drivers/media/v4l2-core/videobuf2-dma-sg.c

   1 /*
   2  * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
   3  *
   4  * Copyright (C) 2010 Samsung Electronics
   5  *
   6  * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.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/module.h>
  14 #include <linux/mm.h>
  15 #include <linux/scatterlist.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19
  20 #include <media/videobuf2-core.h>
  21 #include <media/videobuf2-memops.h>
  22 #include <media/videobuf2-dma-sg.h>
  23
  24 static int debug;
  25 module_param(debug, int, 0644);
  26
  27 #define dprintk(level, fmt, arg...)                                     \
  28         do {                                                            \
  29                 if (debug >= level)                                     \
  30                         printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg);  \
  31         } while (0)
  32
  33 struct vb2_dma_sg_conf {
  34         struct device           *dev;
  35 };
  36
  37 struct vb2_dma_sg_buf {
  38         struct device                   *dev;
  39         void                            *vaddr;
  40         struct page                     **pages;
  41         int                             offset;
  42         enum dma_data_direction         dma_dir;
  43         struct sg_table                 sg_table;
  44         /*
  45          * This will point to sg_table when used with the MMAP or USERPTR
  46          * memory model, and to the dma_buf sglist when used with the
  47          * DMABUF memory model.
  48          */
  49         struct sg_table                 *dma_sgt;
  50         size_t                          size;
  51         unsigned int                    num_pages;
  52         atomic_t                        refcount;
  53         struct vb2_vmarea_handler       handler;
  54         struct vm_area_struct           *vma;
  55
  56         struct dma_buf_attachment       *db_attach;
  57 };
  58
  59 static void vb2_dma_sg_put(void *buf_priv);
  60
  61 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
  62                 gfp_t gfp_flags)
  63 {
  64         unsigned int last_page = 0;
  65         int size = buf->size;
  66
  67         while (size > 0) {
  68                 struct page *pages;
  69                 int order;
  70                 int i;
  71
  72                 order = get_order(size);
  73                 /* Dont over allocate*/
  74                 if ((PAGE_SIZE << order) > size)
  75                         order--;
  76
  77                 pages = NULL;
  78                 while (!pages) {
  79                         pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
  80                                         __GFP_NOWARN | gfp_flags, order);
  81                         if (pages)
  82                                 break;
  83
  84                         if (order == 0) {
  85                                 while (last_page--)
  86                                         __free_page(buf->pages[last_page]);
  87                                 return -ENOMEM;
  88                         }
  89                         order--;
  90                 }
  91
  92                 split_page(pages, order);
  93                 for (i = 0; i < (1 << order); i++)
  94                         buf->pages[last_page++] = &pages[i];
  95
  96                 size -= PAGE_SIZE << order;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size,
 103                               enum dma_data_direction dma_dir, gfp_t gfp_flags)
 104 {
 105         struct vb2_dma_sg_conf *conf = alloc_ctx;
 106         struct vb2_dma_sg_buf *buf;
 107         struct sg_table *sgt;
 108         int ret;
 109         int num_pages;
 110         DEFINE_DMA_ATTRS(attrs);
 111
 112         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 113
 114         if (WARN_ON(alloc_ctx == NULL))
 115                 return NULL;
 116         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 117         if (!buf)
 118                 return NULL;
 119
 120         buf->vaddr = NULL;
 121         buf->dma_dir = dma_dir;
 122         buf->offset = 0;
 123         buf->size = size;
 124         /* size is already page aligned */
 125         buf->num_pages = size >> PAGE_SHIFT;
 126         buf->dma_sgt = &buf->sg_table;
 127
 128         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 129                              GFP_KERNEL);
 130         if (!buf->pages)
 131                 goto fail_pages_array_alloc;
 132
 133         ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
 134         if (ret)
 135                 goto fail_pages_alloc;
 136
 137         ret = sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 138                         buf->num_pages, 0, size, GFP_KERNEL);
 139         if (ret)
 140                 goto fail_table_alloc;
 141
 142         /* Prevent the device from being released while the buffer is used */
 143         buf->dev = get_device(conf->dev);
 144
 145         sgt = &buf->sg_table;
 146         /*
 147          * No need to sync to the device, this will happen later when the
 148          * prepare() memop is called.
 149          */
 150         if (dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
 151                              buf->dma_dir, &attrs) == 0)
 152                 goto fail_map;
 153
 154         buf->handler.refcount = &buf->refcount;
 155         buf->handler.put = vb2_dma_sg_put;
 156         buf->handler.arg = buf;
 157
 158         atomic_inc(&buf->refcount);
 159
 160         dprintk(1, "%s: Allocated buffer of %d pages\n",
 161                 __func__, buf->num_pages);
 162         return buf;
 163
 164 fail_map:
 165         put_device(buf->dev);
 166         sg_free_table(buf->dma_sgt);
 167 fail_table_alloc:
 168         num_pages = buf->num_pages;
 169         while (num_pages--)
 170                 __free_page(buf->pages[num_pages]);
 171 fail_pages_alloc:
 172         kfree(buf->pages);
 173 fail_pages_array_alloc:
 174         kfree(buf);
 175         return NULL;
 176 }
 177
 178 static void vb2_dma_sg_put(void *buf_priv)
 179 {
 180         struct vb2_dma_sg_buf *buf = buf_priv;
 181         struct sg_table *sgt = &buf->sg_table;
 182         int i = buf->num_pages;
 183
 184         if (atomic_dec_and_test(&buf->refcount)) {
 185                 DEFINE_DMA_ATTRS(attrs);
 186
 187                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 188                 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 189                         buf->num_pages);
 190                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
 191                                    buf->dma_dir, &attrs);
 192                 if (buf->vaddr)
 193                         vm_unmap_ram(buf->vaddr, buf->num_pages);
 194                 sg_free_table(buf->dma_sgt);
 195                 while (--i >= 0)
 196                         __free_page(buf->pages[i]);
 197                 kfree(buf->pages);
 198                 put_device(buf->dev);
 199                 kfree(buf);
 200         }
 201 }
 202
 203 static void vb2_dma_sg_prepare(void *buf_priv)
 204 {
 205         struct vb2_dma_sg_buf *buf = buf_priv;
 206         struct sg_table *sgt = buf->dma_sgt;
 207
 208         /* DMABUF exporter will flush the cache for us */
 209         if (buf->db_attach)
 210                 return;
 211
 212         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 213 }
 214
 215 static void vb2_dma_sg_finish(void *buf_priv)
 216 {
 217         struct vb2_dma_sg_buf *buf = buf_priv;
 218         struct sg_table *sgt = buf->dma_sgt;
 219
 220         /* DMABUF exporter will flush the cache for us */
 221         if (buf->db_attach)
 222                 return;
 223
 224         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 225 }
 226
 227 static inline int vma_is_io(struct vm_area_struct *vma)
 228 {
 229         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 230 }
 231
 232 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 233                                     unsigned long size,
 234                                     enum dma_data_direction dma_dir)
 235 {
 236         struct vb2_dma_sg_conf *conf = alloc_ctx;
 237         struct vb2_dma_sg_buf *buf;
 238         unsigned long first, last;
 239         int num_pages_from_user;
 240         struct vm_area_struct *vma;
 241         struct sg_table *sgt;
 242         DEFINE_DMA_ATTRS(attrs);
 243
 244         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 245
 246         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 247         if (!buf)
 248                 return NULL;
 249
 250         buf->vaddr = NULL;
 251         buf->dev = conf->dev;
 252         buf->dma_dir = dma_dir;
 253         buf->offset = vaddr & ~PAGE_MASK;
 254         buf->size = size;
 255         buf->dma_sgt = &buf->sg_table;
 256
 257         first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
 258         last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
 259         buf->num_pages = last - first + 1;
 260
 261         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 262                              GFP_KERNEL);
 263         if (!buf->pages)
 264                 goto userptr_fail_alloc_pages;
 265
 266         vma = find_vma(current->mm, vaddr);
 267         if (!vma) {
 268                 dprintk(1, "no vma for address %lu\n", vaddr);
 269                 goto userptr_fail_find_vma;
 270         }
 271
 272         if (vma->vm_end < vaddr + size) {
 273                 dprintk(1, "vma at %lu is too small for %lu bytes\n",
 274                         vaddr, size);
 275                 goto userptr_fail_find_vma;
 276         }
 277
 278         buf->vma = vb2_get_vma(vma);
 279         if (!buf->vma) {
 280                 dprintk(1, "failed to copy vma\n");
 281                 goto userptr_fail_find_vma;
 282         }
 283
 284         if (vma_is_io(buf->vma)) {
 285                 for (num_pages_from_user = 0;
 286                      num_pages_from_user < buf->num_pages;
 287                      ++num_pages_from_user, vaddr += PAGE_SIZE) {
 288                         unsigned long pfn;
 289
 290                         if (follow_pfn(vma, vaddr, &pfn)) {
 291                                 dprintk(1, "no page for address %lu\n", vaddr);
 292                                 break;
 293                         }
 294                         buf->pages[num_pages_from_user] = pfn_to_page(pfn);
 295                 }
 296         } else
 297                 num_pages_from_user = get_user_pages(current, current->mm,
 298                                              vaddr & PAGE_MASK,
 299                                              buf->num_pages,
 300                                              buf->dma_dir == DMA_FROM_DEVICE,
 301                                              1, /* force */
 302                                              buf->pages,
 303                                              NULL);
 304
 305         if (num_pages_from_user != buf->num_pages)
 306                 goto userptr_fail_get_user_pages;
 307
 308         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 309                         buf->num_pages, buf->offset, size, 0))
 310                 goto userptr_fail_alloc_table_from_pages;
 311
 312         sgt = &buf->sg_table;
 313         /*
 314          * No need to sync to the device, this will happen later when the
 315          * prepare() memop is called.
 316          */
 317         if (dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->nents,
 318                              buf->dma_dir, &attrs) == 0)
 319                 goto userptr_fail_map;
 320         return buf;
 321
 322 userptr_fail_map:
 323         sg_free_table(&buf->sg_table);
 324 userptr_fail_alloc_table_from_pages:
 325 userptr_fail_get_user_pages:
 326         dprintk(1, "get_user_pages requested/got: %d/%d]\n",
 327                 buf->num_pages, num_pages_from_user);
 328         if (!vma_is_io(buf->vma))
 329                 while (--num_pages_from_user >= 0)
 330                         put_page(buf->pages[num_pages_from_user]);
 331         vb2_put_vma(buf->vma);
 332 userptr_fail_find_vma:
 333         kfree(buf->pages);
 334 userptr_fail_alloc_pages:
 335         kfree(buf);
 336         return NULL;
 337 }
 338
 339 /*
 340  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 341  *               be used
 342  */
 343 static void vb2_dma_sg_put_userptr(void *buf_priv)
 344 {
 345         struct vb2_dma_sg_buf *buf = buf_priv;
 346         struct sg_table *sgt = &buf->sg_table;
 347         int i = buf->num_pages;
 348         DEFINE_DMA_ATTRS(attrs);
 349
 350         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 351
 352         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 353                __func__, buf->num_pages);
 354         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir, &attrs);
 355         if (buf->vaddr)
 356                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 357         sg_free_table(buf->dma_sgt);
 358         while (--i >= 0) {
 359                 if (buf->dma_dir == DMA_FROM_DEVICE)
 360                         set_page_dirty_lock(buf->pages[i]);
 361                 if (!vma_is_io(buf->vma))
 362                         put_page(buf->pages[i]);
 363         }
 364         kfree(buf->pages);
 365         vb2_put_vma(buf->vma);
 366         kfree(buf);
 367 }
 368
 369 static void *vb2_dma_sg_vaddr(void *buf_priv)
 370 {
 371         struct vb2_dma_sg_buf *buf = buf_priv;
 372
 373         BUG_ON(!buf);
 374
 375         if (!buf->vaddr) {
 376                 if (buf->db_attach)
 377                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 378                 else
 379                         buf->vaddr = vm_map_ram(buf->pages,
 380                                         buf->num_pages, -1, PAGE_KERNEL);
 381         }
 382
 383         /* add offset in case userptr is not page-aligned */
 384         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 385 }
 386
 387 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 388 {
 389         struct vb2_dma_sg_buf *buf = buf_priv;
 390
 391         return atomic_read(&buf->refcount);
 392 }
 393
 394 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 395 {
 396         struct vb2_dma_sg_buf *buf = buf_priv;
 397         unsigned long uaddr = vma->vm_start;
 398         unsigned long usize = vma->vm_end - vma->vm_start;
 399         int i = 0;
 400
 401         if (!buf) {
 402                 printk(KERN_ERR "No memory to map\n");
 403                 return -EINVAL;
 404         }
 405
 406         do {
 407                 int ret;
 408
 409                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 410                 if (ret) {
 411                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 412                         return ret;
 413                 }
 414
 415                 uaddr += PAGE_SIZE;
 416                 usize -= PAGE_SIZE;
 417         } while (usize > 0);
 418
 419
 420         /*
 421          * Use common vm_area operations to track buffer refcount.
 422          */
 423         vma->vm_private_data    = &buf->handler;
 424         vma->vm_ops             = &vb2_common_vm_ops;
 425
 426         vma->vm_ops->open(vma);
 427
 428         return 0;
 429 }
 430
 431 /*********************************************/
 432 /*         DMABUF ops for exporters          */
 433 /*********************************************/
 434
 435 struct vb2_dma_sg_attachment {
 436         struct sg_table sgt;
 437         enum dma_data_direction dma_dir;
 438 };
 439
 440 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 441         struct dma_buf_attachment *dbuf_attach)
 442 {
 443         struct vb2_dma_sg_attachment *attach;
 444         unsigned int i;
 445         struct scatterlist *rd, *wr;
 446         struct sg_table *sgt;
 447         struct vb2_dma_sg_buf *buf = dbuf->priv;
 448         int ret;
 449
 450         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 451         if (!attach)
 452                 return -ENOMEM;
 453
 454         sgt = &attach->sgt;
 455         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 456          * map the same scatter list to multiple attachments at the same time.
 457          */
 458         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 459         if (ret) {
 460                 kfree(attach);
 461                 return -ENOMEM;
 462         }
 463
 464         rd = buf->dma_sgt->sgl;
 465         wr = sgt->sgl;
 466         for (i = 0; i < sgt->orig_nents; ++i) {
 467                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 468                 rd = sg_next(rd);
 469                 wr = sg_next(wr);
 470         }
 471
 472         attach->dma_dir = DMA_NONE;
 473         dbuf_attach->priv = attach;
 474
 475         return 0;
 476 }
 477
 478 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 479         struct dma_buf_attachment *db_attach)
 480 {
 481         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 482         struct sg_table *sgt;
 483
 484         if (!attach)
 485                 return;
 486
 487         sgt = &attach->sgt;
 488
 489         /* release the scatterlist cache */
 490         if (attach->dma_dir != DMA_NONE)
 491                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 492                         attach->dma_dir);
 493         sg_free_table(sgt);
 494         kfree(attach);
 495         db_attach->priv = NULL;
 496 }
 497
 498 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 499         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 500 {
 501         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 502         /* stealing dmabuf mutex to serialize map/unmap operations */
 503         struct mutex *lock = &db_attach->dmabuf->lock;
 504         struct sg_table *sgt;
 505         int ret;
 506
 507         mutex_lock(lock);
 508
 509         sgt = &attach->sgt;
 510         /* return previously mapped sg table */
 511         if (attach->dma_dir == dma_dir) {
 512                 mutex_unlock(lock);
 513                 return sgt;
 514         }
 515
 516         /* release any previous cache */
 517         if (attach->dma_dir != DMA_NONE) {
 518                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 519                         attach->dma_dir);
 520                 attach->dma_dir = DMA_NONE;
 521         }
 522
 523         /* mapping to the client with new direction */
 524         ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dma_dir);
 525         if (ret <= 0) {
 526                 pr_err("failed to map scatterlist\n");
 527                 mutex_unlock(lock);
 528                 return ERR_PTR(-EIO);
 529         }
 530
 531         attach->dma_dir = dma_dir;
 532
 533         mutex_unlock(lock);
 534
 535         return sgt;
 536 }
 537
 538 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 539         struct sg_table *sgt, enum dma_data_direction dma_dir)
 540 {
 541         /* nothing to be done here */
 542 }
 543
 544 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 545 {
 546         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 547         vb2_dma_sg_put(dbuf->priv);
 548 }
 549
 550 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 551 {
 552         struct vb2_dma_sg_buf *buf = dbuf->priv;
 553
 554         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 555 }
 556
 557 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 558 {
 559         struct vb2_dma_sg_buf *buf = dbuf->priv;
 560
 561         return vb2_dma_sg_vaddr(buf);
 562 }
 563
 564 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 565         struct vm_area_struct *vma)
 566 {
 567         return vb2_dma_sg_mmap(dbuf->priv, vma);
 568 }
 569
 570 static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 571         .attach = vb2_dma_sg_dmabuf_ops_attach,
 572         .detach = vb2_dma_sg_dmabuf_ops_detach,
 573         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 574         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 575         .kmap = vb2_dma_sg_dmabuf_ops_kmap,
 576         .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
 577         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 578         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 579         .release = vb2_dma_sg_dmabuf_ops_release,
 580 };
 581
 582 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 583 {
 584         struct vb2_dma_sg_buf *buf = buf_priv;
 585         struct dma_buf *dbuf;
 586         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 587
 588         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 589         exp_info.size = buf->size;
 590         exp_info.flags = flags;
 591         exp_info.priv = buf;
 592
 593         if (WARN_ON(!buf->dma_sgt))
 594                 return NULL;
 595
 596         dbuf = dma_buf_export(&exp_info);
 597         if (IS_ERR(dbuf))
 598                 return NULL;
 599
 600         /* dmabuf keeps reference to vb2 buffer */
 601         atomic_inc(&buf->refcount);
 602
 603         return dbuf;
 604 }
 605
 606 /*********************************************/
 607 /*       callbacks for DMABUF buffers        */
 608 /*********************************************/
 609
 610 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 611 {
 612         struct vb2_dma_sg_buf *buf = mem_priv;
 613         struct sg_table *sgt;
 614
 615         if (WARN_ON(!buf->db_attach)) {
 616                 pr_err("trying to pin a non attached buffer\n");
 617                 return -EINVAL;
 618         }
 619
 620         if (WARN_ON(buf->dma_sgt)) {
 621                 pr_err("dmabuf buffer is already pinned\n");
 622                 return 0;
 623         }
 624
 625         /* get the associated scatterlist for this buffer */
 626         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 627         if (IS_ERR(sgt)) {
 628                 pr_err("Error getting dmabuf scatterlist\n");
 629                 return -EINVAL;
 630         }
 631
 632         buf->dma_sgt = sgt;
 633         buf->vaddr = NULL;
 634
 635         return 0;
 636 }
 637
 638 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 639 {
 640         struct vb2_dma_sg_buf *buf = mem_priv;
 641         struct sg_table *sgt = buf->dma_sgt;
 642
 643         if (WARN_ON(!buf->db_attach)) {
 644                 pr_err("trying to unpin a not attached buffer\n");
 645                 return;
 646         }
 647
 648         if (WARN_ON(!sgt)) {
 649                 pr_err("dmabuf buffer is already unpinned\n");
 650                 return;
 651         }
 652
 653         if (buf->vaddr) {
 654                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 655                 buf->vaddr = NULL;
 656         }
 657         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 658
 659         buf->dma_sgt = NULL;
 660 }
 661
 662 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 663 {
 664         struct vb2_dma_sg_buf *buf = mem_priv;
 665
 666         /* if vb2 works correctly you should never detach mapped buffer */
 667         if (WARN_ON(buf->dma_sgt))
 668                 vb2_dma_sg_unmap_dmabuf(buf);
 669
 670         /* detach this attachment */
 671         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 672         kfree(buf);
 673 }
 674
 675 static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 676         unsigned long size, enum dma_data_direction dma_dir)
 677 {
 678         struct vb2_dma_sg_conf *conf = alloc_ctx;
 679         struct vb2_dma_sg_buf *buf;
 680         struct dma_buf_attachment *dba;
 681
 682         if (dbuf->size < size)
 683                 return ERR_PTR(-EFAULT);
 684
 685         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 686         if (!buf)
 687                 return ERR_PTR(-ENOMEM);
 688
 689         buf->dev = conf->dev;
 690         /* create attachment for the dmabuf with the user device */
 691         dba = dma_buf_attach(dbuf, buf->dev);
 692         if (IS_ERR(dba)) {
 693                 pr_err("failed to attach dmabuf\n");
 694                 kfree(buf);
 695                 return dba;
 696         }
 697
 698         buf->dma_dir = dma_dir;
 699         buf->size = size;
 700         buf->db_attach = dba;
 701
 702         return buf;
 703 }
 704
 705 static void *vb2_dma_sg_cookie(void *buf_priv)
 706 {
 707         struct vb2_dma_sg_buf *buf = buf_priv;
 708
 709         return buf->dma_sgt;
 710 }
 711
 712 const struct vb2_mem_ops vb2_dma_sg_memops = {
 713         .alloc          = vb2_dma_sg_alloc,
 714         .put            = vb2_dma_sg_put,
 715         .get_userptr    = vb2_dma_sg_get_userptr,
 716         .put_userptr    = vb2_dma_sg_put_userptr,
 717         .prepare        = vb2_dma_sg_prepare,
 718         .finish         = vb2_dma_sg_finish,
 719         .vaddr          = vb2_dma_sg_vaddr,
 720         .mmap           = vb2_dma_sg_mmap,
 721         .num_users      = vb2_dma_sg_num_users,
 722         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 723         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 724         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 725         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 726         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 727         .cookie         = vb2_dma_sg_cookie,
 728 };
 729 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 730
 731 void *vb2_dma_sg_init_ctx(struct device *dev)
 732 {
 733         struct vb2_dma_sg_conf *conf;
 734
 735         conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 736         if (!conf)
 737                 return ERR_PTR(-ENOMEM);
 738
 739         conf->dev = dev;
 740
 741         return conf;
 742 }
 743 EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
 744
 745 void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
 746 {
 747         if (!IS_ERR_OR_NULL(alloc_ctx))
 748                 kfree(alloc_ctx);
 749 }
 750 EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
 751
 752 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 753 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 754 MODULE_LICENSE("GPL");