Re: [PATCH v2 1/4] arm64: enable pci resource mapping using sysfs

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc linux-pci]

On Wed, Mar 15, 2017 at 08:42:20PM +0000, David Woodhouse wrote:
> From: Brijesh Singh <brijess@amazon.com>
> 
> To support PCI resource mapping from userspace, pci_mmap_page_range()
> must be implemented and HAVE_PCI_MMAP defined. This support was absent
> for arm64.
> 
> [dwmw2: Add WC support]
> Reviewed-by: Erik Quanstrom <quanstro@amazon.com>
> Reviewed-by: Anthony Liguori <aliguori@amazon.com>
> Signed-off-by: Brijesh Singh <brijess@amazon.com>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> v2: s/pgprot_uncached/pgprot_device/
> 
>  arch/arm64/include/asm/pci.h |  4 ++++
>  arch/arm64/kernel/pci.c      | 19 +++++++++++++++++++
>  2 files changed, 23 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> index b9a7ba9..f73734f 100644
> --- a/arch/arm64/include/asm/pci.h
> +++ b/arch/arm64/include/asm/pci.h
> @@ -37,5 +37,9 @@ static inline int pci_proc_domain(struct pci_bus *bus)
>  }
>  #endif  /* CONFIG_PCI */
>  
> +#define HAVE_PCI_MMAP
> +extern int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> +			       enum pci_mmap_state mmap_state, int write_combine);
> +
>  #endif  /* __KERNEL__ */
>  #endif  /* __ASM_PCI_H */
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 4f0e3eb..9a87b2a 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -228,3 +228,22 @@ void pcibios_remove_bus(struct pci_bus *bus)
>  }
>  
>  #endif
> +
> +int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> +			enum pci_mmap_state mmap_state, int write_combine)
> +{
> +	if (mmap_state == pci_mmap_io)
> +		return -EINVAL;
> +
> +	if (write_combine)
> +		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
> +	else
> +		vma->vm_page_prot = pgprot_device(vma->vm_page_prot);
> +
> +	if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
> +			     vma->vm_end - vma->vm_start,
> +			     vma->vm_page_prot))
> +		return -EAGAIN;
> +
> +	return 0;
> +}
> -- 
> dwmw2



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