#ifndef _LINUX_IOMMU_HELPER_H
  #define _LINUX_IOMMU_HELPER_H

  #include <linux/kernel.h>

  static inline unsigned long iommu_device_max_index(unsigned long size,
  						   unsigned long offset,
  						   u64 dma_mask)
  {
  	if (size + offset > dma_mask)
  		return dma_mask - offset + 1;
  	else
  		return size;
  }

  extern int iommu_is_span_boundary(unsigned int index, unsigned int nr,
  				  unsigned long shift,
  				  unsigned long boundary_size);

  extern unsigned long iommu_area_alloc(unsigned long *map, unsigned long size,
  				      unsigned long start, unsigned int nr,
  				      unsigned long shift,
  				      unsigned long boundary_size,
  				      unsigned long align_mask);

  static inline unsigned long iommu_num_pages(unsigned long addr,
  					    unsigned long len,
  					    unsigned long io_page_size)
  {
  	unsigned long size = (addr & (io_page_size - 1)) + len;
  
  	return DIV_ROUND_UP(size, io_page_size);
  }

  #endif