arch/i386/mm/ioremap.c

   1 /*
   2  * arch/i386/mm/ioremap.c
   3  *
   4  * Re-map IO memory to kernel address space so that we can access it.
   5  * This is needed for high PCI addresses that aren't mapped in the
   6  * 640k-1MB IO memory area on PC's
   7  *
   8  * (C) Copyright 1995 1996 Linus Torvalds
   9  */
  10
  11 #include <linux/vmalloc.h>
  12 #include <asm/io.h>
  13 #include <asm/pgalloc.h>
  14
  15 static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  16         unsigned long phys_addr, unsigned long flags)
  17 {
  18         unsigned long end;
  19
  20         address &= ~PMD_MASK;
  21         end = address + size;
  22         if (end > PMD_SIZE)
  23                 end = PMD_SIZE;
  24         if (address >= end)
  25                 BUG();
  26         do {
  27                 if (!pte_none(*pte)) {
  28                         printk("remap_area_pte: page already exists\n");
  29                         BUG();
  30                 }
  31                 set_pte(pte, mk_pte_phys(phys_addr, __pgprot(_PAGE_PRESENT | _PAGE_RW |
  32                                         _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
  33                 address += PAGE_SIZE;
  34                 phys_addr += PAGE_SIZE;
  35                 pte++;
  36         } while (address && (address < end));
  37 }
  38
  39 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  40         unsigned long phys_addr, unsigned long flags)
  41 {
  42         unsigned long end;
  43
  44         address &= ~PGDIR_MASK;
  45         end = address + size;
  46         if (end > PGDIR_SIZE)
  47                 end = PGDIR_SIZE;
  48         phys_addr -= address;
  49         if (address >= end)
  50                 BUG();
  51         do {
  52                 pte_t * pte = pte_alloc(&init_mm, pmd, address);
  53                 if (!pte)
  54                         return -ENOMEM;
  55                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  56                 address = (address + PMD_SIZE) & PMD_MASK;
  57                 pmd++;
  58         } while (address && (address < end));
  59         return 0;
  60 }
  61
  62 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  63                                  unsigned long size, unsigned long flags)
  64 {
  65         int error;
  66         pgd_t * dir;
  67         unsigned long end = address + size;
  68
  69         phys_addr -= address;
  70         dir = pgd_offset(&init_mm, address);
  71         flush_cache_all();
  72         if (address >= end)
  73                 BUG();
  74         spin_lock(&init_mm.page_table_lock);
  75         do {
  76                 pmd_t *pmd;
  77                 pmd = pmd_alloc(&init_mm, dir, address);
  78                 error = -ENOMEM;
  79                 if (!pmd)
  80                         break;
  81                 if (remap_area_pmd(pmd, address, end - address,
  82                                          phys_addr + address, flags))
  83                         break;
  84                 error = 0;
  85                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
  86                 dir++;
  87         } while (address && (address < end));
  88         spin_unlock(&init_mm.page_table_lock);
  89         flush_tlb_all();
  90         return error;
  91 }
  92
  93 /*
  94  * Generic mapping function (not visible outside):
  95  */
  96
  97 /*
  98  * Remap an arbitrary physical address space into the kernel virtual
  99  * address space. Needed when the kernel wants to access high addresses
 100  * directly.
 101  *
 102  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 103  * have to convert them into an offset in a page-aligned mapping, but the
 104  * caller shouldn't need to know that small detail.
 105  */
 106 void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 107 {
 108         void * addr;
 109         struct vm_struct * area;
 110         unsigned long offset, last_addr;
 111
 112         /* Don't allow wraparound or zero size */
 113         last_addr = phys_addr + size - 1;
 114         if (!size || last_addr < phys_addr)
 115                 return NULL;
 116
 117         /*
 118          * Don't remap the low PCI/ISA area, it's always mapped..
 119          */
 120         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 121                 return phys_to_virt(phys_addr);
 122
 123         /*
 124          * Don't allow anybody to remap normal RAM that we're using..
 125          */
 126         if (phys_addr < virt_to_phys(high_memory)) {
 127                 char *t_addr, *t_end;
 128                 struct page *page;
 129
 130                 t_addr = __va(phys_addr);
 131                 t_end = t_addr + (size - 1);
 132
 133                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 134                         if(!PageReserved(page))
 135                                 return NULL;
 136         }
 137
 138         /*
 139          * Mappings have to be page-aligned
 140          */
 141         offset = phys_addr & ~PAGE_MASK;
 142         phys_addr &= PAGE_MASK;
 143         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 144
 145         /*
 146          * Ok, go for it..
 147          */
 148         area = get_vm_area(size, VM_IOREMAP);
 149         if (!area)
 150                 return NULL;
 151         addr = area->addr;
 152         if (remap_area_pages(VMALLOC_VMADDR(addr), phys_addr, size, flags)) {
 153                 vfree(addr);
 154                 return NULL;
 155         }
 156         return (void *) (offset + (char *)addr);
 157 }
 158
 159 void iounmap(void *addr)
 160 {
 161         if (addr > high_memory)
 162                 return vfree((void *) (PAGE_MASK & (unsigned long) addr));
 163 }
 164
 165 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 166 {
 167         unsigned long offset, last_addr;
 168         unsigned int nrpages;
 169         enum fixed_addresses idx;
 170
 171         /* Don't allow wraparound or zero size */
 172         last_addr = phys_addr + size - 1;
 173         if (!size || last_addr < phys_addr)
 174                 return NULL;
 175
 176         /*
 177          * Don't remap the low PCI/ISA area, it's always mapped..
 178          */
 179         if (phys_addr >= 0xA0000 && last_addr < 0x100000)
 180                 return phys_to_virt(phys_addr);
 181
 182         /*
 183          * Mappings have to be page-aligned
 184          */
 185         offset = phys_addr & ~PAGE_MASK;
 186         phys_addr &= PAGE_MASK;
 187         size = PAGE_ALIGN(last_addr) - phys_addr;
 188
 189         /*
 190          * Mappings have to fit in the FIX_BTMAP area.
 191          */
 192         nrpages = size >> PAGE_SHIFT;
 193         if (nrpages > NR_FIX_BTMAPS)
 194                 return NULL;
 195
 196         /*
 197          * Ok, go for it..
 198          */
 199         idx = FIX_BTMAP_BEGIN;
 200         while (nrpages > 0) {
 201                 set_fixmap(idx, phys_addr);
 202                 phys_addr += PAGE_SIZE;
 203                 --idx;
 204                 --nrpages;
 205         }
 206         return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 207 }
 208
 209 void __init bt_iounmap(void *addr, unsigned long size)
 210 {
 211         unsigned long virt_addr;
 212         unsigned long offset;
 213         unsigned int nrpages;
 214         enum fixed_addresses idx;
 215
 216         virt_addr = (unsigned long)addr;
 217         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 218                 return;
 219         offset = virt_addr & ~PAGE_MASK;
 220         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 221
 222         idx = FIX_BTMAP_BEGIN;
 223         while (nrpages > 0) {
 224                 __set_fixmap(idx, 0, __pgprot(0));
 225                 --idx;
 226                 --nrpages;
 227         }
 228 }