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Linux/include/media/videobuf2-v4l2.h

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  1 /*
  2  * videobuf2-v4l2.h - V4L2 driver helper 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_V4L2_H
 13 #define _MEDIA_VIDEOBUF2_V4L2_H
 14 
 15 #include <linux/videodev2.h>
 16 #include <media/videobuf2-core.h>
 17 
 18 #if VB2_MAX_FRAME != VIDEO_MAX_FRAME
 19 #error VB2_MAX_FRAME != VIDEO_MAX_FRAME
 20 #endif
 21 
 22 #if VB2_MAX_PLANES != VIDEO_MAX_PLANES
 23 #error VB2_MAX_PLANES != VIDEO_MAX_PLANES
 24 #endif
 25 
 26 /**
 27  * struct vb2_v4l2_buffer - video buffer information for v4l2.
 28  *
 29  * @vb2_buf:    embedded struct &vb2_buffer.
 30  * @flags:      buffer informational flags.
 31  * @field:      field order of the image in the buffer, as defined by
 32  *              &enum v4l2_field.
 33  * @timecode:   frame timecode.
 34  * @sequence:   sequence count of this frame.
 35  *
 36  * Should contain enough information to be able to cover all the fields
 37  * of &struct v4l2_buffer at ``videodev2.h``.
 38  */
 39 struct vb2_v4l2_buffer {
 40         struct vb2_buffer       vb2_buf;
 41 
 42         __u32                   flags;
 43         __u32                   field;
 44         struct v4l2_timecode    timecode;
 45         __u32                   sequence;
 46 };
 47 
 48 /*
 49  * to_vb2_v4l2_buffer() - cast struct vb2_buffer * to struct vb2_v4l2_buffer *
 50  */
 51 #define to_vb2_v4l2_buffer(vb) \
 52         container_of(vb, struct vb2_v4l2_buffer, vb2_buf)
 53 
 54 int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
 55 
 56 /**
 57  * vb2_reqbufs() - Wrapper for vb2_core_reqbufs() that also verifies
 58  * the memory and type values.
 59  *
 60  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
 61  * @req:        &struct v4l2_requestbuffers passed from userspace to
 62  *              &v4l2_ioctl_ops->vidioc_reqbufs handler in driver.
 63  */
 64 int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
 65 
 66 /**
 67  * vb2_create_bufs() - Wrapper for vb2_core_create_bufs() that also verifies
 68  * the memory and type values.
 69  *
 70  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
 71  * @create:     creation parameters, passed from userspace to
 72  *              &v4l2_ioctl_ops->vidioc_create_bufs handler in driver
 73  */
 74 int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
 75 
 76 /**
 77  * vb2_prepare_buf() - Pass ownership of a buffer from userspace to the kernel
 78  *
 79  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
 80  * @b:          buffer structure passed from userspace to
 81  *              &v4l2_ioctl_ops->vidioc_prepare_buf handler in driver
 82  *
 83  * Should be called from &v4l2_ioctl_ops->vidioc_prepare_buf ioctl handler
 84  * of a driver.
 85  *
 86  * This function:
 87  *
 88  * #) verifies the passed buffer,
 89  * #) calls &vb2_ops->buf_prepare callback in the driver (if provided),
 90  *    in which driver-specific buffer initialization can be performed.
 91  *
 92  * The return values from this function are intended to be directly returned
 93  * from &v4l2_ioctl_ops->vidioc_prepare_buf handler in driver.
 94  */
 95 int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b);
 96 
 97 /**
 98  * vb2_qbuf() - Queue a buffer from userspace
 99  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
100  * @b:          buffer structure passed from userspace to
101  *              &v4l2_ioctl_ops->vidioc_qbuf handler in driver
102  *
103  * Should be called from &v4l2_ioctl_ops->vidioc_qbuf handler of a driver.
104  *
105  * This function:
106  *
107  * #) verifies the passed buffer;
108  * #) if necessary, calls &vb2_ops->buf_prepare callback in the driver
109  *    (if provided), in which driver-specific buffer initialization can
110  *    be performed;
111  * #) if streaming is on, queues the buffer in driver by the means of
112  *    &vb2_ops->buf_queue callback for processing.
113  *
114  * The return values from this function are intended to be directly returned
115  * from &v4l2_ioctl_ops->vidioc_qbuf handler in driver.
116  */
117 int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
118 
119 /**
120  * vb2_expbuf() - Export a buffer as a file descriptor
121  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
122  * @eb:         export buffer structure passed from userspace to
123  *              &v4l2_ioctl_ops->vidioc_expbuf handler in driver
124  *
125  * The return values from this function are intended to be directly returned
126  * from &v4l2_ioctl_ops->vidioc_expbuf handler in driver.
127  */
128 int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb);
129 
130 /**
131  * vb2_dqbuf() - Dequeue a buffer to the userspace
132  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
133  * @b:          buffer structure passed from userspace to
134  *              &v4l2_ioctl_ops->vidioc_dqbuf handler in driver
135  * @nonblocking: if true, this call will not sleep waiting for a buffer if no
136  *               buffers ready for dequeuing are present. Normally the driver
137  *               would be passing (&file->f_flags & %O_NONBLOCK) here
138  *
139  * Should be called from &v4l2_ioctl_ops->vidioc_dqbuf ioctl handler
140  * of a driver.
141  *
142  * This function:
143  *
144  * #) verifies the passed buffer;
145  * #) calls &vb2_ops->buf_finish callback in the driver (if provided), in which
146  *    driver can perform any additional operations that may be required before
147  *    returning the buffer to userspace, such as cache sync;
148  * #) the buffer struct members are filled with relevant information for
149  *    the userspace.
150  *
151  * The return values from this function are intended to be directly returned
152  * from &v4l2_ioctl_ops->vidioc_dqbuf handler in driver.
153  */
154 int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
155 
156 /**
157  * vb2_streamon - start streaming
158  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
159  * @type:       type argument passed from userspace to vidioc_streamon handler,
160  *              as defined by &enum v4l2_buf_type.
161  *
162  * Should be called from &v4l2_ioctl_ops->vidioc_streamon handler of a driver.
163  *
164  * This function:
165  *
166  * 1) verifies current state
167  * 2) passes any previously queued buffers to the driver and starts streaming
168  *
169  * The return values from this function are intended to be directly returned
170  * from &v4l2_ioctl_ops->vidioc_streamon handler in the driver.
171  */
172 int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
173 
174 /**
175  * vb2_streamoff - stop streaming
176  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
177  * @type:       type argument passed from userspace to vidioc_streamoff handler
178  *
179  * Should be called from vidioc_streamoff handler of a driver.
180  *
181  * This function:
182  *
183  * #) verifies current state,
184  * #) stop streaming and dequeues any queued buffers, including those previously
185  *    passed to the driver (after waiting for the driver to finish).
186  *
187  * This call can be used for pausing playback.
188  * The return values from this function are intended to be directly returned
189  * from vidioc_streamoff handler in the driver
190  */
191 int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
192 
193 /**
194  * vb2_queue_init() - initialize a videobuf2 queue
195  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
196  *
197  * The vb2_queue structure should be allocated by the driver. The driver is
198  * responsible of clearing it's content and setting initial values for some
199  * required entries before calling this function.
200  * q->ops, q->mem_ops, q->type and q->io_modes are mandatory. Please refer
201  * to the struct vb2_queue description in include/media/videobuf2-core.h
202  * for more information.
203  */
204 int __must_check vb2_queue_init(struct vb2_queue *q);
205 
206 /**
207  * vb2_queue_release() - stop streaming, release the queue and free memory
208  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
209  *
210  * This function stops streaming and performs necessary clean ups, including
211  * freeing video buffer memory. The driver is responsible for freeing
212  * the vb2_queue structure itself.
213  */
214 void vb2_queue_release(struct vb2_queue *q);
215 
216 /**
217  * vb2_poll() - implements poll userspace operation
218  * @q:          pointer to &struct vb2_queue with videobuf2 queue.
219  * @file:       file argument passed to the poll file operation handler
220  * @wait:       wait argument passed to the poll file operation handler
221  *
222  * This function implements poll file operation handler for a driver.
223  * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
224  * be informed that the file descriptor of a video device is available for
225  * reading.
226  * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
227  * will be reported as available for writing.
228  *
229  * If the driver uses struct v4l2_fh, then vb2_poll() will also check for any
230  * pending events.
231  *
232  * The return values from this function are intended to be directly returned
233  * from poll handler in driver.
234  */
235 __poll_t vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
236 
237 /*
238  * The following functions are not part of the vb2 core API, but are simple
239  * helper functions that you can use in your struct v4l2_file_operations,
240  * struct v4l2_ioctl_ops and struct vb2_ops. They will serialize if vb2_queue->lock
241  * or video_device->lock is set, and they will set and test vb2_queue->owner
242  * to check if the calling filehandle is permitted to do the queuing operation.
243  */
244 
245 /* struct v4l2_ioctl_ops helpers */
246 
247 int vb2_ioctl_reqbufs(struct file *file, void *priv,
248                           struct v4l2_requestbuffers *p);
249 int vb2_ioctl_create_bufs(struct file *file, void *priv,
250                           struct v4l2_create_buffers *p);
251 int vb2_ioctl_prepare_buf(struct file *file, void *priv,
252                           struct v4l2_buffer *p);
253 int vb2_ioctl_querybuf(struct file *file, void *priv, struct v4l2_buffer *p);
254 int vb2_ioctl_qbuf(struct file *file, void *priv, struct v4l2_buffer *p);
255 int vb2_ioctl_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p);
256 int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i);
257 int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i);
258 int vb2_ioctl_expbuf(struct file *file, void *priv,
259         struct v4l2_exportbuffer *p);
260 
261 /* struct v4l2_file_operations helpers */
262 
263 int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
264 int vb2_fop_release(struct file *file);
265 int _vb2_fop_release(struct file *file, struct mutex *lock);
266 ssize_t vb2_fop_write(struct file *file, const char __user *buf,
267                 size_t count, loff_t *ppos);
268 ssize_t vb2_fop_read(struct file *file, char __user *buf,
269                 size_t count, loff_t *ppos);
270 __poll_t vb2_fop_poll(struct file *file, poll_table *wait);
271 #ifndef CONFIG_MMU
272 unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr,
273                 unsigned long len, unsigned long pgoff, unsigned long flags);
274 #endif
275 
276 /**
277  * vb2_ops_wait_prepare - helper function to lock a struct &vb2_queue
278  *
279  * @vq: pointer to &struct vb2_queue
280  *
281  * ..note:: only use if vq->lock is non-NULL.
282  */
283 void vb2_ops_wait_prepare(struct vb2_queue *vq);
284 
285 /**
286  * vb2_ops_wait_finish - helper function to unlock a struct &vb2_queue
287  *
288  * @vq: pointer to &struct vb2_queue
289  *
290  * ..note:: only use if vq->lock is non-NULL.
291  */
292 void vb2_ops_wait_finish(struct vb2_queue *vq);
293 
294 #endif /* _MEDIA_VIDEOBUF2_V4L2_H */
295 

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