#define VB2_MAX_FRAME (32)
#define VB2_MAX_PLANES (8)
+/**
+ * enum vb2_memory - type of memory model used to make the buffers visible
+ * on userspace.
+ *
+ * @VB2_MEMORY_UNKNOWN: Buffer status is unknown or it is not used yet on
+ * userspace.
+ * @VB2_MEMORY_MMAP: The buffers are allocated by the Kernel and it is
+ * memory mapped via mmap() ioctl. This model is
+ * also used when the user is using the buffers via
+ * read() or write() system calls.
+ * @VB2_MEMORY_USERPTR: The buffers was allocated in userspace and it is
+ * memory mapped via mmap() ioctl.
+ * @VB2_MEMORY_DMABUF: The buffers are passed to userspace via DMA buffer.
+ */
enum vb2_memory {
VB2_MEMORY_UNKNOWN = 0,
VB2_MEMORY_MMAP = 1,
/**
* 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,
+ * return ERR_PTR() 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
+ * 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
+ * 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
* 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
+ * associated with the buffer on success, ERR_PTR() 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; dev is the alloc device
- * dbuf is the shared dma_buf; returns NULL on failure;
+ * dbuf is the shared dma_buf; returns ERR_PTR() 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
+ * 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
*
* #) 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.
+ * #) Required ops for DMABUF types: attach_dmabuf, detach_dmabuf,
+ * map_dmabuf, unmap_dmabuf.
*/
struct vb2_mem_ops {
void *(*alloc)(struct device *dev, unsigned long attrs,
- unsigned long size, enum dma_data_direction dma_dir,
+ 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 (*prepare)(void *buf_priv);
void (*finish)(void *buf_priv);
- void *(*attach_dmabuf)(struct device *dev, struct dma_buf *dbuf,
+ void *(*attach_dmabuf)(struct device *dev,
+ struct dma_buf *dbuf,
unsigned long size,
enum dma_data_direction dma_dir);
void (*detach_dmabuf)(void *buf_priv);
/**
* struct vb2_ops - driver-specific callbacks
*
- * @queue_setup: called from %VIDIOC_REQBUFS and %VIDIOC_CREATE_BUFS
+ * @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
* buffer in \*num_planes, the size of each plane should be
* set in the sizes\[\] array and optional per-plane
* allocator specific device in the alloc_devs\[\] array.
- * When called from %VIDIOC_REQBUFS, \*num_planes == 0, the
- * driver has to use the currently configured format to
+ * 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
+ * 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
* 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
+ * 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
+ * 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
* 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\(%VB2_BUF_STATE_QUEUED\).
+ * by calling vb2_buffer_done() with %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
+ * @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
+ * 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 %VIDIOC_STREAMON ioctl;
- * might be called before start_streaming callback if user
- * pre-queued buffers before calling %VIDIOC_STREAMON.
+ * it is allways called after calling VIDIOC_STREAMON()
+ * ioctl; might be called before @start_streaming callback
+ * if user pre-queued buffers before calling
+ * VIDIOC_STREAMON().
*/
struct vb2_ops {
int (*queue_setup)(struct vb2_queue *q,
};
/**
- * struct vb2_ops - driver-specific callbacks
+ * struct vb2_buf_ops - driver-specific callbacks
*
* @verify_planes_array: Verify that a given user space structure contains
* enough planes for the buffer. This is called
*
* @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
+ * the types defined on enum &v4l2_buf_type
* @io_modes: supported io methods (see vb2_io_modes enum)
* @dev: device to use for the default allocation context if the driver
* doesn't fill in the @alloc_devs array.
* 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
+ * @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):
+ * Private elements (won't appear at the uAPI book):
* @mmap_lock: private mutex used when buffers are allocated/freed/mmapped
* @memory: current memory type used
* @bufs: videobuf buffer structures
* @done_wq: waitqueue for processes waiting for buffers ready to be dequeued
* @alloc_devs: memory type/allocator-specific per-plane device
* @streaming: current streaming state
- * @start_streaming_called: start_streaming() was called successfully and we
+ * @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
#endif
};
+/**
+ * vb2_plane_vaddr() - Return a kernel virtual address of a given plane
+ * @vb: vb2_buffer to which the plane in question belongs to
+ * @plane_no: plane number for which the address is to be returned
+ *
+ * This function returns a kernel virtual address of a given plane if
+ * such a mapping exist, NULL otherwise.
+ */
void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
+
+/**
+ * vb2_plane_cookie() - Return allocator specific cookie for the given plane
+ * @vb: vb2_buffer to which the plane in question belongs to
+ * @plane_no: plane number for which the cookie is to be returned
+ *
+ * This function returns an allocator specific cookie for a given plane if
+ * available, NULL otherwise. The allocator should provide some simple static
+ * inline function, which would convert this cookie to the allocator specific
+ * type that can be used directly by the driver to access the buffer. This can
+ * be for example physical address, pointer to scatter list or IOMMU mapping.
+ */
void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
+/**
+ * vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
+ * @vb: vb2_buffer returned from the driver
+ * @state: either %VB2_BUF_STATE_DONE if the operation finished
+ * successfully, %VB2_BUF_STATE_ERROR if the operation finished
+ * with an error or %VB2_BUF_STATE_QUEUED if the driver wants to
+ * requeue buffers. If start_streaming fails then it should return
+ * buffers with state %VB2_BUF_STATE_QUEUED to put them back into
+ * the queue.
+ *
+ * This function should be called by the driver after a hardware operation on
+ * a buffer is finished and the buffer may be returned to userspace. The driver
+ * cannot use this buffer anymore until it is queued back to it by videobuf
+ * by the means of &vb2_ops->buf_queue callback. Only buffers previously queued
+ * to the driver by &vb2_ops->buf_queue can be passed to this function.
+ *
+ * While streaming a buffer can only be returned in state DONE or ERROR.
+ * The start_streaming op can also return them in case the DMA engine cannot
+ * be started for some reason. In that case the buffers should be returned with
+ * state QUEUED.
+ */
void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
+
+/**
+ * vb2_discard_done() - discard all buffers marked as DONE
+ * @q: videobuf2 queue
+ *
+ * This function is intended to be used with suspend/resume operations. It
+ * discards all 'done' buffers as they would be too old to be requested after
+ * resume.
+ *
+ * Drivers must stop the hardware and synchronize with interrupt handlers and/or
+ * delayed works before calling this function to make sure no buffer will be
+ * touched by the driver and/or hardware.
+ */
void vb2_discard_done(struct vb2_queue *q);
+
+/**
+ * vb2_wait_for_all_buffers() - wait until all buffers are given back to vb2
+ * @q: videobuf2 queue
+ *
+ * This function will wait until all buffers that have been given to the driver
+ * by &vb2_ops->buf_queue are given back to vb2 with vb2_buffer_done(). It
+ * doesn't call wait_prepare()/wait_finish() pair. It is intended to be called
+ * with all locks taken, for example from &vb2_ops->stop_streaming callback.
+ */
int vb2_wait_for_all_buffers(struct vb2_queue *q);
+/**
+ * vb2_core_querybuf() - query video buffer information
+ * @q: videobuf queue
+ * @index: id number of the buffer
+ * @pb: buffer struct passed from userspace
+ *
+ * Should be called from vidioc_querybuf ioctl handler in driver.
+ * The passed buffer should have been verified.
+ * This function fills the relevant information for the userspace.
+ */
void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb);
+
+/**
+ * vb2_core_reqbufs() - Initiate streaming
+ * @q: videobuf2 queue
+ * @memory: memory type
+ * @count: requested buffer count
+ *
+ * Should be called from vidioc_reqbufs ioctl handler of a driver.
+ *
+ * This function:
+ *
+ * #) verifies streaming parameters passed from the userspace,
+ * #) sets up the queue,
+ * #) negotiates number of buffers and planes per buffer with the driver
+ * to be used during streaming,
+ * #) allocates internal buffer structures (struct vb2_buffer), according to
+ * the agreed parameters,
+ * #) for MMAP memory type, allocates actual video memory, using the
+ * memory handling/allocation routines provided during queue initialization
+ *
+ * If req->count is 0, all the memory will be freed instead.
+ * If the queue has been allocated previously (by a previous vb2_reqbufs) call
+ * and the queue is not busy, memory will be reallocated.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_reqbufs handler in driver.
+ */
int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned int *count);
+
+/**
+ * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs
+ * @q: videobuf2 queue
+ * @memory: memory type
+ * @count: requested buffer count
+ * @requested_planes: number of planes requested
+ * @requested_sizes: array with the size of the planes
+ *
+ * Should be called from VIDIOC_CREATE_BUFS() ioctl handler of a driver.
+ * This function:
+ *
+ * #) verifies parameter sanity
+ * #) calls the .queue_setup() queue operation
+ * #) performs any necessary memory allocations
+ *
+ * Return: the return values from this function are intended to be directly
+ * returned from VIDIOC_CREATE_BUFS() handler in driver.
+ */
int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
- unsigned int *count, unsigned requested_planes,
- const unsigned int requested_sizes[]);
+ unsigned int *count, unsigned int requested_planes,
+ const unsigned int requested_sizes[]);
+
+/**
+ * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace
+ * to the kernel
+ * @q: videobuf2 queue
+ * @index: id number of the buffer
+ * @pb: buffer structure passed from userspace to vidioc_prepare_buf
+ * handler in driver
+ *
+ * Should be called from vidioc_prepare_buf ioctl handler of a driver.
+ * The passed buffer should have been verified.
+ * This function calls buf_prepare callback in the driver (if provided),
+ * in which driver-specific buffer initialization can be performed,
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_prepare_buf handler in driver.
+ */
int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb);
+
+/**
+ * vb2_core_qbuf() - Queue a buffer from userspace
+ *
+ * @q: videobuf2 queue
+ * @index: id number of the buffer
+ * @pb: buffer structure passed from userspace to vidioc_qbuf handler
+ * in driver
+ *
+ * Should be called from vidioc_qbuf ioctl handler of a driver.
+ * The passed buffer should have been verified.
+ *
+ * This function:
+ *
+ * #) if necessary, calls buf_prepare callback in the driver (if provided), in
+ * which driver-specific buffer initialization can be performed,
+ * #) if streaming is on, queues the buffer in driver by the means of
+ * &vb2_ops->buf_queue callback for processing.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_qbuf handler in driver.
+ */
int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb);
+
+/**
+ * vb2_core_dqbuf() - Dequeue a buffer to the userspace
+ * @q: videobuf2 queue
+ * @pindex: pointer to the buffer index. May be NULL
+ * @pb: buffer structure passed from userspace to vidioc_dqbuf handler
+ * in driver
+ * @nonblocking: if true, this call will not sleep waiting for a buffer if no
+ * buffers ready for dequeuing are present. Normally the driver
+ * would be passing (file->f_flags & O_NONBLOCK) here
+ *
+ * Should be called from vidioc_dqbuf ioctl handler of a driver.
+ * The passed buffer should have been verified.
+ *
+ * This function:
+ *
+ * #) calls buf_finish callback in the driver (if provided), in which
+ * driver can perform any additional operations that may be required before
+ * returning the buffer to userspace, such as cache sync,
+ * #) the buffer struct members are filled with relevant information for
+ * the userspace.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_dqbuf handler in driver.
+ */
int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, 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);
+/**
+ * vb2_core_expbuf() - Export a buffer as a file descriptor
+ * @q: videobuf2 queue
+ * @fd: file descriptor associated with DMABUF (set by driver) *
+ * @type: buffer type
+ * @index: id number of the buffer
+ * @plane: index of the plane to be exported, 0 for single plane queues
+ * @flags: flags for newly created file, currently only O_CLOEXEC is
+ * supported, refer to manual of open syscall for more details
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_expbuf handler in driver.
+ */
int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
unsigned int index, unsigned int plane, unsigned int flags);
+/**
+ * vb2_core_queue_init() - initialize a videobuf2 queue
+ * @q: videobuf2 queue; this structure should be allocated in driver
+ *
+ * The vb2_queue structure should be allocated by the driver. The driver is
+ * responsible of clearing it's content and setting initial values for some
+ * required entries before calling this function.
+ * q->ops, q->mem_ops, q->type and q->io_modes are mandatory. Please refer
+ * to the struct vb2_queue description in include/media/videobuf2-core.h
+ * for more information.
+ */
int vb2_core_queue_init(struct vb2_queue *q);
+
+/**
+ * vb2_core_queue_release() - stop streaming, release the queue and free memory
+ * @q: videobuf2 queue
+ *
+ * This function stops streaming and performs necessary clean ups, including
+ * freeing video buffer memory. The driver is responsible for freeing
+ * the vb2_queue structure itself.
+ */
void vb2_core_queue_release(struct vb2_queue *q);
+/**
+ * vb2_queue_error() - signal a fatal error on the queue
+ * @q: videobuf2 queue
+ *
+ * Flag that a fatal unrecoverable error has occurred and wake up all processes
+ * waiting on the queue. Polling will now set POLLERR and queuing and dequeuing
+ * buffers will return -EIO.
+ *
+ * The error flag will be cleared when cancelling the queue, either from
+ * vb2_streamoff or vb2_queue_release. Drivers should thus not call this
+ * function before starting the stream, otherwise the error flag will remain set
+ * until the queue is released when closing the device node.
+ */
void vb2_queue_error(struct vb2_queue *q);
+/**
+ * vb2_mmap() - map video buffers into application address space
+ * @q: videobuf2 queue
+ * @vma: vma passed to the mmap file operation handler in the driver
+ *
+ * Should be called from mmap file operation handler of a driver.
+ * This function maps one plane of one of the available video buffers to
+ * userspace. To map whole video memory allocated on reqbufs, this function
+ * has to be called once per each plane per each buffer previously allocated.
+ *
+ * When the userspace application calls mmap, it passes to it an offset returned
+ * to it earlier by the means of vidioc_querybuf handler. That offset acts as
+ * a "cookie", which is then used to identify the plane to be mapped.
+ * This function finds a plane with a matching offset and a mapping is performed
+ * by the means of a provided memory operation.
+ *
+ * The return values from this function are intended to be directly returned
+ * from the mmap handler in driver.
+ */
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 pgoff,
unsigned long flags);
#endif
+
+/**
+ * vb2_core_poll() - implements poll userspace operation
+ * @q: videobuf2 queue
+ * @file: file argument passed to the poll file operation handler
+ * @wait: wait argument passed to the poll file operation handler
+ *
+ * This function implements poll file operation handler for a driver.
+ * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
+ * be informed that the file descriptor of a video device is available for
+ * reading.
+ * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
+ * will be reported as available for writing.
+ *
+ * The return values from this function are intended to be directly returned
+ * from poll handler in driver.
+ */
unsigned int vb2_core_poll(struct vb2_queue *q, struct file *file,
- poll_table *wait);
+ 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
+/**
+ * typedef vb2_thread_fnc - callback function for use with vb2_thread
+ *
+ * @vb: pointer to struct &vb2_buffer
+ * @priv: pointer to a private pointer
*
* This is called whenever a buffer is dequeued in the thread.
*/
* 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.
+ * .. attention::
+ *
+ * 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 mailing list first.
*/
int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
const char *thread_name);
* The following functions are not part of the vb2 core API, but are useful
* functions for videobuf2-*.
*/
+
+/**
+ * vb2_buffer_in_use() - return true if the buffer is in use and
+ * the queue cannot be freed (by the means of REQBUFS(0)) call
+ *
+ * @vb: buffer for which plane size should be returned
+ * @q: videobuf queue
+ */
bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb);
+
+/**
+ * vb2_verify_memory_type() - Check whether the memory type and buffer type
+ * passed to a buffer operation are compatible with the queue.
+ *
+ * @q: videobuf queue
+ * @memory: memory model, as defined by enum &vb2_memory.
+ * @type: private buffer type whose content is defined by the vb2-core
+ * caller. For example, for V4L2, it should match
+ * the types defined on enum &v4l2_buf_type
+ */
int vb2_verify_memory_type(struct vb2_queue *q,
enum vb2_memory memory, unsigned int type);
#endif /* _MEDIA_VIDEOBUF2_CORE_H */
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