Physical memory access from kld

[M. Warner Losh]

I think that you'll want to use PCIB_READ_CONFIG.  This function takes
a pointer to a pci bridge device_t and can be used to read an
arbitrary register in pci config space.

PCIB_READ_CONFIG(pcib, b, s, f, n, w)

b -- bus
s -- slot
f -- function
n -- register to read
w -- width to read

This will help you access device on bus 0, slot 6, function 0.  It
will access the actual hardware, not the cached values like you have
been doing in 4.x.  Hope this helps.

Warner