diff --git a/soundtrigger/2.4/ISoundTriggerHwGlobalCallback.hal b/soundtrigger/2.4/ISoundTriggerHwGlobalCallback.hal
new file mode 100644
index 0000000..2f1a977
--- /dev/null
+++ b/soundtrigger/2.4/ISoundTriggerHwGlobalCallback.hal
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2021 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@2.4;
+
+/**
+ * SoundTrigger HAL callback interface for events not associated with a particular model.
+ */
+interface ISoundTriggerHwGlobalCallback {
+    /**
+     * Callback method called by the HAL whenever internal conditions have been made available, such
+     * that a call that would previously have failed with an -EBUSY status may now succeed.
+     * There is no guarantee that any call would succeed following this event. It is merely a hint
+     * to the client that it may retry.
+     * Conversely, any call that have failed previously with -EBUSY is guaranteed to fail again if
+     * retried, until this callback is delivered.
+     */
+    onResourcesAvailable();
+};