/* SPDX-License-Identifier: BSD-2-Clause */ /* * Copyright (C) 2019, Raspberry Pi (Trading) Limited * * cam_helper.hpp - helper class providing camera information */ #pragma once #include #include "camera_mode.h" #include "md_parser.hpp" #include "libcamera/internal/v4l2_videodevice.h" namespace RPiController { // The CamHelper class provides a number of facilities that anyone trying // trying to drive a camera will need to know, but which are not provided by // by the standard driver framework. Specifically, it provides: // // A "CameraMode" structure to describe extra information about the chosen // mode of the driver. For example, how it is cropped from the full sensor // area, how it is scaled, whether pixels are averaged compared to the full // resolution. // // The ability to convert between number of lines of exposure and actual // exposure time, and to convert between the sensor's gain codes and actual // gains. // // A method to return the number of frames of delay between updating exposure // and analogue gain and the changes taking effect. For many sensors these // take the values 2 and 1 respectively, but sensors that are different will // need to over-ride the default method provided. // // A method to query if the sensor outputs embedded data that can be parsed. // // A parser to parse the metadata buffers provided by some sensors (for // example, the imx219 does; the ov5647 doesn't). This allows us to know for // sure the exposure and gain of the frame we're looking at. CamHelper // provides methods for converting analogue gains to and from the sensor's // native gain codes. // // Finally, a set of methods that determine how to handle the vagaries of // different camera modules on start-up or when switching modes. Some // modules may produce one or more frames that are not yet correctly exposed, // or where the metadata may be suspect. We have the following methods: // HideFramesStartup(): Tell the pipeline handler not to return this many // frames at start-up. This can also be used to hide initial frames // while the AGC and other algorithms are sorting themselves out. // HideFramesModeSwitch(): Tell the pipeline handler not to return this // many frames after a mode switch (other than start-up). Some sensors // may produce innvalid frames after a mode switch; others may not. // MistrustFramesStartup(): At start-up a sensor may return frames for // which we should not run any control algorithms (for example, metadata // may be invalid). // MistrustFramesModeSwitch(): The number of frames, after a mode switch // (other than start-up), for which control algorithms should not run // (for example, metadata may be unreliable). class CamHelper { public: static CamHelper *Create(std::string const &cam_name); CamHelper(MdParser *parser); virtual ~CamHelper(); void SetCameraMode(const CameraMode &mode); MdParser &Parser() const { return *parser_; } uint32_t ExposureLines(double exposure_us) const; double Exposure(uint32_t exposure_lines) const; // in us virtual uint32_t GainCode(double gain) const = 0; virtual double Gain(uint32_t gain_code) const = 0; virtual void GetDelays(int &exposure_delay, int &gain_delay) const; virtual bool SensorEmbeddedDataPresent() const; virtual unsigned int HideFramesStartup() const; virtual unsigned int HideFramesModeSwitch() const; virtual unsigned int MistrustFramesStartup() const; virtual unsigned int MistrustFramesModeSwitch() const; protected: MdParser *parser_; CameraMode mode_; bool initialized_; }; // This is for registering camera helpers with the system, so that the // CamHelper::Create function picks them up automatically. typedef CamHelper *(*CamHelperCreateFunc)(); struct RegisterCamHelper { RegisterCamHelper(char const *cam_name, CamHelperCreateFunc create_func); }; } // namespace RPi 2'>22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018, Google Inc.
 *
 * camera.cpp - Camera device
 */

#include <libcamera/camera.h>

#include <atomic>
#include <iomanip>

#include <libcamera/framebuffer_allocator.h>
#include <libcamera/request.h>
#include <libcamera/stream.h>

#include "libcamera/internal/log.h"
#include "libcamera/internal/pipeline_handler.h"
#include "libcamera/internal/utils.h"

/**
 * \file camera.h
 * \brief Camera device handling
 *
 * At the core of libcamera is the camera device, combining one image source
 * with processing hardware able to provide one or multiple image streams. The
 * Camera class represents a camera device.
 *
 * A camera device contains a single image source, and separate camera device
 * instances relate to different image sources. For instance, a phone containing
 * front and back image sensors will be modelled with two camera devices, one
 * for each sensor. When multiple streams can be produced from the same image
 * source, all those streams are guaranteed to be part of the same camera
 * device.
 *
 * While not sharing image sources, separate camera devices can share other
 * system resources, such as an ISP. For this reason camera device instances may
 * not be fully independent, in which case usage restrictions may apply. For
 * instance, a phone with a front and a back camera device may not allow usage
 * of the two devices simultaneously.
 */

namespace libcamera {

LOG_DECLARE_CATEGORY(Camera)

/**
 * \class CameraConfiguration
 * \brief Hold configuration for streams of the camera

 * The CameraConfiguration holds an ordered list of stream configurations. It
 * supports iterators and operates as a vector of StreamConfiguration instances.
 * The stream configurations are inserted by addConfiguration(), and the
 * operator[](int) returns a reference to the StreamConfiguration based on its
 * insertion index. Accessing a stream configuration with an invalid index
 * results in undefined behaviour.
 *
 * CameraConfiguration instances are retrieved from the camera with
 * Camera::generateConfiguration(). Applications may then inspect the
 * configuration, modify it, and possibly add new stream configuration entries
 * with addConfiguration(). Once the camera configuration satisfies the
 * application, it shall be validated by a call to validate(). The validation
 * implements "try" semantics: it adjusts invalid configurations to the closest
 * achievable parameters instead of rejecting them completely. Applications
 * then decide whether to accept the modified configuration, or try again with
 * a different set of parameters. Once the configuration is valid, it is passed
 * to Camera::configure().
 */

/**
 * \enum CameraConfiguration::Status
 * \brief Validity of a camera configuration
 * \var CameraConfiguration::Valid
 * The configuration is fully valid
 * \var CameraConfiguration::Adjusted
 * The configuration has been adjusted to a valid configuration
 * \var CameraConfiguration::Invalid
 * The configuration is invalid and can't be adjusted automatically
 */

/**
 * \typedef CameraConfiguration::iterator
 * \brief Iterator for the stream configurations in the camera configuration
 */

/**
 * \typedef CameraConfiguration::const_iterator
 * \brief Const iterator for the stream configuration in the camera
 * configuration
 */

/**
 * \brief Create an empty camera configuration
 */
CameraConfiguration::CameraConfiguration()
	: config_({})
{
}

CameraConfiguration::~CameraConfiguration()
{
}

/**
 * \brief Add a stream configuration to the camera configuration
 * \param[in] cfg The stream configuration
 */
void CameraConfiguration::addConfiguration(const StreamConfiguration &cfg)
{
	config_.push_back(cfg);
}

/**
 * \fn CameraConfiguration::validate()
 * \brief Validate and possibly adjust the camera configuration
 *
 * This method adjusts the camera configuration to the closest valid
 * configuration and returns the validation status.
 *
 * \todo: Define exactly when to return each status code. Should stream
 * parameters set to 0 by the caller be adjusted without returning Adjusted ?
 * This would potentially be useful for applications but would get in the way
 * in Camera::configure(). Do we need an extra status code to signal this ?
 *
 * \todo: Handle validation of buffers count when refactoring the buffers API.
 *
 * \return A CameraConfiguration::Status value that describes the validation
 * status.
 * \retval CameraConfiguration::Invalid The configuration is invalid and can't
 * be adjusted. This may only occur in extreme cases such as when the
 * configuration is empty.
 * \retval CameraConfigutation::Adjusted The configuration has been adjusted
 * and is now valid. Parameters may have changed for any stream, and stream
 * configurations may have been removed. The caller shall check the
 * configuration carefully.
 * \retval CameraConfiguration::Valid The configuration was already valid and
 * hasn't been adjusted.
 */

/**
 * \brief Retrieve a reference to a stream configuration
 * \param[in] index Numerical index
 *
 * The \a index represents the zero based insertion order of stream
 * configuration into the camera configuration with addConfiguration(). Calling
 * this method with an invalid index results in undefined behaviour.
 *
 * \return The stream configuration
 */
StreamConfiguration &CameraConfiguration::at(unsigned int index)
{
	return config_[index];
}

/**
 * \brief Retrieve a const reference to a stream configuration
 * \param[in] index Numerical index
 *
 * The \a index represents the zero based insertion order of stream
 * configuration into the camera configuration with addConfiguration(). Calling
 * this method with an invalid index results in undefined behaviour.
 *
 * \return The stream configuration
 */
const StreamConfiguration &CameraConfiguration::at(unsigned int index) const
{
	return config_[index];
}

/**
 * \fn StreamConfiguration &CameraConfiguration::operator[](unsigned int)
 * \brief Retrieve a reference to a stream configuration
 * \param[in] index Numerical index
 *
 * The \a index represents the zero based insertion order of stream
 * configuration into the camera configuration with addConfiguration(). Calling
 * this method with an invalid index results in undefined behaviour.
 *
 * \return The stream configuration
 */

/**
 * \fn const StreamConfiguration &CameraConfiguration::operator[](unsigned int) const
 * \brief Retrieve a const reference to a stream configuration
 * \param[in] index Numerical index
 *
 * The \a index represents the zero based insertion order of stream
 * configuration into the camera configuration with addConfiguration(). Calling
 * this method with an invalid index results in undefined behaviour.
 *
 * \return The stream configuration
 */

/**
 * \brief Retrieve an iterator to the first stream configuration in the
 * sequence
 * \return An iterator to the first stream configuration
 */
CameraConfiguration::iterator CameraConfiguration::begin()
{
	return config_.begin();
}

/**
 * \brief Retrieve a const iterator to the first element of the stream
 * configurations
 * \return A const iterator to the first stream configuration
 */
CameraConfiguration::const_iterator CameraConfiguration::begin() const
{
	return config_.begin();
}

/**
 * \brief Retrieve an iterator pointing to the past-the-end stream
 * configuration in the sequence
 * \return An iterator to the element following the last stream configuration
 */
CameraConfiguration::iterator CameraConfiguration::end()
{
	return config_.end();
}

/**
 * \brief Retrieve a const iterator pointing to the past-the-end stream
 * configuration in the sequence
 * \return A const iterator to the element following the last stream
 * configuration
 */
CameraConfiguration::const_iterator CameraConfiguration::end() const
{
	return config_.end();
}

/**
 * \brief Check if the camera configuration is empty
 * \return True if the configuration is empty
 */
bool CameraConfiguration::empty() const
{
	return config_.empty();
}

/**
 * \brief Retrieve the number of stream configurations
 * \return Number of stream configurations
 */
std::size_t CameraConfiguration::size() const
{
	return config_.size();
}

/**
 * \var CameraConfiguration::config_
 * \brief The vector of stream configurations
 */

class Camera::Private
{
public:
	enum State {
		CameraAvailable,
		CameraAcquired,
		CameraConfigured,
		CameraRunning,
	};

	Private(PipelineHandler *pipe, const std::string &name,
		const std::set<Stream *> &streams);
	~Private();

	int isAccessAllowed(State state, bool allowDisconnected = false) const;
	int isAccessAllowed(State low, State high,
			    bool allowDisconnected = false) const;

	void disconnect();
	void setState(State state);

	std::shared_ptr<PipelineHandler> pipe_;
	std::string name_;
	std::set<Stream *> streams_;
	std::set<Stream *> activeStreams_;

private:
	bool disconnected_;
	std::atomic<State> state_;
};

Camera::Private::Private(PipelineHandler *pipe, const std::string &name,
			 const std::set<Stream *> &streams)
	: pipe_(pipe->shared_from_this()), name_(name), streams_(streams),
	  disconnected_(false), state_(CameraAvailable)
{
}

Camera::Private::~Private()
{
	if (state_.load(std::memory_order_acquire) != Private::CameraAvailable)
		LOG(Camera, Error) << "Removing camera while still in use";
}

static const char *const camera_state_names[] = {
	"Available",
	"Acquired",
	"Configured",
	"Running",
};

int Camera::Private::isAccessAllowed(State state, bool allowDisconnected) const
{
	if (!allowDisconnected && disconnected_)
		return -ENODEV;

	State currentState = state_.load(std::memory_order_acquire);
	if (currentState == state)
		return 0;

	ASSERT(static_cast<unsigned int>(state) < ARRAY_SIZE(camera_state_names));

	LOG(Camera, Debug) << "Camera in " << camera_state_names[currentState]
			   << " state trying operation requiring state "
			   << camera_state_names[state];

	return -EACCES;
}

int Camera::Private::isAccessAllowed(State low, State high,
				     bool allowDisconnected) const
{
	if (!allowDisconnected && disconnected_)
		return -ENODEV;

	State currentState = state_.load(std::memory_order_acquire);
	if (currentState >= low && currentState <= high)
		return 0;

	ASSERT(static_cast<unsigned int>(low) < ARRAY_SIZE(camera_state_names) &&
	       static_cast<unsigned int>(high) < ARRAY_SIZE(camera_state_names));

	LOG(Camera, Debug) << "Camera in " << camera_state_names[currentState]
			   << " state trying operation requiring state between "
			   << camera_state_names[low] << " and "
			   << camera_state_names[high];

	return -EACCES;
}

void Camera::Private::disconnect()
{
	/*
	 * If the camera was running when the hardware was removed force the
	 * state to Configured state to allow applications to free resources
	 * and call release() before deleting the camera.
	 */
	if (state_.load(std::memory_order_acquire) == Private::CameraRunning)
		state_.store(Private::CameraConfigured, std::memory_order_release);

	disconnected_ = true;
}

void Camera::Private::setState(State state)
{
	state_.store(state, std::memory_order_release);
}

/**
 * \class Camera
 * \brief Camera device
 *
 * \todo Add documentation for camera start timings. What exactly does the
 * camera expect the pipeline handler to do when start() is called?
 *
 * The Camera class models a camera capable of producing one or more image
 * streams from a single image source. It provides the main interface to
 * configuring and controlling the device, and capturing image streams. It is
 * the central object exposed by libcamera.
 *
 * To support the central nature of Camera objects, libcamera manages the
 * lifetime of camera instances with std::shared_ptr<>. Instances shall be
 * created with the create() function which returns a shared pointer. The
 * Camera constructors and destructor are private, to prevent instances from
 * being constructed and destroyed manually.
 *
 * \section camera_operation Operating the Camera
 *
 * An application needs to perform a sequence of operations on a camera before
 * it is ready to process requests. The camera needs to be acquired and
 * configured to prepare the camera for capture. Once started the camera can
 * process requests until it is stopped. When an application is done with a
 * camera, the camera needs to be released.
 *
 * An application may start and stop a camera multiple times as long as it is
 * not released. The camera may also be reconfigured.
 *
 * Functions that affect the camera state as defined below are generally not
 * synchronized with each other by the Camera class. The caller is responsible
 * for ensuring their synchronization if necessary.
 *
 * \subsection Camera States
 *
 * To help manage the sequence of operations needed to control the camera a set
 * of states are defined. Each state describes which operations may be performed
 * on the camera. Performing an operation not allowed in the camera state
 * results in undefined behaviour. Operations not listed at all in the state
 * diagram are allowed in all states.
 *
 * \dot
 * digraph camera_state_machine {
 *   node [shape = doublecircle ]; Available;
 *   node [shape = circle ]; Acquired;
 *   node [shape = circle ]; Configured;
 *   node [shape = circle ]; Running;
 *
 *   Available -> Available [label = "release()"];
 *   Available -> Acquired [label = "acquire()"];
 *
 *   Acquired -> Available [label = "release()"];
 *   Acquired -> Configured [label = "configure()"];
 *
 *   Configured -> Available [label = "release()"];
 *   Configured -> Configured [label = "configure(), createRequest()"];
 *   Configured -> Running [label = "start()"];
 *
 *   Running -> Configured [label = "stop()"];
 *   Running -> Running [label = "createRequest(), queueRequest()"];
 * }
 * \enddot
 *
 * \subsubsection Available
 * The base state of a camera, an application can inspect the properties of the
 * camera to determine if it wishes to use it. If an application wishes to use
 * a camera it should acquire() it to proceed to the Acquired state.
 *
 * \subsubsection Acquired
 * In the acquired state an application has exclusive access to the camera and
 * may modify the camera's parameters to configure it and proceed to the
 * Configured state.
 *
 * \subsubsection Configured
 * The camera is configured and ready to be started. The application may
 * release() the camera and to get back to the Available state or start()
 * it to progress to the Running state.
 *
 * \subsubsection Running
 * The camera is running and ready to process requests queued by the
 * application. The camera remains in this state until it is stopped and moved
 * to the Configured state.
 */

/**
 * \brief Create a camera instance
 * \param[in] pipe The pipeline handler responsible for the camera device
 * \param[in] name The name of the camera device
 * \param[in] streams Array of streams the camera provides
 *
 * The caller is responsible for guaranteeing unicity of the camera name.
 *
 * \return A shared pointer to the newly created camera object
 */
std::shared_ptr<Camera> Camera::create(PipelineHandler *pipe,
				       const std::string &name,
				       const std::set<Stream *> &streams)
{
	struct Deleter : std::default_delete<Camera> {
		void operator()(Camera *camera)
		{
			camera->deleteLater();
		}
	};

	Camera *camera = new Camera(pipe, name, streams);

	return std::shared_ptr<Camera>(camera, Deleter());
}

/**
 * \brief Retrieve the name of the camera
 * \context This function is \threadsafe.
 * \return Name of the camera device
 */
const std::string &Camera::name() const
{
	return p_->name_;
}

/**
 * \var Camera::bufferCompleted
 * \brief Signal emitted when a buffer for a request queued to the camera has
 * completed
 */

/**
 * \var Camera::requestCompleted
 * \brief Signal emitted when a request queued to the camera has completed
 */

/**
 * \var Camera::disconnected
 * \brief Signal emitted when the camera is disconnected from the system
 *
 * This signal is emitted when libcamera detects that the camera has been
 * removed from the system. For hot-pluggable devices this is usually caused by
 * physical device disconnection. The media device is passed as a parameter.
 *
 * As soon as this signal is emitted the camera instance will refuse all new
 * application API calls by returning errors immediately.
 */

Camera::Camera(PipelineHandler *pipe, const std::string &name,
	       const std::set<Stream *> &streams)
	: p_(new Private(pipe, name, streams))
{
}

Camera::~Camera()
{
}

/**
 * \brief Notify camera disconnection
 *
 * This method is used to notify the camera instance that the underlying
 * hardware has been unplugged. In response to the disconnection the camera
 * instance notifies the application by emitting the #disconnected signal, and
 * ensures that all new calls to the application-facing Camera API return an
 * error immediately.
 *
 * \todo Deal with pending requests if the camera is disconnected in a
 * running state.
 */
void Camera::disconnect()
{
	LOG(Camera, Debug) << "Disconnecting camera " << name();

	p_->disconnect();
	disconnected.emit(this);
}

int Camera::exportFrameBuffers(Stream *stream,
			       std::vector<std::unique_ptr<FrameBuffer>> *buffers)
{
	int ret = p_->isAccessAllowed(Private::CameraConfigured);
	if (ret < 0)
		return ret;

	if (streams().find(stream) == streams().end())
		return -EINVAL;

	if (p_->activeStreams_.find(stream) == p_->activeStreams_.end())
		return -EINVAL;

	return p_->pipe_->invokeMethod(&PipelineHandler::exportFrameBuffers,
				       ConnectionTypeBlocking, this, stream,
				       buffers);
}

/**
 * \brief Acquire the camera device for exclusive access
 *
 * After opening the device with open(), exclusive access must be obtained
 * before performing operations that change the device state. This function is
 * not blocking, if the device has already been acquired (by the same or another
 * process) the -EBUSY error code is returned.
 *
 * Acquiring a camera will limit usage of any other camera(s) provided by the
 * same pipeline handler to the same instance of libcamera. The limit is in
 * effect until all cameras from the pipeline handler are released. Other
 * instances of libcamera can still list and examine the cameras but will fail
 * if they attempt to acquire() any of them.
 *
 * Once exclusive access isn't needed anymore, the device should be released
 * with a call to the release() function.
 *
 * \context This function is \threadsafe. It may only be called when the camera
 * is in the Available state as defined in \ref camera_operation.
 *
 * \return 0 on success or a negative error code otherwise
 * \retval -ENODEV The camera has been disconnected from the system
 * \retval -EBUSY The camera is not free and can't be acquired by the caller
 */
int Camera::acquire()
{
	/*
	 * No manual locking is required as PipelineHandler::lock() is
	 * thread-safe.
	 */
	int ret = p_->isAccessAllowed(Private::CameraAvailable);
	if (ret < 0)
		return ret == -EACCES ? -EBUSY : ret;

	if (!p_->pipe_->lock()) {
		LOG(Camera, Info)
			<< "Pipeline handler in use by another process";
		return -EBUSY;
	}

	p_->setState(Private::CameraAcquired);

	return 0;
}

/**
 * \brief Release exclusive access to the camera device
 *
 * Releasing the camera device allows other users to acquire exclusive access
 * with the acquire() function.
 *
 * \context This function may only be called when the camera is in the
 * Available or Configured state as defined in \ref camera_operation, and shall
 * be synchronized by the caller with other functions that affect the camera
 * state.
 *
 * \return 0 on success or a negative error code otherwise
 * \retval -EBUSY The camera is running and can't be released
 */
int Camera::release()
{
	int ret = p_->isAccessAllowed(Private::CameraAvailable,
				      Private::CameraConfigured, true);
	if (ret < 0)
		return ret == -EACCES ? -EBUSY : ret;

	p_->pipe_->unlock();

	p_->setState(Private::CameraAvailable);

	return 0;
}

/**
 * \brief Retrieve the list of controls supported by the camera
 *
 * The list of controls supported by the camera and their associated
 * constraints remain constant through the lifetime of the Camera object.
 *
 * \context This function is \threadsafe.
 *
 * \return A ControlInfoMap listing the controls supported by the camera
 */
const ControlInfoMap &Camera::controls()
{
	return p_->pipe_->controls(this);
}

/**
 * \brief Retrieve the list of properties of the camera
 *
 * Camera properties are static information that describe the capabilities of
 * the camera. They remain constant through the lifetime of the Camera object.
 *
 * \return A ControlList of properties supported by the camera
 */
const ControlList &Camera::properties()
{
	return p_->pipe_->properties(this);
}

/**
 * \brief Retrieve all the camera's stream information