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>
36 struct dma_buf_attachment;
39 * struct dma_buf_ops - operations possible on struct dma_buf
40 * @attach: [optional] allows different devices to 'attach' themselves to the
41 * given buffer. It might return -EBUSY to signal that backing storage
42 * is already allocated and incompatible with the requirements
43 * of requesting device.
44 * @detach: [optional] detach a given device from this buffer.
45 * @map_dma_buf: returns list of scatter pages allocated, increases usecount
46 * of the buffer. Requires atleast one attach to be called
47 * before. Returned sg list should already be mapped into
48 * _device_ address space. This call may sleep. May also return
49 * -EINTR. Should return -EINVAL if attach hasn't been called yet.
50 * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
52 * @release: release this buffer; to be called after the last dma_buf_put.
55 int (*attach)(struct dma_buf *, struct device *,
56 struct dma_buf_attachment *);
58 void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
60 /* For {map,unmap}_dma_buf below, any specific buffer attributes
61 * required should get added to device_dma_parameters accessible
62 * via dev->dma_params.
64 struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
65 enum dma_data_direction);
66 void (*unmap_dma_buf)(struct dma_buf_attachment *,
68 enum dma_data_direction);
69 /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
70 * if the call would block.
73 /* after final dma_buf_put() */
74 void (*release)(struct dma_buf *);
79 * struct dma_buf - shared buffer object
80 * @size: size of the buffer
81 * @file: file pointer used for sharing buffers across, and for refcounting.
82 * @attachments: list of dma_buf_attachment that denotes all devices attached.
83 * @ops: dma_buf_ops associated with this buffer object.
84 * @priv: exporter specific private data for this buffer object.
89 struct list_head attachments;
90 const struct dma_buf_ops *ops;
91 /* mutex to serialize list manipulation and other ops */
97 * struct dma_buf_attachment - holds device-buffer attachment data
98 * @dmabuf: buffer for this attachment.
99 * @dev: device attached to the buffer.
100 * @node: list of dma_buf_attachment.
101 * @priv: exporter specific attachment data.
103 * This structure holds the attachment information between the dma_buf buffer
104 * and its user device(s). The list contains one attachment struct per device
105 * attached to the buffer.
107 struct dma_buf_attachment {
108 struct dma_buf *dmabuf;
110 struct list_head node;
115 * get_dma_buf - convenience wrapper for get_file.
116 * @dmabuf: [in] pointer to dma_buf
118 * Increments the reference count on the dma-buf, needed in case of drivers
119 * that either need to create additional references to the dmabuf on the
120 * kernel side. For example, an exporter that needs to keep a dmabuf ptr
121 * so that subsequent exports don't create a new dmabuf.
123 static inline void get_dma_buf(struct dma_buf *dmabuf)
125 get_file(dmabuf->file);
128 #ifdef CONFIG_DMA_SHARED_BUFFER
129 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
131 void dma_buf_detach(struct dma_buf *dmabuf,
132 struct dma_buf_attachment *dmabuf_attach);
133 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
134 size_t size, int flags);
135 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
136 struct dma_buf *dma_buf_get(int fd);
137 void dma_buf_put(struct dma_buf *dmabuf);
139 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
140 enum dma_data_direction);
141 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
142 enum dma_data_direction);
145 static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
148 return ERR_PTR(-ENODEV);
151 static inline void dma_buf_detach(struct dma_buf *dmabuf,
152 struct dma_buf_attachment *dmabuf_attach)
157 static inline struct dma_buf *dma_buf_export(void *priv,
158 const struct dma_buf_ops *ops,
159 size_t size, int flags)
161 return ERR_PTR(-ENODEV);
164 static inline int dma_buf_fd(struct dma_buf *dmabuf)
169 static inline struct dma_buf *dma_buf_get(int fd)
171 return ERR_PTR(-ENODEV);
174 static inline void dma_buf_put(struct dma_buf *dmabuf)
179 static inline struct sg_table *dma_buf_map_attachment(
180 struct dma_buf_attachment *attach, enum dma_data_direction write)
182 return ERR_PTR(-ENODEV);
185 static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
186 struct sg_table *sg, enum dma_data_direction dir)
191 #endif /* CONFIG_DMA_SHARED_BUFFER */
193 #endif /* __DMA_BUF_H__ */