arch/x86/mm/ioremap_64.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 <linux/module.h>
  15 #include <linux/io.h>
  16
  17 #include <asm/pgalloc.h>
  18 #include <asm/fixmap.h>
  19 #include <asm/tlbflush.h>
  20 #include <asm/cacheflush.h>
  21 #include <asm/proto.h>
  22
  23 unsigned long __phys_addr(unsigned long x)
  24 {
  25         if (x >= __START_KERNEL_map)
  26                 return x - __START_KERNEL_map + phys_base;
  27         return x - PAGE_OFFSET;
  28 }
  29 EXPORT_SYMBOL(__phys_addr);
  30
  31 #define ISA_START_ADDRESS      0xa0000
  32 #define ISA_END_ADDRESS                0x100000
  33
  34 /*
  35  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  36  * conflicts.
  37  */
  38 static int
  39 ioremap_change_attr(unsigned long phys_addr, unsigned long size,
  40                                         unsigned long flags)
  41 {
  42         int err = 0;
  43         if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
  44                 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
  45                 unsigned long vaddr = (unsigned long) __va(phys_addr);
  46
  47                 /*
  48                  * Must use a address here and not struct page because the phys addr
  49                  * can be a in hole between nodes and not have an memmap entry.
  50                  */
  51                 err = change_page_attr_addr(vaddr,npages,__pgprot(__PAGE_KERNEL|flags));
  52                 if (!err)
  53                         global_flush_tlb();
  54         }
  55         return err;
  56 }
  57
  58 /*
  59  * Generic mapping function
  60  */
  61
  62 /*
  63  * Remap an arbitrary physical address space into the kernel virtual
  64  * address space. Needed when the kernel wants to access high addresses
  65  * directly.
  66  *
  67  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  68  * have to convert them into an offset in a page-aligned mapping, but the
  69  * caller shouldn't need to know that small detail.
  70  */
  71 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
  72 {
  73         void * addr;
  74         struct vm_struct * area;
  75         unsigned long offset, last_addr;
  76         pgprot_t pgprot;
  77
  78         /* Don't allow wraparound or zero size */
  79         last_addr = phys_addr + size - 1;
  80         if (!size || last_addr < phys_addr)
  81                 return NULL;
  82
  83         /*
  84          * Don't remap the low PCI/ISA area, it's always mapped..
  85          */
  86         if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
  87                 return (__force void __iomem *)phys_to_virt(phys_addr);
  88
  89 #ifdef CONFIG_FLATMEM
  90         /*
  91          * Don't allow anybody to remap normal RAM that we're using..
  92          */
  93         if (last_addr < virt_to_phys(high_memory)) {
  94                 char *t_addr, *t_end;
  95                 struct page *page;
  96
  97                 t_addr = __va(phys_addr);
  98                 t_end = t_addr + (size - 1);
  99
 100                 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
 101                         if(!PageReserved(page))
 102                                 return NULL;
 103         }
 104 #endif
 105
 106         pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_GLOBAL
 107                           | _PAGE_DIRTY | _PAGE_ACCESSED | flags);
 108         /*
 109          * Mappings have to be page-aligned
 110          */
 111         offset = phys_addr & ~PAGE_MASK;
 112         phys_addr &= PAGE_MASK;
 113         size = PAGE_ALIGN(last_addr+1) - phys_addr;
 114
 115         /*
 116          * Ok, go for it..
 117          */
 118         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 119         if (!area)
 120                 return NULL;
 121         area->phys_addr = phys_addr;
 122         addr = area->addr;
 123         if (ioremap_page_range((unsigned long)addr, (unsigned long)addr + size,
 124                                phys_addr, pgprot)) {
 125                 remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
 126                 return NULL;
 127         }
 128         if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
 129                 area->flags &= 0xffffff;
 130                 vunmap(addr);
 131                 return NULL;
 132         }
 133         return (__force void __iomem *) (offset + (char *)addr);
 134 }
 135 EXPORT_SYMBOL(__ioremap);
 136
 137 /**
 138  * ioremap_nocache     -   map bus memory into CPU space
 139  * @offset:    bus address of the memory
 140  * @size:      size of the resource to map
 141  *
 142  * ioremap_nocache performs a platform specific sequence of operations to
 143  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 144  * writew/writel functions and the other mmio helpers. The returned
 145  * address is not guaranteed to be usable directly as a virtual
 146  * address.
 147  *
 148  * This version of ioremap ensures that the memory is marked uncachable
 149  * on the CPU as well as honouring existing caching rules from things like
 150  * the PCI bus. Note that there are other caches and buffers on many
 151  * busses. In particular driver authors should read up on PCI writes
 152  *
 153  * It's useful if some control registers are in such an area and
 154  * write combining or read caching is not desirable:
 155  *
 156  * Must be freed with iounmap.
 157  */
 158
 159 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
 160 {
 161         return __ioremap(phys_addr, size, _PAGE_PCD);
 162 }
 163 EXPORT_SYMBOL(ioremap_nocache);
 164
 165 /**
 166  * iounmap - Free a IO remapping
 167  * @addr: virtual address from ioremap_*
 168  *
 169  * Caller must ensure there is only one unmapping for the same pointer.
 170  */
 171 void iounmap(volatile void __iomem *addr)
 172 {
 173         struct vm_struct *p, *o;
 174
 175         if (addr <= high_memory)
 176                 return;
 177         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 178                 addr < phys_to_virt(ISA_END_ADDRESS))
 179                 return;
 180
 181         addr = (volatile void __iomem *)(PAGE_MASK & (unsigned long __force)addr);
 182         /* Use the vm area unlocked, assuming the caller
 183            ensures there isn't another iounmap for the same address
 184            in parallel. Reuse of the virtual address is prevented by
 185            leaving it in the global lists until we're done with it.
 186            cpa takes care of the direct mappings. */
 187         read_lock(&vmlist_lock);
 188         for (p = vmlist; p; p = p->next) {
 189                 if (p->addr == addr)
 190                         break;
 191         }
 192         read_unlock(&vmlist_lock);
 193
 194         if (!p) {
 195                 printk("iounmap: bad address %p\n", addr);
 196                 dump_stack();
 197                 return;
 198         }
 199
 200         /* Reset the direct mapping. Can block */
 201         if (p->flags >> 20)
 202                 ioremap_change_attr(p->phys_addr, p->size, 0);
 203
 204         /* Finally remove it */
 205         o = remove_vm_area((void *)addr);
 206         BUG_ON(p != o || o == NULL);
 207         kfree(p);
 208 }
 209 EXPORT_SYMBOL(iounmap);
 210