diff --git a/soundtrigger/2.0/default/SoundTriggerHalImpl.cpp b/soundtrigger/2.0/default/SoundTriggerHalImpl.cpp
index 612772c..2de35e8 100644
--- a/soundtrigger/2.0/default/SoundTriggerHalImpl.cpp
+++ b/soundtrigger/2.0/default/SoundTriggerHalImpl.cpp
@@ -247,7 +247,7 @@
 }
 
 SoundTriggerHalImpl::SoundTriggerHalImpl()
-    : mModuleName("primary"), mHwDevice(NULL), mNextModelId(1) {}
+    : mModuleName("primary"), mNextModelId(1), mHwDevice(NULL) {}
 
 void SoundTriggerHalImpl::onFirstRef() {
     const hw_module_t* mod;
diff --git a/soundtrigger/2.0/default/SoundTriggerHalImpl.h b/soundtrigger/2.0/default/SoundTriggerHalImpl.h
index 5a9f0e1..fbe24c1 100644
--- a/soundtrigger/2.0/default/SoundTriggerHalImpl.h
+++ b/soundtrigger/2.0/default/SoundTriggerHalImpl.h
@@ -167,8 +167,11 @@
     static void recognitionCallback(struct sound_trigger_recognition_event* halEvent, void* cookie);
 
     const char* mModuleName;
-    struct sound_trigger_hw_device* mHwDevice;
+
     volatile atomic_uint_fast32_t mNextModelId;
+
+   protected:
+    struct sound_trigger_hw_device* mHwDevice;
     DefaultKeyedVector<int32_t, sp<SoundModelClient> > mClients;
     Mutex mLock;
 };
diff --git a/soundtrigger/2.2/Android.bp b/soundtrigger/2.2/Android.bp
new file mode 100644
index 0000000..0a7c2d8
--- /dev/null
+++ b/soundtrigger/2.2/Android.bp
@@ -0,0 +1,20 @@
+// This file is autogenerated by hidl-gen -Landroidbp.
+
+hidl_interface {
+    name: "android.hardware.soundtrigger@2.2",
+    root: "android.hardware",
+    vndk: {
+        enabled: true,
+    },
+    srcs: [
+        "ISoundTriggerHw.hal",
+    ],
+    interfaces: [
+        "android.hardware.audio.common@2.0",
+        "android.hardware.soundtrigger@2.0",
+        "android.hardware.soundtrigger@2.1",
+        "android.hidl.base@1.0",
+    ],
+    gen_java: false,
+}
+
diff --git a/soundtrigger/2.2/ISoundTriggerHw.hal b/soundtrigger/2.2/ISoundTriggerHw.hal
new file mode 100644
index 0000000..c503358
--- /dev/null
+++ b/soundtrigger/2.2/ISoundTriggerHw.hal
@@ -0,0 +1,40 @@
+/*
+ * Copyright 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.
+ */
+
+package android.hardware.soundtrigger@2.2;
+
+import @2.1::ISoundTriggerHw;
+import @2.0::SoundModelHandle;
+import @2.0::ISoundTriggerHwCallback.RecognitionEvent;
+
+/**
+ * SoundTrigger HAL interface. Used for hardware recognition of hotwords.
+ */
+interface ISoundTriggerHw extends @2.1::ISoundTriggerHw {
+
+    /**
+     * Get the state of a given model.
+     * The model state is returned as a RecognitionEvent.
+     * @param modelHandle The handle of the sound model to use for recognition
+     * @return retval Operation completion status: 0 in case of success,
+     *                -ENOSYS in case of invalid model handle,
+     *                -ENOMEM in case of memory allocation failure,
+     *                -ENODEV in case of initialization error.
+     * @return state  RecognitionEvent in case of success
+     */
+    getModelState(SoundModelHandle modelHandle)
+            generates (int32_t retval, RecognitionEvent state);
+};
diff --git a/soundtrigger/2.2/default/Android.mk b/soundtrigger/2.2/default/Android.mk
new file mode 100644
index 0000000..8c0f653
--- /dev/null
+++ b/soundtrigger/2.2/default/Android.mk
@@ -0,0 +1,50 @@
+#
+# 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.
+
+
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := android.hardware.soundtrigger@2.2-impl
+LOCAL_VENDOR_MODULE := true
+LOCAL_MODULE_RELATIVE_PATH := hw
+LOCAL_SRC_FILES := \
+    SoundTriggerHw.cpp
+
+LOCAL_CFLAGS := -Wall -Werror
+
+LOCAL_SHARED_LIBRARIES := \
+        libhardware \
+        libhidlbase \
+        libhidlmemory \
+        libhidltransport \
+        liblog \
+        libutils \
+        android.hardware.soundtrigger@2.2 \
+        android.hardware.soundtrigger@2.1 \
+        android.hardware.soundtrigger@2.0 \
+        android.hardware.soundtrigger@2.0-core \
+        android.hidl.allocator@1.0 \
+        android.hidl.memory@1.0
+
+LOCAL_C_INCLUDE_DIRS := $(LOCAL_PATH)
+
+ifeq ($(strip $(AUDIOSERVER_MULTILIB)),)
+LOCAL_MULTILIB := 32
+else
+LOCAL_MULTILIB := $(AUDIOSERVER_MULTILIB)
+endif
+
+include $(BUILD_SHARED_LIBRARY)
diff --git a/soundtrigger/2.2/default/SoundTriggerHw.cpp b/soundtrigger/2.2/default/SoundTriggerHw.cpp
new file mode 100644
index 0000000..90faf33
--- /dev/null
+++ b/soundtrigger/2.2/default/SoundTriggerHw.cpp
@@ -0,0 +1,110 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "SoundTriggerHw"
+
+#include "SoundTriggerHw.h"
+
+#include <android/log.h>
+#include <utility>
+
+namespace android {
+namespace hardware {
+namespace soundtrigger {
+namespace V2_2 {
+namespace implementation {
+
+Return<void> SoundTriggerHw::getModelState_2_2(int32_t modelHandle, getModelState_cb hidl_cb) {
+    sp<SoundModelClient> client;
+    if (mHwDevice == NULL) {
+        hidl_cb(-ENODEV, NULL);
+        return Void();
+    }
+
+    {
+        AutoMutex lock(mLock);
+        client = mClients.valueFor(modelHandle);
+        if (client == 0) {
+            hidl_cb(-ENOSYS, NULL);
+            return Void();
+        }
+    }
+
+    if (mHwDevice->get_model_state == NULL) {
+        ALOGE("Failed to get model state from device, no such method");
+        hidl_cb(-ENODEV, NULL);
+        return Void();
+    }
+
+    // Get the state from the device (as a recognition event)
+    struct sound_trigger_recognition_event* event =
+        mHwDevice->get_model_state(mHwDevice, client->getHalHandle());
+    if (event == NULL) {
+        ALOGE("Failed to get model state from device");
+        hidl_cb(-ENODEV, NULL);
+        return Void();
+    }
+
+    // Allocate shared memory to return to the client
+    sp<IAllocator> alloc = IAllocator::getService("ashmem");
+    if (alloc == 0) {
+        ALOGE("Failed to retrieve ashmem allocator service");
+        free(event);
+        hidl_cb(-ENOMEM, NULL);
+        return Void();
+    }
+    // Note: Only generic recognition events are currently supported
+    int n_bytes = sizeof(struct sound_trigger_generic_recognition_event);
+    bool success = false;
+    const hidl_memory& mem;
+    Return<void> r = ashmem->allocate(n_bytes, [&](bool s, const hidl_memory& m) {
+        success = s;
+        if (success) mem = m;
+    });
+    if (r.isOk() && success) {
+        // Copy the event data to the shared memory
+        sp<IMemory> memory = mapMemory(mem);
+        if (memory != 0) {
+            struct sound_trigger_generic_recognition_event* data =
+                (struct sound_trigger_generic_recognition_event*)memory->getPointer();
+            memory->update();
+            *data = *event;
+            memory->commit();
+
+            // Return the event memory via this callback
+            hidl_cb(0, memory);
+        } else {
+            ALOGE("Failed to map memory for recognition event");
+            hidl_cb(-ENOMEM, NULL);
+        }
+    } else {
+        ALOGE("Failed to allocate %d bytes from ashmem allocator service", n_bytes);
+        hidl_cb(-ENOMEM, NULL);
+    }
+
+    free(event);
+    return Void();
+}
+
+ISoundTriggerHw* HIDL_FETCH_ISoundTriggerHw(const char* /* name */) {
+    return (new SoundTriggerHw())->getInterface();
+}
+
+}  // namespace implementation
+}  // namespace V2_2
+}  // namespace soundtrigger
+}  // namespace hardware
+}  // namespace android
diff --git a/soundtrigger/2.2/default/SoundTriggerHw.h b/soundtrigger/2.2/default/SoundTriggerHw.h
new file mode 100644
index 0000000..7db54db
--- /dev/null
+++ b/soundtrigger/2.2/default/SoundTriggerHw.h
@@ -0,0 +1,114 @@
+/*
+ * 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_2_SOUNDTRIGGERHW_H
+#define ANDROID_HARDWARE_SOUNDTRIGGER_V2_2_SOUNDTRIGGERHW_H
+
+#include <SoundTriggerHalImpl.h>
+#include <android/hardware/soundtrigger/2.1/ISoundTriggerHw.h>
+#include <android/hardware/soundtrigger/2.2/ISoundTriggerHw.h>
+#include <hidl/Status.h>
+
+namespace android {
+namespace hardware {
+namespace soundtrigger {
+namespace V2_2 {
+namespace implementation {
+
+using ::android::sp;
+using ::android::hardware::Return;
+
+struct SoundTriggerHw : public V2_1::implementation::SoundTriggerHw {
+    SoundTriggerHw() = default;
+    ISoundTriggerHw* getInterface() { return new TrampolineSoundTriggerHw_2_2(this); }
+
+   protected:
+    virtual ~SoundTriggerHw() = default;
+
+    Return<sp<struct sound_trigger_recognition_event>> getModelState_2_2(
+        V2_0::SoundModelHandle modelHandle modelHandle);
+
+   private:
+    struct TrampolineSoundTriggerHw_2_2 : public ISoundTriggerHw {
+        explicit TrampolineSoundTriggerHw_2_2(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);
+        }
+
+        // Methods from V2_2::ISoundTriggerHw follow.
+        Return<void> getModelState(int32_t modelHandle, getModelState_cb hidl_cb) override {
+            return mImpl->getModelState_2_2(modelHandle, hidl_cb);
+        }
+
+       private:
+        sp<SoundTriggerHw> mImpl;
+    };
+};
+
+extern "C" ISoundTriggerHw* HIDL_FETCH_ISoundTriggerHw(const char* name);
+
+}  // namespace implementation
+}  // namespace V2_2
+}  // namespace soundtrigger
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_SOUNDTRIGGER_V2_2_SOUNDTRIGGERHW_H
diff --git a/soundtrigger/2.2/vts/functional/Android.bp b/soundtrigger/2.2/vts/functional/Android.bp
new file mode 100644
index 0000000..adbd018
--- /dev/null
+++ b/soundtrigger/2.2/vts/functional/Android.bp
@@ -0,0 +1,29 @@
+//
+// 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.
+//
+
+cc_test {
+    name: "VtsHalSoundtriggerV2_2TargetTest",
+    defaults: ["VtsHalTargetTestDefaults"],
+    srcs: ["VtsHalSoundtriggerV2_2TargetTest.cpp"],
+    static_libs: [
+                 "android.hidl.allocator@1.0",
+                 "android.hidl.memory@1.0",
+                 "android.hardware.soundtrigger@2.0",
+                 "android.hardware.soundtrigger@2.1",
+                 "android.hardware.soundtrigger@2.2",
+                 "libhidlmemory"
+                 ],
+}
diff --git a/soundtrigger/2.2/vts/functional/VtsHalSoundtriggerV2_2TargetTest.cpp b/soundtrigger/2.2/vts/functional/VtsHalSoundtriggerV2_2TargetTest.cpp
new file mode 100644
index 0000000..ed5149f
--- /dev/null
+++ b/soundtrigger/2.2/vts/functional/VtsHalSoundtriggerV2_2TargetTest.cpp
@@ -0,0 +1,101 @@
+/*
+ * 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.
+ */
+
+#define LOG_TAG "SoundTriggerHidlHalTest"
+#include <stdlib.h>
+#include <time.h>
+
+#include <condition_variable>
+#include <mutex>
+
+#include <android/log.h>
+#include <cutils/native_handle.h>
+#include <log/log.h>
+
+#include <android/hardware/audio/common/2.0/types.h>
+#include <android/hardware/soundtrigger/2.0/ISoundTriggerHw.h>
+#include <android/hardware/soundtrigger/2.2/ISoundTriggerHw.h>
+
+#include <VtsHalHidlTargetTestBase.h>
+#include <VtsHalHidlTargetTestEnvBase.h>
+
+using ::android::sp;
+using ::android::hardware::Return;
+using ::android::hardware::soundtrigger::V2_0::ISoundTriggerHwCallback;
+using ::android::hardware::soundtrigger::V2_0::SoundModelHandle;
+using ::android::hardware::soundtrigger::V2_2::ISoundTriggerHw;
+
+// Test environment for SoundTrigger HIDL HAL.
+class SoundTriggerHidlEnvironment : public ::testing::VtsHalHidlTargetTestEnvBase {
+   public:
+    // get the test environment singleton
+    static SoundTriggerHidlEnvironment* Instance() {
+        static SoundTriggerHidlEnvironment* instance = new SoundTriggerHidlEnvironment;
+        return instance;
+    }
+
+    void registerTestServices() override { registerTestService<ISoundTriggerHw>(); }
+
+   private:
+    SoundTriggerHidlEnvironment() {}
+};
+
+// The main test class for Sound Trigger HIDL HAL.
+class SoundTriggerHidlTest : public ::testing::VtsHalHidlTargetTestBase {
+   public:
+    void SetUp() override {
+        mSoundTriggerHal = ::testing::VtsHalHidlTargetTestBase::getService<ISoundTriggerHw>(
+            SoundTriggerHidlEnvironment::Instance()->getServiceName<ISoundTriggerHw>());
+        ASSERT_NE(nullptr, mSoundTriggerHal.get());
+    }
+
+    static void SetUpTestCase() { srand(1234); }
+
+    void TearDown() override {}
+
+   protected:
+    sp<ISoundTriggerHw> mSoundTriggerHal;
+};
+
+/**
+ * Test ISoundTriggerHw::getModelState() method
+ *
+ * Verifies that:
+ *  - the implementation returns -EINVAL with invalid model handle
+ *
+ */
+TEST_F(SoundTriggerHidlTest, GetModelStateInvalidModel) {
+    int ret = android::OK;
+    ISoundTriggerHwCallback::RecognitionEvent event;
+    SoundModelHandle handle = 0;
+    Return<void> hidlReturn =
+        mSoundTriggerHal->getModelState(handle, [&](int32_t retval, auto res) {
+            ret = retval;
+            event = res;
+        });
+
+    EXPECT_TRUE(hidlReturn.isOk());
+    EXPECT_EQ(-ENOSYS, ret);
+}
+
+int main(int argc, char** argv) {
+    ::testing::AddGlobalTestEnvironment(SoundTriggerHidlEnvironment::Instance());
+    ::testing::InitGoogleTest(&argc, argv);
+    SoundTriggerHidlEnvironment::Instance()->init(&argc, argv);
+    int status = RUN_ALL_TESTS();
+    ALOGI("Test result = %d", status);
+    return status;
+}