of_port);
+				of_node_put(of_endpoint);
+				return ndai;
+			}
+		}
+		ndai++;
+	}
+	return 0;		/* should never be reached */
+}
+
+/*
+ * Parse a graph of audio ports
+ * @dev: Card device
+ * @of_cpu: Device node of the audio controller
+ * @card: Card definition
+ *
+ * Builds the DAI links of the card from the DT graph of audio ports
+ * starting from the audio controller.
+ * It does not handle the port groups.
+ * The CODEC device nodes in the DAI links must be dereferenced by the caller.
+ *
+ * Returns the number of DAI links or (< 0) on error
+ */
+static int asoc_dt_card_of_parse_graph(struct device *dev,
+				struct device_node *of_cpu,
+				struct snd_soc_card *card)
+{
+	struct device_node *of_codec, *of_port, *of_endpoint,
+				*of_remote_endpoint;
+	struct snd_soc_dai_link *link;
+	struct snd_soc_dai_link_component *component;
+	struct of_phandle_args args, args2;
+	int ret, ilink, icodec, nlinks, ncodecs;
+
+	/* count the number of DAI links */
+	nlinks = 0;
+	for_each_child_of_node(of_cpu, of_port) {
+		if (asoc_dt_card_is_audio_port(of_port))
+			nlinks++;
+	}
+
+	/* allocate the DAI link array */
+	link = devm_kzalloc(dev, sizeof(*link) * nlinks, GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+	card->dai_link = link;
+
+	/* build the DAI links */
+	ilink = 0;
+	args.np = of_cpu;
+	args.args_count = 1;
+	for_each_child_of_node(of_cpu, of_port) {
+		if (!asoc_dt_card_is_audio_port(of_port))
+			continue;
+
+		link->platform_of_node =
+			link->cpu_of_node = of_cpu;
+		args.args[0] = ilink;
+		ret = snd_soc_get_dai_name(&args, &link->cpu_dai_name);
+		if (ret) {
+			dev_err(dev, "no CPU DAI name for link %d!\n",
+				ilink);
+			continue;
+		}
+
+		/* count the number of codecs of this DAI link */
+		ncodecs = 0;
+		for_each_child_of_node(of_port, of_endpoint) {
+			if (of_parse_phandle(of_endpoint,
+					"remote-endpoint", 0))
+				ncodecs++;
+		}
+		if (ncodecs == 0)
+			continue;
+		component = devm_kzalloc(dev,
+					 sizeof(*component) * ncodecs,
+					 GFP_KERNEL);
+		if (!component)
+			return -ENOMEM;
+		link->codecs = component;
+
+		icodec = 0;
+		args2.args_count = 1;
+		for_each_child_of_node(of_port, of_endpoint) {
+			of_remote_endpoint = of_parse_phandle(of_endpoint,
+						"remote-endpoint", 0);
+			if (!of_remote_endpoint)
+				continue;
+			component->of_node = of_codec =
+					of_remote_endpoint->parent->parent;
+			args2.np = of_codec;
+			args2.args[0] = asoc_dt_card_get_dai_number(of_codec,
+							of_remote_endpoint);
+			ret = snd_soc_get_dai_name(&args2,
+						   &component->dai_name);
+			if (ret) {
+				if (ret == -EPROBE_DEFER) {
+					card->num_links = ilink + 1;
+					link->num_codecs = icodec;
+					return ret;
+				}
+				dev_err(dev,
+					"no CODEC DAI name for link %d\n",
+					ilink);
+				continue;
+			}
+			of_node_get(of_codec);
+
+			icodec++;
+			if (icodec >= ncodecs)
+				break;
+			component++;
+		}
+		if (icodec == 0)
+			continue;
+		link->num_codecs = icodec;
+
+		ilink++;
+		if (ilink >= nlinks)
+			break;
+		link++;
+	}
+	card->num_links = ilink;
+
+	return ilink;
+}
+
+static void asoc_dt_card_unref(struct platform_device *pdev)
+{
+	struct snd_soc_card *card = platform_get_drvdata(pdev);
+	struct snd_soc_dai_link *link;
+	int nlinks, ncodecs;
+
+	if (card) {
+		for (nlinks = 0, link = card->dai_link;
+		     nlinks < card->num_links;
+		     nlinks++, link++) {
+			for (ncodecs = 0;
+			     ncodecs < link->num_codecs;
+			     ncodecs++)
+				of_node_put(card->dai_link->codecs[ncodecs].of_node);
+		}
+	}
+}
+
+/*
+ * The platform data contains the pointer to the device node
+ * which starts the description of the graph of the audio ports,
+ * This device node is usually the audio controller.
+ */
+static int asoc_dt_card_probe(struct platform_device *pdev)
+{
+	struct device_node **p_np = pdev->dev.platform_data;
+	struct device_node *of_cpu = *p_np;
+	struct snd_soc_card *card;
+	struct snd_soc_dai_link *link;
+	char *name;
+	int ret, i;
+
+	card = devm_kzalloc(&pdev->dev, sizeof(*card), GFP_KERNEL);
+	if (!card)
+		return -ENOMEM;
+	ret = asoc_dt_card_of_parse_graph(&pdev->dev, of_cpu, card);
+	if (ret < 0)
+		goto err;
+
+	/* fill the remaining values of the card */
+	card->owner = THIS_MODULE;
+	card->dev = &pdev->dev;
+	card->name = "DT-card";
+	for (i = 0, link = card->dai_link;
+	     i < card->num_links;
+	     i++, link++) {
+		name = devm_kzalloc(&pdev->dev,
+				strlen(link->cpu_dai_name) +
+					strlen(link->codecs[0].dai_name) +
+					2,
+				GFP_KERNEL);
+		if (!name) {
+			ret = -ENOMEM;
+			goto err;
+		}
+		sprintf(name, "%s-%s", link->cpu_dai_name,
+					link->codecs[0].dai_name);
+		link->name = link->stream_name = name;
+	}
+
+	card->dai_link->dai_fmt =
+		snd_soc_of_parse_daifmt(of_cpu, "dt-audio-card,",
+					NULL, NULL) &
+			~SND_SOC_DAIFMT_MASTER_MASK;
+
+	ret = devm_snd_soc_register_card(&pdev->dev, card);
+	if (ret >= 0)
+		return ret;
+
+err:
+	asoc_dt_card_unref(pdev);
+	return ret;
+}
+
+static int asoc_dt_card_remove(struct platform_device *pdev)
+{
+	asoc_dt_card_unref(pdev);
+	snd_soc_unregister_card(platform_get_drvdata(pdev));
+	return 0;
+}
+
+static struct platform_driver asoc_dt_card = {
+	.driver = {
+		.name = "asoc-dt-card",
+	},
+	.probe = asoc_dt_card_probe,
+	.remove = asoc_dt_card_remove,
+};
+
+module_platform_driver(asoc_dt_card);
+
+MODULE_ALIAS("platform:asoc-dt-card");
+MODULE_DESCRIPTION("ASoC DT Sound Card");
+MODULE_AUTHOR("Jean-Francois Moine <moinejf@free.fr>");
+MODULE_LICENSE("GPL");
-- 
2.1.4