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 <linux/module.h>
  15 #include <asm/io.h>
  16 #include <asm/fixmap.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/pgtable.h>
  20
  21 #define ISA_START_ADDRESS       0xa0000
  22 #define ISA_END_ADDRESS         0x100000
  23
  24 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  25                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  26 {
  27         pte_t *pte;
  28         unsigned long pfn;
  29
  30         pfn = phys_addr >> PAGE_SHIFT;
  31         pte = pte_alloc_kernel(pmd, addr);
  32         if (!pte)
  33                 return -ENOMEM;
  34         do {
  35                 BUG_ON(!pte_none(*pte));
  36                 set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW |
  37                                         _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
  38                 pfn++;
  39         } while (pte++, addr += PAGE_SIZE, addr != end);
  40         return 0;
  41 }
  42
  43 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  44                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  45 {
  46         pmd_t *pmd;
  47         unsigned long next;
  48
  49         phys_addr -= addr;
  50         pmd = pmd_alloc(&init_mm, pud, addr);
  51         if (!pmd)
  52                 return -ENOMEM;
  53         do {
  54                 next = pmd_addr_end(addr, end);
  55                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, flags))
  56                         return -ENOMEM;
  57         } while (pmd++, addr = next, addr != end);
  58         return 0;
  59 }
  60
  61 static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
  62                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  63 {
  64         pud_t *pud;
  65         unsigned long next;
  66
  67         phys_addr -= addr;
  68         pud = pud_alloc(&init_mm, pgd, addr);
  69         if (!pud)
  70                 return -ENOMEM;
  71         do {
  72                 next = pud_addr_end(addr, end);
  73                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, flags))
  74                         return -ENOMEM;
  75         } while (pud++, addr = next, addr != end);
  76         return 0;
  77 }
  78
  79 static int ioremap_page_range(unsigned long addr,
  80                 unsigned long end, unsigned long phys_addr, unsigned long flags)
  81 {
  82         pgd_t *pgd;
  83         unsigned long next;
  84         int err;
  85
  86         BUG_ON(addr >= end);
  87         flush_cache_all();
  88         phys_addr -= addr;
  89         pgd = pgd_offset_k(addr);
  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         flush_tlb_all();
  97         return err;
  98 }
  99
 100 /*
 101  * Generic mapping function (not visible outside):
 102  */
 103
 104 /*
 105  * Remap an arbitrary physical address space into the kernel virtual
 106  * address space. Needed when the kernel wants to access high addresses
 107  * directly.
 108  *
 109  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 110  * have to convert them into an offset in a page-aligned mapping, but the
 111  * caller shouldn't need to know that small detail.
 112  */
 113 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 114 {
 115         void __iomem * addr;
 116         struct vm_struct * area;
 117         unsigned long offset, last_addr;
 118
 119         /* Don't allow wraparound or zero size */
 120         last_addr = phys_addr + size - 1;
 121         if (!size || last_addr < phys_addr)
 122                 return NULL;
 123
 124         /*
 125          * Don't remap the low PCI/ISA area, it's always mapped..
 126          */
 127         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 128                 return (void __iomem *) phys_to_virt(phys_addr);
 129
 130         /*
 131          * Don't allow anybody to remap normal RAM that we're using..
 132          */
 133         if (phys_addr <= virt_to_phys(high_memory - 1)) {
 134                 char *t_addr, *t_end;
 135                 struct page *page;
 136
 137                 t_addr = __va(phys_addr);
 138                 t_end = t_addr + (size - 1);
 139
 140                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 141                         if(!PageReserved(page))
 142                                 return NULL;
 143         }
 144
 145         /*
 146          * Mappings have to be page-aligned
 147          */
 148         offset = phys_addr & ~PAGE_MASK;
 149         phys_addr &= PAGE_MASK;
 150         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 151
 152         /*
 153          * Ok, go for it..
 154          */
 155         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 156         if (!area)
 157                 return NULL;
 158         area->phys_addr = phys_addr;
 159         addr = (void __iomem *) area->addr;
 160         if (ioremap_page_range((unsigned long) addr,
 161                         (unsigned long) addr + size, phys_addr, flags)) {
 162                 vunmap((void __force *) addr);
 163                 return NULL;
 164         }
 165         return (void __iomem *) (offset + (char __iomem *)addr);
 166 }
 167 EXPORT_SYMBOL(__ioremap);
 168
 169 /**
 170  * ioremap_nocache     -   map bus memory into CPU space
 171  * @offset:    bus address of the memory
 172  * @size:      size of the resource to map
 173  *
 174  * ioremap_nocache performs a platform specific sequence of operations to
 175  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 176  * writew/writel functions and the other mmio helpers. The returned
 177  * address is not guaranteed to be usable directly as a virtual
 178  * address.
 179  *
 180  * This version of ioremap ensures that the memory is marked uncachable
 181  * on the CPU as well as honouring existing caching rules from things like
 182  * the PCI bus. Note that there are other caches and buffers on many
 183  * busses. In particular driver authors should read up on PCI writes
 184  *
 185  * It's useful if some control registers are in such an area and
 186  * write combining or read caching is not desirable:
 187  *
 188  * Must be freed with iounmap.
 189  */
 190
 191 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 192 {
 193         unsigned long last_addr;
 194         void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
 195         if (!p)
 196                 return p;
 197
 198         /* Guaranteed to be > phys_addr, as per __ioremap() */
 199         last_addr = phys_addr + size - 1;
 200
 201         if (last_addr < virt_to_phys(high_memory) - 1) {
 202                 struct page *ppage = virt_to_page(__va(phys_addr));
 203                 unsigned long npages;
 204
 205                 phys_addr &= PAGE_MASK;
 206
 207                 /* This might overflow and become zero.. */
 208                 last_addr = PAGE_ALIGN(last_addr);
 209
 210                 /* .. but that's ok, because modulo-2**n arithmetic will make
 211                 * the page-aligned "last - first" come out right.
 212                 */
 213                 npages = (last_addr - phys_addr) >> PAGE_SHIFT;
 214
 215                 if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
 216                         iounmap(p);
 217                         p = NULL;
 218                 }
 219                 global_flush_tlb();
 220         }
 221
 222         return p;
 223 }
 224 EXPORT_SYMBOL(ioremap_nocache);
 225
 226 /**
 227  * iounmap - Free a IO remapping
 228  * @addr: virtual address from ioremap_*
 229  *
 230  * Caller must ensure there is only one unmapping for the same pointer.
 231  */
 232 void iounmap(volatile void __iomem *addr)
 233 {
 234         struct vm_struct *p, *o;
 235
 236         if ((void __force *)addr <= high_memory)
 237                 return;
 238
 239         /*
 240          * __ioremap special-cases the PCI/ISA range by not instantiating a
 241          * vm_area and by simply returning an address into the kernel mapping
 242          * of ISA space.   So handle that here.
 243          */
 244         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 245                         addr < phys_to_virt(ISA_END_ADDRESS))
 246                 return;
 247
 248         addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long __force)addr);
 249
 250         /* Use the vm area unlocked, assuming the caller
 251            ensures there isn't another iounmap for the same address
 252            in parallel. Reuse of the virtual address is prevented by
 253            leaving it in the global lists until we're done with it.
 254            cpa takes care of the direct mappings. */
 255         read_lock(&vmlist_lock);
 256         for (p = vmlist; p; p = p->next) {
 257                 if (p->addr == addr)
 258                         break;
 259         }
 260         read_unlock(&vmlist_lock);
 261
 262         if (!p) {
 263                 printk("iounmap: bad address %p\n", addr);
 264                 dump_stack();
 265                 return;
 266         }
 267
 268         /* Reset the direct mapping. Can block */
 269         if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
 270                 change_page_attr(virt_to_page(__va(p->phys_addr)),
 271                                  p->size >> PAGE_SHIFT,
 272                                  PAGE_KERNEL);
 273                 global_flush_tlb();
 274         }
 275
 276         /* Finally remove it */
 277         o = remove_vm_area((void *)addr);
 278         BUG_ON(p != o || o == NULL);
 279         kfree(p);
 280 }
 281 EXPORT_SYMBOL(iounmap);
 282
 283 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 284 {
 285         unsigned long offset, last_addr;
 286         unsigned int nrpages;
 287         enum fixed_addresses idx;
 288
 289         /* Don't allow wraparound or zero size */
 290         last_addr = phys_addr + size - 1;
 291         if (!size || last_addr < phys_addr)
 292                 return NULL;
 293
 294         /*
 295          * Don't remap the low PCI/ISA area, it's always mapped..
 296          */
 297         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 298                 return phys_to_virt(phys_addr);
 299
 300         /*
 301          * Mappings have to be page-aligned
 302          */
 303         offset = phys_addr & ~PAGE_MASK;
 304         phys_addr &= PAGE_MASK;
 305         size = PAGE_ALIGN(last_addr) - phys_addr;
 306
 307         /*
 308          * Mappings have to fit in the FIX_BTMAP area.
 309          */
 310         nrpages = size >> PAGE_SHIFT;
 311         if (nrpages > NR_FIX_BTMAPS)
 312                 return NULL;
 313
 314         /*
 315          * Ok, go for it..
 316          */
 317         idx = FIX_BTMAP_BEGIN;
 318         while (nrpages > 0) {
 319                 set_fixmap(idx, phys_addr);
 320                 phys_addr += PAGE_SIZE;
 321                 --idx;
 322                 --nrpages;
 323         }
 324         return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 325 }
 326
 327 void __init bt_iounmap(void *addr, unsigned long size)
 328 {
 329         unsigned long virt_addr;
 330         unsigned long offset;
 331         unsigned int nrpages;
 332         enum fixed_addresses idx;
 333
 334         virt_addr = (unsigned long)addr;
 335         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 336                 return;
 337         offset = virt_addr & ~PAGE_MASK;
 338         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 339
 340         idx = FIX_BTMAP_BEGIN;
 341         while (nrpages > 0) {
 342                 clear_fixmap(idx);
 343                 --idx;
 344                 --nrpages;
 345         }
 346 }