Add custom audio amplifier for TFA amp feedback

* Based on observing reverse engineering from davinci stock audio HAL.
 * Fixes speaker distortion on high volume.

 * Same logic with Smosia, rewritten by me.

Co-authored-by: Smosia <stasenko_nv@nrcki.ru>
Change-Id: I369555a9fcb06065177636b436d2e006c7a0b07d

audio_amplifier/Android.mk

@@ -0,0 +1,58 @@
+#
+# Copyright 2020 The LineageOS 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.
+#
+
+LOCAL_PATH := $(call my-dir)
+
+ifeq ($(strip $(AUDIO_FEATURE_ENABLED_EXT_AMPLIFIER)),true)
+
+include $(CLEAR_VARS)
+LOCAL_SHARED_LIBRARIES := \
+    libbase \
+    liblog \
+    libcutils \
+    libtinyalsa \
+    libtinycompress \
+    libaudioroute \
+    libdl \
+    libaudioutils \
+    libhwbinder \
+    libhidlbase \
+    libprocessgroup \
+    libutils \
+    audio.primary.$(TARGET_BOARD_PLATFORM)
+
+LOCAL_C_INCLUDES += \
+    external/tinyalsa/include \
+    external/tinycompress/include \
+    hardware/libhardware/include \
+    system/media/audio_utils/include \
+    $(call include-path-for, audio-effects) \
+    $(call include-path-for, audio-route) \
+    $(call project-path-for,qcom-audio)/hal \
+    $(call project-path-for,qcom-audio)/hal/msm8974 \
+    $(call project-path-for,qcom-audio)/hal/audio_extn \
+    $(call project-path-for,qcom-audio)/hal/voice_extn
+
+LOCAL_HEADER_LIBRARIES := generated_kernel_headers
+LOCAL_SRC_FILES := audio_amplifier.c
+LOCAL_MODULE := audio_amplifier.$(TARGET_BOARD_PLATFORM)
+LOCAL_MODULE_RELATIVE_PATH := hw
+LOCAL_MODULE_TAGS := optional
+LOCAL_VENDOR_MODULE := true
+
+include $(BUILD_SHARED_LIBRARY)
+
+endif