text: #ifndef _ASM_GENERIC_DMA_MAPPING_H
  #define _ASM_GENERIC_DMA_MAPPING_H
  
  #include <linux/kmemcheck.h>
  #include <linux/bug.h>
  #include <linux/scatterlist.h>
  #include <linux/dma-debug.h>
  #include <linux/dma-attrs.h>
  
  static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
  					      size_t size,
  					      enum dma_data_direction dir,
  					      struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  	dma_addr_t addr;
  
  	kmemcheck_mark_initialized(ptr, size);
  	BUG_ON(!valid_dma_direction(dir));
  	addr = ops->map_page(dev, virt_to_page(ptr),
  			     (unsigned long)ptr & ~PAGE_MASK, size,
  			     dir, attrs);
  	debug_dma_map_page(dev, virt_to_page(ptr),
  			   (unsigned long)ptr & ~PAGE_MASK, size,
  			   dir, addr, true);
  	return addr;
  }
  
  static inline void dma_unmap_single_attrs(struct device *dev, dma_addr_t addr,
  					  size_t size,
  					  enum dma_data_direction dir,
  					  struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->unmap_page)
  		ops->unmap_page(dev, addr, size, dir, attrs);
  	debug_dma_unmap_page(dev, addr, size, dir, true);
  }
  
  static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
  				   int nents, enum dma_data_direction dir,
  				   struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  	int i, ents;
  	struct scatterlist *s;
  
  	for_each_sg(sg, s, nents, i)
  		kmemcheck_mark_initialized(sg_virt(s), s->length);
  	BUG_ON(!valid_dma_direction(dir));
  	ents = ops->map_sg(dev, sg, nents, dir, attrs);
  	debug_dma_map_sg(dev, sg, nents, ents, dir);
  
  	return ents;
  }
  
  static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
  				      int nents, enum dma_data_direction dir,
  				      struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	debug_dma_unmap_sg(dev, sg, nents, dir);
  	if (ops->unmap_sg)
  		ops->unmap_sg(dev, sg, nents, dir, attrs);
  }
  
  static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
  				      size_t offset, size_t size,
  				      enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  	dma_addr_t addr;
  
  	kmemcheck_mark_initialized(page_address(page) + offset, size);
  	BUG_ON(!valid_dma_direction(dir));
  	addr = ops->map_page(dev, page, offset, size, dir, NULL);
  	debug_dma_map_page(dev, page, offset, size, dir, addr, false);
  
  	return addr;
  }
  
  static inline void dma_unmap_page(struct device *dev, dma_addr_t addr,
  				  size_t size, enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->unmap_page)
  		ops->unmap_page(dev, addr, size, dir, NULL);
  	debug_dma_unmap_page(dev, addr, size, dir, false);
  }
  
  static inline void dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr,
  					   size_t size,
  					   enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_single_for_cpu)
  		ops->sync_single_for_cpu(dev, addr, size, dir);
  	debug_dma_sync_single_for_cpu(dev, addr, size, dir);
  }
  
  static inline void dma_sync_single_for_device(struct device *dev,
  					      dma_addr_t addr, size_t size,
  					      enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_single_for_device)
  		ops->sync_single_for_device(dev, addr, size, dir);
  	debug_dma_sync_single_for_device(dev, addr, size, dir);
  }
  
  static inline void dma_sync_single_range_for_cpu(struct device *dev,
  						 dma_addr_t addr,
  						 unsigned long offset,
  						 size_t size,
  						 enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_single_for_cpu)
  		ops->sync_single_for_cpu(dev, addr + offset, size, dir);
  	debug_dma_sync_single_range_for_cpu(dev, addr, offset, size, dir);
  }
  
  static inline void dma_sync_single_range_for_device(struct device *dev,
  						    dma_addr_t addr,
  						    unsigned long offset,
  						    size_t size,
  						    enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_single_for_device)
  		ops->sync_single_for_device(dev, addr + offset, size, dir);
  	debug_dma_sync_single_range_for_device(dev, addr, offset, size, dir);
  }
  
  static inline void
  dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
  		    int nelems, enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_sg_for_cpu)
  		ops->sync_sg_for_cpu(dev, sg, nelems, dir);
  	debug_dma_sync_sg_for_cpu(dev, sg, nelems, dir);
  }
  
  static inline void
  dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
  		       int nelems, enum dma_data_direction dir)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  
  	BUG_ON(!valid_dma_direction(dir));
  	if (ops->sync_sg_for_device)
  		ops->sync_sg_for_device(dev, sg, nelems, dir);
  	debug_dma_sync_sg_for_device(dev, sg, nelems, dir);
  
  }
  
  #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, NULL)
  #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, NULL)
  #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, NULL)
  #define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, NULL)
  
  extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
  			   void *cpu_addr, dma_addr_t dma_addr, size_t size);
  
  /**
   * dma_mmap_attrs - map a coherent DMA allocation into user space
   * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices
   * @vma: vm_area_struct describing requested user mapping
   * @cpu_addr: kernel CPU-view address returned from dma_alloc_attrs
   * @handle: device-view address returned from dma_alloc_attrs
   * @size: size of memory originally requested in dma_alloc_attrs
   * @attrs: attributes of mapping properties requested in dma_alloc_attrs
   *
   * Map a coherent DMA buffer previously allocated by dma_alloc_attrs
   * into user space.  The coherent DMA buffer must not be freed by the
   * driver until the user space mapping has been released.
   */
  static inline int
  dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, void *cpu_addr,
  	       dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  	BUG_ON(!ops);
  	if (ops->mmap)
  		return ops->mmap(dev, vma, cpu_addr, dma_addr, size, attrs);
  	return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
  }
  
  #define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)
  
  static inline int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
  		      void *cpu_addr, dma_addr_t dma_addr, size_t size)
  {
  	DEFINE_DMA_ATTRS(attrs);
  	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
  	return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size, &attrs);
  }
  
  int
  dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
  		       void *cpu_addr, dma_addr_t dma_addr, size_t size);
  
  static inline int
  dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr,
  		      dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
  {
  	const struct dma_map_ops *ops = get_dma_ops(dev);
  	BUG_ON(!ops);
  	if (ops->get_sgtable)
  		return ops->get_sgtable(dev, sgt, cpu_addr, dma_addr, size,
  					attrs);
  	return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr, size);
  }
  
  #define dma_get_sgtable(d, t, v, h, s) dma_get_sgtable_attrs(d, t, v, h, s, NULL)
  
  #endif
  