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/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 
111