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 <linux/init.h>
  13 #include <linux/slab.h>
  14 #include <asm/io.h>
  15 #include <asm/fixmap.h>
  16 #include <asm/cacheflush.h>
  17 #include <asm/tlbflush.h>
  18 #include <asm/pgtable.h>
  19
  20 #define ISA_START_ADDRESS       0xa0000
  21 #define ISA_END_ADDRESS         0x100000
  22
  23 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  24                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  25 {
  26         pte_t *pte;
  27         unsigned long pfn;
  28
  29         pfn = phys_addr >> PAGE_SHIFT;
  30         pte = pte_alloc_kernel(&init_mm, pmd, addr);
  31         if (!pte)
  32                 return -ENOMEM;
  33         do {
  34                 BUG_ON(!pte_none(*pte));
  35                 set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW |
  36                                         _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
  37                 pfn++;
  38         } while (pte++, addr += PAGE_SIZE, addr != end);
  39         return 0;
  40 }
  41
  42 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  43                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  44 {
  45         pmd_t *pmd;
  46         unsigned long next;
  47
  48         phys_addr -= addr;
  49         pmd = pmd_alloc(&init_mm, pud, addr);
  50         if (!pmd)
  51                 return -ENOMEM;
  52         do {
  53                 next = pmd_addr_end(addr, end);
  54                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, flags))
  55                         return -ENOMEM;
  56         } while (pmd++, addr = next, addr != end);
  57         return 0;
  58 }
  59
  60 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  61                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  62 {
  63         pud_t *pud;
  64         unsigned long next;
  65
  66         phys_addr -= addr;
  67         pud = pud_alloc(&init_mm, pgd, addr);
  68         if (!pud)
  69                 return -ENOMEM;
  70         do {
  71                 next = pud_addr_end(addr, end);
  72                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, flags))
  73                         return -ENOMEM;
  74         } while (pud++, addr = next, addr != end);
  75         return 0;
  76 }
  77
  78 static int ioremap_page_range(unsigned long addr,
  79                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  80 {
  81         pgd_t *pgd;
  82         unsigned long next;
  83         int err;
  84
  85         BUG_ON(addr >= end);
  86         flush_cache_all();
  87         phys_addr -= addr;
  88         pgd = pgd_offset_k(addr);
  89         spin_lock(&init_mm.page_table_lock);
  90         do {
  91                 next = pgd_addr_end(addr, end);
  92                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, flags);
  93                 if (err)
  94                         break;
  95         } while (pgd++, addr = next, addr != end);
  96         spin_unlock(&init_mm.page_table_lock);
  97         flush_tlb_all();
  98         return err;
  99 }
 100
 101 /*
 102  * Generic mapping function (not visible outside):
 103  */
 104
 105 /*
 106  * Remap an arbitrary physical address space into the kernel virtual
 107  * address space. Needed when the kernel wants to access high addresses
 108  * directly.
 109  *
 110  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 111  * have to convert them into an offset in a page-aligned mapping, but the
 112  * caller shouldn't need to know that small detail.
 113  */
 114 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 115 {
 116         void __iomem * addr;
 117         struct vm_struct * area;
 118         unsigned long offset, last_addr;
 119
 120         /* Don't allow wraparound or zero size */
 121         last_addr = phys_addr + size - 1;
 122         if (!size || last_addr < phys_addr)
 123                 return NULL;
 124
 125         /*
 126          * Don't remap the low PCI/ISA area, it's always mapped..
 127          */
 128         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 129                 return (void __iomem *) phys_to_virt(phys_addr);
 130
 131         /*
 132          * Don't allow anybody to remap normal RAM that we're using..
 133          */
 134         if (phys_addr <= virt_to_phys(high_memory - 1)) {
 135                 char *t_addr, *t_end;
 136                 struct page *page;
 137
 138                 t_addr = __va(phys_addr);
 139                 t_end = t_addr + (size - 1);
 140
 141                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 142                         if(!PageReserved(page))
 143                                 return NULL;
 144         }
 145
 146         /*
 147          * Mappings have to be page-aligned
 148          */
 149         offset = phys_addr & ~PAGE_MASK;
 150         phys_addr &= PAGE_MASK;
 151         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 152
 153         /*
 154          * Ok, go for it..
 155          */
 156         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 157         if (!area)
 158                 return NULL;
 159         area->phys_addr = phys_addr;
 160         addr = (void __iomem *) area->addr;
 161         if (ioremap_page_range((unsigned long) addr,
 162                         (unsigned long) addr + size, phys_addr, flags)) {
 163                 vunmap((void __force *) addr);
 164                 return NULL;
 165         }
 166         return (void __iomem *) (offset + (char __iomem *)addr);
 167 }
 168
 169
 170 /**
 171  * ioremap_nocache     -   map bus memory into CPU space
 172  * @offset:    bus address of the memory
 173  * @size:      size of the resource to map
 174  *
 175  * ioremap_nocache performs a platform specific sequence of operations to
 176  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 177  * writew/writel functions and the other mmio helpers. The returned
 178  * address is not guaranteed to be usable directly as a virtual
 179  * address.
 180  *
 181  * This version of ioremap ensures that the memory is marked uncachable
 182  * on the CPU as well as honouring existing caching rules from things like
 183  * the PCI bus. Note that there are other caches and buffers on many
 184  * busses. In particular driver authors should read up on PCI writes
 185  *
 186  * It's useful if some control registers are in such an area and
 187  * write combining or read caching is not desirable:
 188  *
 189  * Must be freed with iounmap.
 190  */
 191
 192 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 193 {
 194         unsigned long last_addr;
 195         void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
 196         if (!p)
 197                 return p;
 198
 199         /* Guaranteed to be > phys_addr, as per __ioremap() */
 200         last_addr = phys_addr + size - 1;
 201
 202         if (last_addr < virt_to_phys(high_memory) - 1) {
 203                 struct page *ppage = virt_to_page(__va(phys_addr));
 204                 unsigned long npages;
 205
 206                 phys_addr &= PAGE_MASK;
 207
 208                 /* This might overflow and become zero.. */
 209                 last_addr = PAGE_ALIGN(last_addr);
 210
 211                 /* .. but that's ok, because modulo-2**n arithmetic will make
 212                 * the page-aligned "last - first" come out right.
 213                 */
 214                 npages = (last_addr - phys_addr) >> PAGE_SHIFT;
 215
 216                 if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
 217                         iounmap(p);
 218                         p = NULL;
 219                 }
 220                 global_flush_tlb();
 221         }
 222
 223         return p;
 224 }
 225
 226 void iounmap(volatile void __iomem *addr)
 227 {
 228         struct vm_struct *p;
 229         if ((void __force *) addr <= high_memory)
 230                 return;
 231
 232         /*
 233          * __ioremap special-cases the PCI/ISA range by not instantiating a
 234          * vm_area and by simply returning an address into the kernel mapping
 235          * of ISA space.   So handle that here.
 236          */
 237         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 238                         addr < phys_to_virt(ISA_END_ADDRESS))
 239                 return;
 240
 241         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 242         if (!p) {
 243                 printk("__iounmap: bad address %p\n", addr);
 244                 return;
 245         }
 246
 247         if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
 248                 /* p->size includes the guard page, but cpa doesn't like that */
 249                 change_page_attr(virt_to_page(__va(p->phys_addr)),
 250                                  p->size >> PAGE_SHIFT,
 251                                  PAGE_KERNEL);
 252                 global_flush_tlb();
 253         }
 254         kfree(p);
 255 }
 256
 257 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 258 {
 259         unsigned long offset, last_addr;
 260         unsigned int nrpages;
 261         enum fixed_addresses idx;
 262
 263         /* Don't allow wraparound or zero size */
 264         last_addr = phys_addr + size - 1;
 265         if (!size || last_addr < phys_addr)
 266                 return NULL;
 267
 268         /*
 269          * Don't remap the low PCI/ISA area, it's always mapped..
 270          */
 271         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 272                 return phys_to_virt(phys_addr);
 273
 274         /*
 275          * Mappings have to be page-aligned
 276          */
 277         offset = phys_addr & ~PAGE_MASK;
 278         phys_addr &= PAGE_MASK;
 279         size = PAGE_ALIGN(last_addr) - phys_addr;
 280
 281         /*
 282          * Mappings have to fit in the FIX_BTMAP area.
 283          */
 284         nrpages = size >> PAGE_SHIFT;
 285         if (nrpages > NR_FIX_BTMAPS)
 286                 return NULL;
 287
 288         /*
 289          * Ok, go for it..
 290          */
 291         idx = FIX_BTMAP_BEGIN;
 292         while (nrpages > 0) {
 293                 set_fixmap(idx, phys_addr);
 294                 phys_addr += PAGE_SIZE;
 295                 --idx;
 296                 --nrpages;
 297         }
 298         return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 299 }
 300
 301 void __init bt_iounmap(void *addr, unsigned long size)
 302 {
 303         unsigned long virt_addr;
 304         unsigned long offset;
 305         unsigned int nrpages;
 306         enum fixed_addresses idx;
 307
 308         virt_addr = (unsigned long)addr;
 309         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 310                 return;
 311         offset = virt_addr & ~PAGE_MASK;
 312         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 313
 314         idx = FIX_BTMAP_BEGIN;
 315         while (nrpages > 0) {
 316                 clear_fixmap(idx);
 317                 --idx;
 318                 --nrpages;
 319         }
 320 }