linux-kernel - Re: [PATCH] ARM64/PCI: Allow userspace to mmap PCI resources

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Date:   Wed, 3 May 2017 16:58:58 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Bharat Bhushan <Bharat.Bhushan@....com>
Cc:     catalin.marinas@....com, will.deacon@....com, bhelgaas@...gle.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM64/PCI: Allow userspace to mmap PCI resources

On Wed, May 03, 2017 at 09:18:58PM +0530, Bharat Bhushan wrote:
> This patch allows user-space to mmap PCI resources. This
> patch is inline to arm32 bit implementation.
> 
> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@....com>
> ---
>  arch/arm64/include/asm/pci.h |  4 ++++
>  arch/arm64/kernel/pci.c      | 19 +++++++++++++++++++
>  2 files changed, 23 insertions(+)

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/arch/arm64/include/asm/pci.h?id=f719582435afe9c7985206e42d804ea6aa315d33

> 
> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
> index b9a7ba9..8a18915 100644
> --- a/arch/arm64/include/asm/pci.h
> +++ b/arch/arm64/include/asm/pci.h
> @@ -31,6 +31,10 @@ static inline int pci_get_legacy_ide_irq(struct pci_dev *dev, int channel)
>  	return -ENODEV;
>  }
>  
> +#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);
>  static inline int pci_proc_domain(struct pci_bus *bus)
>  {
>  	return 1;
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index ce20f4c..2e45a83 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -97,6 +97,25 @@ int pcibios_check_service_irqs(struct pci_dev *dev, int *irqs, int mask)
>  	return count;
>  }
>  
> +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;
> +
> +	/*
> +	 * Mark this as IO
> +	 */
> +	vma->vm_page_prot = pgprot_noncached(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;
> +}
> +
>  /*
>   * raw_pci_read/write - Platform-specific PCI config space access.
>   */
> -- 
> 1.9.3
>