+int gb_control_get_firmware_version_operation(struct gb_interface *intf,
+                                             u16 *major, u16 *minor)
+{
+       struct gb_control_interface_version_response response;
+       struct gb_connection *connection = intf->control->connection;
+       int ret;
+
+       ret = gb_operation_sync(connection, GB_CONTROL_TYPE_INTERFACE_VERSION,
+                               NULL, 0, &response, sizeof(response));
+       if (ret) {
+               dev_err(&connection->intf->dev,
+                               "failed to get firmware version: %d\n", ret);
+               return ret;
+       }
+
+       *major = le16_to_cpu(response.major);
+       *minor = le16_to_cpu(response.minor);
+       dev_info(&connection->intf->dev,"%s:%x:%x:%x:%x\n", __func__, *major,
+                *minor, le16_to_cpu(response.major),
+                le16_to_cpu(response.minor));
+
+       return 0;
+}

+/* Control protocol firmware version request has no payload */
+struct gb_control_interface_version_response {
+       __le16                  major;
+       __le16                  minor;
+} __packed;


Output of the above print is:
[   35.472198] greybus 1-8: gb_control_get_firmware_version_operation:0:0:1:0