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 <[email protected]>
   6  *
   7  * Many thanks to linaro-mm-sig list, and specially
   8  * Arnd Bergmann <[email protected]>, Rob Clark <[email protected]> and
   9  * Daniel Vetter <[email protected]> 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 #include <linux/mm.h>
  37
  38 #include <uapi/linux/dma-buf.h>
  39
  40 static inline int is_dma_buf_file(struct file *);
  41
  42 struct dma_buf_list {
  43         struct list_head head;
  44         struct mutex lock;
  45 };
  46
  47 static struct dma_buf_list db_list;
  48
  49 static int dma_buf_release(struct inode *inode, struct file *file)
  50 {
  51         struct dma_buf *dmabuf;
  52
  53         if (!is_dma_buf_file(file))
  54                 return -EINVAL;
  55
  56         dmabuf = file->private_data;
  57
  58         BUG_ON(dmabuf->vmapping_counter);
  59
  60         /*
  61          * Any fences that a dma-buf poll can wait on should be signaled
  62          * before releasing dma-buf. This is the responsibility of each
  63          * driver that uses the reservation objects.
  64          *
  65          * If you hit this BUG() it means someone dropped their ref to the
  66          * dma-buf while still having pending operation to the buffer.
  67          */
  68         BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);
  69
  70         dmabuf->ops->release(dmabuf);
  71
  72         mutex_lock(&db_list.lock);
  73         list_del(&dmabuf->list_node);
  74         mutex_unlock(&db_list.lock);
  75
  76         if (dmabuf->resv == (struct reservation_object *)&dmabuf[1])
  77                 reservation_object_fini(dmabuf->resv);
  78
  79         module_put(dmabuf->owner);
  80         kfree(dmabuf);
  81         return 0;
  82 }
  83
  84 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
  85 {
  86         struct dma_buf *dmabuf;
  87
  88         if (!is_dma_buf_file(file))
  89                 return -EINVAL;
  90
  91         dmabuf = file->private_data;
  92
  93         /* check for overflowing the buffer's size */
  94         if (vma->vm_pgoff + vma_pages(vma) >
  95             dmabuf->size >> PAGE_SHIFT)
  96                 return -EINVAL;
  97
  98         return dmabuf->ops->mmap(dmabuf, vma);
  99 }
 100
 101 static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
 102 {
 103         struct dma_buf *dmabuf;
 104         loff_t base;
 105
 106         if (!is_dma_buf_file(file))
 107                 return -EBADF;
 108
 109         dmabuf = file->private_data;
 110
 111         /* only support discovering the end of the buffer,
 112            but also allow SEEK_SET to maintain the idiomatic
 113            SEEK_END(0), SEEK_CUR(0) pattern */
 114         if (whence == SEEK_END)
 115                 base = dmabuf->size;
 116         else if (whence == SEEK_SET)
 117                 base = 0;
 118         else
 119                 return -EINVAL;
 120
 121         if (offset != 0)
 122                 return -EINVAL;
 123
 124         return base + offset;
 125 }
 126
 127 static void dma_buf_poll_cb(struct fence *fence, struct fence_cb *cb)
 128 {
 129         struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
 130         unsigned long flags;
 131
 132         spin_lock_irqsave(&dcb->poll->lock, flags);
 133         wake_up_locked_poll(dcb->poll, dcb->active);
 134         dcb->active = 0;
 135         spin_unlock_irqrestore(&dcb->poll->lock, flags);
 136 }
 137
 138 static unsigned int dma_buf_poll(struct file *file, poll_table *poll)
 139 {
 140         struct dma_buf *dmabuf;
 141         struct reservation_object *resv;
 142         struct reservation_object_list *fobj;
 143         struct fence *fence_excl;
 144         unsigned long events;
 145         unsigned shared_count, seq;
 146
 147         dmabuf = file->private_data;
 148         if (!dmabuf || !dmabuf->resv)
 149                 return POLLERR;
 150
 151         resv = dmabuf->resv;
 152
 153         poll_wait(file, &dmabuf->poll, poll);
 154
 155         events = poll_requested_events(poll) & (POLLIN | POLLOUT);
 156         if (!events)
 157                 return 0;
 158
 159 retry:
 160         seq = read_seqcount_begin(&resv->seq);
 161         rcu_read_lock();
 162
 163         fobj = rcu_dereference(resv->fence);
 164         if (fobj)
 165                 shared_count = fobj->shared_count;
 166         else
 167                 shared_count = 0;
 168         fence_excl = rcu_dereference(resv->fence_excl);
 169         if (read_seqcount_retry(&resv->seq, seq)) {
 170                 rcu_read_unlock();
 171                 goto retry;
 172         }
 173
 174         if (fence_excl && (!(events & POLLOUT) || shared_count == 0)) {
 175                 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl;
 176                 unsigned long pevents = POLLIN;
 177
 178                 if (shared_count == 0)
 179                         pevents |= POLLOUT;
 180
 181                 spin_lock_irq(&dmabuf->poll.lock);
 182                 if (dcb->active) {
 183                         dcb->active |= pevents;
 184                         events &= ~pevents;
 185                 } else
 186                         dcb->active = pevents;
 187                 spin_unlock_irq(&dmabuf->poll.lock);
 188
 189                 if (events & pevents) {
 190                         if (!fence_get_rcu(fence_excl)) {
 191                                 /* force a recheck */
 192                                 events &= ~pevents;
 193                                 dma_buf_poll_cb(NULL, &dcb->cb);
 194                         } else if (!fence_add_callback(fence_excl, &dcb->cb,
 195                                                        dma_buf_poll_cb)) {
 196                                 events &= ~pevents;
 197                                 fence_put(fence_excl);
 198                         } else {
 199                                 /*
 200                                  * No callback queued, wake up any additional
 201                                  * waiters.
 202                                  */
 203                                 fence_put(fence_excl);
 204                                 dma_buf_poll_cb(NULL, &dcb->cb);
 205                         }
 206                 }
 207         }
 208
 209         if ((events & POLLOUT) && shared_count > 0) {
 210                 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared;
 211                 int i;
 212
 213                 /* Only queue a new callback if no event has fired yet */
 214                 spin_lock_irq(&dmabuf->poll.lock);
 215                 if (dcb->active)
 216                         events &= ~POLLOUT;
 217                 else
 218                         dcb->active = POLLOUT;
 219                 spin_unlock_irq(&dmabuf->poll.lock);
 220
 221                 if (!(events & POLLOUT))
 222                         goto out;
 223
 224                 for (i = 0; i < shared_count; ++i) {
 225                         struct fence *fence = rcu_dereference(fobj->shared[i]);
 226
 227                         if (!fence_get_rcu(fence)) {
 228                                 /*
 229                                  * fence refcount dropped to zero, this means
 230                                  * that fobj has been freed
 231                                  *
 232                                  * call dma_buf_poll_cb and force a recheck!
 233                                  */
 234                                 events &= ~POLLOUT;
 235                                 dma_buf_poll_cb(NULL, &dcb->cb);
 236                                 break;
 237                         }
 238                         if (!fence_add_callback(fence, &dcb->cb,
 239                                                 dma_buf_poll_cb)) {
 240                                 fence_put(fence);
 241                                 events &= ~POLLOUT;
 242                                 break;
 243                         }
 244                         fence_put(fence);
 245                 }
 246
 247                 /* No callback queued, wake up any additional waiters. */
 248                 if (i == shared_count)
 249                         dma_buf_poll_cb(NULL, &dcb->cb);
 250         }
 251
 252 out:
 253         rcu_read_unlock();
 254         return events;
 255 }
 256
 257 static long dma_buf_ioctl(struct file *file,
 258                           unsigned int cmd, unsigned long arg)
 259 {
 260         struct dma_buf *dmabuf;
 261         struct dma_buf_sync sync;
 262         enum dma_data_direction direction;
 263         int ret;
 264
 265         dmabuf = file->private_data;
 266
 267         switch (cmd) {
 268         case DMA_BUF_IOCTL_SYNC:
 269                 if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
 270                         return -EFAULT;
 271
 272                 if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
 273                         return -EINVAL;
 274
 275                 switch (sync.flags & DMA_BUF_SYNC_RW) {
 276                 case DMA_BUF_SYNC_READ:
 277                         direction = DMA_FROM_DEVICE;
 278                         break;
 279                 case DMA_BUF_SYNC_WRITE:
 280                         direction = DMA_TO_DEVICE;
 281                         break;
 282                 case DMA_BUF_SYNC_RW:
 283                         direction = DMA_BIDIRECTIONAL;
 284                         break;
 285                 default:
 286                         return -EINVAL;
 287                 }
 288
 289                 if (sync.flags & DMA_BUF_SYNC_END)
 290                         ret = dma_buf_end_cpu_access(dmabuf, direction);
 291                 else
 292                         ret = dma_buf_begin_cpu_access(dmabuf, direction);
 293
 294                 return ret;
 295         default:
 296                 return -ENOTTY;
 297         }
 298 }
 299
 300 static const struct file_operations dma_buf_fops = {
 301         .release        = dma_buf_release,
 302         .mmap           = dma_buf_mmap_internal,
 303         .llseek         = dma_buf_llseek,
 304         .poll           = dma_buf_poll,
 305         .unlocked_ioctl = dma_buf_ioctl,
 306 };
 307
 308 /*
 309  * is_dma_buf_file - Check if struct file* is associated with dma_buf
 310  */
 311 static inline int is_dma_buf_file(struct file *file)
 312 {
 313         return file->f_op == &dma_buf_fops;
 314 }
 315
 316 /**
 317  * dma_buf_export - Creates a new dma_buf, and associates an anon file
 318  * with this buffer, so it can be exported.
 319  * Also connect the allocator specific data and ops to the buffer.
 320  * Additionally, provide a name string for exporter; useful in debugging.
 321  *
 322  * @exp_info:   [in]    holds all the export related information provided
 323  *                      by the exporter. see struct dma_buf_export_info
 324  *                      for further details.
 325  *
 326  * Returns, on success, a newly created dma_buf object, which wraps the
 327  * supplied private data and operations for dma_buf_ops. On either missing
 328  * ops, or error in allocating struct dma_buf, will return negative error.
 329  *
 330  */
 331 struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 332 {
 333         struct dma_buf *dmabuf;
 334         struct reservation_object *resv = exp_info->resv;
 335         struct file *file;
 336         size_t alloc_size = sizeof(struct dma_buf);
 337         int ret;
 338
 339         if (!exp_info->resv)
 340                 alloc_size += sizeof(struct reservation_object);
 341         else
 342                 /* prevent &dma_buf[1] == dma_buf->resv */
 343                 alloc_size += 1;
 344
 345         if (WARN_ON(!exp_info->priv
 346                           || !exp_info->ops
 347                           || !exp_info->ops->map_dma_buf
 348                           || !exp_info->ops->unmap_dma_buf
 349                           || !exp_info->ops->release
 350                           || !exp_info->ops->kmap_atomic
 351                           || !exp_info->ops->kmap
 352                           || !exp_info->ops->mmap)) {
 353                 return ERR_PTR(-EINVAL);
 354         }
 355
 356         if (!try_module_get(exp_info->owner))
 357                 return ERR_PTR(-ENOENT);
 358
 359         dmabuf = kzalloc(alloc_size, GFP_KERNEL);
 360         if (!dmabuf) {
 361                 ret = -ENOMEM;
 362                 goto err_module;
 363         }
 364
 365         dmabuf->priv = exp_info->priv;
 366         dmabuf->ops = exp_info->ops;
 367         dmabuf->size = exp_info->size;
 368         dmabuf->exp_name = exp_info->exp_name;
 369         dmabuf->owner = exp_info->owner;
 370         init_waitqueue_head(&dmabuf->poll);
 371         dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
 372         dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
 373
 374         if (!resv) {
 375                 resv = (struct reservation_object *)&dmabuf[1];
 376                 reservation_object_init(resv);
 377         }
 378         dmabuf->resv = resv;
 379
 380         file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
 381                                         exp_info->flags);
 382         if (IS_ERR(file)) {
 383                 ret = PTR_ERR(file);
 384                 goto err_dmabuf;
 385         }
 386
 387         file->f_mode |= FMODE_LSEEK;
 388         dmabuf->file = file;
 389
 390         mutex_init(&dmabuf->lock);
 391         INIT_LIST_HEAD(&dmabuf->attachments);
 392
 393         mutex_lock(&db_list.lock);
 394         list_add(&dmabuf->list_node, &db_list.head);
 395         mutex_unlock(&db_list.lock);
 396
 397         return dmabuf;
 398
 399 err_dmabuf:
 400         kfree(dmabuf);
 401 err_module:
 402         module_put(exp_info->owner);
 403         return ERR_PTR(ret);
 404 }
 405 EXPORT_SYMBOL_GPL(dma_buf_export);
 406
 407 /**
 408  * dma_buf_fd - returns a file descriptor for the given dma_buf
 409  * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
 410  * @flags:      [in]    flags to give to fd
 411  *
 412  * On success, returns an associated 'fd'. Else, returns error.
 413  */
 414 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 415 {
 416         int fd;
 417
 418         if (!dmabuf || !dmabuf->file)
 419                 return -EINVAL;
 420
 421         fd = get_unused_fd_flags(flags);
 422         if (fd < 0)
 423                 return fd;
 424
 425         fd_install(fd, dmabuf->file);
 426
 427         return fd;
 428 }
 429 EXPORT_SYMBOL_GPL(dma_buf_fd);
 430
 431 /**
 432  * dma_buf_get - returns the dma_buf structure related to an fd
 433  * @fd: [in]    fd associated with the dma_buf to be returned
 434  *
 435  * On success, returns the dma_buf structure associated with an fd; uses
 436  * file's refcounting done by fget to increase refcount. returns ERR_PTR
 437  * otherwise.
 438  */
 439 struct dma_buf *dma_buf_get(int fd)
 440 {
 441         struct file *file;
 442
 443         file = fget(fd);
 444
 445         if (!file)
 446                 return ERR_PTR(-EBADF);
 447
 448         if (!is_dma_buf_file(file)) {
 449                 fput(file);
 450                 return ERR_PTR(-EINVAL);
 451         }
 452
 453         return file->private_data;
 454 }
 455 EXPORT_SYMBOL_GPL(dma_buf_get);
 456
 457 /**
 458  * dma_buf_put - decreases refcount of the buffer
 459  * @dmabuf:     [in]    buffer to reduce refcount of
 460  *
 461  * Uses file's refcounting done implicitly by fput()
 462  */
 463 void dma_buf_put(struct dma_buf *dmabuf)
 464 {
 465         if (WARN_ON(!dmabuf || !dmabuf->file))
 466                 return;
 467
 468         fput(dmabuf->file);
 469 }
 470 EXPORT_SYMBOL_GPL(dma_buf_put);
 471
 472 /**
 473  * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 474  * calls attach() of dma_buf_ops to allow device-specific attach functionality
 475  * @dmabuf:     [in]    buffer to attach device to.
 476  * @dev:        [in]    device to be attached.
 477  *
 478  * Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on
 479  * error.
 480  */
 481 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 482                                           struct device *dev)
 483 {
 484         struct dma_buf_attachment *attach;
 485         int ret;
 486
 487         if (WARN_ON(!dmabuf || !dev))
 488                 return ERR_PTR(-EINVAL);
 489
 490         attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 491         if (attach == NULL)
 492                 return ERR_PTR(-ENOMEM);
 493
 494         attach->dev = dev;
 495         attach->dmabuf = dmabuf;
 496
 497         mutex_lock(&dmabuf->lock);
 498
 499         if (dmabuf->ops->attach) {
 500                 ret = dmabuf->ops->attach(dmabuf, dev, attach);
 501                 if (ret)
 502                         goto err_attach;
 503         }
 504         list_add(&attach->node, &dmabuf->attachments);
 505
 506         mutex_unlock(&dmabuf->lock);
 507         return attach;
 508
 509 err_attach:
 510         kfree(attach);
 511         mutex_unlock(&dmabuf->lock);
 512         return ERR_PTR(ret);
 513 }
 514 EXPORT_SYMBOL_GPL(dma_buf_attach);
 515
 516 /**
 517  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 518  * optionally calls detach() of dma_buf_ops for device-specific detach
 519  * @dmabuf:     [in]    buffer to detach from.
 520  * @attach:     [in]    attachment to be detached; is free'd after this call.
 521  *
 522  */
 523 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 524 {
 525         if (WARN_ON(!dmabuf || !attach))
 526                 return;
 527
 528         mutex_lock(&dmabuf->lock);
 529         list_del(&attach->node);
 530         if (dmabuf->ops->detach)
 531                 dmabuf->ops->detach(dmabuf, attach);
 532
 533         mutex_unlock(&dmabuf->lock);
 534         kfree(attach);
 535 }
 536 EXPORT_SYMBOL_GPL(dma_buf_detach);
 537
 538 /**
 539  * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 540  * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 541  * dma_buf_ops.
 542  * @attach:     [in]    attachment whose scatterlist is to be returned
 543  * @direction:  [in]    direction of DMA transfer
 544  *
 545  * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
 546  * on error.
 547  */
 548 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 549                                         enum dma_data_direction direction)
 550 {
 551         struct sg_table *sg_table = ERR_PTR(-EINVAL);
 552
 553         might_sleep();
 554
 555         if (WARN_ON(!attach || !attach->dmabuf))
 556                 return ERR_PTR(-EINVAL);
 557
 558         sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 559         if (!sg_table)
 560                 sg_table = ERR_PTR(-ENOMEM);
 561
 562         return sg_table;
 563 }
 564 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 565
 566 /**
 567  * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 568  * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 569  * dma_buf_ops.
 570  * @attach:     [in]    attachment to unmap buffer from
 571  * @sg_table:   [in]    scatterlist info of the buffer to unmap
 572  * @direction:  [in]    direction of DMA transfer
 573  *
 574  */
 575 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 576                                 struct sg_table *sg_table,
 577                                 enum dma_data_direction direction)
 578 {
 579         might_sleep();
 580
 581         if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
 582                 return;
 583
 584         attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
 585                                                 direction);
 586 }
 587 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
 588
 589 static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 590                                       enum dma_data_direction direction)
 591 {
 592         bool write = (direction == DMA_BIDIRECTIONAL ||
 593                       direction == DMA_TO_DEVICE);
 594         struct reservation_object *resv = dmabuf->resv;
 595         long ret;
 596
 597         /* Wait on any implicit rendering fences */
 598         ret = reservation_object_wait_timeout_rcu(resv, write, true,
 599                                                   MAX_SCHEDULE_TIMEOUT);
 600         if (ret < 0)
 601                 return ret;
 602
 603         return 0;
 604 }
 605
 606 /**
 607  * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
 608  * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
 609  * preparations. Coherency is only guaranteed in the specified range for the
 610  * specified access direction.
 611  * @dmabuf:     [in]    buffer to prepare cpu access for.
 612  * @direction:  [in]    length of range for cpu access.
 613  *
 614  * Can return negative error values, returns 0 on success.
 615  */
 616 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 617                              enum dma_data_direction direction)
 618 {
 619         int ret = 0;
 620
 621         if (WARN_ON(!dmabuf))
 622                 return -EINVAL;
 623
 624         if (dmabuf->ops->begin_cpu_access)
 625                 ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
 626
 627         /* Ensure that all fences are waited upon - but we first allow
 628          * the native handler the chance to do so more efficiently if it
 629          * chooses. A double invocation here will be reasonably cheap no-op.
 630          */
 631         if (ret == 0)
 632                 ret = __dma_buf_begin_cpu_access(dmabuf, direction);
 633
 634         return ret;
 635 }
 636 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
 637
 638 /**
 639  * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
 640  * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
 641  * actions. Coherency is only guaranteed in the specified range for the
 642  * specified access direction.
 643  * @dmabuf:     [in]    buffer to complete cpu access for.
 644  * @direction:  [in]    length of range for cpu access.
 645  *
 646  * Can return negative error values, returns 0 on success.
 647  */
 648 int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 649                            enum dma_data_direction direction)
 650 {
 651         int ret = 0;
 652
 653         WARN_ON(!dmabuf);
 654
 655         if (dmabuf->ops->end_cpu_access)
 656                 ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
 657
 658         return ret;
 659 }
 660 EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 661
 662 /**
 663  * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address
 664  * space. The same restrictions as for kmap_atomic and friends apply.
 665  * @dmabuf:     [in]    buffer to map page from.
 666  * @page_num:   [in]    page in PAGE_SIZE units to map.
 667  *
 668  * This call must always succeed, any necessary preparations that might fail
 669  * need to be done in begin_cpu_access.
 670  */
 671 void *dma_buf_kmap_atomic(struct dma_buf *dmabuf, unsigned long page_num)
 672 {
 673         WARN_ON(!dmabuf);
 674
 675         return dmabuf->ops->kmap_atomic(dmabuf, page_num);
 676 }
 677 EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic);
 678
 679 /**
 680  * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic.
 681  * @dmabuf:     [in]    buffer to unmap page from.
 682  * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 683  * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap_atomic.
 684  *
 685  * This call must always succeed.
 686  */
 687 void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num,
 688                            void *vaddr)
 689 {
 690         WARN_ON(!dmabuf);
 691
 692         if (dmabuf->ops->kunmap_atomic)
 693                 dmabuf->ops->kunmap_atomic(dmabuf, page_num, vaddr);
 694 }
 695 EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic);
 696
 697 /**
 698  * dma_buf_kmap - Map a page of the buffer object into kernel address space. The
 699  * same restrictions as for kmap and friends apply.
 700  * @dmabuf:     [in]    buffer to map page from.
 701  * @page_num:   [in]    page in PAGE_SIZE units to map.
 702  *
 703  * This call must always succeed, any necessary preparations that might fail
 704  * need to be done in begin_cpu_access.
 705  */
 706 void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num)
 707 {
 708         WARN_ON(!dmabuf);
 709
 710         return dmabuf->ops->kmap(dmabuf, page_num);
 711 }
 712 EXPORT_SYMBOL_GPL(dma_buf_kmap);
 713
 714 /**
 715  * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap.
 716  * @dmabuf:     [in]    buffer to unmap page from.
 717  * @page_num:   [in]    page in PAGE_SIZE units to unmap.
 718  * @vaddr:      [in]    kernel space pointer obtained from dma_buf_kmap.
 719  *
 720  * This call must always succeed.
 721  */
 722 void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num,
 723                     void *vaddr)
 724 {
 725         WARN_ON(!dmabuf);
 726
 727         if (dmabuf->ops->kunmap)
 728                 dmabuf->ops->kunmap(dmabuf, page_num, vaddr);
 729 }
 730 EXPORT_SYMBOL_GPL(dma_buf_kunmap);
 731
 732
 733 /**
 734  * dma_buf_mmap - Setup up a userspace mmap with the given vma
 735  * @dmabuf:     [in]    buffer that should back the vma
 736  * @vma:        [in]    vma for the mmap
 737  * @pgoff:      [in]    offset in pages where this mmap should start within the
 738  *                      dma-buf buffer.
 739  *
 740  * This function adjusts the passed in vma so that it points at the file of the
 741  * dma_buf operation. It also adjusts the starting pgoff and does bounds
 742  * checking on the size of the vma. Then it calls the exporters mmap function to
 743  * set up the mapping.
 744  *
 745  * Can return negative error values, returns 0 on success.
 746  */
 747 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 748                  unsigned long pgoff)
 749 {
 750         struct file *oldfile;
 751         int ret;
 752
 753         if (WARN_ON(!dmabuf || !vma))
 754                 return -EINVAL;
 755
 756         /* check for offset overflow */
 757         if (pgoff + vma_pages(vma) < pgoff)
 758                 return -EOVERFLOW;
 759
 760         /* check for overflowing the buffer's size */
 761         if (pgoff + vma_pages(vma) >
 762             dmabuf->size >> PAGE_SHIFT)
 763                 return -EINVAL;
 764
 765         /* readjust the vma */
 766         get_file(dmabuf->file);
 767         oldfile = vma->vm_file;
 768         vma->vm_file = dmabuf->file;
 769         vma->vm_pgoff = pgoff;
 770
 771         ret = dmabuf->ops->mmap(dmabuf, vma);
 772         if (ret) {
 773                 /* restore old parameters on failure */
 774                 vma->vm_file = oldfile;
 775                 fput(dmabuf->file);
 776         } else {
 777                 if (oldfile)
 778                         fput(oldfile);
 779         }
 780         return ret;
 781
 782 }
 783 EXPORT_SYMBOL_GPL(dma_buf_mmap);
 784
 785 /**
 786  * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
 787  * address space. Same restrictions as for vmap and friends apply.
 788  * @dmabuf:     [in]    buffer to vmap
 789  *
 790  * This call may fail due to lack of virtual mapping address space.
 791  * These calls are optional in drivers. The intended use for them
 792  * is for mapping objects linear in kernel space for high use objects.
 793  * Please attempt to use kmap/kunmap before thinking about these interfaces.
 794  *
 795  * Returns NULL on error.
 796  */
 797 void *dma_buf_vmap(struct dma_buf *dmabuf)
 798 {
 799         void *ptr;
 800
 801         if (WARN_ON(!dmabuf))
 802                 return NULL;
 803
 804         if (!dmabuf->ops->vmap)
 805                 return NULL;
 806
 807         mutex_lock(&dmabuf->lock);
 808         if (dmabuf->vmapping_counter) {
 809                 dmabuf->vmapping_counter++;
 810                 BUG_ON(!dmabuf->vmap_ptr);
 811                 ptr = dmabuf->vmap_ptr;
 812                 goto out_unlock;
 813         }
 814
 815         BUG_ON(dmabuf->vmap_ptr);
 816
 817         ptr = dmabuf->ops->vmap(dmabuf);
 818         if (WARN_ON_ONCE(IS_ERR(ptr)))
 819                 ptr = NULL;
 820         if (!ptr)
 821                 goto out_unlock;
 822
 823         dmabuf->vmap_ptr = ptr;
 824         dmabuf->vmapping_counter = 1;
 825
 826 out_unlock:
 827         mutex_unlock(&dmabuf->lock);
 828         return ptr;
 829 }
 830 EXPORT_SYMBOL_GPL(dma_buf_vmap);
 831
 832 /**
 833  * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
 834  * @dmabuf:     [in]    buffer to vunmap
 835  * @vaddr:      [in]    vmap to vunmap
 836  */
 837 void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 838 {
 839         if (WARN_ON(!dmabuf))
 840                 return;
 841
 842         BUG_ON(!dmabuf->vmap_ptr);
 843         BUG_ON(dmabuf->vmapping_counter == 0);
 844         BUG_ON(dmabuf->vmap_ptr != vaddr);
 845
 846         mutex_lock(&dmabuf->lock);
 847         if (--dmabuf->vmapping_counter == 0) {
 848                 if (dmabuf->ops->vunmap)
 849                         dmabuf->ops->vunmap(dmabuf, vaddr);
 850                 dmabuf->vmap_ptr = NULL;
 851         }
 852         mutex_unlock(&dmabuf->lock);
 853 }
 854 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
 855
 856 #ifdef CONFIG_DEBUG_FS
 857 static int dma_buf_debug_show(struct seq_file *s, void *unused)
 858 {
 859         int ret;
 860         struct dma_buf *buf_obj;
 861         struct dma_buf_attachment *attach_obj;
 862         int count = 0, attach_count;
 863         size_t size = 0;
 864
 865         ret = mutex_lock_interruptible(&db_list.lock);
 866
 867         if (ret)
 868                 return ret;
 869
 870         seq_puts(s, "\nDma-buf Objects:\n");
 871         seq_puts(s, "size\tflags\tmode\tcount\texp_name\n");
 872
 873         list_for_each_entry(buf_obj, &db_list.head, list_node) {
 874                 ret = mutex_lock_interruptible(&buf_obj->lock);
 875
 876                 if (ret) {
 877                         seq_puts(s,
 878                                  "\tERROR locking buffer object: skipping\n");
 879                         continue;
 880                 }
 881
 882                 seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\n",
 883                                 buf_obj->size,
 884                                 buf_obj->file->f_flags, buf_obj->file->f_mode,
 885                                 file_count(buf_obj->file),
 886                                 buf_obj->exp_name);
 887
 888                 seq_puts(s, "\tAttached Devices:\n");
 889                 attach_count = 0;
 890
 891                 list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
 892                         seq_puts(s, "\t");
 893
 894                         seq_printf(s, "%s\n", dev_name(attach_obj->dev));
 895                         attach_count++;
 896                 }
 897
 898                 seq_printf(s, "Total %d devices attached\n\n",
 899                                 attach_count);
 900
 901                 count++;
 902                 size += buf_obj->size;
 903                 mutex_unlock(&buf_obj->lock);
 904         }
 905
 906         seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
 907
 908         mutex_unlock(&db_list.lock);
 909         return 0;
 910 }
 911
 912 static int dma_buf_debug_open(struct inode *inode, struct file *file)
 913 {
 914         return single_open(file, dma_buf_debug_show, NULL);
 915 }
 916
 917 static const struct file_operations dma_buf_debug_fops = {
 918         .open           = dma_buf_debug_open,
 919         .read           = seq_read,
 920         .llseek         = seq_lseek,
 921         .release        = single_release,
 922 };
 923
 924 static struct dentry *dma_buf_debugfs_dir;
 925
 926 static int dma_buf_init_debugfs(void)
 927 {
 928         struct dentry *d;
 929         int err = 0;
 930
 931         d = debugfs_create_dir("dma_buf", NULL);
 932         if (IS_ERR(d))
 933                 return PTR_ERR(d);
 934
 935         dma_buf_debugfs_dir = d;
 936
 937         d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,
 938                                 NULL, &dma_buf_debug_fops);
 939         if (IS_ERR(d)) {
 940                 pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
 941                 debugfs_remove_recursive(dma_buf_debugfs_dir);
 942                 dma_buf_debugfs_dir = NULL;
 943                 err = PTR_ERR(d);
 944         }
 945
 946         return err;
 947 }
 948
 949 static void dma_buf_uninit_debugfs(void)
 950 {
 951         if (dma_buf_debugfs_dir)
 952                 debugfs_remove_recursive(dma_buf_debugfs_dir);
 953 }
 954 #else
 955 static inline int dma_buf_init_debugfs(void)
 956 {
 957         return 0;
 958 }
 959 static inline void dma_buf_uninit_debugfs(void)
 960 {
 961 }
 962 #endif
 963
 964 static int __init dma_buf_init(void)
 965 {
 966         mutex_init(&db_list.lock);
 967         INIT_LIST_HEAD(&db_list.head);
 968         dma_buf_init_debugfs();
 969         return 0;
 970 }
 971 subsys_initcall(dma_buf_init);
 972
 973 static void __exit dma_buf_deinit(void)
 974 {
 975         dma_buf_uninit_debugfs();
 976 }
 977 __exitcall(dma_buf_deinit);