blob: 1115a256969f0468e6ec079567aa6d32e6c338d5 [file] [log] [blame]
* generic helper functions for video4linux capture buffers, to handle
* memory management and PCI DMA.
* Right now, bttv, saa7134, saa7146 and cx88 use it.
* The functions expect the hardware being able to scatter gatter
* (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.
* device specific map/unmap/sync stuff now are mapped as file operations
* to allow its usage by USB and virtual devices.
* (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 of the License, or
* (at your option) any later version.
#include <linux/videodev2.h>
#include <linux/poll.h>
#define UNSET (-1U)
/* --------------------------------------------------------------------- */
* 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);
struct videobuf_buffer;
struct videobuf_queue;
/* --------------------------------------------------------------------- */
* 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;
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);
/*FIXME: these variants are used only on *-alsa code, where videobuf is
* used without queue
int videobuf_pci_dma_map(struct pci_dev *pci,struct videobuf_dmabuf *dma);
int videobuf_pci_dma_unmap(struct pci_dev *pci,struct videobuf_dmabuf *dma);
/* --------------------------------------------------------------------- */
* A small set of helper functions to manage video4linux buffers.
* struct videobuf_buffer holds the data structures used by the helper
* functions, additionally some commonly used fields for v4l buffers
* (width, height, lists, waitqueue) are in there. That struct should
* be used as first element in the drivers buffer struct.
* about the mmap helpers (videobuf_mmap_*):
* The mmaper function allows to map any subset of contingous buffers.
* This includes one mmap() call for all buffers (which the original
* video4linux API uses) as well as one mmap() for every single buffer
* (which v4l2 uses).
* If there is a valid mapping for a buffer, buffer->baddr/bsize holds
* userspace address + size which can be feeded into the
* videobuf_dma_init_user function listed above.
struct videobuf_mapping {
unsigned int count;
unsigned long start;
unsigned long end;
struct videobuf_queue *q;
enum videobuf_state {
struct videobuf_buffer {
unsigned int i;
u32 magic;
/* info about the buffer */
unsigned int width;
unsigned int height;
unsigned int bytesperline; /* use only if != 0 */
unsigned long size;
unsigned int input;
enum v4l2_field field;
enum videobuf_state state;
struct videobuf_dmabuf dma;
struct list_head stream; /* QBUF/DQBUF list */
/* for mmap'ed buffers */
enum v4l2_memory memory;
size_t boff; /* buffer offset (mmap + overlay) */
size_t bsize; /* buffer size */
unsigned long baddr; /* buffer addr (userland ptr!) */
struct videobuf_mapping *map;
/* touched by irq handler */
struct list_head queue;
wait_queue_head_t done;
unsigned int field_count;
struct timeval ts;
typedef int (vb_map_sg_t)(void *dev,struct scatterlist *sglist,int nr_pages,
int direction);
struct videobuf_queue_ops {
int (*buf_setup)(struct videobuf_queue *q,
unsigned int *count, unsigned int *size);
int (*buf_prepare)(struct videobuf_queue *q,
struct videobuf_buffer *vb,
enum v4l2_field field);
void (*buf_queue)(struct videobuf_queue *q,
struct videobuf_buffer *vb);
void (*buf_release)(struct videobuf_queue *q,
struct videobuf_buffer *vb);
/* Helper operations - device dependent.
* If null, videobuf_init defaults all to PCI handling
vb_map_sg_t *vb_map_sg;
vb_map_sg_t *vb_dma_sync_sg;
vb_map_sg_t *vb_unmap_sg;
struct videobuf_queue {
struct mutex lock;
spinlock_t *irqlock;
void *dev; /* on pci, points to struct pci_dev */
enum v4l2_buf_type type;
unsigned int inputs; /* for V4L2_BUF_FLAG_INPUT */
unsigned int msize;
enum v4l2_field field;
enum v4l2_field last; /* for field=V4L2_FIELD_ALTERNATE */
struct videobuf_buffer *bufs[VIDEO_MAX_FRAME];
struct videobuf_queue_ops *ops;
/* capture via mmap() + ioctl(QBUF/DQBUF) */
unsigned int streaming;
struct list_head stream;
/* capture via read() */
unsigned int reading;
unsigned int read_off;
struct videobuf_buffer *read_buf;
/* driver private data */
void *priv_data;
void* videobuf_alloc(unsigned int size);
int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
int videobuf_iolock(struct videobuf_queue* q, struct videobuf_buffer *vb,
struct v4l2_framebuffer *fbuf);
/* Maps fops to PCI stuff */
void videobuf_queue_pci(struct videobuf_queue* q);
void videobuf_queue_init(struct videobuf_queue *q,
struct videobuf_queue_ops *ops,
void *dev,
spinlock_t *irqlock,
enum v4l2_buf_type type,
enum v4l2_field field,
unsigned int msize,
void *priv);
int videobuf_queue_is_busy(struct videobuf_queue *q);
void videobuf_queue_cancel(struct videobuf_queue *q);
enum v4l2_field videobuf_next_field(struct videobuf_queue *q);
void videobuf_status(struct v4l2_buffer *b, struct videobuf_buffer *vb,
enum v4l2_buf_type type);
int videobuf_reqbufs(struct videobuf_queue *q,
struct v4l2_requestbuffers *req);
int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b);
int videobuf_qbuf(struct videobuf_queue *q,
struct v4l2_buffer *b);
int videobuf_dqbuf(struct videobuf_queue *q,
struct v4l2_buffer *b, int nonblocking);
int videobuf_streamon(struct videobuf_queue *q);
int videobuf_streamoff(struct videobuf_queue *q);
int videobuf_read_start(struct videobuf_queue *q);
void videobuf_read_stop(struct videobuf_queue *q);
ssize_t videobuf_read_stream(struct videobuf_queue *q,
char __user *data, size_t count, loff_t *ppos,
int vbihack, int nonblocking);
ssize_t videobuf_read_one(struct videobuf_queue *q,
char __user *data, size_t count, loff_t *ppos,
int nonblocking);
unsigned int videobuf_poll_stream(struct file *file,
struct videobuf_queue *q,
poll_table *wait);
int videobuf_mmap_setup(struct videobuf_queue *q,
unsigned int bcount, unsigned int bsize,
enum v4l2_memory memory);
int videobuf_mmap_free(struct videobuf_queue *q);
int videobuf_mmap_mapper(struct videobuf_queue *q,
struct vm_area_struct *vma);
/* --------------------------------------------------------------------- */
* Local variables:
* c-basic-offset: 8
* End: