Subject: [PATCH v2] arm64: pci: add support for pci_mmap_page_range

From: [email-masked] (Will Deacon)
Date: Fri, 15 Apr 2016 14:09:53 +0100

On Thu, Apr 14, 2016 at 02:40:56AM +0530, Jerin Jacob wrote:
> Certain X11 servers and user space network drivers frameworks
> need PCI mmaped /sys/bus/pci/devices/B:D:F/resourceX file to
> access PCI bar address space from user space.
> 
> Signed-off-by: Jerin Jacob <[email-masked]>
> ---
> Changes in v2:
>   - Rebased to 4.6.0-rc3.
>   - Tested and verified the change on Thunderx and xgene1 arm64 platforms
> 
>  arch/arm64/include/asm/pci.h |  6 ++++++
>  arch/arm64/kernel/pci.c      | 20 ++++++++++++++++++++
>  2 files changed, 26 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> index b9a7ba9..9d7e460 100644
> --- a/arch/arm64/include/asm/pci.h
> +++ b/arch/arm64/include/asm/pci.h
> @@ -37,5 +37,11 @@ static inline int pci_proc_domain(struct pci_bus *bus)
>  }
>  #endif  /* CONFIG_PCI */
>  
> +#define HAVE_PCI_MMAP

By defining this symbol, we also get lumbered with the legacy /proc
interface, which I'd be keen to avoid exposing until we have people
explicitly asking for it.

Any chance you could expose only the /sysfs interface on arm64?

> +
> +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 c72de66..be7ddf1 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -82,3 +82,23 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  	return NULL;
>  }
>  #endif
> +
> +int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
> +		enum pci_mmap_state mmap_state, int write_combine)
> +{
> +	/*
> +	* I/O space can be accessed via normal processor loads and stores on
> +	* this platform but for now we elect not to do this and portable
> +	* drivers should not do this anyway.
> +	*/
> +	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_noncached(vma->vm_page_prot);

For consistency with ioremap, this should be pgprot_device.

Will