2 * arch/x86_64/mm/ioremap.c
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
8 * (C) Copyright 1995 1996 Linus Torvalds
11 #include <linux/vmalloc.h>
12 #include <linux/init.h>
13 #include <linux/slab.h>
14 #include <linux/module.h>
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>
24 unsigned long __phys_addr(unsigned long x)
26 if (x >= __START_KERNEL_map)
27 return x - __START_KERNEL_map + phys_base;
28 return x - PAGE_OFFSET;
30 EXPORT_SYMBOL(__phys_addr);
33 * Fix up the linear direct mapping of the kernel to avoid cache attribute
37 ioremap_change_attr(unsigned long phys_addr, unsigned long size,
41 if (phys_addr + size - 1 < (end_pfn_map << PAGE_SHIFT)) {
42 unsigned long npages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
43 unsigned long vaddr = (unsigned long) __va(phys_addr);
46 * Must use a address here and not struct page because the phys addr
47 * can be a in hole between nodes and not have an memmap entry.
49 err = change_page_attr_addr(vaddr,npages,__pgprot(__PAGE_KERNEL|flags));
57 * Generic mapping function
61 * Remap an arbitrary physical address space into the kernel virtual
62 * address space. Needed when the kernel wants to access high addresses
65 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
66 * have to convert them into an offset in a page-aligned mapping, but the
67 * caller shouldn't need to know that small detail.
69 void __iomem * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
72 struct vm_struct * area;
73 unsigned long offset, last_addr;
76 /* Don't allow wraparound or zero size */
77 last_addr = phys_addr + size - 1;
78 if (!size || last_addr < phys_addr)
82 * Don't remap the low PCI/ISA area, it's always mapped..
84 if (phys_addr >= ISA_START_ADDRESS && last_addr < ISA_END_ADDRESS)
85 return (__force void __iomem *)phys_to_virt(phys_addr);
87 pgprot = __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_GLOBAL
88 | _PAGE_DIRTY | _PAGE_ACCESSED | flags);
90 * Mappings have to be page-aligned
92 offset = phys_addr & ~PAGE_MASK;
93 phys_addr &= PAGE_MASK;
94 size = PAGE_ALIGN(last_addr+1) - phys_addr;
99 area = get_vm_area(size, VM_IOREMAP | (flags << 20));
102 area->phys_addr = phys_addr;
104 if (ioremap_page_range((unsigned long)addr, (unsigned long)addr + size,
105 phys_addr, pgprot)) {
106 remove_vm_area((void *)(PAGE_MASK & (unsigned long) addr));
109 if (flags && ioremap_change_attr(phys_addr, size, flags) < 0) {
110 area->flags &= 0xffffff;
114 return (__force void __iomem *) (offset + (char *)addr);
116 EXPORT_SYMBOL(__ioremap);
119 * ioremap_nocache - map bus memory into CPU space
120 * @offset: bus address of the memory
121 * @size: size of the resource to map
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
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
134 * It's useful if some control registers are in such an area and
135 * write combining or read caching is not desirable:
137 * Must be freed with iounmap.
140 void __iomem *ioremap_nocache (unsigned long phys_addr, unsigned long size)
142 return __ioremap(phys_addr, size, _PAGE_PCD);
144 EXPORT_SYMBOL(ioremap_nocache);
147 * iounmap - Free a IO remapping
148 * @addr: virtual address from ioremap_*
150 * Caller must ensure there is only one unmapping for the same pointer.
152 void iounmap(volatile void __iomem *addr)
154 struct vm_struct *p, *o;
156 if (addr <= high_memory)
158 if (addr >= phys_to_virt(ISA_START_ADDRESS) &&
159 addr < phys_to_virt(ISA_END_ADDRESS))
162 addr = (volatile void __iomem *)(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) {
173 read_unlock(&vmlist_lock);
176 printk("iounmap: bad address %p\n", addr);
181 /* Reset the direct mapping. Can block */
183 ioremap_change_attr(p->phys_addr, p->size, 0);
185 /* Finally remove it */
186 o = remove_vm_area((void *)addr);
187 BUG_ON(p != o || o == NULL);
190 EXPORT_SYMBOL(iounmap);