ASoC: audio-graph-card2: add Codec2Codec support

This patch adds Codec2Codec support to audio-graph-card2.
It can use Codec2Codec but very simple case only for now.
It doesn't have "SWITCH" control yet, thus it start automatically
when it was probed, and can't stop, so far.
Thus it needs to be updated around widgets/routing handling,
and you need to understand that it is under experimental.

Codec has SND_SOC_DAPM_INPUT() (= IN) / SND_SOC_DAPM_OUTPUT(= OUT)
widgets in below case.

It is assuming 2channel, S32_LE format for now.
It needs to be updated, too.

It needs "codec2codec" node (= B), needs to have routing (= A),
need to indicate CPU side at links (= X).
ports@0 is for CPU side (= X), port@1 is Codec side (= Y).
It needs to have "rate" (= C)

+--+
| |<-- Codec0 <-- IN
| |--> Codec1 --> OUT
+--+

sound {
compatible = "audio-graph-card2";

(A) routing = "OUT" ,"DAI1 Playback",
"DAI0 Capture", "IN";

(X) links = <&c2c>;

(B) codec2codec {
ports {
(C) rate = <48000>;
(X) c2c: port@0 { c2cf_ep: endpoint { remote-endpoint = <&codec0_ep>; }; };
(Y) port@1 { c2cb_ep: endpoint { remote-endpoint = <&codec1_ep>; }; };
};
};

Codec {
ports {
port@0 {
bitclock-master;
frame-master;
codec0_ep: endpoint { remote-endpoint = <&c2cf_ep>; }; };
port@1 { codec1_ep: endpoint { remote-endpoint = <&c2cb_ep>; }; };
};
};

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Kuninori Morimoto <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/sound/graph_card.h

···
 	int (*hook_post)(struct asoc_simple_priv *priv);
 	GRAPH2_CUSTOM custom_normal;
 	GRAPH2_CUSTOM custom_dpcm;
+	GRAPH2_CUSTOM custom_c2c;
 };
 
 int audio_graph_parse_of(struct asoc_simple_priv *priv, struct device *dev);
···
 			     struct device_node *lnk, struct link_info *li);
 int audio_graph2_link_dpcm(struct asoc_simple_priv *priv,
 			   struct device_node *lnk, struct link_info *li);
+int audio_graph2_link_c2c(struct asoc_simple_priv *priv,
+			  struct device_node *lnk, struct link_info *li);
 
 #endif /* __GRAPH_CARD_H */

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

···
 	};
  };
 
+ ************************************
+	Codec to Codec
+ ************************************
+
+ +--+
+ |  |<-- Codec0 <- IN
+ |  |--> Codec1 -> OUT
+ +--+
+
+ sound {
+	compatible = "audio-graph-card2";
+
+	routing = "OUT" ,"DAI1 Playback",
+		  "DAI0 Capture", "IN";
+
+	links = <&c2c>;
+
+	codec2codec {
+		ports {
+			rate = <48000>;
+		c2c:	port@0 { c2cf_ep: endpoint { remote-endpoint = <&codec0_ep>; }; };
+			port@1 { c2cb_ep: endpoint { remote-endpoint = <&codec1_ep>; }; };
+	};
+ };
+
+ Codec {
+	ports {
+		port@0 {
+			bitclock-master;
+			frame-master;
+			 codec0_ep: endpoint { remote-endpoint = <&c2cf_ep>; }; };
+		port@1 { codec1_ep: endpoint { remote-endpoint = <&c2cb_ep>; }; };
+	};
+ };
+
 */
 
 enum graph_type {
 	GRAPH_NORMAL,
 	GRAPH_DPCM,
+	GRAPH_C2C,
 
 	GRAPH_MULTI,	/* don't use ! Use this only in __graph_get_type() */
 };
 
 #define GRAPH_NODENAME_MULTI	"multi"
 #define GRAPH_NODENAME_DPCM	"dpcm"
+#define GRAPH_NODENAME_C2C	"codec2codec"
 
 #define port_to_endpoint(port) of_get_child_by_name(port, "endpoint")
 
···
 	if (of_node_name_eq(np, GRAPH_NODENAME_DPCM))
 		return GRAPH_DPCM;
 
+	if (of_node_name_eq(np, GRAPH_NODENAME_C2C))
+		return GRAPH_C2C;
+
 	return GRAPH_NORMAL;
 }
 
···
 				str = "DPCM Front-End";
 			else
 				str = "DPCM Back-End";
+			break;
+		case GRAPH_C2C:
+			str = "Codec2Codec";
 			break;
 		default:
 			break;
···
 			else
 				asoc_simple_set_dailink_name(dev, dai_link, "be.%pOFP.%s%s",
 						codecs->of_node, codecs->dai_name, codec_multi);
+			break;
+		case GRAPH_C2C:
+			/* run is_cpu only. see audio_graph2_link_c2c() */
+			if (is_cpu)
+				asoc_simple_set_dailink_name(dev, dai_link, "c2c.%s%s-%s%s",
+							     cpus->dai_name,   cpu_multi,
+							     codecs->dai_name, codec_multi);
 			break;
 		default:
 			break;
···
 }
 EXPORT_SYMBOL_GPL(audio_graph2_link_dpcm);
 
+int audio_graph2_link_c2c(struct asoc_simple_priv *priv,
+			  struct device_node *lnk,
+			  struct link_info *li)
+{
+	struct snd_soc_dai_link *dai_link = simple_priv_to_link(priv, li->link);
+	struct simple_dai_props *dai_props = simple_priv_to_props(priv, li->link);
+	struct snd_soc_pcm_stream *c2c_conf = dai_props->c2c_conf;
+	struct device_node *port0, *port1, *ports;
+	struct device_node *codec0_port, *codec1_port;
+	struct device_node *ep0, *ep1;
+	u32 val;
+	int ret = -EINVAL;
+
+	/*
+	 * codec2codec {
+	 *	ports {
+	 *		rate = <48000>;
+	 * =>	lnk:	port@0 { c2c0_ep: { ... = codec0_ep; }; };
+	 *		port@1 { c2c1_ep: { ... = codec1_ep; }; };
+	 *	};
+	 * };
+	 *
+	 * Codec {
+	 *	ports {
+	 *		port@0 { codec0_ep: ... }; };
+	 *		port@1 { codec1_ep: ... }; };
+	 *	};
+	 * };
+	 */
+	of_node_get(lnk);
+	port0 = lnk;
+	ports = of_get_parent(port0);
+	port1 = of_get_next_child(ports, lnk);
+
+	if (!of_get_property(ports, "rate", &val)) {
+		struct device *dev = simple_priv_to_dev(priv);
+
+		dev_err(dev, "Codec2Codec needs rate settings\n");
+		goto err1;
+	}
+
+	c2c_conf->formats	= SNDRV_PCM_FMTBIT_S32_LE; /* update ME */
+	c2c_conf->rate_min	=
+	c2c_conf->rate_max	= val;
+	c2c_conf->channels_min	=
+	c2c_conf->channels_max	= 2; /* update ME */
+	dai_link->params	= c2c_conf;
+
+	ep0 = port_to_endpoint(port0);
+	ep1 = port_to_endpoint(port1);
+
+	codec0_port = of_graph_get_remote_port(ep0);
+	codec1_port = of_graph_get_remote_port(ep1);
+
+	/*
+	 * call Codec first.
+	 * see
+	 *	__graph_parse_node() :: DAI Naming
+	 */
+	ret = graph_parse_node(priv, GRAPH_C2C, codec1_port, li, 0);
+	if (ret < 0)
+		goto err2;
+
+	/*
+	 * call CPU, and set DAI Name
+	 */
+	ret = graph_parse_node(priv, GRAPH_C2C, codec0_port, li, 1);
+	if (ret < 0)
+		goto err2;
+
+	graph_link_init(priv, codec0_port, li, 1);
+err2:
+	of_node_put(ep0);
+	of_node_put(ep1);
+	of_node_put(codec0_port);
+	of_node_put(codec1_port);
+err1:
+	of_node_put(ports);
+	of_node_put(port0);
+	of_node_put(port1);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(audio_graph2_link_c2c);
+
 static int graph_link(struct asoc_simple_priv *priv,
 		      struct graph2_custom_hooks *hooks,
 		      enum graph_type gtype,
···
 			func = hooks->custom_dpcm;
 		else
 			func = audio_graph2_link_dpcm;
+		break;
+	case GRAPH_C2C:
+		if (hooks && hooks->custom_c2c)
+			func = hooks->custom_c2c;
+		else
+			func = audio_graph2_link_c2c;
 		break;
 	default:
 		break;
···
 	return 0;
 }
 
+static int graph_count_c2c(struct asoc_simple_priv *priv,
+			   struct device_node *lnk,
+			   struct link_info *li)
+{
+	struct device_node *ports = of_get_parent(lnk);
+	struct device_node *port0 = lnk;
+	struct device_node *port1 = of_get_next_child(ports, lnk);
+	struct device_node *ep0 = port_to_endpoint(port0);
+	struct device_node *ep1 = port_to_endpoint(port1);
+	struct device_node *codec0 = of_graph_get_remote_port(ep0);
+	struct device_node *codec1 = of_graph_get_remote_port(ep1);
+
+	of_node_get(lnk);
+
+	/*
+	 * codec2codec {
+	 *	ports {
+	 * =>	lnk:	port@0 { endpoint { ... }; };
+	 *		port@1 { endpoint { ... }; };
+	 *	};
+	 * };
+	 */
+	li->num[li->link].cpus		=
+	li->num[li->link].platforms	= graph_counter(codec0);
+	li->num[li->link].codecs	= graph_counter(codec1);
+	li->num[li->link].c2c		= 1;
+
+	of_node_put(ports);
+	of_node_put(port1);
+	of_node_put(ep0);
+	of_node_put(ep1);
+	of_node_put(codec0);
+	of_node_put(codec1);
+
+	return 0;
+}
+
 static int graph_count(struct asoc_simple_priv *priv,
 		       struct graph2_custom_hooks *hooks,
 		       enum graph_type gtype,
···
 		break;
 	case GRAPH_DPCM:
 		func = graph_count_dpcm;
+		break;
+	case GRAPH_C2C:
+		func = graph_count_c2c;
 		break;
 	default:
 		break;