diff --git a/binder/android/os/IVold.aidl b/binder/android/os/IVold.aidl
index e8a8f2a..0a05e6e 100644
--- a/binder/android/os/IVold.aidl
+++ b/binder/android/os/IVold.aidl
@@ -16,8 +16,12 @@
 
 package android.os;
 
+import android.os.IVoldListener;
+
 /** {@hide} */
 interface IVold {
+    void setListener(IVoldListener listener);
+
     void reset();
     void shutdown();
     void mountAll();
@@ -116,19 +120,19 @@
     const int REMOUNT_MODE_READ = 2;
     const int REMOUNT_MODE_WRITE = 3;
 
-    const int STATE_UNMOUNTED = 0;
-    const int STATE_CHECKING = 1;
-    const int STATE_MOUNTED = 2;
-    const int STATE_MOUNTED_READ_ONLY = 3;
-    const int STATE_FORMATTING = 4;
-    const int STATE_EJECTING = 5;
-    const int STATE_UNMOUNTABLE = 6;
-    const int STATE_REMOVED = 7;
-    const int STATE_BAD_REMOVAL = 8;
+    const int VOLUME_STATE_UNMOUNTED = 0;
+    const int VOLUME_STATE_CHECKING = 1;
+    const int VOLUME_STATE_MOUNTED = 2;
+    const int VOLUME_STATE_MOUNTED_READ_ONLY = 3;
+    const int VOLUME_STATE_FORMATTING = 4;
+    const int VOLUME_STATE_EJECTING = 5;
+    const int VOLUME_STATE_UNMOUNTABLE = 6;
+    const int VOLUME_STATE_REMOVED = 7;
+    const int VOLUME_STATE_BAD_REMOVAL = 8;
 
-    const int TYPE_PUBLIC = 0;
-    const int TYPE_PRIVATE = 1;
-    const int TYPE_EMULATED = 2;
-    const int TYPE_ASEC = 3;
-    const int TYPE_OBB = 4;
+    const int VOLUME_TYPE_PUBLIC = 0;
+    const int VOLUME_TYPE_PRIVATE = 1;
+    const int VOLUME_TYPE_EMULATED = 2;
+    const int VOLUME_TYPE_ASEC = 3;
+    const int VOLUME_TYPE_OBB = 4;
 }
diff --git a/binder/android/os/IVoldListener.aidl b/binder/android/os/IVoldListener.aidl
new file mode 100644
index 0000000..0dcfc04
--- /dev/null
+++ b/binder/android/os/IVoldListener.aidl
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 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.os;
+
+/** {@hide} */
+oneway interface IVoldListener {
+    void onDiskCreated(@utf8InCpp String diskId, int flags);
+    void onDiskScanned(@utf8InCpp String diskId);
+    void onDiskMetadataChanged(@utf8InCpp String diskId,
+            long sizeBytes, @utf8InCpp String label, @utf8InCpp String sysPath);
+    void onDiskDestroyed(@utf8InCpp String diskId);
+
+    void onVolumeCreated(@utf8InCpp String volId,
+            int type, @utf8InCpp String diskId, @utf8InCpp String partGuid);
+    void onVolumeStateChanged(@utf8InCpp String volId, int state);
+    void onVolumeMetadataChanged(@utf8InCpp String volId,
+            @utf8InCpp String fsType, @utf8InCpp String fsUuid, @utf8InCpp String fsLabel);
+    void onVolumePathChanged(@utf8InCpp String volId,
+            @utf8InCpp String path);
+    void onVolumeInternalPathChanged(@utf8InCpp String volId,
+            @utf8InCpp String internalPath);
+    void onVolumeDestroyed(@utf8InCpp String volId);
+}