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@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 #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
  46 struct 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
  70 struct 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  */
  87 int videobuf_dma_free(struct videobuf_dmabuf *dma);
  88
  89 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
  90 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
  91
  92 void *videobuf_sg_alloc(size_t size);
  93
  94 void 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