static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
	    dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs)
{
	pgprot_t prot = __get_dma_pgprot(attrs, pgprot_kernel);
	struct page **pages;
	void *addr = NULL;

	*handle = DMA_ERROR_CODE;
	size = PAGE_ALIGN(size);

	if (gfp & GFP_ATOMIC)
		return __iommu_alloc_atomic(dev, size, handle);

	/*
	 * Following is a work-around (a.k.a. hack) to prevent pages
	 * with __GFP_COMP being passed to split_page() which cannot
	 * handle them.  The real problem is that this flag probably
	 * should be 0 on ARM as it is not supported on this
	 * platform; see CONFIG_HUGETLBFS.
	 */
	gfp &= ~(__GFP_COMP);

	pages = __iommu_alloc_buffer(dev, size, gfp, attrs);
	if (!pages)
		return NULL;

	*handle = __iommu_create_mapping(dev, pages, size);
	if (*handle == DMA_ERROR_CODE)
		goto err_buffer;

	if (dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs))
		return pages;

	addr = __iommu_alloc_remap(pages, size, gfp, prot,
				   __builtin_return_address(0));
	if (!addr)
		goto err_mapping;

	return addr;

err_mapping:
	__iommu_remove_mapping(dev, *handle, size);
err_buffer:
	__iommu_free_buffer(dev, pages, size, attrs);
	return NULL;
}
static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
	    dma_addr_t *handle, gfp_t gfp, struct dma_attrs *attrs)
{
	pgprot_t prot = __get_dma_pgprot(attrs, pgprot_kernel);
	struct page **pages;
	void *addr = NULL;

	*handle = DMA_ERROR_CODE;
	size = PAGE_ALIGN(size);

	if (gfp & GFP_ATOMIC)
		return __iommu_alloc_atomic(dev, size, handle);

	 
	gfp &= ~(__GFP_COMP);

	pages = __iommu_alloc_buffer(dev, size, gfp, attrs);
	if (!pages)
		return NULL;

	*handle = __iommu_create_mapping(dev, pages, size);
	if (*handle == DMA_ERROR_CODE)
		goto err_buffer;

	if (dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs))
		return pages;

	addr = __iommu_alloc_remap(pages, size, gfp, prot,
				   __builtin_return_address(0));
	if (!addr)
		goto err_mapping;

	return addr;

err_mapping:
	__iommu_remove_mapping(dev, *handle, size);
err_buffer:
	__iommu_free_buffer(dev, pages, size, attrs);
	return NULL;
}