RE: bare pci configuration access functions ?

[Kai Germaschewski]

On Thu, 31 Oct 2002, Grover, Andrew wrote:

> > From: Lee, Jung-Ik [mailto:[e-mail]] 
> > 	Some kernel drivers/components such as hotplug 
> > pci/io-node drivers,
> > ACPI driver, some console drivers, etc **need bare pci 
> > configuration space
> > access** before either pci driver is initialized or struct pci_dev is
> > constructed.
> > 
> > ACPI needs this for ACPI/PCI population, hotplug pci driver 
> > for populating
> > hot-added pci hierarchy. As more drivers are cross ported 
> > over to wider
> > architectures, this would become wider need. Help me if 
> > others need this
> > too.
> 
> When the PCI Config stuff got revamped a few months ago, Greg KH, myself,
> and some other people discussed this, and the conclusion seemed to be that
> it was less ugly to make the code that needs bare PCI config access use fake
> structs, than to have the bare functions exposed. Greg, am I remembering
> correctly?

As one of the other people involved, I think the solution which was agreed
on was to have the lower level functions provided with (struct pci_bus *,
u8 dev, u8 fn) since that is what's really needed to implement the config
accesses. The standard PCI config functions, taking struct pci_dev * are
merely a wrapper around these. Greg did a patch to implement it, and it
looks like it got merged.

pci_bus_{read,write}_config_{byte,word,dword}()

--Kai