topology: Parse physical DAIs in text conf file

Add support for parsing physical DAIs in the text configuration file.
The syntax of physical DAIs is described in document in topology.h

Signed-off-by: Mengdong Lin <mengdong.lin@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/topology.h

@@ -663,6 +663,36 @@ extern "C" {
  * }
  * </pre>
  *
+ * <h4>Physical DAI</h4>
+ * A physical DAI (e.g. backend DAI for DPCM) is defined as a new section
+ * that can include a unique ID, playback and capture stream capabilities,
+ * optional flags, and private data. <br>
+ * Its PCM stream capablities are same as those for PCM objects,
+ * please refer to section 'PCM Capabilities'.
+ *
+ * <pre>
+ * SectionDAI."name" {
+ *
+ *	index "1"			# Index number
+ *
+ *	id "0"				# used for binding to the Backend DAI
+ *
+ *	pcm."playback" {
+ *		capabilities "capabilities1"	# capabilities for playback
+ *	}
+ *
+ *	pcm."capture" {
+ *		capabilities "capabilities2"	# capabilities for capture
+ *	}
+ *
+ *	symmetric_rates "true"			# optional flags
+ *	symmetric_channels "true"
+ *	symmetric_sample_bits "false"
+ *
+ *	data "name"			# optional private data
+ * }
+ * </pre>
+ *
  * <h4>Manifest Private Data</h4>
  * Manfiest may have private data. Users need to define a manifest section
  * and add the references to 1 or multiple data sections. Please refer to
@@ -735,6 +765,7 @@ enum snd_tplg_type {
 	SND_TPLG_TYPE_TUPLE,		/*!< Vendor tuples */
 	SND_TPLG_TYPE_LINK,		/*!< Physical DAI link */
 	SND_TPLG_TYPE_HW_CONFIG,	/*!< Link HW config */
+	SND_TPLG_TYPE_DAI,		/*!< Physical DAI */
 };
 
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