problem accessing expansion bus registers on IXP425

I have an XSCALE IXP425 board and for some unknown reason, I have not been able to access any of the expansion bus config registers at

I checked the MMU mapping in hal_platform_setup.h and the expansion bus config register space is configured in the same way as the other config registers on the processor. They all occupy 1 Meg of space. So it looks OK.

Does the EXP_CLK which is fed by GPIO15 need to be running for the expansion bus config registers to work? Based on the setting in the GPCLKR, GPIO15 is set to run at 33MHz at 50% duty cycle.

My flash memory is on EXP_CS0 chip select, and it runs fine. I can read the flash memory space at 0x50000000 OK. But I have a serial device on CS 1 and 2, and I cannot access it at all.

Anyone out there experienced the same problem as I have? Please help.

Thanks