1/*
   2 * videobuf2-core.h - Video Buffer 2 Core Framework
   3 *
   4 * Copyright (C) 2010 Samsung Electronics
   5 *
   6 * Author: Pawel Osciak <pawel@osciak.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as published by
  10 * the Free Software Foundation.
  11 */
  12#ifndef _MEDIA_VIDEOBUF2_CORE_H
  13#define _MEDIA_VIDEOBUF2_CORE_H
  14
  15#include <linux/mm_types.h>
  16#include <linux/mutex.h>
  17#include <linux/poll.h>
  18#include <linux/dma-buf.h>
  19#include <linux/bitops.h>
  20#include <media/media-request.h>
  21#include <media/frame_vector.h>
  22
  23#define VB2_MAX_FRAME	(32)
  24#define VB2_MAX_PLANES	(8)
  25
  26/**
  27 * enum vb2_memory - type of memory model used to make the buffers visible
  28 *	on userspace.
  29 *
  30 * @VB2_MEMORY_UNKNOWN:	Buffer status is unknown or it is not used yet on
  31 *			userspace.
  32 * @VB2_MEMORY_MMAP:	The buffers are allocated by the Kernel and it is
  33 *			memory mapped via mmap() ioctl. This model is
  34 *			also used when the user is using the buffers via
  35 *			read() or write() system calls.
  36 * @VB2_MEMORY_USERPTR:	The buffers was allocated in userspace and it is
  37 *			memory mapped via mmap() ioctl.
  38 * @VB2_MEMORY_DMABUF:	The buffers are passed to userspace via DMA buffer.
  39 */
  40enum vb2_memory {
  41	VB2_MEMORY_UNKNOWN	= 0,
  42	VB2_MEMORY_MMAP		= 1,
  43	VB2_MEMORY_USERPTR	= 2,
  44	VB2_MEMORY_DMABUF	= 4,
  45};
  46
 
  47struct vb2_fileio_data;
  48struct vb2_threadio_data;
  49struct vb2_buffer;
  50
  51/**
  52 * struct vb2_mem_ops - memory handling/memory allocator operations.
  53 * @alloc:	allocate video memory and, optionally, allocator private data,
  54 *		return ERR_PTR() on failure or a pointer to allocator private,
  55 *		per-buffer data on success; the returned private structure
  56 *		will then be passed as @buf_priv argument to other ops in this
  57 *		structure. The size argument to this function shall be
  58 *		*page aligned*.
 
  59 * @put:	inform the allocator that the buffer will no longer be used;
  60 *		usually will result in the allocator freeing the buffer (if
  61 *		no other users of this buffer are present); the @buf_priv
  62 *		argument is the allocator private per-buffer structure
  63 *		previously returned from the alloc callback.
  64 * @get_dmabuf: acquire userspace memory for a hardware operation; used for
  65 *		 DMABUF memory types.
  66 * @get_userptr: acquire userspace memory for a hardware operation; used for
  67 *		 USERPTR memory types; vaddr is the address passed to the
  68 *		 videobuf2 layer when queuing a video buffer of USERPTR type;
  69 *		 should return an allocator private per-buffer structure
  70 *		 associated with the buffer on success, ERR_PTR() on failure;
  71 *		 the returned private structure will then be passed as @buf_priv
  72 *		 argument to other ops in this structure.
  73 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
  74 *		 be used.
  75 * @prepare:	called every time the buffer is passed from userspace to the
  76 *		driver, useful for cache synchronisation, optional.
  77 * @finish:	called every time the buffer is passed back from the driver
  78 *		to the userspace, also optional.
  79 * @attach_dmabuf: attach a shared &struct dma_buf for a hardware operation;
  80 *		   used for DMABUF memory types; dev is the alloc device
  81 *		   dbuf is the shared dma_buf; returns ERR_PTR() on failure;
  82 *		   allocator private per-buffer structure on success;
  83 *		   this needs to be used for further accesses to the buffer.
  84 * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
  85 *		   buffer is no longer used; the @buf_priv argument is the
  86 *		   allocator private per-buffer structure previously returned
  87 *		   from the attach_dmabuf callback.
  88 * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
  89 *		of dmabuf is informed that this driver is going to use the
  90 *		dmabuf.
  91 * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
  92 *		  that this driver is done using the dmabuf for now.
 
 
 
 
  93 * @vaddr:	return a kernel virtual address to a given memory buffer
  94 *		associated with the passed private structure or NULL if no
  95 *		such mapping exists.
  96 * @cookie:	return allocator specific cookie for a given memory buffer
  97 *		associated with the passed private structure or NULL if not
  98 *		available.
  99 * @num_users:	return the current number of users of a memory buffer;
 100 *		return 1 if the videobuf2 layer (or actually the driver using
 101 *		it) is the only user.
 102 * @mmap:	setup a userspace mapping for a given memory buffer under
 103 *		the provided virtual memory region.
 104 *
 105 * Those operations are used by the videobuf2 core to implement the memory
 106 * handling/memory allocators for each type of supported streaming I/O method.
 107 *
 108 * .. note::
 109 *    #) Required ops for USERPTR types: get_userptr, put_userptr.
 110 *
 111 *    #) Required ops for MMAP types: alloc, put, num_users, mmap.
 112 *
 113 *    #) Required ops for read/write access types: alloc, put, num_users, vaddr.
 114 *
 115 *    #) Required ops for DMABUF types: attach_dmabuf, detach_dmabuf,
 116 *       map_dmabuf, unmap_dmabuf.
 117 */
 118struct vb2_mem_ops {
 119	void		*(*alloc)(struct vb2_buffer *vb,
 120				  struct device *dev,
 121				  unsigned long size);
 122	void		(*put)(void *buf_priv);
 123	struct dma_buf *(*get_dmabuf)(struct vb2_buffer *vb,
 124				      void *buf_priv,
 125				      unsigned long flags);
 126
 127	void		*(*get_userptr)(struct vb2_buffer *vb,
 128					struct device *dev,
 129					unsigned long vaddr,
 130					unsigned long size);
 131	void		(*put_userptr)(void *buf_priv);
 132
 133	void		(*prepare)(void *buf_priv);
 134	void		(*finish)(void *buf_priv);
 135
 136	void		*(*attach_dmabuf)(struct vb2_buffer *vb,
 137					  struct device *dev,
 138					  struct dma_buf *dbuf,
 139					  unsigned long size);
 140	void		(*detach_dmabuf)(void *buf_priv);
 141	int		(*map_dmabuf)(void *buf_priv);
 142	void		(*unmap_dmabuf)(void *buf_priv);
 143
 144	void		*(*vaddr)(struct vb2_buffer *vb, void *buf_priv);
 145	void		*(*cookie)(struct vb2_buffer *vb, void *buf_priv);
 146
 147	unsigned int	(*num_users)(void *buf_priv);
 148
 149	int		(*mmap)(void *buf_priv, struct vm_area_struct *vma);
 150};
 151
 152/**
 153 * struct vb2_plane - plane information.
 154 * @mem_priv:	private data with this plane.
 155 * @dbuf:	dma_buf - shared buffer object.
 156 * @dbuf_mapped:	flag to show whether dbuf is mapped or not
 157 * @dbuf_duplicated:	boolean to show whether dbuf is duplicated with a
 158 *		previous plane of the buffer.
 159 * @bytesused:	number of bytes occupied by data in the plane (payload).
 160 * @length:	size of this plane (NOT the payload) in bytes. The maximum
 161 *		valid size is MAX_UINT - PAGE_SIZE.
 162 * @min_length:	minimum required size of this plane (NOT the payload) in bytes.
 163 *		@length is always greater or equal to @min_length, and like
 164 *		@length, it is limited to MAX_UINT - PAGE_SIZE.
 165 * @m:		Union with memtype-specific data.
 166 * @m.offset:	when memory in the associated struct vb2_buffer is
 167 *		%VB2_MEMORY_MMAP, equals the offset from the start of
 168 *		the device memory for this plane (or is a "cookie" that
 169 *		should be passed to mmap() called on the video node).
 170 * @m.userptr:	when memory is %VB2_MEMORY_USERPTR, a userspace pointer
 171 *		pointing to this plane.
 172 * @m.fd:	when memory is %VB2_MEMORY_DMABUF, a userspace file
 173 *		descriptor associated with this plane.
 
 
 174 * @data_offset:	offset in the plane to the start of data; usually 0,
 175 *		unless there is a header in front of the data.
 176 *
 177 * Should contain enough information to be able to cover all the fields
 178 * of &struct v4l2_plane at videodev2.h.
 179 */
 180struct vb2_plane {
 181	void			*mem_priv;
 182	struct dma_buf		*dbuf;
 183	unsigned int		dbuf_mapped;
 184	bool			dbuf_duplicated;
 185	unsigned int		bytesused;
 186	unsigned int		length;
 187	unsigned int		min_length;
 188	union {
 189		unsigned int	offset;
 190		unsigned long	userptr;
 191		int		fd;
 192	} m;
 193	unsigned int		data_offset;
 194};
 195
 196/**
 197 * enum vb2_io_modes - queue access methods.
 198 * @VB2_MMAP:		driver supports MMAP with streaming API.
 199 * @VB2_USERPTR:	driver supports USERPTR with streaming API.
 200 * @VB2_READ:		driver supports read() style access.
 201 * @VB2_WRITE:		driver supports write() style access.
 202 * @VB2_DMABUF:		driver supports DMABUF with streaming API.
 203 */
 204enum vb2_io_modes {
 205	VB2_MMAP	= BIT(0),
 206	VB2_USERPTR	= BIT(1),
 207	VB2_READ	= BIT(2),
 208	VB2_WRITE	= BIT(3),
 209	VB2_DMABUF	= BIT(4),
 210};
 211
 212/**
 213 * enum vb2_buffer_state - current video buffer state.
 214 * @VB2_BUF_STATE_DEQUEUED:	buffer under userspace control.
 215 * @VB2_BUF_STATE_IN_REQUEST:	buffer is queued in media request.
 216 * @VB2_BUF_STATE_PREPARING:	buffer is being prepared in videobuf2.
 217 * @VB2_BUF_STATE_QUEUED:	buffer queued in videobuf2, but not in driver.
 
 218 * @VB2_BUF_STATE_ACTIVE:	buffer queued in driver and possibly used
 219 *				in a hardware operation.
 220 * @VB2_BUF_STATE_DONE:		buffer returned from driver to videobuf2, but
 221 *				not yet dequeued to userspace.
 222 * @VB2_BUF_STATE_ERROR:	same as above, but the operation on the buffer
 223 *				has ended with an error, which will be reported
 224 *				to the userspace when it is dequeued.
 225 */
 226enum vb2_buffer_state {
 227	VB2_BUF_STATE_DEQUEUED,
 228	VB2_BUF_STATE_IN_REQUEST,
 229	VB2_BUF_STATE_PREPARING,
 
 230	VB2_BUF_STATE_QUEUED,
 
 231	VB2_BUF_STATE_ACTIVE,
 232	VB2_BUF_STATE_DONE,
 233	VB2_BUF_STATE_ERROR,
 234};
 235
 236struct vb2_queue;
 237
 238/**
 239 * struct vb2_buffer - represents a video buffer.
 240 * @vb2_queue:		pointer to &struct vb2_queue with the queue to
 241 *			which this driver belongs.
 242 * @index:		id number of the buffer.
 243 * @type:		buffer type.
 244 * @memory:		the method, in which the actual data is passed.
 245 * @num_planes:		number of planes in the buffer
 246 *			on an internal driver queue.
 247 * @timestamp:		frame timestamp in ns.
 248 * @request:		the request this buffer is associated with.
 249 * @req_obj:		used to bind this buffer to a request. This
 250 *			request object has a refcount.
 251 */
 252struct vb2_buffer {
 253	struct vb2_queue	*vb2_queue;
 254	unsigned int		index;
 255	unsigned int		type;
 256	unsigned int		memory;
 257	unsigned int		num_planes;
 
 258	u64			timestamp;
 259	struct media_request	*request;
 260	struct media_request_object	req_obj;
 261
 262	/* private: internal use only
 263	 *
 264	 * state:		current buffer state; do not change
 265	 * synced:		this buffer has been synced for DMA, i.e. the
 266	 *			'prepare' memop was called. It is cleared again
 267	 *			after the 'finish' memop is called.
 268	 * prepared:		this buffer has been prepared, i.e. the
 269	 *			buf_prepare op was called. It is cleared again
 270	 *			after the 'buf_finish' op is called.
 271	 * copied_timestamp:	the timestamp of this capture buffer was copied
 272	 *			from an output buffer.
 273	 * skip_cache_sync_on_prepare: when set buffer's ->prepare() function
 274	 *			skips cache sync/invalidation.
 275	 * skip_cache_sync_on_finish: when set buffer's ->finish() function
 276	 *			skips cache sync/invalidation.
 277	 * planes:		per-plane information; do not change
 278	 * queued_entry:	entry on the queued buffers list, which holds
 279	 *			all buffers queued from userspace
 280	 * done_entry:		entry on the list that stores all buffers ready
 281	 *			to be dequeued to userspace
 282	 */
 283	enum vb2_buffer_state	state;
 284	unsigned int		synced:1;
 285	unsigned int		prepared:1;
 286	unsigned int		copied_timestamp:1;
 287	unsigned int		skip_cache_sync_on_prepare:1;
 288	unsigned int		skip_cache_sync_on_finish:1;
 289
 290	struct vb2_plane	planes[VB2_MAX_PLANES];
 291	struct list_head	queued_entry;
 292	struct list_head	done_entry;
 293#ifdef CONFIG_VIDEO_ADV_DEBUG
 294	/*
 295	 * Counters for how often these buffer-related ops are
 296	 * called. Used to check for unbalanced ops.
 297	 */
 298	u32		cnt_mem_alloc;
 299	u32		cnt_mem_put;
 300	u32		cnt_mem_get_dmabuf;
 301	u32		cnt_mem_get_userptr;
 302	u32		cnt_mem_put_userptr;
 303	u32		cnt_mem_prepare;
 304	u32		cnt_mem_finish;
 305	u32		cnt_mem_attach_dmabuf;
 306	u32		cnt_mem_detach_dmabuf;
 307	u32		cnt_mem_map_dmabuf;
 308	u32		cnt_mem_unmap_dmabuf;
 309	u32		cnt_mem_vaddr;
 310	u32		cnt_mem_cookie;
 311	u32		cnt_mem_num_users;
 312	u32		cnt_mem_mmap;
 313
 314	u32		cnt_buf_out_validate;
 315	u32		cnt_buf_init;
 316	u32		cnt_buf_prepare;
 317	u32		cnt_buf_finish;
 318	u32		cnt_buf_cleanup;
 319	u32		cnt_buf_queue;
 320	u32		cnt_buf_request_complete;
 321
 322	/* This counts the number of calls to vb2_buffer_done() */
 323	u32		cnt_buf_done;
 324#endif
 325};
 326
 327/**
 328 * struct vb2_ops - driver-specific callbacks.
 329 *
 330 * These operations are not called from interrupt context except where
 331 * mentioned specifically.
 332 *
 333 * @queue_setup:	called from VIDIOC_REQBUFS() and VIDIOC_CREATE_BUFS()
 334 *			handlers before memory allocation. It can be called
 335 *			twice: if the original number of requested buffers
 336 *			could not be allocated, then it will be called a
 337 *			second time with the actually allocated number of
 338 *			buffers to verify if that is OK.
 339 *			The driver should return the required number of buffers
 340 *			in \*num_buffers, the required number of planes per
 341 *			buffer in \*num_planes, the size of each plane should be
 342 *			set in the sizes\[\] array and optional per-plane
 343 *			allocator specific device in the alloc_devs\[\] array.
 344 *			When called from VIDIOC_REQBUFS(), \*num_planes == 0,
 345 *			the driver has to use the currently configured format to
 346 *			determine the plane sizes and \*num_buffers is the total
 347 *			number of buffers that are being allocated. When called
 348 *			from VIDIOC_CREATE_BUFS(), \*num_planes != 0 and it
 349 *			describes the requested number of planes and sizes\[\]
 350 *			contains the requested plane sizes. In this case
 351 *			\*num_buffers are being allocated additionally to
 352 *			the buffers already allocated. If either \*num_planes
 353 *			or the requested sizes are invalid callback must return %-EINVAL.
 354 * @wait_prepare:	release any locks taken while calling vb2 functions;
 355 *			it is called before an ioctl needs to wait for a new
 356 *			buffer to arrive; required to avoid a deadlock in
 357 *			blocking access type.
 358 * @wait_finish:	reacquire all locks released in the previous callback;
 359 *			required to continue operation after sleeping while
 360 *			waiting for a new buffer to arrive.
 361 * @buf_out_validate:	called when the output buffer is prepared or queued
 362 *			to a request; drivers can use this to validate
 363 *			userspace-provided information; this is required only
 364 *			for OUTPUT queues.
 365 * @buf_init:		called once after allocating a buffer (in MMAP case)
 366 *			or after acquiring a new USERPTR buffer; drivers may
 367 *			perform additional buffer-related initialization;
 368 *			initialization failure (return != 0) will prevent
 369 *			queue setup from completing successfully; optional.
 370 * @buf_prepare:	called every time the buffer is queued from userspace
 371 *			and from the VIDIOC_PREPARE_BUF() ioctl; drivers may
 372 *			perform any initialization required before each
 373 *			hardware operation in this callback; drivers can
 374 *			access/modify the buffer here as it is still synced for
 375 *			the CPU; drivers that support VIDIOC_CREATE_BUFS() must
 376 *			also validate the buffer size; if an error is returned,
 377 *			the buffer will not be queued in driver; optional.
 378 * @buf_finish:		called before every dequeue of the buffer back to
 379 *			userspace; the buffer is synced for the CPU, so drivers
 380 *			can access/modify the buffer contents; drivers may
 381 *			perform any operations required before userspace
 382 *			accesses the buffer; optional. The buffer state can be
 383 *			one of the following: %DONE and %ERROR occur while
 384 *			streaming is in progress, and the %PREPARED state occurs
 385 *			when the queue has been canceled and all pending
 386 *			buffers are being returned to their default %DEQUEUED
 387 *			state. Typically you only have to do something if the
 388 *			state is %VB2_BUF_STATE_DONE, since in all other cases
 389 *			the buffer contents will be ignored anyway.
 390 * @buf_cleanup:	called once before the buffer is freed; drivers may
 391 *			perform any additional cleanup; optional.
 392 * @prepare_streaming:	called once to prepare for 'streaming' state; this is
 393 *			where validation can be done to verify everything is
 394 *			okay and streaming resources can be claimed. It is
 395 *			called when the VIDIOC_STREAMON ioctl is called. The
 396 *			actual streaming starts when @start_streaming is called.
 397 *			Optional.
 398 * @start_streaming:	called once to enter 'streaming' state; the driver may
 399 *			receive buffers with @buf_queue callback
 400 *			before @start_streaming is called; the driver gets the
 401 *			number of already queued buffers in count parameter;
 402 *			driver can return an error if hardware fails, in that
 403 *			case all buffers that have been already given by
 404 *			the @buf_queue callback are to be returned by the driver
 405 *			by calling vb2_buffer_done() with %VB2_BUF_STATE_QUEUED.
 406 *			If you need a minimum number of buffers before you can
 407 *			start streaming, then set
 408 *			&vb2_queue->min_queued_buffers. If that is non-zero
 409 *			then @start_streaming won't be called until at least
 410 *			that many buffers have been queued up by userspace.
 411 * @stop_streaming:	called when 'streaming' state must be disabled; driver
 412 *			should stop any DMA transactions or wait until they
 413 *			finish and give back all buffers it got from &buf_queue
 414 *			callback by calling vb2_buffer_done() with either
 415 *			%VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use
 416 *			vb2_wait_for_all_buffers() function
 417 * @unprepare_streaming:called as counterpart to @prepare_streaming; any claimed
 418 *			streaming resources can be released here. It is
 419 *			called when the VIDIOC_STREAMOFF ioctls is called or
 420 *			when the streaming filehandle is closed. Optional.
 421 * @buf_queue:		passes buffer vb to the driver; driver may start
 422 *			hardware operation on this buffer; driver should give
 423 *			the buffer back by calling vb2_buffer_done() function;
 424 *			it is always called after calling VIDIOC_STREAMON()
 425 *			ioctl; might be called before @start_streaming callback
 426 *			if user pre-queued buffers before calling
 427 *			VIDIOC_STREAMON().
 428 * @buf_request_complete: a buffer that was never queued to the driver but is
 429 *			associated with a queued request was canceled.
 430 *			The driver will have to mark associated objects in the
 431 *			request as completed; required if requests are
 432 *			supported.
 433 */
 434struct vb2_ops {
 435	int (*queue_setup)(struct vb2_queue *q,
 436			   unsigned int *num_buffers, unsigned int *num_planes,
 437			   unsigned int sizes[], struct device *alloc_devs[]);
 438
 439	void (*wait_prepare)(struct vb2_queue *q);
 440	void (*wait_finish)(struct vb2_queue *q);
 441
 442	int (*buf_out_validate)(struct vb2_buffer *vb);
 443	int (*buf_init)(struct vb2_buffer *vb);
 444	int (*buf_prepare)(struct vb2_buffer *vb);
 445	void (*buf_finish)(struct vb2_buffer *vb);
 446	void (*buf_cleanup)(struct vb2_buffer *vb);
 447
 448	int (*prepare_streaming)(struct vb2_queue *q);
 449	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
 450	void (*stop_streaming)(struct vb2_queue *q);
 451	void (*unprepare_streaming)(struct vb2_queue *q);
 452
 453	void (*buf_queue)(struct vb2_buffer *vb);
 454
 455	void (*buf_request_complete)(struct vb2_buffer *vb);
 456};
 457
 458/**
 459 * struct vb2_buf_ops - driver-specific callbacks.
 460 *
 461 * @verify_planes_array: Verify that a given user space structure contains
 462 *			enough planes for the buffer. This is called
 463 *			for each dequeued buffer.
 464 * @init_buffer:	given a &vb2_buffer initialize the extra data after
 465 *			struct vb2_buffer.
 466 *			For V4L2 this is a &struct vb2_v4l2_buffer.
 467 * @fill_user_buffer:	given a &vb2_buffer fill in the userspace structure.
 468 *			For V4L2 this is a &struct v4l2_buffer.
 469 * @fill_vb2_buffer:	given a userspace structure, fill in the &vb2_buffer.
 470 *			If the userspace structure is invalid, then this op
 471 *			will return an error.
 472 * @copy_timestamp:	copy the timestamp from a userspace structure to
 473 *			the &struct vb2_buffer.
 474 */
 475struct vb2_buf_ops {
 476	int (*verify_planes_array)(struct vb2_buffer *vb, const void *pb);
 477	void (*init_buffer)(struct vb2_buffer *vb);
 478	void (*fill_user_buffer)(struct vb2_buffer *vb, void *pb);
 479	int (*fill_vb2_buffer)(struct vb2_buffer *vb, struct vb2_plane *planes);
 
 480	void (*copy_timestamp)(struct vb2_buffer *vb, const void *pb);
 481};
 482
 483/**
 484 * struct vb2_queue - a videobuf2 queue.
 485 *
 486 * @type:	private buffer type whose content is defined by the vb2-core
 487 *		caller. For example, for V4L2, it should match
 488 *		the types defined on &enum v4l2_buf_type.
 489 * @io_modes:	supported io methods (see &enum vb2_io_modes).
 490 * @dev:	device to use for the default allocation context if the driver
 491 *		doesn't fill in the @alloc_devs array.
 492 * @dma_attrs:	DMA attributes to use for the DMA.
 493 * @bidirectional: when this flag is set the DMA direction for the buffers of
 494 *		this queue will be overridden with %DMA_BIDIRECTIONAL direction.
 495 *		This is useful in cases where the hardware (firmware) writes to
 496 *		a buffer which is mapped as read (%DMA_TO_DEVICE), or reads from
 497 *		buffer which is mapped for write (%DMA_FROM_DEVICE) in order
 498 *		to satisfy some internal hardware restrictions or adds a padding
 499 *		needed by the processing algorithm. In case the DMA mapping is
 500 *		not bidirectional but the hardware (firmware) trying to access
 501 *		the buffer (in the opposite direction) this could lead to an
 502 *		IOMMU protection faults.
 503 * @fileio_read_once:		report EOF after reading the first buffer
 504 * @fileio_write_immediately:	queue buffer after each write() call
 505 * @allow_zero_bytesused:	allow bytesused == 0 to be passed to the driver
 506 * @quirk_poll_must_check_waiting_for_buffers: Return %EPOLLERR at poll when QBUF
 507 *              has not been called. This is a vb1 idiom that has been adopted
 508 *              also by vb2.
 509 * @supports_requests: this queue supports the Request API.
 510 * @requires_requests: this queue requires the Request API. If this is set to 1,
 511 *		then supports_requests must be set to 1 as well.
 512 * @uses_qbuf:	qbuf was used directly for this queue. Set to 1 the first
 513 *		time this is called. Set to 0 when the queue is canceled.
 514 *		If this is 1, then you cannot queue buffers from a request.
 515 * @uses_requests: requests are used for this queue. Set to 1 the first time
 516 *		a request is queued. Set to 0 when the queue is canceled.
 517 *		If this is 1, then you cannot queue buffers directly.
 518 * @allow_cache_hints: when set user-space can pass cache management hints in
 519 *		order to skip cache flush/invalidation on ->prepare() or/and
 520 *		->finish().
 521 * @non_coherent_mem: when set queue will attempt to allocate buffers using
 522 *		non-coherent memory.
 523 * @lock:	pointer to a mutex that protects the &struct vb2_queue. The
 524 *		driver can set this to a mutex to let the v4l2 core serialize
 525 *		the queuing ioctls. If the driver wants to handle locking
 526 *		itself, then this should be set to NULL. This lock is not used
 527 *		by the videobuf2 core API.
 528 * @owner:	The filehandle that 'owns' the buffers, i.e. the filehandle
 529 *		that called reqbufs, create_buffers or started fileio.
 530 *		This field is not used by the videobuf2 core API, but it allows
 531 *		drivers to easily associate an owner filehandle with the queue.
 532 * @ops:	driver-specific callbacks
 533 * @mem_ops:	memory allocator specific callbacks
 534 * @buf_ops:	callbacks to deliver buffer information.
 535 *		between user-space and kernel-space.
 536 * @drv_priv:	driver private data.
 537 * @subsystem_flags: Flags specific to the subsystem (V4L2/DVB/etc.). Not used
 538 *		by the vb2 core.
 539 * @buf_struct_size: size of the driver-specific buffer structure;
 540 *		"0" indicates the driver doesn't want to use a custom buffer
 541 *		structure type. In that case a subsystem-specific struct
 542 *		will be used (in the case of V4L2 that is
 543 *		``sizeof(struct vb2_v4l2_buffer)``). The first field of the
 544 *		driver-specific buffer structure must be the subsystem-specific
 545 *		struct (vb2_v4l2_buffer in the case of V4L2).
 546 * @timestamp_flags: Timestamp flags; ``V4L2_BUF_FLAG_TIMESTAMP_*`` and
 547 *		``V4L2_BUF_FLAG_TSTAMP_SRC_*``
 548 * @gfp_flags:	additional gfp flags used when allocating the buffers.
 549 *		Typically this is 0, but it may be e.g. %GFP_DMA or %__GFP_DMA32
 550 *		to force the buffer allocation to a specific memory zone.
 551 * @min_queued_buffers: the minimum number of queued buffers needed before
 552 *		@start_streaming can be called. Used when a DMA engine
 553 *		cannot be started unless at least this number of buffers
 554 *		have been queued into the driver.
 555 *		VIDIOC_REQBUFS will ensure at least @min_queued_buffers + 1
 556 *		buffers will be allocated. Note that VIDIOC_CREATE_BUFS will not
 557 *		modify the requested buffer count.
 558 * @min_reqbufs_allocation: the minimum number of buffers to be allocated when
 559 *		calling VIDIOC_REQBUFS. Note that VIDIOC_CREATE_BUFS will *not*
 560 *		modify the requested buffer count and does not use this field.
 561 *		Drivers can set this if there has to be a certain number of
 562 *		buffers available for the hardware to work effectively.
 563 *		This allows calling VIDIOC_REQBUFS with a buffer count of 1 and
 564 *		it will be automatically adjusted to a workable	buffer count.
 565 *		If set, then @min_reqbufs_allocation must be larger than
 566 *		@min_queued_buffers + 1.
 567 *		If this field is > 3, then it is highly recommended that the
 568 *		driver implements the V4L2_CID_MIN_BUFFERS_FOR_CAPTURE/OUTPUT
 569 *		control.
 570 * @alloc_devs:	&struct device memory type/allocator-specific per-plane device
 571 */
 572/*
 573 * Private elements (won't appear at the uAPI book):
 574 * @mmap_lock:	private mutex used when buffers are allocated/freed/mmapped
 575 * @memory:	current memory type used
 576 * @dma_dir:	DMA mapping direction.
 577 * @bufs:	videobuf2 buffer structures. If it is non-NULL then
 578 *		bufs_bitmap is also non-NULL.
 579 * @bufs_bitmap: bitmap tracking whether each bufs[] entry is used
 580 * @max_num_buffers: upper limit of number of allocated/used buffers.
 581 *		     If set to 0 v4l2 core will change it VB2_MAX_FRAME
 582 *		     for backward compatibility.
 583 * @queued_list: list of buffers currently queued from userspace
 584 * @queued_count: number of buffers queued and ready for streaming.
 585 * @owned_by_drv_count: number of buffers owned by the driver
 586 * @done_list:	list of buffers ready to be dequeued to userspace
 587 * @done_lock:	lock to protect done_list list
 588 * @done_wq:	waitqueue for processes waiting for buffers ready to be dequeued
 
 589 * @streaming:	current streaming state
 590 * @start_streaming_called: @start_streaming was called successfully and we
 591 *		started streaming.
 592 * @error:	a fatal error occurred on the queue
 593 * @waiting_for_buffers: used in poll() to check if vb2 is still waiting for
 594 *		buffers. Only set for capture queues if qbuf has not yet been
 595 *		called since poll() needs to return %EPOLLERR in that situation.
 596 * @waiting_in_dqbuf: set by the core for the duration of a blocking DQBUF, when
 597 *		it has to wait for a buffer to become available with vb2_queue->lock
 598 *		released. Used to prevent destroying the queue by other threads.
 599 * @is_multiplanar: set if buffer type is multiplanar
 600 * @is_output:	set if buffer type is output
 601 * @is_busy:	set if at least one buffer has been allocated at some time.
 602 * @copy_timestamp: set if vb2-core should set timestamps
 603 * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
 604 *		last decoded buffer was already dequeued. Set for capture queues
 605 *		when a buffer with the %V4L2_BUF_FLAG_LAST is dequeued.
 606 * @fileio:	file io emulator internal data, used only if emulator is active
 607 * @threadio:	thread io internal data, used only if thread is active
 608 * @name:	queue name, used for logging purpose. Initialized automatically
 609 *		if left empty by drivers.
 610 */
 611struct vb2_queue {
 612	unsigned int			type;
 613	unsigned int			io_modes;
 614	struct device			*dev;
 615	unsigned long			dma_attrs;
 616	unsigned int			bidirectional:1;
 617	unsigned int			fileio_read_once:1;
 618	unsigned int			fileio_write_immediately:1;
 619	unsigned int			allow_zero_bytesused:1;
 620	unsigned int		   quirk_poll_must_check_waiting_for_buffers:1;
 621	unsigned int			supports_requests:1;
 622	unsigned int			requires_requests:1;
 623	unsigned int			uses_qbuf:1;
 624	unsigned int			uses_requests:1;
 625	unsigned int			allow_cache_hints:1;
 626	unsigned int			non_coherent_mem:1;
 627
 628	struct mutex			*lock;
 629	void				*owner;
 630
 631	const struct vb2_ops		*ops;
 632	const struct vb2_mem_ops	*mem_ops;
 633	const struct vb2_buf_ops	*buf_ops;
 634
 635	void				*drv_priv;
 636	u32				subsystem_flags;
 637	unsigned int			buf_struct_size;
 638	u32				timestamp_flags;
 639	gfp_t				gfp_flags;
 640	u32				min_queued_buffers;
 641	u32				min_reqbufs_allocation;
 642
 643	struct device			*alloc_devs[VB2_MAX_PLANES];
 644
 645	/* private: internal use only */
 646	struct mutex			mmap_lock;
 647	unsigned int			memory;
 648	enum dma_data_direction		dma_dir;
 649	struct vb2_buffer		**bufs;
 650	unsigned long			*bufs_bitmap;
 651	unsigned int			max_num_buffers;
 652
 653	struct list_head		queued_list;
 654	unsigned int			queued_count;
 655
 656	atomic_t			owned_by_drv_count;
 657	struct list_head		done_list;
 658	spinlock_t			done_lock;
 659	wait_queue_head_t		done_wq;
 660
 
 
 661	unsigned int			streaming:1;
 662	unsigned int			start_streaming_called:1;
 663	unsigned int			error:1;
 664	unsigned int			waiting_for_buffers:1;
 665	unsigned int			waiting_in_dqbuf:1;
 666	unsigned int			is_multiplanar:1;
 667	unsigned int			is_output:1;
 668	unsigned int			is_busy:1;
 669	unsigned int			copy_timestamp:1;
 670	unsigned int			last_buffer_dequeued:1;
 671
 672	struct vb2_fileio_data		*fileio;
 673	struct vb2_threadio_data	*threadio;
 674
 675	char				name[32];
 676
 677#ifdef CONFIG_VIDEO_ADV_DEBUG
 678	/*
 679	 * Counters for how often these queue-related ops are
 680	 * called. Used to check for unbalanced ops.
 681	 */
 682	u32				cnt_queue_setup;
 683	u32				cnt_wait_prepare;
 684	u32				cnt_wait_finish;
 685	u32				cnt_prepare_streaming;
 686	u32				cnt_start_streaming;
 687	u32				cnt_stop_streaming;
 688	u32				cnt_unprepare_streaming;
 689#endif
 690};
 691
 692/**
 693 * vb2_queue_allows_cache_hints() - Return true if the queue allows cache
 694 * and memory consistency hints.
 695 *
 696 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 697 */
 698static inline bool vb2_queue_allows_cache_hints(struct vb2_queue *q)
 699{
 700	return q->allow_cache_hints && q->memory == VB2_MEMORY_MMAP;
 701}
 702
 703/**
 704 * vb2_plane_vaddr() - Return a kernel virtual address of a given plane.
 705 * @vb:		pointer to &struct vb2_buffer to which the plane in
 706 *		question belongs to.
 707 * @plane_no:	plane number for which the address is to be returned.
 708 *
 709 * This function returns a kernel virtual address of a given plane if
 710 * such a mapping exist, NULL otherwise.
 711 */
 712void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
 713
 714/**
 715 * vb2_plane_cookie() - Return allocator specific cookie for the given plane.
 716 * @vb:		pointer to &struct vb2_buffer to which the plane in
 717 *		question belongs to.
 718 * @plane_no:	plane number for which the cookie is to be returned.
 719 *
 720 * This function returns an allocator specific cookie for a given plane if
 721 * available, NULL otherwise. The allocator should provide some simple static
 722 * inline function, which would convert this cookie to the allocator specific
 723 * type that can be used directly by the driver to access the buffer. This can
 724 * be for example physical address, pointer to scatter list or IOMMU mapping.
 725 */
 726void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
 727
 728/**
 729 * vb2_buffer_done() - inform videobuf2 that an operation on a buffer
 730 *	is finished.
 731 * @vb:		pointer to &struct vb2_buffer to be used.
 732 * @state:	state of the buffer, as defined by &enum vb2_buffer_state.
 733 *		Either %VB2_BUF_STATE_DONE if the operation finished
 734 *		successfully, %VB2_BUF_STATE_ERROR if the operation finished
 735 *		with an error or %VB2_BUF_STATE_QUEUED.
 736 *
 737 * This function should be called by the driver after a hardware operation on
 738 * a buffer is finished and the buffer may be returned to userspace. The driver
 739 * cannot use this buffer anymore until it is queued back to it by videobuf
 740 * by the means of &vb2_ops->buf_queue callback. Only buffers previously queued
 741 * to the driver by &vb2_ops->buf_queue can be passed to this function.
 742 *
 743 * While streaming a buffer can only be returned in state DONE or ERROR.
 744 * The &vb2_ops->start_streaming op can also return them in case the DMA engine
 745 * cannot be started for some reason. In that case the buffers should be
 746 * returned with state QUEUED to put them back into the queue.
 747 */
 748void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
 749
 750/**
 751 * vb2_discard_done() - discard all buffers marked as DONE.
 752 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 753 *
 754 * This function is intended to be used with suspend/resume operations. It
 755 * discards all 'done' buffers as they would be too old to be requested after
 756 * resume.
 757 *
 758 * Drivers must stop the hardware and synchronize with interrupt handlers and/or
 759 * delayed works before calling this function to make sure no buffer will be
 760 * touched by the driver and/or hardware.
 761 */
 762void vb2_discard_done(struct vb2_queue *q);
 763
 764/**
 765 * vb2_wait_for_all_buffers() - wait until all buffers are given back to vb2.
 766 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 767 *
 768 * This function will wait until all buffers that have been given to the driver
 769 * by &vb2_ops->buf_queue are given back to vb2 with vb2_buffer_done(). It
 770 * doesn't call &vb2_ops->wait_prepare/&vb2_ops->wait_finish pair.
 771 * It is intended to be called with all locks taken, for example from
 772 * &vb2_ops->stop_streaming callback.
 773 */
 774int vb2_wait_for_all_buffers(struct vb2_queue *q);
 775
 776/**
 777 * vb2_core_querybuf() - query video buffer information.
 778 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 779 * @vb:		pointer to struct &vb2_buffer.
 780 * @pb:		buffer struct passed from userspace.
 781 *
 782 * Videobuf2 core helper to implement VIDIOC_QUERYBUF() operation. It is called
 783 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 784 *
 785 * The passed buffer should have been verified.
 786 *
 787 * This function fills the relevant information for the userspace.
 788 *
 789 * Return: returns zero on success; an error code otherwise.
 790 */
 791void vb2_core_querybuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);
 792
 793/**
 794 * vb2_core_reqbufs() - Initiate streaming.
 795 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 796 * @memory:	memory type, as defined by &enum vb2_memory.
 797 * @flags:	auxiliary queue/buffer management flags. Currently, the only
 798 *		used flag is %V4L2_MEMORY_FLAG_NON_COHERENT.
 799 * @count:	requested buffer count.
 800 *
 801 * Videobuf2 core helper to implement VIDIOC_REQBUF() operation. It is called
 802 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 803 *
 804 * This function:
 805 *
 806 * #) verifies streaming parameters passed from the userspace;
 807 * #) sets up the queue;
 808 * #) negotiates number of buffers and planes per buffer with the driver
 809 *    to be used during streaming;
 810 * #) allocates internal buffer structures (&struct vb2_buffer), according to
 811 *    the agreed parameters;
 812 * #) for MMAP memory type, allocates actual video memory, using the
 813 *    memory handling/allocation routines provided during queue initialization.
 814 *
 815 * If req->count is 0, all the memory will be freed instead.
 816 *
 817 * If the queue has been allocated previously by a previous vb2_core_reqbufs()
 818 * call and the queue is not busy, memory will be reallocated.
 819 *
 820 * Return: returns zero on success; an error code otherwise.
 821 */
 822int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 823		     unsigned int flags, unsigned int *count);
 824
 825/**
 826 * vb2_core_create_bufs() - Allocate buffers and any required auxiliary structs
 827 * @q: pointer to &struct vb2_queue with videobuf2 queue.
 828 * @memory: memory type, as defined by &enum vb2_memory.
 829 * @flags: auxiliary queue/buffer management flags.
 830 * @count: requested buffer count.
 831 * @requested_planes: number of planes requested.
 832 * @requested_sizes: array with the size of the planes.
 833 * @first_index: index of the first created buffer, all allocated buffers have
 834 *		 indices in the range [first_index..first_index+count-1]
 835 *
 836 * Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is
 837 * called internally by VB2 by an API-specific handler, like
 838 * ``videobuf2-v4l2.h``.
 839 *
 840 * This function:
 841 *
 842 * #) verifies parameter sanity;
 843 * #) calls the &vb2_ops->queue_setup queue operation;
 844 * #) performs any necessary memory allocations.
 845 *
 846 * Return: returns zero on success; an error code otherwise.
 847 */
 848int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 849			 unsigned int flags, unsigned int *count,
 850			 unsigned int requested_planes,
 851			 const unsigned int requested_sizes[],
 852			 unsigned int *first_index);
 853
 854/**
 855 * vb2_core_prepare_buf() - Pass ownership of a buffer from userspace
 856 *			to the kernel.
 857 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 858 * @vb:		pointer to struct &vb2_buffer.
 859 * @pb:		buffer structure passed from userspace to
 860 *		&v4l2_ioctl_ops->vidioc_prepare_buf handler in driver.
 861 *
 862 * Videobuf2 core helper to implement VIDIOC_PREPARE_BUF() operation. It is
 863 * called internally by VB2 by an API-specific handler, like
 864 * ``videobuf2-v4l2.h``.
 865 *
 866 * The passed buffer should have been verified.
 867 *
 868 * This function calls vb2_ops->buf_prepare callback in the driver
 869 * (if provided), in which driver-specific buffer initialization can
 870 * be performed.
 871 *
 872 * Return: returns zero on success; an error code otherwise.
 873 */
 874int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);
 875
 876/**
 877 * vb2_core_remove_bufs() -
 878 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 879 * @start:	first index of the range of buffers to remove.
 880 * @count:	number of buffers to remove.
 881 *
 882 *  Return: returns zero on success; an error code otherwise.
 883 */
 884int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count);
 885
 886/**
 887 * vb2_core_qbuf() - Queue a buffer from userspace
 888 *
 889 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 890 * @vb:		pointer to struct &vb2_buffer.
 891 * @pb:		buffer structure passed from userspace to
 892 *		v4l2_ioctl_ops->vidioc_qbuf handler in driver
 893 * @req:	pointer to &struct media_request, may be NULL.
 894 *
 895 * Videobuf2 core helper to implement VIDIOC_QBUF() operation. It is called
 896 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 897 *
 898 * This function:
 899 *
 900 * #) If @req is non-NULL, then the buffer will be bound to this
 901 *    media request and it returns. The buffer will be prepared and
 902 *    queued to the driver (i.e. the next two steps) when the request
 903 *    itself is queued.
 904 * #) if necessary, calls &vb2_ops->buf_prepare callback in the driver
 905 *    (if provided), in which driver-specific buffer initialization can
 906 *    be performed;
 907 * #) if streaming is on, queues the buffer in driver by the means of
 908 *    &vb2_ops->buf_queue callback for processing.
 909 *
 910 * Return: returns zero on success; an error code otherwise.
 911 */
 912int vb2_core_qbuf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb,
 913		  struct media_request *req);
 914
 915/**
 916 * vb2_core_dqbuf() - Dequeue a buffer to the userspace
 917 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 918 * @pindex:	pointer to the buffer index. May be NULL
 919 * @pb:		buffer structure passed from userspace to
 920 *		v4l2_ioctl_ops->vidioc_dqbuf handler in driver.
 921 * @nonblocking: if true, this call will not sleep waiting for a buffer if no
 922 *		 buffers ready for dequeuing are present. Normally the driver
 923 *		 would be passing (file->f_flags & O_NONBLOCK) here.
 924 *
 925 * Videobuf2 core helper to implement VIDIOC_DQBUF() operation. It is called
 926 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 927 *
 928 * This function:
 929 *
 930 * #) calls buf_finish callback in the driver (if provided), in which
 931 *    driver can perform any additional operations that may be required before
 932 *    returning the buffer to userspace, such as cache sync,
 933 * #) the buffer struct members are filled with relevant information for
 934 *    the userspace.
 935 *
 936 * Return: returns zero on success; an error code otherwise.
 937 */
 938int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb,
 939		   bool nonblocking);
 940
 941/**
 942 * vb2_core_streamon() - Implements VB2 stream ON logic
 943 *
 944 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 945 * @type:	type of the queue to be started.
 946 *		For V4L2, this is defined by &enum v4l2_buf_type type.
 947 *
 948 * Videobuf2 core helper to implement VIDIOC_STREAMON() operation. It is called
 949 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 950 *
 951 * Return: returns zero on success; an error code otherwise.
 952 */
 953int vb2_core_streamon(struct vb2_queue *q, unsigned int type);
 954
 955/**
 956 * vb2_core_streamoff() - Implements VB2 stream OFF logic
 957 *
 958 * @q:		pointer to &struct vb2_queue with videobuf2 queue
 959 * @type:	type of the queue to be started.
 960 *		For V4L2, this is defined by &enum v4l2_buf_type type.
 961 *
 962 * Videobuf2 core helper to implement VIDIOC_STREAMOFF() operation. It is
 963 * called internally by VB2 by an API-specific handler, like
 964 * ``videobuf2-v4l2.h``.
 965 *
 966 * Return: returns zero on success; an error code otherwise.
 967 */
 968int vb2_core_streamoff(struct vb2_queue *q, unsigned int type);
 969
 970/**
 971 * vb2_core_expbuf() - Export a buffer as a file descriptor.
 972 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 973 * @fd:		pointer to the file descriptor associated with DMABUF
 974 *		(set by driver).
 975 * @type:	buffer type.
 976 * @vb:		pointer to struct &vb2_buffer.
 977 * @plane:	index of the plane to be exported, 0 for single plane queues
 978 * @flags:	file flags for newly created file, as defined at
 979 *		include/uapi/asm-generic/fcntl.h.
 980 *		Currently, the only used flag is %O_CLOEXEC.
 981 *		is supported, refer to manual of open syscall for more details.
 982 *
 983 *
 984 * Videobuf2 core helper to implement VIDIOC_EXPBUF() operation. It is called
 985 * internally by VB2 by an API-specific handler, like ``videobuf2-v4l2.h``.
 986 *
 987 * Return: returns zero on success; an error code otherwise.
 988 */
 989int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
 990		    struct vb2_buffer *vb, unsigned int plane, unsigned int flags);
 991
 992/**
 993 * vb2_core_queue_init() - initialize a videobuf2 queue
 994 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
 995 *		This structure should be allocated in driver
 996 *
 997 * The &vb2_queue structure should be allocated by the driver. The driver is
 998 * responsible of clearing it's content and setting initial values for some
 999 * required entries before calling this function.
1000 *
1001 * .. note::
1002 *
1003 *    The following fields at @q should be set before calling this function:
1004 *    &vb2_queue->ops, &vb2_queue->mem_ops, &vb2_queue->type.
1005 */
1006int vb2_core_queue_init(struct vb2_queue *q);
1007
1008/**
1009 * vb2_core_queue_release() - stop streaming, release the queue and free memory
1010 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1011 *
1012 * This function stops streaming and performs necessary clean ups, including
1013 * freeing video buffer memory. The driver is responsible for freeing
1014 * the &struct vb2_queue itself.
1015 */
1016void vb2_core_queue_release(struct vb2_queue *q);
1017
1018/**
1019 * vb2_queue_error() - signal a fatal error on the queue
1020 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1021 *
1022 * Flag that a fatal unrecoverable error has occurred and wake up all processes
1023 * waiting on the queue. Polling will now set %EPOLLERR and queuing and dequeuing
1024 * buffers will return %-EIO.
1025 *
1026 * The error flag will be cleared when canceling the queue, either from
1027 * vb2_streamoff() or vb2_queue_release(). Drivers should thus not call this
1028 * function before starting the stream, otherwise the error flag will remain set
1029 * until the queue is released when closing the device node.
1030 */
1031void vb2_queue_error(struct vb2_queue *q);
1032
1033/**
1034 * vb2_mmap() - map video buffers into application address space.
1035 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1036 * @vma:	pointer to &struct vm_area_struct with the vma passed
1037 *		to the mmap file operation handler in the driver.
1038 *
1039 * Should be called from mmap file operation handler of a driver.
1040 * This function maps one plane of one of the available video buffers to
1041 * userspace. To map whole video memory allocated on reqbufs, this function
1042 * has to be called once per each plane per each buffer previously allocated.
1043 *
1044 * When the userspace application calls mmap, it passes to it an offset returned
1045 * to it earlier by the means of &v4l2_ioctl_ops->vidioc_querybuf handler.
1046 * That offset acts as a "cookie", which is then used to identify the plane
1047 * to be mapped.
1048 *
1049 * This function finds a plane with a matching offset and a mapping is performed
1050 * by the means of a provided memory operation.
1051 *
1052 * The return values from this function are intended to be directly returned
1053 * from the mmap handler in driver.
1054 */
1055int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
1056
1057#ifndef CONFIG_MMU
1058/**
1059 * vb2_get_unmapped_area - map video buffers into application address space.
1060 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1061 * @addr:	memory address.
1062 * @len:	buffer size.
1063 * @pgoff:	page offset.
1064 * @flags:	memory flags.
1065 *
1066 * This function is used in noMMU platforms to propose address mapping
1067 * for a given buffer. It's intended to be used as a handler for the
1068 * &file_operations->get_unmapped_area operation.
1069 *
1070 * This is called by the mmap() syscall routines will call this
1071 * to get a proposed address for the mapping, when ``!CONFIG_MMU``.
1072 */
1073unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
1074				    unsigned long addr,
1075				    unsigned long len,
1076				    unsigned long pgoff,
1077				    unsigned long flags);
1078#endif
1079
1080/**
1081 * vb2_core_poll() - implements poll syscall() logic.
1082 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1083 * @file:	&struct file argument passed to the poll
1084 *		file operation handler.
1085 * @wait:	&poll_table wait argument passed to the poll
1086 *		file operation handler.
1087 *
1088 * This function implements poll file operation handler for a driver.
1089 * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
1090 * be informed that the file descriptor of a video device is available for
1091 * reading.
1092 * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
1093 * will be reported as available for writing.
1094 *
1095 * The return values from this function are intended to be directly returned
1096 * from poll handler in driver.
1097 */
1098__poll_t vb2_core_poll(struct vb2_queue *q, struct file *file,
1099			   poll_table *wait);
1100
1101/**
1102 * vb2_read() - implements read() syscall logic.
1103 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1104 * @data:	pointed to target userspace buffer
1105 * @count:	number of bytes to read
1106 * @ppos:	file handle position tracking pointer
1107 * @nonblock:	mode selector (1 means blocking calls, 0 means nonblocking)
1108 */
1109size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
1110		loff_t *ppos, int nonblock);
1111/**
1112 * vb2_write() - implements write() syscall logic.
1113 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1114 * @data:	pointed to target userspace buffer
1115 * @count:	number of bytes to write
1116 * @ppos:	file handle position tracking pointer
1117 * @nonblock:	mode selector (1 means blocking calls, 0 means nonblocking)
1118 */
1119size_t vb2_write(struct vb2_queue *q, const char __user *data, size_t count,
1120		loff_t *ppos, int nonblock);
1121
1122/**
1123 * typedef vb2_thread_fnc - callback function for use with vb2_thread.
1124 *
1125 * @vb: pointer to struct &vb2_buffer.
1126 * @priv: pointer to a private data.
1127 *
1128 * This is called whenever a buffer is dequeued in the thread.
1129 */
1130typedef int (*vb2_thread_fnc)(struct vb2_buffer *vb, void *priv);
1131
1132/**
1133 * vb2_thread_start() - start a thread for the given queue.
1134 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1135 * @fnc:	&vb2_thread_fnc callback function.
1136 * @priv:	priv pointer passed to the callback function.
1137 * @thread_name:the name of the thread. This will be prefixed with "vb2-".
1138 *
1139 * This starts a thread that will queue and dequeue until an error occurs
1140 * or vb2_thread_stop() is called.
1141 *
1142 * .. attention::
1143 *
1144 *   This function should not be used for anything else but the videobuf2-dvb
1145 *   support. If you think you have another good use-case for this, then please
1146 *   contact the linux-media mailing list first.
1147 */
1148int vb2_thread_start(struct vb2_queue *q, vb2_thread_fnc fnc, void *priv,
1149		     const char *thread_name);
1150
1151/**
1152 * vb2_thread_stop() - stop the thread for the given queue.
1153 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1154 */
1155int vb2_thread_stop(struct vb2_queue *q);
1156
1157/**
1158 * vb2_is_streaming() - return streaming status of the queue.
1159 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1160 */
1161static inline bool vb2_is_streaming(struct vb2_queue *q)
1162{
1163	return q->streaming;
1164}
1165
1166/**
1167 * vb2_fileio_is_active() - return true if fileio is active.
1168 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1169 *
1170 * This returns true if read() or write() is used to stream the data
1171 * as opposed to stream I/O. This is almost never an important distinction,
1172 * except in rare cases. One such case is that using read() or write() to
1173 * stream a format using %V4L2_FIELD_ALTERNATE is not allowed since there
1174 * is no way you can pass the field information of each buffer to/from
1175 * userspace. A driver that supports this field format should check for
1176 * this in the &vb2_ops->queue_setup op and reject it if this function returns
1177 * true.
1178 */
1179static inline bool vb2_fileio_is_active(struct vb2_queue *q)
1180{
1181	return q->fileio;
1182}
1183
1184/**
1185 * vb2_get_num_buffers() - get the number of buffer in a queue
1186 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1187 */
1188static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q)
1189{
1190	if (q->bufs_bitmap)
1191		return bitmap_weight(q->bufs_bitmap, q->max_num_buffers);
1192
1193	return 0;
1194}
1195
1196/**
1197 * vb2_is_busy() - return busy status of the queue.
1198 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1199 *
1200 * This function checks if queue has any buffers allocated.
1201 */
1202static inline bool vb2_is_busy(struct vb2_queue *q)
1203{
1204	return !!q->is_busy;
1205}
1206
1207/**
1208 * vb2_get_drv_priv() - return driver private data associated with the queue.
1209 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1210 */
1211static inline void *vb2_get_drv_priv(struct vb2_queue *q)
1212{
1213	return q->drv_priv;
1214}
1215
1216/**
1217 * vb2_set_plane_payload() - set bytesused for the plane @plane_no.
1218 * @vb:		pointer to &struct vb2_buffer to which the plane in
1219 *		question belongs to.
1220 * @plane_no:	plane number for which payload should be set.
1221 * @size:	payload in bytes.
1222 */
1223static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
1224				 unsigned int plane_no, unsigned long size)
1225{
1226	/*
1227	 * size must never be larger than the buffer length, so
1228	 * warn and clamp to the buffer length if that's the case.
1229	 */
1230	if (plane_no < vb->num_planes) {
1231		if (WARN_ON_ONCE(size > vb->planes[plane_no].length))
1232			size = vb->planes[plane_no].length;
1233		vb->planes[plane_no].bytesused = size;
1234	}
1235}
1236
1237/**
1238 * vb2_get_plane_payload() - get bytesused for the plane plane_no
1239 * @vb:		pointer to &struct vb2_buffer to which the plane in
1240 *		question belongs to.
1241 * @plane_no:	plane number for which payload should be set.
1242 */
1243static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
1244				 unsigned int plane_no)
1245{
1246	if (plane_no < vb->num_planes)
1247		return vb->planes[plane_no].bytesused;
1248	return 0;
1249}
1250
1251/**
1252 * vb2_plane_size() - return plane size in bytes.
1253 * @vb:		pointer to &struct vb2_buffer to which the plane in
1254 *		question belongs to.
1255 * @plane_no:	plane number for which size should be returned.
1256 */
1257static inline unsigned long
1258vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
1259{
1260	if (plane_no < vb->num_planes)
1261		return vb->planes[plane_no].length;
1262	return 0;
1263}
1264
1265/**
1266 * vb2_start_streaming_called() - return streaming status of driver.
1267 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1268 */
1269static inline bool vb2_start_streaming_called(struct vb2_queue *q)
1270{
1271	return q->start_streaming_called;
1272}
1273
1274/**
1275 * vb2_clear_last_buffer_dequeued() - clear last buffer dequeued flag of queue.
1276 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1277 */
1278static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)
1279{
1280	q->last_buffer_dequeued = false;
1281}
1282
1283/**
1284 * vb2_get_buffer() - get a buffer from a queue
1285 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1286 * @index:	buffer index
1287 *
1288 * This function obtains a buffer from a queue, by its index.
1289 * Keep in mind that there is no refcounting involved in this
1290 * operation, so the buffer lifetime should be taken into
1291 * consideration.
1292 */
1293static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
1294						unsigned int index)
1295{
1296	if (!q->bufs)
1297		return NULL;
1298
1299	if (index >= q->max_num_buffers)
1300		return NULL;
1301
1302	if (test_bit(index, q->bufs_bitmap))
1303		return q->bufs[index];
1304	return NULL;
1305}
1306
1307/*
1308 * The following functions are not part of the vb2 core API, but are useful
1309 * functions for videobuf2-*.
1310 */
1311
1312/**
1313 * vb2_buffer_in_use() - return true if the buffer is in use and
1314 * the queue cannot be freed (by the means of VIDIOC_REQBUFS(0)) call.
1315 *
1316 * @vb:		buffer for which plane size should be returned.
1317 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1318 */
1319bool vb2_buffer_in_use(struct vb2_queue *q, struct vb2_buffer *vb);
1320
1321/**
1322 * vb2_verify_memory_type() - Check whether the memory type and buffer type
1323 * passed to a buffer operation are compatible with the queue.
1324 *
1325 * @q:		pointer to &struct vb2_queue with videobuf2 queue.
1326 * @memory:	memory model, as defined by enum &vb2_memory.
1327 * @type:	private buffer type whose content is defined by the vb2-core
1328 *		caller. For example, for V4L2, it should match
1329 *		the types defined on enum &v4l2_buf_type.
1330 */
1331int vb2_verify_memory_type(struct vb2_queue *q,
1332		enum vb2_memory memory, unsigned int type);
1333
1334/**
1335 * vb2_request_object_is_buffer() - return true if the object is a buffer
1336 *
1337 * @obj:	the request object.
1338 */
1339bool vb2_request_object_is_buffer(struct media_request_object *obj);
1340
1341/**
1342 * vb2_request_buffer_cnt() - return the number of buffers in the request
1343 *
1344 * @req:	the request.
1345 */
1346unsigned int vb2_request_buffer_cnt(struct media_request *req);
1347
1348#endif /* _MEDIA_VIDEOBUF2_CORE_H */