2012/12/7 Arnd Bergmann <arnd@xxxxxxxx>: > On Friday 07 December 2012, Michal Simek wrote: >> On 12/06/2012 10:27 PM, Bjorn Helgaas wrote: >> > [+cc linux-pci] >> > >> > On Thu, Dec 6, 2012 at 7:23 AM, Michal Simek <michal.simek@xxxxxxxxxx> wrote: >> >> Hi guys, >> >> >> >> I have a question regarding to sharing generic OF pcie driver between >> >> two architectures MB and ARM Zynq. >> >> Is drivers/pci/pcie location good for it? >> >> Make no sense to have the same driver in two locations. >> > >> > I think you're talking about a PCI host bridge driver. It would >> > definitely be nice to move toward a generic, shared driver. Host >> > bridge drivers are responsible for enumerating the PCI hierarchy below >> > the bridge. Enumeration is not really PCIe-specific, so I wouldn't >> > put it in drivers/pci/pcie. >> >> Not a PCI expert, just trying to find out the proper location for this shared driver. > > I'd suggest creating a drivers/pci/host directory. We will have more of > these in the future. AFAIK, there is no fully generic (architecture > independent) way to interface a PCI host driver to the PCI subsystem, > but I think we are getting closer to that. You are probably fairly > free to modify the microblaze architecture specific code though if needed. yep. >> >> Is using readl/writel IO functions in this driver the best option >> >> which we can have? >> >> Or is there any other recommendation? >> > >> > I'm not really a driver person, but if you're writing a new driver, >> > wouldn't you use the iomap interfaces (ioremap(), ioread32(), etc) >> > rather than readl()? >> >> That driver exists but it is not in mainline and it is better to directly >> add it to proper location with correct io functions. >> The question is if ioread/iowrite functions are correct one. >> PowerPC io-defs.h suggests that readl/writel should be used for PCI. > > ioread32/iowrite32 are defined to behave the same way readl/writel regarding > addressing modes and barriers, but also allow operating on __iomem pointers > that were returned from ioport_map(). You probably don't need that. > > Some architectures like powerpc have their own accessors for on-chip MMIO > areas, but ARM does not. The PowerPC rule is that you must use either > readl/writel or ioread32/iowrite32 to access devices connected to a PCI > bus, but you would not necessarily do that for the PCI host controller > itself on PowerPC. ok. Thanks, Michal -- Michal Simek, Ing. (M.Eng) w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/ Microblaze U-BOOT custodian -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
