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 #include <linux/fence.h>
  34 #include <linux/wait.h>
  35
  36 struct device;
  37 struct dma_buf;
  38 struct dma_buf_attachment;
  39
  40 /**
  41  * struct dma_buf_ops - operations possible on struct dma_buf
  42  * @attach: [optional] allows different devices to 'attach' themselves to the
  43  *          given buffer. It might return -EBUSY to signal that backing storage
  44  *          is already allocated and incompatible with the requirements
  45  *          of requesting device.
  46  * @detach: [optional] detach a given device from this buffer.
  47  * @map_dma_buf: returns list of scatter pages allocated, increases usecount
  48  *               of the buffer. Requires atleast one attach to be called
  49  *               before. Returned sg list should already be mapped into
  50  *               _device_ address space. This call may sleep. May also return
  51  *               -EINTR. Should return -EINVAL if attach hasn't been called yet.
  52  * @unmap_dma_buf: decreases usecount of buffer, might deallocate scatter
  53  *                 pages.
  54  * @release: release this buffer; to be called after the last dma_buf_put.
  55  * @begin_cpu_access: [optional] called before cpu access to invalidate cpu
  56  *                    caches and allocate backing storage (if not yet done)
  57  *                    respectively pin the objet into memory.
  58  * @end_cpu_access: [optional] called after cpu access to flush caches.
  59  * @kmap_atomic: maps a page from the buffer into kernel address
  60  *               space, users may not block until the subsequent unmap call.
  61  *               This callback must not sleep.
  62  * @kunmap_atomic: [optional] unmaps a atomically mapped page from the buffer.
  63  *                 This Callback must not sleep.
  64  * @kmap: maps a page from the buffer into kernel address space.
  65  * @kunmap: [optional] unmaps a page from the buffer.
  66  * @mmap: used to expose the backing storage to userspace. Note that the
  67  *        mapping needs to be coherent - if the exporter doesn't directly
  68  *        support this, it needs to fake coherency by shooting down any ptes
  69  *        when transitioning away from the cpu domain.
  70  * @vmap: [optional] creates a virtual mapping for the buffer into kernel
  71  *        address space. Same restrictions as for vmap and friends apply.
  72  * @vunmap: [optional] unmaps a vmap from the buffer
  73  */
  74 struct dma_buf_ops {
  75         int (*attach)(struct dma_buf *, struct device *,
  76                         struct dma_buf_attachment *);
  77
  78         void (*detach)(struct dma_buf *, struct dma_buf_attachment *);
  79
  80         /* For {map,unmap}_dma_buf below, any specific buffer attributes
  81          * required should get added to device_dma_parameters accessible
  82          * via dev->dma_params.
  83          */
  84         struct sg_table * (*map_dma_buf)(struct dma_buf_attachment *,
  85                                                 enum dma_data_direction);
  86         void (*unmap_dma_buf)(struct dma_buf_attachment *,
  87                                                 struct sg_table *,
  88                                                 enum dma_data_direction);
  89         /* TODO: Add try_map_dma_buf version, to return immed with -EBUSY
  90          * if the call would block.
  91          */
  92
  93         /* after final dma_buf_put() */
  94         void (*release)(struct dma_buf *);
  95
  96         int (*begin_cpu_access)(struct dma_buf *, size_t, size_t,
  97                                 enum dma_data_direction);
  98         void (*end_cpu_access)(struct dma_buf *, size_t, size_t,
  99                                enum dma_data_direction);
 100         void *(*kmap_atomic)(struct dma_buf *, unsigned long);
 101         void (*kunmap_atomic)(struct dma_buf *, unsigned long, void *);
 102         void *(*kmap)(struct dma_buf *, unsigned long);
 103         void (*kunmap)(struct dma_buf *, unsigned long, void *);
 104
 105         int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);
 106
 107         void *(*vmap)(struct dma_buf *);
 108         void (*vunmap)(struct dma_buf *, void *vaddr);
 109 };
 110
 111 /**
 112  * struct dma_buf - shared buffer object
 113  * @size: size of the buffer
 114  * @file: file pointer used for sharing buffers across, and for refcounting.
 115  * @attachments: list of dma_buf_attachment that denotes all devices attached.
 116  * @ops: dma_buf_ops associated with this buffer object.
 117  * @exp_name: name of the exporter; useful for debugging.
 118  * @owner: pointer to exporter module; used for refcounting when exporter is a
 119  *         kernel module.
 120  * @list_node: node for dma_buf accounting and debugging.
 121  * @priv: exporter specific private data for this buffer object.
 122  * @resv: reservation object linked to this dma-buf
 123  */
 124 struct dma_buf {
 125         size_t size;
 126         struct file *file;
 127         struct list_head attachments;
 128         const struct dma_buf_ops *ops;
 129         /* mutex to serialize list manipulation, attach/detach and vmap/unmap */
 130         struct mutex lock;
 131         unsigned vmapping_counter;
 132         void *vmap_ptr;
 133         const char *exp_name;
 134         struct module *owner;
 135         struct list_head list_node;
 136         void *priv;
 137         struct reservation_object *resv;
 138
 139         /* poll support */
 140         wait_queue_head_t poll;
 141
 142         struct dma_buf_poll_cb_t {
 143                 struct fence_cb cb;
 144                 wait_queue_head_t *poll;
 145
 146                 unsigned long active;
 147         } cb_excl, cb_shared;
 148 };
 149
 150 /**
 151  * struct dma_buf_attachment - holds device-buffer attachment data
 152  * @dmabuf: buffer for this attachment.
 153  * @dev: device attached to the buffer.
 154  * @node: list of dma_buf_attachment.
 155  * @priv: exporter specific attachment data.
 156  *
 157  * This structure holds the attachment information between the dma_buf buffer
 158  * and its user device(s). The list contains one attachment struct per device
 159  * attached to the buffer.
 160  */
 161 struct dma_buf_attachment {
 162         struct dma_buf *dmabuf;
 163         struct device *dev;
 164         struct list_head node;
 165         void *priv;
 166 };
 167
 168 /**
 169  * struct dma_buf_export_info - holds information needed to export a dma_buf
 170  * @exp_name:   name of the exporter - useful for debugging.
 171  * @owner:      pointer to exporter module - used for refcounting kernel module
 172  * @ops:        Attach allocator-defined dma buf ops to the new buffer
 173  * @size:       Size of the buffer
 174  * @flags:      mode flags for the file
 175  * @resv:       reservation-object, NULL to allocate default one
 176  * @priv:       Attach private data of allocator to this buffer
 177  *
 178  * This structure holds the information required to export the buffer. Used
 179  * with dma_buf_export() only.
 180  */
 181 struct dma_buf_export_info {
 182         const char *exp_name;
 183         struct module *owner;
 184         const struct dma_buf_ops *ops;
 185         size_t size;
 186         int flags;
 187         struct reservation_object *resv;
 188         void *priv;
 189 };
 190
 191 /**
 192  * helper macro for exporters; zeros and fills in most common values
 193  */
 194 #define DEFINE_DMA_BUF_EXPORT_INFO(a)   \
 195         struct dma_buf_export_info a = { .exp_name = KBUILD_MODNAME, \
 196                                          .owner = THIS_MODULE }
 197
 198 /**
 199  * get_dma_buf - convenience wrapper for get_file.
 200  * @dmabuf:     [in]    pointer to dma_buf
 201  *
 202  * Increments the reference count on the dma-buf, needed in case of drivers
 203  * that either need to create additional references to the dmabuf on the
 204  * kernel side.  For example, an exporter that needs to keep a dmabuf ptr
 205  * so that subsequent exports don't create a new dmabuf.
 206  */
 207 static inline void get_dma_buf(struct dma_buf *dmabuf)
 208 {
 209         get_file(dmabuf->file);
 210 }
 211
 212 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 213                                                         struct device *dev);
 214 void dma_buf_detach(struct dma_buf *dmabuf,
 215                                 struct dma_buf_attachment *dmabuf_attach);
 216
 217 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info);
 218
 219 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 220 struct dma_buf *dma_buf_get(int fd);
 221 void dma_buf_put(struct dma_buf *dmabuf);
 222
 223 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *,
 224                                         enum dma_data_direction);
 225 void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *,
 226                                 enum dma_data_direction);
 227 int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 228                              enum dma_data_direction dir);
 229 void dma_buf_end_cpu_access(struct dma_buf *dma_buf, size_t start, size_t len,
 230                             enum dma_data_direction dir);
 231 void *dma_buf_kmap_atomic(struct dma_buf *, unsigned long);
 232 void dma_buf_kunmap_atomic(struct dma_buf *, unsigned long, void *);
 233 void *dma_buf_kmap(struct dma_buf *, unsigned long);
 234 void dma_buf_kunmap(struct dma_buf *, unsigned long, void *);
 235
 236 int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 237                  unsigned long);
 238 void *dma_buf_vmap(struct dma_buf *);
 239 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
 240 int dma_buf_debugfs_create_file(const char *name,
 241                                 int (*write)(struct seq_file *));
 242 #endif /* __DMA_BUF_H__ */