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