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         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 151                                       buf->dma_dir, &attrs);
 152         if (!sgt->nents)
 153                 goto fail_map;
 154
 155         buf->handler.refcount = &buf->refcount;
 156         buf->handler.put = vb2_dma_sg_put;
 157         buf->handler.arg = buf;
 158
 159         atomic_inc(&buf->refcount);
 160
 161         dprintk(1, "%s: Allocated buffer of %d pages\n",
 162                 __func__, buf->num_pages);
 163         return buf;
 164
 165 fail_map:
 166         put_device(buf->dev);
 167         sg_free_table(buf->dma_sgt);
 168 fail_table_alloc:
 169         num_pages = buf->num_pages;
 170         while (num_pages--)
 171                 __free_page(buf->pages[num_pages]);
 172 fail_pages_alloc:
 173         kfree(buf->pages);
 174 fail_pages_array_alloc:
 175         kfree(buf);
 176         return NULL;
 177 }
 178
 179 static void vb2_dma_sg_put(void *buf_priv)
 180 {
 181         struct vb2_dma_sg_buf *buf = buf_priv;
 182         struct sg_table *sgt = &buf->sg_table;
 183         int i = buf->num_pages;
 184
 185         if (atomic_dec_and_test(&buf->refcount)) {
 186                 DEFINE_DMA_ATTRS(attrs);
 187
 188                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 189                 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 190                         buf->num_pages);
 191                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 192                                    buf->dma_dir, &attrs);
 193                 if (buf->vaddr)
 194                         vm_unmap_ram(buf->vaddr, buf->num_pages);
 195                 sg_free_table(buf->dma_sgt);
 196                 while (--i >= 0)
 197                         __free_page(buf->pages[i]);
 198                 kfree(buf->pages);
 199                 put_device(buf->dev);
 200                 kfree(buf);
 201         }
 202 }
 203
 204 static void vb2_dma_sg_prepare(void *buf_priv)
 205 {
 206         struct vb2_dma_sg_buf *buf = buf_priv;
 207         struct sg_table *sgt = buf->dma_sgt;
 208
 209         /* DMABUF exporter will flush the cache for us */
 210         if (buf->db_attach)
 211                 return;
 212
 213         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 214 }
 215
 216 static void vb2_dma_sg_finish(void *buf_priv)
 217 {
 218         struct vb2_dma_sg_buf *buf = buf_priv;
 219         struct sg_table *sgt = buf->dma_sgt;
 220
 221         /* DMABUF exporter will flush the cache for us */
 222         if (buf->db_attach)
 223                 return;
 224
 225         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 226 }
 227
 228 static inline int vma_is_io(struct vm_area_struct *vma)
 229 {
 230         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 231 }
 232
 233 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 234                                     unsigned long size,
 235                                     enum dma_data_direction dma_dir)
 236 {
 237         struct vb2_dma_sg_conf *conf = alloc_ctx;
 238         struct vb2_dma_sg_buf *buf;
 239         unsigned long first, last;
 240         int num_pages_from_user;
 241         struct vm_area_struct *vma;
 242         struct sg_table *sgt;
 243         DEFINE_DMA_ATTRS(attrs);
 244
 245         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 246
 247         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 248         if (!buf)
 249                 return NULL;
 250
 251         buf->vaddr = NULL;
 252         buf->dev = conf->dev;
 253         buf->dma_dir = dma_dir;
 254         buf->offset = vaddr & ~PAGE_MASK;
 255         buf->size = size;
 256         buf->dma_sgt = &buf->sg_table;
 257
 258         first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
 259         last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
 260         buf->num_pages = last - first + 1;
 261
 262         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 263                              GFP_KERNEL);
 264         if (!buf->pages)
 265                 goto userptr_fail_alloc_pages;
 266
 267         down_read(&current->mm->mmap_sem);
 268         vma = find_vma(current->mm, vaddr);
 269         if (!vma) {
 270                 dprintk(1, "no vma for address %lu\n", vaddr);
 271                 goto userptr_fail_find_vma;
 272         }
 273
 274         if (vma->vm_end < vaddr + size) {
 275                 dprintk(1, "vma at %lu is too small for %lu bytes\n",
 276                         vaddr, size);
 277                 goto userptr_fail_find_vma;
 278         }
 279
 280         buf->vma = vb2_get_vma(vma);
 281         if (!buf->vma) {
 282                 dprintk(1, "failed to copy vma\n");
 283                 goto userptr_fail_find_vma;
 284         }
 285
 286         if (vma_is_io(buf->vma)) {
 287                 for (num_pages_from_user = 0;
 288                      num_pages_from_user < buf->num_pages;
 289                      ++num_pages_from_user, vaddr += PAGE_SIZE) {
 290                         unsigned long pfn;
 291
 292                         if (follow_pfn(vma, vaddr, &pfn)) {
 293                                 dprintk(1, "no page for address %lu\n", vaddr);
 294                                 break;
 295                         }
 296                         buf->pages[num_pages_from_user] = pfn_to_page(pfn);
 297                 }
 298         } else
 299                 num_pages_from_user = get_user_pages(current, current->mm,
 300                                              vaddr & PAGE_MASK,
 301                                              buf->num_pages,
 302                                              buf->dma_dir == DMA_FROM_DEVICE,
 303                                              1, /* force */
 304                                              buf->pages,
 305                                              NULL);
 306         up_read(&current->mm->mmap_sem);
 307
 308         if (num_pages_from_user != buf->num_pages)
 309                 goto userptr_fail_get_user_pages;
 310
 311         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 312                         buf->num_pages, buf->offset, size, 0))
 313                 goto userptr_fail_alloc_table_from_pages;
 314
 315         sgt = &buf->sg_table;
 316         /*
 317          * No need to sync to the device, this will happen later when the
 318          * prepare() memop is called.
 319          */
 320         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 321                                       buf->dma_dir, &attrs);
 322         if (!sgt->nents)
 323                 goto userptr_fail_map;
 324
 325         return buf;
 326
 327 userptr_fail_map:
 328         sg_free_table(&buf->sg_table);
 329 userptr_fail_alloc_table_from_pages:
 330 userptr_fail_get_user_pages:
 331         dprintk(1, "get_user_pages requested/got: %d/%d]\n",
 332                 buf->num_pages, num_pages_from_user);
 333         if (!vma_is_io(buf->vma))
 334                 while (--num_pages_from_user >= 0)
 335                         put_page(buf->pages[num_pages_from_user]);
 336         down_read(&current->mm->mmap_sem);
 337         vb2_put_vma(buf->vma);
 338 userptr_fail_find_vma:
 339         up_read(&current->mm->mmap_sem);
 340         kfree(buf->pages);
 341 userptr_fail_alloc_pages:
 342         kfree(buf);
 343         return NULL;
 344 }
 345
 346 /*
 347  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 348  *               be used
 349  */
 350 static void vb2_dma_sg_put_userptr(void *buf_priv)
 351 {
 352         struct vb2_dma_sg_buf *buf = buf_priv;
 353         struct sg_table *sgt = &buf->sg_table;
 354         int i = buf->num_pages;
 355         DEFINE_DMA_ATTRS(attrs);
 356
 357         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 358
 359         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 360                __func__, buf->num_pages);
 361         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir,
 362                            &attrs);
 363         if (buf->vaddr)
 364                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 365         sg_free_table(buf->dma_sgt);
 366         while (--i >= 0) {
 367                 if (buf->dma_dir == DMA_FROM_DEVICE)
 368                         set_page_dirty_lock(buf->pages[i]);
 369                 if (!vma_is_io(buf->vma))
 370                         put_page(buf->pages[i]);
 371         }
 372         kfree(buf->pages);
 373         down_read(&current->mm->mmap_sem);
 374         vb2_put_vma(buf->vma);
 375         up_read(&current->mm->mmap_sem);
 376         kfree(buf);
 377 }
 378
 379 static void *vb2_dma_sg_vaddr(void *buf_priv)
 380 {
 381         struct vb2_dma_sg_buf *buf = buf_priv;
 382
 383         BUG_ON(!buf);
 384
 385         if (!buf->vaddr) {
 386                 if (buf->db_attach)
 387                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 388                 else
 389                         buf->vaddr = vm_map_ram(buf->pages,
 390                                         buf->num_pages, -1, PAGE_KERNEL);
 391         }
 392
 393         /* add offset in case userptr is not page-aligned */
 394         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 395 }
 396
 397 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 398 {
 399         struct vb2_dma_sg_buf *buf = buf_priv;
 400
 401         return atomic_read(&buf->refcount);
 402 }
 403
 404 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 405 {
 406         struct vb2_dma_sg_buf *buf = buf_priv;
 407         unsigned long uaddr = vma->vm_start;
 408         unsigned long usize = vma->vm_end - vma->vm_start;
 409         int i = 0;
 410
 411         if (!buf) {
 412                 printk(KERN_ERR "No memory to map\n");
 413                 return -EINVAL;
 414         }
 415
 416         do {
 417                 int ret;
 418
 419                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 420                 if (ret) {
 421                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 422                         return ret;
 423                 }
 424
 425                 uaddr += PAGE_SIZE;
 426                 usize -= PAGE_SIZE;
 427         } while (usize > 0);
 428
 429
 430         /*
 431          * Use common vm_area operations to track buffer refcount.
 432          */
 433         vma->vm_private_data    = &buf->handler;
 434         vma->vm_ops             = &vb2_common_vm_ops;
 435
 436         vma->vm_ops->open(vma);
 437
 438         return 0;
 439 }
 440
 441 /*********************************************/
 442 /*         DMABUF ops for exporters          */
 443 /*********************************************/
 444
 445 struct vb2_dma_sg_attachment {
 446         struct sg_table sgt;
 447         enum dma_data_direction dma_dir;
 448 };
 449
 450 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 451         struct dma_buf_attachment *dbuf_attach)
 452 {
 453         struct vb2_dma_sg_attachment *attach;
 454         unsigned int i;
 455         struct scatterlist *rd, *wr;
 456         struct sg_table *sgt;
 457         struct vb2_dma_sg_buf *buf = dbuf->priv;
 458         int ret;
 459
 460         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 461         if (!attach)
 462                 return -ENOMEM;
 463
 464         sgt = &attach->sgt;
 465         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 466          * map the same scatter list to multiple attachments at the same time.
 467          */
 468         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 469         if (ret) {
 470                 kfree(attach);
 471                 return -ENOMEM;
 472         }
 473
 474         rd = buf->dma_sgt->sgl;
 475         wr = sgt->sgl;
 476         for (i = 0; i < sgt->orig_nents; ++i) {
 477                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 478                 rd = sg_next(rd);
 479                 wr = sg_next(wr);
 480         }
 481
 482         attach->dma_dir = DMA_NONE;
 483         dbuf_attach->priv = attach;
 484
 485         return 0;
 486 }
 487
 488 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 489         struct dma_buf_attachment *db_attach)
 490 {
 491         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 492         struct sg_table *sgt;
 493
 494         if (!attach)
 495                 return;
 496
 497         sgt = &attach->sgt;
 498
 499         /* release the scatterlist cache */
 500         if (attach->dma_dir != DMA_NONE)
 501                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 502                         attach->dma_dir);
 503         sg_free_table(sgt);
 504         kfree(attach);
 505         db_attach->priv = NULL;
 506 }
 507
 508 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 509         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 510 {
 511         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 512         /* stealing dmabuf mutex to serialize map/unmap operations */
 513         struct mutex *lock = &db_attach->dmabuf->lock;
 514         struct sg_table *sgt;
 515
 516         mutex_lock(lock);
 517
 518         sgt = &attach->sgt;
 519         /* return previously mapped sg table */
 520         if (attach->dma_dir == dma_dir) {
 521                 mutex_unlock(lock);
 522                 return sgt;
 523         }
 524
 525         /* release any previous cache */
 526         if (attach->dma_dir != DMA_NONE) {
 527                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 528                         attach->dma_dir);
 529                 attach->dma_dir = DMA_NONE;
 530         }
 531
 532         /* mapping to the client with new direction */
 533         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 534                                 dma_dir);
 535         if (!sgt->nents) {
 536                 pr_err("failed to map scatterlist\n");
 537                 mutex_unlock(lock);
 538                 return ERR_PTR(-EIO);
 539         }
 540
 541         attach->dma_dir = dma_dir;
 542
 543         mutex_unlock(lock);
 544
 545         return sgt;
 546 }
 547
 548 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 549         struct sg_table *sgt, enum dma_data_direction dma_dir)
 550 {
 551         /* nothing to be done here */
 552 }
 553
 554 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 555 {
 556         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 557         vb2_dma_sg_put(dbuf->priv);
 558 }
 559
 560 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 561 {
 562         struct vb2_dma_sg_buf *buf = dbuf->priv;
 563
 564         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 565 }
 566
 567 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 568 {
 569         struct vb2_dma_sg_buf *buf = dbuf->priv;
 570
 571         return vb2_dma_sg_vaddr(buf);
 572 }
 573
 574 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 575         struct vm_area_struct *vma)
 576 {
 577         return vb2_dma_sg_mmap(dbuf->priv, vma);
 578 }
 579
 580 static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 581         .attach = vb2_dma_sg_dmabuf_ops_attach,
 582         .detach = vb2_dma_sg_dmabuf_ops_detach,
 583         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 584         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 585         .kmap = vb2_dma_sg_dmabuf_ops_kmap,
 586         .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
 587         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 588         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 589         .release = vb2_dma_sg_dmabuf_ops_release,
 590 };
 591
 592 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 593 {
 594         struct vb2_dma_sg_buf *buf = buf_priv;
 595         struct dma_buf *dbuf;
 596         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 597
 598         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 599         exp_info.size = buf->size;
 600         exp_info.flags = flags;
 601         exp_info.priv = buf;
 602
 603         if (WARN_ON(!buf->dma_sgt))
 604                 return NULL;
 605
 606         dbuf = dma_buf_export(&exp_info);
 607         if (IS_ERR(dbuf))
 608                 return NULL;
 609
 610         /* dmabuf keeps reference to vb2 buffer */
 611         atomic_inc(&buf->refcount);
 612
 613         return dbuf;
 614 }
 615
 616 /*********************************************/
 617 /*       callbacks for DMABUF buffers        */
 618 /*********************************************/
 619
 620 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 621 {
 622         struct vb2_dma_sg_buf *buf = mem_priv;
 623         struct sg_table *sgt;
 624
 625         if (WARN_ON(!buf->db_attach)) {
 626                 pr_err("trying to pin a non attached buffer\n");
 627                 return -EINVAL;
 628         }
 629
 630         if (WARN_ON(buf->dma_sgt)) {
 631                 pr_err("dmabuf buffer is already pinned\n");
 632                 return 0;
 633         }
 634
 635         /* get the associated scatterlist for this buffer */
 636         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 637         if (IS_ERR(sgt)) {
 638                 pr_err("Error getting dmabuf scatterlist\n");
 639                 return -EINVAL;
 640         }
 641
 642         buf->dma_sgt = sgt;
 643         buf->vaddr = NULL;
 644
 645         return 0;
 646 }
 647
 648 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 649 {
 650         struct vb2_dma_sg_buf *buf = mem_priv;
 651         struct sg_table *sgt = buf->dma_sgt;
 652
 653         if (WARN_ON(!buf->db_attach)) {
 654                 pr_err("trying to unpin a not attached buffer\n");
 655                 return;
 656         }
 657
 658         if (WARN_ON(!sgt)) {
 659                 pr_err("dmabuf buffer is already unpinned\n");
 660                 return;
 661         }
 662
 663         if (buf->vaddr) {
 664                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 665                 buf->vaddr = NULL;
 666         }
 667         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 668
 669         buf->dma_sgt = NULL;
 670 }
 671
 672 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 673 {
 674         struct vb2_dma_sg_buf *buf = mem_priv;
 675
 676         /* if vb2 works correctly you should never detach mapped buffer */
 677         if (WARN_ON(buf->dma_sgt))
 678                 vb2_dma_sg_unmap_dmabuf(buf);
 679
 680         /* detach this attachment */
 681         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 682         kfree(buf);
 683 }
 684
 685 static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 686         unsigned long size, enum dma_data_direction dma_dir)
 687 {
 688         struct vb2_dma_sg_conf *conf = alloc_ctx;
 689         struct vb2_dma_sg_buf *buf;
 690         struct dma_buf_attachment *dba;
 691
 692         if (dbuf->size < size)
 693                 return ERR_PTR(-EFAULT);
 694
 695         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 696         if (!buf)
 697                 return ERR_PTR(-ENOMEM);
 698
 699         buf->dev = conf->dev;
 700         /* create attachment for the dmabuf with the user device */
 701         dba = dma_buf_attach(dbuf, buf->dev);
 702         if (IS_ERR(dba)) {
 703                 pr_err("failed to attach dmabuf\n");
 704                 kfree(buf);
 705                 return dba;
 706         }
 707
 708         buf->dma_dir = dma_dir;
 709         buf->size = size;
 710         buf->db_attach = dba;
 711
 712         return buf;
 713 }
 714
 715 static void *vb2_dma_sg_cookie(void *buf_priv)
 716 {
 717         struct vb2_dma_sg_buf *buf = buf_priv;
 718
 719         return buf->dma_sgt;
 720 }
 721
 722 const struct vb2_mem_ops vb2_dma_sg_memops = {
 723         .alloc          = vb2_dma_sg_alloc,
 724         .put            = vb2_dma_sg_put,
 725         .get_userptr    = vb2_dma_sg_get_userptr,
 726         .put_userptr    = vb2_dma_sg_put_userptr,
 727         .prepare        = vb2_dma_sg_prepare,
 728         .finish         = vb2_dma_sg_finish,
 729         .vaddr          = vb2_dma_sg_vaddr,
 730         .mmap           = vb2_dma_sg_mmap,
 731         .num_users      = vb2_dma_sg_num_users,
 732         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 733         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 734         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 735         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 736         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 737         .cookie         = vb2_dma_sg_cookie,
 738 };
 739 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 740
 741 void *vb2_dma_sg_init_ctx(struct device *dev)
 742 {
 743         struct vb2_dma_sg_conf *conf;
 744
 745         conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 746         if (!conf)
 747                 return ERR_PTR(-ENOMEM);
 748
 749         conf->dev = dev;
 750
 751         return conf;
 752 }
 753 EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
 754
 755 void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
 756 {
 757         if (!IS_ERR_OR_NULL(alloc_ctx))
 758                 kfree(alloc_ctx);
 759 }
 760 EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
 761
 762 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 763 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 764 MODULE_LICENSE("GPL");