Define HAL for audio effects

Created after hardware/audio_effect.h with the following changes:

 - names changed to satisfy HAL style guide;

 - defined an interface per effect, an interface method
   per command, and getter / setter methods for properties;

 - retained methods for executing proprietary commands
   and accessing proprietary properties, only to be used
   for third-party software effects;

 - HIDL vector type is used instead of count / array pairs;

 - provider callback changed to be used over RPC;

 - 'dump' is method is already defined by generated code.

Note that audio data is currently transferred using AudioBuffers,
which is not effective due to memory copy and HwBinder transaction
involved. The transfer method will be changed to FastMessageQueue.

Bug: 30222631
Test: make
Change-Id: Ic8ea5c19688610ebe642c7597d2bcfa3226977e7
diff --git a/audio/effect/2.0/IEffectsFactory.hal b/audio/effect/2.0/IEffectsFactory.hal
new file mode 100644
index 0000000..6763825
--- /dev/null
+++ b/audio/effect/2.0/IEffectsFactory.hal
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+package android.hardware.audio.effect@2.0;
+
+import android.hardware.audio.common@2.0;
+import IEffect;
+
+interface IEffectsFactory {
+    /*
+     * Returns descriptors of different effects in all loaded libraries.
+     *
+     * @return retval operation completion status.
+     * @return result list of effect descriptors.
+     */
+    getAllDescriptors() generates(Result retval, vec<EffectDescriptor> result);
+
+    /*
+     * Returns a descriptor of a particular effect.
+     *
+     * @return retval operation completion status.
+     * @return result effect descriptor.
+     */
+    getDescriptor(Uuid uid) generates(Result retval, EffectDescriptor result);
+
+    /*
+     * Creates an effect engine of the specified type.  To release the effect
+     * engine, it is necessary to release references to the returned effect
+     * object.
+     *
+     * @param uid effect uuid.
+     * @param session audio session to which this effect instance will be
+     *                attached.  All effects created with the same session ID
+     *                are connected in series and process the same signal
+     *                stream.
+     * @param ioHandle identifies the output or input stream this effect is
+     *                 directed to in audio HAL.
+     * @return retval operation completion status.
+     * @return result the interface for the created effect.
+     */
+    createEffect(Uuid uid, AudioSession session, AudioIoHandle ioHandle)
+            generates (Result retval, IEffect result);
+
+    /*
+     * Dumps information about effects into the provided file descriptor.
+     * This is used for the dumpsys facility.
+     *
+     * @param fd dump file descriptor.
+     */
+    debugDump(handle fd);
+};