PCI reset using x86 or x86-64 BIOS calls?

[linas@austin.ibm.com (Linas Vepstas)]

I've go a newbie x86 BIOS question:  is there a BIOS function that 
can be called to reset a PCI device? (By "reset a device" I mean
raise the #RST PCI signal line to electrical high for 1.5 seconds).
I know that BIOS does this during a soft reboot, but I was wondering
if there's a stand-alone function for doing this while the system is up
and running.

This question ame up during conversations about kexec. When kexec is
used to get out from under a crashed system, the PCI devices are 
typically in some unknown state, and need to be brought to heel. 
It seems to me that a brute-force reset would be a particularly 
straightforward way of doing this.

--linas