text: /*
   * Copyright © 2014 Intel Corporation
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice (including the next
   * paragraph) shall be included in all copies or substantial portions of the
   * Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
   * IN THE SOFTWARE.
   *
   */
  
  #include <linux/mm.h>
  #include <linux/io-mapping.h>
  
  #include <asm/pgtable.h>
  
  #include "i915_drv.h"
  
  struct remap_pfn {
  	struct mm_struct *mm;
  	unsigned long pfn;
  	pgprot_t prot;
  };
  
  #if 0
  static int remap_pfn(pte_t *pte, pgtable_t token,
  		     unsigned long addr, void *data)
  {
  	struct remap_pfn *r = data;
  
  	/* Special PTE are not associated with any struct page */
  	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
  	r->pfn++;
  
  	return 0;
  }
  
  /**
   * remap_io_mapping - remap an IO mapping to userspace
   * @vma: user vma to map to
   * @addr: target user address to start at
   * @pfn: physical address of kernel memory
   * @size: size of map area
   * @iomap: the source io_mapping
   *
   *  Note: this is only safe if the mm semaphore is held when called.
   */
  int remap_io_mapping(struct vm_area_struct *vma,
  		     unsigned long addr, unsigned long pfn, unsigned long size,
  		     struct io_mapping *iomap)
  {
  	struct remap_pfn r;
  	int err;
  
  	GEM_BUG_ON((vma->vm_flags &
  		    (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)) !=
  		   (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP));
  
  	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
  	r.mm = vma->vm_mm;
  	r.pfn = pfn;
  	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
  			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
  
  	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
  	if (unlikely(err)) {
  		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
  		return err;
  	}
  
  	return 0;
  }
  #endif
  