On Monday 07 April 2014 17:21:51 Bjorn Helgaas wrote: > On Fri, Mar 14, 2014 at 9:34 AM, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote: > > Some architectures do not share x86 simple view of the PCI I/O space > > and instead use a range of addresses that map to bus addresses. For > > some architectures these ranges will be expressed by OF bindings > > in a device tree file. > > > > Introduce a pci_register_io_range() helper function that can be used > > by the architecture code to keep track of the I/O ranges described by the > > PCI bindings. If the PCI_IOBASE macro is not defined that signals > > lack of support for PCI and we return an error. > > > > Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx> > > Acked-by: Grant Likely <grant.likely@xxxxxxxxxx> > > Tested-by: Tanmay Inamdar <tinamdar@xxxxxxx> > > --- > > drivers/of/address.c | 9 +++++++++ > > include/linux/of_address.h | 1 + > > 2 files changed, 10 insertions(+) > > > > diff --git a/drivers/of/address.c b/drivers/of/address.c > > index 1a54f1f..be958ed 100644 > > --- a/drivers/of/address.c > > +++ b/drivers/of/address.c > > @@ -619,6 +619,15 @@ const __be32 *of_get_address(struct device_node *dev, int index, u64 *size, > > } > > EXPORT_SYMBOL(of_get_address); > > > > +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size) > > +{ > > +#ifndef PCI_IOBASE > > + return -EINVAL; > > +#else > > + return 0; > > +#endif > > +} > > This isn't PCI code, so I'm fine with it in that sense, but I'm not > sure the idea of a PCI_IOBASE #define is really what we need. It's > not really determined by the processor architecture, it's determined > by the platform. And a single address isn't enough in general, > either, because if there are multiple host bridges, there's no reason > the apertures that generate PCI I/O transactions need to be contiguous > on the CPU side. > > That's just a long way of saying that if we ever came up with a more > generic way to handle I/O port spaces, PCI_IOBASE might go away. And > I guess part of that rework could be changing this use of it along > with the others. I'd rather not add a generic implementation of this at all, but keep it all within the host resource scanning code. If we do add a generic implementation, my preference would be to use the version introduced for arm64, with a fallback of returning -EINVAL if the architecture doesn't implement it. There is no way ever that returning '0' makes sense here: Either the architecture supports memory mapped I/O spaces and then we should be able to find an appropriate io_offset for it, or it doesn't support memory mapped I/O spaces and we should never even call this function. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html