On Fri, 8 Aug 2014 13:23:15 -0700 Laura Abbott <lauraa@xxxxxxxxxxxxxx> wrote:
>
> For architectures without coherent DMA, memory for DMA may
> need to be remapped with coherent attributes. Factor out
> the the remapping code from arm and put it in a
> common location to reduce code duplication.
>
> As part of this, the arm APIs are now migrated away from
> ioremap_page_range to the common APIs which use map_vm_area for remapping.
> This should be an equivalent change and using map_vm_area is more
> correct as ioremap_page_range is intended to bring in io addresses
> into the cpu space and not regular kernel managed memory.
>
> ...
>
> @@ -267,3 +269,68 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> return ret;
> }
> EXPORT_SYMBOL(dma_common_mmap);
> +
> +/*
> + * remaps an allocated contiguous region into another vm_area.
> + * Cannot be used in non-sleeping contexts
> + */
> +
> +void *dma_common_contiguous_remap(struct page *page, size_t size,
> + unsigned long vm_flags,
> + pgprot_t prot, const void *caller)
> +{
> + int i;
> + struct page **pages;
> + void *ptr;
> +
> + pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
> + if (!pages)
> + return NULL;
> +
> + for (i = 0; i < (size >> PAGE_SHIFT); i++)
> + pages[i] = page + i;
Assumes a single mem_map[] array. That's not the case for sparsemem
(at least).
> + ptr = dma_common_pages_remap(pages, size, vm_flags, prot, caller);
> +
> + kfree(pages);
> +
> + return ptr;
> +}
> +
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