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