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(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         do {
 109                 pud_t *pud;
 110                 pud = pud_alloc(&init_mm, pgd, address);
 111                 error = -ENOMEM;
 112                 if (!pud)
 113                         break;
 114                 if (remap_area_pud(pud, address, end - address,
 115                                          phys_addr + address, flags))
 116                         break;
 117                 error = 0;
 118                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 119                 pgd++;
 120         } while (address && (address < end));
 121         flush_tlb_all();
 122         return error;
 123 }
 124
 125 /*
 126  * Fix up the linear direct mapping of the kernel to avoid cache attribute
 127  * conflicts.
 128  */
 129 static int
 130 ioremap_change_attr(unsigned long phys_addr, unsigned long size,
 131                                         unsigned long flags)
 132 {
 133         int err = 0;
 134         if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
 135                 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 136                 unsigned long vaddr = (unsigned long) __va(phys_addr);
 137
 138                 /*
 139                  * Must use a address here and not struct page because the phys addr
 140                  * can be a in hole between nodes and not have an memmap entry.
 141                  */
 142                 err = change_page_attr_addr(vaddr,npages,__pgprot(__PAGE_KERNEL|flags));
 143                 if (!err)
 144                         global_flush_tlb();
 145         }
 146         return err;
 147 }
 148
 149 /*
 150  * Generic mapping function
 151  */
 152
 153 /*
 154  * Remap an arbitrary physical address space into the kernel virtual
 155  * address space. Needed when the kernel wants to access high addresses
 156  * directly.
 157  *
 158  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 159  * have to convert them into an offset in a page-aligned mapping, but the
 160  * caller shouldn't need to know that small detail.
 161  */
 162 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
 163 {
 164         void * addr;
 165         struct vm_struct * area;
 166         unsigned long offset, last_addr;
 167
 168         /* Don't allow wraparound or zero size */
 169         last_addr = phys_addr + size - 1;
 170         if (!size || last_addr < phys_addr)
 171                 return NULL;
 172
 173         /*
 174          * Don't remap the low PCI/ISA area, it's always mapped..
 175          */
 176         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
 177                 return (__force void __iomem *)phys_to_virt(phys_addr);
 178
 179 #ifdef CONFIG_FLATMEM
 180         /*
 181          * Don't allow anybody to remap normal RAM that we're using..
 182          */
 183         if (last_addr < virt_to_phys(high_memory)) {
 184                 char *t_addr, *t_end;
 185                 struct page *page;
 186
 187                 t_addr = __va(phys_addr);
 188                 t_end = t_addr + (size - 1);
 189
 190                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 191                         if(!PageReserved(page))
 192                                 return NULL;
 193         }
 194 #endif
 195
 196         /*
 197          * Mappings have to be page-aligned
 198          */
 199         offset = phys_addr & ~PAGE_MASK;
 200         phys_addr &= PAGE_MASK;
 201         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 202
 203         /*
 204          * Ok, go for it..
 205          */
 206         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 207         if (!area)
 208                 return NULL;
 209         area->phys_addr = phys_addr;
 210         addr = area->addr;
 211         if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
 212                 remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
 213                 return NULL;
 214         }
 215         if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
 216                 area->flags &= 0xffffff;
 217                 vunmap(addr);
 218                 return NULL;
 219         }
 220         return (__force void __iomem *) (offset + (char *)addr);
 221 }
 222
 223 /**
 224  * ioremap_nocache     -   map bus memory into CPU space
 225  * @offset:    bus address of the memory
 226  * @size:      size of the resource to map
 227  *
 228  * ioremap_nocache performs a platform specific sequence of operations to
 229  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 230  * writew/writel functions and the other mmio helpers. The returned
 231  * address is not guaranteed to be usable directly as a virtual
 232  * address.
 233  *
 234  * This version of ioremap ensures that the memory is marked uncachable
 235  * on the CPU as well as honouring existing caching rules from things like
 236  * the PCI bus. Note that there are other caches and buffers on many
 237  * busses. In particular driver authors should read up on PCI writes
 238  *
 239  * It's useful if some control registers are in such an area and
 240  * write combining or read caching is not desirable:
 241  *
 242  * Must be freed with iounmap.
 243  */
 244
 245 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 246 {
 247         return __ioremap(phys_addr, size, _PAGE_PCD);
 248 }
 249
 250 void iounmap(volatile void __iomem *addr)
 251 {
 252         struct vm_struct *p;
 253
 254         if (addr <= high_memory)
 255                 return;
 256         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 257                 addr < phys_to_virt(ISA_END_ADDRESS))
 258                 return;
 259
 260         write_lock(&vmlist_lock);
 261         p = __remove_vm_area((void *)((unsigned long)addr & PAGE_MASK));
 262         if (!p)
 263                 printk("iounmap: bad address %p\n", addr);
 264         else if (p->flags >> 20)
 265                 ioremap_change_attr(p->phys_addr, p->size, 0);
 266         write_unlock(&vmlist_lock);
 267         kfree(p);
 268 }