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TOMOYO Linux Cross Reference
Linux/include/media/videobuf2-core.h

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

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