Re: [Xen-devel] [PATCH v8 01/17] arm: make SWIOTLB available

[Will Deacon <will.deacon@xxxxxxx>]

On Wed, Oct 09, 2013 at 09:48:14PM +0100, Stefano Stabellini wrote:
> IOMMU_HELPER is needed because SWIOTLB calls iommu_is_span_boundary,
> provided by lib/iommu_helper.c.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> CC: will.deacon@xxxxxxx
> CC: linux@xxxxxxxxxxxxxxxx

[...]

> diff --git a/arch/arm/include/asm/dma-mapping.h 
> b/arch/arm/include/asm/dma-mapping.h
> index 5b579b9..9aa5384 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -10,6 +10,7 @@
>  
>  #include <asm-generic/dma-coherent.h>
>  #include <asm/memory.h>
> +#include <asm/cacheflush.h>
>  
>  #define DMA_ERROR_CODE       (~0)
>  extern struct dma_map_ops arm_dma_ops;
> @@ -86,6 +87,42 @@ static inline dma_addr_t virt_to_dma(struct device *dev, 
> void *addr)
>  }
>  #endif
>  
> +static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
> +{
> +     unsigned int offset = paddr & ~PAGE_MASK;
> +     return pfn_to_dma(dev, paddr >> PAGE_SHIFT) + offset;

__phys_to_pfn instead of the explicit shift?

> +}
> +
> +static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t 
> dev_addr)
> +{
> +     unsigned int offset = dev_addr & ~PAGE_MASK;
> +     return (dma_to_pfn(dev, dev_addr) << PAGE_SHIFT) + offset;i

then __pfn_to_phys here.

> +}
> +
> +static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t 
> size)
> +{
> +     u64 limit, mask;
> +     
> +     if (dev->dma_mask)
> +             mask = *dev->dma_mask;
> +     else 
> +             mask = dev->coherent_dma_mask;
> +
> +     if (mask == 0)
> +             return 0;
> +
> +     limit = (mask + 1) & ~mask;

This looks like homebrew alignment to me. Can you use __ALIGN_KERNEL_MASK or
one of thoese guys from kernel.h?

Will

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