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 <linux/export.h>
  13 #include <asm/cacheflush.h>
  14 #include <asm/pgtable.h>
  15
  16 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  17                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  18 {
  19         pte_t *pte;
  20         u64 pfn;
  21
  22         pfn = phys_addr >> PAGE_SHIFT;
  23         pte = pte_alloc_kernel(pmd, addr);
  24         if (!pte)
  25                 return -ENOMEM;
  26         do {
  27                 BUG_ON(!pte_none(*pte));
  28                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  29                 pfn++;
  30         } while (pte++, addr += PAGE_SIZE, addr != end);
  31         return 0;
  32 }
  33
  34 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  35                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  36 {
  37         pmd_t *pmd;
  38         unsigned long next;
  39
  40         phys_addr -= addr;
  41         pmd = pmd_alloc(&init_mm, pud, addr);
  42         if (!pmd)
  43                 return -ENOMEM;
  44         do {
  45                 next = pmd_addr_end(addr, end);
  46                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
  47                         return -ENOMEM;
  48         } while (pmd++, addr = next, addr != end);
  49         return 0;
  50 }
  51
  52 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  53                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  54 {
  55         pud_t *pud;
  56         unsigned long next;
  57
  58         phys_addr -= addr;
  59         pud = pud_alloc(&init_mm, pgd, addr);
  60         if (!pud)
  61                 return -ENOMEM;
  62         do {
  63                 next = pud_addr_end(addr, end);
  64                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
  65                         return -ENOMEM;
  66         } while (pud++, addr = next, addr != end);
  67         return 0;
  68 }
  69
  70 int ioremap_page_range(unsigned long addr,
  71                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  72 {
  73         pgd_t *pgd;
  74         unsigned long start;
  75         unsigned long next;
  76         int err;
  77
  78         BUG_ON(addr >= end);
  79
  80         start = addr;
  81         phys_addr -= addr;
  82         pgd = pgd_offset_k(addr);
  83         do {
  84                 next = pgd_addr_end(addr, end);
  85                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
  86                 if (err)
  87                         break;
  88         } while (pgd++, addr = next, addr != end);
  89
  90         flush_cache_vmap(start, end);
  91
  92         return err;
  93 }
  94 EXPORT_SYMBOL_GPL(ioremap_page_range);