diff --git a/soundtrigger/2.1/default/SoundTriggerHw.h b/soundtrigger/2.1/default/SoundTriggerHw.h
new file mode 100644
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+++ b/soundtrigger/2.1/default/SoundTriggerHw.h
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2018 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_HARDWARE_SOUNDTRIGGER_V2_1_SOUNDTRIGGERHW_H
+#define ANDROID_HARDWARE_SOUNDTRIGGER_V2_1_SOUNDTRIGGERHW_H
+
+#include <SoundTriggerHalImpl.h>
+#include <android/hardware/soundtrigger/2.1/ISoundTriggerHw.h>
+#include <hidl/Status.h>
+
+namespace android {
+namespace hardware {
+namespace soundtrigger {
+namespace V2_1 {
+namespace implementation {
+
+using ::android::sp;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+
+struct SoundTriggerHw : public V2_0::implementation::SoundTriggerHalImpl {
+    SoundTriggerHw() = default;
+    ISoundTriggerHw* getInterface() { return new TrampolineSoundTriggerHw_2_1(this); }
+
+   protected:
+    virtual ~SoundTriggerHw() = default;
+
+    Return<void> loadSoundModel_2_1(const V2_1::ISoundTriggerHw::SoundModel& soundModel,
+                                    const sp<V2_1::ISoundTriggerHwCallback>& callback,
+                                    int32_t cookie,
+                                    V2_1::ISoundTriggerHw::loadSoundModel_2_1_cb _hidl_cb);
+    Return<void> loadPhraseSoundModel_2_1(
+        const V2_1::ISoundTriggerHw::PhraseSoundModel& soundModel,
+        const sp<V2_1::ISoundTriggerHwCallback>& callback, int32_t cookie,
+        V2_1::ISoundTriggerHw::loadPhraseSoundModel_2_1_cb _hidl_cb);
+    Return<int32_t> startRecognition_2_1(int32_t modelHandle,
+                                         const V2_1::ISoundTriggerHw::RecognitionConfig& config);
+
+   private:
+    struct TrampolineSoundTriggerHw_2_1 : public ISoundTriggerHw {
+        explicit TrampolineSoundTriggerHw_2_1(sp<SoundTriggerHw> impl) : mImpl(impl) {}
+
+        // Methods from ::android::hardware::soundtrigger::V2_0::ISoundTriggerHw follow.
+        Return<void> getProperties(getProperties_cb _hidl_cb) override {
+            return mImpl->getProperties(_hidl_cb);
+        }
+        Return<void> loadSoundModel(const V2_0::ISoundTriggerHw::SoundModel& soundModel,
+                                    const sp<V2_0::ISoundTriggerHwCallback>& callback,
+                                    int32_t cookie, loadSoundModel_cb _hidl_cb) override {
+            return mImpl->loadSoundModel(soundModel, callback, cookie, _hidl_cb);
+        }
+        Return<void> loadPhraseSoundModel(const V2_0::ISoundTriggerHw::PhraseSoundModel& soundModel,
+                                          const sp<V2_0::ISoundTriggerHwCallback>& callback,
+                                          int32_t cookie,
+                                          loadPhraseSoundModel_cb _hidl_cb) override {
+            return mImpl->loadPhraseSoundModel(soundModel, callback, cookie, _hidl_cb);
+        }
+        Return<int32_t> unloadSoundModel(V2_0::SoundModelHandle modelHandle) override {
+            return mImpl->unloadSoundModel(modelHandle);
+        }
+        Return<int32_t> startRecognition(int32_t modelHandle,
+                                         const V2_0::ISoundTriggerHw::RecognitionConfig& config,
+                                         const sp<V2_0::ISoundTriggerHwCallback>& /*callback*/,
+                                         int32_t /*cookie*/) override {
+            return mImpl->startRecognition(modelHandle, config);
+        }
+        Return<int32_t> stopRecognition(V2_0::SoundModelHandle modelHandle) override {
+            return mImpl->stopRecognition(modelHandle);
+        }
+        Return<int32_t> stopAllRecognitions() override { return mImpl->stopAllRecognitions(); }
+
+        // Methods from V2_1::ISoundTriggerHw follow.
+        Return<void> loadSoundModel_2_1(const V2_1::ISoundTriggerHw::SoundModel& soundModel,
+                                        const sp<V2_1::ISoundTriggerHwCallback>& callback,
+                                        int32_t cookie, loadSoundModel_2_1_cb _hidl_cb) override {
+            return mImpl->loadSoundModel_2_1(soundModel, callback, cookie, _hidl_cb);
+        }
+        Return<void> loadPhraseSoundModel_2_1(
+            const V2_1::ISoundTriggerHw::PhraseSoundModel& soundModel,
+            const sp<V2_1::ISoundTriggerHwCallback>& callback, int32_t cookie,
+            loadPhraseSoundModel_2_1_cb _hidl_cb) override {
+            return mImpl->loadPhraseSoundModel_2_1(soundModel, callback, cookie, _hidl_cb);
+        }
+        Return<int32_t> startRecognition_2_1(int32_t modelHandle,
+                                             const V2_1::ISoundTriggerHw::RecognitionConfig& config,
+                                             const sp<V2_1::ISoundTriggerHwCallback>& /*callback*/,
+                                             int32_t /*cookie*/) override {
+            return mImpl->startRecognition_2_1(modelHandle, config);
+        }
+        Return<void> getParameters(const hidl_vec<hidl_string>& /*keys*/,
+                                   getParameters_cb _hidl_cb) override {
+            _hidl_cb(-ENOSYS, hidl_vec<ParameterValue>());
+            return Void();
+        }
+        Return<int32_t> setParameters(
+            const hidl_vec<V2_1::ISoundTriggerHw::ParameterValue>& /*parameters*/) override {
+            return -ENOSYS;
+        }
+        Return<void> getSoundModelParameters(int32_t /*modelHandle*/,
+                                             const hidl_vec<hidl_string>& /*keys*/,
+                                             getSoundModelParameters_cb _hidl_cb) override {
+            _hidl_cb(-ENOSYS, hidl_vec<ParameterValue>());
+            return Void();
+        }
+        Return<int32_t> setSoundModelParameters(
+            int32_t /*modelHandle*/,
+            const hidl_vec<V2_1::ISoundTriggerHw::ParameterValue>& /*parameters*/) override {
+            return -ENOSYS;
+        }
+
+       private:
+        sp<SoundTriggerHw> mImpl;
+    };
+
+    class SoundModelClient_2_1 : public SoundModelClient {
+       public:
+        SoundModelClient_2_1(uint32_t id, V2_1::ISoundTriggerHwCallback::CallbackCookie cookie,
+                             sp<V2_1::ISoundTriggerHwCallback> callback)
+            : SoundModelClient(id, cookie), mCallback(callback) {}
+
+        void recognitionCallback(struct sound_trigger_recognition_event* halEvent) override;
+        void soundModelCallback(struct sound_trigger_model_event* halEvent) override;
+
+       private:
+        sp<V2_1::ISoundTriggerHwCallback> mCallback;
+    };
+};
+
+extern "C" ISoundTriggerHw* HIDL_FETCH_ISoundTriggerHw(const char* name);
+
+}  // namespace implementation
+}  // namespace V2_1
+}  // namespace soundtrigger
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_SOUNDTRIGGER_V2_1_SOUNDTRIGGERHW_H