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                                pgprot_t prot)
  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, prot);
  54
  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 __iomem *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);
 101         if (!area)
 102                 return NULL;
 103         area->phys_addr = phys_addr;
 104         addr = (void __iomem *) 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 (ioremap_change_attr(phys_addr, size, pgprot) < 0) {
 111                 vunmap(addr);
 112                 return NULL;
 113         }
 114         return (void __iomem *) (offset + (char __iomem *)addr);
 115 }
 116 EXPORT_SYMBOL(__ioremap);
 117
 118 /**
 119  * ioremap_nocache     -   map bus memory into CPU space
 120  * @offset:    bus address of the memory
 121  * @size:      size of the resource to map
 122  *
 123  * ioremap_nocache performs a platform specific sequence of operations to
 124  * make bus memory CPU accessible via the readb/readw/readl/writeb/
 125  * writew/writel functions and the other mmio helpers. The returned
 126  * address is not guaranteed to be usable directly as a virtual
 127  * address.
 128  *
 129  * This version of ioremap ensures that the memory is marked uncachable
 130  * on the CPU as well as honouring existing caching rules from things like
 131  * the PCI bus. Note that there are other caches and buffers on many
 132  * busses. In particular driver authors should read up on PCI writes
 133  *
 134  * It's useful if some control registers are in such an area and
 135  * write combining or read caching is not desirable:
 136  *
 137  * Must be freed with iounmap.
 138  */
 139 void __iomem *ioremap_nocache(unsigned long phys_addr, unsigned long size)
 140 {
 141         return __ioremap(phys_addr, size, _PAGE_PCD | _PAGE_PWT);
 142 }
 143 EXPORT_SYMBOL(ioremap_nocache);
 144
 145 /**
 146  * iounmap - Free a IO remapping
 147  * @addr: virtual address from ioremap_*
 148  *
 149  * Caller must ensure there is only one unmapping for the same pointer.
 150  */
 151 void iounmap(volatile void __iomem *addr)
 152 {
 153         struct vm_struct *p, *o;
 154
 155         if ((void __force *)addr <= high_memory)
 156                 return;
 157         if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
 158             addr < phys_to_virt(ISA_END_ADDRESS))
 159                 return;
 160
 161         addr = (volatile void __iomem *)
 162                 (PAGE_MASK & (unsigned long __force)addr);
 163         /* Use the vm area unlocked, assuming the caller
 164            ensures there isn't another iounmap for the same address
 165            in parallel. Reuse of the virtual address is prevented by
 166            leaving it in the global lists until we're done with it.
 167            cpa takes care of the direct mappings. */
 168         read_lock(&vmlist_lock);
 169         for (p = vmlist; p; p = p->next) {
 170                 if (p->addr == addr)
 171                         break;
 172         }
 173         read_unlock(&vmlist_lock);
 174
 175         if (!p) {
 176                 printk(KERN_ERR "iounmap: bad address %p\n", addr);
 177                 dump_stack();
 178                 return;
 179         }
 180
 181         /* Reset the direct mapping. Can block */
 182         ioremap_change_attr(p->phys_addr, p->size, PAGE_KERNEL);
 183
 184         /* Finally remove it */
 185         o = remove_vm_area((void *)addr);
 186         BUG_ON(p != o || o == NULL);
 187         kfree(p);
 188 }
 189 EXPORT_SYMBOL(iounmap);
 190