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videobuf-dma-sg.h
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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, <[email protected]>
10  *
11  * Highly based on video-buf written originally by:
12  * (c) 2001,02 Gerd Knorr <[email protected]>
13  * (c) 2006 Mauro Carvalho Chehab, <[email protected]>
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 
57  /* for overlay buffers (pci-pci dma) */
58  dma_addr_t bus_addr;
59 
60  /* common */
61  struct scatterlist *sglist;
62  int sglen;
63  int nr_pages;
64  int direction;
65 };
66 
67 struct 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  */
84 void videobuf_dma_init(struct videobuf_dmabuf *dma);
85 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
86  unsigned long data, unsigned long size);
87 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
88  int nr_pages);
89 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
90  dma_addr_t addr, int nr_pages);
91 int videobuf_dma_free(struct videobuf_dmabuf *dma);
92 
93 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma);
94 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
95 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
96 
97 void *videobuf_sg_alloc(size_t size);
98 
99 void videobuf_queue_sg_init(struct videobuf_queue *q,
100  const struct videobuf_queue_ops *ops,
101  struct device *dev,
102  spinlock_t *irqlock,
103  enum v4l2_buf_type type,
104  enum v4l2_field field,
105  unsigned int msize,
106  void *priv,
107  struct mutex *ext_lock);
108 
109 #endif /* _VIDEOBUF_DMA_SG_H */
110 
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