1#ifndef __LINUX_CMA_H
2#define __LINUX_CMA_H
3
4/*
5 * Contiguous Memory Allocator for DMA mapping framework
6 * Copyright (c) 2010-2011 by Samsung Electronics.
7 * Written by:
8 * Marek Szyprowski <m.szyprowski@samsung.com>
9 * Michal Nazarewicz <mina86@mina86.com>
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 of the
14 * License or (at your optional) any later version of the license.
15 */
16
17/*
18 * Contiguous Memory Allocator
19 *
20 * The Contiguous Memory Allocator (CMA) makes it possible to
21 * allocate big contiguous chunks of memory after the system has
22 * booted.
23 *
24 * Why is it needed?
25 *
26 * Various devices on embedded systems have no scatter-getter and/or
27 * IO map support and require contiguous blocks of memory to
28 * operate. They include devices such as cameras, hardware video
29 * coders, etc.
30 *
31 * Such devices often require big memory buffers (a full HD frame
32 * is, for instance, more then 2 mega pixels large, i.e. more than 6
33 * MB of memory), which makes mechanisms such as kmalloc() or
34 * alloc_page() ineffective.
35 *
36 * At the same time, a solution where a big memory region is
37 * reserved for a device is suboptimal since often more memory is
38 * reserved then strictly required and, moreover, the memory is
39 * inaccessible to page system even if device drivers don't use it.
40 *
41 * CMA tries to solve this issue by operating on memory regions
42 * where only movable pages can be allocated from. This way, kernel
43 * can use the memory for pagecache and when device driver requests
44 * it, allocated pages can be migrated.
45 *
46 * Driver usage
47 *
48 * CMA should not be used by the device drivers directly. It is
49 * only a helper framework for dma-mapping subsystem.
50 *
51 * For more information, see kernel-docs in kernel/dma/contiguous.c
52 */
53
54#ifdef __KERNEL__
55
56#include <linux/device.h>
57
58struct cma;
59struct page;
60
61#ifdef CONFIG_DMA_CMA
62
63extern struct cma *dma_contiguous_default_area;
64
65static inline struct cma *dev_get_cma_area(struct device *dev)
66{
67 if (dev && dev->cma_area)
68 return dev->cma_area;
69 return dma_contiguous_default_area;
70}
71
72static inline void dev_set_cma_area(struct device *dev, struct cma *cma)
73{
74 if (dev)
75 dev->cma_area = cma;
76}
77
78static inline void dma_contiguous_set_default(struct cma *cma)
79{
80 dma_contiguous_default_area = cma;
81}
82
83void dma_contiguous_reserve(phys_addr_t addr_limit);
84
85int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
86 phys_addr_t limit, struct cma **res_cma,
87 bool fixed);
88
89/**
90 * dma_declare_contiguous() - reserve area for contiguous memory handling
91 * for particular device
92 * @dev: Pointer to device structure.
93 * @size: Size of the reserved memory.
94 * @base: Start address of the reserved memory (optional, 0 for any).
95 * @limit: End address of the reserved memory (optional, 0 for any).
96 *
97 * This function reserves memory for specified device. It should be
98 * called by board specific code when early allocator (memblock or bootmem)
99 * is still activate.
100 */
101
102static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size,
103 phys_addr_t base, phys_addr_t limit)
104{
105 struct cma *cma;
106 int ret;
107 ret = dma_contiguous_reserve_area(size, base, limit, &cma, true);
108 if (ret == 0)
109 dev_set_cma_area(dev, cma);
110
111 return ret;
112}
113
114struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
115 unsigned int order, bool no_warn);
116bool dma_release_from_contiguous(struct device *dev, struct page *pages,
117 int count);
118
119#else
120
121static inline struct cma *dev_get_cma_area(struct device *dev)
122{
123 return NULL;
124}
125
126static inline void dev_set_cma_area(struct device *dev, struct cma *cma) { }
127
128static inline void dma_contiguous_set_default(struct cma *cma) { }
129
130static inline void dma_contiguous_reserve(phys_addr_t limit) { }
131
132static inline int dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
133 phys_addr_t limit, struct cma **res_cma,
134 bool fixed)
135{
136 return -ENOSYS;
137}
138
139static inline
140int dma_declare_contiguous(struct device *dev, phys_addr_t size,
141 phys_addr_t base, phys_addr_t limit)
142{
143 return -ENOSYS;
144}
145
146static inline
147struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
148 unsigned int order, bool no_warn)
149{
150 return NULL;
151}
152
153static inline
154bool dma_release_from_contiguous(struct device *dev, struct page *pages,
155 int count)
156{
157 return false;
158}
159
160#endif
161
162#endif
163
164#endif
165