drivers/dma-buf/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/fence.h>
  29 #include <linux/anon_inodes.h>
  30 #include <linux/export.h>
  31 #include <linux/debugfs.h>
  32 #include <linux/module.h>
  33 #include <linux/seq_file.h>
  34 #include <linux/poll.h>
  35 #include <linux/reservation.h>
  36
  37 static inline int is_dma_buf_file(struct file *);
  38
  39 struct dma_buf_callback {
  40         struct list_head list;
  41         void (*callback)(void *);
  42         void *data;
  43 };
  44
  45 struct dma_buf_list {
  46         struct list_head head;
  47         struct mutex lock;
  48 };
  49
  50 static struct dma_buf_list db_list;
  51
  52 static int dma_buf_release(struct inode *inode, struct file *file)
  53 {
  54         struct dma_buf *dmabuf;
  55         struct dma_buf_callback *cb, *tmp;
  56
  57         if (!is_dma_buf_file(file))
  58                 return -EINVAL;
  59
  60         dmabuf = file->private_data;
  61
  62         BUG_ON(dmabuf->vmapping_counter);
  63
  64         /*
  65          * Any fences that a dma-buf poll can wait on should be signaled
  66          * before releasing dma-buf. This is the responsibility of each
  67          * driver that uses the reservation objects.
  68          *
  69          * If you hit this BUG() it means someone dropped their ref to the
  70          * dma-buf while still having pending operation to the buffer.
  71          */
  72         BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
  73
  74         list_for_each_entry_safe(cb, tmp, &dmabuf->release_callbacks, list) {
  75                 if (cb->callback)
  76                         cb->callback(cb->data);
  77                 list_del(&cb->list);
  78                 kfree(cb);
  79         }
  80
  81         dmabuf->ops->release(dmabuf);
  82
  83         mutex_lock(&db_list.lock);
  84         list_del(&dmabuf->list_node);
  85         mutex_unlock(&db_list.lock);
  86
  87         if (dmabuf->resv == (struct reservation_object *)&dmabuf[1])
  88                 reservation_object_fini(dmabuf->resv);
  89
  90         module_put(dmabuf->owner);
  91         kfree(dmabuf);
  92         return 0;
  93 }
  94
  95 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
  96 {
  97         struct dma_buf *dmabuf;
  98
  99         if (!is_dma_buf_file(file))
 100                 return -EINVAL;
 101
 102         dmabuf = file->private_data;
 103
 104         /* check for overflowing the buffer's size */
 105         if (vma->vm_pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
 106             dmabuf->size >> PAGE_SHIFT)
 107                 return -EINVAL;
 108
 109         return dmabuf->ops->mmap(dmabuf, vma);
 110 }
 111
 112 static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
 113 {
 114         struct dma_buf *dmabuf;
 115         loff_t base;
 116
 117         if (!is_dma_buf_file(file))
 118                 return -EBADF;
 119
 120         dmabuf = file->private_data;
 121
 122         /* only support discovering the end of the buffer,
 123            but also allow SEEK_SET to maintain the idiomatic
 124            SEEK_END(0), SEEK_CUR(0) pattern */
 125         if (whence == SEEK_END)
 126                 base = dmabuf->size;
 127         else if (whence == SEEK_SET)
 128                 base = 0;
 129         else
 130                 return -EINVAL;
 131
 132         if (offset != 0)
 133                 return -EINVAL;
 134
 135         return base + offset;
 136 }
 137
 138 static void dma_buf_poll_cb(struct fence *fence, struct fence_cb *cb)
 139 {
 140         struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
 141         unsigned long flags;
 142
 143         spin_lock_irqsave(&dcb->poll->lock, flags);
 144         wake_up_locked_poll(dcb->poll, dcb->active);
 145         dcb->active = 0;
 146         spin_unlock_irqrestore(&dcb->poll->lock, flags);
 147 }
 148
 149 static unsigned int dma_buf_poll(struct file *file, poll_table *poll)
 150 {
 151         struct dma_buf *dmabuf;
 152         struct reservation_object *resv;
 153         struct reservation_object_list *fobj;
 154         struct fence *fence_excl;
 155         unsigned long events;
 156         unsigned shared_count, seq;
 157
 158         dmabuf = file->private_data;
 159         if (!dmabuf || !dmabuf->resv)
 160                 return POLLERR;
 161
 162         resv = dmabuf->resv;
 163
 164         poll_wait(file, &dmabuf->poll, poll);
 165
 166         events = poll_requested_events(poll) & (POLLIN | POLLOUT);
 167         if (!events)
 168                 return 0;
 169
 170 retry:
 171         seq = read_seqcount_begin(&resv->seq);
 172         rcu_read_lock();
 173
 174         fobj = rcu_dereference(resv->fence);
 175         if (fobj)
 176                 shared_count = fobj->shared_count;
 177         else
 178                 shared_count = 0;
 179         fence_excl = rcu_dereference(resv->fence_excl);
 180         if (read_seqcount_retry(&resv->seq, seq)) {
 181                 rcu_read_unlock();
 182                 goto retry;
 183         }
 184
 185         if (fence_excl && (!(events & POLLOUT) || shared_count == 0)) {
 186                 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;
 187                 unsigned long pevents = POLLIN;
 188
 189                 if (shared_count == 0)
 190                         pevents |= POLLOUT;
 191
 192                 spin_lock_irq(&dmabuf->poll.lock);
 193                 if (dcb->active) {
 194                         dcb->active |= pevents;
 195                         events &= ~pevents;
 196                 } else
 197                         dcb->active = pevents;
 198                 spin_unlock_irq(&dmabuf->poll.lock);
 199
 200                 if (events & pevents) {
 201                         if (!fence_get_rcu(fence_excl)) {
 202                                 /* force a recheck */
 203                                 events &= ~pevents;
 204                                 dma_buf_poll_cb(NULL, &dcb->cb);
 205                         } else if (!fence_add_callback(fence_excl, &dcb->cb,
 206                                                        dma_buf_poll_cb)) {
 207                                 events &= ~pevents;
 208                                 fence_put(fence_excl);
 209                         } else {
 210                                 /*
 211                                  * No callback queued, wake up any additional
 212                                  * waiters.
 213                                  */
 214                                 fence_put(fence_excl);
 215                                 dma_buf_poll_cb(NULL, &dcb->cb);
 216                         }
 217                 }
 218         }
 219
 220         if ((events & POLLOUT) && shared_count > 0) {
 221                 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared;
 222                 int i;
 223
 224                 /* Only queue a new callback if no event has fired yet */
 225                 spin_lock_irq(&dmabuf->poll.lock);
 226                 if (dcb->active)
 227                         events &= ~POLLOUT;
 228                 else
 229                         dcb->active = POLLOUT;
 230                 spin_unlock_irq(&dmabuf->poll.lock);
 231
 232                 if (!(events & POLLOUT))
 233                         goto out;
 234
 235                 for (i = 0; i < shared_count; ++i) {
 236                         struct fence *fence = rcu_dereference(fobj->shared[i]);
 237
 238                         if (!fence_get_rcu(fence)) {
 239                                 /*
 240                                  * fence refcount dropped to zero, this means
 241                                  * that fobj has been freed
 242                                  *
 243                                  * call dma_buf_poll_cb and force a recheck!
 244                                  */
 245                                 events &= ~POLLOUT;
 246                                 dma_buf_poll_cb(NULL, &dcb->cb);
 247                                 break;
 248                         }
 249                         if (!fence_add_callback(fence, &dcb->cb,
 250                                                 dma_buf_poll_cb)) {
 251                                 fence_put(fence);
 252                                 events &= ~POLLOUT;
 253                                 break;
 254                         }
 255                         fence_put(fence);
 256                 }
 257
 258                 /* No callback queued, wake up any additional waiters. */
 259                 if (i == shared_count)
 260                         dma_buf_poll_cb(NULL, &dcb->cb);
 261         }
 262
 263 out:
 264         rcu_read_unlock();
 265         return events;
 266 }
 267
 268 static const struct file_operations dma_buf_fops = {
 269         .release        = dma_buf_release,
 270         .mmap           = dma_buf_mmap_internal,
 271         .llseek         = dma_buf_llseek,
 272         .poll           = dma_buf_poll,
 273 };
 274
 275 /*
 276  * is_dma_buf_file - Check if struct file* is associated with dma_buf
 277  */
 278 static inline int is_dma_buf_file(struct file *file)
 279 {
 280         return file->f_op == &dma_buf_fops;
 281 }
 282
 283 int dma_buf_set_release_callback(struct dma_buf *dmabuf,
 284                                  void (*callback)(void *), void *data)
 285 {
 286         struct dma_buf_callback *cb;
 287
 288         if (WARN_ON(dma_buf_get_release_callback_data(dmabuf, callback)))
 289                 return -EINVAL;
 290
 291         cb = kzalloc(sizeof(*cb), GFP_KERNEL);
 292         if (!cb)
 293                 return -ENOMEM;
 294         cb->callback = callback;
 295         cb->data = data;
 296         list_add_tail(&cb->list, &dmabuf->release_callbacks);
 297
 298         return 0;
 299 }
 300
 301 void *dma_buf_get_release_callback_data(struct dma_buf *dmabuf,
 302                                         void (*callback)(void *))
 303 {
 304         struct dma_buf_callback *cb, *tmp;
 305
 306         list_for_each_entry_safe(cb, tmp, &dmabuf->release_callbacks, list) {
 307                 if (cb->callback == callback)
 308                         return cb->data;
 309         }
 310
 311         return NULL;
 312 }
 313
 314 /**
 315  * dma_buf_export - Creates a new dma_buf, and associates an anon file
 316  * with this buffer, so it can be exported.
 317  * Also connect the allocator specific data and ops to the buffer.
 318  * Additionally, provide a name string for exporter; useful in debugging.
 319  *
 320  * @exp_info:   [in]    holds all the export related information provided
 321  *                      by the exporter. see struct dma_buf_export_info
 322  *                      for further details.
 323  *
 324  * Returns, on success, a newly created dma_buf object, which wraps the
 325  * supplied private data and operations for dma_buf_ops. On either missing
 326  * ops, or error in allocating struct dma_buf, will return negative error.
 327  *
 328  */
 329 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 330 {
 331         struct dma_buf *dmabuf;
 332         struct reservation_object *resv = exp_info->resv;
 333         struct file *file;
 334         size_t alloc_size = sizeof(struct dma_buf);
 335
 336         if (!exp_info->resv)
 337                 alloc_size += sizeof(struct reservation_object);
 338         else
 339                 /* prevent &dma_buf[1] == dma_buf->resv */
 340                 alloc_size += 1;
 341
 342         if (WARN_ON(!exp_info->priv
 343                           || !exp_info->ops
 344                           || !exp_info->ops->map_dma_buf
 345                           || !exp_info->ops->unmap_dma_buf
 346                           || !exp_info->ops->release
 347                           || !exp_info->ops->kmap_atomic
 348                           || !exp_info->ops->kmap
 349                           || !exp_info->ops->mmap)) {
 350                 return ERR_PTR(-EINVAL);
 351         }
 352
 353         if (!try_module_get(exp_info->owner))
 354                 return ERR_PTR(-ENOENT);
 355
 356         dmabuf = kzalloc(alloc_size, GFP_KERNEL);
 357         if (!dmabuf) {
 358                 module_put(exp_info->owner);
 359                 return ERR_PTR(-ENOMEM);
 360         }
 361
 362         dmabuf->priv = exp_info->priv;
 363         dmabuf->ops = exp_info->ops;
 364         dmabuf->size = exp_info->size;
 365         dmabuf->exp_name = exp_info->exp_name;
 366         dmabuf->owner = exp_info->owner;
 367         init_waitqueue_head(&dmabuf->poll);
 368         dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
 369         dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
 370
 371         if (!resv) {
 372                 resv = (struct reservation_object *)&dmabuf[1];
 373                 reservation_object_init(resv);
 374         }
 375         dmabuf->resv = resv;
 376
 377         file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
 378                                         exp_info->flags);
 379         if (IS_ERR(file)) {
 380                 kfree(dmabuf);
 381                 return ERR_CAST(file);
 382         }
 383
 384         file->f_mode |= FMODE_LSEEK;
 385         dmabuf->file = file;
 386
 387         mutex_init(&dmabuf->lock);
 388         INIT_LIST_HEAD(&dmabuf->attachments);
 389         INIT_LIST_HEAD(&dmabuf->release_callbacks);
 390
 391         mutex_lock(&db_list.lock);
 392         list_add(&dmabuf->list_node, &db_list.head);
 393         mutex_unlock(&db_list.lock);
 394
 395         return dmabuf;
 396 }
 397 EXPORT_SYMBOL_GPL(dma_buf_export);
 398
 399 /**
 400  * dma_buf_fd - returns a file descriptor for the given dma_buf
 401  * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
 402  * @flags:      [in]    flags to give to fd
 403  *
 404  * On success, returns an associated 'fd'. Else, returns error.
 405  */
 406 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 407 {
 408         int fd;
 409
 410         if (!dmabuf || !dmabuf->file)
 411                 return -EINVAL;
 412
 413         fd = get_unused_fd_flags(flags);
 414         if (fd < 0)
 415                 return fd;
 416
 417         fd_install(fd, dmabuf->file);
 418
 419         return fd;
 420 }
 421 EXPORT_SYMBOL_GPL(dma_buf_fd);
 422
 423 /**
 424  * dma_buf_get - returns the dma_buf structure related to an fd
 425  * @fd: [in]    fd associated with the dma_buf to be returned
 426  *
 427  * On success, returns the dma_buf structure associated with an fd; uses
 428  * file's refcounting done by fget to increase refcount. returns ERR_PTR
 429  * otherwise.
 430  */
 431 struct dma_buf *dma_buf_get(int fd)
 432 {
 433         struct file *file;
 434
 435         file = fget(fd);
 436
 437         if (!file)
 438                 return ERR_PTR(-EBADF);
 439
 440         if (!is_dma_buf_file(file)) {
 441                 fput(file);
 442                 return ERR_PTR(-EINVAL);
 443         }
 444
 445         return file->private_data;
 446 }
 447 EXPORT_SYMBOL_GPL(dma_buf_get);
 448
 449 /**
 450  * dma_buf_put - decreases refcount of the buffer
 451  * @dmabuf:     [in]    buffer to reduce refcount of
 452  *
 453  * Uses file's refcounting done implicitly by fput()
 454  */
 455 void dma_buf_put(struct dma_buf *dmabuf)
 456 {
 457         if (WARN_ON(!dmabuf || !dmabuf->file))
 458                 return;
 459
 460         fput(dmabuf->file);
 461 }
 462 EXPORT_SYMBOL_GPL(dma_buf_put);
 463
 464 /**
 465  * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 466  * calls attach() of dma_buf_ops to allow device-specific attach functionality
 467  * @dmabuf:     [in]    buffer to attach device to.
 468  * @dev:        [in]    device to be attached.
 469  *
 470  * Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on
 471  * error.
 472  */
 473 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 474                                           struct device *dev)
 475 {
 476         struct dma_buf_attachment *attach;
 477         int ret;
 478
 479         if (WARN_ON(!dmabuf || !dev))
 480                 return ERR_PTR(-EINVAL);
 481
 482         attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 483         if (attach == NULL)
 484                 return ERR_PTR(-ENOMEM);
 485
 486         attach->dev = dev;
 487         attach->dmabuf = dmabuf;
 488
 489         mutex_lock(&dmabuf->lock);
 490
 491         if (dmabuf->ops->attach) {
 492                 ret = dmabuf->ops->attach(dmabuf, dev, attach);
 493                 if (ret)
 494                         goto err_attach;
 495         }
 496         list_add(&attach->node, &dmabuf->attachments);
 497
 498         mutex_unlock(&dmabuf->lock);
 499         return attach;
 500
 501 err_attach:
 502         kfree(attach);
 503         mutex_unlock(&dmabuf->lock);
 504         return ERR_PTR(ret);
 505 }
 506 EXPORT_SYMBOL_GPL(dma_buf_attach);
 507
 508 /**
 509  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 510  * optionally calls detach() of dma_buf_ops for device-specific detach
 511  * @dmabuf:     [in]    buffer to detach from.
 512  * @attach:     [in]    attachment to be detached; is free'd after this call.
 513  *
 514  */
 515 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 516 {
 517         if (WARN_ON(!dmabuf || !attach))
 518                 return;
 519
 520         mutex_lock(&dmabuf->lock);
 521         list_del(&attach->node);
 522         if (dmabuf->ops->detach)
 523                 dmabuf->ops->detach(dmabuf, attach);
 524
 525         mutex_unlock(&dmabuf->lock);
 526         kfree(attach);
 527 }
 528 EXPORT_SYMBOL_GPL(dma_buf_detach);
 529
 530 /**
 531  * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 532  * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 533  * dma_buf_ops.
 534  * @attach:     [in]    attachment whose scatterlist is to be returned
 535  * @direction:  [in]    direction of DMA transfer
 536  *
 537  * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
 538  * on error.
 539  */
 540 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 541                                         enum dma_data_direction direction)
 542 {
 543         struct sg_table *sg_table = ERR_PTR(-EINVAL);
 544
 545         might_sleep();
 546
 547         if (WARN_ON(!attach || !attach->dmabuf))
 548                 return ERR_PTR(-EINVAL);
 549
 550         sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 551         if (!sg_table)
 552                 sg_table = ERR_PTR(-ENOMEM);
 553
 554         return sg_table;
 555 }
 556 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 557
 558 /**
 559  * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 560  * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 561  * dma_buf_ops.
 562  * @attach:     [in]    attachment to unmap buffer from
 563  * @sg_table:   [in]    scatterlist info of the buffer to unmap
 564  * @direction:  [in]    direction of DMA transfer
 565  *
 566  */
 567 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 568                                 struct sg_table *sg_table,
 569                                 enum dma_data_direction direction)
 570 {
 571         might_sleep();
 572
 573         if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
 574                 return;
 575
 576         attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
 577                                                 direction);
 578 }
 579 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
 580
 581
 582 /**
 583  * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
 584  * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
 585  * preparations. Coherency is only guaranteed in the specified range for the
 586  * specified access direction.
 587  * @dmabuf:     [in]    buffer to prepare cpu access for.
 588  * @start:      [in]    start of range for cpu access.
 589  * @len:        [in]    length of range for cpu access.
 590  * @direction:  [in]    length of range for cpu access.
 591  *
 592  * Can return negative error values, returns 0 on success.
 593  */
 594 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
 595                              enum dma_data_direction direction)
 596 {
 597         int ret = 0;
 598
 599         if (WARN_ON(!dmabuf))
 600                 return -EINVAL;
 601
 602         if (dmabuf->ops->begin_cpu_access)
 603                 ret = dmabuf->ops->begin_cpu_access(dmabuf, start,
 604                                                         len, direction);
 605
 606         return ret;
 607 }
 608 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
 609
 610 /**
 611  * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
 612  * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
 613  * actions. Coherency is only guaranteed in the specified range for the
 614  * specified access direction.
 615  * @dmabuf:     [in]    buffer to complete cpu access for.
 616  * @start:      [in]    start of range for cpu access.
 617  * @len:        [in]    length of range for cpu access.
 618  * @direction:  [in]    length of range for cpu access.
 619  *
 620  * This call must always succeed.
 621  */
 622 void dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start, size_t len,
 623                             enum dma_data_direction direction)
 624 {
 625         WARN_ON(!dmabuf);
 626
 627         if (dmabuf->ops->end_cpu_access)
 628                 dmabuf->ops->end_cpu_access(dmabuf, start, len, direction);
 629 }
 630 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 631
 632 /**
 633  * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
 634  * space. The same restrictions as for kmap_atomic and friends apply.
 635  * @dmabuf:     [in]    buffer to map page from.
 636  * @page_num:   [in]    page in PAGE_SIZE units to map.
 637  *
 638  * This call must always succeed, any necessary preparations that might fail
 639  * need to be done in begin_cpu_access.
 640  */
 641 void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
 642 {
 643         WARN_ON(!dmabuf);
 644
 645         return dmabuf->ops->kmap_atomic(dmabuf, page_num);
 646 }
 647 EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
 648
 649 /**
 650  * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
 651  * @dmabuf:     [in]    buffer to unmap page from.
 652  * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 653  * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap_atomic.
 654  *
 655  * This call must always succeed.
 656  */
 657 void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
 658                            void *vaddr)
 659 {
 660         WARN_ON(!dmabuf);
 661
 662         if (dmabuf->ops->kunmap_atomic)
 663                 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
 664 }
 665 EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
 666
 667 /**
 668  * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
 669  * same restrictions as for kmap and friends apply.
 670  * @dmabuf:     [in]    buffer to map page from.
 671  * @page_num:   [in]    page in PAGE_SIZE units to map.
 672  *
 673  * This call must always succeed, any necessary preparations that might fail
 674  * need to be done in begin_cpu_access.
 675  */
 676 void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
 677 {
 678         WARN_ON(!dmabuf);
 679
 680         return dmabuf->ops->kmap(dmabuf, page_num);
 681 }
 682 EXPORT_SYMBOL_GPL(dma_buf_kmap);
 683
 684 /**
 685  * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
 686  * @dmabuf:     [in]    buffer to unmap page from.
 687  * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 688  * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap.
 689  *
 690  * This call must always succeed.
 691  */
 692 void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
 693                     void *vaddr)
 694 {
 695         WARN_ON(!dmabuf);
 696
 697         if (dmabuf->ops->kunmap)
 698                 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
 699 }
 700 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
 701
 702
 703 /**
 704  * dma_buf_mmap - Setup up a userspace mmap with the given vma
 705  * @dmabuf:     [in]    buffer that should back the vma
 706  * @vma:        [in]    vma for the mmap
 707  * @pgoff:      [in]    offset in pages where this mmap should start within the
 708  *                      dma-buf buffer.
 709  *
 710  * This function adjusts the passed in vma so that it points at the file of the
 711  * dma_buf operation. It also adjusts the starting pgoff and does bounds
 712  * checking on the size of the vma. Then it calls the exporters mmap function to
 713  * set up the mapping.
 714  *
 715  * Can return negative error values, returns 0 on success.
 716  */
 717 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 718                  unsigned long pgoff)
 719 {
 720         struct file *oldfile;
 721         int ret;
 722
 723         if (WARN_ON(!dmabuf || !vma))
 724                 return -EINVAL;
 725
 726         /* check for offset overflow */
 727         if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) < pgoff)
 728                 return -EOVERFLOW;
 729
 730         /* check for overflowing the buffer's size */
 731         if (pgoff + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) >
 732             dmabuf->size >> PAGE_SHIFT)
 733                 return -EINVAL;
 734
 735         /* readjust the vma */
 736         get_file(dmabuf->file);
 737         oldfile = vma->vm_file;
 738         vma->vm_file = dmabuf->file;
 739         vma->vm_pgoff = pgoff;
 740
 741         ret = dmabuf->ops->mmap(dmabuf, vma);
 742         if (ret) {
 743                 /* restore old parameters on failure */
 744                 vma->vm_file = oldfile;
 745                 fput(dmabuf->file);
 746         } else {
 747                 if (oldfile)
 748                         fput(oldfile);
 749         }
 750         return ret;
 751
 752 }
 753 EXPORT_SYMBOL_GPL(dma_buf_mmap);
 754
 755 /**
 756  * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
 757  * address space. Same restrictions as for vmap and friends apply.
 758  * @dmabuf:     [in]    buffer to vmap
 759  *
 760  * This call may fail due to lack of virtual mapping address space.
 761  * These calls are optional in drivers. The intended use for them
 762  * is for mapping objects linear in kernel space for high use objects.
 763  * Please attempt to use kmap/kunmap before thinking about these interfaces.
 764  *
 765  * Returns NULL on error.
 766  */
 767 void *dma_buf_vmap(struct dma_buf *dmabuf)
 768 {
 769         void *ptr;
 770
 771         if (WARN_ON(!dmabuf))
 772                 return NULL;
 773
 774         if (!dmabuf->ops->vmap)
 775                 return NULL;
 776
 777         mutex_lock(&dmabuf->lock);
 778         if (dmabuf->vmapping_counter) {
 779                 dmabuf->vmapping_counter++;
 780                 BUG_ON(!dmabuf->vmap_ptr);
 781                 ptr = dmabuf->vmap_ptr;
 782                 goto out_unlock;
 783         }
 784
 785         BUG_ON(dmabuf->vmap_ptr);
 786
 787         ptr = dmabuf->ops->vmap(dmabuf);
 788         if (WARN_ON_ONCE(IS_ERR(ptr)))
 789                 ptr = NULL;
 790         if (!ptr)
 791                 goto out_unlock;
 792
 793         dmabuf->vmap_ptr = ptr;
 794         dmabuf->vmapping_counter = 1;
 795
 796 out_unlock:
 797         mutex_unlock(&dmabuf->lock);
 798         return ptr;
 799 }
 800 EXPORT_SYMBOL_GPL(dma_buf_vmap);
 801
 802 /**
 803  * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
 804  * @dmabuf:     [in]    buffer to vunmap
 805  * @vaddr:      [in]    vmap to vunmap
 806  */
 807 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 808 {
 809         if (WARN_ON(!dmabuf))
 810                 return;
 811
 812         BUG_ON(!dmabuf->vmap_ptr);
 813         BUG_ON(dmabuf->vmapping_counter == 0);
 814         BUG_ON(dmabuf->vmap_ptr != vaddr);
 815
 816         mutex_lock(&dmabuf->lock);
 817         if (--dmabuf->vmapping_counter == 0) {
 818                 if (dmabuf->ops->vunmap)
 819                         dmabuf->ops->vunmap(dmabuf, vaddr);
 820                 dmabuf->vmap_ptr = NULL;
 821         }
 822         mutex_unlock(&dmabuf->lock);
 823 }
 824 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
 825
 826 #ifdef CONFIG_DEBUG_FS
 827 static int dma_buf_describe(struct seq_file *s)
 828 {
 829         int ret;
 830         struct dma_buf *buf_obj;
 831         struct dma_buf_attachment *attach_obj;
 832         int count = 0, attach_count;
 833         size_t size = 0;
 834
 835         ret = mutex_lock_interruptible(&db_list.lock);
 836
 837         if (ret)
 838                 return ret;
 839
 840         seq_puts(s, "\nDma-buf Objects:\n");
 841         seq_puts(s, "size\tflags\tmode\tcount\texp_name\n");
 842
 843         list_for_each_entry(buf_obj, &db_list.head, list_node) {
 844                 ret = mutex_lock_interruptible(&buf_obj->lock);
 845
 846                 if (ret) {
 847                         seq_puts(s,
 848                                  "\tERROR locking buffer object: skipping\n");
 849                         continue;
 850                 }
 851
 852                 seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\n",
 853                                 buf_obj->size,
 854                                 buf_obj->file->f_flags, buf_obj->file->f_mode,
 855                                 file_count(buf_obj->file),
 856                                 buf_obj->exp_name);
 857
 858                 seq_puts(s, "\tAttached Devices:\n");
 859                 attach_count = 0;
 860
 861                 list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
 862                         seq_puts(s, "\t");
 863
 864                         seq_printf(s, "%s\n", dev_name(attach_obj->dev));
 865                         attach_count++;
 866                 }
 867
 868                 seq_printf(s, "Total %d devices attached\n\n",
 869                                 attach_count);
 870
 871                 count++;
 872                 size += buf_obj->size;
 873                 mutex_unlock(&buf_obj->lock);
 874         }
 875
 876         seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
 877
 878         mutex_unlock(&db_list.lock);
 879         return 0;
 880 }
 881
 882 static int dma_buf_show(struct seq_file *s, void *unused)
 883 {
 884         void (*func)(struct seq_file *) = s->private;
 885
 886         func(s);
 887         return 0;
 888 }
 889
 890 static int dma_buf_debug_open(struct inode *inode, struct file *file)
 891 {
 892         return single_open(file, dma_buf_show, inode->i_private);
 893 }
 894
 895 static const struct file_operations dma_buf_debug_fops = {
 896         .open           = dma_buf_debug_open,
 897         .read           = seq_read,
 898         .llseek         = seq_lseek,
 899         .release        = single_release,
 900 };
 901
 902 static struct dentry *dma_buf_debugfs_dir;
 903
 904 static int dma_buf_init_debugfs(void)
 905 {
 906         int err = 0;
 907
 908         dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL);
 909
 910         if (IS_ERR(dma_buf_debugfs_dir)) {
 911                 err = PTR_ERR(dma_buf_debugfs_dir);
 912                 dma_buf_debugfs_dir = NULL;
 913                 return err;
 914         }
 915
 916         err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe);
 917
 918         if (err)
 919                 pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
 920
 921         return err;
 922 }
 923
 924 static void dma_buf_uninit_debugfs(void)
 925 {
 926         if (dma_buf_debugfs_dir)
 927                 debugfs_remove_recursive(dma_buf_debugfs_dir);
 928 }
 929
 930 int dma_buf_debugfs_create_file(const char *name,
 931                                 int (*write)(struct seq_file *))
 932 {
 933         struct dentry *d;
 934
 935         d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
 936                         write, &dma_buf_debug_fops);
 937
 938         return PTR_ERR_OR_ZERO(d);
 939 }
 940 #else
 941 static inline int dma_buf_init_debugfs(void)
 942 {
 943         return 0;
 944 }
 945 static inline void dma_buf_uninit_debugfs(void)
 946 {
 947 }
 948 #endif
 949
 950 static int __init dma_buf_init(void)
 951 {
 952         mutex_init(&db_list.lock);
 953         INIT_LIST_HEAD(&db_list.head);
 954         dma_buf_init_debugfs();
 955         return 0;
 956 }
 957 subsys_initcall(dma_buf_init);
 958
 959 static void __exit dma_buf_deinit(void)
 960 {
 961         dma_buf_uninit_debugfs();
 962 }
 963 __exitcall(dma_buf_deinit);