1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * helper functions for SG DMA video4linux capture buffers
4 *
5 * The functions expect the hardware being able to scatter gather
6 * (i.e. the buffers are not linear in physical memory, but fragmented
7 * into PAGE_SIZE chunks).  They also assume the driver does not need
8 * to touch the video data.
9 *
10 * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
11 *
12 * Highly based on video-buf written originally by:
13 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
14 * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
15 * (c) 2006 Ted Walther and John Sokol
16 */
17#ifndef _VIDEOBUF_DMA_SG_H
18#define _VIDEOBUF_DMA_SG_H
19
20#include <media/videobuf-core.h>
21
22/* --------------------------------------------------------------------- */
23
24/*
25 * A small set of helper functions to manage buffers (both userland
26 * and kernel) for DMA.
27 *
28 * videobuf_dma_init_*()
29 *	creates a buffer.  The userland version takes a userspace
30 *	pointer + length.  The kernel version just wants the size and
31 *	does memory allocation too using vmalloc_32().
32 *
33 * videobuf_dma_*()
34 *	see Documentation/core-api/dma-api-howto.rst, these functions to
35 *	basically the same.  The map function does also build a
36 *	scatterlist for the buffer (and unmap frees it ...)
37 *
38 * videobuf_dma_free()
39 *	no comment ...
40 *
41 */
42
43struct videobuf_dmabuf {
44	u32                 magic;
45
46	/* for userland buffer */
47	int                 offset;
48	size_t		    size;
49	struct page         **pages;
50
51	/* for kernel buffers */
52	void                *vaddr;
53	struct page         **vaddr_pages;
54	dma_addr_t          *dma_addr;
55	struct device       *dev;
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	unsigned long       nr_pages;
64	int                 direction;
65};
66
67struct 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 */
84int videobuf_dma_free(struct videobuf_dmabuf *dma);
85
86int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
87struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
88
89void *videobuf_sg_alloc(size_t size);
90
91void videobuf_queue_sg_init(struct videobuf_queue *q,
92			 const struct videobuf_queue_ops *ops,
93			 struct device *dev,
94			 spinlock_t *irqlock,
95			 enum v4l2_buf_type type,
96			 enum v4l2_field field,
97			 unsigned int msize,
98			 void *priv,
99			 struct mutex *ext_lock);
100
101#endif /* _VIDEOBUF_DMA_SG_H */
102
103