drivers/media/video/videobuf-dma-sg.c

   1 /*
   2  * helper functions for SG DMA video4linux capture buffers
   3  *
   4  * The functions expect the hardware being able to scatter gather
   5  * (i.e. the buffers are not linear in physical memory, but fragmented
   6  * into PAGE_SIZE chunks).  They also assume the driver does not need
   7  * to touch the video data.
   8  *
   9  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
  10  *
  11  * Highly based on video-buf written originally by:
  12  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
  13  * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
  14  * (c) 2006 Ted Walther and John Sokol
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2
  19  */
  20
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26 #include <linux/interrupt.h>
  27
  28 #include <linux/dma-mapping.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/scatterlist.h>
  32 #include <asm/page.h>
  33 #include <asm/pgtable.h>
  34
  35 #include <media/videobuf-dma-sg.h>
  36
  37 #define MAGIC_DMABUF 0x19721112
  38 #define MAGIC_SG_MEM 0x17890714
  39
  40 #define MAGIC_CHECK(is, should)                                         \
  41         if (unlikely((is) != (should))) {                               \
  42                 printk(KERN_ERR "magic mismatch: %x (expected %x)\n",   \
  43                                 is, should);                            \
  44                 BUG();                                                  \
  45         }
  46
  47 static int debug;
  48 module_param(debug, int, 0644);
  49
  50 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
  51 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  52 MODULE_LICENSE("GPL");
  53
  54 #define dprintk(level, fmt, arg...)                                     \
  55         if (debug >= level)                                             \
  56                 printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
  57
  58 /* --------------------------------------------------------------------- */
  59
  60 struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
  61 {
  62         struct scatterlist *sglist;
  63         struct page *pg;
  64         int i;
  65
  66         sglist = vmalloc(nr_pages * sizeof(*sglist));
  67         if (NULL == sglist)
  68                 return NULL;
  69         memset(sglist, 0, nr_pages * sizeof(*sglist));
  70         sg_init_table(sglist, nr_pages);
  71         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  72                 pg = vmalloc_to_page(virt);
  73                 if (NULL == pg)
  74                         goto err;
  75                 BUG_ON(PageHighMem(pg));
  76                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  77         }
  78         return sglist;
  79
  80 err:
  81         vfree(sglist);
  82         return NULL;
  83 }
  84 EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
  85
  86 struct scatterlist *videobuf_pages_to_sg(struct page **pages, int nr_pages,
  87                                          int offset)
  88 {
  89         struct scatterlist *sglist;
  90         int i;
  91
  92         if (NULL == pages[0])
  93                 return NULL;
  94         sglist = vmalloc(nr_pages * sizeof(*sglist));
  95         if (NULL == sglist)
  96                 return NULL;
  97         sg_init_table(sglist, nr_pages);
  98
  99         if (PageHighMem(pages[0]))
 100                 /* DMA to highmem pages might not work */
 101                 goto highmem;
 102         sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
 103         for (i = 1; i < nr_pages; i++) {
 104                 if (NULL == pages[i])
 105                         goto nopage;
 106                 if (PageHighMem(pages[i]))
 107                         goto highmem;
 108                 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
 109         }
 110         return sglist;
 111
 112 nopage:
 113         dprintk(2, "sgl: oops - no page\n");
 114         vfree(sglist);
 115         return NULL;
 116
 117 highmem:
 118         dprintk(2, "sgl: oops - highmem page\n");
 119         vfree(sglist);
 120         return NULL;
 121 }
 122
 123 /* --------------------------------------------------------------------- */
 124
 125 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
 126 {
 127         struct videobuf_dma_sg_memory *mem = buf->priv;
 128         BUG_ON(!mem);
 129
 130         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 131
 132         return &mem->dma;
 133 }
 134 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 135
 136 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 137 {
 138         memset(dma, 0, sizeof(*dma));
 139         dma->magic = MAGIC_DMABUF;
 140 }
 141 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 142
 143 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 144                         int direction, unsigned long data, unsigned long size)
 145 {
 146         unsigned long first, last;
 147         int err, rw = 0;
 148
 149         dma->direction = direction;
 150         switch (dma->direction) {
 151         case DMA_FROM_DEVICE:
 152                 rw = READ;
 153                 break;
 154         case DMA_TO_DEVICE:
 155                 rw = WRITE;
 156                 break;
 157         default:
 158                 BUG();
 159         }
 160
 161         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 162         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 163         dma->offset   = data & ~PAGE_MASK;
 164         dma->nr_pages = last-first+1;
 165         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
 166         if (NULL == dma->pages)
 167                 return -ENOMEM;
 168
 169         dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
 170                 data, size, dma->nr_pages);
 171
 172         err = get_user_pages(current, current->mm,
 173                              data & PAGE_MASK, dma->nr_pages,
 174                              rw == READ, 1, /* force */
 175                              dma->pages, NULL);
 176
 177         if (err != dma->nr_pages) {
 178                 dma->nr_pages = (err >= 0) ? err : 0;
 179                 dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
 180                 return err < 0 ? err : -EINVAL;
 181         }
 182         return 0;
 183 }
 184
 185 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 186                            unsigned long data, unsigned long size)
 187 {
 188         int ret;
 189
 190         down_read(&current->mm->mmap_sem);
 191         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 192         up_read(&current->mm->mmap_sem);
 193
 194         return ret;
 195 }
 196 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 197
 198 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 199                              int nr_pages)
 200 {
 201         dprintk(1, "init kernel [%d pages]\n", nr_pages);
 202
 203         dma->direction = direction;
 204         dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
 205         if (NULL == dma->vmalloc) {
 206                 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
 207                 return -ENOMEM;
 208         }
 209
 210         dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
 211                                 (unsigned long)dma->vmalloc,
 212                                 nr_pages << PAGE_SHIFT);
 213
 214         memset(dma->vmalloc, 0, nr_pages << PAGE_SHIFT);
 215         dma->nr_pages = nr_pages;
 216
 217         return 0;
 218 }
 219 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 220
 221 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 222                               dma_addr_t addr, int nr_pages)
 223 {
 224         dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
 225                 nr_pages, (unsigned long)addr);
 226         dma->direction = direction;
 227
 228         if (0 == addr)
 229                 return -EINVAL;
 230
 231         dma->bus_addr = addr;
 232         dma->nr_pages = nr_pages;
 233
 234         return 0;
 235 }
 236 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 237
 238 int videobuf_dma_map(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 239 {
 240         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 241         BUG_ON(0 == dma->nr_pages);
 242
 243         if (dma->pages) {
 244                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 245                                                    dma->offset);
 246         }
 247         if (dma->vmalloc) {
 248                 dma->sglist = videobuf_vmalloc_to_sg(dma->vmalloc,
 249                                                      dma->nr_pages);
 250         }
 251         if (dma->bus_addr) {
 252                 dma->sglist = vmalloc(sizeof(*dma->sglist));
 253                 if (NULL != dma->sglist) {
 254                         dma->sglen = 1;
 255                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr
 256                                                         & PAGE_MASK;
 257                         dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
 258                         sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
 259                 }
 260         }
 261         if (NULL == dma->sglist) {
 262                 dprintk(1, "scatterlist is NULL\n");
 263                 return -ENOMEM;
 264         }
 265         if (!dma->bus_addr) {
 266                 dma->sglen = dma_map_sg(q->dev, dma->sglist,
 267                                         dma->nr_pages, dma->direction);
 268                 if (0 == dma->sglen) {
 269                         printk(KERN_WARNING
 270                                "%s: videobuf_map_sg failed\n", __func__);
 271                         vfree(dma->sglist);
 272                         dma->sglist = NULL;
 273                         dma->sglen = 0;
 274                         return -ENOMEM;
 275                 }
 276         }
 277
 278         return 0;
 279 }
 280 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 281
 282 int videobuf_dma_unmap(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 283 {
 284         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 285
 286         if (!dma->sglen)
 287                 return 0;
 288
 289         dma_unmap_sg(q->dev, dma->sglist, dma->sglen, dma->direction);
 290
 291         vfree(dma->sglist);
 292         dma->sglist = NULL;
 293         dma->sglen = 0;
 294
 295         return 0;
 296 }
 297 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 298
 299 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 300 {
 301         int i;
 302         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 303         BUG_ON(dma->sglen);
 304
 305         if (dma->pages) {
 306                 for (i = 0; i < dma->nr_pages; i++)
 307                         page_cache_release(dma->pages[i]);
 308                 kfree(dma->pages);
 309                 dma->pages = NULL;
 310         }
 311
 312         vfree(dma->vmalloc);
 313         dma->vmalloc = NULL;
 314
 315         if (dma->bus_addr)
 316                 dma->bus_addr = 0;
 317         dma->direction = DMA_NONE;
 318
 319         return 0;
 320 }
 321 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 322
 323 /* --------------------------------------------------------------------- */
 324
 325 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 326 {
 327         struct videobuf_queue q;
 328
 329         q.dev = dev;
 330
 331         return videobuf_dma_map(&q, dma);
 332 }
 333 EXPORT_SYMBOL_GPL(videobuf_sg_dma_map);
 334
 335 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 336 {
 337         struct videobuf_queue q;
 338
 339         q.dev = dev;
 340
 341         return videobuf_dma_unmap(&q, dma);
 342 }
 343 EXPORT_SYMBOL_GPL(videobuf_sg_dma_unmap);
 344
 345 /* --------------------------------------------------------------------- */
 346
 347 static void videobuf_vm_open(struct vm_area_struct *vma)
 348 {
 349         struct videobuf_mapping *map = vma->vm_private_data;
 350
 351         dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
 352                 map->count, vma->vm_start, vma->vm_end);
 353
 354         map->count++;
 355 }
 356
 357 static void videobuf_vm_close(struct vm_area_struct *vma)
 358 {
 359         struct videobuf_mapping *map = vma->vm_private_data;
 360         struct videobuf_queue *q = map->q;
 361         struct videobuf_dma_sg_memory *mem;
 362         int i;
 363
 364         dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
 365                 map->count, vma->vm_start, vma->vm_end);
 366
 367         map->count--;
 368         if (0 == map->count) {
 369                 dprintk(1, "munmap %p q=%p\n", map, q);
 370                 mutex_lock(&q->vb_lock);
 371                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 372                         if (NULL == q->bufs[i])
 373                                 continue;
 374                         mem = q->bufs[i]->priv;
 375                         if (!mem)
 376                                 continue;
 377
 378                         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 379
 380                         if (q->bufs[i]->map != map)
 381                                 continue;
 382                         q->bufs[i]->map   = NULL;
 383                         q->bufs[i]->baddr = 0;
 384                         q->ops->buf_release(q, q->bufs[i]);
 385                 }
 386                 mutex_unlock(&q->vb_lock);
 387                 kfree(map);
 388         }
 389         return;
 390 }
 391
 392 /*
 393  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 394  * memory location with 32bit PCI devices (i.e. don't use highmem for
 395  * now ...).  Bounce buffers don't work very well for the data rates
 396  * video capture has.
 397  */
 398 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 399 {
 400         struct page *page;
 401
 402         dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
 403                 (unsigned long)vmf->virtual_address,
 404                 vma->vm_start, vma->vm_end);
 405
 406         page = alloc_page(GFP_USER | __GFP_DMA32);
 407         if (!page)
 408                 return VM_FAULT_OOM;
 409         clear_user_highpage(page, (unsigned long)vmf->virtual_address);
 410         vmf->page = page;
 411
 412         return 0;
 413 }
 414
 415 static const struct vm_operations_struct videobuf_vm_ops = {
 416         .open   = videobuf_vm_open,
 417         .close  = videobuf_vm_close,
 418         .fault  = videobuf_vm_fault,
 419 };
 420
 421 /* ---------------------------------------------------------------------
 422  * SG handlers for the generic methods
 423  */
 424
 425 /* Allocated area consists on 3 parts:
 426         struct video_buffer
 427         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 428         struct videobuf_dma_sg_memory
 429  */
 430
 431 static struct videobuf_buffer *__videobuf_alloc(size_t size)
 432 {
 433         struct videobuf_dma_sg_memory *mem;
 434         struct videobuf_buffer *vb;
 435
 436         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 437         if (!vb)
 438                 return vb;
 439
 440         mem = vb->priv = ((char *)vb) + size;
 441         mem->magic = MAGIC_SG_MEM;
 442
 443         videobuf_dma_init(&mem->dma);
 444
 445         dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 446                 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 447                 mem, (long)sizeof(*mem));
 448
 449         return vb;
 450 }
 451
 452 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 453 {
 454         struct videobuf_dma_sg_memory *mem = buf->priv;
 455         BUG_ON(!mem);
 456
 457         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 458
 459         return mem->dma.vmalloc;
 460 }
 461
 462 static int __videobuf_iolock(struct videobuf_queue *q,
 463                              struct videobuf_buffer *vb,
 464                              struct v4l2_framebuffer *fbuf)
 465 {
 466         int err, pages;
 467         dma_addr_t bus;
 468         struct videobuf_dma_sg_memory *mem = vb->priv;
 469         BUG_ON(!mem);
 470
 471         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 472
 473         switch (vb->memory) {
 474         case V4L2_MEMORY_MMAP:
 475         case V4L2_MEMORY_USERPTR:
 476                 if (0 == vb->baddr) {
 477                         /* no userspace addr -- kernel bounce buffer */
 478                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 479                         err = videobuf_dma_init_kernel(&mem->dma,
 480                                                        DMA_FROM_DEVICE,
 481                                                        pages);
 482                         if (0 != err)
 483                                 return err;
 484                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 485                         /* dma directly to userspace */
 486                         err = videobuf_dma_init_user(&mem->dma,
 487                                                      DMA_FROM_DEVICE,
 488                                                      vb->baddr, vb->bsize);
 489                         if (0 != err)
 490                                 return err;
 491                 } else {
 492                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 493                         buffers can only be called from videobuf_qbuf
 494                         we take current->mm->mmap_sem there, to prevent
 495                         locking inversion, so don't take it here */
 496
 497                         err = videobuf_dma_init_user_locked(&mem->dma,
 498                                                       DMA_FROM_DEVICE,
 499                                                       vb->baddr, vb->bsize);
 500                         if (0 != err)
 501                                 return err;
 502                 }
 503                 break;
 504         case V4L2_MEMORY_OVERLAY:
 505                 if (NULL == fbuf)
 506                         return -EINVAL;
 507                 /* FIXME: need sanity checks for vb->boff */
 508                 /*
 509                  * Using a double cast to avoid compiler warnings when
 510                  * building for PAE. Compiler doesn't like direct casting
 511                  * of a 32 bit ptr to 64 bit integer.
 512                  */
 513                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 514                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 515                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 516                                                 bus, pages);
 517                 if (0 != err)
 518                         return err;
 519                 break;
 520         default:
 521                 BUG();
 522         }
 523         err = videobuf_dma_map(q, &mem->dma);
 524         if (0 != err)
 525                 return err;
 526
 527         return 0;
 528 }
 529
 530 static int __videobuf_sync(struct videobuf_queue *q,
 531                            struct videobuf_buffer *buf)
 532 {
 533         struct videobuf_dma_sg_memory *mem = buf->priv;
 534         BUG_ON(!mem || !mem->dma.sglen);
 535
 536         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 537         MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
 538
 539         dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
 540                             mem->dma.sglen, mem->dma.direction);
 541
 542         return 0;
 543 }
 544
 545 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 546                                   struct videobuf_buffer *buf,
 547                                   struct vm_area_struct *vma)
 548 {
 549         struct videobuf_dma_sg_memory *mem = buf->priv;
 550         struct videobuf_mapping *map;
 551         unsigned int first, last, size = 0, i;
 552         int retval;
 553
 554         retval = -EINVAL;
 555
 556         /* This function maintains backwards compatibility with V4L1 and will
 557          * map more than one buffer if the vma length is equal to the combined
 558          * size of multiple buffers than it will map them together.  See
 559          * VIDIOCGMBUF in the v4l spec
 560          *
 561          * TODO: Allow drivers to specify if they support this mode
 562          */
 563
 564         BUG_ON(!mem);
 565         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 566
 567         /* look for first buffer to map */
 568         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 569                 if (buf == q->bufs[first]) {
 570                         size = PAGE_ALIGN(q->bufs[first]->bsize);
 571                         break;
 572                 }
 573         }
 574
 575         /* paranoia, should never happen since buf is always valid. */
 576         if (!size) {
 577                 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
 578                                 (vma->vm_pgoff << PAGE_SHIFT));
 579                 goto done;
 580         }
 581
 582         last = first;
 583 #ifdef CONFIG_VIDEO_V4L1_COMPAT
 584         if (size != (vma->vm_end - vma->vm_start)) {
 585                 /* look for last buffer to map */
 586                 for (last = first + 1; last < VIDEO_MAX_FRAME; last++) {
 587                         if (NULL == q->bufs[last])
 588                                 continue;
 589                         if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 590                                 continue;
 591                         if (q->bufs[last]->map) {
 592                                 retval = -EBUSY;
 593                                 goto done;
 594                         }
 595                         size += PAGE_ALIGN(q->bufs[last]->bsize);
 596                         if (size == (vma->vm_end - vma->vm_start))
 597                                 break;
 598                 }
 599                 if (VIDEO_MAX_FRAME == last) {
 600                         dprintk(1, "mmap app bug: size invalid [size=0x%lx]\n",
 601                                         (vma->vm_end - vma->vm_start));
 602                         goto done;
 603                 }
 604         }
 605 #endif
 606
 607         /* create mapping + update buffer list */
 608         retval = -ENOMEM;
 609         map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 610         if (NULL == map)
 611                 goto done;
 612
 613         size = 0;
 614         for (i = first; i <= last; i++) {
 615                 if (NULL == q->bufs[i])
 616                         continue;
 617                 q->bufs[i]->map   = map;
 618                 q->bufs[i]->baddr = vma->vm_start + size;
 619                 size += PAGE_ALIGN(q->bufs[i]->bsize);
 620         }
 621
 622         map->count    = 1;
 623         map->start    = vma->vm_start;
 624         map->end      = vma->vm_end;
 625         map->q        = q;
 626         vma->vm_ops   = &videobuf_vm_ops;
 627         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 628         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 629         vma->vm_private_data = map;
 630         dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 631                 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
 632         retval = 0;
 633
 634 done:
 635         return retval;
 636 }
 637
 638 static struct videobuf_qtype_ops sg_ops = {
 639         .magic        = MAGIC_QTYPE_OPS,
 640
 641         .alloc        = __videobuf_alloc,
 642         .iolock       = __videobuf_iolock,
 643         .sync         = __videobuf_sync,
 644         .mmap_mapper  = __videobuf_mmap_mapper,
 645         .vaddr        = __videobuf_to_vaddr,
 646 };
 647
 648 void *videobuf_sg_alloc(size_t size)
 649 {
 650         struct videobuf_queue q;
 651
 652         /* Required to make generic handler to call __videobuf_alloc */
 653         q.int_ops = &sg_ops;
 654
 655         q.msize = size;
 656
 657         return videobuf_alloc(&q);
 658 }
 659 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 660
 661 void videobuf_queue_sg_init(struct videobuf_queue *q,
 662                          const struct videobuf_queue_ops *ops,
 663                          struct device *dev,
 664                          spinlock_t *irqlock,
 665                          enum v4l2_buf_type type,
 666                          enum v4l2_field field,
 667                          unsigned int msize,
 668                          void *priv)
 669 {
 670         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 671                                  priv, &sg_ops);
 672 }
 673 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 674