On 10/8/13, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote:
> On Tue, Oct 08, 2013 at 05:32:57PM +0100, Bjorn Helgaas wrote:
>> [+cc Grant, Rob, devicetree list]
>>
>> On Tue, Oct 8, 2013 at 8:42 AM, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote:
>> > Hello,
>> >
>> > I am working on adding PCIe support for a new architecture and looking
>> > at various existing implementations of pcibios functions I've realised
>> > that some architectures share a lot of common code. As I don't like to
>> > repeat the pattern again without any good reasons, I am wondering if
>> > there is any appetite for carving out those common functions into
>> > a generic place under drivers/pci/pcibios.c where they can be reused.
>> >
>> > Things that I am specifically looking at are
>> > pcibios_{alloc,free}_controller,
>> > pci_process_bridge_OF_ranges and anything that will make adding support
>> > for PCI/PCIe in a new architecture easier. Candidates for promoting
>> > to a generic place are the functions found in both powerpc and
>> > microblaze
>> > as they seem to be mostly identical, they support DT bindings and are
>> > 64bits ready.
>>
>> I'm very much in favor of unifying code to reduce duplication across
>> architectures.
>>
>> In general, the pcibios_*() interfaces are things used by the PCI core
>> (drivers/pci) but implemented by the architecture. The specific cases
>> you mentioned are not actually used by the PCI core, so my inclination
>> would be to name them something else and possibly put them somewhere
>> other than drivers/pci.
>
> There are at least a handful of architectures that seem to share the same
> implementation for most (all?) of the pcibios_*() functions. (PowerPC and
> microblaze the most obvious offenders, x86 to a certain extent).
Yes. We've unified some of these by putting the generic version in
drivers/pci as a weak function.
>> I wonder if pci_process_bridge_OF_ranges() would fit somewhere in
>> drivers/of? The implementations I looked at are mostly concerned with
>> parsing OF resources, and they don't have much to do with PCI
>> directly.
>
> Andrew Murray did sent a patch that was placing
> pci_process_bridge_OF_ranges()
> in the drivers/of. I can update that, as I have taken over his work.
>
>>
>> pcibios_alloc_controller() is implemented by microblaze, powerpc, and
>> xtensa. Each of those arches defines its own "struct pci_controller",
>> so it won't be completely trivial to unify this. I tried to start
>> some unification with the "struct pci_host_bridge" in the core, but
>> haven't made much progress there.
>
> Do you have anything that you could share? I would pretty much like to take
> on that as well, as I don't want to create yet another
> "struct pci_controller." BTW, powerpc and microblaze again share a very
> similarly looking structure.
No, I don't have any code (or plans). I think pci_domain_nr() and
pcibus_to_node() should be pretty easy to start unifying. I'd be
thrilled if you started pushing on this.
Bjorn
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