ASoC: SOF: ipc4-topology: Advertise passthrough capable PCMs (using ChainDMA)

If a PCM is set to use ChainDMA then add it to the card->components string
after a marker of iec61937-pcm:, for example on current HDA platforms where
HDMI is set to use ChainDMA:
iec61937-pcm:5,4,3 (the order of the PCM ids can differ)

UCM is expected to parse and use this property to allow applications to
use bytestream passthrough in a standard way.
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20240426153902.39560-6-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/ipc4-topology.c

@@ -407,6 +407,52 @@ static void sof_ipc4_widget_update_kcontrol_module_id(struct snd_sof_widget *swi
 	}
 }
 
+static int
+sof_ipc4_update_card_components_string(struct snd_sof_widget *swidget,
+				       struct snd_sof_pcm *spcm, int dir)
+{
+	struct snd_sof_widget *pipe_widget = swidget->spipe->pipe_widget;
+	struct sof_ipc4_pipeline *pipeline = pipe_widget->private;
+	struct snd_soc_component *scomp = spcm->scomp;
+	struct snd_soc_card *card = scomp->card;
+	const char *pt_marker = "iec61937-pcm";
+
+	/*
+	 * Update the card's components list with iec61937-pcm and a list of PCM
+	 * ids where ChainDMA is enabled.
+	 * These PCMs can be used for bytestream passthrough.
+	 */
+	if (!pipeline->use_chain_dma)
+		return 0;
+
+	if (card->components) {
+		const char *tmp = card->components;
+
+		if (strstr(card->components, pt_marker))
+			card->components = devm_kasprintf(card->dev, GFP_KERNEL,
+							  "%s,%d",
+							  card->components,
+							  spcm->pcm.pcm_id);
+		else
+			card->components = devm_kasprintf(card->dev, GFP_KERNEL,
+							  "%s %s:%d",
+							  card->components,
+							  pt_marker,
+							  spcm->pcm.pcm_id);
+
+		devm_kfree(card->dev, tmp);
+	} else {
+		card->components = devm_kasprintf(card->dev, GFP_KERNEL,
+						  "%s:%d", pt_marker,
+						  spcm->pcm.pcm_id);
+	}
+
+	if (!card->components)
+		return -ENOMEM;
+
+	return 0;
+}
+
 static int sof_ipc4_widget_setup_pcm(struct snd_sof_widget *swidget)
 {
 	struct sof_ipc4_available_audio_format *available_fmt;
@@ -452,6 +498,10 @@ static int sof_ipc4_widget_setup_pcm(struct snd_sof_widget *swidget)
 	if (!spcm)
 		goto skip_gtw_cfg;
 
+	ret = sof_ipc4_update_card_components_string(swidget, spcm, dir);
+	if (ret)
+		goto free_available_fmt;
+
 	if (dir == SNDRV_PCM_STREAM_PLAYBACK) {
 		struct snd_sof_pcm_stream *sps = &spcm->stream[dir];