arch/x86_64/mm/ioremap.c

   1 /*
   2  * arch/x86_64/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/pgalloc.h>
  16 #include <asm/fixmap.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/proto.h>
  20
  21 #define ISA_START_ADDRESS      0xa0000
  22 #define ISA_END_ADDRESS                0x100000
  23
  24 static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
  25         unsigned long phys_addr, unsigned long flags)
  26 {
  27         unsigned long end;
  28         unsigned long pfn;
  29
  30         address &= ~PMD_MASK;
  31         end = address + size;
  32         if (end > PMD_SIZE)
  33                 end = PMD_SIZE;
  34         if (address >= end)
  35                 BUG();
  36         pfn = phys_addr >> PAGE_SHIFT;
  37         do {
  38                 if (!pte_none(*pte)) {
  39                         printk("remap_area_pte: page already exists\n");
  40                         BUG();
  41                 }
  42                 set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW |
  43                                         _PAGE_GLOBAL | _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
  44                 address += PAGE_SIZE;
  45                 pfn++;
  46                 pte++;
  47         } while (address && (address < end));
  48 }
  49
  50 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
  51         unsigned long phys_addr, unsigned long flags)
  52 {
  53         unsigned long end;
  54
  55         address &= ~PUD_MASK;
  56         end = address + size;
  57         if (end > PUD_SIZE)
  58                 end = PUD_SIZE;
  59         phys_addr -= address;
  60         if (address >= end)
  61                 BUG();
  62         do {
  63                 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
  64                 if (!pte)
  65                         return -ENOMEM;
  66                 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
  67                 address = (address + PMD_SIZE) & PMD_MASK;
  68                 pmd++;
  69         } while (address && (address < end));
  70         return 0;
  71 }
  72
  73 static inline int remap_area_pud(pud_t * pud, unsigned long address, unsigned long size,
  74         unsigned long phys_addr, unsigned long flags)
  75 {
  76         unsigned long end;
  77
  78         address &= ~PGDIR_MASK;
  79         end = address + size;
  80         if (end > PGDIR_SIZE)
  81                 end = PGDIR_SIZE;
  82         phys_addr -= address;
  83         if (address >= end)
  84                 BUG();
  85         do {
  86                 pmd_t * pmd = pmd_alloc(&init_mm, pud, address);
  87                 if (!pmd)
  88                         return -ENOMEM;
  89                 remap_area_pmd(pmd, address, end - address, address + phys_addr, flags);
  90                 address = (address + PUD_SIZE) & PUD_MASK;
  91                 pud++;
  92         } while (address && (address < end));
  93         return 0;
  94 }
  95
  96 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  97                                  unsigned long size, unsigned long flags)
  98 {
  99         int error;
 100         pgd_t *pgd;
 101         unsigned long end = address + size;
 102
 103         phys_addr -= address;
 104         pgd = pgd_offset_k(address);
 105         flush_cache_all();
 106         if (address >= end)
 107                 BUG();
 108         spin_lock(&init_mm.page_table_lock);
 109         do {
 110                 pud_t *pud;
 111                 pud = pud_alloc(&init_mm, pgd, address);
 112                 error = -ENOMEM;
 113                 if (!pud)
 114                         break;
 115                 if (remap_area_pud(pud, address, end - address,
 116                                          phys_addr + address, flags))
 117                         break;
 118                 error = 0;
 119                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 120                 pgd++;
 121         } while (address && (address < end));
 122         spin_unlock(&init_mm.page_table_lock);
 123         flush_tlb_all();
 124         return error;
 125 }
 126
 127 /*
 128  * Fix up the linear direct mapping of the kernel to avoid cache attribute
 129  * conflicts.
 130  */
 131 static int
 132 ioremap_change_attr(unsigned long phys_addr, unsigned long size,
 133                                         unsigned long flags)
 134 {
 135         int err = 0;
 136         if (flags && phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
 137                 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 138                 unsigned long vaddr = (unsigned long) __va(phys_addr);
 139
 140                 /*
 141                  * Must use a address here and not struct page because the phys addr
 142                  * can be a in hole between nodes and not have an memmap entry.
 143                  */
 144                 err = change_page_attr_addr(vaddr,npages,__pgprot(__PAGE_KERNEL|flags));
 145                 if (!err)
 146                         global_flush_tlb();
 147         }
 148         return err;
 149 }
 150
 151 /*
 152  * Generic mapping function
 153  */
 154
 155 /*
 156  * Remap an arbitrary physical address space into the kernel virtual
 157  * address space. Needed when the kernel wants to access high addresses
 158  * directly.
 159  *
 160  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 161  * have to convert them into an offset in a page-aligned mapping, but the
 162  * caller shouldn't need to know that small detail.
 163  */
 164 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 165 {
 166         void * addr;
 167         struct vm_struct * area;
 168         unsigned long offset, last_addr;
 169
 170         /* Don't allow wraparound or zero size */
 171         last_addr = phys_addr + size - 1;
 172         if (!size || last_addr < phys_addr)
 173                 return NULL;
 174
 175         /*
 176          * Don't remap the low PCI/ISA area, it's always mapped..
 177          */
 178         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 179                 return (__force void __iomem *)phys_to_virt(phys_addr);
 180
 181 #ifndef CONFIG_DISCONTIGMEM
 182         /*
 183          * Don't allow anybody to remap normal RAM that we're using..
 184          */
 185         if (last_addr < virt_to_phys(high_memory)) {
 186                 char *t_addr, *t_end;
 187                 struct page *page;
 188
 189                 t_addr = __va(phys_addr);
 190                 t_end = t_addr + (size - 1);
 191
 192                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 193                         if(!PageReserved(page))
 194                                 return NULL;
 195         }
 196 #endif
 197
 198         /*
 199          * Mappings have to be page-aligned
 200          */
 201         offset = phys_addr & ~PAGE_MASK;
 202         phys_addr &= PAGE_MASK;
 203         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 204
 205         /*
 206          * Ok, go for it..
 207          */
 208         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 209         if (!area)
 210                 return NULL;
 211         area->phys_addr = phys_addr;
 212         addr = area->addr;
 213         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 214                 remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
 215                 return NULL;
 216         }
 217         if (ioremap_change_attr(phys_addr, size, flags) < 0) {
 218                 area->flags &= 0xffffff;
 219                 vunmap(addr);
 220                 return NULL;
 221         }
 222         return (__force void __iomem *) (offset + (char *)addr);
 223 }
 224
 225 /**
 226  * ioremap_nocache     -   map bus memory into CPU space
 227  * @offset:    bus address of the memory
 228  * @size:      size of the resource to map
 229  *
 230  * ioremap_nocache performs a platform specific sequence of operations to
 231  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 232  * writew/writel functions and the other mmio helpers. The returned
 233  * address is not guaranteed to be usable directly as a virtual
 234  * address.
 235  *
 236  * This version of ioremap ensures that the memory is marked uncachable
 237  * on the CPU as well as honouring existing caching rules from things like
 238  * the PCI bus. Note that there are other caches and buffers on many
 239  * busses. In particular driver authors should read up on PCI writes
 240  *
 241  * It's useful if some control registers are in such an area and
 242  * write combining or read caching is not desirable:
 243  *
 244  * Must be freed with iounmap.
 245  */
 246
 247 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 248 {
 249         return __ioremap(phys_addr, size, _PAGE_PCD);
 250 }
 251
 252 void iounmap(volatile void __iomem *addr)
 253 {
 254         struct vm_struct *p, **pprev;
 255
 256         if (addr <= high_memory)
 257                 return;
 258         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 259                 addr < phys_to_virt(ISA_END_ADDRESS))
 260                 return;
 261
 262         write_lock(&vmlist_lock);
 263         for (p = vmlist, pprev = &vmlist; p != NULL; pprev = &p->next, p = *pprev)
 264                 if (p->addr == (void *)(PAGE_MASK & (unsigned long)addr))
 265                         break;
 266         if (!p) {
 267                 printk("__iounmap: bad address %p\n", addr);
 268                 goto out_unlock;
 269         }
 270         *pprev = p->next;
 271         unmap_vm_area(p);
 272         if ((p->flags >> 20) &&
 273                 p->phys_addr + p->size - 1 < virt_to_phys(high_memory)) {
 274                 /* p->size includes the guard page, but cpa doesn't like that */
 275                 change_page_attr(virt_to_page(__va(p->phys_addr)),
 276                                  p->size >> PAGE_SHIFT,
 277                                  PAGE_KERNEL);
 278                 global_flush_tlb();
 279         }
 280 out_unlock:
 281         write_unlock(&vmlist_lock);
 282         kfree(p);
 283 }