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@kernel.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@kernel.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 
106