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 
43 struct 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 	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 int videobuf_dma_free(struct videobuf_dmabuf *dma);
85 
86 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
87 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
88 
89 void *videobuf_sg_alloc(size_t size);
90 
91 void 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