diff options
Diffstat (limited to 'include/media/videobuf2-core.h')
| -rw-r--r-- | include/media/videobuf2-core.h | 380 |
1 files changed, 345 insertions, 35 deletions
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index a4a9a55a0c42..ac5898a55fd9 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -20,6 +20,20 @@ #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, @@ -33,15 +47,15 @@ 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, + * 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 @@ -50,18 +64,18 @@ struct vb2_threadio_data; * 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 @@ -95,11 +109,13 @@ struct vb2_threadio_data; * * #) 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); @@ -112,7 +128,8 @@ struct vb2_mem_ops { 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); @@ -277,7 +294,7 @@ struct vb2_buffer { /** * 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 @@ -288,11 +305,11 @@ struct vb2_buffer { * 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 @@ -311,11 +328,11 @@ struct vb2_buffer { * 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 @@ -339,24 +356,25 @@ struct vb2_buffer { * 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, @@ -378,7 +396,7 @@ struct vb2_ops { }; /** - * 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 @@ -404,7 +422,7 @@ struct vb2_buf_ops { * * @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. @@ -439,12 +457,12 @@ struct vb2_buf_ops { * 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 @@ -457,7 +475,7 @@ struct vb2_buf_ops { * @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 @@ -536,36 +554,286 @@ struct vb2_queue { #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, @@ -573,15 +841,36 @@ unsigned long vb2_get_unmapped_area(struct vb2_queue *q, 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. */ @@ -597,9 +886,11 @@ typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv); * 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); @@ -717,7 +1008,26 @@ static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q) * 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 */ |