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 caches.
  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  */
  72 struct 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  */
 117 struct 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, attach/detach and vmap/unmap */
 123         struct mutex lock;
 124         unsigned vmapping_counter;
 125         void *vmap_ptr;
 126         void *priv;
 127 };
 128
 129 /**
 130  * struct dma_buf_attachment - holds device-buffer attachment data
 131  * @dmabuf: buffer for this attachment.
 132  * @dev: device attached to the buffer.
 133  * @node: list of dma_buf_attachment.
 134  * @priv: exporter specific attachment data.
 135  *
 136  * This structure holds the attachment information between the dma_buf buffer
 137  * and its user device(s). The list contains one attachment struct per device
 138  * attached to the buffer.
 139  */
 140 struct dma_buf_attachment {
 141         struct dma_buf *dmabuf;
 142         struct device *dev;
 143         struct list_head node;
 144         void *priv;
 145 };
 146
 147 /**
 148  * get_dma_buf - convenience wrapper for get_file.
 149  * @dmabuf:     [in]    pointer to dma_buf
 150  *
 151  * Increments the reference count on the dma-buf, needed in case of drivers
 152  * that either need to create additional references to the dmabuf on the
 153  * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
 154  * so that subsequent exports don't create a new dmabuf.
 155  */
 156 static inline void get_dma_buf(struct dma_buf *dmabuf)
 157 {
 158         get_file(dmabuf->file);
 159 }
 160
 161 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 162                                                         struct device *dev);
 163 void dma_buf_detach(struct dma_buf *dmabuf,
 164                                 struct dma_buf_attachment *dmabuf_attach);
 165 struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 166                                size_t size, int flags);
 167 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 168 struct dma_buf *dma_buf_get(int fd);
 169 void dma_buf_put(struct dma_buf *dmabuf);
 170
 171 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
 172                                         enum dma_data_direction);
 173 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
 174                                 enum dma_data_direction);
 175 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 176                              enum dma_data_direction dir);
 177 void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 178                             enum dma_data_direction dir);
 179 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 180 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
 181 void *dma_buf_kmap(struct dma_buf *, unsigned long);
 182 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
 183
 184 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 185                  unsigned long);
 186 void *dma_buf_vmap(struct dma_buf *);
 187 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
 188
 189 #endif /* __DMA_BUF_H__ */