git.oblomov.eu Git - linux-2.6/blob - 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         err = get_user_pages(current,current->mm,
 166                              data & PAGE_MASK, dma->nr_pages,
 167                              rw == READ, 1, /* force */
 168                              dma->pages, NULL);
 169
 170         if (err != dma->nr_pages) {
 171                 dma->nr_pages = (err >= 0) ? err : 0;
 172                 dprintk(1,"get_user_pages: err=%d [%d]\n",err,dma->nr_pages);
 173                 return err < 0 ? err : -EINVAL;
 174         }
 175         return 0;
 176 }
 177
 178 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 179                            unsigned long data, unsigned long size)
 180 {
 181         int ret;
 182         down_read(&current->mm->mmap_sem);
 183         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 184         up_read(&current->mm->mmap_sem);
 185
 186         return ret;
 187 }
 188
 189 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 190                              int nr_pages)
 191 {
 192         dprintk(1,"init kernel [%d pages]\n",nr_pages);
 193         dma->direction = direction;
 194         dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
 195         if (NULL == dma->vmalloc) {
 196                 dprintk(1,"vmalloc_32(%d pages) failed\n",nr_pages);
 197                 return -ENOMEM;
 198         }
 199         dprintk(1,"vmalloc is at addr 0x%08lx, size=%d\n",
 200                                 (unsigned long)dma->vmalloc,
 201                                 nr_pages << PAGE_SHIFT);
 202         memset(dma->vmalloc,0,nr_pages << PAGE_SHIFT);
 203         dma->nr_pages = nr_pages;
 204         return 0;
 205 }
 206
 207 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 208                               dma_addr_t addr, int nr_pages)
 209 {
 210         dprintk(1,"init overlay [%d pages @ bus 0x%lx]\n",
 211                 nr_pages,(unsigned long)addr);
 212         dma->direction = direction;
 213         if (0 == addr)
 214                 return -EINVAL;
 215
 216         dma->bus_addr = addr;
 217         dma->nr_pages = nr_pages;
 218         return 0;
 219 }
 220
 221 int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 222 {
 223         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 224         BUG_ON(0 == dma->nr_pages);
 225
 226         if (dma->pages) {
 227                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 228                                                    dma->offset);
 229         }
 230         if (dma->vmalloc) {
 231                 dma->sglist = videobuf_vmalloc_to_sg
 232                                                 (dma->vmalloc,dma->nr_pages);
 233         }
 234         if (dma->bus_addr) {
 235                 dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
 236                 if (NULL != dma->sglist) {
 237                         dma->sglen  = 1;
 238                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
 239                         dma->sglist[0].offset           = dma->bus_addr & ~PAGE_MASK;
 240                         sg_dma_len(&dma->sglist[0])     = dma->nr_pages * PAGE_SIZE;
 241                 }
 242         }
 243         if (NULL == dma->sglist) {
 244                 dprintk(1,"scatterlist is NULL\n");
 245                 return -ENOMEM;
 246         }
 247         if (!dma->bus_addr) {
 248                 dma->sglen = dma_map_sg(q->dev, dma->sglist,
 249                                         dma->nr_pages, dma->direction);
 250                 if (0 == dma->sglen) {
 251                         printk(KERN_WARNING
 252                                "%s: videobuf_map_sg failed\n",__func__);
 253                         kfree(dma->sglist);
 254                         dma->sglist = NULL;
 255                         dma->sglen = 0;
 256                         return -EIO;
 257                 }
 258         }
 259         return 0;
 260 }
 261
 262 int videobuf_dma_sync(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 263 {
 264         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 265         BUG_ON(!dma->sglen);
 266
 267         dma_sync_sg_for_cpu(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 268         return 0;
 269 }
 270
 271 int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
 272 {
 273         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 274         if (!dma->sglen)
 275                 return 0;
 276
 277         dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 278
 279         kfree(dma->sglist);
 280         dma->sglist = NULL;
 281         dma->sglen = 0;
 282         return 0;
 283 }
 284
 285 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 286 {
 287         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 288         BUG_ON(dma->sglen);
 289
 290         if (dma->pages) {
 291                 int i;
 292                 for (i=0; i < dma->nr_pages; i++)
 293                         page_cache_release(dma->pages[i]);
 294                 kfree(dma->pages);
 295                 dma->pages = NULL;
 296         }
 297
 298         vfree(dma->vmalloc);
 299         dma->vmalloc = NULL;
 300
 301         if (dma->bus_addr) {
 302                 dma->bus_addr = 0;
 303         }
 304         dma->direction = DMA_NONE;
 305         return 0;
 306 }
 307
 308 /* --------------------------------------------------------------------- */
 309
 310 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 311 {
 312         struct videobuf_queue q;
 313
 314         q.dev = dev;
 315
 316         return videobuf_dma_map(&q, dma);
 317 }
 318
 319 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 320 {
 321         struct videobuf_queue q;
 322
 323         q.dev = dev;
 324
 325         return videobuf_dma_unmap(&q, dma);
 326 }
 327
 328 /* --------------------------------------------------------------------- */
 329
 330 static void
 331 videobuf_vm_open(struct vm_area_struct *vma)
 332 {
 333         struct videobuf_mapping *map = vma->vm_private_data;
 334
 335         dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
 336                 map->count,vma->vm_start,vma->vm_end);
 337         map->count++;
 338 }
 339
 340 static void
 341 videobuf_vm_close(struct vm_area_struct *vma)
 342 {
 343         struct videobuf_mapping *map = vma->vm_private_data;
 344         struct videobuf_queue *q = map->q;
 345         struct videobuf_dma_sg_memory *mem;
 346         int i;
 347
 348         dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
 349                 map->count,vma->vm_start,vma->vm_end);
 350
 351         map->count--;
 352         if (0 == map->count) {
 353                 dprintk(1,"munmap %p q=%p\n",map,q);
 354                 mutex_lock(&q->vb_lock);
 355                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 356                         if (NULL == q->bufs[i])
 357                                 continue;
 358                         mem=q->bufs[i]->priv;
 359
 360                         if (!mem)
 361                                 continue;
 362
 363                         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 364
 365                         if (q->bufs[i]->map != map)
 366                                 continue;
 367                         q->bufs[i]->map   = NULL;
 368                         q->bufs[i]->baddr = 0;
 369                         q->ops->buf_release(q,q->bufs[i]);
 370                 }
 371                 mutex_unlock(&q->vb_lock);
 372                 kfree(map);
 373         }
 374         return;
 375 }
 376
 377 /*
 378  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 379  * memory location with 32bit PCI devices (i.e. don't use highmem for
 380  * now ...).  Bounce buffers don't work very well for the data rates
 381  * video capture has.
 382  */
 383 static int
 384 videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 385 {
 386         struct page *page;
 387
 388         dprintk(3,"fault: fault @ %08lx [vma %08lx-%08lx]\n",
 389                 (unsigned long)vmf->virtual_address,vma->vm_start,vma->vm_end);
 390         page = alloc_page(GFP_USER | __GFP_DMA32);
 391         if (!page)
 392                 return VM_FAULT_OOM;
 393         clear_user_page(page_address(page), (unsigned long)vmf->virtual_address,
 394                         page);
 395         vmf->page = page;
 396         return 0;
 397 }
 398
 399 static struct vm_operations_struct videobuf_vm_ops =
 400 {
 401         .open     = videobuf_vm_open,
 402         .close    = videobuf_vm_close,
 403         .fault    = videobuf_vm_fault,
 404 };
 405
 406 /* ---------------------------------------------------------------------
 407  * SG handlers for the generic methods
 408  */
 409
 410 /* Allocated area consists on 3 parts:
 411         struct video_buffer
 412         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 413         struct videobuf_dma_sg_memory
 414  */
 415
 416 static void *__videobuf_alloc(size_t size)
 417 {
 418         struct videobuf_dma_sg_memory *mem;
 419         struct videobuf_buffer *vb;
 420
 421         vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);
 422
 423         mem = vb->priv = ((char *)vb)+size;
 424         mem->magic=MAGIC_SG_MEM;
 425
 426         videobuf_dma_init(&mem->dma);
 427
 428         dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 429                 __func__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
 430                 mem,(long)sizeof(*mem));
 431
 432         return vb;
 433 }
 434
 435 static void *__videobuf_to_vmalloc (struct videobuf_buffer *buf)
 436 {
 437         struct videobuf_dma_sg_memory *mem = buf->priv;
 438         BUG_ON(!mem);
 439
 440         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 441
 442         return mem->dma.vmalloc;
 443 }
 444
 445 static int __videobuf_iolock (struct videobuf_queue* q,
 446                               struct videobuf_buffer *vb,
 447                               struct v4l2_framebuffer *fbuf)
 448 {
 449         int err,pages;
 450         dma_addr_t bus;
 451         struct videobuf_dma_sg_memory *mem = vb->priv;
 452         BUG_ON(!mem);
 453
 454         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 455
 456         switch (vb->memory) {
 457         case V4L2_MEMORY_MMAP:
 458         case V4L2_MEMORY_USERPTR:
 459                 if (0 == vb->baddr) {
 460                         /* no userspace addr -- kernel bounce buffer */
 461                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 462                         err = videobuf_dma_init_kernel( &mem->dma,
 463                                                         DMA_FROM_DEVICE,
 464                                                         pages );
 465                         if (0 != err)
 466                                 return err;
 467                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 468                         /* dma directly to userspace */
 469                         err = videobuf_dma_init_user( &mem->dma,
 470                                                       DMA_FROM_DEVICE,
 471                                                       vb->baddr,vb->bsize );
 472                         if (0 != err)
 473                                 return err;
 474                 } else {
 475                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 476                         buffers can only be called from videobuf_qbuf
 477                         we take current->mm->mmap_sem there, to prevent
 478                         locking inversion, so don't take it here */
 479
 480                         err = videobuf_dma_init_user_locked(&mem->dma,
 481                                                       DMA_FROM_DEVICE,
 482                                                       vb->baddr, vb->bsize);
 483                         if (0 != err)
 484                                 return err;
 485                 }
 486                 break;
 487         case V4L2_MEMORY_OVERLAY:
 488                 if (NULL == fbuf)
 489                         return -EINVAL;
 490                 /* FIXME: need sanity checks for vb->boff */
 491                 /*
 492                  * Using a double cast to avoid compiler warnings when
 493                  * building for PAE. Compiler doesn't like direct casting
 494                  * of a 32 bit ptr to 64 bit integer.
 495                  */
 496                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 497                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 498                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 499                                                 bus, pages);
 500                 if (0 != err)
 501                         return err;
 502                 break;
 503         default:
 504                 BUG();
 505         }
 506         err = videobuf_dma_map(q, &mem->dma);
 507         if (0 != err)
 508                 return err;
 509
 510         return 0;
 511 }
 512
 513 static int __videobuf_sync(struct videobuf_queue *q,
 514                            struct videobuf_buffer *buf)
 515 {
 516         struct videobuf_dma_sg_memory *mem = buf->priv;
 517         BUG_ON(!mem);
 518         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 519
 520         return  videobuf_dma_sync(q,&mem->dma);
 521 }
 522
 523 static int __videobuf_mmap_free(struct videobuf_queue *q)
 524 {
 525         int i;
 526
 527         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 528                 if (q->bufs[i]) {
 529                         if (q->bufs[i]->map)
 530                                 return -EBUSY;
 531                 }
 532         }
 533
 534         return 0;
 535 }
 536
 537 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 538                          struct vm_area_struct *vma)
 539 {
 540         struct videobuf_dma_sg_memory *mem;
 541         struct videobuf_mapping *map;
 542         unsigned int first,last,size,i;
 543         int retval;
 544
 545         retval = -EINVAL;
 546         if (!(vma->vm_flags & VM_WRITE)) {
 547                 dprintk(1,"mmap app bug: PROT_WRITE please\n");
 548                 goto done;
 549         }
 550         if (!(vma->vm_flags & VM_SHARED)) {
 551                 dprintk(1,"mmap app bug: MAP_SHARED please\n");
 552                 goto done;
 553         }
 554
 555         /* This function maintains backwards compatibility with V4L1 and will
 556          * map more than one buffer if the vma length is equal to the combined
 557          * size of multiple buffers than it will map them together.  See
 558          * VIDIOCGMBUF in the v4l spec
 559          *
 560          * TODO: Allow drivers to specify if they support this mode
 561          */
 562
 563         /* look for first buffer to map */
 564         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 565                 if (NULL == q->bufs[first])
 566                         continue;
 567                 mem=q->bufs[first]->priv;
 568                 BUG_ON(!mem);
 569                 MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 570
 571                 if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
 572                         continue;
 573                 if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
 574                         break;
 575         }
 576         if (VIDEO_MAX_FRAME == first) {
 577                 dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
 578                         (vma->vm_pgoff << PAGE_SHIFT));
 579                 goto done;
 580         }
 581
 582         /* look for last buffer to map */
 583         for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
 584                 if (NULL == q->bufs[last])
 585                         continue;
 586                 if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 587                         continue;
 588                 if (q->bufs[last]->map) {
 589                         retval = -EBUSY;
 590                         goto done;
 591                 }
 592                 size += q->bufs[last]->bsize;
 593                 if (size == (vma->vm_end - vma->vm_start))
 594                         break;
 595         }
 596         if (VIDEO_MAX_FRAME == last) {
 597                 dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
 598                         (vma->vm_end - vma->vm_start));
 599                 goto done;
 600         }
 601
 602         /* create mapping + update buffer list */
 603         retval = -ENOMEM;
 604         map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
 605         if (NULL == map)
 606                 goto done;
 607
 608         size = 0;
 609         for (i = first; i <= last; i++) {
 610                 if (NULL == q->bufs[i])
 611                         continue;
 612                 q->bufs[i]->map   = map;
 613                 q->bufs[i]->baddr = vma->vm_start + size;
 614                 size += q->bufs[i]->bsize;
 615         }
 616
 617         map->count    = 1;
 618         map->start    = vma->vm_start;
 619         map->end      = vma->vm_end;
 620         map->q        = q;
 621         vma->vm_ops   = &videobuf_vm_ops;
 622         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 623         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 624         vma->vm_private_data = map;
 625         dprintk(1,"mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 626                 map,q,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
 627         retval = 0;
 628
 629  done:
 630         return retval;
 631 }
 632
 633 static int __videobuf_copy_to_user ( struct videobuf_queue *q,
 634                                 char __user *data, size_t count,
 635                                 int nonblocking )
 636 {
 637         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 638         BUG_ON(!mem);
 639         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 640
 641         /* copy to userspace */
 642         if (count > q->read_buf->size - q->read_off)
 643                 count = q->read_buf->size - q->read_off;
 644
 645         if (copy_to_user(data, mem->dma.vmalloc+q->read_off, count))
 646                 return -EFAULT;
 647
 648         return count;
 649 }
 650
 651 static int __videobuf_copy_stream ( struct videobuf_queue *q,
 652                                 char __user *data, size_t count, size_t pos,
 653                                 int vbihack, int nonblocking )
 654 {
 655         unsigned int  *fc;
 656         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 657         BUG_ON(!mem);
 658         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 659
 660         if (vbihack) {
 661                 /* dirty, undocumented hack -- pass the frame counter
 662                         * within the last four bytes of each vbi data block.
 663                         * We need that one to maintain backward compatibility
 664                         * to all vbi decoding software out there ... */
 665                 fc  = (unsigned int*)mem->dma.vmalloc;
 666                 fc += (q->read_buf->size>>2) -1;
 667                 *fc = q->read_buf->field_count >> 1;
 668                 dprintk(1,"vbihack: %d\n",*fc);
 669         }
 670
 671         /* copy stuff using the common method */
 672         count = __videobuf_copy_to_user (q,data,count,nonblocking);
 673
 674         if ( (count==-EFAULT) && (0 == pos) )
 675                 return -EFAULT;
 676
 677         return count;
 678 }
 679
 680 static struct videobuf_qtype_ops sg_ops = {
 681         .magic        = MAGIC_QTYPE_OPS,
 682
 683         .alloc        = __videobuf_alloc,
 684         .iolock       = __videobuf_iolock,
 685         .sync         = __videobuf_sync,
 686         .mmap_free    = __videobuf_mmap_free,
 687         .mmap_mapper  = __videobuf_mmap_mapper,
 688         .video_copy_to_user = __videobuf_copy_to_user,
 689         .copy_stream  = __videobuf_copy_stream,
 690         .vmalloc      = __videobuf_to_vmalloc,
 691 };
 692
 693 void *videobuf_sg_alloc(size_t size)
 694 {
 695         struct videobuf_queue q;
 696
 697         /* Required to make generic handler to call __videobuf_alloc */
 698         q.int_ops = &sg_ops;
 699
 700         q.msize = size;
 701
 702         return videobuf_alloc(&q);
 703 }
 704
 705 void videobuf_queue_sg_init(struct videobuf_queue* q,
 706                          struct videobuf_queue_ops *ops,
 707                          struct device *dev,
 708                          spinlock_t *irqlock,
 709                          enum v4l2_buf_type type,
 710                          enum v4l2_field field,
 711                          unsigned int msize,
 712                          void *priv)
 713 {
 714         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 715                                  priv, &sg_ops);
 716 }
 717
 718 /* --------------------------------------------------------------------- */
 719
 720 EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
 721
 722 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 723 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 724 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 725 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 726 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 727 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 728 EXPORT_SYMBOL_GPL(videobuf_dma_sync);
 729 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 730 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 731
 732 EXPORT_SYMBOL_GPL(videobuf_sg_dma_map);
 733 EXPORT_SYMBOL_GPL(videobuf_sg_dma_unmap);
 734 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 735
 736 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 737
 738 /*
 739  * Local variables:
 740  * c-basic-offset: 8
 741  * End:
 742  */