ASoC: soc-core: support dai_link with platforms_num != 1

Add support platforms_num != 1 in dai_link. Initially, the main purpose of
this change was to make the platform optional in the dai_link, instead of
inserting the dummy platform driver.

This particular case had just been solved by Kuninori Morimoto with
commit 1d768989 ("ASoC: soc-core: allow no Platform on dai_link").

However, this change may still be useful for those who need multiple
platform components on a single dai_link (it solves one of the FIXME
note in soc-core)
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc.h

@@ -997,6 +997,12 @@ struct snd_soc_dai_link {
 	     ((i) < link->num_codecs) && ((codec) = &link->codecs[i]);	\
 	     (i)++)
 
+#define for_each_link_platforms(link, i, platform)			\
+	for ((i) = 0;							\
+	     ((i) < link->num_platforms) &&				\
+	     ((platform) = &link->platforms[i]);			\
+	     (i)++)
+
 /*
  * Sample 1 : Single CPU/Codec/Platform
  *

sound/soc/soc-core.c

@@ -896,7 +896,7 @@ static int soc_bind_dai_link(struct snd_soc_card *card,
 	struct snd_soc_dai_link *dai_link)
 {
 	struct snd_soc_pcm_runtime *rtd;
-	struct snd_soc_dai_link_component *codecs;
+	struct snd_soc_dai_link_component *codec, *platform;
 	struct snd_soc_component *component;
 	int i;
 
@@ -926,13 +926,14 @@ static int soc_bind_dai_link(struct snd_soc_card *card,
 
 	/* Find CODEC from registered CODECs */
 	rtd->num_codecs = dai_link->num_codecs;
-	for_each_link_codecs(dai_link, i, codecs) {
-		rtd->codec_dais[i] = snd_soc_find_dai(codecs);
+	for_each_link_codecs(dai_link, i, codec) {
+		rtd->codec_dais[i] = snd_soc_find_dai(codec);
 		if (!rtd->codec_dais[i]) {
 			dev_info(card->dev, "ASoC: CODEC DAI %s not registered\n",
-				 codecs->dai_name);
+				 codec->dai_name);
 			goto _err_defer;
 		}
+
 		snd_soc_rtdcom_add(rtd, rtd->codec_dais[i]->component);
 	}
 
@@ -940,12 +941,13 @@ static int soc_bind_dai_link(struct snd_soc_card *card,
 	rtd->codec_dai = rtd->codec_dais[0];
 
 	/* Find PLATFORM from registered PLATFORMs */
-	for_each_component(component) {
-		if (!snd_soc_is_matching_component(dai_link->platforms,
-						   component))
-			continue;
+	for_each_link_platforms(dai_link, i, platform) {
+		for_each_component(component) {
+			if (!snd_soc_is_matching_component(platform, component))
+				continue;
 
-		snd_soc_rtdcom_add(rtd, component);
+			snd_soc_rtdcom_add(rtd, component);
+		}
 	}
 
 	soc_add_pcm_runtime(card, rtd);
@@ -1058,15 +1060,14 @@ static int soc_init_dai_link(struct snd_soc_card *card,
 			     struct snd_soc_dai_link *link)
 {
 	int i;
-	struct snd_soc_dai_link_component *codec;
+	struct snd_soc_dai_link_component *codec, *platform;
 
 	for_each_link_codecs(link, i, codec) {
 		/*
 		 * Codec must be specified by 1 of name or OF node,
 		 * not both or neither.
 		 */
-		if (!!codec->name ==
-		    !!codec->of_node) {
+		if (!!codec->name == !!codec->of_node) {
 			dev_err(card->dev, "ASoC: Neither/both codec name/of_node are set for %s\n",
 				link->name);
 			return -EINVAL;
@@ -1087,36 +1088,24 @@ static int soc_init_dai_link(struct snd_soc_card *card,
 			return -EPROBE_DEFER;
 	}
 
-	/*
-	 * Platform may be specified by either name or OF node,
-	 * or no Platform.
-	 *
-	 * FIXME
-	 *
-	 * We need multi-platform support
-	 */
-	if (link->num_platforms > 0) {
-
-		if (link->num_platforms > 1) {
-			dev_err(card->dev,
-				"ASoC: multi platform is not yet supported %s\n",
-				link->name);
-			return -EINVAL;
-		}
-
-		if (link->platforms->name && link->platforms->of_node) {
+	for_each_link_platforms(link, i, platform) {
+		/*
+		 * Platform may be specified by either name or OF node, but it
+		 * can be left unspecified, then no components will be inserted
+		 * in the rtdcom list
+		 */
+		if (!!platform->name == !!platform->of_node) {
 			dev_err(card->dev,
-				"ASoC: Both platform name/of_node are set for %s\n",
+				"ASoC: Neither/both platform name/of_node are set for %s\n",
 				link->name);
 			return -EINVAL;
 		}
 
 		/*
-		 * Defer card registartion if platform dai component is not
-		 * added to component list.
+		 * Defer card registration if platform component is not added to
+		 * component list.
 		 */
-		if ((link->platforms->of_node || link->platforms->name) &&
-		    !soc_find_component(link->platforms))
+		if (!soc_find_component(platform))
 			return -EPROBE_DEFER;
 	}