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1 | /* |
2 | * Header file for dma buffer sharing framework. | |
3 | * | |
4 | * Copyright(C) 2011 Linaro Limited. All rights reserved. | |
5 | * Author: Sumit Semwal <sumit.semwal@ti.com> | |
6 | * | |
7 | * Many thanks to linaro-mm-sig list, and specially | |
8 | * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and | |
9 | * Daniel Vetter <daniel@ffwll.ch> for their support in creation and | |
10 | * refining of this idea. | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or modify it | |
13 | * under the terms of the GNU General Public License version 2 as published by | |
14 | * the Free Software Foundation. | |
15 | * | |
16 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
18 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
19 | * more details. | |
20 | * | |
21 | * You should have received a copy of the GNU General Public License along with | |
22 | * this program. If not, see <http://www.gnu.org/licenses/>. | |
23 | */ | |
24 | #ifndef __DMA_BUF_H__ | |
25 | #define __DMA_BUF_H__ | |
26 | ||
27 | #include <linux/file.h> | |
28 | #include <linux/err.h> | |
29 | #include <linux/device.h> | |
30 | #include <linux/scatterlist.h> | |
31 | #include <linux/list.h> | |
32 | #include <linux/dma-mapping.h> | |
33 | ||
34 | struct dma_buf; | |
35 | struct dma_buf_attachment; | |
36 | ||
37 | /** | |
38 | * struct dma_buf_ops - operations possible on struct dma_buf | |
39 | * @attach: [optional] allows different devices to 'attach' themselves to the | |
40 | * given buffer. It might return -EBUSY to signal that backing storage | |
41 | * is already allocated and incompatible with the requirements | |
42 | * of requesting device. | |
43 | * @detach: [optional] detach a given device from this buffer. | |
44 | * @map_dma_buf: returns list of scatter pages allocated, increases usecount | |
45 | * of the buffer. Requires atleast one attach to be called | |
46 | * before. Returned sg list should already be mapped into | |
47 | * _device_ address space. This call may sleep. May also return | |
48 | * -EINTR. Should return -EINVAL if attach hasn't been called yet. | |
49 | * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter | |
50 | * pages. | |
51 | * @release: release this buffer; to be called after the last dma_buf_put. | |
52 | */ | |
53 | struct dma_buf_ops { | |
54 | int (*attach)(struct dma_buf *, struct device *, | |
55 | struct dma_buf_attachment *); | |
56 | ||
57 | void (*detach)(struct dma_buf *, struct dma_buf_attachment *); | |
58 | ||
59 | /* For {map,unmap}_dma_buf below, any specific buffer attributes | |
60 | * required should get added to device_dma_parameters accessible | |
61 | * via dev->dma_params. | |
62 | */ | |
63 | struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *, | |
64 | enum dma_data_direction); | |
65 | void (*unmap_dma_buf)(struct dma_buf_attachment *, | |
66 | struct sg_table *); | |
67 | /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY | |
68 | * if the call would block. | |
69 | */ | |
70 | ||
71 | /* after final dma_buf_put() */ | |
72 | void (*release)(struct dma_buf *); | |
73 | ||
74 | }; | |
75 | ||
76 | /** | |
77 | * struct dma_buf - shared buffer object | |
78 | * @size: size of the buffer | |
79 | * @file: file pointer used for sharing buffers across, and for refcounting. | |
80 | * @attachments: list of dma_buf_attachment that denotes all devices attached. | |
81 | * @ops: dma_buf_ops associated with this buffer object. | |
82 | * @priv: exporter specific private data for this buffer object. | |
83 | */ | |
84 | struct dma_buf { | |
85 | size_t size; | |
86 | struct file *file; | |
87 | struct list_head attachments; | |
88 | const struct dma_buf_ops *ops; | |
89 | /* mutex to serialize list manipulation and other ops */ | |
90 | struct mutex lock; | |
91 | void *priv; | |
92 | }; | |
93 | ||
94 | /** | |
95 | * struct dma_buf_attachment - holds device-buffer attachment data | |
96 | * @dmabuf: buffer for this attachment. | |
97 | * @dev: device attached to the buffer. | |
98 | * @node: list of dma_buf_attachment. | |
99 | * @priv: exporter specific attachment data. | |
100 | * | |
101 | * This structure holds the attachment information between the dma_buf buffer | |
102 | * and its user device(s). The list contains one attachment struct per device | |
103 | * attached to the buffer. | |
104 | */ | |
105 | struct dma_buf_attachment { | |
106 | struct dma_buf *dmabuf; | |
107 | struct device *dev; | |
108 | struct list_head node; | |
109 | void *priv; | |
110 | }; | |
111 | ||
112 | #ifdef CONFIG_DMA_SHARED_BUFFER | |
113 | struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, | |
114 | struct device *dev); | |
115 | void dma_buf_detach(struct dma_buf *dmabuf, | |
116 | struct dma_buf_attachment *dmabuf_attach); | |
117 | struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops, | |
118 | size_t size, int flags); | |
119 | int dma_buf_fd(struct dma_buf *dmabuf); | |
120 | struct dma_buf *dma_buf_get(int fd); | |
121 | void dma_buf_put(struct dma_buf *dmabuf); | |
122 | ||
123 | struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, | |
124 | enum dma_data_direction); | |
125 | void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *); | |
126 | #else | |
127 | ||
128 | static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, | |
129 | struct device *dev) | |
130 | { | |
131 | return ERR_PTR(-ENODEV); | |
132 | } | |
133 | ||
134 | static inline void dma_buf_detach(struct dma_buf *dmabuf, | |
135 | struct dma_buf_attachment *dmabuf_attach) | |
136 | { | |
137 | return; | |
138 | } | |
139 | ||
140 | static inline struct dma_buf *dma_buf_export(void *priv, | |
141 | struct dma_buf_ops *ops, | |
142 | size_t size, int flags) | |
143 | { | |
144 | return ERR_PTR(-ENODEV); | |
145 | } | |
146 | ||
147 | static inline int dma_buf_fd(struct dma_buf *dmabuf) | |
148 | { | |
149 | return -ENODEV; | |
150 | } | |
151 | ||
152 | static inline struct dma_buf *dma_buf_get(int fd) | |
153 | { | |
154 | return ERR_PTR(-ENODEV); | |
155 | } | |
156 | ||
157 | static inline void dma_buf_put(struct dma_buf *dmabuf) | |
158 | { | |
159 | return; | |
160 | } | |
161 | ||
162 | static inline struct sg_table *dma_buf_map_attachment( | |
163 | struct dma_buf_attachment *attach, enum dma_data_direction write) | |
164 | { | |
165 | return ERR_PTR(-ENODEV); | |
166 | } | |
167 | ||
168 | static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, | |
169 | struct sg_table *sg) | |
170 | { | |
171 | return; | |
172 | } | |
173 | ||
174 | #endif /* CONFIG_DMA_SHARED_BUFFER */ | |
175 | ||
176 | #endif /* __DMA_BUF_H__ */ |