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 <asm/cacheflush.h>
  12 #include <asm/pgtable.h>
  13
  14 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  15                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  16 {
  17         pte_t *pte;
  18         unsigned long pfn;
  19
  20         pfn = phys_addr >> PAGE_SHIFT;
  21         pte = pte_alloc_kernel(pmd, addr);
  22         if (!pte)
  23                 return -ENOMEM;
  24         do {
  25                 BUG_ON(!pte_none(*pte));
  26                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  27                 pfn++;
  28         } while (pte++, addr += PAGE_SIZE, addr != end);
  29         return 0;
  30 }
  31
  32 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  33                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  34 {
  35         pmd_t *pmd;
  36         unsigned long next;
  37
  38         phys_addr -= addr;
  39         pmd = pmd_alloc(&init_mm, pud, addr);
  40         if (!pmd)
  41                 return -ENOMEM;
  42         do {
  43                 next = pmd_addr_end(addr, end);
  44                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
  45                         return -ENOMEM;
  46         } while (pmd++, addr = next, addr != end);
  47         return 0;
  48 }
  49
  50 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  51                 unsigned long end, unsigned long phys_addr, pgprot_t prot)
  52 {
  53         pud_t *pud;
  54         unsigned long next;
  55
  56         phys_addr -= addr;
  57         pud = pud_alloc(&init_mm, pgd, addr);
  58         if (!pud)
  59                 return -ENOMEM;
  60         do {
  61                 next = pud_addr_end(addr, end);
  62                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
  63                         return -ENOMEM;
  64         } while (pud++, addr = next, addr != end);
  65         return 0;
  66 }
  67
  68 int ioremap_page_range(unsigned long addr,
  69                        unsigned long end, unsigned long phys_addr, pgprot_t prot)
  70 {
  71         pgd_t *pgd;
  72         unsigned long start;
  73         unsigned long next;
  74         int err;
  75
  76         BUG_ON(addr >= end);
  77
  78         start = addr;
  79         phys_addr -= addr;
  80         pgd = pgd_offset_k(addr);
  81         do {
  82                 next = pgd_addr_end(addr, end);
  83                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
  84                 if (err)
  85                         break;
  86         } while (pgd++, addr = next, addr != end);
  87
  88         flush_cache_vmap(start, end);
  89
  90         return err;
  91 }