title: Linux tool to send a SET_CONFIGURATION message to a device connected to the USB bus
body: <p>I have developed a kernel driver for a USB device. Such a device has some pins that can provide functionality both as CDC ACM serial port or as input buttons. So to implement that I had to use two different USB configuration descriptors.</p>
  
  <p>The driver works as expected, but I have to hardcode the chosen setup before compiling and loading the firmware to the micro-controller. I am searching a mechanism to change that device configuration from userspace.</p>
  
  <p>I read about a SET_CONFIGURATION message on USB documentation, but coudn't find any Linux tool to send such kind of standard USB messages from userspace to the USB bus.</p>
  
  <p>Does some of you (with more experience on this topic) know some userspace Linux tool to send a SET_CONFIGURATION message to a device connected to the USB bus?</p>
  
  <p>Thanks in advance! :)</p>