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 gatter
   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 <media/videobuf-core.h>
  22
  23 /* --------------------------------------------------------------------- */
  24
  25 /*
  26  * Return a scatterlist for some page-aligned vmalloc()'ed memory
  27  * block (NULL on errors).  Memory for the scatterlist is allocated
  28  * using kmalloc.  The caller must free the memory.
  29  */
  30 struct scatterlist* videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages);
  31
  32 /*
  33  * Return a scatterlist for a an array of userpages (NULL on errors).
  34  * Memory for the scatterlist is allocated using kmalloc.  The caller
  35  * must free the memory.
  36  */
  37 struct scatterlist* videobuf_pages_to_sg(struct page **pages, int nr_pages,
  38                                          int offset);
  39
  40 /* --------------------------------------------------------------------- */
  41
  42 /*
  43  * A small set of helper functions to manage buffers (both userland
  44  * and kernel) for DMA.
  45  *
  46  * videobuf_dma_init_*()
  47  *      creates a buffer.  The userland version takes a userspace
  48  *      pointer + length.  The kernel version just wants the size and
  49  *      does memory allocation too using vmalloc_32().
  50  *
  51  * videobuf_dma_*()
  52  *      see Documentation/DMA-mapping.txt, these functions to
  53  *      basically the same.  The map function does also build a
  54  *      scatterlist for the buffer (and unmap frees it ...)
  55  *
  56  * videobuf_dma_free()
  57  *      no comment ...
  58  *
  59  */
  60
  61 struct videobuf_dmabuf {
  62         u32                 magic;
  63
  64         /* for userland buffer */
  65         int                 offset;
  66         struct page         **pages;
  67
  68         /* for kernel buffers */
  69         void                *vmalloc;
  70
  71         /* for overlay buffers (pci-pci dma) */
  72         dma_addr_t          bus_addr;
  73
  74         /* common */
  75         struct scatterlist  *sglist;
  76         int                 sglen;
  77         int                 nr_pages;
  78         int                 direction;
  79 };
  80
  81 struct videobuf_dma_sg_memory
  82 {
  83         u32                 magic;
  84
  85         /* for mmap'ed buffers */
  86         struct videobuf_dmabuf  dma;
  87 };
  88
  89 void videobuf_dma_init(struct videobuf_dmabuf *dma);
  90 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
  91                            unsigned long data, unsigned long size);
  92 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
  93                              int nr_pages);
  94 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
  95                               dma_addr_t addr, int nr_pages);
  96 int videobuf_dma_free(struct videobuf_dmabuf *dma);
  97
  98 int videobuf_dma_map(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
  99 int videobuf_dma_sync(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
 100 int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
 101 struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf);
 102
 103 void *videobuf_sg_alloc(size_t size);
 104
 105 void videobuf_queue_sg_init(struct videobuf_queue* q,
 106                          struct videobuf_queue_ops *ops,
 107                          struct device *dev,
 108                          spinlock_t *irqlock,
 109                          enum v4l2_buf_type type,
 110                          enum v4l2_field field,
 111                          unsigned int msize,
 112                          void *priv);
 113
 114         /*FIXME: these variants are used only on *-alsa code, where videobuf is
 115          * used without queue
 116          */
 117 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma);
 118 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
 119