2 * Header file for dma buffer sharing framework.
4 * Copyright(C) 2011 Linaro Limited. All rights reserved.
5 * Author: Sumit Semwal <sumit.semwal@ti.com>
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.
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.
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
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/>.
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>
35 struct dma_buf_attachment;
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
51 * @release: release this buffer; to be called after the last dma_buf_put.
54 int (*attach)(struct dma_buf *, struct device *,
55 struct dma_buf_attachment *);
57 void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
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.
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 *,
67 enum dma_data_direction);
68 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
69 * if the call would block.
72 /* after final dma_buf_put() */
73 void (*release)(struct dma_buf *);
78 * struct dma_buf - shared buffer object
79 * @size: size of the buffer
80 * @file: file pointer used for sharing buffers across, and for refcounting.
81 * @attachments: list of dma_buf_attachment that denotes all devices attached.
82 * @ops: dma_buf_ops associated with this buffer object.
83 * @priv: exporter specific private data for this buffer object.
88 struct list_head attachments;
89 const struct dma_buf_ops *ops;
90 /* mutex to serialize list manipulation and other ops */
96 * struct dma_buf_attachment - holds device-buffer attachment data
97 * @dmabuf: buffer for this attachment.
98 * @dev: device attached to the buffer.
99 * @node: list of dma_buf_attachment.
100 * @priv: exporter specific attachment data.
102 * This structure holds the attachment information between the dma_buf buffer
103 * and its user device(s). The list contains one attachment struct per device
104 * attached to the buffer.
106 struct dma_buf_attachment {
107 struct dma_buf *dmabuf;
109 struct list_head node;
113 #ifdef CONFIG_DMA_SHARED_BUFFER
114 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
116 void dma_buf_detach(struct dma_buf *dmabuf,
117 struct dma_buf_attachment *dmabuf_attach);
118 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
119 size_t size, int flags);
120 int dma_buf_fd(struct dma_buf *dmabuf);
121 struct dma_buf *dma_buf_get(int fd);
122 void dma_buf_put(struct dma_buf *dmabuf);
124 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
125 enum dma_data_direction);
126 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
127 enum dma_data_direction);
130 static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
133 return ERR_PTR(-ENODEV);
136 static inline void dma_buf_detach(struct dma_buf *dmabuf,
137 struct dma_buf_attachment *dmabuf_attach)
142 static inline struct dma_buf *dma_buf_export(void *priv,
143 const struct dma_buf_ops *ops,
144 size_t size, int flags)
146 return ERR_PTR(-ENODEV);
149 static inline int dma_buf_fd(struct dma_buf *dmabuf)
154 static inline struct dma_buf *dma_buf_get(int fd)
156 return ERR_PTR(-ENODEV);
159 static inline void dma_buf_put(struct dma_buf *dmabuf)
164 static inline struct sg_table *dma_buf_map_attachment(
165 struct dma_buf_attachment *attach, enum dma_data_direction write)
167 return ERR_PTR(-ENODEV);
170 static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
171 struct sg_table *sg, enum dma_data_direction dir)
176 #endif /* CONFIG_DMA_SHARED_BUFFER */
178 #endif /* __DMA_BUF_H__ */