Pileus Git - ~andy/linux/blob - drivers/media/v4l2-core/videobuf2-dma-contig.c

   1 /*
   2  * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
   3  *
   4  * Copyright (C) 2010 Samsung Electronics
   5  *
   6  * Author: Pawel Osciak <pawel@osciak.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation.
  11  */
  12
  13 #include <linux/dma-buf.h>
  14 #include <linux/module.h>
  15 #include <linux/scatterlist.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/dma-mapping.h>
  19
  20 #include <media/videobuf2-core.h>
  21 #include <media/videobuf2-dma-contig.h>
  22 #include <media/videobuf2-memops.h>
  23
  24 struct vb2_dc_conf {
  25         struct device           *dev;
  26 };
  27
  28 struct vb2_dc_buf {
  29         struct device                   *dev;
  30         void                            *vaddr;
  31         unsigned long                   size;
  32         dma_addr_t                      dma_addr;
  33         enum dma_data_direction         dma_dir;
  34         struct sg_table                 *dma_sgt;
  35
  36         /* MMAP related */
  37         struct vb2_vmarea_handler       handler;
  38         atomic_t                        refcount;
  39         struct sg_table                 *sgt_base;
  40
  41         /* USERPTR related */
  42         struct vm_area_struct           *vma;
  43
  44         /* DMABUF related */
  45         struct dma_buf_attachment       *db_attach;
  46 };
  47
  48 /*********************************************/
  49 /*        scatterlist table functions        */
  50 /*********************************************/
  51
  52
  53 static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
  54         void (*cb)(struct page *pg))
  55 {
  56         struct scatterlist *s;
  57         unsigned int i;
  58
  59         for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
  60                 struct page *page = sg_page(s);
  61                 unsigned int n_pages = PAGE_ALIGN(s->offset + s->length)
  62                         >> PAGE_SHIFT;
  63                 unsigned int j;
  64
  65                 for (j = 0; j < n_pages; ++j, ++page)
  66                         cb(page);
  67         }
  68 }
  69
  70 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  71 {
  72         struct scatterlist *s;
  73         dma_addr_t expected = sg_dma_address(sgt->sgl);
  74         unsigned int i;
  75         unsigned long size = 0;
  76
  77         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  78                 if (sg_dma_address(s) != expected)
  79                         break;
  80                 expected = sg_dma_address(s) + sg_dma_len(s);
  81                 size += sg_dma_len(s);
  82         }
  83         return size;
  84 }
  85
  86 /*********************************************/
  87 /*         callbacks for all buffers         */
  88 /*********************************************/
  89
  90 static void *vb2_dc_cookie(void *buf_priv)
  91 {
  92         struct vb2_dc_buf *buf = buf_priv;
  93
  94         return &buf->dma_addr;
  95 }
  96
  97 static void *vb2_dc_vaddr(void *buf_priv)
  98 {
  99         struct vb2_dc_buf *buf = buf_priv;
 100
 101         return buf->vaddr;
 102 }
 103
 104 static unsigned int vb2_dc_num_users(void *buf_priv)
 105 {
 106         struct vb2_dc_buf *buf = buf_priv;
 107
 108         return atomic_read(&buf->refcount);
 109 }
 110
 111 static void vb2_dc_prepare(void *buf_priv)
 112 {
 113         struct vb2_dc_buf *buf = buf_priv;
 114         struct sg_table *sgt = buf->dma_sgt;
 115
 116         /* DMABUF exporter will flush the cache for us */
 117         if (!sgt || buf->db_attach)
 118                 return;
 119
 120         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 121 }
 122
 123 static void vb2_dc_finish(void *buf_priv)
 124 {
 125         struct vb2_dc_buf *buf = buf_priv;
 126         struct sg_table *sgt = buf->dma_sgt;
 127
 128         /* DMABUF exporter will flush the cache for us */
 129         if (!sgt || buf->db_attach)
 130                 return;
 131
 132         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 133 }
 134
 135 /*********************************************/
 136 /*        callbacks for MMAP buffers         */
 137 /*********************************************/
 138
 139 static void vb2_dc_put(void *buf_priv)
 140 {
 141         struct vb2_dc_buf *buf = buf_priv;
 142
 143         if (!atomic_dec_and_test(&buf->refcount))
 144                 return;
 145
 146         if (buf->sgt_base) {
 147                 sg_free_table(buf->sgt_base);
 148                 kfree(buf->sgt_base);
 149         }
 150         dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
 151         put_device(buf->dev);
 152         kfree(buf);
 153 }
 154
 155 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 156 {
 157         struct vb2_dc_conf *conf = alloc_ctx;
 158         struct device *dev = conf->dev;
 159         struct vb2_dc_buf *buf;
 160
 161         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 162         if (!buf)
 163                 return ERR_PTR(-ENOMEM);
 164
 165         buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr, GFP_KERNEL);
 166         if (!buf->vaddr) {
 167                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 168                 kfree(buf);
 169                 return ERR_PTR(-ENOMEM);
 170         }
 171
 172         /* Prevent the device from being released while the buffer is used */
 173         buf->dev = get_device(dev);
 174         buf->size = size;
 175
 176         buf->handler.refcount = &buf->refcount;
 177         buf->handler.put = vb2_dc_put;
 178         buf->handler.arg = buf;
 179
 180         atomic_inc(&buf->refcount);
 181
 182         return buf;
 183 }
 184
 185 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 186 {
 187         struct vb2_dc_buf *buf = buf_priv;
 188         int ret;
 189
 190         if (!buf) {
 191                 printk(KERN_ERR "No buffer to map\n");
 192                 return -EINVAL;
 193         }
 194
 195         /*
 196          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 197          * map whole buffer
 198          */
 199         vma->vm_pgoff = 0;
 200
 201         ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
 202                 buf->dma_addr, buf->size);
 203
 204         if (ret) {
 205                 pr_err("Remapping memory failed, error: %d\n", ret);
 206                 return ret;
 207         }
 208
 209         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 210         vma->vm_private_data    = &buf->handler;
 211         vma->vm_ops             = &vb2_common_vm_ops;
 212
 213         vma->vm_ops->open(vma);
 214
 215         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 216                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 217                 buf->size);
 218
 219         return 0;
 220 }
 221
 222 /*********************************************/
 223 /*         DMABUF ops for exporters          */
 224 /*********************************************/
 225
 226 struct vb2_dc_attachment {
 227         struct sg_table sgt;
 228         enum dma_data_direction dir;
 229 };
 230
 231 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 232         struct dma_buf_attachment *dbuf_attach)
 233 {
 234         struct vb2_dc_attachment *attach;
 235         unsigned int i;
 236         struct scatterlist *rd, *wr;
 237         struct sg_table *sgt;
 238         struct vb2_dc_buf *buf = dbuf->priv;
 239         int ret;
 240
 241         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 242         if (!attach)
 243                 return -ENOMEM;
 244
 245         sgt = &attach->sgt;
 246         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 247          * map the same scatter list to multiple attachments at the same time.
 248          */
 249         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 250         if (ret) {
 251                 kfree(attach);
 252                 return -ENOMEM;
 253         }
 254
 255         rd = buf->sgt_base->sgl;
 256         wr = sgt->sgl;
 257         for (i = 0; i < sgt->orig_nents; ++i) {
 258                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 259                 rd = sg_next(rd);
 260                 wr = sg_next(wr);
 261         }
 262
 263         attach->dir = DMA_NONE;
 264         dbuf_attach->priv = attach;
 265
 266         return 0;
 267 }
 268
 269 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 270         struct dma_buf_attachment *db_attach)
 271 {
 272         struct vb2_dc_attachment *attach = db_attach->priv;
 273         struct sg_table *sgt;
 274
 275         if (!attach)
 276                 return;
 277
 278         sgt = &attach->sgt;
 279
 280         /* release the scatterlist cache */
 281         if (attach->dir != DMA_NONE)
 282                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 283                         attach->dir);
 284         sg_free_table(sgt);
 285         kfree(attach);
 286         db_attach->priv = NULL;
 287 }
 288
 289 static struct sg_table *vb2_dc_dmabuf_ops_map(
 290         struct dma_buf_attachment *db_attach, enum dma_data_direction dir)
 291 {
 292         struct vb2_dc_attachment *attach = db_attach->priv;
 293         /* stealing dmabuf mutex to serialize map/unmap operations */
 294         struct mutex *lock = &db_attach->dmabuf->lock;
 295         struct sg_table *sgt;
 296         int ret;
 297
 298         mutex_lock(lock);
 299
 300         sgt = &attach->sgt;
 301         /* return previously mapped sg table */
 302         if (attach->dir == dir) {
 303                 mutex_unlock(lock);
 304                 return sgt;
 305         }
 306
 307         /* release any previous cache */
 308         if (attach->dir != DMA_NONE) {
 309                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 310                         attach->dir);
 311                 attach->dir = DMA_NONE;
 312         }
 313
 314         /* mapping to the client with new direction */
 315         ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
 316         if (ret <= 0) {
 317                 pr_err("failed to map scatterlist\n");
 318                 mutex_unlock(lock);
 319                 return ERR_PTR(-EIO);
 320         }
 321
 322         attach->dir = dir;
 323
 324         mutex_unlock(lock);
 325
 326         return sgt;
 327 }
 328
 329 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 330         struct sg_table *sgt, enum dma_data_direction dir)
 331 {
 332         /* nothing to be done here */
 333 }
 334
 335 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 336 {
 337         /* drop reference obtained in vb2_dc_get_dmabuf */
 338         vb2_dc_put(dbuf->priv);
 339 }
 340
 341 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 342 {
 343         struct vb2_dc_buf *buf = dbuf->priv;
 344
 345         return buf->vaddr + pgnum * PAGE_SIZE;
 346 }
 347
 348 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 349 {
 350         struct vb2_dc_buf *buf = dbuf->priv;
 351
 352         return buf->vaddr;
 353 }
 354
 355 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 356         struct vm_area_struct *vma)
 357 {
 358         return vb2_dc_mmap(dbuf->priv, vma);
 359 }
 360
 361 static struct dma_buf_ops vb2_dc_dmabuf_ops = {
 362         .attach = vb2_dc_dmabuf_ops_attach,
 363         .detach = vb2_dc_dmabuf_ops_detach,
 364         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 365         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 366         .kmap = vb2_dc_dmabuf_ops_kmap,
 367         .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
 368         .vmap = vb2_dc_dmabuf_ops_vmap,
 369         .mmap = vb2_dc_dmabuf_ops_mmap,
 370         .release = vb2_dc_dmabuf_ops_release,
 371 };
 372
 373 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 374 {
 375         int ret;
 376         struct sg_table *sgt;
 377
 378         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 379         if (!sgt) {
 380                 dev_err(buf->dev, "failed to alloc sg table\n");
 381                 return NULL;
 382         }
 383
 384         ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
 385                 buf->size);
 386         if (ret < 0) {
 387                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 388                 kfree(sgt);
 389                 return NULL;
 390         }
 391
 392         return sgt;
 393 }
 394
 395 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv)
 396 {
 397         struct vb2_dc_buf *buf = buf_priv;
 398         struct dma_buf *dbuf;
 399
 400         if (!buf->sgt_base)
 401                 buf->sgt_base = vb2_dc_get_base_sgt(buf);
 402
 403         if (WARN_ON(!buf->sgt_base))
 404                 return NULL;
 405
 406         dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, 0);
 407         if (IS_ERR(dbuf))
 408                 return NULL;
 409
 410         /* dmabuf keeps reference to vb2 buffer */
 411         atomic_inc(&buf->refcount);
 412
 413         return dbuf;
 414 }
 415
 416 /*********************************************/
 417 /*       callbacks for USERPTR buffers       */
 418 /*********************************************/
 419
 420 static inline int vma_is_io(struct vm_area_struct *vma)
 421 {
 422         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 423 }
 424
 425 static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
 426         int n_pages, struct vm_area_struct *vma, int write)
 427 {
 428         if (vma_is_io(vma)) {
 429                 unsigned int i;
 430
 431                 for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
 432                         unsigned long pfn;
 433                         int ret = follow_pfn(vma, start, &pfn);
 434
 435                         if (ret) {
 436                                 pr_err("no page for address %lu\n", start);
 437                                 return ret;
 438                         }
 439                         pages[i] = pfn_to_page(pfn);
 440                 }
 441         } else {
 442                 int n;
 443
 444                 n = get_user_pages(current, current->mm, start & PAGE_MASK,
 445                         n_pages, write, 1, pages, NULL);
 446                 /* negative error means that no page was pinned */
 447                 n = max(n, 0);
 448                 if (n != n_pages) {
 449                         pr_err("got only %d of %d user pages\n", n, n_pages);
 450                         while (n)
 451                                 put_page(pages[--n]);
 452                         return -EFAULT;
 453                 }
 454         }
 455
 456         return 0;
 457 }
 458
 459 static void vb2_dc_put_dirty_page(struct page *page)
 460 {
 461         set_page_dirty_lock(page);
 462         put_page(page);
 463 }
 464
 465 static void vb2_dc_put_userptr(void *buf_priv)
 466 {
 467         struct vb2_dc_buf *buf = buf_priv;
 468         struct sg_table *sgt = buf->dma_sgt;
 469
 470         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 471         if (!vma_is_io(buf->vma))
 472                 vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
 473
 474         sg_free_table(sgt);
 475         kfree(sgt);
 476         vb2_put_vma(buf->vma);
 477         kfree(buf);
 478 }
 479
 480 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 481         unsigned long size, int write)
 482 {
 483         struct vb2_dc_conf *conf = alloc_ctx;
 484         struct vb2_dc_buf *buf;
 485         unsigned long start;
 486         unsigned long end;
 487         unsigned long offset;
 488         struct page **pages;
 489         int n_pages;
 490         int ret = 0;
 491         struct vm_area_struct *vma;
 492         struct sg_table *sgt;
 493         unsigned long contig_size;
 494
 495         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 496         if (!buf)
 497                 return ERR_PTR(-ENOMEM);
 498
 499         buf->dev = conf->dev;
 500         buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 501
 502         start = vaddr & PAGE_MASK;
 503         offset = vaddr & ~PAGE_MASK;
 504         end = PAGE_ALIGN(vaddr + size);
 505         n_pages = (end - start) >> PAGE_SHIFT;
 506
 507         pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
 508         if (!pages) {
 509                 ret = -ENOMEM;
 510                 pr_err("failed to allocate pages table\n");
 511                 goto fail_buf;
 512         }
 513
 514         /* current->mm->mmap_sem is taken by videobuf2 core */
 515         vma = find_vma(current->mm, vaddr);
 516         if (!vma) {
 517                 pr_err("no vma for address %lu\n", vaddr);
 518                 ret = -EFAULT;
 519                 goto fail_pages;
 520         }
 521
 522         if (vma->vm_end < vaddr + size) {
 523                 pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
 524                 ret = -EFAULT;
 525                 goto fail_pages;
 526         }
 527
 528         buf->vma = vb2_get_vma(vma);
 529         if (!buf->vma) {
 530                 pr_err("failed to copy vma\n");
 531                 ret = -ENOMEM;
 532                 goto fail_pages;
 533         }
 534
 535         /* extract page list from userspace mapping */
 536         ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, write);
 537         if (ret) {
 538                 pr_err("failed to get user pages\n");
 539                 goto fail_vma;
 540         }
 541
 542         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 543         if (!sgt) {
 544                 pr_err("failed to allocate sg table\n");
 545                 ret = -ENOMEM;
 546                 goto fail_get_user_pages;
 547         }
 548
 549         ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
 550                 offset, size, GFP_KERNEL);
 551         if (ret) {
 552                 pr_err("failed to initialize sg table\n");
 553                 goto fail_sgt;
 554         }
 555
 556         /* pages are no longer needed */
 557         kfree(pages);
 558         pages = NULL;
 559
 560         sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
 561                 buf->dma_dir);
 562         if (sgt->nents <= 0) {
 563                 pr_err("failed to map scatterlist\n");
 564                 ret = -EIO;
 565                 goto fail_sgt_init;
 566         }
 567
 568         contig_size = vb2_dc_get_contiguous_size(sgt);
 569         if (contig_size < size) {
 570                 pr_err("contiguous mapping is too small %lu/%lu\n",
 571                         contig_size, size);
 572                 ret = -EFAULT;
 573                 goto fail_map_sg;
 574         }
 575
 576         buf->dma_addr = sg_dma_address(sgt->sgl);
 577         buf->size = size;
 578         buf->dma_sgt = sgt;
 579
 580         return buf;
 581
 582 fail_map_sg:
 583         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 584
 585 fail_sgt_init:
 586         if (!vma_is_io(buf->vma))
 587                 vb2_dc_sgt_foreach_page(sgt, put_page);
 588         sg_free_table(sgt);
 589
 590 fail_sgt:
 591         kfree(sgt);
 592
 593 fail_get_user_pages:
 594         if (pages && !vma_is_io(buf->vma))
 595                 while (n_pages)
 596                         put_page(pages[--n_pages]);
 597
 598 fail_vma:
 599         vb2_put_vma(buf->vma);
 600
 601 fail_pages:
 602         kfree(pages); /* kfree is NULL-proof */
 603
 604 fail_buf:
 605         kfree(buf);
 606
 607         return ERR_PTR(ret);
 608 }
 609
 610 /*********************************************/
 611 /*       callbacks for DMABUF buffers        */
 612 /*********************************************/
 613
 614 static int vb2_dc_map_dmabuf(void *mem_priv)
 615 {
 616         struct vb2_dc_buf *buf = mem_priv;
 617         struct sg_table *sgt;
 618         unsigned long contig_size;
 619
 620         if (WARN_ON(!buf->db_attach)) {
 621                 pr_err("trying to pin a non attached buffer\n");
 622                 return -EINVAL;
 623         }
 624
 625         if (WARN_ON(buf->dma_sgt)) {
 626                 pr_err("dmabuf buffer is already pinned\n");
 627                 return 0;
 628         }
 629
 630         /* get the associated scatterlist for this buffer */
 631         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 632         if (IS_ERR_OR_NULL(sgt)) {
 633                 pr_err("Error getting dmabuf scatterlist\n");
 634                 return -EINVAL;
 635         }
 636
 637         /* checking if dmabuf is big enough to store contiguous chunk */
 638         contig_size = vb2_dc_get_contiguous_size(sgt);
 639         if (contig_size < buf->size) {
 640                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 641                         contig_size, buf->size);
 642                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 643                 return -EFAULT;
 644         }
 645
 646         buf->dma_addr = sg_dma_address(sgt->sgl);
 647         buf->dma_sgt = sgt;
 648
 649         return 0;
 650 }
 651
 652 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 653 {
 654         struct vb2_dc_buf *buf = mem_priv;
 655         struct sg_table *sgt = buf->dma_sgt;
 656
 657         if (WARN_ON(!buf->db_attach)) {
 658                 pr_err("trying to unpin a not attached buffer\n");
 659                 return;
 660         }
 661
 662         if (WARN_ON(!sgt)) {
 663                 pr_err("dmabuf buffer is already unpinned\n");
 664                 return;
 665         }
 666
 667         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 668
 669         buf->dma_addr = 0;
 670         buf->dma_sgt = NULL;
 671 }
 672
 673 static void vb2_dc_detach_dmabuf(void *mem_priv)
 674 {
 675         struct vb2_dc_buf *buf = mem_priv;
 676
 677         /* if vb2 works correctly you should never detach mapped buffer */
 678         if (WARN_ON(buf->dma_addr))
 679                 vb2_dc_unmap_dmabuf(buf);
 680
 681         /* detach this attachment */
 682         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 683         kfree(buf);
 684 }
 685
 686 static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 687         unsigned long size, int write)
 688 {
 689         struct vb2_dc_conf *conf = alloc_ctx;
 690         struct vb2_dc_buf *buf;
 691         struct dma_buf_attachment *dba;
 692
 693         if (dbuf->size < size)
 694                 return ERR_PTR(-EFAULT);
 695
 696         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 697         if (!buf)
 698                 return ERR_PTR(-ENOMEM);
 699
 700         buf->dev = conf->dev;
 701         /* create attachment for the dmabuf with the user device */
 702         dba = dma_buf_attach(dbuf, buf->dev);
 703         if (IS_ERR(dba)) {
 704                 pr_err("failed to attach dmabuf\n");
 705                 kfree(buf);
 706                 return dba;
 707         }
 708
 709         buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 710         buf->size = size;
 711         buf->db_attach = dba;
 712
 713         return buf;
 714 }
 715
 716 /*********************************************/
 717 /*       DMA CONTIG exported functions       */
 718 /*********************************************/
 719
 720 const struct vb2_mem_ops vb2_dma_contig_memops = {
 721         .alloc          = vb2_dc_alloc,
 722         .put            = vb2_dc_put,
 723         .get_dmabuf     = vb2_dc_get_dmabuf,
 724         .cookie         = vb2_dc_cookie,
 725         .vaddr          = vb2_dc_vaddr,
 726         .mmap           = vb2_dc_mmap,
 727         .get_userptr    = vb2_dc_get_userptr,
 728         .put_userptr    = vb2_dc_put_userptr,
 729         .prepare        = vb2_dc_prepare,
 730         .finish         = vb2_dc_finish,
 731         .map_dmabuf     = vb2_dc_map_dmabuf,
 732         .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
 733         .attach_dmabuf  = vb2_dc_attach_dmabuf,
 734         .detach_dmabuf  = vb2_dc_detach_dmabuf,
 735         .num_users      = vb2_dc_num_users,
 736 };
 737 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 738
 739 void *vb2_dma_contig_init_ctx(struct device *dev)
 740 {
 741         struct vb2_dc_conf *conf;
 742
 743         conf = kzalloc(sizeof *conf, GFP_KERNEL);
 744         if (!conf)
 745                 return ERR_PTR(-ENOMEM);
 746
 747         conf->dev = dev;
 748
 749         return conf;
 750 }
 751 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
 752
 753 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 754 {
 755         kfree(alloc_ctx);
 756 }
 757 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 758
 759 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 760 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 761 MODULE_LICENSE("GPL");