doc: reference: Add pages for audio

Add reference pages for the following APIs:

- Audio Codec
- DMIC

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

doc/reference/audio/codec.rst

@@ -0,0 +1,22 @@
+.. _audio_codec_api:
+
+Audio Codec
+###########
+
+Overview
+********
+
+The Audio Codec API provides access to digital audio codecs.
+
+Configuration Options
+*********************
+
+Related configuration options:
+
+* :option:`CONFIG_AUDIO_CODEC`
+
+API Reference
+*************
+
+.. doxygengroup:: audio_codec_interface
+   :project: Zephyr

doc/reference/audio/dmic.rst

@@ -0,0 +1,22 @@
+.. _audio_dmic_api:
+
+DMIC
+####
+
+Overview
+********
+
+The audio DMIC interface provides access to digital microphones.
+
+Configuration Options
+*********************
+
+Related configuration options:
+
+* :option:`CONFIG_AUDIO_DMIC`
+
+API Reference
+*************
+
+.. doxygengroup:: audio_dmic_interface
+   :project: Zephyr

doc/reference/audio/index.rst

@@ -0,0 +1,10 @@
+.. _audio_reference:
+
+Audio
+#####
+
+.. toctree::
+   :maxdepth: 1
+
+   codec.rst
+   dmic.rst

doc/reference/index.rst

@@ -7,6 +7,7 @@ API Reference
    :maxdepth: 1
 
    terminology.rst
+   audio/index.rst
    bluetooth/index.rst
    kconfig/index.rst
    crypto/index.rst

include/audio/codec.h

@@ -14,6 +14,13 @@
 #ifndef ZEPHYR_INCLUDE_AUDIO_CODEC_H_
 #define ZEPHYR_INCLUDE_AUDIO_CODEC_H_
 
+/**
+ * @brief Abstraction for audio codecs
+ *
+ * @defgroup audio_codec_interface Audio Codec Interface
+ * @{
+ */
+
 #include <drivers/i2s.h>
 
 #ifdef __cplusplus
@@ -217,4 +224,8 @@ static inline int audio_codec_apply_properties(struct device *dev)
 }
 #endif
 
+/**
+ * @}
+ */
+
 #endif /* ZEPHYR_INCLUDE_AUDIO_CODEC_H_ */

include/audio/dmic.h

@@ -7,9 +7,23 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+/**
+ * @file
+ * @brief Public API header file for Digital Microphones
+ *
+ * This file contains the Digital Microphone APIs
+ */
+
 #ifndef ZEPHYR_INCLUDE_AUDIO_DMIC_H_
 #define ZEPHYR_INCLUDE_AUDIO_DMIC_H_
 
+/**
+ * @brief Abstraction for digital microphones
+ *
+ * @defgroup audio_dmic_interface Digital Microphone Interface
+ * @{
+ */
+
 #include <kernel.h>
 #include <device.h>
 
@@ -276,4 +290,8 @@ static inline int dmic_read(struct device *dev, u8_t stream, void **buffer,
 }
 #endif
 
+/**
+ * @}
+ */
+
 #endif /* ZEPHYR_INCLUDE_AUDIO_DMIC_H_ */