lib/ioremap.c

   1 /*
   2  * Re-map IO memory to kernel address space so that we can access it.
   3  * This is needed for high PCI addresses that aren't mapped in the
   4  * 640k-1MB IO memory area on PC's
   5  *
   6  * (C) Copyright 1995 1996 Linus Torvalds
   7  */
   8 #include <linux/vmalloc.h>
   9 #include <linux/mm.h>
  10 #include <linux/sched.h>
  11 #include <linux/io.h>
  12 #include <asm/cacheflush.h>
  13 #include <asm/pgtable.h>
  14
  15 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  16                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  17 {
  18         pte_t *pte;
  19         unsigned long pfn;
  20
  21         pfn = phys_addr >> PAGE_SHIFT;
  22         pte = pte_alloc_kernel(pmd, addr);
  23         if (!pte)
  24                 return -ENOMEM;
  25         do {
  26                 BUG_ON(!pte_none(*pte));
  27                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  28                 pfn++;
  29         } while (pte++, addr += PAGE_SIZE, addr != end);
  30         return 0;
  31 }
  32
  33 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  34                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  35 {
  36         pmd_t *pmd;
  37         unsigned long next;
  38
  39         phys_addr -= addr;
  40         pmd = pmd_alloc(&init_mm, pud, addr);
  41         if (!pmd)
  42                 return -ENOMEM;
  43         do {
  44                 next = pmd_addr_end(addr, end);
  45                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
  46                         return -ENOMEM;
  47         } while (pmd++, addr = next, addr != end);
  48         return 0;
  49 }
  50
  51 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  52                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  53 {
  54         pud_t *pud;
  55         unsigned long next;
  56
  57         phys_addr -= addr;
  58         pud = pud_alloc(&init_mm, pgd, addr);
  59         if (!pud)
  60                 return -ENOMEM;
  61         do {
  62                 next = pud_addr_end(addr, end);
  63                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
  64                         return -ENOMEM;
  65         } while (pud++, addr = next, addr != end);
  66         return 0;
  67 }
  68
  69 int ioremap_page_range(unsigned long addr,
  70                        unsigned long end, unsigned long phys_addr, pgprot_t prot)
  71 {
  72         pgd_t *pgd;
  73         unsigned long start;
  74         unsigned long next;
  75         int err;
  76
  77         BUG_ON(addr >= end);
  78
  79         start = addr;
  80         phys_addr -= addr;
  81         pgd = pgd_offset_k(addr);
  82         do {
  83                 next = pgd_addr_end(addr, end);
  84                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
  85                 if (err)
  86                         break;
  87         } while (pgd++, addr = next, addr != end);
  88
  89         flush_cache_vmap(start, end);
  90
  91         return err;
  92 }