int arm_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 = dma_to_pfn(dev, dma_addr);
	unsigned long off = vma->vm_pgoff;

	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_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;
}
int arm_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 = dma_to_pfn(dev, dma_addr);
	unsigned long off = vma->vm_pgoff;

	vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_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	 

	return ret;
}