external_libcamera/src/libcamera/camera_sensor.cpp

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * camera_sensor.cpp - A camera sensor
 */

#include "libcamera/internal/camera_sensor.h"

#include <algorithm>
#include <float.h>
#include <iomanip>
#include <limits.h>
#include <math.h>
#include <regex>

#include <libcamera/property_ids.h>

#include "libcamera/internal/formats.h"
#include "libcamera/internal/utils.h"
#include "libcamera/internal/v4l2_subdevice.h"

/**
 * \file camera_sensor.h
 * \brief A camera sensor
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(CameraSensor);

/**
 * \struct CameraSensorInfo
 * \brief Report the image sensor characteristics
 *
 * The structure reports image sensor characteristics used by IPA modules to
 * tune their algorithms based on the image sensor model currently in use and
 * its configuration.
 *
 * The reported information describes the sensor's intrinsics characteristics,
 * such as its pixel array size and the sensor model name, as well as
 * information relative to the currently configured mode, such as the produced
 * image size and the bit depth of the requested image format.
 *
 * Instances of this structure are meant to be assembled by the CameraSensor
 * class by inspecting the sensor static properties as well as information
 * relative to the current configuration.
 */

/**
 * \var CameraSensorInfo::model
 * \brief The image sensor model name
 *
 * The sensor model name is a free-formed string that uniquely identifies the
 * sensor model.
 */

/**
 * \var CameraSensorInfo::bitsPerPixel
 * \brief The number of bits per pixel of the image format produced by the
 * image sensor
 */

/**
 * \var CameraSensorInfo::activeAreaSize
 * \brief The size of the pixel array active area of the sensor
 */

/**
 * \var CameraSensorInfo::analogCrop
 * \brief The portion of the pixel array active area which is read-out and
 * processed
 *
 * The analog crop rectangle top-left corner is defined as the displacement
 * from the top-left corner of the pixel array active area. The rectangle
 * horizontal and vertical sizes define the portion of the pixel array which
 * is read-out and provided to the sensor's internal processing pipeline, before
 * any pixel sub-sampling method, such as pixel binning, skipping and averaging
 * take place.
 */

/**
 * \var CameraSensorInfo::outputSize
 * \brief The size of the images produced by the camera sensor
 *
 * The output image size defines the horizontal and vertical sizes of the images
 * produced by the image sensor. The output image size is defined as the end
 * result of the sensor's internal image processing pipeline stages, applied on
 * the pixel array portion defined by the analog crop rectangle. Each image
 * processing stage that performs pixel sub-sampling techniques, such as pixel
 * binning or skipping, or perform any additional digital scaling concur in the
 * definition of the output image size.
 */

/**
 * \var CameraSensorInfo::pixelRate
 * \brief The number of pixels produced in a second
 *
 * To obtain the read-out time in seconds of a full line:
 *
 * \verbatim
	lineDuration(s) = lineLength(pixels) / pixelRate(pixels per second)
   \endverbatim
 */

/**
 * \var CameraSensorInfo::lineLength
 * \brief Total line length in pixels
 *
 * The total line length in pixel clock periods, including blanking.
 */

/**
 * \class CameraSensor
 * \brief A camera sensor based on V4L2 subdevices
 *
 * The CameraSensor class eases handling of sensors for pipeline handlers by
 * hiding the details of the V4L2 subdevice kernel API and caching sensor
 * information.
 *
 * The implementation is currently limited to sensors that expose a single V4L2
 * subdevice with a single pad. It will be extended to support more complex
 * devices as the needs arise.
 */

/**
 * \brief Construct a CameraSensor
 * \param[in] entity The media entity backing the camera sensor
 *
 * Once constructed the instance must be initialized with init().
 */
CameraSensor::CameraSensor(const MediaEntity *entity)
	: entity_(entity), pad_(UINT_MAX), properties_(properties::properties)
{
}

/**
 * \brief Destroy a CameraSensor
 */
CameraSensor::~CameraSensor()
{
}

/**
 * \brief Initialize the camera sensor instance
 *
 * This method performs the initialisation steps of the CameraSensor that may
 * fail. It shall be called once and only once after constructing the instance.
 *
 * \return 0 on success or a negative error code otherwise
 */
int CameraSensor::init()
{
	for (const MediaPad *pad : entity_->pads()) {
		if (pad->flags() & MEDIA_PAD_FL_SOURCE) {
			pad_ = pad->index();
			break;
		}
	}

	if (pad_ == UINT_MAX) {
		LOG(CameraSensor, Error)
			<< "Sensors with more than one pad are not supported";
		return -EINVAL;
	}

	if (entity_->function() != MEDIA_ENT_F_CAM_SENSOR) {
		LOG(CameraSensor, Error)
			<< "Invalid sensor function "
			<< utils::hex(entity_->function());
		return -EINVAL;
	}

	/*
	 * Extract the camera sensor model name from the media entity name.
	 *
	 * There is no standardized naming scheme for sensor entities in the
	 * Linux kernel at the moment.
	 *
	 * - The most common rule, used by I2C sensors, associates the model
	 *   name with the I2C bus number and address (e.g. 'imx219 0-0010').
	 *
	 * - When the sensor exposes multiple subdevs, the model name is
	 *   usually followed by a function name, as in the smiapp driver (e.g.
	 *   'jt8ew9 pixel_array 0-0010').
	 *
	 * - The vimc driver names its sensors 'Sensor A' and 'Sensor B'.
	 *
	 * Other schemes probably exist. As a best effort heuristic, use the
	 * part of the entity name before the first space if the name contains
	 * an I2C address, and use the full entity name otherwise.
	 */
	std::string entityName = entity_->name();
	std::regex i2cRegex{ " [0-9]+-[0-9a-f]{4}" };
	std::smatch match;

	if (std::regex_search(entityName, match, i2cRegex))
		model_ = entityName.substr(0, entityName.find(' '));
	else
		model_ = entityName;

	/* Create and open the subdev. */
	subdev_ = std::make_unique<V4L2Subdevice>(entity_);
	int ret = subdev_->open();
	if (ret < 0)
		return ret;

	/* Retrieve and store the camera sensor properties. */
	const ControlInfoMap &controls = subdev_->controls();
	int32_t propertyValue;

	/* Camera Location: default is front location. */
	const auto &orientation = controls.find(V4L2_CID_CAMERA_ORIENTATION);
	if (orientation != controls.end()) {
		int32_t v4l2Orientation = orientation->second.def().get<int32_t>();

		switch (v4l2Orientation) {
		default:
			LOG(CameraSensor, Warning)
				<< "Unsupported camera location "
				<< v4l2Orientation << ", setting to Front";
			/* Fall-through */
		case V4L2_CAMERA_ORIENTATION_FRONT:
			propertyValue = properties::CameraLocationFront;
			break;
		case V4L2_CAMERA_ORIENTATION_BACK:
			propertyValue = properties::CameraLocationBack;
			break;
		case V4L2_CAMERA_ORIENTATION_EXTERNAL:
			propertyValue = properties::CameraLocationExternal;
			break;
		}
	} else {
		propertyValue = properties::CameraLocationFront;
	}
	properties_.set(properties::Location, propertyValue);

	/* Camera Rotation: default is 0 degrees. */
	const auto &rotationControl = controls.find(V4L2_CID_CAMERA_SENSOR_ROTATION);
	if (rotationControl != controls.end())
		propertyValue = rotationControl->second.def().get<int32_t>();
	else
		propertyValue = 0;
	properties_.set(properties::Rotation, propertyValue);

	/* Enumerate, sort and cache media bus codes and sizes. */
	formats_ = subdev_->formats(pad_);
	if (formats_.isEmpty()) {
		LOG(CameraSensor, Error) << "No image format found";
		return -EINVAL;
	}

	mbusCodes_ = formats_.formats();
	std::sort(mbusCodes_.begin(), mbusCodes_.end());

	for (const auto &format : formats_.data()) {
		const std::vector<SizeRange> &ranges = format.second;
		std::transform(ranges.begin(), ranges.end(), std::back_inserter(sizes_),
			       [](const SizeRange &range) { return range.max; });
	}

	std::sort(sizes_.begin(), sizes_.end());

	/* Remove duplicates. */
	auto last = std::unique(sizes_.begin(), sizes_.end());
	sizes_.erase(last, sizes_.end());

	/*
	 * The sizes_ vector is sorted in ascending order, the resolution is
	 * thus the last element of the vector.
	 */
	resolution_ = sizes_.back();

	return 0;
}

/**
 * \fn CameraSensor::model()
 * \brief Retrieve the sensor model name
 *
 * The sensor model name is a free-formed string that uniquely identifies the
 * sensor model.
 *
 * \return The sensor model name
 */

/**
 * \fn CameraSensor::entity()
 * \brief Retrieve the sensor media entity
 * \return The sensor media entity
 */

/**
 * \fn CameraSensor::mbusCodes()
 * \brief Retrieve the media bus codes supported by the camera sensor
 * \return The supported media bus codes sorted in increasing order
 */

/**
 * \fn CameraSensor::sizes()
 * \brief Retrieve the frame sizes supported by the camera sensor
 *
 * The reported sizes span all media bus codes supported by the camera sensor.
 * Not all sizes may be supported by all media bus codes.
 *
 * \return The supported frame sizes sorted in increasing order
 */

/**
 * \fn CameraSensor::resolution()
 * \brief Retrieve the camera sensor resolution
 * \return The camera sensor resolution in pixels
 */

/**
 * \brief Retrieve the best sensor format for a desired output
 * \param[in] mbusCodes The list of acceptable media bus codes
 * \param[in] size The desired size
 *
 * Media bus codes are selected from \a mbusCodes, which lists all acceptable
 * codes in decreasing order of preference. Media bus codes supported by the
 * sensor but not listed in \a mbusCodes are ignored. If none of the desired
 * codes is supported, it returns an error.
 *
 * \a size indicates the desired size at the output of the sensor. This method
 * selects the best media bus code and size supported by the sensor according
 * to the following criteria.
 *
 * - The desired \a size shall fit in the sensor output size to avoid the need
 *   to up-scale.
 * - The sensor output size shall match the desired aspect ratio to avoid the
 *   need to crop the field of view.
 * - The sensor output size shall be as small as possible to lower the required
 *   bandwidth.
 * - The desired \a size shall be supported by one of the media bus code listed
 *   in \a mbusCodes.
 *
 * When multiple media bus codes can produce the same size, the code at the
 * lowest position in \a mbusCodes is selected.
 *
 * The use of this method is optional, as the above criteria may not match the
 * needs of all pipeline handlers. Pipeline handlers may implement custom
 * sensor format selection when needed.
 *
 * The returned sensor output format is guaranteed to be acceptable by the
 * setFormat() method without any modification.
 *
 * \return The best sensor output format matching the desired media bus codes
 * and size on success, or an empty format otherwise.
 */
V4L2SubdeviceFormat CameraSensor::getFormat(const std::vector<unsigned int> &mbusCodes,
					    const Size &size) const
{
	unsigned int desiredArea = size.width * size.height;
	unsigned int bestArea = UINT_MAX;
	float desiredRatio = static_cast<float>(size.width) / size.height;
	float bestRatio = FLT_MAX;
	const Size *bestSize = nullptr;
	uint32_t bestCode = 0;

	for (unsigned int code : mbusCodes) {
		const std::vector<SizeRange> &ranges = formats_.sizes(code);

		for (const SizeRange &range : ranges) {
			const Size &sz = range.max;

			if (sz.width < size.width || sz.height < size.height)
				continue;

			float ratio = static_cast<float>(sz.width) / sz.height;
			float ratioDiff = fabsf(ratio - desiredRatio);
			unsigned int area = sz.width * sz.height;
			unsigned int areaDiff = area - desiredArea;

			if (ratioDiff > bestRatio)
				continue;

			if (ratioDiff < bestRatio || areaDiff < bestArea) {
				bestRatio = ratioDiff;
				bestArea = areaDiff;
				bestSize = &sz;
				bestCode = code;
			}
		}
	}

	if (!bestSize) {
		LOG(CameraSensor, Debug) << "No supported format or size found";
		return {};
	}

	V4L2SubdeviceFormat format{
		.mbus_code = bestCode,
		.size = *bestSize,
	};

	return format;
}

/**
 * \brief Set the sensor output format
 * \param[in] format The desired sensor output format
 * \return 0 on success or a negative error code otherwise
 */
int CameraSensor::setFormat(V4L2SubdeviceFormat *format)
{
	return subdev_->setFormat(pad_, format);
}

/**
 * \brief Retrieve the supported V4L2 controls and their information
 * \return A map of the V4L2 controls supported by the sensor
 */
const ControlInfoMap &CameraSensor::controls() const
{
	return subdev_->controls();
}

/**
 * \brief Read controls from the sensor
 * \param[in] ids The list of controls to read, specified by their ID
 *
 * This method reads the value of all controls contained in \a ids, and returns
 * their values as a ControlList.
 *
 * If any control in \a ids is not supported by the device, is disabled (i.e.
 * has the V4L2_CTRL_FLAG_DISABLED flag set), or if any other error occurs
 * during validation of the requested controls, no control is read and this
 * method returns an empty control list.
 *
 * \sa V4L2Device::getControls()
 *
 * \return The control values in a ControlList on success, or an empty list on
 * error
 */
ControlList CameraSensor::getControls(const std::vector<uint32_t> &ids)
{
	return subdev_->getControls(ids);
}

/**
 * \fn CameraSensor::properties()
 * \brief Retrieve the camera sensor properties
 * \return The list of camera sensor properties
 */

/**
 * \brief Write controls to the sensor
 * \param[in] ctrls The list of controls to write
 *
 * This method writes the value of all controls contained in \a ctrls, and
 * stores the values actually applied to the device in the corresponding
 * \a ctrls entry.
 *
 * If any control in \a ctrls is not supported by the device, is disabled (i.e.
 * has the V4L2_CTRL_FLAG_DISABLED flag set), is read-only, or if any other
 * error occurs during validation of the requested controls, no control is
 * written and this method returns -EINVAL.
 *
 * If an error occurs while writing the controls, the index of the first
 * control that couldn't be written is returned. All controls below that index
 * are written and their values are updated in \a ctrls, while all other
 * controls are not written and their values are not changed.
 *
 * \sa V4L2Device::setControls()
 *
 * \return 0 on success or an error code otherwise
 * \retval -EINVAL One of the control is not supported or not accessible
 * \retval i The index of the control that failed
 */
int CameraSensor::setControls(ControlList *ctrls)
{
	return subdev_->setControls(ctrls);
}

/**
 * \brief Assemble and return the camera sensor info
 * \param[out] info The camera sensor info
 *
 * The CameraSensorInfo content is assembled by inspecting the currently
 * applied sensor configuration and the sensor static properties.
 *
 * \return 0 on success, a negative error code otherwise
 */
int CameraSensor::sensorInfo(CameraSensorInfo *info) const
{
	info->model = model();

	/* Get the active area size. */
	Rectangle rect = {};
	int ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_DEFAULT, &rect);
	if (ret) {
		LOG(CameraSensor, Error)
			<< "Failed to construct camera sensor info: "
			<< "the camera sensor does not report the active area";

		return ret;
	}
	info->activeAreaSize = { rect.width, rect.height };

	/* It's mandatory for the subdevice to report its crop rectangle. */
	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP, &info->analogCrop);
	if (ret) {
		LOG(CameraSensor, Error)
			<< "Failed to construct camera sensor info: "
			<< "the camera sensor does not report the crop rectangle";
		return ret;
	}

	/* The bit depth and image size depend on the currently applied format. */
	V4L2SubdeviceFormat format{};
	ret = subdev_->getFormat(pad_, &format);
	if (ret)
		return ret;
	info->bitsPerPixel = format.bitsPerPixel();
	info->outputSize = format.size;

	/*
	 * Retrieve the pixel rate and the line length through V4L2 controls.
	 * Support for the V4L2_CID_PIXEL_RATE and V4L2_CID_HBLANK controls is
	 * mandatory.
	 */
	ControlList ctrls = subdev_->getControls({ V4L2_CID_PIXEL_RATE,
						   V4L2_CID_HBLANK });
	if (ctrls.empty()) {
		LOG(CameraSensor, Error)
			<< "Failed to retrieve camera info controls";
		return -EINVAL;
	}

	int32_t hblank = ctrls.get(V4L2_CID_HBLANK).get<int32_t>();
	info->lineLength = info->outputSize.width + hblank;
	info->pixelRate = ctrls.get(V4L2_CID_PIXEL_RATE).get<int64_t>();

	return 0;
}

std::string CameraSensor::logPrefix() const
{
	return "'" + entity_->name() + "'";
}

} /* namespace libcamera */