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(&init_mm, 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         spin_lock(&init_mm.page_table_lock);
  91         do {
  92                 next = pgd_addr_end(addr, end);
  93                 err = ioremap_pud_range(pgd, addr, next, phys_addr+addr, flags);
  94                 if (err)
  95                         break;
  96         } while (pgd++, addr = next, addr != end);
  97         spin_unlock(&init_mm.page_table_lock);
  98         flush_tlb_all();
  99         return err;
 100 }
 101
 102 /*
 103  * Generic mapping function (not visible outside):
 104  */
 105
 106 /*
 107  * Remap an arbitrary physical address space into the kernel virtual
 108  * address space. Needed when the kernel wants to access high addresses
 109  * directly.
 110  *
 111  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 112  * have to convert them into an offset in a page-aligned mapping, but the
 113  * caller shouldn't need to know that small detail.
 114  */
 115 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 116 {
 117         void __iomem * addr;
 118         struct vm_struct * area;
 119         unsigned long offset, last_addr;
 120
 121         /* Don't allow wraparound or zero size */
 122         last_addr = phys_addr + size - 1;
 123         if (!size || last_addr < phys_addr)
 124                 return NULL;
 125
 126         /*
 127          * Don't remap the low PCI/ISA area, it's always mapped..
 128          */
 129         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 130                 return (void __iomem *) phys_to_virt(phys_addr);
 131
 132         /*
 133          * Don't allow anybody to remap normal RAM that we're using..
 134          */
 135         if (phys_addr <= virt_to_phys(high_memory - 1)) {
 136                 char *t_addr, *t_end;
 137                 struct page *page;
 138
 139                 t_addr = __va(phys_addr);
 140                 t_end = t_addr + (size - 1);
 141
 142                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 143                         if(!PageReserved(page))
 144                                 return NULL;
 145         }
 146
 147         /*
 148          * Mappings have to be page-aligned
 149          */
 150         offset = phys_addr & ~PAGE_MASK;
 151         phys_addr &= PAGE_MASK;
 152         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 153
 154         /*
 155          * Ok, go for it..
 156          */
 157         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 158         if (!area)
 159                 return NULL;
 160         area->phys_addr = phys_addr;
 161         addr = (void __iomem *) area->addr;
 162         if (ioremap_page_range((unsigned long) addr,
 163                         (unsigned long) addr + size, phys_addr, flags)) {
 164                 vunmap((void __force *) addr);
 165                 return NULL;
 166         }
 167         return (void __iomem *) (offset + (char __iomem *)addr);
 168 }
 169 EXPORT_SYMBOL(__ioremap);
 170
 171 /**
 172  * ioremap_nocache     -   map bus memory into CPU space
 173  * @offset:    bus address of the memory
 174  * @size:      size of the resource to map
 175  *
 176  * ioremap_nocache performs a platform specific sequence of operations to
 177  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 178  * writew/writel functions and the other mmio helpers. The returned
 179  * address is not guaranteed to be usable directly as a virtual
 180  * address.
 181  *
 182  * This version of ioremap ensures that the memory is marked uncachable
 183  * on the CPU as well as honouring existing caching rules from things like
 184  * the PCI bus. Note that there are other caches and buffers on many
 185  * busses. In particular driver authors should read up on PCI writes
 186  *
 187  * It's useful if some control registers are in such an area and
 188  * write combining or read caching is not desirable:
 189  *
 190  * Must be freed with iounmap.
 191  */
 192
 193 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 194 {
 195         unsigned long last_addr;
 196         void __iomem *p = __ioremap(phys_addr, size, _PAGE_PCD);
 197         if (!p)
 198                 return p;
 199
 200         /* Guaranteed to be > phys_addr, as per __ioremap() */
 201         last_addr = phys_addr + size - 1;
 202
 203         if (last_addr < virt_to_phys(high_memory) - 1) {
 204                 struct page *ppage = virt_to_page(__va(phys_addr));
 205                 unsigned long npages;
 206
 207                 phys_addr &= PAGE_MASK;
 208
 209                 /* This might overflow and become zero.. */
 210                 last_addr = PAGE_ALIGN(last_addr);
 211
 212                 /* .. but that's ok, because modulo-2**n arithmetic will make
 213                 * the page-aligned "last - first" come out right.
 214                 */
 215                 npages = (last_addr - phys_addr) >> PAGE_SHIFT;
 216
 217                 if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
 218                         iounmap(p);
 219                         p = NULL;
 220                 }
 221                 global_flush_tlb();
 222         }
 223
 224         return p;
 225 }
 226 EXPORT_SYMBOL(ioremap_nocache);
 227
 228 void iounmap(volatile void __iomem *addr)
 229 {
 230         struct vm_struct *p;
 231
 232         if ((void __force *)addr <= high_memory)
 233                 return;
 234
 235         /*
 236          * __ioremap special-cases the PCI/ISA range by not instantiating a
 237          * vm_area and by simply returning an address into the kernel mapping
 238          * of ISA space.   So handle that here.
 239          */
 240         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 241                         addr < phys_to_virt(ISA_END_ADDRESS))
 242                 return;
 243
 244         write_lock(&vmlist_lock);
 245         p = __remove_vm_area((void *)(PAGE_MASK & (unsigned long __force)addr));
 246         if (!p) {
 247                 printk(KERN_WARNING "iounmap: bad address %p\n", addr);
 248                 dump_stack();
 249                 goto out_unlock;
 250         }
 251
 252         if ((p->flags >> 20) && p->phys_addr < virt_to_phys(high_memory) - 1) {
 253                 change_page_attr(virt_to_page(__va(p->phys_addr)),
 254                                  p->size >> PAGE_SHIFT,
 255                                  PAGE_KERNEL);
 256                 global_flush_tlb();
 257         }
 258 out_unlock:
 259         write_unlock(&vmlist_lock);
 260         kfree(p);
 261 }
 262 EXPORT_SYMBOL(iounmap);
 263
 264 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
 265 {
 266         unsigned long offset, last_addr;
 267         unsigned int nrpages;
 268         enum fixed_addresses idx;
 269
 270         /* Don't allow wraparound or zero size */
 271         last_addr = phys_addr + size - 1;
 272         if (!size || last_addr < phys_addr)
 273                 return NULL;
 274
 275         /*
 276          * Don't remap the low PCI/ISA area, it's always mapped..
 277          */
 278         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 279                 return phys_to_virt(phys_addr);
 280
 281         /*
 282          * Mappings have to be page-aligned
 283          */
 284         offset = phys_addr & ~PAGE_MASK;
 285         phys_addr &= PAGE_MASK;
 286         size = PAGE_ALIGN(last_addr) - phys_addr;
 287
 288         /*
 289          * Mappings have to fit in the FIX_BTMAP area.
 290          */
 291         nrpages = size >> PAGE_SHIFT;
 292         if (nrpages > NR_FIX_BTMAPS)
 293                 return NULL;
 294
 295         /*
 296          * Ok, go for it..
 297          */
 298         idx = FIX_BTMAP_BEGIN;
 299         while (nrpages > 0) {
 300                 set_fixmap(idx, phys_addr);
 301                 phys_addr += PAGE_SIZE;
 302                 --idx;
 303                 --nrpages;
 304         }
 305         return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
 306 }
 307
 308 void __init bt_iounmap(void *addr, unsigned long size)
 309 {
 310         unsigned long virt_addr;
 311         unsigned long offset;
 312         unsigned int nrpages;
 313         enum fixed_addresses idx;
 314
 315         virt_addr = (unsigned long)addr;
 316         if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
 317                 return;
 318         offset = virt_addr & ~PAGE_MASK;
 319         nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
 320
 321         idx = FIX_BTMAP_BEGIN;
 322         while (nrpages > 0) {
 323                 clear_fixmap(idx);
 324                 --idx;
 325                 --nrpages;
 326         }
 327 }