libcamera/vivid.git - libcamera pipeline handler for VIVID

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/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Copyright (C) 2018, Google Inc. * * device_enumerator.cpp - Enumeration and matching */ #include "libcamera/internal/device_enumerator.h" #include <string.h> #include <libcamera/base/log.h> #include "libcamera/internal/device_enumerator_sysfs.h" #include "libcamera/internal/device_enumerator_udev.h" #include "libcamera/internal/media_device.h" /** * \file device_enumerator.h * \brief Enumeration and matching of media devices * * The purpose of device enumeration and matching is to find media devices in * the system and map them to pipeline handlers. * * At the core of the enumeration is the DeviceEnumerator class, responsible * for enumerating all media devices in the system. It handles all interactions * with the operating system in a platform-specific way. For each media device * found an instance of MediaDevice is created to store information about the * device gathered from the kernel through the Media Controller API. * * The DeviceEnumerator can enumerate all or specific media devices in the * system. When a new media device is added the enumerator creates a * corresponding MediaDevice instance. * * The enumerator supports searching among enumerated devices based on criteria * expressed in a DeviceMatch object. */ namespace libcamera { LOG_DEFINE_CATEGORY(DeviceEnumerator) /** * \class DeviceMatch * \brief Description of a media device search pattern * * The DeviceMatch class describes a media device using properties from the * Media Controller struct media_device_info, entity names in the media graph * or other properties that can be used to identify a media device. * * The description is meant to be filled by pipeline managers and passed to a * device enumerator to find matching media devices. * * A DeviceMatch is created with a specific Linux device driver in mind, * therefore the name of the driver is a required property. One or more Entity * names can be added as match criteria. * * Pipeline handlers are recommended to add entities to DeviceMatch as * appropriare to ensure that the media device they need can be uniquely * identified. This is useful when the corresponding kernel driver can produce * different graphs, for instance as a result of different driver versions or * hardware configurations, and not all those graphs are suitable for a pipeline * handler. */ /** * \brief Construct a media device search pattern * \param[in] driver The Linux device driver name that created the media device */ DeviceMatch::DeviceMatch(const std::string &driver) : driver_(driver) { } /** * \brief Add a media entity name to the search pattern * \param[in] entity The name of the entity in the media graph */ void DeviceMatch::add(const std::string &entity) { entities_.push_back(entity); } /** * \brief Compare a search pattern with a media device * \param[in] device The media device * * Matching is performed on the Linux device driver name and entity names from * the media graph. A match is found if both the driver name matches and the * media device contains all the entities listed in the search pattern. * * \return true if the media device matches the search pattern, false otherwise */ bool DeviceMatch::match(const MediaDevice *device) const { if (driver_ != device->driver()) return false; for (const std::string &name : entities_) { bool found = false; for (const MediaEntity *entity : device->entities()) { if (name == entity->name()) { if (!entity->deviceNode().empty()) { found = true; break; } else { LOG(DeviceEnumerator, Debug) << "Skip " << entity->name() << ": no device node"; } } } if (!found) return false; } return true; } /** * \class DeviceEnumerator * \brief Enumerate, store and search media devices * * The DeviceEnumerator class is responsible for all interactions with the * operating system related to media devices. It enumerates all media devices * in the system, and for each device found creates an instance of the * MediaDevice class and stores it internally. The list of media devices can * then be searched using DeviceMatch search patterns. * * The enumerator also associates media device entities with device node paths. */ /** * \brief Create a new device enumerator matching the systems capabilities * * Depending on how the operating system handles device detection, hot-plug * notification and device node lookup, different device enumerator * implementations may be needed. This function creates the best enumerator for * the operating system based on the available resources. Not all different


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