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root/include/media/videobuf-dma-sg.h

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/*
 * 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, <mchehab@infradead.org>
 *
 * Highly based on video-buf written originally by:
 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
 * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
 * (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/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);


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