linux/include/linux/dma-buf.h
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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/scatterlist.h>
  30#include <linux/list.h>
  31#include <linux/dma-mapping.h>
  32#include <linux/fs.h>
  33
  34struct device;
  35struct dma_buf;
  36struct 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 * @mmap: used to expose the backing storage to userspace. Note that the
  65 *        mapping needs to be coherent - if the exporter doesn't directly
  66 *        support this, it needs to fake coherency by shooting down any ptes
  67 *        when transitioning away from the cpu domain.
  68 * @vmap: [optional] creates a virtual mapping for the buffer into kernel
  69 *        address space. Same restrictions as for vmap and friends apply.
  70 * @vunmap: [optional] unmaps a vmap from the buffer
  71 */
  72struct dma_buf_ops {
  73        int (*attach)(struct dma_buf *, struct device *,
  74                        struct dma_buf_attachment *);
  75
  76        void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
  77
  78        /* For {map,unmap}_dma_buf below, any specific buffer attributes
  79         * required should get added to device_dma_parameters accessible
  80         * via dev->dma_params.
  81         */
  82        struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
  83                                                enum dma_data_direction);
  84        void (*unmap_dma_buf)(struct dma_buf_attachment *,
  85                                                struct sg_table *,
  86                                                enum dma_data_direction);
  87        /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
  88         * if the call would block.
  89         */
  90
  91        /* after final dma_buf_put() */
  92        void (*release)(struct dma_buf *);
  93
  94        int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
  95                                enum dma_data_direction);
  96        void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
  97                               enum dma_data_direction);
  98        void *(*kmap_atomic)(struct dma_buf *, unsigned long);
  99        void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
 100        void *(*kmap)(struct dma_buf *, unsigned long);
 101        void (*kunmap)(struct dma_buf *, unsigned long, void *);
 102
 103        int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
 104
 105        void *(*vmap)(struct dma_buf *);
 106        void (*vunmap)(struct dma_buf *, void *vaddr);
 107};
 108
 109/**
 110 * struct dma_buf - shared buffer object
 111 * @size: size of the buffer
 112 * @file: file pointer used for sharing buffers across, and for refcounting.
 113 * @attachments: list of dma_buf_attachment that denotes all devices attached.
 114 * @ops: dma_buf_ops associated with this buffer object.
 115 * @priv: exporter specific private data for this buffer object.
 116 */
 117struct dma_buf {
 118        size_t size;
 119        struct file *file;
 120        struct list_head attachments;
 121        const struct dma_buf_ops *ops;
 122        /* mutex to serialize list manipulation and attach/detach */
 123        struct mutex lock;
 124        void *priv;
 125};
 126
 127/**
 128 * struct dma_buf_attachment - holds device-buffer attachment data
 129 * @dmabuf: buffer for this attachment.
 130 * @dev: device attached to the buffer.
 131 * @node: list of dma_buf_attachment.
 132 * @priv: exporter specific attachment data.
 133 *
 134 * This structure holds the attachment information between the dma_buf buffer
 135 * and its user device(s). The list contains one attachment struct per device
 136 * attached to the buffer.
 137 */
 138struct dma_buf_attachment {
 139        struct dma_buf *dmabuf;
 140        struct device *dev;
 141        struct list_head node;
 142        void *priv;
 143};
 144
 145/**
 146 * get_dma_buf - convenience wrapper for get_file.
 147 * @dmabuf:     [in]    pointer to dma_buf
 148 *
 149 * Increments the reference count on the dma-buf, needed in case of drivers
 150 * that either need to create additional references to the dmabuf on the
 151 * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
 152 * so that subsequent exports don't create a new dmabuf.
 153 */
 154static inline void get_dma_buf(struct dma_buf *dmabuf)
 155{
 156        get_file(dmabuf->file);
 157}
 158
 159#ifdef CONFIG_DMA_SHARED_BUFFER
 160struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 161                                                        struct device *dev);
 162void dma_buf_detach(struct dma_buf *dmabuf,
 163                                struct dma_buf_attachment *dmabuf_attach);
 164struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 165                               size_t size, int flags);
 166int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 167struct dma_buf *dma_buf_get(int fd);
 168void dma_buf_put(struct dma_buf *dmabuf);
 169
 170struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
 171                                        enum dma_data_direction);
 172void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
 173                                enum dma_data_direction);
 174int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 175                             enum dma_data_direction dir);
 176void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 177                            enum dma_data_direction dir);
 178void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 179void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
 180void *dma_buf_kmap(struct dma_buf *, unsigned long);
 181void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
 182
 183int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 184                 unsigned long);
 185void *dma_buf_vmap(struct dma_buf *);
 186void dma_buf_vunmap(struct dma_buf *, void *vaddr);
 187#else
 188
 189static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 190                                                        struct device *dev)
 191{
 192        return ERR_PTR(-ENODEV);
 193}
 194
 195static inline void dma_buf_detach(struct dma_buf *dmabuf,
 196                                  struct dma_buf_attachment *dmabuf_attach)
 197{
 198        return;
 199}
 200
 201static inline struct dma_buf *dma_buf_export(void *priv,
 202                                             const struct dma_buf_ops *ops,
 203                                             size_t size, int flags)
 204{
 205        return ERR_PTR(-ENODEV);
 206}
 207
 208static inline int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 209{
 210        return -ENODEV;
 211}
 212
 213static inline struct dma_buf *dma_buf_get(int fd)
 214{
 215        return ERR_PTR(-ENODEV);
 216}
 217
 218static inline void dma_buf_put(struct dma_buf *dmabuf)
 219{
 220        return;
 221}
 222
 223static inline struct sg_table *dma_buf_map_attachment(
 224        struct dma_buf_attachment *attach, enum dma_data_direction write)
 225{
 226        return ERR_PTR(-ENODEV);
 227}
 228
 229static inline void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 230                        struct sg_table *sg, enum dma_data_direction dir)
 231{
 232        return;
 233}
 234
 235static inline int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 236                                           size_t start, size_t len,
 237                                           enum dma_data_direction dir)
 238{
 239        return -ENODEV;
 240}
 241
 242static inline void dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 243                                          size_t start, size_t len,
 244                                          enum dma_data_direction dir)
 245{
 246}
 247
 248static inline void *dma_buf_kmap_atomic(struct dma_buf *dmabuf,
 249                                        unsigned long pnum)
 250{
 251        return NULL;
 252}
 253
 254static inline void dma_buf_kunmap_atomic(struct dma_buf *dmabuf,
 255                                         unsigned long pnum, void *vaddr)
 256{
 257}
 258
 259static inline void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long pnum)
 260{
 261        return NULL;
 262}
 263
 264static inline void dma_buf_kunmap(struct dma_buf *dmabuf,
 265                                  unsigned long pnum, void *vaddr)
 266{
 267}
 268
 269static inline int dma_buf_mmap(struct dma_buf *dmabuf,
 270                               struct vm_area_struct *vma,
 271                               unsigned long pgoff)
 272{
 273        return -ENODEV;
 274}
 275
 276static inline void *dma_buf_vmap(struct dma_buf *dmabuf)
 277{
 278        return NULL;
 279}
 280
 281static inline void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 282{
 283}
 284#endif /* CONFIG_DMA_SHARED_BUFFER */
 285
 286#endif /* __DMA_BUF_H__ */
 287
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