/*
   * Re-map IO memory to kernel address space so that we can access it.
   * This is needed for high PCI addresses that aren't mapped in the
   * 640k-1MB IO memory area on PC's
   *
   * (C) Copyright 1995 1996 Linus Torvalds
   */

  #include <linux/vmalloc.h>
  #include <linux/mm.h>
  
  #include <asm/cacheflush.h>
  #include <asm/pgtable.h>
  
  static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  		unsigned long end, unsigned long phys_addr, pgprot_t prot)
  {
  	pte_t *pte;
  	unsigned long pfn;
  
  	pfn = phys_addr >> PAGE_SHIFT;
  	pte = pte_alloc_kernel(pmd, addr);
  	if (!pte)
  		return -ENOMEM;
  	do {
  		BUG_ON(!pte_none(*pte));
  		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  		pfn++;
  	} while (pte++, addr += PAGE_SIZE, addr != end);
  	return 0;
  }
  
  static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  		unsigned long end, unsigned long phys_addr, pgprot_t prot)
  {
  	pmd_t *pmd;
  	unsigned long next;
  
  	phys_addr -= addr;
  	pmd = pmd_alloc(&init_mm, pud, addr);
  	if (!pmd)
  		return -ENOMEM;
  	do {
  		next = pmd_addr_end(addr, end);
  		if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
  			return -ENOMEM;
  	} while (pmd++, addr = next, addr != end);
  	return 0;
  }
  
  static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  		unsigned long end, unsigned long phys_addr, pgprot_t prot)
  {
  	pud_t *pud;
  	unsigned long next;
  
  	phys_addr -= addr;
  	pud = pud_alloc(&init_mm, pgd, addr);
  	if (!pud)
  		return -ENOMEM;
  	do {
  		next = pud_addr_end(addr, end);
  		if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
  			return -ENOMEM;
  	} while (pud++, addr = next, addr != end);
  	return 0;
  }
  
  int ioremap_page_range(unsigned long addr,
  		       unsigned long end, unsigned long phys_addr, pgprot_t prot)
  {
  	pgd_t *pgd;
  	unsigned long start;
  	unsigned long next;
  	int err;
  
  	BUG_ON(addr >= end);

  	start = addr;
  	phys_addr -= addr;
  	pgd = pgd_offset_k(addr);
  	do {
  		next = pgd_addr_end(addr, end);
  		err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
  		if (err)
  			break;
  	} while (pgd++, addr = next, addr != end);

  	flush_cache_vmap(start, end);

  
  	return err;
  }