blob: 8428b38a3d30342087581fbfa49702724cded54c [file] [log] [blame]
Kumar Gala2c419bd2008-04-23 23:05:20 +10001/*
2 * fixmap.h: compile-time virtual memory allocation
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 1998 Ingo Molnar
9 *
10 * Copyright 2008 Freescale Semiconductor Inc.
11 * Port to powerpc added by Kumar Gala
12 */
13
14#ifndef _ASM_FIXMAP_H
15#define _ASM_FIXMAP_H
16
17extern unsigned long FIXADDR_TOP;
18
19#ifndef __ASSEMBLY__
20#include <linux/kernel.h>
21#include <asm/page.h>
22#ifdef CONFIG_HIGHMEM
23#include <linux/threads.h>
24#include <asm/kmap_types.h>
25#endif
26
27/*
28 * Here we define all the compile-time 'special' virtual
29 * addresses. The point is to have a constant address at
30 * compile time, but to set the physical address only
31 * in the boot process. We allocate these special addresses
32 * from the end of virtual memory (0xfffff000) backwards.
33 * Also this lets us do fail-safe vmalloc(), we
34 * can guarantee that these special addresses and
35 * vmalloc()-ed addresses never overlap.
36 *
37 * these 'compile-time allocated' memory buffers are
38 * fixed-size 4k pages. (or larger if used with an increment
39 * highger than 1) use fixmap_set(idx,phys) to associate
40 * physical memory with fixmap indices.
41 *
42 * TLB entries of such buffers will not be flushed across
43 * task switches.
44 */
45enum fixed_addresses {
46 FIX_HOLE,
47#ifdef CONFIG_HIGHMEM
48 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
49 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
50#endif
51 /* FIX_PCIE_MCFG, */
52 __end_of_fixed_addresses
53};
54
55extern void __set_fixmap (enum fixed_addresses idx,
56 phys_addr_t phys, pgprot_t flags);
57
58#define set_fixmap(idx, phys) \
59 __set_fixmap(idx, phys, PAGE_KERNEL)
60/*
61 * Some hardware wants to get fixmapped without caching.
62 */
63#define set_fixmap_nocache(idx, phys) \
64 __set_fixmap(idx, phys, PAGE_KERNEL_NOCACHE)
65
66#define clear_fixmap(idx) \
67 __set_fixmap(idx, 0, __pgprot(0))
68
69#define __FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
70#define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
71
72#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
73#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
74
75extern void __this_fixmap_does_not_exist(void);
76
77/*
78 * 'index to address' translation. If anyone tries to use the idx
79 * directly without tranlation, we catch the bug with a NULL-deference
80 * kernel oops. Illegal ranges of incoming indices are caught too.
81 */
82static __always_inline unsigned long fix_to_virt(const unsigned int idx)
83{
84 /*
85 * this branch gets completely eliminated after inlining,
86 * except when someone tries to use fixaddr indices in an
87 * illegal way. (such as mixing up address types or using
88 * out-of-range indices).
89 *
90 * If it doesn't get removed, the linker will complain
91 * loudly with a reasonably clear error message..
92 */
93 if (idx >= __end_of_fixed_addresses)
94 __this_fixmap_does_not_exist();
95
96 return __fix_to_virt(idx);
97}
98
99static inline unsigned long virt_to_fix(const unsigned long vaddr)
100{
101 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
102 return __virt_to_fix(vaddr);
103}
104
105#endif /* !__ASSEMBLY__ */
106#endif