diff --git a/soundtrigger/2.1/Android.bp b/soundtrigger/2.1/Android.bp
new file mode 100644
index 0000000..ed1ec3d
--- /dev/null
+++ b/soundtrigger/2.1/Android.bp
@@ -0,0 +1,20 @@
+// This file is autogenerated by hidl-gen -Landroidbp.
+
+hidl_interface {
+    name: "android.hardware.soundtrigger@2.1",
+    root: "android.hardware",
+    vndk: {
+        enabled: true,
+    },
+    srcs: [
+        "ISoundTriggerHw.hal",
+        "ISoundTriggerHwCallback.hal",
+    ],
+    interfaces: [
+        "android.hardware.audio.common@2.0",
+        "android.hardware.soundtrigger@2.0",
+        "android.hidl.base@1.0",
+    ],
+    gen_java: false,
+}
+
diff --git a/soundtrigger/2.1/ISoundTriggerHw.hal b/soundtrigger/2.1/ISoundTriggerHw.hal
new file mode 100644
index 0000000..2f2e73a
--- /dev/null
+++ b/soundtrigger/2.1/ISoundTriggerHw.hal
@@ -0,0 +1,234 @@
+/*
+ * Copyright 2017 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@2.1;
+
+import @2.0::ISoundTriggerHw;
+import @2.0::ISoundTriggerHwCallback.CallbackCookie;
+import @2.0::SoundModelHandle;
+
+import ISoundTriggerHwCallback;
+
+/**
+ * SoundTrigger HAL interface. Used for hardware recognition of hotwords.
+ */
+interface ISoundTriggerHw extends @2.0::ISoundTriggerHw {
+
+    /**
+     * Base sound model descriptor. This struct is the header of a larger block
+     * passed to loadSoundModel_2_1() and contains the binary data of the
+     * sound model.
+     */
+    struct SoundModel {
+        /** Sound model header. Any data contained in the 'header.data' field
+         * is ignored */
+        @2.0::ISoundTriggerHw.SoundModel header;
+        /** Opaque data transparent to Android framework */
+        memory data;
+    };
+
+    /**
+     * Specialized sound model for key phrase detection.
+     * Proprietary representation of key phrases in binary data must match
+     * information indicated by phrases field.
+     */
+    struct PhraseSoundModel {
+        /** Common part of sound model descriptor */
+        SoundModel  common;
+        /** List of descriptors for key phrases supported by this sound model */
+        vec<Phrase> phrases;
+    };
+
+    /**
+     * Configuration for sound trigger capture session passed to
+     * startRecognition_2_1() method.
+     */
+    struct RecognitionConfig {
+        /** Configuration header. Any data contained in the 'header.data' field
+         * is ignored */
+        @2.0::ISoundTriggerHw.RecognitionConfig header;
+        /** Opaque capture configuration data transparent to the framework */
+        memory data;
+    };
+
+    /**
+     * Load a sound model. Once loaded, recognition of this model can be
+     * started and stopped. Only one active recognition per model at a time.
+     * The SoundTrigger service must handle concurrent recognition requests by
+     * different users/applications on the same model.
+     * The implementation returns a unique handle used by other functions
+     * (unloadSoundModel(), startRecognition*(), etc...
+     *
+     * Must have the exact same semantics as loadSoundModel from
+     * ISoundTriggerHw@2.0 except that the SoundModel uses shared memory
+     * instead of data.
+     *
+     * @param soundModel A SoundModel structure describing the sound model
+     *     to load.
+     * @param callback The callback interface on which the soundmodelCallback*()
+     *     method must be called upon completion.
+     * @param cookie The value of the cookie argument passed to the completion
+     *     callback. This unique context information is assigned and
+     *     used only by the framework.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid sound model (e.g 0 data size),
+     *     -ENOSYS in case of invalid operation (e.g max number of models
+     *             exceeded),
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     * @return modelHandle A unique handle assigned by the HAL for use by the
+     *     framework when controlling activity for this sound model.
+     */
+    @callflow(next={"startRecognition_2_1", "setSoundModelParameters", "unloadSoundModel"})
+    loadSoundModel_2_1(SoundModel soundModel,
+                   ISoundTriggerHwCallback callback,
+                   CallbackCookie cookie)
+            generates (int32_t retval, SoundModelHandle modelHandle);
+
+    /**
+     * Load a key phrase sound model. Once loaded, recognition of this model can
+     * be started and stopped. Only one active recognition per model at a time.
+     * The SoundTrigger service must handle concurrent recognition requests by
+     * different users/applications on the same model.
+     * The implementation returns a unique handle used by other functions
+     * (unloadSoundModel(), startRecognition*(), etc...
+     *
+     * Must have the exact same semantics as loadPhraseSoundModel from
+     * ISoundTriggerHw@2.0 except that the PhraseSoundModel uses shared memory
+     * instead of data.
+     *
+     * @param soundModel A PhraseSoundModel structure describing the sound model
+     *     to load.
+     * @param callback The callback interface on which the soundmodelCallback*()
+     *     method must be called upon completion.
+     * @param cookie The value of the cookie argument passed to the completion
+     *     callback. This unique context information is assigned and
+     *     used only by the framework.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid sound model (e.g 0 data size),
+     *     -ENOSYS in case of invalid operation (e.g max number of models
+     *             exceeded),
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     * @return modelHandle A unique handle assigned by the HAL for use by the
+     *     framework when controlling activity for this sound model.
+     */
+    @callflow(next={"startRecognition_2_1", "setSoundModelParameters", "unloadSoundModel"})
+    loadPhraseSoundModel_2_1(PhraseSoundModel soundModel,
+                   ISoundTriggerHwCallback callback,
+                   CallbackCookie cookie)
+            generates (int32_t retval, SoundModelHandle modelHandle);
+
+    /**
+     * Start recognition on a given model. Only one recognition active
+     * at a time per model. Once recognition succeeds of fails, the callback
+     * is called.
+     *
+     * Must have the exact same semantics as startRecognition from
+     * ISoundTriggerHw@2.0 except that the RecognitionConfig uses shared memory
+     * instead of data.
+     *
+     * @param modelHandle the handle of the sound model to use for recognition
+     * @param config A RecognitionConfig structure containing attributes of the
+     *     recognition to perform
+     * @param callback The callback interface on which the recognitionCallback()
+     *     method must be called upon recognition.
+     * @param cookie The value of the cookie argument passed to the recognition
+     *     callback. This unique context information is assigned and
+     *     used only by the framework.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid recognition attributes,
+     *     -ENOSYS in case of invalid model handle,
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     */
+    @callflow(next={"stopRecognition", "stopAllRecognitions"})
+    startRecognition_2_1(SoundModelHandle modelHandle,
+                     RecognitionConfig config,
+                     ISoundTriggerHwCallback callback,
+                     CallbackCookie cookie)
+            generates (int32_t retval);
+
+
+    struct ParameterValue {
+        string key;
+        string value;
+    };
+
+    /**
+     * Generic method for retrieving vendor-specific parameter values.
+     * The framework does not interpret the parameters, they are passed
+     * in an opaque manner between a vendor application and HAL.
+     *
+     * @param keys parameter keys.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid keys,
+     *     -ENOSYS in case if this operation is not supported,
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     * @return parameters parameter key value pairs.
+     */
+    getParameters(vec<string> keys)
+            generates (int32_t retval, vec<ParameterValue> parameters);
+
+    /**
+     * Generic method for setting vendor-specific parameter values.
+     * The framework does not interpret the parameters, they are passed
+     * in an opaque manner between a vendor application and HAL.
+     *
+     * @param parameters parameter key value pairs.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid keys,
+     *     -ENOSYS in case if this operation is not supported,
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     */
+    setParameters(vec<ParameterValue> parameters) generates (int32_t retval);
+
+    /**
+     * Generic method for retrieving vendor-specific parameter values.
+     * The framework does not interpret the parameters, they are passed
+     * in an opaque manner between a vendor application and HAL.
+     *
+     * @param modelHandle the handle of the sound model to get parameters about.
+     * @param keys parameter keys.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid keys,
+     *     -ENOSYS in case if this operation is not supported,
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     * @return parameters parameter key value pairs.
+     */
+    getSoundModelParameters(SoundModelHandle modelHandle, vec<string> keys)
+            generates (int32_t retval, vec<ParameterValue> parameters);
+
+    /**
+     * Generic method for setting vendor-specific parameter values.
+     * The framework does not interpret the parameters, they are passed
+     * in an opaque manner between a vendor application and HAL.
+     *
+     * @param modelHandle the handle of the sound model to set parameters for.
+     * @param parameters parameter key value pairs.
+     * @return retval Operation completion status: 0 in case of success,
+     *     -EINVAL in case of invalid keys,
+     *     -ENOSYS in case if this operation is not supported,
+     *     -ENOMEM in case of memory allocation failure,
+     *     -ENODEV in case of initialization error.
+     */
+    setSoundModelParameters(
+            SoundModelHandle modelHandle, vec<ParameterValue> parameters)
+            generates (int32_t retval);
+};
diff --git a/soundtrigger/2.1/ISoundTriggerHwCallback.hal b/soundtrigger/2.1/ISoundTriggerHwCallback.hal
new file mode 100644
index 0000000..42e851b
--- /dev/null
+++ b/soundtrigger/2.1/ISoundTriggerHwCallback.hal
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2017 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@2.1;
+
+import @2.0::ISoundTriggerHwCallback;
+import @2.0::PhraseRecognitionExtra;
+
+/**
+ * SoundTrigger HAL Callback interface. Obtained during SoundTrigger setup.
+ */
+@hidl_callback
+interface ISoundTriggerHwCallback extends @2.0::ISoundTriggerHwCallback {
+
+    /**
+     * Generic recognition event sent via recognition callback.
+     */
+    struct RecognitionEvent {
+        /** Event header. Any data contained in the 'header.data' field
+         * is ignored */
+        @2.0::ISoundTriggerHwCallback.RecognitionEvent header;
+        /** Opaque event data */
+        memory data;
+    };
+
+    /**
+     * Specialized recognition event for key phrase recognitions.
+     */
+    struct PhraseRecognitionEvent {
+        /** Common part of the recognition event */
+        RecognitionEvent common;
+        /** List of descriptors for each recognized key phrase */
+        vec<PhraseRecognitionExtra> phraseExtras;
+    };
+
+    /**
+     * Event sent via load sound model callback.
+     */
+    struct ModelEvent {
+        /** Event header. Any data contained in the 'header.data' field
+         * is ignored */
+        @2.0::ISoundTriggerHwCallback.ModelEvent header;
+        /** Opaque event data, passed transparently by the framework */
+        memory data;
+    };
+
+    /**
+     * Callback method called by the HAL when the sound recognition triggers.
+     *
+     * @param event A RecognitionEvent structure containing detailed results
+     *     of the recognition triggered
+     * @param cookie The cookie passed by the framework when recognition was
+     *     started (see ISoundtriggerHw.startRecognition*())
+     */
+    recognitionCallback_2_1(RecognitionEvent event, CallbackCookie cookie);
+
+    /**
+     * Callback method called by the HAL when the sound recognition triggers
+     * for a key phrase sound model.
+     *
+     * @param event A RecognitionEvent structure containing detailed results
+     *     of the recognition triggered
+     * @param cookie The cookie passed by the framework when recognition was
+     *     started (see ISoundtriggerHw.startRecognition*())
+     */
+    phraseRecognitionCallback_2_1(PhraseRecognitionEvent event,
+                                  CallbackCookie cookie);
+
+    /**
+     * Callback method called by the HAL when the sound model loading completes.
+     *
+     * @param event A ModelEvent structure containing detailed results of the
+     *     model loading operation
+     * @param cookie The cookie passed by the framework when loading was
+     *     initiated (see ISoundtriggerHw.loadSoundModel*())
+     */
+    soundModelCallback_2_1(ModelEvent event, CallbackCookie cookie);
+};