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1/*
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 * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
11 */
12
13#ifndef _ASM_FIXMAP_H
14#define _ASM_FIXMAP_H
15
16#include <asm/page.h>
17#ifdef CONFIG_HIGHMEM
18#include <linux/threads.h>
19#include <asm/kmap_types.h>
20#endif
21
22/*
23 * Here we define all the compile-time 'special' virtual
24 * addresses. The point is to have a constant address at
25 * compile time, but to set the physical address only
26 * in the boot process. We allocate these special addresses
27 * from the end of virtual memory (0xfffff000) backwards.
28 * Also this lets us do fail-safe vmalloc(), we
29 * can guarantee that these special addresses and
30 * vmalloc()-ed addresses never overlap.
31 *
32 * these 'compile-time allocated' memory buffers are
33 * fixed-size 4k pages. (or larger if used with an increment
34 * highger than 1) use fixmap_set(idx,phys) to associate
35 * physical memory with fixmap indices.
36 *
37 * TLB entries of such buffers will not be flushed across
38 * task switches.
39 */
40
41/*
42 * on UP currently we will have no trace of the fixmap mechanizm,
43 * no page table allocations, etc. This might change in the
44 * future, say framebuffers for the console driver(s) could be
45 * fix-mapped?
46 */
47enum fixed_addresses {
48#ifdef CONFIG_HIGHMEM
49 FIX_KMAP_BEGIN, /* reserved pte's for temporary kernel mappings */
50 FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
51#endif
52 __end_of_fixed_addresses
53};
54
55extern void __set_fixmap (enum fixed_addresses idx,
56 unsigned long 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 * used by vmalloc.c.
67 *
68 * Leave one empty page between vmalloc'ed areas and
69 * the start of the fixmap, and leave one page empty
70 * at the top of mem..
71 */
72#if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
73#define FIXADDR_TOP (0xff000000UL - 0x2000)
74#else
75#define FIXADDR_TOP (0xffffe000UL)
76#endif
77#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
78#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
79
80#define __fix_to_virt(x) (FIXADDR_TOP - ((x) << PAGE_SHIFT))
81#define __virt_to_fix(x) ((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
82
83extern void __this_fixmap_does_not_exist(void);
84
85/*
86 * 'index to address' translation. If anyone tries to use the idx
87 * directly without tranlation, we catch the bug with a NULL-deference
88 * kernel oops. Illegal ranges of incoming indices are caught too.
89 */
90static inline unsigned long fix_to_virt(const unsigned int idx)
91{
92 /*
93 * this branch gets completely eliminated after inlining,
94 * except when someone tries to use fixaddr indices in an
95 * illegal way. (such as mixing up address types or using
96 * out-of-range indices).
97 *
98 * If it doesn't get removed, the linker will complain
99 * loudly with a reasonably clear error message..
100 */
101 if (idx >= __end_of_fixed_addresses)
102 __this_fixmap_does_not_exist();
103
104 return __fix_to_virt(idx);
105}
106
107static inline unsigned long virt_to_fix(const unsigned long vaddr)
108{
109 BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
110 return __virt_to_fix(vaddr);
111}
112
113/*
114 * Called from pgtable_init()
115 */
116extern void fixrange_init(unsigned long start, unsigned long end,
117 pgd_t *pgd_base);
118
119
120#endif