Re: [Xen-devel] [PATCH] swiotlb-xen: implement xen_swiotlb_dma_mmap callback

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 7 Apr 2014, Oleksandr Dmytryshyn wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> This function creates userspace mapping for the DMA-coherent memory.
> 
> Change-Id: If22f75996278063394f628f57869ccd3ca09de7c
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>

Much better, thank you.
Given that Xen needs MMU support I think we can safely get rid of the
ifdef CONFIG_MMU.


>  arch/arm/xen/mm.c         |  1 +
>  drivers/xen/swiotlb-xen.c | 36 ++++++++++++++++++++++++++++++++++++
>  include/xen/swiotlb-xen.h |  5 +++++
>  3 files changed, 42 insertions(+)
> 
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index b0e77de..91408b1 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -48,6 +48,7 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
>       .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
>       .map_sg = xen_swiotlb_map_sg_attrs,
>       .unmap_sg = xen_swiotlb_unmap_sg_attrs,
> +     .mmap = xen_swiotlb_dma_mmap,
>       .map_page = xen_swiotlb_map_page,
>       .unmap_page = xen_swiotlb_unmap_page,
>       .dma_supported = xen_swiotlb_dma_supported,
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 5403855..acf0c06 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -407,6 +407,42 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, 
> struct page *page,
>  EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
>  
>  /*
> + * Create userspace mapping for the DMA-coherent memory.
> + */
> +int xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> +                      void *cpu_addr, dma_addr_t dma_addr, size_t size,
> +                      struct dma_attrs *attrs)
> +{
> +     int ret = -ENXIO;
> +#ifdef CONFIG_MMU
> +     unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> 
> PAGE_SHIFT;
> +     unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> +     unsigned long pfn = PFN_DOWN(xen_bus_to_phys(dma_addr));
> +     unsigned long off = vma->vm_pgoff;
> +     pgprot_t prot = vma->vm_page_prot;
> +
> +     prot = dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs) ?
> +                         pgprot_writecombine(prot) :
> +                         pgprot_dmacoherent(prot);
> +
> +     vma->vm_page_prot = prot;
> +
> +     if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> +             return ret;
> +
> +     if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
> +             ret = remap_pfn_range(vma, vma->vm_start,
> +                                     pfn + off,
> +                                     vma->vm_end - vma->vm_start,
> +                                     vma->vm_page_prot);
> +     }
> +#endif  /* CONFIG_MMU */
> +
> +     return ret;
> +}
> +EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
> +
> +/*
>   * Unmap a single streaming mode DMA translation.  The dma_addr and size must
>   * match what was provided for in a previous xen_swiotlb_map_page call.  All
>   * other usages are undefined.
> diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> index 7b64465..930fa94 100644
> --- a/include/xen/swiotlb-xen.h
> +++ b/include/xen/swiotlb-xen.h
> @@ -15,6 +15,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t 
> size,
>                         void *vaddr, dma_addr_t dma_handle,
>                         struct dma_attrs *attrs);
>  
> +extern int
> +xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> +                  void *cpu_addr, dma_addr_t dma_addr, size_t size,
> +                  struct dma_attrs *attrs);
> +
>  extern dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
>                                      unsigned long offset, size_t size,
>                                      enum dma_data_direction dir,
> -- 
> 1.8.2.rc2
> 

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