blob: 01bd142b979d82a438aece21d8f632defc01eb0a [file] [log] [blame]
* helper functions for SG DMA video4linux capture buffers
* The functions expect the hardware being able to scatter gather
* (i.e. the buffers are not linear in physical memory, but fragmented
* into PAGE_SIZE chunks). They also assume the driver does not need
* to touch the video data.
* (c) 2007 Mauro Carvalho Chehab, <>
* Highly based on video-buf written originally by:
* (c) 2001,02 Gerd Knorr <>
* (c) 2006 Mauro Carvalho Chehab, <>
* (c) 2006 Ted Walther and John Sokol
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2
#include <media/videobuf-core.h>
/* --------------------------------------------------------------------- */
* A small set of helper functions to manage buffers (both userland
* and kernel) for DMA.
* videobuf_dma_init_*()
* creates a buffer. The userland version takes a userspace
* pointer + length. The kernel version just wants the size and
* does memory allocation too using vmalloc_32().
* videobuf_dma_*()
* see Documentation/DMA-API-HOWTO.txt, these functions to
* basically the same. The map function does also build a
* scatterlist for the buffer (and unmap frees it ...)
* videobuf_dma_free()
* no comment ...
struct videobuf_dmabuf {
u32 magic;
/* for userland buffer */
int offset;
size_t size;
struct page **pages;
/* for kernel buffers */
void *vaddr;
struct page **vaddr_pages;
dma_addr_t *dma_addr;
struct device *dev;
/* for overlay buffers (pci-pci dma) */
dma_addr_t bus_addr;
/* common */
struct scatterlist *sglist;
int sglen;
int nr_pages;
int direction;
struct videobuf_dma_sg_memory {
u32 magic;
/* for mmap'ed buffers */
struct videobuf_dmabuf dma;
* Scatter-gather DMA buffer API.
* These functions provide a simple way to create a page list and a
* scatter-gather list from a kernel, userspace of physical address and map the
* memory for DMA operation.
* Despite the name, this is totally unrelated to videobuf, except that
* videobuf-dma-sg uses the same API internally.
int videobuf_dma_free(struct videobuf_dmabuf *dma);
int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);
struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf);
void *videobuf_sg_alloc(size_t size);
void videobuf_queue_sg_init(struct videobuf_queue *q,
const struct videobuf_queue_ops *ops,
struct device *dev,
spinlock_t *irqlock,
enum v4l2_buf_type type,
enum v4l2_field field,
unsigned int msize,
void *priv,
struct mutex *ext_lock);
#endif /* _VIDEOBUF_DMA_SG_H */