diff --git a/include/hardware/audio_hal.h b/include/hardware/audio_hal.h
new file mode 100644
index 0000000..50675bd
--- /dev/null
+++ b/include/hardware/audio_hal.h
@@ -0,0 +1,298 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+#ifndef ANDROID_AUDIO_HAL_INTERFACE_H
+#define ANDROID_AUDIO_HAL_INTERFACE_H
+
+#include <stdint.h>
+#include <strings.h>
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <cutils/bitops.h>
+
+#include <hardware/hardware.h>
+#include <hardware/audio.h>
+
+__BEGIN_DECLS
+
+/**
+ * The id of this module
+ */
+#define AUDIO_HARDWARE_MODULE_ID "audio"
+
+/**
+ * Name of the audio devices to open
+ */
+#define AUDIO_HARDWARE_INTERFACE "audio_hw_if"
+
+/**************************************/
+
+/* common audio stream parameters and operations */
+struct audio_stream {
+
+    /**
+     * sampling rate is in Hz - eg. 44100
+     */
+    uint32_t (*get_sample_rate)(const struct audio_stream *stream);
+    int (*set_sample_rate)(struct audio_stream *stream, uint32_t rate);
+
+    /**
+     * size of output buffer in bytes - eg. 4800
+     */
+    size_t (*get_buffer_size)(const struct audio_stream *stream);
+
+    /**
+     * the channel mask -
+     *  e.g. AUDIO_CHANNEL_OUT_STEREO or AUDIO_CHANNEL_IN_STEREO
+     */
+    uint32_t (*get_channels)(const struct audio_stream *stream);
+
+    /**
+     * audio format - eg. AUDIO_FORMAT_PCM_16_BIT
+     */
+    int (*get_format)(const struct audio_stream *stream);
+    int (*set_format)(struct audio_stream *stream, int format);
+
+    /**
+     * Put the audio hardware input/output into standby mode.
+     * Returns 0 on success and <0 on failure.
+     */
+    int (*standby)(struct audio_stream *stream);
+
+    /** dump the state of the audio input/output device */
+    int (*dump)(const struct audio_stream *stream, int fd);
+
+    audio_devices_t (*get_device)(const struct audio_stream *stream);
+    int (*set_device)(struct audio_stream *stream, audio_devices_t device);
+
+    /**
+     * set/get audio stream parameters. The function accepts a list of
+     * parameter key value pairs in the form: key1=value1;key2=value2;...
+     *
+     * Some keys are reserved for standard parameters (See AudioParameter class)
+     *
+     * If the implementation does not accept a parameter change while
+     * the output is active but the parameter is acceptable otherwise, it must
+     * return -ENOSYS.
+     *
+     * The audio flinger will put the stream in standby and then change the
+     * parameter value.
+     */
+    int (*set_parameters)(struct audio_stream *stream, const char *kv_pairs);
+
+    /*
+     * Returns a pointer to a heap allocated string. The caller is responsible
+     * for freeing the memory for it.
+     */
+    char * (*get_parameters)(const struct audio_stream *stream,
+                             const char *keys);
+};
+typedef struct audio_stream audio_stream_t;
+
+/**
+ * audio_stream_out is the abstraction interface for the audio output hardware.
+ *
+ * It provides information about various properties of the audio output
+ * hardware driver.
+ */
+
+struct audio_stream_out {
+    struct audio_stream common;
+
+    /**
+     * return the audio hardware driver latency in milli seconds.
+     */
+    uint32_t (*get_latency)(const struct audio_stream_out *stream);
+
+    /**
+     * Use this method in situations where audio mixing is done in the
+     * hardware. This method serves as a direct interface with hardware,
+     * allowing you to directly set the volume as apposed to via the framework.
+     * This method might produce multiple PCM outputs or hardware accelerated
+     * codecs, such as MP3 or AAC.
+     */
+    int (*set_volume)(struct audio_stream_out *stream, float left, float right);
+
+    /**
+     * write audio buffer to driver. Returns number of bytes written
+     */
+    ssize_t (*write)(struct audio_stream_out *stream, const void* buffer,
+                     size_t bytes);
+
+    /* return the number of audio frames written by the audio dsp to DAC since
+     * the output has exited standby
+     */
+    int (*get_render_position)(const struct audio_stream_out *stream,
+                               uint32_t *dsp_frames);
+};
+typedef struct audio_stream_out audio_stream_out_t;
+
+struct audio_stream_in {
+    struct audio_stream common;
+
+    /** set the input gain for the audio driver. This method is for
+     *  for future use */
+    int (*set_gain)(struct audio_stream_in *stream, float gain);
+
+    /** read audio buffer in from audio driver */
+    ssize_t (*read)(struct audio_stream_in *stream, void* buffer,
+                    size_t bytes);
+
+    /**
+     * Return the amount of input frames lost in the audio driver since the
+     * last call of this function.
+     * Audio driver is expected to reset the value to 0 and restart counting
+     * upon returning the current value by this function call.
+     * Such loss typically occurs when the user space process is blocked
+     * longer than the capacity of audio driver buffers.
+     *
+     * Unit: the number of input audio frames
+     */
+    uint32_t (*get_input_frames_lost)(struct audio_stream_in *stream);
+};
+typedef struct audio_stream_in audio_stream_in_t;
+
+/**
+ * return the frame size (number of bytes per sample).
+ */
+static inline uint32_t audio_stream_frame_size(struct audio_stream *s)
+{
+    int chan_samp_sz;
+
+    switch (s->get_format(s)) {
+    case AUDIO_FORMAT_PCM_16_BIT:
+        chan_samp_sz = sizeof(int16_t);
+        break;
+    case AUDIO_FORMAT_PCM_8_BIT:
+    default:
+        chan_samp_sz = sizeof(int8_t);
+        break;
+    }
+
+    return popcount(s->get_channels(s)) * chan_samp_sz;
+}
+
+
+/**********************************************************************/
+
+/**
+ * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
+ * and the fields of this data structure must begin with hw_module_t
+ * followed by module specific information.
+ */
+struct audio_module {
+    struct hw_module_t common;
+};
+
+struct audio_hw_device {
+    struct hw_device_t common;
+
+    /**
+     * used by audio flinger to enumerate what devices are supported by
+     * each audio_hw_device implementation.
+     *
+     * Return value is a bitmask of 1 or more values of audio_devices_t
+     */
+    uint32_t (*get_supported_devices)(const struct audio_hw_device *dev);
+
+    /**
+     * check to see if the audio hardware interface has been initialized.
+     * returns 0 on success, -ENODEV on failure.
+     */
+    int (*init_check)(const struct audio_hw_device *dev);
+
+    /** set the audio volume of a voice call. Range is between 0.0 and 1.0 */
+    int (*set_voice_volume)(struct audio_hw_device *dev, float volume);
+
+    /**
+     * set the audio volume for all audio activities other than voice call.
+     * Range between 0.0 and 1.0. If any value other than 0 is returned,
+     * the software mixer will emulate this capability.
+     */
+    int (*set_master_volume)(struct audio_hw_device *dev, float volume);
+
+    /**
+     * setMode is called when the audio mode changes. AUDIO_MODE_NORMAL mode
+     * is for standard audio playback, AUDIO_MODE_RINGTONE when a ringtone is
+     * playing, and AUDIO_MODE_IN_CALL when a call is in progress.
+     */
+    int (*set_mode)(struct audio_hw_device *dev, int mode);
+
+    /* mic mute */
+    int (*set_mic_mute)(struct audio_hw_device *dev, bool state);
+    int (*get_mic_mute)(const struct audio_hw_device *dev, bool *state);
+
+    /* set/get global audio parameters */
+    int (*set_parameters)(struct audio_hw_device *dev, const char *kv_pairs);
+
+    /*
+     * Returns a pointer to a heap allocated string. The caller is responsible
+     * for freeing the memory for it.
+     */
+    char * (*get_parameters)(const struct audio_hw_device *dev,
+                             const char *keys);
+
+    /* Returns audio input buffer size according to parameters passed or
+     * 0 if one of the parameters is not supported
+     */
+    size_t (*get_input_buffer_size)(const struct audio_hw_device *dev,
+                                    uint32_t sample_rate, int format,
+                                    int channel_count);
+
+    /** This method creates and opens the audio hardware output stream */
+    int (*open_output_stream)(struct audio_hw_device *dev, uint32_t devices,
+                              int *format, uint32_t *channels,
+                              uint32_t *sample_rate,
+                              struct audio_stream_out **out);
+
+    void (*close_output_stream)(struct audio_hw_device *dev,
+                                struct audio_stream_out* out);
+
+    /** This method creates and opens the audio hardware input stream */
+    int (*open_input_stream)(struct audio_hw_device *dev, uint32_t devices,
+                             int *format, uint32_t *channels,
+                             uint32_t *sample_rate,
+                             audio_in_acoustics_t acoustics,
+                             struct audio_stream_in **stream_in);
+
+    void (*close_input_stream)(struct audio_hw_device *dev,
+                               struct audio_stream_in *in);
+
+    /** This method dumps the state of the audio hardware */
+    int (*dump)(const struct audio_hw_device *dev, int fd);
+};
+typedef struct audio_hw_device audio_hw_device_t;
+
+/** convenience API for opening and closing a supported device */
+
+static inline int audio_hw_device_open(const struct hw_module_t* module,
+                                       struct audio_hw_device** device)
+{
+    return module->methods->open(module, AUDIO_HARDWARE_INTERFACE,
+                                 (struct hw_device_t**)device);
+}
+
+static inline int audio_hw_device_close(struct audio_hw_device* device)
+{
+    return device->common.close(&device->common);
+}
+
+
+__END_DECLS
+
+#endif  // ANDROID_AUDIO_INTERFACE_H