include/linux/dma-buf.h

   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/scatterlist.h>
  30 #include <linux/list.h>
  31 #include <linux/dma-mapping.h>
  32 #include <linux/fs.h>
  33
  34 struct device;
  35 struct dma_buf;
  36 struct dma_buf_attachment;
  37
  38 /**
  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
  51  *                 pages.
  52  * @release: release this buffer; to be called after the last dma_buf_put.
  53  * @begin_cpu_access: [optional] called before cpu access to invalidate cpu
  54  *                    caches and allocate backing storage (if not yet done)
  55  *                    respectively pin the objet into memory.
  56  * @end_cpu_access: [optional] called after cpu access to flush cashes.
  57  * @kmap_atomic: maps a page from the buffer into kernel address
  58  *               space, users may not block until the subsequent unmap call.
  59  *               This callback must not sleep.
  60  * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
  61  *                 This Callback must not sleep.
  62  * @kmap: maps a page from the buffer into kernel address space.
  63  * @kunmap: [optional] unmaps a page from the buffer.
  64  */
  65 struct dma_buf_ops {
  66         int (*attach)(struct dma_buf *, struct device *,
  67                         struct dma_buf_attachment *);
  68
  69         void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
  70
  71         /* For {map,unmap}_dma_buf below, any specific buffer attributes
  72          * required should get added to device_dma_parameters accessible
  73          * via dev->dma_params.
  74          */
  75         struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
  76                                                 enum dma_data_direction);
  77         void (*unmap_dma_buf)(struct dma_buf_attachment *,
  78                                                 struct sg_table *,
  79                                                 enum dma_data_direction);
  80         /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
  81          * if the call would block.
  82          */
  83
  84         /* after final dma_buf_put() */
  85         void (*release)(struct dma_buf *);
  86
  87         int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
  88                                 enum dma_data_direction);
  89         void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
  90                                enum dma_data_direction);
  91         void *(*kmap_atomic)(struct dma_buf *, unsigned long);
  92         void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
  93         void *(*kmap)(struct dma_buf *, unsigned long);
  94         void (*kunmap)(struct dma_buf *, unsigned long, void *);
  95 };
  96
  97 /**
  98  * struct dma_buf - shared buffer object
  99  * @size: size of the buffer
 100  * @file: file pointer used for sharing buffers across, and for refcounting.
 101  * @attachments: list of dma_buf_attachment that denotes all devices attached.
 102  * @ops: dma_buf_ops associated with this buffer object.
 103  * @priv: exporter specific private data for this buffer object.
 104  */
 105 struct dma_buf {
 106         size_t size;
 107         struct file *file;
 108         struct list_head attachments;
 109         const struct dma_buf_ops *ops;
 110         /* mutex to serialize list manipulation and attach/detach */
 111         struct mutex lock;
 112         void *priv;
 113 };
 114
 115 /**
 116  * struct dma_buf_attachment - holds device-buffer attachment data
 117  * @dmabuf: buffer for this attachment.
 118  * @dev: device attached to the buffer.
 119  * @node: list of dma_buf_attachment.
 120  * @priv: exporter specific attachment data.
 121  *
 122  * This structure holds the attachment information between the dma_buf buffer
 123  * and its user device(s). The list contains one attachment struct per device
 124  * attached to the buffer.
 125  */
 126 struct dma_buf_attachment {
 127         struct dma_buf *dmabuf;
 128         struct device *dev;
 129         struct list_head node;
 130         void *priv;
 131 };
 132
 133 /**
 134  * get_dma_buf - convenience wrapper for get_file.
 135  * @dmabuf:     [in]    pointer to dma_buf
 136  *
 137  * Increments the reference count on the dma-buf, needed in case of drivers
 138  * that either need to create additional references to the dmabuf on the
 139  * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
 140  * so that subsequent exports don't create a new dmabuf.
 141  */
 142 static inline void get_dma_buf(struct dma_buf *dmabuf)
 143 {
 144         get_file(dmabuf->file);
 145 }
 146
 147 #ifdef CONFIG_DMA_SHARED_BUFFER
 148 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 149                                                         struct device *dev);
 150 void dma_buf_detach(struct dma_buf *dmabuf,
 151                                 struct dma_buf_attachment *dmabuf_attach);
 152 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 153                                size_t size, int flags);
 154 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 155 struct dma_buf *dma_buf_get(int fd);
 156 void dma_buf_put(struct dma_buf *dmabuf);
 157
 158 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
 159                                         enum dma_data_direction);
 160 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
 161                                 enum dma_data_direction);
 162 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 163                              enum dma_data_direction dir);
 164 void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 165                             enum dma_data_direction dir);
 166 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 167 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
 168 void *dma_buf_kmap(struct dma_buf *, unsigned long);
 169 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
 170 #else
 171
 172 static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 173                                                         struct device *dev)
 174 {
 175         return ERR_PTR(-ENODEV);
 176 }
 177
 178 static inline void dma_buf_detach(struct dma_buf *dmabuf,
 179                                   struct dma_buf_attachment *dmabuf_attach)
 180 {
 181         return;
 182 }
 183
 184 static inline struct dma_buf *dma_buf_export(void *priv,
 185                                              const struct dma_buf_ops *ops,
 186                                              size_t size, int flags)
 187 {
 188         return ERR_PTR(-ENODEV);
 189 }
 190
 191 static inline int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 192 {
 193         return -ENODEV;
 194 }
 195
 196 static inline struct dma_buf *dma_buf_get(int fd)
 197 {
 198         return ERR_PTR(-ENODEV);
 199 }
 200
 201 static inline void dma_buf_put(struct dma_buf *dmabuf)
 202 {
 203         return;
 204 }
 205
 206 static inline struct sg_table *dma_buf_map_attachment(
 207         struct dma_buf_attachment *attach, enum dma_data_direction write)
 208 {
 209         return ERR_PTR(-ENODEV);
 210 }
 211
 212 static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 213                         struct sg_table *sg, enum dma_data_direction dir)
 214 {
 215         return;
 216 }
 217
 218 static inline int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 219                                            size_t start, size_t len,
 220                                            enum dma_data_direction dir)
 221 {
 222         return -ENODEV;
 223 }
 224
 225 static inline void dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 226                                           size_t start, size_t len,
 227                                           enum dma_data_direction dir)
 228 {
 229 }
 230
 231 static inline void *dma_buf_kmap_atomic(struct dma_buf *dmabuf,
 232                                         unsigned long pnum)
 233 {
 234         return NULL;
 235 }
 236
 237 static inline void dma_buf_kunmap_atomic(struct dma_buf *dmabuf,
 238                                          unsigned long pnum, void *vaddr)
 239 {
 240 }
 241
 242 static inline void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long pnum)
 243 {
 244         return NULL;
 245 }
 246
 247 static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
 248                                   unsigned long pnum, void *vaddr)
 249 {
 250 }
 251 #endif /* CONFIG_DMA_SHARED_BUFFER */
 252
 253 #endif /* __DMA_BUF_H__ */