PCI 66 MHz detection by software

Hi all

Anyone knows how a sw driver can realize that its PCI device lays on a
66 Mhz PCI segment?

The “66MHz Capable Ststus” bit 5 into the PCI Status register only says
if the device (or PCI/PCI bridge in front of the related PCI segment) is
able to work at 66 MHz clock.

It seems that only the hardware M66EN signal is available to recognize
effective operational clock, but since my device doesn’t report that
signal in a sw accessible register, I would like to know if there’s a
standard way to query the BIOS or PCI/PCI bridges configuration to know
for sure the clock frequency on a specific PCI bus segment.

Thanks in advance!

/* Ancri Davide - */