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 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
  17 static int __read_mostly ioremap_pud_capable;
  18 static int __read_mostly ioremap_pmd_capable;
  19 static int __read_mostly ioremap_huge_disabled;
  20
  21 static int __init set_nohugeiomap(char *str)
  22 {
  23         ioremap_huge_disabled = 1;
  24         return 0;
  25 }
  26 early_param("nohugeiomap", set_nohugeiomap);
  27
  28 void __init ioremap_huge_init(void)
  29 {
  30         if (!ioremap_huge_disabled) {
  31                 if (arch_ioremap_pud_supported())
  32                         ioremap_pud_capable = 1;
  33                 if (arch_ioremap_pmd_supported())
  34                         ioremap_pmd_capable = 1;
  35         }
  36 }
  37
  38 static inline int ioremap_pud_enabled(void)
  39 {
  40         return ioremap_pud_capable;
  41 }
  42
  43 static inline int ioremap_pmd_enabled(void)
  44 {
  45         return ioremap_pmd_capable;
  46 }
  47
  48 #else   /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
  49 static inline int ioremap_pud_enabled(void) { return 0; }
  50 static inline int ioremap_pmd_enabled(void) { return 0; }
  51 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  52
  53 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  54                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  55 {
  56         pte_t *pte;
  57         u64 pfn;
  58
  59         pfn = phys_addr >> PAGE_SHIFT;
  60         pte = pte_alloc_kernel(pmd, addr);
  61         if (!pte)
  62                 return -ENOMEM;
  63         do {
  64                 BUG_ON(!pte_none(*pte));
  65                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  66                 pfn++;
  67         } while (pte++, addr += PAGE_SIZE, addr != end);
  68         return 0;
  69 }
  70
  71 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  72                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  73 {
  74         pmd_t *pmd;
  75         unsigned long next;
  76
  77         phys_addr -= addr;
  78         pmd = pmd_alloc(&init_mm, pud, addr);
  79         if (!pmd)
  80                 return -ENOMEM;
  81         do {
  82                 next = pmd_addr_end(addr, end);
  83
  84                 if (ioremap_pmd_enabled() &&
  85                     ((next - addr) == PMD_SIZE) &&
  86                     IS_ALIGNED(phys_addr + addr, PMD_SIZE) &&
  87                     pmd_free_pte_page(pmd, addr)) {
  88                         if (pmd_set_huge(pmd, phys_addr + addr, prot))
  89                                 continue;
  90                 }
  91
  92                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
  93                         return -ENOMEM;
  94         } while (pmd++, addr = next, addr != end);
  95         return 0;
  96 }
  97
  98 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  99                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 100 {
 101         pud_t *pud;
 102         unsigned long next;
 103
 104         phys_addr -= addr;
 105         pud = pud_alloc(&init_mm, pgd, addr);
 106         if (!pud)
 107                 return -ENOMEM;
 108         do {
 109                 next = pud_addr_end(addr, end);
 110
 111                 if (ioremap_pud_enabled() &&
 112                     ((next - addr) == PUD_SIZE) &&
 113                     IS_ALIGNED(phys_addr + addr, PUD_SIZE) &&
 114                     pud_free_pmd_page(pud, addr)) {
 115                         if (pud_set_huge(pud, phys_addr + addr, prot))
 116                                 continue;
 117                 }
 118
 119                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
 120                         return -ENOMEM;
 121         } while (pud++, addr = next, addr != end);
 122         return 0;
 123 }
 124
 125 int ioremap_page_range(unsigned long addr,
 126                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 127 {
 128         pgd_t *pgd;
 129         unsigned long start;
 130         unsigned long next;
 131         int err;
 132
 133         BUG_ON(addr >= end);
 134
 135         start = addr;
 136         phys_addr -= addr;
 137         pgd = pgd_offset_k(addr);
 138         do {
 139                 next = pgd_addr_end(addr, end);
 140                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, prot);
 141                 if (err)
 142                         break;
 143         } while (pgd++, addr = next, addr != end);
 144
 145         flush_cache_vmap(start, end);
 146
 147         return err;
 148 }
 149 EXPORT_SYMBOL_GPL(ioremap_page_range);