[media] media: videobuf2: Move vb2_fileio_data and vb2_thread to core part

[deliverable/linux.git] / include / media / videobuf2-core.h

/*
 * videobuf2-core.h - Video Buffer 2 Core Framework
 *
 * Copyright (C) 2010 Samsung Electronics
 *
 * Author: Pawel Osciak <pawel@osciak.com>
 *
 * 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.
 */
#ifndef _MEDIA_VIDEOBUF2_CORE_H
#define _MEDIA_VIDEOBUF2_CORE_H

#include <linux/mm_types.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/dma-buf.h>

#define VB2_MAX_FRAME   (32)
#define VB2_MAX_PLANES  (8)

enum vb2_memory {
        VB2_MEMORY_UNKNOWN      = 0,
        VB2_MEMORY_MMAP         = 1,
        VB2_MEMORY_USERPTR      = 2,
        VB2_MEMORY_DMABUF       = 4,
};

struct vb2_alloc_ctx;
struct vb2_fileio_data;
struct vb2_threadio_data;

/**
 * struct vb2_mem_ops - memory handling/memory allocator operations
 * @alloc:      allocate video memory and, optionally, allocator private data,
 *              return NULL on failure or a pointer to allocator private,
 *              per-buffer data on success; the returned private structure
 *              will then be passed as buf_priv argument to other ops in this
 *              structure. Additional gfp_flags to use when allocating the
 *              are also passed to this operation. These flags are from the
 *              gfp_flags field of vb2_queue.
 * @put:        inform the allocator that the buffer will no longer be used;
 *              usually will result in the allocator freeing the buffer (if
 *              no other users of this buffer are present); the buf_priv
 *              argument is the allocator private per-buffer structure
 *              previously returned from the alloc callback.
 * @get_dmabuf: acquire userspace memory for a hardware operation; used for
 *               DMABUF memory types.
 * @get_userptr: acquire userspace memory for a hardware operation; used for
 *               USERPTR memory types; vaddr is the address passed to the
 *               videobuf layer when queuing a video buffer of USERPTR type;
 *               should return an allocator private per-buffer structure
 *               associated with the buffer on success, NULL on failure;
 *               the returned private structure will then be passed as buf_priv
 *               argument to other ops in this structure.
 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 *               be used.
 * @attach_dmabuf: attach a shared struct dma_buf for a hardware operation;
 *                 used for DMABUF memory types; alloc_ctx is the alloc context
 *                 dbuf is the shared dma_buf; returns NULL on failure;
 *                 allocator private per-buffer structure on success;
 *                 this needs to be used for further accesses to the buffer.
 * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
 *                 buffer is no longer used; the buf_priv argument is the
 *                 allocator private per-buffer structure previously returned
 *                 from the attach_dmabuf callback.
 * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
 *              of dmabuf is informed that this driver is going to use the
 *              dmabuf.
 * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
 *                that this driver is done using the dmabuf for now.
 * @prepare:    called every time the buffer is passed from userspace to the
 *              driver, useful for cache synchronisation, optional.
 * @finish:     called every time the buffer is passed back from the driver
 *              to the userspace, also optional.
 * @vaddr:      return a kernel virtual address to a given memory buffer
 *              associated with the passed private structure or NULL if no
 *              such mapping exists.
 * @cookie:     return allocator specific cookie for a given memory buffer
 *              associated with the passed private structure or NULL if not
 *              available.
 * @num_users:  return the current number of users of a memory buffer;
 *              return 1 if the videobuf layer (or actually the driver using
 *              it) is the only user.
 * @mmap:       setup a userspace mapping for a given memory buffer under
 *              the provided virtual memory region.
 *
 * Required ops for USERPTR types: get_userptr, put_userptr.
 * Required ops for MMAP types: alloc, put, num_users, mmap.
 * Required ops for read/write access types: alloc, put, num_users, vaddr.
 * Required ops for DMABUF types: attach_dmabuf, detach_dmabuf, map_dmabuf,
 *                                unmap_dmabuf.
 */
struct vb2_mem_ops {
        void            *(*alloc)(void *alloc_ctx, unsigned long size,
                                  enum dma_data_direction dma_dir,
                                  gfp_t gfp_flags);
        void            (*put)(void *buf_priv);
        struct dma_buf *(*get_dmabuf)(void *buf_priv, unsigned long flags);

        void            *(*get_userptr)(void *alloc_ctx, unsigned long vaddr,
                                        unsigned long size,
                                        enum dma_data_direction dma_dir);
        void            (*put_userptr)(void *buf_priv);

        void            (*prepare)(void *buf_priv);
        void            (*finish)(void *buf_priv);

        void            *(*attach_dmabuf)(void *alloc_ctx, struct dma_buf *dbuf,
                                          unsigned long size,
                                          enum dma_data_direction dma_dir);
        void            (*detach_dmabuf)(void *buf_priv);
        int             (*map_dmabuf)(void *buf_priv);
        void            (*unmap_dmabuf)(void *buf_priv);

        void            *(*vaddr)(void *buf_priv);
        void            *(*cookie)(void *buf_priv);

        unsigned int    (*num_users)(void *buf_priv);

        int             (*mmap)(void *buf_priv, struct vm_area_struct *vma);
};

/**
 * struct vb2_plane - plane information
 * @mem_priv:   private data with this plane
 * @dbuf:       dma_buf - shared buffer object
 * @dbuf_mapped:        flag to show whether dbuf is mapped or not
 * @bytesused:  number of bytes occupied by data in the plane (payload)
 * @length:     size of this plane (NOT the payload) in bytes
 * @offset:     when memory in the associated struct vb2_buffer is
 *              VB2_MEMORY_MMAP, equals the offset from the start of
 *              the device memory for this plane (or is a "cookie" that
 *              should be passed to mmap() called on the video node)
 * @userptr:    when memory is VB2_MEMORY_USERPTR, a userspace pointer
 *              pointing to this plane
 * @fd:         when memory is VB2_MEMORY_DMABUF, a userspace file
 *              descriptor associated with this plane
 * @m:          Union with memtype-specific data (@offset, @userptr or
 *              @fd).
 * @data_offset:        offset in the plane to the start of data; usually 0,
 *              unless there is a header in front of the data
 * Should contain enough information to be able to cover all the fields
 * of struct v4l2_plane at videodev2.h
 */
struct vb2_plane {
        void                    *mem_priv;
        struct dma_buf          *dbuf;
        unsigned int            dbuf_mapped;
        unsigned int            bytesused;
        unsigned int            length;
        union {
                unsigned int    offset;
                unsigned long   userptr;
                int             fd;
        } m;
        unsigned int            data_offset;
};

/**
 * enum vb2_io_modes - queue access methods
 * @VB2_MMAP:           driver supports MMAP with streaming API
 * @VB2_USERPTR:        driver supports USERPTR with streaming API
 * @VB2_READ:           driver supports read() style access
 * @VB2_WRITE:          driver supports write() style access
 * @VB2_DMABUF:         driver supports DMABUF with streaming API
 */
enum vb2_io_modes {
        VB2_MMAP        = (1 << 0),
        VB2_USERPTR     = (1 << 1),
        VB2_READ        = (1 << 2),
        VB2_WRITE       = (1 << 3),
        VB2_DMABUF      = (1 << 4),
};

/**
 * enum vb2_buffer_state - current video buffer state
 * @VB2_BUF_STATE_DEQUEUED:     buffer under userspace control
 * @VB2_BUF_STATE_PREPARING:    buffer is being prepared in videobuf
 * @VB2_BUF_STATE_PREPARED:     buffer prepared in videobuf and by the driver
 * @VB2_BUF_STATE_QUEUED:       buffer queued in videobuf, but not in driver
 * @VB2_BUF_STATE_REQUEUEING:   re-queue a buffer to the driver
 * @VB2_BUF_STATE_ACTIVE:       buffer queued in driver and possibly used
 *                              in a hardware operation
 * @VB2_BUF_STATE_DONE:         buffer returned from driver to videobuf, but
 *                              not yet dequeued to userspace
 * @VB2_BUF_STATE_ERROR:        same as above, but the operation on the buffer
 *                              has ended with an error, which will be reported
 *                              to the userspace when it is dequeued
 */
enum vb2_buffer_state {
        VB2_BUF_STATE_DEQUEUED,
        VB2_BUF_STATE_PREPARING,
        VB2_BUF_STATE_PREPARED,
        VB2_BUF_STATE_QUEUED,
        VB2_BUF_STATE_REQUEUEING,
        VB2_BUF_STATE_ACTIVE,
        VB2_BUF_STATE_DONE,
        VB2_BUF_STATE_ERROR,
};

struct vb2_queue;

/**
 * struct vb2_buffer - represents a video buffer
 * @vb2_queue:          the queue to which this driver belongs
 * @index:              id number of the buffer
 * @type:               buffer type
 * @memory:             the method, in which the actual data is passed
 * @num_planes:         number of planes in the buffer
 *                      on an internal driver queue
 * @planes:             private per-plane information; do not change
 * @timestamp:          frame timestamp in ns
 */
struct vb2_buffer {
        struct vb2_queue        *vb2_queue;
        unsigned int            index;
        unsigned int            type;
        unsigned int            memory;
        unsigned int            num_planes;
        struct vb2_plane        planes[VB2_MAX_PLANES];
        u64                     timestamp;

        /* private: internal use only
         *
         * state:               current buffer state; do not change
         * queued_entry:        entry on the queued buffers list, which holds
         *                      all buffers queued from userspace
         * done_entry:          entry on the list that stores all buffers ready
         *                      to be dequeued to userspace
         */
        enum vb2_buffer_state   state;

        struct list_head        queued_entry;
        struct list_head        done_entry;
#ifdef CONFIG_VIDEO_ADV_DEBUG
        /*
         * Counters for how often these buffer-related ops are
         * called. Used to check for unbalanced ops.
         */
        u32             cnt_mem_alloc;
        u32             cnt_mem_put;
        u32             cnt_mem_get_dmabuf;
        u32             cnt_mem_get_userptr;
        u32             cnt_mem_put_userptr;
        u32             cnt_mem_prepare;
        u32             cnt_mem_finish;
        u32             cnt_mem_attach_dmabuf;
        u32             cnt_mem_detach_dmabuf;
        u32             cnt_mem_map_dmabuf;
        u32             cnt_mem_unmap_dmabuf;
        u32             cnt_mem_vaddr;
        u32             cnt_mem_cookie;
        u32             cnt_mem_num_users;
        u32             cnt_mem_mmap;

        u32             cnt_buf_init;
        u32             cnt_buf_prepare;
        u32             cnt_buf_finish;
        u32             cnt_buf_cleanup;
        u32             cnt_buf_queue;

        /* This counts the number of calls to vb2_buffer_done() */
        u32             cnt_buf_done;
#endif
};

/**
 * struct vb2_ops - driver-specific callbacks
 *
 * @queue_setup:        called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS
 *                      handlers before memory allocation. It can be called
 *                      twice: if the original number of requested buffers
 *                      could not be allocated, then it will be called a
 *                      second time with the actually allocated number of
 *                      buffers to verify if that is OK.
 *                      The driver should return the required number of buffers
 *                      in *num_buffers, the required number of planes per
 *                      buffer in *num_planes, the size of each plane should be
 *                      set in the sizes[] array and optional per-plane
 *                      allocator specific context in the alloc_ctxs[] array.
 *                      When called from VIDIOC_REQBUFS, *num_planes == 0, the
 *                      driver has to use the currently configured format to
 *                      determine the plane sizes and *num_buffers is the total
 *                      number of buffers that are being allocated. When called
 *                      from VIDIOC_CREATE_BUFS, *num_planes != 0 and it
 *                      describes the requested number of planes and sizes[]
 *                      contains the requested plane sizes. If either
 *                      *num_planes or the requested sizes are invalid callback
 *                      must return -EINVAL. In this case *num_buffers are
 *                      being allocated additionally to q->num_buffers.
 * @wait_prepare:       release any locks taken while calling vb2 functions;
 *                      it is called before an ioctl needs to wait for a new
 *                      buffer to arrive; required to avoid a deadlock in
 *                      blocking access type.
 * @wait_finish:        reacquire all locks released in the previous callback;
 *                      required to continue operation after sleeping while
 *                      waiting for a new buffer to arrive.
 * @buf_init:           called once after allocating a buffer (in MMAP case)
 *                      or after acquiring a new USERPTR buffer; drivers may
 *                      perform additional buffer-related initialization;
 *                      initialization failure (return != 0) will prevent
 *                      queue setup from completing successfully; optional.
 * @buf_prepare:        called every time the buffer is queued from userspace
 *                      and from the VIDIOC_PREPARE_BUF ioctl; drivers may
 *                      perform any initialization required before each
 *                      hardware operation in this callback; drivers can
 *                      access/modify the buffer here as it is still synced for
 *                      the CPU; drivers that support VIDIOC_CREATE_BUFS must
 *                      also validate the buffer size; if an error is returned,
 *                      the buffer will not be queued in driver; optional.
 * @buf_finish:         called before every dequeue of the buffer back to
 *                      userspace; the buffer is synced for the CPU, so drivers
 *                      can access/modify the buffer contents; drivers may
 *                      perform any operations required before userspace
 *                      accesses the buffer; optional. The buffer state can be
 *                      one of the following: DONE and ERROR occur while
 *                      streaming is in progress, and the PREPARED state occurs
 *                      when the queue has been canceled and all pending
 *                      buffers are being returned to their default DEQUEUED
 *                      state. Typically you only have to do something if the
 *                      state is VB2_BUF_STATE_DONE, since in all other cases
 *                      the buffer contents will be ignored anyway.
 * @buf_cleanup:        called once before the buffer is freed; drivers may
 *                      perform any additional cleanup; optional.
 * @start_streaming:    called once to enter 'streaming' state; the driver may
 *                      receive buffers with @buf_queue callback before
 *                      @start_streaming is called; the driver gets the number
 *                      of already queued buffers in count parameter; driver
 *                      can return an error if hardware fails, in that case all
 *                      buffers that have been already given by the @buf_queue
 *                      callback are to be returned by the driver by calling
 *                      @vb2_buffer_done(VB2_BUF_STATE_QUEUED).
 *                      If you need a minimum number of buffers before you can
 *                      start streaming, then set @min_buffers_needed in the
 *                      vb2_queue structure. If that is non-zero then
 *                      start_streaming won't be called until at least that
 *                      many buffers have been queued up by userspace.
 * @stop_streaming:     called when 'streaming' state must be disabled; driver
 *                      should stop any DMA transactions or wait until they
 *                      finish and give back all buffers it got from buf_queue()
 *                      callback by calling @vb2_buffer_done() with either
 *                      VB2_BUF_STATE_DONE or VB2_BUF_STATE_ERROR; may use
 *                      vb2_wait_for_all_buffers() function
 * @buf_queue:          passes buffer vb to the driver; driver may start
 *                      hardware operation on this buffer; driver should give
 *                      the buffer back by calling vb2_buffer_done() function;
 *                      it is allways called after calling STREAMON ioctl;
 *                      might be called before start_streaming callback if user
 *                      pre-queued buffers before calling STREAMON.
 */
struct vb2_ops {
        int (*queue_setup)(struct vb2_queue *q,
                           unsigned int *num_buffers, unsigned int *num_planes,
                           unsigned int sizes[], void *alloc_ctxs[]);

        void (*wait_prepare)(struct vb2_queue *q);
        void (*wait_finish)(struct vb2_queue *q);

        int (*buf_init)(struct vb2_buffer *vb);
        int (*buf_prepare)(struct vb2_buffer *vb);
        void (*buf_finish)(struct vb2_buffer *vb);
        void (*buf_cleanup)(struct vb2_buffer *vb);

        int (*start_streaming)(struct vb2_queue *q, unsigned int count);
        void (*stop_streaming)(struct vb2_queue *q);

        void (*buf_queue)(struct vb2_buffer *vb);
};

struct vb2_buf_ops {
        int (*fill_user_buffer)(struct vb2_buffer *vb, void *pb);
        int (*fill_vb2_buffer)(struct vb2_buffer *vb, const void *pb,
                                struct vb2_plane *planes);
        int (*copy_timestamp)(struct vb2_buffer *vb, const void *pb);
};

/**
 * struct vb2_queue - a videobuf queue
 *
 * @type:       private buffer type whose content is defined by the vb2-core
 *              caller. For example, for V4L2, it should match
 *              the V4L2_BUF_TYPE_* in include/uapi/linux/videodev2.h
 * @io_modes:   supported io methods (see vb2_io_modes enum)
 * @fileio_read_once:           report EOF after reading the first buffer
 * @fileio_write_immediately:   queue buffer after each write() call
 * @allow_zero_bytesused:       allow bytesused == 0 to be passed to the driver
 * @lock:       pointer to a mutex that protects the vb2_queue struct. The
 *              driver can set this to a mutex to let the v4l2 core serialize
 *              the queuing ioctls. If the driver wants to handle locking
 *              itself, then this should be set to NULL. This lock is not used
 *              by the videobuf2 core API.
 * @owner:      The filehandle that 'owns' the buffers, i.e. the filehandle
 *              that called reqbufs, create_buffers or started fileio.
 *              This field is not used by the videobuf2 core API, but it allows
 *              drivers to easily associate an owner filehandle with the queue.
 * @ops:        driver-specific callbacks
 * @mem_ops:    memory allocator specific callbacks
 * @buf_ops:    callbacks to deliver buffer information
 *              between user-space and kernel-space
 * @drv_priv:   driver private data
 * @buf_struct_size: size of the driver-specific buffer structure;
 *              "0" indicates the driver doesn't want to use a custom buffer
 *              structure type. for example, sizeof(struct vb2_v4l2_buffer)
 *              will be used for v4l2.
 * @timestamp_flags: Timestamp flags; V4L2_BUF_FLAG_TIMESTAMP_* and
 *              V4L2_BUF_FLAG_TSTAMP_SRC_*
 * @gfp_flags:  additional gfp flags used when allocating the buffers.
 *              Typically this is 0, but it may be e.g. GFP_DMA or __GFP_DMA32
 *              to force the buffer allocation to a specific memory zone.
 * @min_buffers_needed: the minimum number of buffers needed before
 *              start_streaming() can be called. Used when a DMA engine
 *              cannot be started unless at least this number of buffers
 *              have been queued into the driver.
 */
/*
 * Private elements (won't appear at the DocBook):
 * @mmap_lock:  private mutex used when buffers are allocated/freed/mmapped
 * @memory:     current memory type used
 * @bufs:       videobuf buffer structures
 * @num_buffers: number of allocated/used buffers
 * @queued_list: list of buffers currently queued from userspace
 * @queued_count: number of buffers queued and ready for streaming.
 * @owned_by_drv_count: number of buffers owned by the driver
 * @done_list:  list of buffers ready to be dequeued to userspace
 * @done_lock:  lock to protect done_list list
 * @done_wq:    waitqueue for processes waiting for buffers ready to be dequeued
 * @alloc_ctx:  memory type/allocator-specific contexts for each plane
 * @streaming:  current streaming state
 * @start_streaming_called: start_streaming() was called successfully and we
 *              started streaming.
 * @error:      a fatal error occurred on the queue
 * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
 *              buffers. Only set for capture queues if qbuf has not yet been
 *              called since poll() needs to return POLLERR in that situation.
 * @is_multiplanar: set if buffer type is multiplanar
 * @is_output:  set if buffer type is output
 * @copy_timestamp: set if vb2-core should set timestamps
 * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
 *              last decoded buffer was already dequeued. Set for capture queues
 *              when a buffer with the V4L2_BUF_FLAG_LAST is dequeued.
 * @fileio:     file io emulator internal data, used only if emulator is active
 * @threadio:   thread io internal data, used only if thread is active
 */
struct vb2_queue {
        unsigned int                    type;
        unsigned int                    io_modes;
        unsigned                        fileio_read_once:1;
        unsigned                        fileio_write_immediately:1;
        unsigned                        allow_zero_bytesused:1;

        struct mutex                    *lock;
        void                            *owner;

        const struct vb2_ops            *ops;
        const struct vb2_mem_ops        *mem_ops;
        const struct vb2_buf_ops        *buf_ops;

        void                            *drv_priv;
        unsigned int                    buf_struct_size;
        u32                             timestamp_flags;
        gfp_t                           gfp_flags;
        u32                             min_buffers_needed;

        /* private: internal use only */
        struct mutex                    mmap_lock;
        unsigned int                    memory;
        struct vb2_buffer               *bufs[VB2_MAX_FRAME];
        unsigned int                    num_buffers;

        struct list_head                queued_list;
        unsigned int                    queued_count;

        atomic_t                        owned_by_drv_count;
        struct list_head                done_list;
        spinlock_t                      done_lock;
        wait_queue_head_t               done_wq;

        void                            *alloc_ctx[VB2_MAX_PLANES];
        unsigned int                    plane_sizes[VB2_MAX_PLANES];

        unsigned int                    streaming:1;
        unsigned int                    start_streaming_called:1;
        unsigned int                    error:1;
        unsigned int                    waiting_for_buffers:1;
        unsigned int                    is_multiplanar:1;
        unsigned int                    is_output:1;
        unsigned int                    copy_timestamp:1;
        unsigned int                    last_buffer_dequeued:1;

        struct vb2_fileio_data          *fileio;
        struct vb2_threadio_data        *threadio;

#ifdef CONFIG_VIDEO_ADV_DEBUG
        /*
         * Counters for how often these queue-related ops are
         * called. Used to check for unbalanced ops.
         */
        u32                             cnt_queue_setup;
        u32                             cnt_wait_prepare;
        u32                             cnt_wait_finish;
        u32                             cnt_start_streaming;
        u32                             cnt_stop_streaming;
#endif
};

void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);

void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
void vb2_discard_done(struct vb2_queue *q);
int vb2_wait_for_all_buffers(struct vb2_queue *q);

int vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
                unsigned int *count);
int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
                unsigned int *count, unsigned requested_planes,
                const unsigned int requested_sizes[]);
int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);
int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb);
int vb2_core_dqbuf(struct vb2_queue *q, void *pb, bool nonblocking);

int vb2_core_streamon(struct vb2_queue *q, unsigned int type);
int vb2_core_streamoff(struct vb2_queue *q, unsigned int type);

int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
                unsigned int index, unsigned int plane, unsigned int flags);

int vb2_core_queue_init(struct vb2_queue *q);
void vb2_core_queue_release(struct vb2_queue *q);

void vb2_queue_error(struct vb2_queue *q);

int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
#ifndef CONFIG_MMU
unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
                                    unsigned long addr,
                                    unsigned long len,
                                    unsigned long pgoff,
                                    unsigned long flags);
#endif
unsigned int vb2_core_poll(struct vb2_queue *q, struct file *file,
                poll_table *wait);
size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
                loff_t *ppos, int nonblock);
size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
                loff_t *ppos, int nonblock);

/*
 * vb2_thread_fnc - callback function for use with vb2_thread
 *
 * This is called whenever a buffer is dequeued in the thread.
 */
typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv);

/**
 * vb2_thread_start() - start a thread for the given queue.
 * @q:          videobuf queue
 * @fnc:        callback function
 * @priv:       priv pointer passed to the callback function
 * @thread_name:the name of the thread. This will be prefixed with "vb2-".
 *
 * This starts a thread that will queue and dequeue until an error occurs
 * or @vb2_thread_stop is called.
 *
 * This function should not be used for anything else but the videobuf2-dvb
 * support. If you think you have another good use-case for this, then please
 * contact the linux-media mailinglist first.
 */
int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
                     const char *thread_name);

/**
 * vb2_thread_stop() - stop the thread for the given queue.
 * @q:          videobuf queue
 */
int vb2_thread_stop(struct vb2_queue *q);

/**
 * vb2_is_streaming() - return streaming status of the queue
 * @q:          videobuf queue
 */
static inline bool vb2_is_streaming(struct vb2_queue *q)
{
        return q->streaming;
}

/**
 * vb2_fileio_is_active() - return true if fileio is active.
 * @q:          videobuf queue
 *
 * This returns true if read() or write() is used to stream the data
 * as opposed to stream I/O. This is almost never an important distinction,
 * except in rare cases. One such case is that using read() or write() to
 * stream a format using V4L2_FIELD_ALTERNATE is not allowed since there
 * is no way you can pass the field information of each buffer to/from
 * userspace. A driver that supports this field format should check for
 * this in the queue_setup op and reject it if this function returns true.
 */
static inline bool vb2_fileio_is_active(struct vb2_queue *q)
{
        return q->fileio;
}

/**
 * vb2_is_busy() - return busy status of the queue
 * @q:          videobuf queue
 *
 * This function checks if queue has any buffers allocated.
 */
static inline bool vb2_is_busy(struct vb2_queue *q)
{
        return (q->num_buffers > 0);
}

/**
 * vb2_get_drv_priv() - return driver private data associated with the queue
 * @q:          videobuf queue
 */
static inline void *vb2_get_drv_priv(struct vb2_queue *q)
{
        return q->drv_priv;
}

/**
 * vb2_set_plane_payload() - set bytesused for the plane plane_no
 * @vb:         buffer for which plane payload should be set
 * @plane_no:   plane number for which payload should be set
 * @size:       payload in bytes
 */
static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
                                 unsigned int plane_no, unsigned long size)
{
        if (plane_no < vb->num_planes)
                vb->planes[plane_no].bytesused = size;
}

/**
 * vb2_get_plane_payload() - get bytesused for the plane plane_no
 * @vb:         buffer for which plane payload should be set
 * @plane_no:   plane number for which payload should be set
 */
static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
                                 unsigned int plane_no)
{
        if (plane_no < vb->num_planes)
                return vb->planes[plane_no].bytesused;
        return 0;
}

/**
 * vb2_plane_size() - return plane size in bytes
 * @vb:         buffer for which plane size should be returned
 * @plane_no:   plane number for which size should be returned
 */
static inline unsigned long
vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
{
        if (plane_no < vb->num_planes)
                return vb->planes[plane_no].length;
        return 0;
}

/**
 * vb2_start_streaming_called() - return streaming status of driver
 * @q:          videobuf queue
 */
static inline bool vb2_start_streaming_called(struct vb2_queue *q)
{
        return q->start_streaming_called;
}

/**
 * vb2_clear_last_buffer_dequeued() - clear last buffer dequeued flag of queue
 * @q:          videobuf queue
 */
static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)
{
        q->last_buffer_dequeued = false;
}

/*
 * The following functions are not part of the vb2 core API, but are useful
 * functions for videobuf2-*.
 */
bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb);
int vb2_verify_memory_type(struct vb2_queue *q,
                enum vb2_memory memory, unsigned int type);
#endif /* _MEDIA_VIDEOBUF2_CORE_H */