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