1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * (C) Copyright 1995 1996 Linus Torvalds
4 * (C) Copyright 2012 Regents of the University of California
5 */
6
7 #include <linux/export.h>
8 #include <linux/mm.h>
9 #include <linux/vmalloc.h>
10 #include <linux/io.h>
11
12 #include <asm/pgtable.h>
13
14 /*
15 * Remap an arbitrary physical address space into the kernel virtual
16 * address space. Needed when the kernel wants to access high addresses
17 * directly.
18 *
19 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
20 * have to convert them into an offset in a page-aligned mapping, but the
21 * caller shouldn't need to know that small detail.
22 */
23 static void __iomem *__ioremap_caller(phys_addr_t addr, size_t size,
24 pgprot_t prot, void *caller)
25 {
26 phys_addr_t last_addr;
27 unsigned long offset, vaddr;
28 struct vm_struct *area;
29
30 /* Disallow wrap-around or zero size */
31 last_addr = addr + size - 1;
32 if (!size || last_addr < addr)
33 return NULL;
34
35 /* Page-align mappings */
36 offset = addr & (~PAGE_MASK);
37 addr -= offset;
38 size = PAGE_ALIGN(size + offset);
39
40 area = get_vm_area_caller(size, VM_IOREMAP, caller);
41 if (!area)
42 return NULL;
43 vaddr = (unsigned long)area->addr;
44
45 if (ioremap_page_range(vaddr, vaddr + size, addr, prot)) {
46 free_vm_area(area);
47 return NULL;
48 }
49
50 return (void __iomem *)(vaddr + offset);
51 }
52
53 /*
54 * ioremap - map bus memory into CPU space
55 * @offset: bus address of the memory
56 * @size: size of the resource to map
57 *
58 * ioremap performs a platform specific sequence of operations to
59 * make bus memory CPU accessible via the readb/readw/readl/writeb/
60 * writew/writel functions and the other mmio helpers. The returned
61 * address is not guaranteed to be usable directly as a virtual
62 * address.
63 *
64 * Must be freed with iounmap.
65 */
66 void __iomem *ioremap(phys_addr_t offset, unsigned long size)
67 {
68 return __ioremap_caller(offset, size, PAGE_KERNEL,
69 __builtin_return_address(0));
70 }
71 EXPORT_SYMBOL(ioremap);
72
73
74 /**
75 * iounmap - Free a IO remapping
76 * @addr: virtual address from ioremap_*
77 *
78 * Caller must ensure there is only one unmapping for the same pointer.
79 */
80 void iounmap(volatile void __iomem *addr)
81 {
82 vunmap((void *)((unsigned long)addr & PAGE_MASK));
83 }
84 EXPORT_SYMBOL(iounmap);