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
6 * (C) Copyright 1995 1996 Linus Torvalds
9 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/vmalloc.h>
15 #include <asm/cacheflush.h>
17 #include <asm/fixmap.h>
18 #include <asm/pgtable.h>
19 #include <asm/tlbflush.h>
21 unsigned long __phys_addr(unsigned long x
)
23 if (x
>= __START_KERNEL_map
)
24 return x
- __START_KERNEL_map
+ phys_base
;
25 return x
- PAGE_OFFSET
;
27 EXPORT_SYMBOL(__phys_addr
);
30 * Fix up the linear direct mapping of the kernel to avoid cache attribute
33 static int ioremap_change_attr(unsigned long phys_addr
, unsigned long size
,
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
);
43 * If there is no identity map for this address,
44 * change_page_attr_addr is unnecessary
46 if (!lookup_address(vaddr
, &level
))
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.
53 err
= change_page_attr_addr(vaddr
, npages
, prot
);
62 * Remap an arbitrary physical address space into the kernel virtual
63 * address space. Needed when the kernel wants to access high addresses
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.
70 void __iomem
*__ioremap(unsigned long phys_addr
, unsigned long size
,
74 struct vm_struct
*area
;
75 unsigned long offset
, last_addr
;
78 /* Don't allow wraparound or zero size */
79 last_addr
= phys_addr
+ size
- 1;
80 if (!size
|| last_addr
< phys_addr
)
84 * Don't remap the low PCI/ISA area, it's always mapped..
86 if (phys_addr
>= ISA_START_ADDRESS
&& last_addr
< ISA_END_ADDRESS
)
87 return (__force
void __iomem
*)phys_to_virt(phys_addr
);
89 pgprot
= MAKE_GLOBAL(__PAGE_KERNEL
| flags
);
91 * Mappings have to be page-aligned
93 offset
= phys_addr
& ~PAGE_MASK
;
94 phys_addr
&= PAGE_MASK
;
95 size
= PAGE_ALIGN(last_addr
+1) - phys_addr
;
100 area
= get_vm_area(size
, VM_IOREMAP
);
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
));
110 if (ioremap_change_attr(phys_addr
, size
, pgprot
) < 0) {
114 return (void __iomem
*) (offset
+ (char __iomem
*)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.
139 void __iomem
*ioremap_nocache(unsigned long phys_addr
, unsigned long size
)
141 return __ioremap(phys_addr
, size
, _PAGE_PCD
| _PAGE_PWT
);
143 EXPORT_SYMBOL(ioremap_nocache
);
146 * iounmap - Free a IO remapping
147 * @addr: virtual address from ioremap_*
149 * Caller must ensure there is only one unmapping for the same pointer.
151 void iounmap(volatile void __iomem
*addr
)
153 struct vm_struct
*p
, *o
;
155 if ((void __force
*)addr
<= high_memory
)
157 if (addr
>= phys_to_virt(ISA_START_ADDRESS
) &&
158 addr
< phys_to_virt(ISA_END_ADDRESS
))
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
) {
173 read_unlock(&vmlist_lock
);
176 printk(KERN_ERR
"iounmap: bad address %p\n", addr
);
181 /* Reset the direct mapping. Can block */
182 ioremap_change_attr(p
->phys_addr
, p
->size
, PAGE_KERNEL
);
184 /* Finally remove it */
185 o
= remove_vm_area((void *)addr
);
186 BUG_ON(p
!= o
|| o
== NULL
);
189 EXPORT_SYMBOL(iounmap
);