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/PCI/PCI-DMA-mapping.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         struct page         **pages;
  52
  53         /* for kernel buffers */
  54         void                *vaddr;
  55
  56         /* for overlay buffers (pci-pci dma) */
  57         dma_addr_t          bus_addr;
  58
  59         /* common */
  60         struct scatterlist  *sglist;
  61         int                 sglen;
  62         int                 nr_pages;
  63         int                 direction;
  64 };
  65
  66 struct videobuf_dma_sg_memory {
  67         u32                 magic;
  68
  69         /* for mmap'ed buffers */
  70         struct videobuf_dmabuf  dma;
  71 };
  72
  73 /*
  74  * Scatter-gather DMA buffer API.
  75  *
  76  * These functions provide a simple way to create a page list and a
  77  * scatter-gather list from a kernel, userspace of physical address and map the
  78  * memory for DMA operation.
  79  *
  80  * Despite the name, this is totally unrelated to videobuf, except that
  81  * videobuf-dma-sg uses the same API internally.
  82  */
  83 void videobuf_dma_init(struct videobuf_dmabuf *dma);
  84 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
  85                            unsigned long data, unsigned long size);
  86 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
  87                              int nr_pages);
  88 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
  89                               dma_addr_t addr, int nr_pages);
  90 int videobuf_dma_free(struct videobuf_dmabuf *dma);
  91
  92 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma);
  93 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
  94 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
  95
  96 void *videobuf_sg_alloc(size_t size);
  97
  98 void videobuf_queue_sg_init(struct videobuf_queue *q,
  99                          const struct videobuf_queue_ops *ops,
 100                          struct device *dev,
 101                          spinlock_t *irqlock,
 102                          enum v4l2_buf_type type,
 103                          enum v4l2_field field,
 104                          unsigned int msize,
 105                          void *priv);
 106
 107 #endif /* _VIDEOBUF_DMA_SG_H */
 108