v4.19.13 snapshot.
diff --git a/include/linux/sound.h b/include/linux/sound.h
new file mode 100644
index 0000000..ec85b7a
--- /dev/null
+++ b/include/linux/sound.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SOUND_H
+#define _LINUX_SOUND_H
+
+#include <uapi/linux/sound.h>
+
+/*
+ * Sound core interface functions
+ */
+
+struct device;
+extern int register_sound_special(const struct file_operations *fops, int unit);
+extern int register_sound_special_device(const struct file_operations *fops, int unit, struct device *dev);
+extern int register_sound_mixer(const struct file_operations *fops, int dev);
+extern int register_sound_dsp(const struct file_operations *fops, int dev);
+
+extern void unregister_sound_special(int unit);
+extern void unregister_sound_mixer(int unit);
+extern void unregister_sound_dsp(int unit);
+#endif /* _LINUX_SOUND_H */