arch/x86/mm/ioremap_64.c

   1 /*
   2  * Re-map IO memory to kernel address space so that we can access it.
   3  * This is needed for high PCI addresses that aren't mapped in the
   4  * 640k-1MB IO memory area on PC's
   5  *
   6  * (C) Copyright 1995 1996 Linus Torvalds
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/io.h>
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/vmalloc.h>
  14
  15 #include <asm/cacheflush.h>
  16 #include <asm/e820.h>
  17 #include <asm/fixmap.h>
  18 #include <asm/pgtable.h>
  19 #include <asm/tlbflush.h>
  20
  21 unsigned long __phys_addr(unsigned long x)
  22 {
  23         if (x >= __START_KERNEL_map)
  24                 return x - __START_KERNEL_map + phys_base;
  25         return x - PAGE_OFFSET;
  26 }
  27 EXPORT_SYMBOL(__phys_addr);
  28
  29 /*
  30  * Fix up the linear direct mapping of the kernel to avoid cache attribute
  31  * conflicts.
  32  */
  33 static int ioremap_change_attr(unsigned long phys_addr, unsigned long size,
  34                                unsigned long flags)
  35 {
  36         int err = 0;
  37         if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
  38                 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
  39                 unsigned long vaddr = (unsigned long) __va(phys_addr);
  40                 int level;
  41
  42                 /*
  43                  * If there is no identity map for this address,
  44                  * change_page_attr_addr is unnecessary
  45                  */
  46                 if (!lookup_address(vaddr, &level))
  47                         return err;
  48                 /*
  49                  * Must use a address here and not struct page because
  50                  * the phys addr can be a in hole between nodes and
  51                  * not have an memmap entry.
  52                  */
  53                 err = change_page_attr_addr(vaddr,npages,
  54                                             MAKE_GLOBAL(__PAGE_KERNEL|flags));
  55                 if (!err)
  56                         global_flush_tlb();
  57         }
  58         return err;
  59 }
  60
  61 /*
  62  * Remap an arbitrary physical address space into the kernel virtual
  63  * address space. Needed when the kernel wants to access high addresses
  64  * directly.
  65  *
  66  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
  67  * have to convert them into an offset in a page-aligned mapping, but the
  68  * caller shouldn't need to know that small detail.
  69  */
  70 void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
  71                         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         pgprot = MAKE_GLOBAL(__PAGE_KERNEL | flags);
  90         /*
  91          * Mappings have to be page-aligned
  92          */
  93         offset = phys_addr & ~PAGE_MASK;
  94         phys_addr &= PAGE_MASK;
  95         size = PAGE_ALIGN(last_addr+1) - phys_addr;
  96
  97         /*
  98          * Ok, go for it..
  99          */
 100         area = get_vm_area(size, VM_IOREMAP | (flags << 20));
 101         if (!area)
 102                 return NULL;
 103         area->phys_addr = phys_addr;
 104         addr = area->addr;
 105         if (ioremap_page_range((unsigned long)addr, (unsigned long)addr + size,
 106                                phys_addr, pgprot)) {
 107                 remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
 108                 return NULL;
 109         }
 110         if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
 111                 area->flags &= 0xffffff;
 112                 vunmap(addr);
 113                 return NULL;
 114         }
 115         return (__force void __iomem *) (offset + (char *)addr);
 116 }
 117 EXPORT_SYMBOL(__ioremap);
 118
 119 /**
 120  * ioremap_nocache     -   map bus memory into CPU space
 121  * @offset:    bus address of the memory
 122  * @size:      size of the resource to map
 123  *
 124  * ioremap_nocache performs a platform specific sequence of operations to
 125  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 126  * writew/writel functions and the other mmio helpers. The returned
 127  * address is not guaranteed to be usable directly as a virtual
 128  * address.
 129  *
 130  * This version of ioremap ensures that the memory is marked uncachable
 131  * on the CPU as well as honouring existing caching rules from things like
 132  * the PCI bus. Note that there are other caches and buffers on many
 133  * busses. In particular driver authors should read up on PCI writes
 134  *
 135  * It's useful if some control registers are in such an area and
 136  * write combining or read caching is not desirable:
 137  *
 138  * Must be freed with iounmap.
 139  */
 140 void __iomem *ioremap_nocache(unsigned long phys_addr, unsigned long size)
 141 {
 142         return __ioremap(phys_addr, size, _PAGE_PCD | _PAGE_PWT);
 143 }
 144 EXPORT_SYMBOL(ioremap_nocache);
 145
 146 /**
 147  * iounmap - Free a IO remapping
 148  * @addr: virtual address from ioremap_*
 149  *
 150  * Caller must ensure there is only one unmapping for the same pointer.
 151  */
 152 void iounmap(volatile void __iomem *addr)
 153 {
 154         struct vm_struct *p, *o;
 155
 156         if (addr <= high_memory)
 157                 return;
 158         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 159             addr < phys_to_virt(ISA_END_ADDRESS))
 160                 return;
 161
 162         addr = (volatile void __iomem *)
 163                 (PAGE_MASK & (unsigned long __force)addr);
 164         /* Use the vm area unlocked, assuming the caller
 165            ensures there isn't another iounmap for the same address
 166            in parallel. Reuse of the virtual address is prevented by
 167            leaving it in the global lists until we're done with it.
 168            cpa takes care of the direct mappings. */
 169         read_lock(&vmlist_lock);
 170         for (p = vmlist; p; p = p->next) {
 171                 if (p->addr == addr)
 172                         break;
 173         }
 174         read_unlock(&vmlist_lock);
 175
 176         if (!p) {
 177                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 178                 dump_stack();
 179                 return;
 180         }
 181
 182         /* Reset the direct mapping. Can block */
 183         if (p->flags >> 20)
 184                 ioremap_change_attr(p->phys_addr, p->size, 0);
 185
 186         /* Finally remove it */
 187         o = remove_vm_area((void *)addr);
 188         BUG_ON(p != o || o == NULL);
 189         kfree(p);
 190 }
 191 EXPORT_SYMBOL(iounmap);
 192