1 /*
2 * Copyright © 2008 Keith Packard <keithp@keithp.com>
3 *
4 * This file is free software; you can redistribute it and/or modify
5 * it under the terms of version 2 of the GNU General Public License
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
16 */
17
18 #ifndef _LINUX_IO_MAPPING_H
19 #define _LINUX_IO_MAPPING_H
20
21 #include <linux/types.h>
22 #include <asm/io.h>
23 #include <asm/page.h>
24 #include <asm/iomap.h>
25
26 /*
27 * The io_mapping mechanism provides an abstraction for mapping
28 * individual pages from an io device to the CPU in an efficient fashion.
29 *
30 * See Documentation/io_mapping.txt
31 */
32
33 #ifdef CONFIG_HAVE_ATOMIC_IOMAP
34
35 struct io_mapping {
36 resource_size_t base;
37 unsigned long size;
38 pgprot_t prot;
39 };
40
41 /*
42 * For small address space machines, mapping large objects
43 * into the kernel virtual space isn't practical. Where
44 * available, use fixmap support to dynamically map pages
45 * of the object at run time.
46 */
47
48 static inline struct io_mapping *
io_mapping_create_wc(resource_size_t base,unsigned long size)49 io_mapping_create_wc(resource_size_t base, unsigned long size)
50 {
51 struct io_mapping *iomap;
52
53 if (!is_io_mapping_possible(base, size))
54 return NULL;
55
56 iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
57 if (!iomap)
58 return NULL;
59
60 iomap->base = base;
61 iomap->size = size;
62 iomap->prot = pgprot_writecombine(__pgprot(__PAGE_KERNEL));
63 return iomap;
64 }
65
66 static inline void
io_mapping_free(struct io_mapping * mapping)67 io_mapping_free(struct io_mapping *mapping)
68 {
69 kfree(mapping);
70 }
71
72 /* Atomic map/unmap */
73 static inline void *
io_mapping_map_atomic_wc(struct io_mapping * mapping,unsigned long offset)74 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
75 {
76 resource_size_t phys_addr;
77 unsigned long pfn;
78
79 BUG_ON(offset >= mapping->size);
80 phys_addr = mapping->base + offset;
81 pfn = (unsigned long) (phys_addr >> PAGE_SHIFT);
82 return iomap_atomic_prot_pfn(pfn, KM_USER0, mapping->prot);
83 }
84
85 static inline void
io_mapping_unmap_atomic(void * vaddr)86 io_mapping_unmap_atomic(void *vaddr)
87 {
88 iounmap_atomic(vaddr, KM_USER0);
89 }
90
91 static inline void *
io_mapping_map_wc(struct io_mapping * mapping,unsigned long offset)92 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
93 {
94 resource_size_t phys_addr;
95
96 BUG_ON(offset >= mapping->size);
97 phys_addr = mapping->base + offset;
98
99 return ioremap_wc(phys_addr, PAGE_SIZE);
100 }
101
102 static inline void
io_mapping_unmap(void * vaddr)103 io_mapping_unmap(void *vaddr)
104 {
105 iounmap(vaddr);
106 }
107
108 #else
109
110 /* this struct isn't actually defined anywhere */
111 struct io_mapping;
112
113 /* Create the io_mapping object*/
114 static inline struct io_mapping *
io_mapping_create_wc(resource_size_t base,unsigned long size)115 io_mapping_create_wc(resource_size_t base, unsigned long size)
116 {
117 return (struct io_mapping *) ioremap_wc(base, size);
118 }
119
120 static inline void
io_mapping_free(struct io_mapping * mapping)121 io_mapping_free(struct io_mapping *mapping)
122 {
123 iounmap(mapping);
124 }
125
126 /* Atomic map/unmap */
127 static inline void *
io_mapping_map_atomic_wc(struct io_mapping * mapping,unsigned long offset)128 io_mapping_map_atomic_wc(struct io_mapping *mapping, unsigned long offset)
129 {
130 return ((char *) mapping) + offset;
131 }
132
133 static inline void
io_mapping_unmap_atomic(void * vaddr)134 io_mapping_unmap_atomic(void *vaddr)
135 {
136 }
137
138 /* Non-atomic map/unmap */
139 static inline void *
io_mapping_map_wc(struct io_mapping * mapping,unsigned long offset)140 io_mapping_map_wc(struct io_mapping *mapping, unsigned long offset)
141 {
142 return ((char *) mapping) + offset;
143 }
144
145 static inline void
io_mapping_unmap(void * vaddr)146 io_mapping_unmap(void *vaddr)
147 {
148 }
149
150 #endif /* HAVE_ATOMIC_IOMAP */
151
152 #endif /* _LINUX_IO_MAPPING_H */
153