LXR linux/include/media/videobuf-dma-sg.h

   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@kernel.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@kernel.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#ifndef _VIDEOBUF_DMA_SG_H
  21#define _VIDEOBUF_DMA_SG_H
  22
  23#include <media/videobuf-core.h>
  24
  25/* --------------------------------------------------------------------- */
  26
  27/*
  28 * A small set of helper functions to manage buffers (both userland
  29 * and kernel) for DMA.
  30 *
  31 * videobuf_dma_init_*()
  32 *      creates a buffer.  The userland version takes a userspace
  33 *      pointer + length.  The kernel version just wants the size and
  34 *      does memory allocation too using vmalloc_32().
  35 *
  36 * videobuf_dma_*()
  37 *      see Documentation/DMA-API-HOWTO.txt, these functions to
  38 *      basically the same.  The map function does also build a
  39 *      scatterlist for the buffer (and unmap frees it ...)
  40 *
  41 * videobuf_dma_free()
  42 *      no comment ...
  43 *
  44 */
  45
  46struct videobuf_dmabuf {
  47        u32                 magic;
  48
  49        /* for userland buffer */
  50        int                 offset;
  51        size_t              size;
  52        struct page         **pages;
  53
  54        /* for kernel buffers */
  55        void                *vaddr;
  56        struct page         **vaddr_pages;
  57        dma_addr_t          *dma_addr;
  58        struct device       *dev;
  59
  60        /* for overlay buffers (pci-pci dma) */
  61        dma_addr_t          bus_addr;
  62
  63        /* common */
  64        struct scatterlist  *sglist;
  65        int                 sglen;
  66        int                 nr_pages;
  67        int                 direction;
  68};
  69
  70struct videobuf_dma_sg_memory {
  71        u32                 magic;
  72
  73        /* for mmap'ed buffers */
  74        struct videobuf_dmabuf  dma;
  75};
  76
  77/*
  78 * Scatter-gather DMA buffer API.
  79 *
  80 * These functions provide a simple way to create a page list and a
  81 * scatter-gather list from a kernel, userspace of physical address and map the
  82 * memory for DMA operation.
  83 *
  84 * Despite the name, this is totally unrelated to videobuf, except that
  85 * videobuf-dma-sg uses the same API internally.
  86 */
  87int videobuf_dma_free(struct videobuf_dmabuf *dma);
  88
  89int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
  90struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
  91
  92void *videobuf_sg_alloc(size_t size);
  93
  94void videobuf_queue_sg_init(struct videobuf_queue *q,
  95                         const struct videobuf_queue_ops *ops,
  96                         struct device *dev,
  97                         spinlock_t *irqlock,
  98                         enum v4l2_buf_type type,
  99                         enum v4l2_field field,
 100                         unsigned int msize,
 101                         void *priv,
 102                         struct mutex *ext_lock);
 103
 104#endif /* _VIDEOBUF_DMA_SG_H */
 105
 106