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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2018, Google Inc.
*
* media_device.cpp - Media device handler
*/
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string>
#include <vector>
#include <linux/media.h>
#include "log.h"
#include "media_device.h"
/**
* \file media_device.h
* \brief Provide a representation of a Linux kernel Media Controller device
* that exposes the full graph topology.
*/
namespace libcamera {
/**
* \class MediaDevice
* \brief The MediaDevice represents a Media Controller device with its full
* graph of connected objects.
*
* A MediaDevice instance is associated with a media controller device node when
* created, and that association is kept for the lifetime of the MediaDevice
* instance.
*
* The instance is created with an empty media graph. Before performing any
* other operation, it must be opened with the open() function and the media
* graph populated by calling populate(). Instances of MediaEntity, MediaPad and
* MediaLink are created to model the media graph, and stored in a map indexed
* by object id.
*
* The graph is valid once successfully populated, as reported by the valid()
* function. It can be queried to list all entities(), or entities can be
* looked up by name with getEntityByName(). The graph can be traversed from
* entity to entity through pads and links as exposed by the corresponding
* classes.
*
* An open media device will keep an open file handle for the underlying media
* controller device node. It can be closed at any time with a call to close().
* This will not invalidate the media graph and all cached media objects remain
* valid and can be accessed normally. The device can then be later reopened if
* needed to perform other operations that interact with the device node.
*/
/**
* \brief Construct a MediaDevice
* \param devnode The media device node path
*
* Once constructed the media device is invalid, and must be opened and
* populated with open() and populate() before the media graph can be queried.
*/
MediaDevice::MediaDevice(const std::string &devnode)
: devnode_(devnode), fd_(-1), valid_(false)
{
}
MediaDevice::~MediaDevice()
{
if (fd_ != -1)
::close(fd_);
clear();
}
/**
* \brief Open a media device and retrieve device information
*
* Before populating the media graph or performing any operation that interact
* with the device node associated with the media device, the device node must
* be opened.
*
* This function also retrieves media device information from the device node,
* which can be queried through driver().
*
* If the device is already open the function returns -EBUSY.
*
* \return 0 on success or a negative error code otherwise
*/
int MediaDevice::open()
{
if (fd_ != -1) {
LOG(Error) << "MediaDevice already open";
return -EBUSY;
}
int ret = ::open(devnode_.c_str(), O_RDWR);
if (ret < 0) {
ret = -errno;
LOG(Error) << "Failed to open media device at " << devnode_
<< ": " << strerror(-ret);
return ret;
}
fd_ = ret;
struct media_device_info info = { };
ret = ioctl(fd_, MEDIA_IOC_DEVICE_INFO, &info);
if (ret) {
ret = -errno;
LOG(Error) << "Failed to get media device info "
<< ": " << strerror(-ret);
return ret;
}
driver_ = info.driver;
return 0;
}
/**
* \brief Close the media device
*
* This function closes the media device node. It does not invalidate the media
* graph and all cached media objects remain valid and can be accessed normally.
* Once closed no operation interacting with the media device node can be
* performed until the device is opened again.
*
* Closing an already closed device is allowed and will not perform any
* operation.
*
* \sa open()
*/
void MediaDevice::close()
{
if (fd_ == -1)
return;
::close(fd_);
fd_ = -1;
}
/**
* \brief Populate the media graph with media objects
*
* This function enumerates all media objects in the media device graph and
* creates their MediaObject representations. All entities, pads and links are
* stored as MediaEntity, MediaPad and MediaLink respectively, with cross-
* references between objects. Interfaces are not processed.
*
* Entities are stored in a separate list in the MediaDevice to ease lookup,
* while pads are accessible from the entity they belong to and links from the
* pads they connect.
*
* \return 0 on success, a negative error code otherwise
*/
int MediaDevice::populate()
{
struct media_v2_topology topology = { };
struct media_v2_entity *ents = nullptr;
struct media_v2_link *links = nullptr;
struct media_v2_pad *pads = nullptr;
__u64 version = -1;
int ret;
clear();
/*
* Keep calling G_TOPOLOGY until the version number stays stable.
*/
while (true) {
topology.topology_version = 0;
topology.ptr_entities = reinterpret_cast<__u64>(ents);
topology.ptr_links = reinterpret_cast<__u64>(links);
topology.ptr_pads = reinterpret_cast<__u64>(pads);
ret = ioctl(fd_, MEDIA_IOC_G_TOPOLOGY, &topology);
if (ret < 0) {
ret = -errno;
LOG(Error) << "Failed to enumerate topology: "
<< strerror(-ret);
return ret;
}
if (version == topology.topology_version)
break;
delete[] links;
delete[] ents;
delete[] pads;
ents = new media_v2_entity[topology.num_entities];
links = new media_v2_link[topology.num_links];
pads = new media_v2_pad[topology.num_pads];
version = topology.topology_version;
}
/* Populate entities, pads and links. */
if (populateEntities(topology) &&
populatePads(topology) &&
populateLinks(topology))
valid_ = true;
delete[] links;
delete[] ents;
delete[] pads;
if (!valid_) {
clear();
return -EINVAL;
}
return 0;
}
/**
* \fn MediaDevice::valid()
* \brief Query whether the media graph is valid
* \return true if the media graph is valid, false otherwise
*/
/**
* \fn MediaDevice::driver()
* \brief Retrieve the media device driver name
* \return The name of the kernel driver that handles the MediaDevice
*/
/**
* \fn MediaDevice::devnode()
* \brief Retrieve the media device device node path
* \return The MediaDevice devnode path
*/
/**
* \fn MediaDevice::entities()
* \brief Retrieve the list of entities in the media graph
* \return The list of MediaEntities registered in the MediaDevice
*/
/**
* \brief Return the MediaEntity with name \a name
* \param name The entity name
* \return The entity with \a name
* \return nullptr if no entity with \a name is found
*/
MediaEntity *MediaDevice::getEntityByName(const std::string &name)
{
for (MediaEntity *e : entities_)
if (e->name() == name)
return e;
return nullptr;
}
/**
* \var MediaDevice::objects_
* \brief Global map of media objects (entities, pads, links) keyed by their
* object id.
*/
/**
* \brief Retrieve the media graph object specified by \a id
* \return The graph object, or nullptr if no object with \a id is found
*/
MediaObject *MediaDevice::object(unsigned int id)
{
auto it = objects_.find(id);
return (it == objects_.end()) ? nullptr : it->second;
}
/**
* \brief Add a media object to the media graph
*
* If the \a object has a unique id it is added to the media graph, and its
* lifetime will be managed by the media device. Otherwise the object isn't
* added to the graph and the caller must delete it.
*
* \return true if the object was successfully added to the graph and false
* otherwise
*/
bool MediaDevice::addObject(MediaObject *object)
{
if (objects_.find(object->id()) != objects_.end()) {
LOG(Error) << "Element with id " << object->id()
<< " already enumerated.";
return false;
}
objects_[object->id()] = object;
return true;
}
/**
* \brief Delete all graph objects in the media device
*
* Clear the media graph and delete all the objects it contains. After this
* function returns any previously obtained pointer to a media graph object
* becomes invalid.
*
* The media device graph state is reset to invalid when the graph is cleared.
*
* \sa valid()
*/
void MediaDevice::clear()
{
for (auto const &o : objects_)
delete o.second;
objects_.clear();
entities_.clear();
valid_ = false;
}
/**
* \var MediaDevice::entities_
* \brief Global list of media entities in the media graph
*/
/*
* For each entity in the media graph create a MediaEntity and store a
* reference in the media device objects map and entities list.
*/
bool MediaDevice::populateEntities(const struct media_v2_topology &topology)
{
media_v2_entity *mediaEntities = reinterpret_cast<media_v2_entity *>
(topology.ptr_entities);
for (unsigned int i = 0; i < topology.num_entities; ++i) {
MediaEntity *entity = new MediaEntity(&mediaEntities[i]);
if (!addObject(entity)) {
delete entity;
return false;
}
entities_.push_back(entity);
}
return true;
}
bool MediaDevice::populatePads(const struct media_v2_topology &topology)
{
media_v2_pad *mediaPads = reinterpret_cast<media_v2_pad *>
(topology.ptr_pads);
for (unsigned int i = 0; i < topology.num_pads; ++i) {
unsigned int entity_id = mediaPads[i].entity_id;
/* Store a reference to this MediaPad in entity. */
MediaEntity *mediaEntity = dynamic_cast<MediaEntity *>
(object(entity_id));
if (!mediaEntity) {
LOG(Error) << "Failed to find entity with id: "
<< entity_id;
return false;
}
MediaPad *pad = new MediaPad(&mediaPads[i], mediaEntity);
if (!addObject(pad)) {
delete pad;
return false;
}
mediaEntity->addPad(pad);
}
return true;
}
bool MediaDevice::populateLinks(const struct media_v2_topology &topology)
{
media_v2_link *mediaLinks = reinterpret_cast<media_v2_link *>
(topology.ptr_links);
for (unsigned int i = 0; i < topology.num_links; ++i) {
/*
* Skip links between entities and interfaces: we only care
* about pad-2-pad links here.
*/
if ((mediaLinks[i].flags & MEDIA_LNK_FL_LINK_TYPE) ==
MEDIA_LNK_FL_INTERFACE_LINK)
continue;
/* Store references to source and sink pads in the link. */
unsigned int source_id = mediaLinks[i].source_id;
MediaPad *source = dynamic_cast<MediaPad *>
(object(source_id));
if (!source) {
LOG(Error) << "Failed to find pad with id: "
<< source_id;
return false;
}
unsigned int sink_id = mediaLinks[i].sink_id;
MediaPad *sink = dynamic_cast<MediaPad *>
(object(sink_id));
if (!sink) {
LOG(Error) << "Failed to find pad with id: "
<< sink_id;
return false;
}
MediaLink *link = new MediaLink(&mediaLinks[i], source, sink);
if (!addObject(link)) {
delete link;
return false;
}
source->addLink(link);
sink->addLink(link);
}
return true;
}
} /* namespace libcamera */
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