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
0xc40000xx. The registers located at 0xc000xxxx and at 0xc800xxxx are
all accessible.

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