mmap to Access PCI space?

["Randall Hyde" <randyhyde@earthlink.net>]

Hi All,
I need to access a couple of SATA chips from a user-mode
program (yep, running as root). I know for a fact that my
chip resides at address 0xfc300000 (/proc/iomem and /proc/ide/siimage
tells me this).  Can I do a mmap like the following to access the registers
on ths chip?

fdDevMem = open( "/dev/mem", O_RDWR );
ptr =
    mmap
    (
        NULL,
        4096,
        PROT_READ | PROT_WRITE,
        MAP_SHARED,
        fdDevMem,
        0xfc300000
    );

When I try this, I get a valid pointer back, but it doesn't seem to
be mapped to my si3112 chip register bank.

I've also used code like the following:
ptr =
    mmap
    (
        0xfc300000,
        4096,
        PROT_READ | PROT_WRITE,
        MAP_SHARED | MAP_ANONYMOUS,
        -1,
        0
    );

Same story.
If I use MAP_FIXED and/or MAP_PRIVATE, the mmap call fails.

What am I doing wrong here?
Thanks,
Randy Hyde