linux/include/media/videobuf2-core.h
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   1/*
   2 * videobuf2-core.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_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/videodev2.h>
  19
  20struct vb2_alloc_ctx;
  21struct vb2_fileio_data;
  22
  23/**
  24 * struct vb2_mem_ops - memory handling/memory allocator operations
  25 * @alloc:      allocate video memory and, optionally, allocator private data,
  26 *              return NULL on failure or a pointer to allocator private,
  27 *              per-buffer data on success; the returned private structure
  28 *              will then be passed as buf_priv argument to other ops in this
  29 *              structure
  30 * @put:        inform the allocator that the buffer will no longer be used;
  31 *              usually will result in the allocator freeing the buffer (if
  32 *              no other users of this buffer are present); the buf_priv
  33 *              argument is the allocator private per-buffer structure
  34 *              previously returned from the alloc callback
  35 * @get_userptr: acquire userspace memory for a hardware operation; used for
  36 *               USERPTR memory types; vaddr is the address passed to the
  37 *               videobuf layer when queuing a video buffer of USERPTR type;
  38 *               should return an allocator private per-buffer structure
  39 *               associated with the buffer on success, NULL on failure;
  40 *               the returned private structure will then be passed as buf_priv
  41 *               argument to other ops in this structure
  42 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
  43 *               be used
  44 * @vaddr:      return a kernel virtual address to a given memory buffer
  45 *              associated with the passed private structure or NULL if no
  46 *              such mapping exists
  47 * @cookie:     return allocator specific cookie for a given memory buffer
  48 *              associated with the passed private structure or NULL if not
  49 *              available
  50 * @num_users:  return the current number of users of a memory buffer;
  51 *              return 1 if the videobuf layer (or actually the driver using
  52 *              it) is the only user
  53 * @mmap:       setup a userspace mapping for a given memory buffer under
  54 *              the provided virtual memory region
  55 *
  56 * Required ops for USERPTR types: get_userptr, put_userptr.
  57 * Required ops for MMAP types: alloc, put, num_users, mmap.
  58 * Required ops for read/write access types: alloc, put, num_users, vaddr
  59 */
  60struct vb2_mem_ops {
  61        void            *(*alloc)(void *alloc_ctx, unsigned long size);
  62        void            (*put)(void *buf_priv);
  63
  64        void            *(*get_userptr)(void *alloc_ctx, unsigned long vaddr,
  65                                        unsigned long size, int write);
  66        void            (*put_userptr)(void *buf_priv);
  67
  68        void            *(*vaddr)(void *buf_priv);
  69        void            *(*cookie)(void *buf_priv);
  70
  71        unsigned int    (*num_users)(void *buf_priv);
  72
  73        int             (*mmap)(void *buf_priv, struct vm_area_struct *vma);
  74};
  75
  76struct vb2_plane {
  77        void                    *mem_priv;
  78};
  79
  80/**
  81 * enum vb2_io_modes - queue access methods
  82 * @VB2_MMAP:           driver supports MMAP with streaming API
  83 * @VB2_USERPTR:        driver supports USERPTR with streaming API
  84 * @VB2_READ:           driver supports read() style access
  85 * @VB2_WRITE:          driver supports write() style access
  86 */
  87enum vb2_io_modes {
  88        VB2_MMAP        = (1 << 0),
  89        VB2_USERPTR     = (1 << 1),
  90        VB2_READ        = (1 << 2),
  91        VB2_WRITE       = (1 << 3),
  92};
  93
  94/**
  95 * enum vb2_fileio_flags - flags for selecting a mode of the file io emulator,
  96 * by default the 'streaming' style is used by the file io emulator
  97 * @VB2_FILEIO_READ_ONCE:       report EOF after reading the first buffer
  98 * @VB2_FILEIO_WRITE_IMMEDIATELY:       queue buffer after each write() call
  99 */
 100enum vb2_fileio_flags {
 101        VB2_FILEIO_READ_ONCE            = (1 << 0),
 102        VB2_FILEIO_WRITE_IMMEDIATELY    = (1 << 1),
 103};
 104
 105/**
 106 * enum vb2_buffer_state - current video buffer state
 107 * @VB2_BUF_STATE_DEQUEUED:     buffer under userspace control
 108 * @VB2_BUF_STATE_PREPARED:     buffer prepared in videobuf and by the driver
 109 * @VB2_BUF_STATE_QUEUED:       buffer queued in videobuf, but not in driver
 110 * @VB2_BUF_STATE_ACTIVE:       buffer queued in driver and possibly used
 111 *                              in a hardware operation
 112 * @VB2_BUF_STATE_DONE:         buffer returned from driver to videobuf, but
 113 *                              not yet dequeued to userspace
 114 * @VB2_BUF_STATE_ERROR:        same as above, but the operation on the buffer
 115 *                              has ended with an error, which will be reported
 116 *                              to the userspace when it is dequeued
 117 */
 118enum vb2_buffer_state {
 119        VB2_BUF_STATE_DEQUEUED,
 120        VB2_BUF_STATE_PREPARED,
 121        VB2_BUF_STATE_QUEUED,
 122        VB2_BUF_STATE_ACTIVE,
 123        VB2_BUF_STATE_DONE,
 124        VB2_BUF_STATE_ERROR,
 125};
 126
 127struct vb2_queue;
 128
 129/**
 130 * struct vb2_buffer - represents a video buffer
 131 * @v4l2_buf:           struct v4l2_buffer associated with this buffer; can
 132 *                      be read by the driver and relevant entries can be
 133 *                      changed by the driver in case of CAPTURE types
 134 *                      (such as timestamp)
 135 * @v4l2_planes:        struct v4l2_planes associated with this buffer; can
 136 *                      be read by the driver and relevant entries can be
 137 *                      changed by the driver in case of CAPTURE types
 138 *                      (such as bytesused); NOTE that even for single-planar
 139 *                      types, the v4l2_planes[0] struct should be used
 140 *                      instead of v4l2_buf for filling bytesused - drivers
 141 *                      should use the vb2_set_plane_payload() function for that
 142 * @vb2_queue:          the queue to which this driver belongs
 143 * @num_planes:         number of planes in the buffer
 144 *                      on an internal driver queue
 145 * @state:              current buffer state; do not change
 146 * @queued_entry:       entry on the queued buffers list, which holds all
 147 *                      buffers queued from userspace
 148 * @done_entry:         entry on the list that stores all buffers ready to
 149 *                      be dequeued to userspace
 150 * @planes:             private per-plane information; do not change
 151 */
 152struct vb2_buffer {
 153        struct v4l2_buffer      v4l2_buf;
 154        struct v4l2_plane       v4l2_planes[VIDEO_MAX_PLANES];
 155
 156        struct vb2_queue        *vb2_queue;
 157
 158        unsigned int            num_planes;
 159
 160/* Private: internal use only */
 161        enum vb2_buffer_state   state;
 162
 163        struct list_head        queued_entry;
 164        struct list_head        done_entry;
 165
 166        struct vb2_plane        planes[VIDEO_MAX_PLANES];
 167};
 168
 169/**
 170 * struct vb2_ops - driver-specific callbacks
 171 *
 172 * @queue_setup:        called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS
 173 *                      handlers before memory allocation, or, if
 174 *                      *num_planes != 0, after the allocation to verify a
 175 *                      smaller number of buffers. Driver should return
 176 *                      the required number of buffers in *num_buffers, the
 177 *                      required number of planes per buffer in *num_planes; the
 178 *                      size of each plane should be set in the sizes[] array
 179 *                      and optional per-plane allocator specific context in the
 180 *                      alloc_ctxs[] array. When called from VIDIOC_REQBUFS,
 181 *                      fmt == NULL, the driver has to use the currently
 182 *                      configured format and *num_buffers is the total number
 183 *                      of buffers, that are being allocated. When called from
 184 *                      VIDIOC_CREATE_BUFS, fmt != NULL and it describes the
 185 *                      target frame format. In this case *num_buffers are being
 186 *                      allocated additionally to q->num_buffers.
 187 * @wait_prepare:       release any locks taken while calling vb2 functions;
 188 *                      it is called before an ioctl needs to wait for a new
 189 *                      buffer to arrive; required to avoid a deadlock in
 190 *                      blocking access type
 191 * @wait_finish:        reacquire all locks released in the previous callback;
 192 *                      required to continue operation after sleeping while
 193 *                      waiting for a new buffer to arrive
 194 * @buf_init:           called once after allocating a buffer (in MMAP case)
 195 *                      or after acquiring a new USERPTR buffer; drivers may
 196 *                      perform additional buffer-related initialization;
 197 *                      initialization failure (return != 0) will prevent
 198 *                      queue setup from completing successfully; optional
 199 * @buf_prepare:        called every time the buffer is queued from userspace
 200 *                      and from the VIDIOC_PREPARE_BUF ioctl; drivers may
 201 *                      perform any initialization required before each hardware
 202 *                      operation in this callback; if an error is returned, the
 203 *                      buffer will not be queued in driver; optional
 204 * @buf_finish:         called before every dequeue of the buffer back to
 205 *                      userspace; drivers may perform any operations required
 206 *                      before userspace accesses the buffer; optional
 207 * @buf_cleanup:        called once before the buffer is freed; drivers may
 208 *                      perform any additional cleanup; optional
 209 * @start_streaming:    called once to enter 'streaming' state; the driver may
 210 *                      receive buffers with @buf_queue callback before
 211 *                      @start_streaming is called; the driver gets the number
 212 *                      of already queued buffers in count parameter; driver
 213 *                      can return an error if hardware fails or not enough
 214 *                      buffers has been queued, in such case all buffers that
 215 *                      have been already given by the @buf_queue callback are
 216 *                      invalidated.
 217 * @stop_streaming:     called when 'streaming' state must be disabled; driver
 218 *                      should stop any DMA transactions or wait until they
 219 *                      finish and give back all buffers it got from buf_queue()
 220 *                      callback; may use vb2_wait_for_all_buffers() function
 221 * @buf_queue:          passes buffer vb to the driver; driver may start
 222 *                      hardware operation on this buffer; driver should give
 223 *                      the buffer back by calling vb2_buffer_done() function;
 224 *                      it is allways called after calling STREAMON ioctl;
 225 *                      might be called before start_streaming callback if user
 226 *                      pre-queued buffers before calling STREAMON
 227 */
 228struct vb2_ops {
 229        int (*queue_setup)(struct vb2_queue *q, const struct v4l2_format *fmt,
 230                           unsigned int *num_buffers, unsigned int *num_planes,
 231                           unsigned int sizes[], void *alloc_ctxs[]);
 232
 233        void (*wait_prepare)(struct vb2_queue *q);
 234        void (*wait_finish)(struct vb2_queue *q);
 235
 236        int (*buf_init)(struct vb2_buffer *vb);
 237        int (*buf_prepare)(struct vb2_buffer *vb);
 238        int (*buf_finish)(struct vb2_buffer *vb);
 239        void (*buf_cleanup)(struct vb2_buffer *vb);
 240
 241        int (*start_streaming)(struct vb2_queue *q, unsigned int count);
 242        int (*stop_streaming)(struct vb2_queue *q);
 243
 244        void (*buf_queue)(struct vb2_buffer *vb);
 245};
 246
 247struct v4l2_fh;
 248
 249/**
 250 * struct vb2_queue - a videobuf queue
 251 *
 252 * @type:       queue type (see V4L2_BUF_TYPE_* in linux/videodev2.h
 253 * @io_modes:   supported io methods (see vb2_io_modes enum)
 254 * @io_flags:   additional io flags (see vb2_fileio_flags enum)
 255 * @lock:       pointer to a mutex that protects the vb2_queue struct. The
 256 *              driver can set this to a mutex to let the v4l2 core serialize
 257 *              the queuing ioctls. If the driver wants to handle locking
 258 *              itself, then this should be set to NULL. This lock is not used
 259 *              by the videobuf2 core API.
 260 * @owner:      The filehandle that 'owns' the buffers, i.e. the filehandle
 261 *              that called reqbufs, create_buffers or started fileio.
 262 *              This field is not used by the videobuf2 core API, but it allows
 263 *              drivers to easily associate an owner filehandle with the queue.
 264 * @ops:        driver-specific callbacks
 265 * @mem_ops:    memory allocator specific callbacks
 266 * @drv_priv:   driver private data
 267 * @buf_struct_size: size of the driver-specific buffer structure;
 268 *              "0" indicates the driver doesn't want to use a custom buffer
 269 *              structure type, so sizeof(struct vb2_buffer) will is used
 270 *
 271 * @memory:     current memory type used
 272 * @bufs:       videobuf buffer structures
 273 * @num_buffers: number of allocated/used buffers
 274 * @queued_list: list of buffers currently queued from userspace
 275 * @queued_count: number of buffers owned by the driver
 276 * @done_list:  list of buffers ready to be dequeued to userspace
 277 * @done_lock:  lock to protect done_list list
 278 * @done_wq:    waitqueue for processes waiting for buffers ready to be dequeued
 279 * @alloc_ctx:  memory type/allocator-specific contexts for each plane
 280 * @streaming:  current streaming state
 281 * @fileio:     file io emulator internal data, used only if emulator is active
 282 */
 283struct vb2_queue {
 284        enum v4l2_buf_type              type;
 285        unsigned int                    io_modes;
 286        unsigned int                    io_flags;
 287        struct mutex                    *lock;
 288        struct v4l2_fh                  *owner;
 289
 290        const struct vb2_ops            *ops;
 291        const struct vb2_mem_ops        *mem_ops;
 292        void                            *drv_priv;
 293        unsigned int                    buf_struct_size;
 294
 295/* private: internal use only */
 296        enum v4l2_memory                memory;
 297        struct vb2_buffer               *bufs[VIDEO_MAX_FRAME];
 298        unsigned int                    num_buffers;
 299
 300        struct list_head                queued_list;
 301
 302        atomic_t                        queued_count;
 303        struct list_head                done_list;
 304        spinlock_t                      done_lock;
 305        wait_queue_head_t               done_wq;
 306
 307        void                            *alloc_ctx[VIDEO_MAX_PLANES];
 308        unsigned int                    plane_sizes[VIDEO_MAX_PLANES];
 309
 310        unsigned int                    streaming:1;
 311
 312        struct vb2_fileio_data          *fileio;
 313};
 314
 315void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
 316void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
 317
 318void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
 319int vb2_wait_for_all_buffers(struct vb2_queue *q);
 320
 321int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
 322int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
 323
 324int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
 325int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b);
 326
 327int vb2_queue_init(struct vb2_queue *q);
 328
 329void vb2_queue_release(struct vb2_queue *q);
 330
 331int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
 332int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
 333
 334int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
 335int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
 336
 337int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
 338#ifndef CONFIG_MMU
 339unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
 340                                    unsigned long addr,
 341                                    unsigned long len,
 342                                    unsigned long pgoff,
 343                                    unsigned long flags);
 344#endif
 345unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
 346size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
 347                loff_t *ppos, int nonblock);
 348size_t vb2_write(struct vb2_queue *q, char __user *data, size_t count,
 349                loff_t *ppos, int nonblock);
 350
 351/**
 352 * vb2_is_streaming() - return streaming status of the queue
 353 * @q:          videobuf queue
 354 */
 355static inline bool vb2_is_streaming(struct vb2_queue *q)
 356{
 357        return q->streaming;
 358}
 359
 360/**
 361 * vb2_is_busy() - return busy status of the queue
 362 * @q:          videobuf queue
 363 *
 364 * This function checks if queue has any buffers allocated.
 365 */
 366static inline bool vb2_is_busy(struct vb2_queue *q)
 367{
 368        return (q->num_buffers > 0);
 369}
 370
 371/**
 372 * vb2_get_drv_priv() - return driver private data associated with the queue
 373 * @q:          videobuf queue
 374 */
 375static inline void *vb2_get_drv_priv(struct vb2_queue *q)
 376{
 377        return q->drv_priv;
 378}
 379
 380/**
 381 * vb2_set_plane_payload() - set bytesused for the plane plane_no
 382 * @vb:         buffer for which plane payload should be set
 383 * @plane_no:   plane number for which payload should be set
 384 * @size:       payload in bytes
 385 */
 386static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
 387                                 unsigned int plane_no, unsigned long size)
 388{
 389        if (plane_no < vb->num_planes)
 390                vb->v4l2_planes[plane_no].bytesused = size;
 391}
 392
 393/**
 394 * vb2_get_plane_payload() - get bytesused for the plane plane_no
 395 * @vb:         buffer for which plane payload should be set
 396 * @plane_no:   plane number for which payload should be set
 397 * @size:       payload in bytes
 398 */
 399static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
 400                                 unsigned int plane_no)
 401{
 402        if (plane_no < vb->num_planes)
 403                return vb->v4l2_planes[plane_no].bytesused;
 404        return 0;
 405}
 406
 407/**
 408 * vb2_plane_size() - return plane size in bytes
 409 * @vb:         buffer for which plane size should be returned
 410 * @plane_no:   plane number for which size should be returned
 411 */
 412static inline unsigned long
 413vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
 414{
 415        if (plane_no < vb->num_planes)
 416                return vb->v4l2_planes[plane_no].length;
 417        return 0;
 418}
 419
 420/*
 421 * The following functions are not part of the vb2 core API, but are simple
 422 * helper functions that you can use in your struct v4l2_file_operations,
 423 * struct v4l2_ioctl_ops and struct vb2_ops. They will serialize if vb2_queue->lock
 424 * or video_device->lock is set, and they will set and test vb2_queue->owner
 425 * to check if the calling filehandle is permitted to do the queuing operation.
 426 */
 427
 428/* struct v4l2_ioctl_ops helpers */
 429
 430int vb2_ioctl_reqbufs(struct file *file, void *priv,
 431                          struct v4l2_requestbuffers *p);
 432int vb2_ioctl_create_bufs(struct file *file, void *priv,
 433                          struct v4l2_create_buffers *p);
 434int vb2_ioctl_prepare_buf(struct file *file, void *priv,
 435                          struct v4l2_buffer *p);
 436int vb2_ioctl_querybuf(struct file *file, void *priv, struct v4l2_buffer *p);
 437int vb2_ioctl_qbuf(struct file *file, void *priv, struct v4l2_buffer *p);
 438int vb2_ioctl_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p);
 439int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i);
 440int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i);
 441
 442/* struct v4l2_file_operations helpers */
 443
 444int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
 445int vb2_fop_release(struct file *file);
 446ssize_t vb2_fop_write(struct file *file, char __user *buf,
 447                size_t count, loff_t *ppos);
 448ssize_t vb2_fop_read(struct file *file, char __user *buf,
 449                size_t count, loff_t *ppos);
 450unsigned int vb2_fop_poll(struct file *file, poll_table *wait);
 451#ifndef CONFIG_MMU
 452unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr,
 453                unsigned long len, unsigned long pgoff, unsigned long flags);
 454#endif
 455
 456/* struct vb2_ops helpers, only use if vq->lock is non-NULL. */
 457
 458void vb2_ops_wait_prepare(struct vb2_queue *vq);
 459void vb2_ops_wait_finish(struct vb2_queue *vq);
 460
 461#endif /* _MEDIA_VIDEOBUF2_CORE_H */
 462
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