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