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#include <linux/dma-buf.h>
  20
  21struct vb2_alloc_ctx;
  22struct vb2_fileio_data;
  23
  24/**
  25 * struct vb2_mem_ops - memory handling/memory allocator operations
  26 * @alloc:      allocate video memory and, optionally, allocator private data,
  27 *              return NULL on failure or a pointer to allocator private,
  28 *              per-buffer data on success; the returned private structure
  29 *              will then be passed as buf_priv argument to other ops in this
  30 *              structure
  31 * @put:        inform the allocator that the buffer will no longer be used;
  32 *              usually will result in the allocator freeing the buffer (if
  33 *              no other users of this buffer are present); the buf_priv
  34 *              argument is the allocator private per-buffer structure
  35 *              previously returned from the alloc callback
  36 * @get_userptr: acquire userspace memory for a hardware operation; used for
  37 *               USERPTR memory types; vaddr is the address passed to the
  38 *               videobuf layer when queuing a video buffer of USERPTR type;
  39 *               should return an allocator private per-buffer structure
  40 *               associated with the buffer on success, NULL on failure;
  41 *               the returned private structure will then be passed as buf_priv
  42 *               argument to other ops in this structure
  43 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
  44 *               be used
  45 * @attach_dmabuf: attach a shared struct dma_buf for a hardware operation;
  46 *                 used for DMABUF memory types; alloc_ctx is the alloc context
  47 *                 dbuf is the shared dma_buf; returns NULL on failure;
  48 *                 allocator private per-buffer structure on success;
  49 *                 this needs to be used for further accesses to the buffer
  50 * @detach_dmabuf: inform the exporter of the buffer that the current DMABUF
  51 *                 buffer is no longer used; the buf_priv argument is the
  52 *                 allocator private per-buffer structure previously returned
  53 *                 from the attach_dmabuf callback
  54 * @map_dmabuf: request for access to the dmabuf from allocator; the allocator
  55 *              of dmabuf is informed that this driver is going to use the
  56 *              dmabuf
  57 * @unmap_dmabuf: releases access control to the dmabuf - allocator is notified
  58 *                that this driver is done using the dmabuf for now
  59 * @prepare:    called every time the buffer is passed from userspace to the
  60 *              driver, useful for cache synchronisation, optional
  61 * @finish:     called every time the buffer is passed back from the driver
  62 *              to the userspace, also optional
  63 * @vaddr:      return a kernel virtual address to a given memory buffer
  64 *              associated with the passed private structure or NULL if no
  65 *              such mapping exists
  66 * @cookie:     return allocator specific cookie for a given memory buffer
  67 *              associated with the passed private structure or NULL if not
  68 *              available
  69 * @num_users:  return the current number of users of a memory buffer;
  70 *              return 1 if the videobuf layer (or actually the driver using
  71 *              it) is the only user
  72 * @mmap:       setup a userspace mapping for a given memory buffer under
  73 *              the provided virtual memory region
  74 *
  75 * Required ops for USERPTR types: get_userptr, put_userptr.
  76 * Required ops for MMAP types: alloc, put, num_users, mmap.
  77 * Required ops for read/write access types: alloc, put, num_users, vaddr
  78 * Required ops for DMABUF types: attach_dmabuf, detach_dmabuf, map_dmabuf,
  79 *                                unmap_dmabuf.
  80 */
  81struct vb2_mem_ops {
  82        void            *(*alloc)(void *alloc_ctx, unsigned long size);
  83        void            (*put)(void *buf_priv);
  84        struct dma_buf *(*get_dmabuf)(void *buf_priv);
  85
  86        void            *(*get_userptr)(void *alloc_ctx, unsigned long vaddr,
  87                                        unsigned long size, int write);
  88        void            (*put_userptr)(void *buf_priv);
  89
  90        void            (*prepare)(void *buf_priv);
  91        void            (*finish)(void *buf_priv);
  92
  93        void            *(*attach_dmabuf)(void *alloc_ctx, struct dma_buf *dbuf,
  94                                unsigned long size, int write);
  95        void            (*detach_dmabuf)(void *buf_priv);
  96        int             (*map_dmabuf)(void *buf_priv);
  97        void            (*unmap_dmabuf)(void *buf_priv);
  98
  99        void            *(*vaddr)(void *buf_priv);
 100        void            *(*cookie)(void *buf_priv);
 101
 102        unsigned int    (*num_users)(void *buf_priv);
 103
 104        int             (*mmap)(void *buf_priv, struct vm_area_struct *vma);
 105};
 106
 107struct vb2_plane {
 108        void                    *mem_priv;
 109        struct dma_buf          *dbuf;
 110        unsigned int            dbuf_mapped;
 111};
 112
 113/**
 114 * enum vb2_io_modes - queue access methods
 115 * @VB2_MMAP:           driver supports MMAP with streaming API
 116 * @VB2_USERPTR:        driver supports USERPTR with streaming API
 117 * @VB2_READ:           driver supports read() style access
 118 * @VB2_WRITE:          driver supports write() style access
 119 * @VB2_DMABUF:         driver supports DMABUF with streaming API
 120 */
 121enum vb2_io_modes {
 122        VB2_MMAP        = (1 << 0),
 123        VB2_USERPTR     = (1 << 1),
 124        VB2_READ        = (1 << 2),
 125        VB2_WRITE       = (1 << 3),
 126        VB2_DMABUF      = (1 << 4),
 127};
 128
 129/**
 130 * enum vb2_fileio_flags - flags for selecting a mode of the file io emulator,
 131 * by default the 'streaming' style is used by the file io emulator
 132 * @VB2_FILEIO_READ_ONCE:       report EOF after reading the first buffer
 133 * @VB2_FILEIO_WRITE_IMMEDIATELY:       queue buffer after each write() call
 134 */
 135enum vb2_fileio_flags {
 136        VB2_FILEIO_READ_ONCE            = (1 << 0),
 137        VB2_FILEIO_WRITE_IMMEDIATELY    = (1 << 1),
 138};
 139
 140/**
 141 * enum vb2_buffer_state - current video buffer state
 142 * @VB2_BUF_STATE_DEQUEUED:     buffer under userspace control
 143 * @VB2_BUF_STATE_PREPARED:     buffer prepared in videobuf and by the driver
 144 * @VB2_BUF_STATE_QUEUED:       buffer queued in videobuf, but not in driver
 145 * @VB2_BUF_STATE_ACTIVE:       buffer queued in driver and possibly used
 146 *                              in a hardware operation
 147 * @VB2_BUF_STATE_DONE:         buffer returned from driver to videobuf, but
 148 *                              not yet dequeued to userspace
 149 * @VB2_BUF_STATE_ERROR:        same as above, but the operation on the buffer
 150 *                              has ended with an error, which will be reported
 151 *                              to the userspace when it is dequeued
 152 */
 153enum vb2_buffer_state {
 154        VB2_BUF_STATE_DEQUEUED,
 155        VB2_BUF_STATE_PREPARED,
 156        VB2_BUF_STATE_QUEUED,
 157        VB2_BUF_STATE_ACTIVE,
 158        VB2_BUF_STATE_DONE,
 159        VB2_BUF_STATE_ERROR,
 160};
 161
 162struct vb2_queue;
 163
 164/**
 165 * struct vb2_buffer - represents a video buffer
 166 * @v4l2_buf:           struct v4l2_buffer associated with this buffer; can
 167 *                      be read by the driver and relevant entries can be
 168 *                      changed by the driver in case of CAPTURE types
 169 *                      (such as timestamp)
 170 * @v4l2_planes:        struct v4l2_planes associated with this buffer; can
 171 *                      be read by the driver and relevant entries can be
 172 *                      changed by the driver in case of CAPTURE types
 173 *                      (such as bytesused); NOTE that even for single-planar
 174 *                      types, the v4l2_planes[0] struct should be used
 175 *                      instead of v4l2_buf for filling bytesused - drivers
 176 *                      should use the vb2_set_plane_payload() function for that
 177 * @vb2_queue:          the queue to which this driver belongs
 178 * @num_planes:         number of planes in the buffer
 179 *                      on an internal driver queue
 180 * @state:              current buffer state; do not change
 181 * @queued_entry:       entry on the queued buffers list, which holds all
 182 *                      buffers queued from userspace
 183 * @done_entry:         entry on the list that stores all buffers ready to
 184 *                      be dequeued to userspace
 185 * @planes:             private per-plane information; do not change
 186 */
 187struct vb2_buffer {
 188        struct v4l2_buffer      v4l2_buf;
 189        struct v4l2_plane       v4l2_planes[VIDEO_MAX_PLANES];
 190
 191        struct vb2_queue        *vb2_queue;
 192
 193        unsigned int            num_planes;
 194
 195/* Private: internal use only */
 196        enum vb2_buffer_state   state;
 197
 198        struct list_head        queued_entry;
 199        struct list_head        done_entry;
 200
 201        struct vb2_plane        planes[VIDEO_MAX_PLANES];
 202};
 203
 204/**
 205 * struct vb2_ops - driver-specific callbacks
 206 *
 207 * @queue_setup:        called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS
 208 *                      handlers before memory allocation, or, if
 209 *                      *num_planes != 0, after the allocation to verify a
 210 *                      smaller number of buffers. Driver should return
 211 *                      the required number of buffers in *num_buffers, the
 212 *                      required number of planes per buffer in *num_planes; the
 213 *                      size of each plane should be set in the sizes[] array
 214 *                      and optional per-plane allocator specific context in the
 215 *                      alloc_ctxs[] array. When called from VIDIOC_REQBUFS,
 216 *                      fmt == NULL, the driver has to use the currently
 217 *                      configured format and *num_buffers is the total number
 218 *                      of buffers, that are being allocated. When called from
 219 *                      VIDIOC_CREATE_BUFS, fmt != NULL and it describes the
 220 *                      target frame format. In this case *num_buffers are being
 221 *                      allocated additionally to q->num_buffers.
 222 * @wait_prepare:       release any locks taken while calling vb2 functions;
 223 *                      it is called before an ioctl needs to wait for a new
 224 *                      buffer to arrive; required to avoid a deadlock in
 225 *                      blocking access type
 226 * @wait_finish:        reacquire all locks released in the previous callback;
 227 *                      required to continue operation after sleeping while
 228 *                      waiting for a new buffer to arrive
 229 * @buf_init:           called once after allocating a buffer (in MMAP case)
 230 *                      or after acquiring a new USERPTR buffer; drivers may
 231 *                      perform additional buffer-related initialization;
 232 *                      initialization failure (return != 0) will prevent
 233 *                      queue setup from completing successfully; optional
 234 * @buf_prepare:        called every time the buffer is queued from userspace
 235 *                      and from the VIDIOC_PREPARE_BUF ioctl; drivers may
 236 *                      perform any initialization required before each hardware
 237 *                      operation in this callback; if an error is returned, the
 238 *                      buffer will not be queued in driver; optional
 239 * @buf_finish:         called before every dequeue of the buffer back to
 240 *                      userspace; drivers may perform any operations required
 241 *                      before userspace accesses the buffer; optional
 242 * @buf_cleanup:        called once before the buffer is freed; drivers may
 243 *                      perform any additional cleanup; optional
 244 * @start_streaming:    called once to enter 'streaming' state; the driver may
 245 *                      receive buffers with @buf_queue callback before
 246 *                      @start_streaming is called; the driver gets the number
 247 *                      of already queued buffers in count parameter; driver
 248 *                      can return an error if hardware fails or not enough
 249 *                      buffers has been queued, in such case all buffers that
 250 *                      have been already given by the @buf_queue callback are
 251 *                      invalidated.
 252 * @stop_streaming:     called when 'streaming' state must be disabled; driver
 253 *                      should stop any DMA transactions or wait until they
 254 *                      finish and give back all buffers it got from buf_queue()
 255 *                      callback; may use vb2_wait_for_all_buffers() function
 256 * @buf_queue:          passes buffer vb to the driver; driver may start
 257 *                      hardware operation on this buffer; driver should give
 258 *                      the buffer back by calling vb2_buffer_done() function;
 259 *                      it is allways called after calling STREAMON ioctl;
 260 *                      might be called before start_streaming callback if user
 261 *                      pre-queued buffers before calling STREAMON
 262 */
 263struct vb2_ops {
 264        int (*queue_setup)(struct vb2_queue *q, const struct v4l2_format *fmt,
 265                           unsigned int *num_buffers, unsigned int *num_planes,
 266                           unsigned int sizes[], void *alloc_ctxs[]);
 267
 268        void (*wait_prepare)(struct vb2_queue *q);
 269        void (*wait_finish)(struct vb2_queue *q);
 270
 271        int (*buf_init)(struct vb2_buffer *vb);
 272        int (*buf_prepare)(struct vb2_buffer *vb);
 273        int (*buf_finish)(struct vb2_buffer *vb);
 274        void (*buf_cleanup)(struct vb2_buffer *vb);
 275
 276        int (*start_streaming)(struct vb2_queue *q, unsigned int count);
 277        int (*stop_streaming)(struct vb2_queue *q);
 278
 279        void (*buf_queue)(struct vb2_buffer *vb);
 280};
 281
 282struct v4l2_fh;
 283
 284/**
 285 * struct vb2_queue - a videobuf queue
 286 *
 287 * @type:       queue type (see V4L2_BUF_TYPE_* in linux/videodev2.h
 288 * @io_modes:   supported io methods (see vb2_io_modes enum)
 289 * @io_flags:   additional io flags (see vb2_fileio_flags enum)
 290 * @lock:       pointer to a mutex that protects the vb2_queue struct. The
 291 *              driver can set this to a mutex to let the v4l2 core serialize
 292 *              the queuing ioctls. If the driver wants to handle locking
 293 *              itself, then this should be set to NULL. This lock is not used
 294 *              by the videobuf2 core API.
 295 * @owner:      The filehandle that 'owns' the buffers, i.e. the filehandle
 296 *              that called reqbufs, create_buffers or started fileio.
 297 *              This field is not used by the videobuf2 core API, but it allows
 298 *              drivers to easily associate an owner filehandle with the queue.
 299 * @ops:        driver-specific callbacks
 300 * @mem_ops:    memory allocator specific callbacks
 301 * @drv_priv:   driver private data
 302 * @buf_struct_size: size of the driver-specific buffer structure;
 303 *              "0" indicates the driver doesn't want to use a custom buffer
 304 *              structure type, so sizeof(struct vb2_buffer) will is used
 305 *
 306 * @memory:     current memory type used
 307 * @bufs:       videobuf buffer structures
 308 * @num_buffers: number of allocated/used buffers
 309 * @queued_list: list of buffers currently queued from userspace
 310 * @queued_count: number of buffers owned by the driver
 311 * @done_list:  list of buffers ready to be dequeued to userspace
 312 * @done_lock:  lock to protect done_list list
 313 * @done_wq:    waitqueue for processes waiting for buffers ready to be dequeued
 314 * @alloc_ctx:  memory type/allocator-specific contexts for each plane
 315 * @streaming:  current streaming state
 316 * @fileio:     file io emulator internal data, used only if emulator is active
 317 */
 318struct vb2_queue {
 319        enum v4l2_buf_type              type;
 320        unsigned int                    io_modes;
 321        unsigned int                    io_flags;
 322        struct mutex                    *lock;
 323        struct v4l2_fh                  *owner;
 324
 325        const struct vb2_ops            *ops;
 326        const struct vb2_mem_ops        *mem_ops;
 327        void                            *drv_priv;
 328        unsigned int                    buf_struct_size;
 329
 330/* private: internal use only */
 331        enum v4l2_memory                memory;
 332        struct vb2_buffer               *bufs[VIDEO_MAX_FRAME];
 333        unsigned int                    num_buffers;
 334
 335        struct list_head                queued_list;
 336
 337        atomic_t                        queued_count;
 338        struct list_head                done_list;
 339        spinlock_t                      done_lock;
 340        wait_queue_head_t               done_wq;
 341
 342        void                            *alloc_ctx[VIDEO_MAX_PLANES];
 343        unsigned int                    plane_sizes[VIDEO_MAX_PLANES];
 344
 345        unsigned int                    streaming:1;
 346
 347        struct vb2_fileio_data          *fileio;
 348};
 349
 350void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
 351void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no);
 352
 353void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
 354int vb2_wait_for_all_buffers(struct vb2_queue *q);
 355
 356int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
 357int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
 358
 359int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create);
 360int vb2_prepare_buf(struct vb2_queue *q, struct v4l2_buffer *b);
 361
 362int __must_check vb2_queue_init(struct vb2_queue *q);
 363
 364void vb2_queue_release(struct vb2_queue *q);
 365
 366int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
 367int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb);
 368int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
 369
 370int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
 371int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
 372
 373int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
 374#ifndef CONFIG_MMU
 375unsigned long vb2_get_unmapped_area(struct vb2_queue *q,
 376                                    unsigned long addr,
 377                                    unsigned long len,
 378                                    unsigned long pgoff,
 379                                    unsigned long flags);
 380#endif
 381unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
 382size_t vb2_read(struct vb2_queue *q, char __user *data, size_t count,
 383                loff_t *ppos, int nonblock);
 384size_t vb2_write(struct vb2_queue *q, char __user *data, size_t count,
 385                loff_t *ppos, int nonblock);
 386
 387/**
 388 * vb2_is_streaming() - return streaming status of the queue
 389 * @q:          videobuf queue
 390 */
 391static inline bool vb2_is_streaming(struct vb2_queue *q)
 392{
 393        return q->streaming;
 394}
 395
 396/**
 397 * vb2_is_busy() - return busy status of the queue
 398 * @q:          videobuf queue
 399 *
 400 * This function checks if queue has any buffers allocated.
 401 */
 402static inline bool vb2_is_busy(struct vb2_queue *q)
 403{
 404        return (q->num_buffers > 0);
 405}
 406
 407/**
 408 * vb2_get_drv_priv() - return driver private data associated with the queue
 409 * @q:          videobuf queue
 410 */
 411static inline void *vb2_get_drv_priv(struct vb2_queue *q)
 412{
 413        return q->drv_priv;
 414}
 415
 416/**
 417 * vb2_set_plane_payload() - set bytesused for the plane plane_no
 418 * @vb:         buffer for which plane payload should be set
 419 * @plane_no:   plane number for which payload should be set
 420 * @size:       payload in bytes
 421 */
 422static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
 423                                 unsigned int plane_no, unsigned long size)
 424{
 425        if (plane_no < vb->num_planes)
 426                vb->v4l2_planes[plane_no].bytesused = size;
 427}
 428
 429/**
 430 * vb2_get_plane_payload() - get bytesused for the plane plane_no
 431 * @vb:         buffer for which plane payload should be set
 432 * @plane_no:   plane number for which payload should be set
 433 * @size:       payload in bytes
 434 */
 435static inline unsigned long vb2_get_plane_payload(struct vb2_buffer *vb,
 436                                 unsigned int plane_no)
 437{
 438        if (plane_no < vb->num_planes)
 439                return vb->v4l2_planes[plane_no].bytesused;
 440        return 0;
 441}
 442
 443/**
 444 * vb2_plane_size() - return plane size in bytes
 445 * @vb:         buffer for which plane size should be returned
 446 * @plane_no:   plane number for which size should be returned
 447 */
 448static inline unsigned long
 449vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
 450{
 451        if (plane_no < vb->num_planes)
 452                return vb->v4l2_planes[plane_no].length;
 453        return 0;
 454}
 455
 456/*
 457 * The following functions are not part of the vb2 core API, but are simple
 458 * helper functions that you can use in your struct v4l2_file_operations,
 459 * struct v4l2_ioctl_ops and struct vb2_ops. They will serialize if vb2_queue->lock
 460 * or video_device->lock is set, and they will set and test vb2_queue->owner
 461 * to check if the calling filehandle is permitted to do the queuing operation.
 462 */
 463
 464/* struct v4l2_ioctl_ops helpers */
 465
 466int vb2_ioctl_reqbufs(struct file *file, void *priv,
 467                          struct v4l2_requestbuffers *p);
 468int vb2_ioctl_create_bufs(struct file *file, void *priv,
 469                          struct v4l2_create_buffers *p);
 470int vb2_ioctl_prepare_buf(struct file *file, void *priv,
 471                          struct v4l2_buffer *p);
 472int vb2_ioctl_querybuf(struct file *file, void *priv, struct v4l2_buffer *p);
 473int vb2_ioctl_qbuf(struct file *file, void *priv, struct v4l2_buffer *p);
 474int vb2_ioctl_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p);
 475int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i);
 476int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i);
 477int vb2_ioctl_expbuf(struct file *file, void *priv,
 478        struct v4l2_exportbuffer *p);
 479
 480/* struct v4l2_file_operations helpers */
 481
 482int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
 483int vb2_fop_release(struct file *file);
 484ssize_t vb2_fop_write(struct file *file, char __user *buf,
 485                size_t count, loff_t *ppos);
 486ssize_t vb2_fop_read(struct file *file, char __user *buf,
 487                size_t count, loff_t *ppos);
 488unsigned int vb2_fop_poll(struct file *file, poll_table *wait);
 489#ifndef CONFIG_MMU
 490unsigned long vb2_fop_get_unmapped_area(struct file *file, unsigned long addr,
 491                unsigned long len, unsigned long pgoff, unsigned long flags);
 492#endif
 493
 494/* struct vb2_ops helpers, only use if vq->lock is non-NULL. */
 495
 496void vb2_ops_wait_prepare(struct vb2_queue *vq);
 497void vb2_ops_wait_finish(struct vb2_queue *vq);
 498
 499#endif /* _MEDIA_VIDEOBUF2_CORE_H */
 500
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