ASoC: soc-dai: add snd_soc_dai_prepare()

Current ALSA SoC is directly using dai->driver->ops->xxx,
thus, it has deep nested bracket, and it makes code unreadable.
This patch adds new snd_soc_dai_prepare() and use it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87tvbehn46.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dai.h

@@ -154,6 +154,8 @@ int snd_soc_dai_startup(struct snd_soc_dai *dai,
 			struct snd_pcm_substream *substream);
 void snd_soc_dai_shutdown(struct snd_soc_dai *dai,
 			  struct snd_pcm_substream *substream);
+int snd_soc_dai_prepare(struct snd_soc_dai *dai,
+			struct snd_pcm_substream *substream);
 
 struct snd_soc_dai_ops {
 	/*

sound/soc/soc-dai.c

@@ -307,3 +307,14 @@ void snd_soc_dai_shutdown(struct snd_soc_dai *dai,
 	if (dai->driver->ops->shutdown)
 		dai->driver->ops->shutdown(substream, dai);
 }
+
+int snd_soc_dai_prepare(struct snd_soc_dai *dai,
+			struct snd_pcm_substream *substream)
+{
+	int ret = 0;
+
+	if (dai->driver->ops->prepare)
+		ret = dai->driver->ops->prepare(substream, dai);
+
+	return ret;
+}

sound/soc/soc-pcm.c

@@ -814,9 +814,7 @@ static int soc_pcm_prepare(struct snd_pcm_substream *substream)
 	}
 
 	for_each_rtd_codec_dai(rtd, i, codec_dai) {
-		if (codec_dai->driver->ops->prepare) {
-			ret = codec_dai->driver->ops->prepare(substream,
-							      codec_dai);
+		ret = snd_soc_dai_prepare(codec_dai, substream);
 		if (ret < 0) {
 			dev_err(codec_dai->dev,
 				"ASoC: codec DAI prepare error: %d\n",
@@ -824,16 +822,13 @@ static int soc_pcm_prepare(struct snd_pcm_substream *substream)
 			goto out;
 		}
 	}
-	}
 
-	if (cpu_dai->driver->ops->prepare) {
-		ret = cpu_dai->driver->ops->prepare(substream, cpu_dai);
+	ret = snd_soc_dai_prepare(cpu_dai, substream);
 	if (ret < 0) {
 		dev_err(cpu_dai->dev,
 			"ASoC: cpu DAI prepare error: %d\n", ret);
 		goto out;
 	}
-	}
 
 	/* cancel any delayed stream shutdown that is pending */
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&