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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * helper functions for SG DMA video4linux capture buffers
   4  *
   5  * The functions expect the hardware being able to scatter gather
   6  * (i.e. the buffers are not linear in physical memory, but fragmented
   7  * into PAGE_SIZE chunks).  They also assume the driver does not need
   8  * to touch the video data.
   9  *
  10  * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
  11  *
  12  * Highly based on video-buf written originally by:
  13  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
  14  * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
  15  * (c) 2006 Ted Walther and John Sokol
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/sched/mm.h>
  22 #include <linux/slab.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/pgtable.h>
  25
  26 #include <linux/dma-mapping.h>
  27 #include <linux/vmalloc.h>
  28 #include <linux/pagemap.h>
  29 #include <linux/scatterlist.h>
  30 #include <asm/page.h>
  31
  32 #include <media/videobuf-dma-sg.h>
  33
  34 #define MAGIC_DMABUF 0x19721112
  35 #define MAGIC_SG_MEM 0x17890714
  36
  37 #define MAGIC_CHECK(is, should)                                         \
  38         if (unlikely((is) != (should))) {                               \
  39                 printk(KERN_ERR "magic mismatch: %x (expected %x)\n",   \
  40                                 is, should);                            \
  41                 BUG();                                                  \
  42         }
  43
  44 static int debug;
  45 module_param(debug, int, 0644);
  46
  47 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
  48 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
  49 MODULE_LICENSE("GPL");
  50
  51 #define dprintk(level, fmt, arg...)                                     \
  52         if (debug >= level)                                             \
  53                 printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
  54
  55 /* --------------------------------------------------------------------- */
  56
  57 /*
  58  * Return a scatterlist for some page-aligned vmalloc()'ed memory
  59  * block (NULL on errors).  Memory for the scatterlist is allocated
  60  * using kmalloc.  The caller must free the memory.
  61  */
  62 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
  63                                                   int nr_pages)
  64 {
  65         struct scatterlist *sglist;
  66         struct page *pg;
  67         int i;
  68
  69         sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
  70         if (NULL == sglist)
  71                 return NULL;
  72         sg_init_table(sglist, nr_pages);
  73         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  74                 pg = vmalloc_to_page(virt);
  75                 if (NULL == pg)
  76                         goto err;
  77                 BUG_ON(PageHighMem(pg));
  78                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  79         }
  80         return sglist;
  81
  82 err:
  83         vfree(sglist);
  84         return NULL;
  85 }
  86
  87 /*
  88  * Return a scatterlist for a an array of userpages (NULL on errors).
  89  * Memory for the scatterlist is allocated using kmalloc.  The caller
  90  * must free the memory.
  91  */
  92 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
  93                                         int nr_pages, int offset, size_t size)
  94 {
  95         struct scatterlist *sglist;
  96         int i;
  97
  98         if (NULL == pages[0])
  99                 return NULL;
 100         sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
 101         if (NULL == sglist)
 102                 return NULL;
 103         sg_init_table(sglist, nr_pages);
 104
 105         if (PageHighMem(pages[0]))
 106                 /* DMA to highmem pages might not work */
 107                 goto highmem;
 108         sg_set_page(&sglist[0], pages[0],
 109                         min_t(size_t, PAGE_SIZE - offset, size), offset);
 110         size -= min_t(size_t, PAGE_SIZE - offset, size);
 111         for (i = 1; i < nr_pages; i++) {
 112                 if (NULL == pages[i])
 113                         goto nopage;
 114                 if (PageHighMem(pages[i]))
 115                         goto highmem;
 116                 sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
 117                 size -= min_t(size_t, PAGE_SIZE, size);
 118         }
 119         return sglist;
 120
 121 nopage:
 122         dprintk(2, "sgl: oops - no page\n");
 123         vfree(sglist);
 124         return NULL;
 125
 126 highmem:
 127         dprintk(2, "sgl: oops - highmem page\n");
 128         vfree(sglist);
 129         return NULL;
 130 }
 131
 132 /* --------------------------------------------------------------------- */
 133
 134 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
 135 {
 136         struct videobuf_dma_sg_memory *mem = buf->priv;
 137         BUG_ON(!mem);
 138
 139         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 140
 141         return &mem->dma;
 142 }
 143 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 144
 145 static void videobuf_dma_init(struct videobuf_dmabuf *dma)
 146 {
 147         memset(dma, 0, sizeof(*dma));
 148         dma->magic = MAGIC_DMABUF;
 149 }
 150
 151 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 152                         int direction, unsigned long data, unsigned long size)
 153 {
 154         unsigned long first, last;
 155         int err, rw = 0;
 156         unsigned int flags = FOLL_FORCE;
 157
 158         dma->direction = direction;
 159         switch (dma->direction) {
 160         case DMA_FROM_DEVICE:
 161                 rw = READ;
 162                 break;
 163         case DMA_TO_DEVICE:
 164                 rw = WRITE;
 165                 break;
 166         default:
 167                 BUG();
 168         }
 169
 170         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 171         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 172         dma->offset = data & ~PAGE_MASK;
 173         dma->size = size;
 174         dma->nr_pages = last-first+1;
 175         dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
 176                                    GFP_KERNEL);
 177         if (NULL == dma->pages)
 178                 return -ENOMEM;
 179
 180         if (rw == READ)
 181                 flags |= FOLL_WRITE;
 182
 183         dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
 184                 data, size, dma->nr_pages);
 185
 186         err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
 187                              flags | FOLL_LONGTERM, dma->pages, NULL);
 188
 189         if (err != dma->nr_pages) {
 190                 dma->nr_pages = (err >= 0) ? err : 0;
 191                 dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
 192                         dma->nr_pages);
 193                 return err < 0 ? err : -EINVAL;
 194         }
 195         return 0;
 196 }
 197
 198 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 199                            unsigned long data, unsigned long size)
 200 {
 201         int ret;
 202
 203         mmap_read_lock(current->mm);
 204         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 205         mmap_read_unlock(current->mm);
 206
 207         return ret;
 208 }
 209
 210 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 211                                     unsigned long nr_pages)
 212 {
 213         int i;
 214
 215         dprintk(1, "init kernel [%lu pages]\n", nr_pages);
 216
 217         dma->direction = direction;
 218         dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
 219                                    GFP_KERNEL);
 220         if (!dma->vaddr_pages)
 221                 return -ENOMEM;
 222
 223         dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
 224         if (!dma->dma_addr) {
 225                 kfree(dma->vaddr_pages);
 226                 return -ENOMEM;
 227         }
 228         for (i = 0; i < nr_pages; i++) {
 229                 void *addr;
 230
 231                 addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
 232                                           &(dma->dma_addr[i]), GFP_KERNEL);
 233                 if (addr == NULL)
 234                         goto out_free_pages;
 235
 236                 dma->vaddr_pages[i] = virt_to_page(addr);
 237         }
 238         dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
 239                           PAGE_KERNEL);
 240         if (NULL == dma->vaddr) {
 241                 dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
 242                 goto out_free_pages;
 243         }
 244
 245         dprintk(1, "vmalloc is at addr %p, size=%lu\n",
 246                 dma->vaddr, nr_pages << PAGE_SHIFT);
 247
 248         memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
 249         dma->nr_pages = nr_pages;
 250
 251         return 0;
 252 out_free_pages:
 253         while (i > 0) {
 254                 void *addr;
 255
 256                 i--;
 257                 addr = page_address(dma->vaddr_pages[i]);
 258                 dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
 259         }
 260         kfree(dma->dma_addr);
 261         dma->dma_addr = NULL;
 262         kfree(dma->vaddr_pages);
 263         dma->vaddr_pages = NULL;
 264
 265         return -ENOMEM;
 266
 267 }
 268
 269 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 270                               dma_addr_t addr, unsigned long nr_pages)
 271 {
 272         dprintk(1, "init overlay [%lu pages @ bus 0x%lx]\n",
 273                 nr_pages, (unsigned long)addr);
 274         dma->direction = direction;
 275
 276         if (0 == addr)
 277                 return -EINVAL;
 278
 279         dma->bus_addr = addr;
 280         dma->nr_pages = nr_pages;
 281
 282         return 0;
 283 }
 284
 285 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 286 {
 287         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 288         BUG_ON(0 == dma->nr_pages);
 289
 290         if (dma->pages) {
 291                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 292                                                    dma->offset, dma->size);
 293         }
 294         if (dma->vaddr) {
 295                 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
 296                                                      dma->nr_pages);
 297         }
 298         if (dma->bus_addr) {
 299                 dma->sglist = vmalloc(sizeof(*dma->sglist));
 300                 if (NULL != dma->sglist) {
 301                         dma->sglen = 1;
 302                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr
 303                                                         & PAGE_MASK;
 304                         dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
 305                         sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
 306                 }
 307         }
 308         if (NULL == dma->sglist) {
 309                 dprintk(1, "scatterlist is NULL\n");
 310                 return -ENOMEM;
 311         }
 312         if (!dma->bus_addr) {
 313                 dma->sglen = dma_map_sg(dev, dma->sglist,
 314                                         dma->nr_pages, dma->direction);
 315                 if (0 == dma->sglen) {
 316                         printk(KERN_WARNING
 317                                "%s: videobuf_map_sg failed\n", __func__);
 318                         vfree(dma->sglist);
 319                         dma->sglist = NULL;
 320                         dma->sglen = 0;
 321                         return -ENOMEM;
 322                 }
 323         }
 324
 325         return 0;
 326 }
 327
 328 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 329 {
 330         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 331
 332         if (!dma->sglen)
 333                 return 0;
 334
 335         dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);
 336
 337         vfree(dma->sglist);
 338         dma->sglist = NULL;
 339         dma->sglen = 0;
 340
 341         return 0;
 342 }
 343 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 344
 345 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 346 {
 347         int i;
 348         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 349         BUG_ON(dma->sglen);
 350
 351         if (dma->pages) {
 352                 unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
 353                                             dma->direction == DMA_FROM_DEVICE);
 354                 kfree(dma->pages);
 355                 dma->pages = NULL;
 356         }
 357
 358         if (dma->dma_addr) {
 359                 for (i = 0; i < dma->nr_pages; i++) {
 360                         void *addr;
 361
 362                         addr = page_address(dma->vaddr_pages[i]);
 363                         dma_free_coherent(dma->dev, PAGE_SIZE, addr,
 364                                           dma->dma_addr[i]);
 365                 }
 366                 kfree(dma->dma_addr);
 367                 dma->dma_addr = NULL;
 368                 kfree(dma->vaddr_pages);
 369                 dma->vaddr_pages = NULL;
 370                 vunmap(dma->vaddr);
 371                 dma->vaddr = NULL;
 372         }
 373
 374         if (dma->bus_addr)
 375                 dma->bus_addr = 0;
 376         dma->direction = DMA_NONE;
 377
 378         return 0;
 379 }
 380 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 381
 382 /* --------------------------------------------------------------------- */
 383
 384 static void videobuf_vm_open(struct vm_area_struct *vma)
 385 {
 386         struct videobuf_mapping *map = vma->vm_private_data;
 387
 388         dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
 389                 map->count, vma->vm_start, vma->vm_end);
 390
 391         map->count++;
 392 }
 393
 394 static void videobuf_vm_close(struct vm_area_struct *vma)
 395 {
 396         struct videobuf_mapping *map = vma->vm_private_data;
 397         struct videobuf_queue *q = map->q;
 398         struct videobuf_dma_sg_memory *mem;
 399         int i;
 400
 401         dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
 402                 map->count, vma->vm_start, vma->vm_end);
 403
 404         map->count--;
 405         if (0 == map->count) {
 406                 dprintk(1, "munmap %p q=%p\n", map, q);
 407                 videobuf_queue_lock(q);
 408                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 409                         if (NULL == q->bufs[i])
 410                                 continue;
 411                         mem = q->bufs[i]->priv;
 412                         if (!mem)
 413                                 continue;
 414
 415                         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 416
 417                         if (q->bufs[i]->map != map)
 418                                 continue;
 419                         q->bufs[i]->map   = NULL;
 420                         q->bufs[i]->baddr = 0;
 421                         q->ops->buf_release(q, q->bufs[i]);
 422                 }
 423                 videobuf_queue_unlock(q);
 424                 kfree(map);
 425         }
 426 }
 427
 428 /*
 429  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 430  * memory location with 32bit PCI devices (i.e. don't use highmem for
 431  * now ...).  Bounce buffers don't work very well for the data rates
 432  * video capture has.
 433  */
 434 static vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
 435 {
 436         struct vm_area_struct *vma = vmf->vma;
 437         struct page *page;
 438
 439         dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
 440                 vmf->address, vma->vm_start, vma->vm_end);
 441
 442         page = alloc_page(GFP_USER | __GFP_DMA32);
 443         if (!page)
 444                 return VM_FAULT_OOM;
 445         clear_user_highpage(page, vmf->address);
 446         vmf->page = page;
 447
 448         return 0;
 449 }
 450
 451 static const struct vm_operations_struct videobuf_vm_ops = {
 452         .open   = videobuf_vm_open,
 453         .close  = videobuf_vm_close,
 454         .fault  = videobuf_vm_fault,
 455 };
 456
 457 /* ---------------------------------------------------------------------
 458  * SG handlers for the generic methods
 459  */
 460
 461 /* Allocated area consists on 3 parts:
 462         struct video_buffer
 463         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 464         struct videobuf_dma_sg_memory
 465  */
 466
 467 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
 468 {
 469         struct videobuf_dma_sg_memory *mem;
 470         struct videobuf_buffer *vb;
 471
 472         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 473         if (!vb)
 474                 return vb;
 475
 476         mem = vb->priv = ((char *)vb) + size;
 477         mem->magic = MAGIC_SG_MEM;
 478
 479         videobuf_dma_init(&mem->dma);
 480
 481         dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 482                 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 483                 mem, (long)sizeof(*mem));
 484
 485         return vb;
 486 }
 487
 488 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 489 {
 490         struct videobuf_dma_sg_memory *mem = buf->priv;
 491         BUG_ON(!mem);
 492
 493         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 494
 495         return mem->dma.vaddr;
 496 }
 497
 498 static int __videobuf_iolock(struct videobuf_queue *q,
 499                              struct videobuf_buffer *vb,
 500                              struct v4l2_framebuffer *fbuf)
 501 {
 502         struct videobuf_dma_sg_memory *mem = vb->priv;
 503         unsigned long pages;
 504         dma_addr_t bus;
 505         int err;
 506
 507         BUG_ON(!mem);
 508
 509         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 510
 511         if (!mem->dma.dev)
 512                 mem->dma.dev = q->dev;
 513         else
 514                 WARN_ON(mem->dma.dev != q->dev);
 515
 516         switch (vb->memory) {
 517         case V4L2_MEMORY_MMAP:
 518         case V4L2_MEMORY_USERPTR:
 519                 if (0 == vb->baddr) {
 520                         /* no userspace addr -- kernel bounce buffer */
 521                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 522                         err = videobuf_dma_init_kernel(&mem->dma,
 523                                                        DMA_FROM_DEVICE,
 524                                                        pages);
 525                         if (0 != err)
 526                                 return err;
 527                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 528                         /* dma directly to userspace */
 529                         err = videobuf_dma_init_user(&mem->dma,
 530                                                      DMA_FROM_DEVICE,
 531                                                      vb->baddr, vb->bsize);
 532                         if (0 != err)
 533                                 return err;
 534                 } else {
 535                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 536                         buffers can only be called from videobuf_qbuf
 537                         we take current->mm->mmap_lock there, to prevent
 538                         locking inversion, so don't take it here */
 539
 540                         err = videobuf_dma_init_user_locked(&mem->dma,
 541                                                       DMA_FROM_DEVICE,
 542                                                       vb->baddr, vb->bsize);
 543                         if (0 != err)
 544                                 return err;
 545                 }
 546                 break;
 547         case V4L2_MEMORY_OVERLAY:
 548                 if (NULL == fbuf)
 549                         return -EINVAL;
 550                 /* FIXME: need sanity checks for vb->boff */
 551                 /*
 552                  * Using a double cast to avoid compiler warnings when
 553                  * building for PAE. Compiler doesn't like direct casting
 554                  * of a 32 bit ptr to 64 bit integer.
 555                  */
 556                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 557                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 558                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 559                                                 bus, pages);
 560                 if (0 != err)
 561                         return err;
 562                 break;
 563         default:
 564                 BUG();
 565         }
 566         err = videobuf_dma_map(q->dev, &mem->dma);
 567         if (0 != err)
 568                 return err;
 569
 570         return 0;
 571 }
 572
 573 static int __videobuf_sync(struct videobuf_queue *q,
 574                            struct videobuf_buffer *buf)
 575 {
 576         struct videobuf_dma_sg_memory *mem = buf->priv;
 577         BUG_ON(!mem || !mem->dma.sglen);
 578
 579         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 580         MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
 581
 582         dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
 583                             mem->dma.nr_pages, mem->dma.direction);
 584
 585         return 0;
 586 }
 587
 588 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 589                                   struct videobuf_buffer *buf,
 590                                   struct vm_area_struct *vma)
 591 {
 592         struct videobuf_dma_sg_memory *mem = buf->priv;
 593         struct videobuf_mapping *map;
 594         unsigned int first, last, size = 0, i;
 595         int retval;
 596
 597         retval = -EINVAL;
 598
 599         BUG_ON(!mem);
 600         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 601
 602         /* look for first buffer to map */
 603         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 604                 if (buf == q->bufs[first]) {
 605                         size = PAGE_ALIGN(q->bufs[first]->bsize);
 606                         break;
 607                 }
 608         }
 609
 610         /* paranoia, should never happen since buf is always valid. */
 611         if (!size) {
 612                 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
 613                                 (vma->vm_pgoff << PAGE_SHIFT));
 614                 goto done;
 615         }
 616
 617         last = first;
 618
 619         /* create mapping + update buffer list */
 620         retval = -ENOMEM;
 621         map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 622         if (NULL == map)
 623                 goto done;
 624
 625         size = 0;
 626         for (i = first; i <= last; i++) {
 627                 if (NULL == q->bufs[i])
 628                         continue;
 629                 q->bufs[i]->map   = map;
 630                 q->bufs[i]->baddr = vma->vm_start + size;
 631                 size += PAGE_ALIGN(q->bufs[i]->bsize);
 632         }
 633
 634         map->count    = 1;
 635         map->q        = q;
 636         vma->vm_ops   = &videobuf_vm_ops;
 637         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 638         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 639         vma->vm_private_data = map;
 640         dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 641                 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
 642         retval = 0;
 643
 644 done:
 645         return retval;
 646 }
 647
 648 static struct videobuf_qtype_ops sg_ops = {
 649         .magic        = MAGIC_QTYPE_OPS,
 650
 651         .alloc_vb     = __videobuf_alloc_vb,
 652         .iolock       = __videobuf_iolock,
 653         .sync         = __videobuf_sync,
 654         .mmap_mapper  = __videobuf_mmap_mapper,
 655         .vaddr        = __videobuf_to_vaddr,
 656 };
 657
 658 void *videobuf_sg_alloc(size_t size)
 659 {
 660         struct videobuf_queue q;
 661
 662         /* Required to make generic handler to call __videobuf_alloc */
 663         q.int_ops = &sg_ops;
 664
 665         q.msize = size;
 666
 667         return videobuf_alloc_vb(&q);
 668 }
 669 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 670
 671 void videobuf_queue_sg_init(struct videobuf_queue *q,
 672                          const struct videobuf_queue_ops *ops,
 673                          struct device *dev,
 674                          spinlock_t *irqlock,
 675                          enum v4l2_buf_type type,
 676                          enum v4l2_field field,
 677                          unsigned int msize,
 678                          void *priv,
 679                          struct mutex *ext_lock)
 680 {
 681         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 682                                  priv, &sg_ops, ext_lock);
 683 }
 684 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 685