problem in read register status for at91rm9200 board

hi everyone
i m using the atmel at91rm9200 board on which vender has ported linux 2.6.14 and given a arm-linux-gnu-gcc compiler for cross compilation. so my question is i m accessing the pio registers like PIOB_PDSR to know the status.i m accessing it by giving the absolute address (0xfffff63c) of the register and getting the segmentation fault.so please any one tell me is this the right method to do the same or is their any other method to accessing the registers.

thanks