Sumit Semwal | d15bd7e | 2011-12-26 14:53:15 +0530 | [diff] [blame] | 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> |
Sumit Semwal | d15bd7e | 2011-12-26 14:53:15 +0530 | [diff] [blame] | 29 | #include <linux/scatterlist.h> |
| 30 | #include <linux/list.h> |
| 31 | #include <linux/dma-mapping.h> |
| 32 | |
Paul Gortmaker | 313162d | 2012-01-30 11:46:54 -0500 | [diff] [blame^] | 33 | struct device; |
Sumit Semwal | d15bd7e | 2011-12-26 14:53:15 +0530 | [diff] [blame] | 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__ */ |