--- /dev/null
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * USB CDC Device Management userspace API definitions
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_USB_CDC_WDM_H
+#define __LINUX_USB_CDC_WDM_H
+
+#include <linux/types.h>
+
+/*
+ * This IOCTL is used to retrieve the wMaxCommand for the device,
+ * defining the message limit for both reading and writing.
+ *
+ * For CDC WDM functions this will be the wMaxCommand field of the
+ * Device Management Functional Descriptor.
+ */
+#define IOCTL_WDM_MAX_COMMAND _IOR('H', 0xA0, __u16)
+
+#endif /* __LINUX_USB_CDC_WDM_H */