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

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * helper functions for SG DMA video4linux capture buffers
   4 *
   5 * The functions expect the hardware being able to scatter gather
   6 * (i.e. the buffers are not linear in physical memory, but fragmented
   7 * into PAGE_SIZE chunks).  They also assume the driver does not need
   8 * to touch the video data.
   9 *
  10 * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
  11 *
  12 * Highly based on video-buf written originally by:
  13 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
  14 * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
  15 * (c) 2006 Ted Walther and John Sokol
  16 */
  17#ifndef _VIDEOBUF_DMA_SG_H
  18#define _VIDEOBUF_DMA_SG_H
  19
  20#include <media/videobuf-core.h>
  21
  22/* --------------------------------------------------------------------- */
  23
  24/*
  25 * A small set of helper functions to manage buffers (both userland
  26 * and kernel) for DMA.
  27 *
  28 * videobuf_dma_init_*()
  29 *      creates a buffer.  The userland version takes a userspace
  30 *      pointer + length.  The kernel version just wants the size and
  31 *      does memory allocation too using vmalloc_32().
  32 *
  33 * videobuf_dma_*()
  34 *      see Documentation/core-api/dma-api-howto.rst, these functions to
  35 *      basically the same.  The map function does also build a
  36 *      scatterlist for the buffer (and unmap frees it ...)
  37 *
  38 * videobuf_dma_free()
  39 *      no comment ...
  40 *
  41 */
  42
  43struct videobuf_dmabuf {
  44        u32                 magic;
  45
  46        /* for userland buffer */
  47        int                 offset;
  48        size_t              size;
  49        struct page         **pages;
  50
  51        /* for kernel buffers */
  52        void                *vaddr;
  53        struct page         **vaddr_pages;
  54        dma_addr_t          *dma_addr;
  55        struct device       *dev;
  56
  57        /* for overlay buffers (pci-pci dma) */
  58        dma_addr_t          bus_addr;
  59
  60        /* common */
  61        struct scatterlist  *sglist;
  62        int                 sglen;
  63        unsigned long       nr_pages;
  64        int                 direction;
  65};
  66
  67struct videobuf_dma_sg_memory {
  68        u32                 magic;
  69
  70        /* for mmap'ed buffers */
  71        struct videobuf_dmabuf  dma;
  72};
  73
  74/*
  75 * Scatter-gather DMA buffer API.
  76 *
  77 * These functions provide a simple way to create a page list and a
  78 * scatter-gather list from a kernel, userspace of physical address and map the
  79 * memory for DMA operation.
  80 *
  81 * Despite the name, this is totally unrelated to videobuf, except that
  82 * videobuf-dma-sg uses the same API internally.
  83 */
  84int videobuf_dma_free(struct videobuf_dmabuf *dma);
  85
  86int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
  87struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
  88
  89void *videobuf_sg_alloc(size_t size);
  90
  91void videobuf_queue_sg_init(struct videobuf_queue *q,
  92                         const struct videobuf_queue_ops *ops,
  93                         struct device *dev,
  94                         spinlock_t *irqlock,
  95                         enum v4l2_buf_type type,
  96                         enum v4l2_field field,
  97                         unsigned int msize,
  98                         void *priv,
  99                         struct mutex *ext_lock);
 100
 101#endif /* _VIDEOBUF_DMA_SG_H */
 102
 103