1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
#ifndef __LINUX_CMA_H
#define __LINUX_CMA_H
/*
* Contiguous Memory Allocator for DMA mapping framework
* Copyright (c) 2010-2011 by Samsung Electronics.
* Written by:
* Marek Szyprowski <m.szyprowski@samsung.com>
* Michal Nazarewicz <mina86@mina86.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License or (at your optional) any later version of the license.
*/
/*
* Contiguous Memory Allocator
*
* The Contiguous Memory Allocator (CMA) makes it possible to
* allocate big contiguous chunks of memory after the system has
* booted.
*
* Why is it needed?
*
* Various devices on embedded systems have no scatter-getter and/or
* IO map support and require contiguous blocks of memory to
* operate. They include devices such as cameras, hardware video
* coders, etc.
*
* Such devices often require big memory buffers (a full HD frame
* is, for instance, more then 2 mega pixels large, i.e. more than 6
* MB of memory), which makes mechanisms such as kmalloc() or
* alloc_page() ineffective.
*
* At the same time, a solution where a big memory region is
* reserved for a device is suboptimal since often more memory is
* reserved then strictly required and, moreover, the memory is
* inaccessible to page system even if device drivers don't use it.
*
* CMA tries to solve this issue by operating on memory regions
* where only movable pages can be allocated from. This way, kernel
* can use the memory for pagecache and when device driver requests
* it, allocated pages can be migrated.
*
* Driver usage
*
* CMA should not be used by the device drivers directly. It is
* only a helper framework for dma-mapping subsystem.
*
* For more information, see kernel-docs in drivers/base/dma-contiguous.c
*/
#ifdef __KERNEL__
struct cma;
struct page;
struct device;
#ifdef CONFIG_CMA
struct dma_contiguous_stats {
phys_addr_t base;
size_t size;
};
/*
* There is always at least global CMA area and a few optional device
* private areas configured in kernel .config.
*/
#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS)
extern struct cma *dma_contiguous_default_area;
void dma_contiguous_reserve(phys_addr_t addr_limit);
int dma_declare_contiguous(struct device *dev, phys_addr_t size,
phys_addr_t base, phys_addr_t limit);
struct page *dma_alloc_from_contiguous(struct device *dev, int count,
unsigned int order);
struct page *dma_alloc_at_from_contiguous(struct device *dev, int count,
unsigned int order, phys_addr_t at_addr);
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count);
int dma_get_contiguous_stats(struct device *dev,
struct dma_contiguous_stats *stats);
#else
struct dma_contiguous_stats;
#define MAX_CMA_AREAS (0)
static inline void dma_contiguous_reserve(phys_addr_t limit) { }
static inline
int dma_declare_contiguous(struct device *dev, phys_addr_t size,
phys_addr_t base, phys_addr_t limit)
{
return -ENOSYS;
}
static inline
struct page *dma_alloc_at_from_contiguous(struct device *dev, int count,
unsigned int order, phys_addr_t at_addr)
{
return NULL;
}
static inline
struct page *dma_alloc_from_contiguous(struct device *dev, int count,
unsigned int order)
{
return NULL;
}
static inline
bool dma_release_from_contiguous(struct device *dev, struct page *pages,
int count)
{
return false;
}
static inline
int dma_get_contiguous_stats(struct device *dev,
struct dma_contiguous_stats *stats)
{
return -ENOSYS;
}
#endif
#endif
#endif
|
