ASoC: audio-graph-card2: Introduce playback-only/capture-only DAI link flags

We need this to support MICFIL PDM found on i.MX8MP where the DAI link
supports only capture direction.

Signed-off-by: Daniel Baluta <[e-mail]>
Link: https://msgid.link/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/sound/simple_card_utils.h

···
 int graph_util_parse_dai(struct device *dev, struct device_node *ep,
 			 struct snd_soc_dai_link_component *dlc, int *is_single_link);
 
+int graph_util_parse_link_direction(struct device_node *np,
+				    bool *is_playback_only, bool *is_capture_only);
+
 #ifdef DEBUG
 static inline void simple_util_debug_dai(struct simple_util_priv *priv,
 					 char *name,

sound/soc/generic/audio-graph-card2.c

···
 	struct device_node *ep;
 	struct device_node *ports;
 	unsigned int daifmt = 0, daiclk = 0;
+	bool playback_only = 0, capture_only = 0;
 	unsigned int bit_frame = 0;
 
 	if (graph_lnk_is_multi(port)) {
···
 	daiclk = snd_soc_daifmt_clock_provider_from_bitmap(bit_frame);
 	if (is_cpu_node)
 		daiclk = snd_soc_daifmt_clock_provider_flipped(daiclk);
+
+	graph_util_parse_link_direction(port, &playback_only, &capture_only);
+
+	dai_link->playback_only = playback_only;
+	dai_link->capture_only = capture_only;
 
 	dai_link->dai_fmt	= daifmt | daiclk;
 	dai_link->init		= simple_util_dai_init;

sound/soc/generic/simple-card-utils.c

···
 }
 EXPORT_SYMBOL_GPL(graph_util_parse_dai);
 
+int graph_util_parse_link_direction(struct device_node *np,
+				    bool *playback_only, bool *capture_only)
+{
+	bool is_playback_only = false;
+	bool is_capture_only = false;
+
+	is_playback_only = of_property_read_bool(np, "playback-only");
+	is_capture_only = of_property_read_bool(np, "capture-only");
+
+	if (is_playback_only && is_capture_only)
+		return -EINVAL;
+
+	*playback_only = is_playback_only;
+	*capture_only = is_capture_only;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(graph_util_parse_link_direction);
+
 /* Module information */
 MODULE_AUTHOR("Kuninori Morimoto <[e-mail]>");
 MODULE_DESCRIPTION("ALSA SoC Simple Card Utils");