linux/drivers/base/dma-buf.c
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   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
  31static inline int is_dma_buf_file(struct file *);
  32
  33static 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
  47static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
  48{
  49        struct dma_buf *dmabuf;
  50
  51        if (!is_dma_buf_file(file))
  52                return -EINVAL;
  53
  54        dmabuf = file->private_data;
  55
  56        /* check for overflowing the buffer's size */
  57        if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
  58            dmabuf->size >> PAGE_SHIFT)
  59                return -EINVAL;
  60
  61        return dmabuf->ops->mmap(dmabuf, vma);
  62}
  63
  64static const struct file_operations dma_buf_fops = {
  65        .release        = dma_buf_release,
  66        .mmap           = dma_buf_mmap_internal,
  67};
  68
  69/*
  70 * is_dma_buf_file - Check if struct file* is associated with dma_buf
  71 */
  72static inline int is_dma_buf_file(struct file *file)
  73{
  74        return file->f_op == &dma_buf_fops;
  75}
  76
  77/**
  78 * dma_buf_export - Creates a new dma_buf, and associates an anon file
  79 * with this buffer, so it can be exported.
  80 * Also connect the allocator specific data and ops to the buffer.
  81 *
  82 * @priv:       [in]    Attach private data of allocator to this buffer
  83 * @ops:        [in]    Attach allocator-defined dma buf ops to the new buffer.
  84 * @size:       [in]    Size of the buffer
  85 * @flags:      [in]    mode flags for the file.
  86 *
  87 * Returns, on success, a newly created dma_buf object, which wraps the
  88 * supplied private data and operations for dma_buf_ops. On either missing
  89 * ops, or error in allocating struct dma_buf, will return negative error.
  90 *
  91 */
  92struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
  93                                size_t size, int flags)
  94{
  95        struct dma_buf *dmabuf;
  96        struct file *file;
  97
  98        if (WARN_ON(!priv || !ops
  99                          || !ops->map_dma_buf
 100                          || !ops->unmap_dma_buf
 101                          || !ops->release
 102                          || !ops->kmap_atomic
 103                          || !ops->kmap
 104                          || !ops->mmap)) {
 105                return ERR_PTR(-EINVAL);
 106        }
 107
 108        dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
 109        if (dmabuf == NULL)
 110                return ERR_PTR(-ENOMEM);
 111
 112        dmabuf->priv = priv;
 113        dmabuf->ops = ops;
 114        dmabuf->size = size;
 115
 116        file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
 117
 118        dmabuf->file = file;
 119
 120        mutex_init(&dmabuf->lock);
 121        INIT_LIST_HEAD(&dmabuf->attachments);
 122
 123        return dmabuf;
 124}
 125EXPORT_SYMBOL_GPL(dma_buf_export);
 126
 127
 128/**
 129 * dma_buf_fd - returns a file descriptor for the given dma_buf
 130 * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
 131 * @flags:      [in]    flags to give to fd
 132 *
 133 * On success, returns an associated 'fd'. Else, returns error.
 134 */
 135int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 136{
 137        int error, fd;
 138
 139        if (!dmabuf || !dmabuf->file)
 140                return -EINVAL;
 141
 142        error = get_unused_fd_flags(flags);
 143        if (error < 0)
 144                return error;
 145        fd = error;
 146
 147        fd_install(fd, dmabuf->file);
 148
 149        return fd;
 150}
 151EXPORT_SYMBOL_GPL(dma_buf_fd);
 152
 153/**
 154 * dma_buf_get - returns the dma_buf structure related to an fd
 155 * @fd: [in]    fd associated with the dma_buf to be returned
 156 *
 157 * On success, returns the dma_buf structure associated with an fd; uses
 158 * file's refcounting done by fget to increase refcount. returns ERR_PTR
 159 * otherwise.
 160 */
 161struct dma_buf *dma_buf_get(int fd)
 162{
 163        struct file *file;
 164
 165        file = fget(fd);
 166
 167        if (!file)
 168                return ERR_PTR(-EBADF);
 169
 170        if (!is_dma_buf_file(file)) {
 171                fput(file);
 172                return ERR_PTR(-EINVAL);
 173        }
 174
 175        return file->private_data;
 176}
 177EXPORT_SYMBOL_GPL(dma_buf_get);
 178
 179/**
 180 * dma_buf_put - decreases refcount of the buffer
 181 * @dmabuf:     [in]    buffer to reduce refcount of
 182 *
 183 * Uses file's refcounting done implicitly by fput()
 184 */
 185void dma_buf_put(struct dma_buf *dmabuf)
 186{
 187        if (WARN_ON(!dmabuf || !dmabuf->file))
 188                return;
 189
 190        fput(dmabuf->file);
 191}
 192EXPORT_SYMBOL_GPL(dma_buf_put);
 193
 194/**
 195 * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 196 * calls attach() of dma_buf_ops to allow device-specific attach functionality
 197 * @dmabuf:     [in]    buffer to attach device to.
 198 * @dev:        [in]    device to be attached.
 199 *
 200 * Returns struct dma_buf_attachment * for this attachment; may return negative
 201 * error codes.
 202 *
 203 */
 204struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 205                                          struct device *dev)
 206{
 207        struct dma_buf_attachment *attach;
 208        int ret;
 209
 210        if (WARN_ON(!dmabuf || !dev))
 211                return ERR_PTR(-EINVAL);
 212
 213        attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 214        if (attach == NULL)
 215                return ERR_PTR(-ENOMEM);
 216
 217        attach->dev = dev;
 218        attach->dmabuf = dmabuf;
 219
 220        mutex_lock(&dmabuf->lock);
 221
 222        if (dmabuf->ops->attach) {
 223                ret = dmabuf->ops->attach(dmabuf, dev, attach);
 224                if (ret)
 225                        goto err_attach;
 226        }
 227        list_add(&attach->node, &dmabuf->attachments);
 228
 229        mutex_unlock(&dmabuf->lock);
 230        return attach;
 231
 232err_attach:
 233        kfree(attach);
 234        mutex_unlock(&dmabuf->lock);
 235        return ERR_PTR(ret);
 236}
 237EXPORT_SYMBOL_GPL(dma_buf_attach);
 238
 239/**
 240 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 241 * optionally calls detach() of dma_buf_ops for device-specific detach
 242 * @dmabuf:     [in]    buffer to detach from.
 243 * @attach:     [in]    attachment to be detached; is free'd after this call.
 244 *
 245 */
 246void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 247{
 248        if (WARN_ON(!dmabuf || !attach))
 249                return;
 250
 251        mutex_lock(&dmabuf->lock);
 252        list_del(&attach->node);
 253        if (dmabuf->ops->detach)
 254                dmabuf->ops->detach(dmabuf, attach);
 255
 256        mutex_unlock(&dmabuf->lock);
 257        kfree(attach);
 258}
 259EXPORT_SYMBOL_GPL(dma_buf_detach);
 260
 261/**
 262 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 263 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 264 * dma_buf_ops.
 265 * @attach:     [in]    attachment whose scatterlist is to be returned
 266 * @direction:  [in]    direction of DMA transfer
 267 *
 268 * Returns sg_table containing the scatterlist to be returned; may return NULL
 269 * or ERR_PTR.
 270 *
 271 */
 272struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 273                                        enum dma_data_direction direction)
 274{
 275        struct sg_table *sg_table = ERR_PTR(-EINVAL);
 276
 277        might_sleep();
 278
 279        if (WARN_ON(!attach || !attach->dmabuf))
 280                return ERR_PTR(-EINVAL);
 281
 282        sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 283
 284        return sg_table;
 285}
 286EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 287
 288/**
 289 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 290 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 291 * dma_buf_ops.
 292 * @attach:     [in]    attachment to unmap buffer from
 293 * @sg_table:   [in]    scatterlist info of the buffer to unmap
 294 * @direction:  [in]    direction of DMA transfer
 295 *
 296 */
 297void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 298                                struct sg_table *sg_table,
 299                                enum dma_data_direction direction)
 300{
 301        might_sleep();
 302
 303        if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
 304                return;
 305
 306        attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
 307                                                direction);
 308}
 309EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
 310
 311
 312/**
 313 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
 314 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
 315 * preparations. Coherency is only guaranteed in the specified range for the
 316 * specified access direction.
 317 * @dmabuf:     [in]    buffer to prepare cpu access for.
 318 * @start:      [in]    start of range for cpu access.
 319 * @len:        [in]    length of range for cpu access.
 320 * @direction:  [in]    length of range for cpu access.
 321 *
 322 * Can return negative error values, returns 0 on success.
 323 */
 324int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
 325                             enum dma_data_direction direction)
 326{
 327        int ret = 0;
 328
 329        if (WARN_ON(!dmabuf))
 330                return -EINVAL;
 331
 332        if (dmabuf->ops->begin_cpu_access)
 333                ret = dmabuf->ops->begin_cpu_access(dmabuf, start, len, direction);
 334
 335        return ret;
 336}
 337EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
 338
 339/**
 340 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
 341 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
 342 * actions. Coherency is only guaranteed in the specified range for the
 343 * specified access direction.
 344 * @dmabuf:     [in]    buffer to complete cpu access for.
 345 * @start:      [in]    start of range for cpu access.
 346 * @len:        [in]    length of range for cpu access.
 347 * @direction:  [in]    length of range for cpu access.
 348 *
 349 * This call must always succeed.
 350 */
 351void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
 352                            enum dma_data_direction direction)
 353{
 354        WARN_ON(!dmabuf);
 355
 356        if (dmabuf->ops->end_cpu_access)
 357                dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
 358}
 359EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 360
 361/**
 362 * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
 363 * space. The same restrictions as for kmap_atomic and friends apply.
 364 * @dmabuf:     [in]    buffer to map page from.
 365 * @page_num:   [in]    page in PAGE_SIZE units to map.
 366 *
 367 * This call must always succeed, any necessary preparations that might fail
 368 * need to be done in begin_cpu_access.
 369 */
 370void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
 371{
 372        WARN_ON(!dmabuf);
 373
 374        return dmabuf->ops->kmap_atomic(dmabuf, page_num);
 375}
 376EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
 377
 378/**
 379 * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
 380 * @dmabuf:     [in]    buffer to unmap page from.
 381 * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 382 * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap_atomic.
 383 *
 384 * This call must always succeed.
 385 */
 386void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
 387                           void *vaddr)
 388{
 389        WARN_ON(!dmabuf);
 390
 391        if (dmabuf->ops->kunmap_atomic)
 392                dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
 393}
 394EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
 395
 396/**
 397 * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
 398 * same restrictions as for kmap and friends apply.
 399 * @dmabuf:     [in]    buffer to map page from.
 400 * @page_num:   [in]    page in PAGE_SIZE units to map.
 401 *
 402 * This call must always succeed, any necessary preparations that might fail
 403 * need to be done in begin_cpu_access.
 404 */
 405void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
 406{
 407        WARN_ON(!dmabuf);
 408
 409        return dmabuf->ops->kmap(dmabuf, page_num);
 410}
 411EXPORT_SYMBOL_GPL(dma_buf_kmap);
 412
 413/**
 414 * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
 415 * @dmabuf:     [in]    buffer to unmap page from.
 416 * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 417 * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap.
 418 *
 419 * This call must always succeed.
 420 */
 421void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
 422                    void *vaddr)
 423{
 424        WARN_ON(!dmabuf);
 425
 426        if (dmabuf->ops->kunmap)
 427                dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
 428}
 429EXPORT_SYMBOL_GPL(dma_buf_kunmap);
 430
 431
 432/**
 433 * dma_buf_mmap - Setup up a userspace mmap with the given vma
 434 * @dmabuf:     [in]    buffer that should back the vma
 435 * @vma:        [in]    vma for the mmap
 436 * @pgoff:      [in]    offset in pages where this mmap should start within the
 437 *                      dma-buf buffer.
 438 *
 439 * This function adjusts the passed in vma so that it points at the file of the
 440 * dma_buf operation. It alsog adjusts the starting pgoff and does bounds
 441 * checking on the size of the vma. Then it calls the exporters mmap function to
 442 * set up the mapping.
 443 *
 444 * Can return negative error values, returns 0 on success.
 445 */
 446int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 447                 unsigned long pgoff)
 448{
 449        if (WARN_ON(!dmabuf || !vma))
 450                return -EINVAL;
 451
 452        /* check for offset overflow */
 453        if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
 454                return -EOVERFLOW;
 455
 456        /* check for overflowing the buffer's size */
 457        if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
 458            dmabuf->size >> PAGE_SHIFT)
 459                return -EINVAL;
 460
 461        /* readjust the vma */
 462        if (vma->vm_file)
 463                fput(vma->vm_file);
 464
 465        vma->vm_file = get_file(dmabuf->file);
 466
 467        vma->vm_pgoff = pgoff;
 468
 469        return dmabuf->ops->mmap(dmabuf, vma);
 470}
 471EXPORT_SYMBOL_GPL(dma_buf_mmap);
 472
 473/**
 474 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
 475 * address space. Same restrictions as for vmap and friends apply.
 476 * @dmabuf:     [in]    buffer to vmap
 477 *
 478 * This call may fail due to lack of virtual mapping address space.
 479 * These calls are optional in drivers. The intended use for them
 480 * is for mapping objects linear in kernel space for high use objects.
 481 * Please attempt to use kmap/kunmap before thinking about these interfaces.
 482 */
 483void *dma_buf_vmap(struct dma_buf *dmabuf)
 484{
 485        if (WARN_ON(!dmabuf))
 486                return NULL;
 487
 488        if (dmabuf->ops->vmap)
 489                return dmabuf->ops->vmap(dmabuf);
 490        return NULL;
 491}
 492EXPORT_SYMBOL_GPL(dma_buf_vmap);
 493
 494/**
 495 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
 496 * @dmabuf:     [in]    buffer to vunmap
 497 * @vaddr:      [in]    vmap to vunmap
 498 */
 499void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 500{
 501        if (WARN_ON(!dmabuf))
 502                return;
 503
 504        if (dmabuf->ops->vunmap)
 505                dmabuf->ops->vunmap(dmabuf, vaddr);
 506}
 507EXPORT_SYMBOL_GPL(dma_buf_vunmap);
 508
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