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 #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
 338         if (!exp_info->resv)
 339                 alloc_size += sizeof(struct reservation_object);
 340         else
 341                 /* prevent &dma_buf[1] == dma_buf->resv */
 342                 alloc_size += 1;
 343
 344         if (WARN_ON(!exp_info->priv
 345                           || !exp_info->ops
 346                           || !exp_info->ops->map_dma_buf
 347                           || !exp_info->ops->unmap_dma_buf
 348                           || !exp_info->ops->release
 349                           || !exp_info->ops->kmap_atomic
 350                           || !exp_info->ops->kmap
 351                           || !exp_info->ops->mmap)) {
 352                 return ERR_PTR(-EINVAL);
 353         }
 354
 355         if (!try_module_get(exp_info->owner))
 356                 return ERR_PTR(-ENOENT);
 357
 358         dmabuf = kzalloc(alloc_size, GFP_KERNEL);
 359         if (!dmabuf) {
 360                 module_put(exp_info->owner);
 361                 return ERR_PTR(-ENOMEM);
 362         }
 363
 364         dmabuf->priv = exp_info->priv;
 365         dmabuf->ops = exp_info->ops;
 366         dmabuf->size = exp_info->size;
 367         dmabuf->exp_name = exp_info->exp_name;
 368         dmabuf->owner = exp_info->owner;
 369         init_waitqueue_head(&dmabuf->poll);
 370         dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
 371         dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;
 372
 373         if (!resv) {
 374                 resv = (struct reservation_object *)&dmabuf[1];
 375                 reservation_object_init(resv);
 376         }
 377         dmabuf->resv = resv;
 378
 379         file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
 380                                         exp_info->flags);
 381         if (IS_ERR(file)) {
 382                 kfree(dmabuf);
 383                 return ERR_CAST(file);
 384         }
 385
 386         file->f_mode |= FMODE_LSEEK;
 387         dmabuf->file = file;
 388
 389         mutex_init(&dmabuf->lock);
 390         INIT_LIST_HEAD(&dmabuf->attachments);
 391
 392         mutex_lock(&db_list.lock);
 393         list_add(&dmabuf->list_node, &db_list.head);
 394         mutex_unlock(&db_list.lock);
 395
 396         return dmabuf;
 397 }
 398 EXPORT_SYMBOL_GPL(dma_buf_export);
 399
 400 /**
 401  * dma_buf_fd - returns a file descriptor for the given dma_buf
 402  * @dmabuf:     [in]    pointer to dma_buf for which fd is required.
 403  * @flags:      [in]    flags to give to fd
 404  *
 405  * On success, returns an associated 'fd'. Else, returns error.
 406  */
 407 int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 408 {
 409         int fd;
 410
 411         if (!dmabuf || !dmabuf->file)
 412                 return -EINVAL;
 413
 414         fd = get_unused_fd_flags(flags);
 415         if (fd < 0)
 416                 return fd;
 417
 418         fd_install(fd, dmabuf->file);
 419
 420         return fd;
 421 }
 422 EXPORT_SYMBOL_GPL(dma_buf_fd);
 423
 424 /**
 425  * dma_buf_get - returns the dma_buf structure related to an fd
 426  * @fd: [in]    fd associated with the dma_buf to be returned
 427  *
 428  * On success, returns the dma_buf structure associated with an fd; uses
 429  * file's refcounting done by fget to increase refcount. returns ERR_PTR
 430  * otherwise.
 431  */
 432 struct dma_buf *dma_buf_get(int fd)
 433 {
 434         struct file *file;
 435
 436         file = fget(fd);
 437
 438         if (!file)
 439                 return ERR_PTR(-EBADF);
 440
 441         if (!is_dma_buf_file(file)) {
 442                 fput(file);
 443                 return ERR_PTR(-EINVAL);
 444         }
 445
 446         return file->private_data;
 447 }
 448 EXPORT_SYMBOL_GPL(dma_buf_get);
 449
 450 /**
 451  * dma_buf_put - decreases refcount of the buffer
 452  * @dmabuf:     [in]    buffer to reduce refcount of
 453  *
 454  * Uses file's refcounting done implicitly by fput()
 455  */
 456 void dma_buf_put(struct dma_buf *dmabuf)
 457 {
 458         if (WARN_ON(!dmabuf || !dmabuf->file))
 459                 return;
 460
 461         fput(dmabuf->file);
 462 }
 463 EXPORT_SYMBOL_GPL(dma_buf_put);
 464
 465 /**
 466  * dma_buf_attach - Add the device to dma_buf's attachments list; optionally,
 467  * calls attach() of dma_buf_ops to allow device-specific attach functionality
 468  * @dmabuf:     [in]    buffer to attach device to.
 469  * @dev:        [in]    device to be attached.
 470  *
 471  * Returns struct dma_buf_attachment * for this attachment; returns ERR_PTR on
 472  * error.
 473  */
 474 struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 475                                           struct device *dev)
 476 {
 477         struct dma_buf_attachment *attach;
 478         int ret;
 479
 480         if (WARN_ON(!dmabuf || !dev))
 481                 return ERR_PTR(-EINVAL);
 482
 483         attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 484         if (attach == NULL)
 485                 return ERR_PTR(-ENOMEM);
 486
 487         attach->dev = dev;
 488         attach->dmabuf = dmabuf;
 489
 490         mutex_lock(&dmabuf->lock);
 491
 492         if (dmabuf->ops->attach) {
 493                 ret = dmabuf->ops->attach(dmabuf, dev, attach);
 494                 if (ret)
 495                         goto err_attach;
 496         }
 497         list_add(&attach->node, &dmabuf->attachments);
 498
 499         mutex_unlock(&dmabuf->lock);
 500         return attach;
 501
 502 err_attach:
 503         kfree(attach);
 504         mutex_unlock(&dmabuf->lock);
 505         return ERR_PTR(ret);
 506 }
 507 EXPORT_SYMBOL_GPL(dma_buf_attach);
 508
 509 /**
 510  * dma_buf_detach - Remove the given attachment from dmabuf's attachments list;
 511  * optionally calls detach() of dma_buf_ops for device-specific detach
 512  * @dmabuf:     [in]    buffer to detach from.
 513  * @attach:     [in]    attachment to be detached; is free'd after this call.
 514  *
 515  */
 516 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 517 {
 518         if (WARN_ON(!dmabuf || !attach))
 519                 return;
 520
 521         mutex_lock(&dmabuf->lock);
 522         list_del(&attach->node);
 523         if (dmabuf->ops->detach)
 524                 dmabuf->ops->detach(dmabuf, attach);
 525
 526         mutex_unlock(&dmabuf->lock);
 527         kfree(attach);
 528 }
 529 EXPORT_SYMBOL_GPL(dma_buf_detach);
 530
 531 /**
 532  * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
 533  * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
 534  * dma_buf_ops.
 535  * @attach:     [in]    attachment whose scatterlist is to be returned
 536  * @direction:  [in]    direction of DMA transfer
 537  *
 538  * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
 539  * on error.
 540  */
 541 struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 542                                         enum dma_data_direction direction)
 543 {
 544         struct sg_table *sg_table = ERR_PTR(-EINVAL);
 545
 546         might_sleep();
 547
 548         if (WARN_ON(!attach || !attach->dmabuf))
 549                 return ERR_PTR(-EINVAL);
 550
 551         sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 552         if (!sg_table)
 553                 sg_table = ERR_PTR(-ENOMEM);
 554
 555         return sg_table;
 556 }
 557 EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 558
 559 /**
 560  * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
 561  * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
 562  * dma_buf_ops.
 563  * @attach:     [in]    attachment to unmap buffer from
 564  * @sg_table:   [in]    scatterlist info of the buffer to unmap
 565  * @direction:  [in]    direction of DMA transfer
 566  *
 567  */
 568 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 569                                 struct sg_table *sg_table,
 570                                 enum dma_data_direction direction)
 571 {
 572         might_sleep();
 573
 574         if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
 575                 return;
 576
 577         attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
 578                                                 direction);
 579 }
 580 EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment);
 581
 582
 583 /**
 584  * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
 585  * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
 586  * preparations. Coherency is only guaranteed in the specified range for the
 587  * specified access direction.
 588  * @dmabuf:     [in]    buffer to prepare cpu access for.
 589  * @direction:  [in]    length of range for cpu access.
 590  *
 591  * Can return negative error values, returns 0 on success.
 592  */
 593 int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 594                              enum dma_data_direction direction)
 595 {
 596         int ret = 0;
 597
 598         if (WARN_ON(!dmabuf))
 599                 return -EINVAL;
 600
 601         if (dmabuf->ops->begin_cpu_access)
 602                 ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
 603
 604         return ret;
 605 }
 606 EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access);
 607
 608 /**
 609  * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
 610  * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
 611  * actions. Coherency is only guaranteed in the specified range for the
 612  * specified access direction.
 613  * @dmabuf:     [in]    buffer to complete cpu access for.
 614  * @direction:  [in]    length of range for cpu access.
 615  *
 616  * Can return negative error values, returns 0 on success.
 617  */
 618 int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 619                            enum dma_data_direction direction)
 620 {
 621         int ret = 0;
 622
 623         WARN_ON(!dmabuf);
 624
 625         if (dmabuf->ops->end_cpu_access)
 626                 ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
 627
 628         return ret;
 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_pages(vma) < pgoff)
 728                 return -EOVERFLOW;
 729
 730         /* check for overflowing the buffer's size */
 731         if (pgoff + vma_pages(vma) >
 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);