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  * Return a scatterlist for some page-aligned vmalloc()'ed memory
  29  * block (NULL on errors).  Memory for the scatterlist is allocated
  30  * using kmalloc.  The caller must free the memory.
  31  */
  32 struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages);
  33
  34 /*
  35  * Return a scatterlist for a an array of userpages (NULL on errors).
  36  * Memory for the scatterlist is allocated using kmalloc.  The caller
  37  * must free the memory.
  38  */
  39 struct scatterlist *videobuf_pages_to_sg(struct page **pages, int nr_pages,
  40                                          int offset);
  41
  42 /* --------------------------------------------------------------------- */
  43
  44 /*
  45  * A small set of helper functions to manage buffers (both userland
  46  * and kernel) for DMA.
  47  *
  48  * videobuf_dma_init_*()
  49  *      creates a buffer.  The userland version takes a userspace
  50  *      pointer + length.  The kernel version just wants the size and
  51  *      does memory allocation too using vmalloc_32().
  52  *
  53  * videobuf_dma_*()
  54  *      see Documentation/PCI/PCI-DMA-mapping.txt, these functions to
  55  *      basically the same.  The map function does also build a
  56  *      scatterlist for the buffer (and unmap frees it ...)
  57  *
  58  * videobuf_dma_free()
  59  *      no comment ...
  60  *
  61  */
  62
  63 struct videobuf_dmabuf {
  64         u32                 magic;
  65
  66         /* for userland buffer */
  67         int                 offset;
  68         struct page         **pages;
  69
  70         /* for kernel buffers */
  71         void                *vmalloc;
  72
  73         /* for overlay buffers (pci-pci dma) */
  74         dma_addr_t          bus_addr;
  75
  76         /* common */
  77         struct scatterlist  *sglist;
  78         int                 sglen;
  79         int                 nr_pages;
  80         int                 direction;
  81 };
  82
  83 struct videobuf_dma_sg_memory {
  84         u32                 magic;
  85
  86         /* for mmap'ed buffers */
  87         struct videobuf_dmabuf  dma;
  88 };
  89
  90 void videobuf_dma_init(struct videobuf_dmabuf *dma);
  91 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
  92                            unsigned long data, unsigned long size);
  93 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
  94                              int nr_pages);
  95 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
  96                               dma_addr_t addr, int nr_pages);
  97 int videobuf_dma_free(struct videobuf_dmabuf *dma);
  98
  99 int videobuf_dma_map(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                          const 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
 120 #endif /* _VIDEOBUF_DMA_SG_H */
 121