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 gatter
   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/slab.h>
  25 #include <linux/interrupt.h>
  26
  27 #include <linux/dma-mapping.h>
  28 #include <linux/vmalloc.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/scatterlist.h>
  31 #include <asm/page.h>
  32 #include <asm/pgtable.h>
  33
  34 #include <media/videobuf-dma-sg.h>
  35
  36 #define MAGIC_DMABUF 0x19721112
  37 #define MAGIC_SG_MEM 0x17890714
  38
  39 #define MAGIC_CHECK(is,should)  if (unlikely((is) != (should))) \
  40         { printk(KERN_ERR "magic mismatch: %x (expected %x)\n",is,should); BUG(); }
  41
  42 static int debug;
  43 module_param(debug, int, 0644);
  44
  45 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
  46 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  47 MODULE_LICENSE("GPL");
  48
  49 #define dprintk(level, fmt, arg...)     if (debug >= level) \
  50         printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
  51
  52 /* --------------------------------------------------------------------- */
  53
  54 struct scatterlist*
  55 videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
  56 {
  57         struct scatterlist *sglist;
  58         struct page *pg;
  59         int i;
  60
  61         sglist = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
  62         if (NULL == sglist)
  63                 return NULL;
  64         sg_init_table(sglist, nr_pages);
  65         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  66                 pg = vmalloc_to_page(virt);
  67                 if (NULL == pg)
  68                         goto err;
  69                 BUG_ON(PageHighMem(pg));
  70                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  71         }
  72         return sglist;
  73
  74  err:
  75         kfree(sglist);
  76         return NULL;
  77 }
  78
  79 struct scatterlist*
  80 videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
  81 {
  82         struct scatterlist *sglist;
  83         int i = 0;
  84
  85         if (NULL == pages[0])
  86                 return NULL;
  87         sglist = kcalloc(nr_pages, sizeof(*sglist), GFP_KERNEL);
  88         if (NULL == sglist)
  89                 return NULL;
  90         sg_init_table(sglist, nr_pages);
  91
  92         if (NULL == pages[0])
  93                 goto nopage;
  94         if (PageHighMem(pages[0]))
  95                 /* DMA to highmem pages might not work */
  96                 goto highmem;
  97         sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
  98         for (i = 1; i < nr_pages; i++) {
  99                 if (NULL == pages[i])
 100                         goto nopage;
 101                 if (PageHighMem(pages[i]))
 102                         goto highmem;
 103                 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
 104         }
 105         return sglist;
 106
 107  nopage:
 108         dprintk(2,"sgl: oops - no page\n");
 109         kfree(sglist);
 110         return NULL;
 111
 112  highmem:
 113         dprintk(2,"sgl: oops - highmem page\n");
 114         kfree(sglist);
 115         return NULL;
 116 }
 117
 118 /* --------------------------------------------------------------------- */
 119
 120 struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf)
 121 {
 122         struct videobuf_dma_sg_memory *mem = buf->priv;
 123         BUG_ON(!mem);
 124
 125         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 126
 127         return &mem->dma;
 128 }
 129
 130 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 131 {
 132         memset(dma,0,sizeof(*dma));
 133         dma->magic = MAGIC_DMABUF;
 134 }
 135
 136 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 137                         int direction, unsigned long data, unsigned long size)
 138 {
 139         unsigned long first,last;
 140         int err, rw = 0;
 141
 142         dma->direction = direction;
 143         switch (dma->direction) {
 144         case DMA_FROM_DEVICE:
 145                 rw = READ;
 146                 break;
 147         case DMA_TO_DEVICE:
 148                 rw = WRITE;
 149                 break;
 150         default:
 151                 BUG();
 152         }
 153
 154         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 155         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 156         dma->offset   = data & ~PAGE_MASK;
 157         dma->nr_pages = last-first+1;
 158         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page*),
 159                              GFP_KERNEL);
 160         if (NULL == dma->pages)
 161                 return -ENOMEM;
 162         dprintk(1,"init user [0x%lx+0x%lx => %d pages]\n",
 163                 data,size,dma->nr_pages);
 164
 165         dma->varea = (void *) data;
 166
 167
 168         err = get_user_pages(current,current->mm,
 169                              data & PAGE_MASK, dma->nr_pages,
 170                              rw == READ, 1, /* force */
 171                              dma->pages, NULL);
 172
 173         if (err != dma->nr_pages) {
 174                 dma->nr_pages = (err >= 0) ? err : 0;
 175                 dprintk(1,"get_user_pages: err=%d [%d]\n",err,dma->nr_pages);
 176                 return err < 0 ? err : -EINVAL;
 177         }
 178         return 0;
 179 }
 180
 181 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 182                            unsigned long data, unsigned long size)
 183 {
 184         int ret;
 185         down_read(&current->mm->mmap_sem);
 186         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 187         up_read(&current->mm->mmap_sem);
 188
 189         return ret;
 190 }
 191
 192 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 193                              int nr_pages)
 194 {
 195         dprintk(1,"init kernel [%d pages]\n",nr_pages);
 196         dma->direction = direction;
 197         dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
 198         if (NULL == dma->vmalloc) {
 199                 dprintk(1,"vmalloc_32(%d pages) failed\n",nr_pages);
 200                 return -ENOMEM;
 201         }
 202         dprintk(1,"vmalloc is at addr 0x%08lx, size=%d\n",
 203                                 (unsigned long)dma->vmalloc,
 204                                 nr_pages << PAGE_SHIFT);
 205         memset(dma->vmalloc,0,nr_pages << PAGE_SHIFT);
 206         dma->nr_pages = nr_pages;
 207         return 0;
 208 }
 209
 210 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 211                               dma_addr_t addr, int nr_pages)
 212 {
 213         dprintk(1,"init overlay [%d pages @ bus 0x%lx]\n",
 214                 nr_pages,(unsigned long)addr);
 215         dma->direction = direction;
 216         if (0 == addr)
 217                 return -EINVAL;
 218
 219         dma->bus_addr = addr;
 220         dma->nr_pages = nr_pages;
 221         return 0;
 222 }
 223
 224 int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 225 {
 226         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 227         BUG_ON(0 == dma->nr_pages);
 228
 229         if (dma->pages) {
 230                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 231                                                    dma->offset);
 232         }
 233         if (dma->vmalloc) {
 234                 dma->sglist = videobuf_vmalloc_to_sg
 235                                                 (dma->vmalloc,dma->nr_pages);
 236         }
 237         if (dma->bus_addr) {
 238                 dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
 239                 if (NULL != dma->sglist) {
 240                         dma->sglen  = 1;
 241                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
 242                         dma->sglist[0].offset           = dma->bus_addr & ~PAGE_MASK;
 243                         sg_dma_len(&dma->sglist[0])     = dma->nr_pages * PAGE_SIZE;
 244                 }
 245         }
 246         if (NULL == dma->sglist) {
 247                 dprintk(1,"scatterlist is NULL\n");
 248                 return -ENOMEM;
 249         }
 250         if (!dma->bus_addr) {
 251                 dma->sglen = dma_map_sg(q->dev, dma->sglist,
 252                                         dma->nr_pages, dma->direction);
 253                 if (0 == dma->sglen) {
 254                         printk(KERN_WARNING
 255                                "%s: videobuf_map_sg failed\n",__FUNCTION__);
 256                         kfree(dma->sglist);
 257                         dma->sglist = NULL;
 258                         dma->sglen = 0;
 259                         return -EIO;
 260                 }
 261         }
 262         return 0;
 263 }
 264
 265 int videobuf_dma_sync(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 266 {
 267         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 268         BUG_ON(!dma->sglen);
 269
 270         dma_sync_sg_for_cpu(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 271         return 0;
 272 }
 273
 274 int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
 275 {
 276         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 277         if (!dma->sglen)
 278                 return 0;
 279
 280         dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 281
 282         kfree(dma->sglist);
 283         dma->sglist = NULL;
 284         dma->sglen = 0;
 285         return 0;
 286 }
 287
 288 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 289 {
 290         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 291         BUG_ON(dma->sglen);
 292
 293         if (dma->pages) {
 294                 int i;
 295                 for (i=0; i < dma->nr_pages; i++)
 296                         page_cache_release(dma->pages[i]);
 297                 kfree(dma->pages);
 298                 dma->pages = NULL;
 299         }
 300
 301         vfree(dma->vmalloc);
 302         dma->vmalloc = NULL;
 303         dma->varea = NULL;
 304
 305         if (dma->bus_addr) {
 306                 dma->bus_addr = 0;
 307         }
 308         dma->direction = DMA_NONE;
 309         return 0;
 310 }
 311
 312 /* --------------------------------------------------------------------- */
 313
 314 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 315 {
 316         struct videobuf_queue q;
 317
 318         q.dev = dev;
 319
 320         return videobuf_dma_map(&q, dma);
 321 }
 322
 323 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 324 {
 325         struct videobuf_queue q;
 326
 327         q.dev = dev;
 328
 329         return videobuf_dma_unmap(&q, dma);
 330 }
 331
 332 /* --------------------------------------------------------------------- */
 333
 334 static void
 335 videobuf_vm_open(struct vm_area_struct *vma)
 336 {
 337         struct videobuf_mapping *map = vma->vm_private_data;
 338
 339         dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
 340                 map->count,vma->vm_start,vma->vm_end);
 341         map->count++;
 342 }
 343
 344 static void
 345 videobuf_vm_close(struct vm_area_struct *vma)
 346 {
 347         struct videobuf_mapping *map = vma->vm_private_data;
 348         struct videobuf_queue *q = map->q;
 349         struct videobuf_dma_sg_memory *mem;
 350         int i;
 351
 352         dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
 353                 map->count,vma->vm_start,vma->vm_end);
 354
 355         map->count--;
 356         if (0 == map->count) {
 357                 dprintk(1,"munmap %p q=%p\n",map,q);
 358                 mutex_lock(&q->vb_lock);
 359                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 360                         if (NULL == q->bufs[i])
 361                                 continue;
 362                         mem=q->bufs[i]->priv;
 363
 364                         if (!mem)
 365                                 continue;
 366
 367                         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 368
 369                         if (q->bufs[i]->map != map)
 370                                 continue;
 371                         q->bufs[i]->map   = NULL;
 372                         q->bufs[i]->baddr = 0;
 373                         q->ops->buf_release(q,q->bufs[i]);
 374                 }
 375                 mutex_unlock(&q->vb_lock);
 376                 kfree(map);
 377         }
 378         return;
 379 }
 380
 381 /*
 382  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 383  * memory location with 32bit PCI devices (i.e. don't use highmem for
 384  * now ...).  Bounce buffers don't work very well for the data rates
 385  * video capture has.
 386  */
 387 static int
 388 videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 389 {
 390         struct page *page;
 391
 392         dprintk(3,"fault: fault @ %08lx [vma %08lx-%08lx]\n",
 393                 (unsigned long)vmf->virtual_address,vma->vm_start,vma->vm_end);
 394         page = alloc_page(GFP_USER | __GFP_DMA32);
 395         if (!page)
 396                 return VM_FAULT_OOM;
 397         clear_user_page(page_address(page), (unsigned long)vmf->virtual_address,
 398                         page);
 399         vmf->page = page;
 400         return 0;
 401 }
 402
 403 static struct vm_operations_struct videobuf_vm_ops =
 404 {
 405         .open     = videobuf_vm_open,
 406         .close    = videobuf_vm_close,
 407         .fault    = videobuf_vm_fault,
 408 };
 409
 410 /* ---------------------------------------------------------------------
 411  * SG handlers for the generic methods
 412  */
 413
 414 /* Allocated area consists on 3 parts:
 415         struct video_buffer
 416         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 417         struct videobuf_dma_sg_memory
 418  */
 419
 420 static void *__videobuf_alloc(size_t size)
 421 {
 422         struct videobuf_dma_sg_memory *mem;
 423         struct videobuf_buffer *vb;
 424
 425         vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);
 426
 427         mem = vb->priv = ((char *)vb)+size;
 428         mem->magic=MAGIC_SG_MEM;
 429
 430         videobuf_dma_init(&mem->dma);
 431
 432         dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 433                 __FUNCTION__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
 434                 mem,(long)sizeof(*mem));
 435
 436         return vb;
 437 }
 438
 439 static int __videobuf_iolock (struct videobuf_queue* q,
 440                               struct videobuf_buffer *vb,
 441                               struct v4l2_framebuffer *fbuf)
 442 {
 443         int err,pages;
 444         dma_addr_t bus;
 445         struct videobuf_dma_sg_memory *mem = vb->priv;
 446         BUG_ON(!mem);
 447
 448         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 449
 450         switch (vb->memory) {
 451         case V4L2_MEMORY_MMAP:
 452         case V4L2_MEMORY_USERPTR:
 453                 if (0 == vb->baddr) {
 454                         /* no userspace addr -- kernel bounce buffer */
 455                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 456                         err = videobuf_dma_init_kernel( &mem->dma,
 457                                                         DMA_FROM_DEVICE,
 458                                                         pages );
 459                         if (0 != err)
 460                                 return err;
 461                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 462                         /* dma directly to userspace */
 463                         err = videobuf_dma_init_user( &mem->dma,
 464                                                       DMA_FROM_DEVICE,
 465                                                       vb->baddr,vb->bsize );
 466                         if (0 != err)
 467                                 return err;
 468                 } else {
 469                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 470                         buffers can only be called from videobuf_qbuf
 471                         we take current->mm->mmap_sem there, to prevent
 472                         locking inversion, so don't take it here */
 473
 474                         err = videobuf_dma_init_user_locked(&mem->dma,
 475                                                       DMA_FROM_DEVICE,
 476                                                       vb->baddr, vb->bsize);
 477                         if (0 != err)
 478                                 return err;
 479                 }
 480                 break;
 481         case V4L2_MEMORY_OVERLAY:
 482                 if (NULL == fbuf)
 483                         return -EINVAL;
 484                 /* FIXME: need sanity checks for vb->boff */
 485                 /*
 486                  * Using a double cast to avoid compiler warnings when
 487                  * building for PAE. Compiler doesn't like direct casting
 488                  * of a 32 bit ptr to 64 bit integer.
 489                  */
 490                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 491                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 492                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 493                                                 bus, pages);
 494                 if (0 != err)
 495                         return err;
 496                 break;
 497         default:
 498                 BUG();
 499         }
 500         err = videobuf_dma_map(q, &mem->dma);
 501         if (0 != err)
 502                 return err;
 503
 504         return 0;
 505 }
 506
 507 static int __videobuf_sync(struct videobuf_queue *q,
 508                            struct videobuf_buffer *buf)
 509 {
 510         struct videobuf_dma_sg_memory *mem = buf->priv;
 511         BUG_ON(!mem);
 512         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 513
 514         return  videobuf_dma_sync(q,&mem->dma);
 515 }
 516
 517 static int __videobuf_mmap_free(struct videobuf_queue *q)
 518 {
 519         int i;
 520
 521         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 522                 if (q->bufs[i]) {
 523                         if (q->bufs[i]->map)
 524                                 return -EBUSY;
 525                 }
 526         }
 527
 528         return 0;
 529 }
 530
 531 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 532                          struct vm_area_struct *vma)
 533 {
 534         struct videobuf_dma_sg_memory *mem;
 535         struct videobuf_mapping *map;
 536         unsigned int first,last,size,i;
 537         int retval;
 538
 539         retval = -EINVAL;
 540         if (!(vma->vm_flags & VM_WRITE)) {
 541                 dprintk(1,"mmap app bug: PROT_WRITE please\n");
 542                 goto done;
 543         }
 544         if (!(vma->vm_flags & VM_SHARED)) {
 545                 dprintk(1,"mmap app bug: MAP_SHARED please\n");
 546                 goto done;
 547         }
 548
 549         /* look for first buffer to map */
 550         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 551                 if (NULL == q->bufs[first])
 552                         continue;
 553                 mem=q->bufs[first]->priv;
 554                 BUG_ON(!mem);
 555                 MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 556
 557                 if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
 558                         continue;
 559                 if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
 560                         break;
 561         }
 562         if (VIDEO_MAX_FRAME == first) {
 563                 dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
 564                         (vma->vm_pgoff << PAGE_SHIFT));
 565                 goto done;
 566         }
 567
 568         /* look for last buffer to map */
 569         for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
 570                 if (NULL == q->bufs[last])
 571                         continue;
 572                 if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 573                         continue;
 574                 if (q->bufs[last]->map) {
 575                         retval = -EBUSY;
 576                         goto done;
 577                 }
 578                 size += q->bufs[last]->bsize;
 579                 if (size == (vma->vm_end - vma->vm_start))
 580                         break;
 581         }
 582         if (VIDEO_MAX_FRAME == last) {
 583                 dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
 584                         (vma->vm_end - vma->vm_start));
 585                 goto done;
 586         }
 587
 588         /* create mapping + update buffer list */
 589         retval = -ENOMEM;
 590         map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
 591         if (NULL == map)
 592                 goto done;
 593         for (size = 0, i = first; i <= last; size += q->bufs[i++]->bsize) {
 594                 q->bufs[i]->map   = map;
 595                 q->bufs[i]->baddr = vma->vm_start + size;
 596         }
 597         map->count    = 1;
 598         map->start    = vma->vm_start;
 599         map->end      = vma->vm_end;
 600         map->q        = q;
 601         vma->vm_ops   = &videobuf_vm_ops;
 602         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 603         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 604         vma->vm_private_data = map;
 605         dprintk(1,"mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 606                 map,q,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
 607         retval = 0;
 608
 609  done:
 610         return retval;
 611 }
 612
 613 static int __videobuf_copy_to_user ( struct videobuf_queue *q,
 614                                 char __user *data, size_t count,
 615                                 int nonblocking )
 616 {
 617         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 618         BUG_ON(!mem);
 619         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 620
 621         /* copy to userspace */
 622         if (count > q->read_buf->size - q->read_off)
 623                 count = q->read_buf->size - q->read_off;
 624
 625         if (copy_to_user(data, mem->dma.vmalloc+q->read_off, count))
 626                 return -EFAULT;
 627
 628         return count;
 629 }
 630
 631 static int __videobuf_copy_stream ( struct videobuf_queue *q,
 632                                 char __user *data, size_t count, size_t pos,
 633                                 int vbihack, int nonblocking )
 634 {
 635         unsigned int  *fc;
 636         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 637         BUG_ON(!mem);
 638         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 639
 640         if (vbihack) {
 641                 /* dirty, undocumented hack -- pass the frame counter
 642                         * within the last four bytes of each vbi data block.
 643                         * We need that one to maintain backward compatibility
 644                         * to all vbi decoding software out there ... */
 645                 fc  = (unsigned int*)mem->dma.vmalloc;
 646                 fc += (q->read_buf->size>>2) -1;
 647                 *fc = q->read_buf->field_count >> 1;
 648                 dprintk(1,"vbihack: %d\n",*fc);
 649         }
 650
 651         /* copy stuff using the common method */
 652         count = __videobuf_copy_to_user (q,data,count,nonblocking);
 653
 654         if ( (count==-EFAULT) && (0 == pos) )
 655                 return -EFAULT;
 656
 657         return count;
 658 }
 659
 660 static struct videobuf_qtype_ops sg_ops = {
 661         .magic        = MAGIC_QTYPE_OPS,
 662
 663         .alloc        = __videobuf_alloc,
 664         .iolock       = __videobuf_iolock,
 665         .sync         = __videobuf_sync,
 666         .mmap_free    = __videobuf_mmap_free,
 667         .mmap_mapper  = __videobuf_mmap_mapper,
 668         .video_copy_to_user = __videobuf_copy_to_user,
 669         .copy_stream  = __videobuf_copy_stream,
 670 };
 671
 672 void *videobuf_sg_alloc(size_t size)
 673 {
 674         struct videobuf_queue q;
 675
 676         /* Required to make generic handler to call __videobuf_alloc */
 677         q.int_ops = &sg_ops;
 678
 679         q.msize = size;
 680
 681         return videobuf_alloc(&q);
 682 }
 683
 684 void videobuf_queue_sg_init(struct videobuf_queue* q,
 685                          struct videobuf_queue_ops *ops,
 686                          struct device *dev,
 687                          spinlock_t *irqlock,
 688                          enum v4l2_buf_type type,
 689                          enum v4l2_field field,
 690                          unsigned int msize,
 691                          void *priv)
 692 {
 693         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 694                                  priv, &sg_ops);
 695 }
 696
 697 /* --------------------------------------------------------------------- */
 698
 699 EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
 700
 701 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 702 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 703 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 704 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 705 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 706 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 707 EXPORT_SYMBOL_GPL(videobuf_dma_sync);
 708 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 709 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 710
 711 EXPORT_SYMBOL_GPL(videobuf_sg_dma_map);
 712 EXPORT_SYMBOL_GPL(videobuf_sg_dma_unmap);
 713 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 714
 715 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 716
 717 /*
 718  * Local variables:
 719  * c-basic-offset: 8
 720  * End:
 721  */