blob: dda47f0082e99e1e405d29fa0577a492330ccf6f [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>
/* --------------------------------------------------------------------- */
* Return a scatterlist for some page-aligned vmalloc()'ed memory
* block (NULL on errors). Memory for the scatterlist is allocated
* using kmalloc. The caller must free the memory.
struct scatterlist* videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages);
* Return a scatterlist for a an array of userpages (NULL on errors).
* Memory for the scatterlist is allocated using kmalloc. The caller
* must free the memory.
struct scatterlist* videobuf_pages_to_sg(struct page **pages, int nr_pages,
int offset);
/* --------------------------------------------------------------------- */
* 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/PCI/PCI-DMA-mapping.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;
struct page **pages;
/* for kernel buffers */
void *vmalloc;
/* 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;
void videobuf_dma_init(struct videobuf_dmabuf *dma);
int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
unsigned long data, unsigned long size);
int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
int nr_pages);
int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
dma_addr_t addr, int nr_pages);
int videobuf_dma_free(struct videobuf_dmabuf *dma);
int videobuf_dma_map(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
int videobuf_dma_sync(struct videobuf_queue* q,struct videobuf_dmabuf *dma);
int videobuf_dma_unmap(struct videobuf_queue* q,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,
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);
/*FIXME: these variants are used only on *-alsa code, where videobuf is
* used without queue
int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma);
int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma);