mirror of https://gitee.com/openkylin/linux.git
103 lines
2.8 KiB
C
103 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* helper functions for SG DMA video4linux capture buffers
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*
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* The functions expect the hardware being able to scatter gather
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* (i.e. the buffers are not linear in physical memory, but fragmented
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* into PAGE_SIZE chunks). They also assume the driver does not need
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* to touch the video data.
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*
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* (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
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*
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* Highly based on video-buf written originally by:
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* (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
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* (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
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* (c) 2006 Ted Walther and John Sokol
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*/
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#ifndef _VIDEOBUF_DMA_SG_H
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#define _VIDEOBUF_DMA_SG_H
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#include <media/videobuf-core.h>
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/* --------------------------------------------------------------------- */
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/*
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* A small set of helper functions to manage buffers (both userland
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* and kernel) for DMA.
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*
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* videobuf_dma_init_*()
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* creates a buffer. The userland version takes a userspace
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* pointer + length. The kernel version just wants the size and
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* does memory allocation too using vmalloc_32().
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*
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* videobuf_dma_*()
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* see Documentation/core-api/dma-api-howto.rst, these functions to
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* basically the same. The map function does also build a
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* scatterlist for the buffer (and unmap frees it ...)
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*
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* videobuf_dma_free()
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* no comment ...
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*
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*/
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struct videobuf_dmabuf {
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u32 magic;
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/* for userland buffer */
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int offset;
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size_t size;
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struct page **pages;
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/* for kernel buffers */
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void *vaddr;
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struct page **vaddr_pages;
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dma_addr_t *dma_addr;
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struct device *dev;
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/* for overlay buffers (pci-pci dma) */
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dma_addr_t bus_addr;
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/* common */
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struct scatterlist *sglist;
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int sglen;
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unsigned long nr_pages;
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int direction;
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};
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struct videobuf_dma_sg_memory {
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u32 magic;
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/* for mmap'ed buffers */
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struct videobuf_dmabuf dma;
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};
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/*
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* Scatter-gather DMA buffer API.
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*
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* These functions provide a simple way to create a page list and a
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* scatter-gather list from a kernel, userspace of physical address and map the
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* memory for DMA operation.
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*
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* Despite the name, this is totally unrelated to videobuf, except that
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* videobuf-dma-sg uses the same API internally.
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*/
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int videobuf_dma_free(struct videobuf_dmabuf *dma);
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int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
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struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
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void *videobuf_sg_alloc(size_t size);
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void videobuf_queue_sg_init(struct videobuf_queue *q,
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const struct videobuf_queue_ops *ops,
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struct device *dev,
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spinlock_t *irqlock,
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enum v4l2_buf_type type,
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enum v4l2_field field,
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unsigned int msize,
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void *priv,
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struct mutex *ext_lock);
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#endif /* _VIDEOBUF_DMA_SG_H */
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