For those of you who are not familiar with IR: The electrical protocol is close to that of a UART (start, data, stop) but with the major difference that the signal is RZ (Return to Zero) and has a narrow pulse width. To forestall the question: No, there is no way to use a standard UART to receive the signal.
So you have to do the receiver in software, keeping exact track of timing of the edges. For this you want an accurate timer to read and after each edge you want to change the interrupt polarity of your GPIO input. For high baud rates you also want fast response to the interrupt otherwise the edge time your are reading is off by too much. Baseline: do-able but requiring a lot of attention to detail when you write the software.
Fist of all thanks for correcting me that ir Receiver cant be connected on Rx input of serial port .i did some reading after this replay ... and found out that LIRC project includes a GPIO interrupt driven input driver lirc_gpio(http://www.lirc.org/html/install.html
) . since we have some GPIOs available with interrupts . A IR reciever like TSOP 1738 (http://www.lirc.org/receivers.html
) can directly be connected without any other components . i am insisting on this method over USB cause it will be the cheapest and smallest. and a version of RBP can be introduce with out any change to basic design as a video player and can be sell at a higher price to produce more revenue to support the actual cause