[libcamera-devel,v2,3/4] libcamera: camera_lens: Add a new class to model a camera lens

14417 diff mbox series

The CameraLens class abstracts camera lens and provides helper
functions to ease interactions with them.

Signed-off-by: Han-Lin Chen <hanlinchen@chromium.org>
---
 Documentation/index.rst                    |   1 +
 Documentation/lens_driver_requirements.rst |  28 +++
 Documentation/meson.build                  |   1 +
 include/libcamera/internal/camera_lens.h   |  60 +++++
 src/libcamera/camera_lens.cpp              | 261 +++++++++++++++++++++
 src/libcamera/meson.build                  |   1 +
 6 files changed, 352 insertions(+)
 create mode 100644 Documentation/lens_driver_requirements.rst
 create mode 100644 include/libcamera/internal/camera_lens.h
 create mode 100644 src/libcamera/camera_lens.cpp

Hi Han-Lin,

On 29/10/2021 13:59, Han-Lin Chen wrote:
> The CameraLens class abstracts camera lens and provides helper
> functions to ease interactions with them.
> 
> Signed-off-by: Han-Lin Chen <hanlinchen@chromium.org>
> ---
>   Documentation/index.rst                    |   1 +
>   Documentation/lens_driver_requirements.rst |  28 +++
>   Documentation/meson.build                  |   1 +
>   include/libcamera/internal/camera_lens.h   |  60 +++++
>   src/libcamera/camera_lens.cpp              | 261 +++++++++++++++++++++
>   src/libcamera/meson.build                  |   1 +
>   6 files changed, 352 insertions(+)
>   create mode 100644 Documentation/lens_driver_requirements.rst
>   create mode 100644 include/libcamera/internal/camera_lens.h
>   create mode 100644 src/libcamera/camera_lens.cpp
> 
> diff --git a/Documentation/index.rst b/Documentation/index.rst
> index 1f4fc485..0ee10044 100644
> --- a/Documentation/index.rst
> +++ b/Documentation/index.rst
> @@ -21,3 +21,4 @@
>      Tracing guide <guides/tracing>
>      Environment variables <environment_variables>
>      Sensor driver requirements <sensor_driver_requirements>
> +   Lens driver requirements <lens_driver_requirements>
> diff --git a/Documentation/lens_driver_requirements.rst b/Documentation/lens_driver_requirements.rst
> new file mode 100644
> index 00000000..afc300cf
> --- /dev/null
> +++ b/Documentation/lens_driver_requirements.rst
> @@ -0,0 +1,28 @@
> +.. SPDX-License-Identifier: CC-BY-SA-4.0
> +
> +.. _lens-driver-requirements:
> +
> +Lens Driver Requirements
> +========================
> +
> +libcamera handles lens devices in the CameraLens class and defines
> +a consistent interface through its API towards other library components.
> +
> +The CameraLens class uses the V4L2 subdev kernel API to interface with the
> +camera lens through one or multiple sub-devices exposed in userspace by
> +the lens driver.
> +
> +In order for libcamera to be fully operational and provide all the required
> +information to interface with the camera lens to applications and pipeline
> +handlers, a set of mandatory features the driver has to support has been defined.
> +
> +Mandatory Requirements
> +----------------------
> +
> +The lens driver is assumed to be fully compliant with the V4L2 specification.
> +
> +The lens driver shall support the following V4L2 controls:
> +
> +* `V4L2_CID_FOCUS_ABSOLUTE`_
> +
> +.. _V4L2_CID_FOCUS_ABSOLUTE: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-camera.html
> diff --git a/Documentation/meson.build b/Documentation/meson.build
> index df36a808..6a1ef164 100644
> --- a/Documentation/meson.build
> +++ b/Documentation/meson.build
> @@ -61,6 +61,7 @@ if sphinx.found()
>           'guides/pipeline-handler.rst',
>           'guides/tracing.rst',
>           'index.rst',
> +        'lens_driver_requirements.rst',
>           'sensor_driver_requirements.rst',
>          '../README.rst',
>       ]
> diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> new file mode 100644
> index 00000000..c558ea4f
> --- /dev/null
> +++ b/include/libcamera/internal/camera_lens.h
> @@ -0,0 +1,60 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * camera_lens.h - A camera lens
> + */
> +#ifndef __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> +#define __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> +
> +#include <libcamera/base/class.h>
> +#include <libcamera/base/log.h>
> +
> +#include <libcamera/controls.h>
> +#include "libcamera/internal/v4l2_subdevice.h"
> +
> +namespace libcamera {
> +
> +class MediaEntity;
> +
> +class CameraLens : protected Loggable
> +{
> +public:
> +	explicit CameraLens(const MediaEntity *entity);
> +	~CameraLens();
> +
> +	int init();
> +
> +	const std::string &model() const { return model_; }
> +	const MediaEntity *entity() const { return entity_; }
> +
> +	const ControlInfoMap &controls() const;
> +	ControlList getControls(const std::vector<uint32_t> &ids);
> +	int setControls(ControlList *ctrls);
> +
> +	V4L2Subdevice *device() { return subdev_.get(); }
> +
> +	const ControlList &properties() const { return properties_; }
> +
> +protected:
> +	std::string logPrefix() const override;
> +
> +private:
> +	LIBCAMERA_DISABLE_COPY(CameraLens)
> +
> +	int generateId();
> +	int validateLensDriver();
> +	int initProperties();
> +
> +	const MediaEntity *entity_;
> +	std::unique_ptr<V4L2Subdevice> subdev_;
> +
> +	std::string model_;
> +	std::string id_;
> +
> +	ControlList properties_;
> +};
> +
> +} /* namespace libcamera */
> +
> +#endif /* __LIBCAMERA_INTERNAL_CAMERA_LENS_H__ */
> diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> new file mode 100644
> index 00000000..8529737c
> --- /dev/null
> +++ b/src/libcamera/camera_lens.cpp
> @@ -0,0 +1,261 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2021, Google Inc.
> + *
> + * camera_lens.cpp - A camera lens
> + */
> +
> +#include "libcamera/internal/camera_lens.h"
> +#include "libcamera/internal/media_device.h"
> +
> +#include <regex>
> +
> +#include <libcamera/property_ids.h>
> +
> +#include "libcamera/internal/sysfs.h"
> +
> +/**
> + * \file camera_lens.h
> + * \brief A camera lens
> + */
> +
> +namespace libcamera {
> +
> +LOG_DEFINE_CATEGORY(CameraLens)
> +
> +/**
> + * \class CameraLens
> + * \brief A camera lens based on V4L2 subdevices
> + *
> + * The CameraLens class eases handling of lens for pipeline handlers by
> + * hiding the details of the V4L2 subdevice kernel API and caching lens
> + * information.
> + *
> + * The implementation is currently limited to lens that expose a single V4L2
> + * subdevice. It will be extended to support more complex devices as the needs
> + * arise.
> + */
> +
> +/**
> + * \brief Construct a CameraLens
> + * \param[in] entity The media entity backing the camera lens
> + *
> + * Once constructed the instance must be initialized with init().
> + */
> +CameraLens::CameraLens(const MediaEntity *entity)
> +	: entity_(entity),
> +	  properties_(properties::properties)
> +{
> +}
> +
> +/**
> + * \brief Destroy a CameraLens
> + */
> +CameraLens::~CameraLens()
> +{
> +}
> +

If it's empty you may make it a default in the class definition ?

> +/**
> + * \brief Initialize the camera lens instance
> + *
> + * This function performs the initialisation steps of the CameraLens 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 CameraLens::init()
> +{
> +	if (entity_->function() != MEDIA_ENT_F_LENS) {
> +		LOG(CameraLens, Error)
> +			<< "Invalid lens function "
> +			<< utils::hex(entity_->function());
> +		return -EINVAL;
> +	}
> +
> +	/* Create and open the subdev. */
> +	subdev_ = std::make_unique<V4L2Subdevice>(entity_);
> +	int ret = subdev_->open();
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = validateLensDriver();
> +	if (ret)
> +		return ret;
> +
> +	ret = initProperties();
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +int CameraLens::validateLensDriver()
> +{
> +	int err = 0;
> +	static constexpr uint32_t mandatoryControls[] = {
> +		V4L2_CID_FOCUS_ABSOLUTE
> +	};
> +
> +	const ControlInfoMap &controls = subdev_->controls();
> +	for (uint32_t ctrl : mandatoryControls) {
> +		if (!controls.count(ctrl)) {
> +			LOG(CameraLens, Error)
> +				<< "Mandatory V4L2 control " << utils::hex(ctrl)
> +				<< " not available";
> +			err = -EINVAL;
> +		}
> +	}
> +
> +	if (err) {
> +		LOG(CameraLens, Error)
> +			<< "The lens kernel driver needs to be fixed";
> +		LOG(CameraLens, Error)
> +			<< "See Documentation/lens_driver_requirements.rst in

You missed a " at the end of the line it does not compile.

> +			<< " the libcamera sources for more information";
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +int CameraLens::initProperties()
> +{
> +	/*
> +	 * Extract the camera lens model name from the media entity name.
> +	 *
> +	 * There is no standardized naming scheme for lens entities in the
> +	 * Linux kernel at the moment.
> +	 *
> +	 * - The most common rule, used by I2C lens, associates the model
> +	 *   name with the I2C bus number and address (e.g. 'dw9714 8-000c').
> +	 *
> +	 * 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;
> +
> +	properties_.set(properties::Model, utils::toAscii(model_));
> +
> +	return 0;
> +}
> +
> +/**
> + * \fn CameraLens::model()
> + * \brief Retrieve the lens model name
> + *
> + * The lens model name is a free-formed string that uniquely identifies the
> + * lens model.
> + *
> + * \return The lens model name
> + */
> +
> +/**
> + * \fn CameraLens::id()
> + * \brief Retrieve the lens ID
> + *
> + * The lens ID is a free-form string that uniquely identifies the lens in
> + * the system.
> + *
> + * \return The lens ID
> + */
> +
> +/**
> + * \fn CameraLens::entity()
> + * \brief Retrieve the lens media entity
> + * \return The lens media entity
> + */
> +
> +/**
> + * \brief Retrieve the supported V4L2 controls and their information
> + *
> + * Control information is updated automatically to reflect the current lens
> + * configuration when the setFormat() function is called, without invalidating
> + * any iterator on the ControlInfoMap.
> + *
> + * \return A map of the V4L2 controls supported by the lens
> + */
> +const ControlInfoMap &CameraLens::controls() const
> +{
> +	return subdev_->controls();
> +}
> +
> +/**
> + * \brief Read V4L2 controls from the lens
> + * \param[in] ids The list of controls to read, specified by their ID
> + *
> + * This function reads the value of all controls contained in \a ids, and
> + * returns their values as a ControlList. The control identifiers are defined by
> + * the V4L2 specification (V4L2_CID_*).
> + *
> + * 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
> + * function returns an empty control list.
> + *
> + * \sa V4L2Device::getControls()
> + *
> + * \return The control values in a ControlList on success, or an empty list on
> + * error
> + */
> +ControlList CameraLens::getControls(const std::vector<uint32_t> &ids)
> +{
> +	return subdev_->getControls(ids);
> +}
> +
> +/**
> + * \brief Write V4L2 controls to the lens
> + * \param[in] ctrls The list of controls to write
> + *
> + * This function 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. The control identifiers are defined by the V4L2 specification
> + * (V4L2_CID_*).
> + *
> + * 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 function 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 CameraLens::setControls(ControlList *ctrls)
> +{
> +	return subdev_->setControls(ctrls);
> +}
> +
> +/**
> + * \fn CameraLens::device()
> + * \brief Retrieve the camera lens device
> + * \todo Remove this function by integrating DelayedControl with CameraLens
> + * \return The camera lens device
> + */
> +
> +/**
> + * \fn CameraLens::properties()
> + * \brief Retrieve the camera lens properties
> + * \return The list of camera lens properties
> + */
> +
> +std::string CameraLens::logPrefix() const
> +{
> +	return "'" + entity_->name() + "'";
> +}
> +
> +} /* namespace libcamera */
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 6727a777..3bee8fee 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -5,6 +5,7 @@ libcamera_sources = files([
>       'byte_stream_buffer.cpp',
>       'camera.cpp',
>       'camera_controls.cpp',
> +    'camera_lens.cpp',
>       'camera_manager.cpp',
>       'camera_sensor.cpp',
>       'camera_sensor_properties.cpp',
>

Hi Jean-Michel,

On Thu, Nov 4, 2021 at 7:49 PM Jean-Michel Hautbois
<jeanmichel.hautbois@ideasonboard.com> wrote:
>
> Hi Han-Lin,
>
> On 29/10/2021 13:59, Han-Lin Chen wrote:
> > The CameraLens class abstracts camera lens and provides helper
> > functions to ease interactions with them.
> >
> > Signed-off-by: Han-Lin Chen <hanlinchen@chromium.org>
> > ---
> >   Documentation/index.rst                    |   1 +
> >   Documentation/lens_driver_requirements.rst |  28 +++
> >   Documentation/meson.build                  |   1 +
> >   include/libcamera/internal/camera_lens.h   |  60 +++++
> >   src/libcamera/camera_lens.cpp              | 261 +++++++++++++++++++++
> >   src/libcamera/meson.build                  |   1 +
> >   6 files changed, 352 insertions(+)
> >   create mode 100644 Documentation/lens_driver_requirements.rst
> >   create mode 100644 include/libcamera/internal/camera_lens.h
> >   create mode 100644 src/libcamera/camera_lens.cpp
> >
> > diff --git a/Documentation/index.rst b/Documentation/index.rst
> > index 1f4fc485..0ee10044 100644
> > --- a/Documentation/index.rst
> > +++ b/Documentation/index.rst
> > @@ -21,3 +21,4 @@
> >      Tracing guide <guides/tracing>
> >      Environment variables <environment_variables>
> >      Sensor driver requirements <sensor_driver_requirements>
> > +   Lens driver requirements <lens_driver_requirements>
> > diff --git a/Documentation/lens_driver_requirements.rst b/Documentation/lens_driver_requirements.rst
> > new file mode 100644
> > index 00000000..afc300cf
> > --- /dev/null
> > +++ b/Documentation/lens_driver_requirements.rst
> > @@ -0,0 +1,28 @@
> > +.. SPDX-License-Identifier: CC-BY-SA-4.0
> > +
> > +.. _lens-driver-requirements:
> > +
> > +Lens Driver Requirements
> > +========================
> > +
> > +libcamera handles lens devices in the CameraLens class and defines
> > +a consistent interface through its API towards other library components.
> > +
> > +The CameraLens class uses the V4L2 subdev kernel API to interface with the
> > +camera lens through one or multiple sub-devices exposed in userspace by
> > +the lens driver.
> > +
> > +In order for libcamera to be fully operational and provide all the required
> > +information to interface with the camera lens to applications and pipeline
> > +handlers, a set of mandatory features the driver has to support has been defined.
> > +
> > +Mandatory Requirements
> > +----------------------
> > +
> > +The lens driver is assumed to be fully compliant with the V4L2 specification.
> > +
> > +The lens driver shall support the following V4L2 controls:
> > +
> > +* `V4L2_CID_FOCUS_ABSOLUTE`_
> > +
> > +.. _V4L2_CID_FOCUS_ABSOLUTE: https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/ext-ctrls-camera.html
> > diff --git a/Documentation/meson.build b/Documentation/meson.build
> > index df36a808..6a1ef164 100644
> > --- a/Documentation/meson.build
> > +++ b/Documentation/meson.build
> > @@ -61,6 +61,7 @@ if sphinx.found()
> >           'guides/pipeline-handler.rst',
> >           'guides/tracing.rst',
> >           'index.rst',
> > +        'lens_driver_requirements.rst',
> >           'sensor_driver_requirements.rst',
> >          '../README.rst',
> >       ]
> > diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> > new file mode 100644
> > index 00000000..c558ea4f
> > --- /dev/null
> > +++ b/include/libcamera/internal/camera_lens.h
> > @@ -0,0 +1,60 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2021, Google Inc.
> > + *
> > + * camera_lens.h - A camera lens
> > + */
> > +#ifndef __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> > +#define __LIBCAMERA_INTERNAL_CAMERA_LENS_H__
> > +
> > +#include <libcamera/base/class.h>
> > +#include <libcamera/base/log.h>
> > +
> > +#include <libcamera/controls.h>
> > +#include "libcamera/internal/v4l2_subdevice.h"
> > +
> > +namespace libcamera {
> > +
> > +class MediaEntity;
> > +
> > +class CameraLens : protected Loggable
> > +{
> > +public:
> > +     explicit CameraLens(const MediaEntity *entity);
> > +     ~CameraLens();
> > +
> > +     int init();
> > +
> > +     const std::string &model() const { return model_; }
> > +     const MediaEntity *entity() const { return entity_; }
> > +
> > +     const ControlInfoMap &controls() const;
> > +     ControlList getControls(const std::vector<uint32_t> &ids);
> > +     int setControls(ControlList *ctrls);
> > +
> > +     V4L2Subdevice *device() { return subdev_.get(); }
> > +
> > +     const ControlList &properties() const { return properties_; }
> > +
> > +protected:
> > +     std::string logPrefix() const override;
> > +
> > +private:
> > +     LIBCAMERA_DISABLE_COPY(CameraLens)
> > +
> > +     int generateId();
> > +     int validateLensDriver();
> > +     int initProperties();
> > +
> > +     const MediaEntity *entity_;
> > +     std::unique_ptr<V4L2Subdevice> subdev_;
> > +
> > +     std::string model_;
> > +     std::string id_;
> > +
> > +     ControlList properties_;
> > +};
> > +
> > +} /* namespace libcamera */
> > +
> > +#endif /* __LIBCAMERA_INTERNAL_CAMERA_LENS_H__ */
> > diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> > new file mode 100644
> > index 00000000..8529737c
> > --- /dev/null
> > +++ b/src/libcamera/camera_lens.cpp
> > @@ -0,0 +1,261 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2021, Google Inc.
> > + *
> > + * camera_lens.cpp - A camera lens
> > + */
> > +
> > +#include "libcamera/internal/camera_lens.h"
> > +#include "libcamera/internal/media_device.h"
> > +
> > +#include <regex>
> > +
> > +#include <libcamera/property_ids.h>
> > +
> > +#include "libcamera/internal/sysfs.h"
> > +
> > +/**
> > + * \file camera_lens.h
> > + * \brief A camera lens
> > + */
> > +
> > +namespace libcamera {
> > +
> > +LOG_DEFINE_CATEGORY(CameraLens)
> > +
> > +/**
> > + * \class CameraLens
> > + * \brief A camera lens based on V4L2 subdevices
> > + *
> > + * The CameraLens class eases handling of lens for pipeline handlers by
> > + * hiding the details of the V4L2 subdevice kernel API and caching lens
> > + * information.
> > + *
> > + * The implementation is currently limited to lens that expose a single V4L2
> > + * subdevice. It will be extended to support more complex devices as the needs
> > + * arise.
> > + */
> > +
> > +/**
> > + * \brief Construct a CameraLens
> > + * \param[in] entity The media entity backing the camera lens
> > + *
> > + * Once constructed the instance must be initialized with init().
> > + */
> > +CameraLens::CameraLens(const MediaEntity *entity)
> > +     : entity_(entity),
> > +       properties_(properties::properties)
> > +{
> > +}
> > +
> > +/**
> > + * \brief Destroy a CameraLens
> > + */
> > +CameraLens::~CameraLens()
> > +{
> > +}
> > +
>
> If it's empty you may make it a default in the class definition ?
SGTM.
>
> > +/**
> > + * \brief Initialize the camera lens instance
> > + *
> > + * This function performs the initialisation steps of the CameraLens 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 CameraLens::init()
> > +{
> > +     if (entity_->function() != MEDIA_ENT_F_LENS) {
> > +             LOG(CameraLens, Error)
> > +                     << "Invalid lens function "
> > +                     << utils::hex(entity_->function());
> > +             return -EINVAL;
> > +     }
> > +
> > +     /* Create and open the subdev. */
> > +     subdev_ = std::make_unique<V4L2Subdevice>(entity_);
> > +     int ret = subdev_->open();
> > +     if (ret < 0)
> > +             return ret;
> > +
> > +     ret = validateLensDriver();
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = initProperties();
> > +     if (ret)
> > +             return ret;
> > +
> > +     return 0;
> > +}
> > +
> > +int CameraLens::validateLensDriver()
> > +{
> > +     int err = 0;
> > +     static constexpr uint32_t mandatoryControls[] = {
> > +             V4L2_CID_FOCUS_ABSOLUTE
> > +     };
> > +
> > +     const ControlInfoMap &controls = subdev_->controls();
> > +     for (uint32_t ctrl : mandatoryControls) {
> > +             if (!controls.count(ctrl)) {
> > +                     LOG(CameraLens, Error)
> > +                             << "Mandatory V4L2 control " << utils::hex(ctrl)
> > +                             << " not available";
> > +                     err = -EINVAL;
> > +             }
> > +     }
> > +
> > +     if (err) {
> > +             LOG(CameraLens, Error)
> > +                     << "The lens kernel driver needs to be fixed";
> > +             LOG(CameraLens, Error)
> > +                     << "See Documentation/lens_driver_requirements.rst in
>
> You missed a " at the end of the line it does not compile.
>
Thanks! Not sure how I could miss that.
> > +                     << " the libcamera sources for more information";
> > +             return err;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +int CameraLens::initProperties()
> > +{
> > +     /*
> > +      * Extract the camera lens model name from the media entity name.
> > +      *
> > +      * There is no standardized naming scheme for lens entities in the
> > +      * Linux kernel at the moment.
> > +      *
> > +      * - The most common rule, used by I2C lens, associates the model
> > +      *   name with the I2C bus number and address (e.g. 'dw9714 8-000c').
> > +      *
> > +      * 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;
> > +
> > +     properties_.set(properties::Model, utils::toAscii(model_));
> > +
> > +     return 0;
> > +}
> > +
> > +/**
> > + * \fn CameraLens::model()
> > + * \brief Retrieve the lens model name
> > + *
> > + * The lens model name is a free-formed string that uniquely identifies the
> > + * lens model.
> > + *
> > + * \return The lens model name
> > + */
> > +
> > +/**
> > + * \fn CameraLens::id()
> > + * \brief Retrieve the lens ID
> > + *
> > + * The lens ID is a free-form string that uniquely identifies the lens in
> > + * the system.
> > + *
> > + * \return The lens ID
> > + */
> > +
> > +/**
> > + * \fn CameraLens::entity()
> > + * \brief Retrieve the lens media entity
> > + * \return The lens media entity
> > + */
> > +
> > +/**
> > + * \brief Retrieve the supported V4L2 controls and their information
> > + *
> > + * Control information is updated automatically to reflect the current lens
> > + * configuration when the setFormat() function is called, without invalidating
> > + * any iterator on the ControlInfoMap.
> > + *
> > + * \return A map of the V4L2 controls supported by the lens
> > + */
> > +const ControlInfoMap &CameraLens::controls() const
> > +{
> > +     return subdev_->controls();
> > +}
> > +
> > +/**
> > + * \brief Read V4L2 controls from the lens
> > + * \param[in] ids The list of controls to read, specified by their ID
> > + *
> > + * This function reads the value of all controls contained in \a ids, and
> > + * returns their values as a ControlList. The control identifiers are defined by
> > + * the V4L2 specification (V4L2_CID_*).
> > + *
> > + * 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
> > + * function returns an empty control list.
> > + *
> > + * \sa V4L2Device::getControls()
> > + *
> > + * \return The control values in a ControlList on success, or an empty list on
> > + * error
> > + */
> > +ControlList CameraLens::getControls(const std::vector<uint32_t> &ids)
> > +{
> > +     return subdev_->getControls(ids);
> > +}
> > +
> > +/**
> > + * \brief Write V4L2 controls to the lens
> > + * \param[in] ctrls The list of controls to write
> > + *
> > + * This function 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. The control identifiers are defined by the V4L2 specification
> > + * (V4L2_CID_*).
> > + *
> > + * 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 function 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 CameraLens::setControls(ControlList *ctrls)
> > +{
> > +     return subdev_->setControls(ctrls);
> > +}
> > +
> > +/**
> > + * \fn CameraLens::device()
> > + * \brief Retrieve the camera lens device
> > + * \todo Remove this function by integrating DelayedControl with CameraLens
> > + * \return The camera lens device
> > + */
> > +
> > +/**
> > + * \fn CameraLens::properties()
> > + * \brief Retrieve the camera lens properties
> > + * \return The list of camera lens properties
> > + */
> > +
> > +std::string CameraLens::logPrefix() const
> > +{
> > +     return "'" + entity_->name() + "'";
> > +}
> > +
> > +} /* namespace libcamera */
> > diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> > index 6727a777..3bee8fee 100644
> > --- a/src/libcamera/meson.build
> > +++ b/src/libcamera/meson.build
> > @@ -5,6 +5,7 @@ libcamera_sources = files([
> >       'byte_stream_buffer.cpp',
> >       'camera.cpp',
> >       'camera_controls.cpp',
> > +    'camera_lens.cpp',
> >       'camera_manager.cpp',
> >       'camera_sensor.cpp',
> >       'camera_sensor_properties.cpp',
> >