drivers/base/dma-buf.c

   1 /*
   2  * Framework for buffer objects that can be shared across devices/subsystems.
   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
  25 #include <linux/fs.h>
  26 #include <linux/slab.h>
  27 #include <linux/dma-buf.h>
  28 #include <linux/anon_inodes.h>
  29 #include <linux/export.h>
  30
  31 static inline int is_dma_buf_file(struct file *);
  32
  33 static int dma_buf_release(struct inode *inode, struct file *file)
  34 {
  35         struct dma_buf *dmabuf;
  36
  37         if (!is_dma_buf_file(file))
  38                 return -EINVAL;
  39
  40         dmabuf = file->private_data;
  41
  42         dmabuf->ops->release(dmabuf);
  43         kfree(dmabuf);
  44         return 0;
  45 }
  46
  47 static const struct file_operations dma_buf_fops = {
  48         .release        = dma_buf_release,
  49 };
  50
  51 /*
  52  * is_dma_buf_file - Check if struct file* is associated with dma_buf
  53  */
  54 static inline int is_dma_buf_file(struct file *file)
  55 {
  56         return file->f_op == &dma_buf_fops;
  57 }
  58
  59 /**
  60  * dma_buf_export - Creates a new dma_buf, and associates an anon file
  61  * with this buffer, so it can be exported.
  62  * Also connect the allocator specific data and ops to the buffer.
  63  *
  64  * @priv:       [in]    Attach private data of allocator to this buffer
  65  * @ops:        [in]    Attach allocator-defined dma buf ops to the new buffer.
  66  * @size:       [in]    Size of the buffer
  67  * @flags:      [in]    mode flags for the file.
  68  *
  69  * Returns, on success, a newly created dma_buf object, which wraps the
  70  * supplied private data and operations for dma_buf_ops. On either missing
  71  * ops, or error in allocating struct dma_buf, will return negative error.
  72  *
  73  */
  74 struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
  75                                 size_t size, int flags)
  76 {
  77         struct dma_buf *dmabuf;
  78         struct file *file;
  79
  80         if (WARN_ON(!priv || !ops
  81                           || !ops->map_dma_buf
  82                           || !ops->unmap_dma_buf
  83                           || !ops->release)) {
  84                 return ERR_PTR(-EINVAL);
  85         }
  86
  87         dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
  88         if (dmabuf == NULL)
  89                 return ERR_PTR(-ENOMEM);
  90
  91         dmabuf->priv = priv;
  92         dmabuf->ops = ops;
  93         dmabuf->size = size;
  94
  95         file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
  96
  97         dmabuf->file = file;
  98
  99         mutex_init(&dmabuf->lock);
 100         INIT_LIST_HEAD(&dmabuf->attachments);
 101
 102         return dmabuf;
 103 }
 104 EXPORT_SYMBOL_GPL(dma_buf_export);
 105
 106
 107 /**
 108  * dma_buf_fd - returns a file descriptor for the given dma_buf
 109  * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
 110  *
 111  * On success, returns an associated 'fd'. Else, returns error.
 112  */
 113 int dma_buf_fd(struct dma_buf *dmabuf)
 114 {
 115         int error, fd;
 116
 117         if (!dmabuf || !dmabuf->file)
 118                 return -EINVAL;
 119
 120         error = get_unused_fd();
 121         if (error < 0)
 122                 return error;
 123         fd = error;
 124
 125         fd_install(fd, dmabuf->file);
 126
 127         return fd;
 128 }
 129 EXPORT_SYMBOL_GPL(dma_buf_fd);
 130
 131 /**
 132  * dma_buf_get - returns the dma_buf structure related to an fd
 133  * @fd: [in]    fd associated with the dma_buf to be returned
 134  *
 135  * On success, returns the dma_buf structure associated with an fd; uses
 136  * file's refcounting done by fget to increase refcount. returns ERR_PTR
 137  * otherwise.
 138  */
 139 struct dma_buf *dma_buf_get(int fd)
 140 {
 141         struct file *file;
 142
 143         file = fget(fd);
 144
 145         if (!file)
 146                 return ERR_PTR(-EBADF);
 147
 148         if (!is_dma_buf_file(file)) {
 149                 fput(file);
 150                 return ERR_PTR(-EINVAL);
 151         }
 152
 153         return file->private_data;
 154 }
 155 EXPORT_SYMBOL_GPL(dma_buf_get);
 156
 157 /**
 158  * dma_buf_put - decreases refcount of the buffer
 159  * @dmabuf:     [in]    buffer to reduce refcount of
 160  *
 161  * Uses file's refcounting done implicitly by fput()
 162  */
 163 void dma_buf_put(struct dma_buf *dmabuf)
 164 {
 165         if (WARN_ON(!dmabuf || !dmabuf->file))
 166                 return;
 167
 168         fput(dmabuf->file);
 169 }
 170 EXPORT_SYMBOL_GPL(dma_buf_put);
 171
 172 /**
 173  * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 174  * calls attach() of dma_buf_ops to allow device-specific attach functionality
 175  * @dmabuf:     [in]    buffer to attach device to.
 176  * @dev:        [in]    device to be attached.
 177  *
 178  * Returns struct dma_buf_attachment * for this attachment; may return negative
 179  * error codes.
 180  *
 181  */
 182 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 183                                           struct device *dev)
 184 {
 185         struct dma_buf_attachment *attach;
 186         int ret;
 187
 188         if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
 189                 return ERR_PTR(-EINVAL);
 190
 191         attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 192         if (attach == NULL)
 193                 goto err_alloc;
 194
 195         mutex_lock(&dmabuf->lock);
 196
 197         attach->dev = dev;
 198         attach->dmabuf = dmabuf;
 199         if (dmabuf->ops->attach) {
 200                 ret = dmabuf->ops->attach(dmabuf, dev, attach);
 201                 if (ret)
 202                         goto err_attach;
 203         }
 204         list_add(&attach->node, &dmabuf->attachments);
 205
 206         mutex_unlock(&dmabuf->lock);
 207         return attach;
 208
 209 err_alloc:
 210         return ERR_PTR(-ENOMEM);
 211 err_attach:
 212         kfree(attach);
 213         mutex_unlock(&dmabuf->lock);
 214         return ERR_PTR(ret);
 215 }
 216 EXPORT_SYMBOL_GPL(dma_buf_attach);
 217
 218 /**
 219  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 220  * optionally calls detach() of dma_buf_ops for device-specific detach
 221  * @dmabuf:     [in]    buffer to detach from.
 222  * @attach:     [in]    attachment to be detached; is free'd after this call.
 223  *
 224  */
 225 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 226 {
 227         if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
 228                 return;
 229
 230         mutex_lock(&dmabuf->lock);
 231         list_del(&attach->node);
 232         if (dmabuf->ops->detach)
 233                 dmabuf->ops->detach(dmabuf, attach);
 234
 235         mutex_unlock(&dmabuf->lock);
 236         kfree(attach);
 237 }
 238 EXPORT_SYMBOL_GPL(dma_buf_detach);
 239
 240 /**
 241  * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 242  * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 243  * dma_buf_ops.
 244  * @attach:     [in]    attachment whose scatterlist is to be returned
 245  * @direction:  [in]    direction of DMA transfer
 246  *
 247  * Returns sg_table containing the scatterlist to be returned; may return NULL
 248  * or ERR_PTR.
 249  *
 250  */
 251 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 252                                         enum dma_data_direction direction)
 253 {
 254         struct sg_table *sg_table = ERR_PTR(-EINVAL);
 255
 256         might_sleep();
 257
 258         if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
 259                 return ERR_PTR(-EINVAL);
 260
 261         mutex_lock(&attach->dmabuf->lock);
 262         if (attach->dmabuf->ops->map_dma_buf)
 263                 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 264         mutex_unlock(&attach->dmabuf->lock);
 265
 266         return sg_table;
 267 }
 268 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 269
 270 /**
 271  * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 272  * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 273  * dma_buf_ops.
 274  * @attach:     [in]    attachment to unmap buffer from
 275  * @sg_table:   [in]    scatterlist info of the buffer to unmap
 276  *
 277  */
 278 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 279                                 struct sg_table *sg_table)
 280 {
 281         if (WARN_ON(!attach || !attach->dmabuf || !sg_table
 282                             || !attach->dmabuf->ops))
 283                 return;
 284
 285         mutex_lock(&attach->dmabuf->lock);
 286         if (attach->dmabuf->ops->unmap_dma_buf)
 287                 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
 288         mutex_unlock(&attach->dmabuf->lock);
 289
 290 }
 291 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);