title: Pin Muxing in linux kernel
body: <p>I want to do following pin muxing.
  i.e USART Tx -> to GPIO -> Back to USART Tx pin inside Linux kernel for some purpose.</p>
  
  <p>I tried to make the PIN as GPIO using gpio_request and gpio_direction_output, so i am able to make that pin as GPIO . But as i want to switch back from GPIO to USART Tx pin, it is not working, I tried following at91_set_A_periph to that pin, still no luck.</p>
  
  <p>Working on kernel : 3.18 and at91 atmel board.</p>