Index: uspace/lib/drv/generic/private/remote_usbdiag.h
===================================================================
--- uspace/lib/drv/generic/private/remote_usbdiag.h	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
+++ uspace/lib/drv/generic/private/remote_usbdiag.h	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2017 Petr Manek
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libdrv
+* @{
+*/
+/** @file
+*/
+
+#ifndef LIBDRV_REMOTE_USBDIAG_H_
+#define LIBDRV_REMOTE_USBDIAG_H_
+
+extern remote_iface_t remote_usbdiag_iface;
+
+#endif
+
+/**
+* @}
+*/
Index: uspace/lib/drv/generic/remote_usbdiag.c
===================================================================
--- uspace/lib/drv/generic/remote_usbdiag.c	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
+++ uspace/lib/drv/generic/remote_usbdiag.c	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017 Petr Manek
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libdrv
+ * @{
+ */
+/** @file
+ * USB diagnostic device remote interface.
+ */
+
+#include <async.h>
+#include <assert.h>
+#include <macros.h>
+#include <errno.h>
+#include <devman.h>
+
+#include "usbdiag_iface.h"
+
+typedef enum {
+	IPC_M_USBDIAG_TEST,
+} usb_iface_funcs_t;
+
+async_sess_t *usbdiag_connect(devman_handle_t handle)
+{
+	return devman_device_connect(handle, IPC_FLAG_BLOCKING);
+}
+
+void usbdiag_disconnect(async_sess_t *sess)
+{
+	if (sess)
+		async_hangup(sess);
+}
+
+int usbdiag_test(async_exch_t *exch, int x, int *y)
+{
+	if (!exch)
+		return EBADMEM;
+
+	sysarg_t y_;
+	const int ret = async_req_2_1(exch, DEV_IFACE_ID(USBDIAG_DEV_IFACE), IPC_M_USBDIAG_TEST, x, &y_);
+
+	if (y)
+		*y = (int) y_;
+
+	return ret;
+}
+
+static void remote_usbdiag_test(ddf_fun_t *, void *, ipc_callid_t, ipc_call_t *);
+
+/** Remote USB diagnostic interface operations. */
+static const remote_iface_func_ptr_t remote_usbdiag_iface_ops [] = {
+	[IPC_M_USBDIAG_TEST] = remote_usbdiag_test,
+};
+
+/** Remote USB diagnostic interface structure. */
+const remote_iface_t remote_usbdiag_iface = {
+	.method_count = ARRAY_SIZE(remote_usbdiag_iface_ops),
+	.methods = remote_usbdiag_iface_ops,
+};
+
+void remote_usbdiag_test(ddf_fun_t *fun, void *iface, ipc_callid_t callid, ipc_call_t *call)
+{
+	const usbdiag_iface_t *diag_iface = (usbdiag_iface_t *) iface;
+
+	if (diag_iface->test == NULL) {
+		async_answer_0(callid, ENOTSUP);
+		return;
+	}
+
+	int x = DEV_IPC_GET_ARG1(*call);
+	int y;
+	const int ret = diag_iface->test(fun, x, &y);
+	if (ret != EOK) {
+		async_answer_0(callid, ret);
+	} else {
+		async_answer_1(callid, EOK, y);
+	}
+}
+
+/**
+ * @}
+ */
Index: uspace/lib/drv/include/usbdiag_iface.h
===================================================================
--- uspace/lib/drv/include/usbdiag_iface.h	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
+++ uspace/lib/drv/include/usbdiag_iface.h	(revision 32fb6bcec95f3a7fbb1b2fdb6528f0e04726a6b6)
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2017 Petr Manek
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libdrv
+* @addtogroup usb
+* @{
+*/
+/** @file
+* @brief USB diagnostic device interface definition.
+*/
+
+#ifndef LIBDRV_USBDIAG_IFACE_H_
+#define LIBDRV_USBDIAG_IFACE_H_
+
+#include <async.h>
+#include "ddf/driver.h"
+
+#define USBDIAG_CATEGORY "usbdiag"
+
+async_sess_t *usbdiag_connect(devman_handle_t);
+void usbdiag_disconnect(async_sess_t*);
+int usbdiag_test(async_exch_t*, int, int*);
+
+/** USB diagnostic device communication interface. */
+typedef struct {
+	int (*test)(ddf_fun_t*, int, int*);
+} usbdiag_iface_t;
+
+#endif
+/**
+ * @}
+ */