On Thu, Sep 18, 2014 at 02:30:25AM +0100, Liviu Dudau wrote:
> Introduce a default implementation for remapping PCI bus I/O resources
> onto the CPU address space. Architectures with special needs may
> provide their own version, but most should be able to use this one.
I see that this is used by Tanmay's APM X-Gene PCIe host controller driver.
Since it's not used in this series, it'd be nice to mention where it *will*
be used.
> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
> ---
> drivers/pci/pci.c | 33 +++++++++++++++++++++++++++++++++
> include/asm-generic/pgtable.h | 4 ++++
> include/linux/pci.h | 3 +++
> 3 files changed, 40 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 2c9ac70..654b44c 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2704,6 +2704,39 @@ int pci_request_regions_exclusive(struct pci_dev *pdev, const char *res_name)
> }
> EXPORT_SYMBOL(pci_request_regions_exclusive);
>
> +/**
> + * pci_remap_iospace - Remap the memory mapped I/O space
> + * @res: Resource describing the I/O space
> + * @phys_addr: physical address where the range will be mapped.
> + *
> + * Remap the memory mapped I/O space described by the @res
> + * into the CPU physical address space.
This comment doesn't seem quite right. I think the space is already in the
CPU physical address space. ioremap() and friends normally map existing
physical space into the *virtual* address space, i.e., they create mappings
from a virtual address to a physical address.
> Only architectures
> + * that have memory mapped IO defined (and hence PCI_IOBASE)
> + * should call this function.
> + */
> +int __weak pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr)
> +{
> + int err = -ENODEV;
> +
> +#ifdef PCI_IOBASE
> + if (!(res->flags & IORESOURCE_IO))
> + return -EINVAL;
> +
> + if (res->end > IO_SPACE_LIMIT)
> + return -EINVAL;
> +
PCI_IOBASE is a virtual address. So PCI_IOBASE + res->start is also a
virtual address (only for IORESOURCE_IO).
Since res->start is normally a *physical* address, I think it would be less
confusing to do something like this:
vaddr = PCI_IOBASE + res->start;
ioremap_page_range(vaddr, vaddr + resource_size(res), ...);
so we have a hint that the first two ioremap_page_range() parameters are
virtual addresses. It's also confusing that it uses "unsigned long" for
the virtual addresses, when we usually use "void *". But that's out of
scope for this patch.
> + err = ioremap_page_range(res->start + (unsigned long)PCI_IOBASE,
> + res->end + 1 + (unsigned long)PCI_IOBASE,
> + phys_addr, pgprot_device(PAGE_KERNEL));
> +#else
> + /* this architecture does not have memory mapped I/O space,
> + so this function should never be called */
> + WARN_ON(1);
> +#endif
> +
> + return err;
> +}
> +
> static void __pci_set_master(struct pci_dev *dev, bool enable)
> {
> u16 old_cmd, cmd;
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 53b2acc..977e545 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -249,6 +249,10 @@ static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
> #define pgprot_writecombine pgprot_noncached
> #endif
>
> +#ifndef pgprot_device
> +#define pgprot_device pgprot_noncached
> +#endif
> +
> /*
> * When walking page tables, get the address of the next boundary,
> * or the end address of the range if that comes earlier. Although no
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index a494e5d..fc8c529 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1100,6 +1100,9 @@ int __must_check pci_bus_alloc_resource(struct pci_bus *bus,
> resource_size_t),
> void *alignf_data);
>
> +
> +int pci_remap_iospace(const struct resource *res, phys_addr_t phys_addr);
> +
> static inline dma_addr_t pci_bus_address(struct pci_dev *pdev, int bar)
> {
> struct pci_bus_region region;
> --
> 2.1.0
>
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