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  * x86_32 and x86_64 integration by Gustavo F. Padovan, February 2009
12  * Break out common bits to asm-generic by Mark Salter, November 2013
13  */
14 
15 #ifndef __ASM_GENERIC_FIXMAP_H
16 #define __ASM_GENERIC_FIXMAP_H
17 
18 #include <linux/bug.h>
19 #include <linux/mm_types.h>
20 
21 #define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))
22 #define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)
23 
24 #ifndef __ASSEMBLY__
25 /*
26  * 'index to address' translation. If anyone tries to use the idx
27  * directly without translation, we catch the bug with a NULL-deference
28  * kernel oops. Illegal ranges of incoming indices are caught too.
29  */
fix_to_virt(const unsigned int idx)30 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
31 {
32 	BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
33 	return __fix_to_virt(idx);
34 }
35 
virt_to_fix(const unsigned long vaddr)36 static inline unsigned long virt_to_fix(const unsigned long vaddr)
37 {
38 	BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
39 	return __virt_to_fix(vaddr);
40 }
41 
42 /*
43  * Provide some reasonable defaults for page flags.
44  * Not all architectures use all of these different types and some
45  * architectures use different names.
46  */
47 #ifndef FIXMAP_PAGE_NORMAL
48 #define FIXMAP_PAGE_NORMAL PAGE_KERNEL
49 #endif
50 #if !defined(FIXMAP_PAGE_RO) && defined(PAGE_KERNEL_RO)
51 #define FIXMAP_PAGE_RO PAGE_KERNEL_RO
52 #endif
53 #ifndef FIXMAP_PAGE_NOCACHE
54 #define FIXMAP_PAGE_NOCACHE PAGE_KERNEL_NOCACHE
55 #endif
56 #ifndef FIXMAP_PAGE_IO
57 #define FIXMAP_PAGE_IO PAGE_KERNEL_IO
58 #endif
59 #ifndef FIXMAP_PAGE_CLEAR
60 #define FIXMAP_PAGE_CLEAR __pgprot(0)
61 #endif
62 
63 #ifndef set_fixmap
64 #define set_fixmap(idx, phys)				\
65 	__set_fixmap(idx, phys, FIXMAP_PAGE_NORMAL)
66 #endif
67 
68 #ifndef clear_fixmap
69 #define clear_fixmap(idx)			\
70 	__set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR)
71 #endif
72 
73 /* Return a pointer with offset calculated */
74 #define __set_fixmap_offset(idx, phys, flags)				\
75 ({									\
76 	unsigned long ________addr;					\
77 	__set_fixmap(idx, phys, flags);					\
78 	________addr = fix_to_virt(idx) + ((phys) & (PAGE_SIZE - 1));	\
79 	________addr;							\
80 })
81 
82 #define set_fixmap_offset(idx, phys) \
83 	__set_fixmap_offset(idx, phys, FIXMAP_PAGE_NORMAL)
84 
85 /*
86  * Some hardware wants to get fixmapped without caching.
87  */
88 #define set_fixmap_nocache(idx, phys) \
89 	__set_fixmap(idx, phys, FIXMAP_PAGE_NOCACHE)
90 
91 #define set_fixmap_offset_nocache(idx, phys) \
92 	__set_fixmap_offset(idx, phys, FIXMAP_PAGE_NOCACHE)
93 
94 /*
95  * Some fixmaps are for IO
96  */
97 #define set_fixmap_io(idx, phys) \
98 	__set_fixmap(idx, phys, FIXMAP_PAGE_IO)
99 
100 #define set_fixmap_offset_io(idx, phys) \
101 	__set_fixmap_offset(idx, phys, FIXMAP_PAGE_IO)
102 
103 #endif /* __ASSEMBLY__ */
104 #endif /* __ASM_GENERIC_FIXMAP_H */
105