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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* v4l2_device.cpp - V4L2 Device
*/
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#include "log.h"
#include "v4l2_device.h"
/**
* \file v4l2_device.h
* \brief V4L2 Device API
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(V4L2)
/**
* \struct V4L2Capability
* \brief struct v4l2_capability object wrapper and helpers
*
* The V4L2Capability structure manages the information returned by the
* VIDIOC_QUERYCAP ioctl.
*/
/**
* \fn const char *V4L2Capability::driver()
* \brief Retrieve the driver module name
* \return The string containing the name of the driver module
*/
/**
* \fn const char *V4L2Capability::card()
* \brief Retrieve the device card name
* \return The string containing the device name
*/
/**
* \fn const char *V4L2Capability::bus_info()
* \brief Retrieve the location of the device in the system
* \return The string containing the device location
*/
/**
* \fn bool V4L2Capability::isCapture()
* \brief Identify if the device is capable of capturing video
* \return True if the device can capture video frames
*/
/**
* \fn bool V4L2Capability::isOutput()
* \brief Identify if the device is capable of outputting video
* \return True if the device can output video frames
*/
/**
* \fn bool V4L2Capability::hasStreaming()
* \brief Determine if the device can perform Streaming I/O
* \return True if the device provides Streaming I/O IOCTLs
*/
/**
* \class V4L2Device
* \brief V4L2Device object and API
*
* The V4L2 Device API class models an instance of a V4L2 device node.
* It is constructed with the path to a V4L2 video device node. The device node
* is only opened upon a call to open() which must be checked for success.
*
* The device capabilities are validated when the device is opened and the
* device is rejected if it is not a suitable V4L2 capture or output device, or
* if the device does not support streaming I/O.
*
* No API call other than open(), isOpen() and close() shall be called on an
* unopened device instance.
*
* Upon destruction any device left open will be closed, and any resources
* released.
*/
/**
* \brief Construct a V4L2Device
* \param devnode The file-system path to the video device node
*/
V4L2Device::V4L2Device(const std::string &devnode)
: devnode_(devnode), fd_(-1)
{
}
V4L2Device::~V4L2Device()
{
close();
}
/**
* \brief Open a V4L2 device and query its capabilities
* \return 0 on success, or a negative error code otherwise
*/
int V4L2Device::open()
{
int ret;
if (isOpen()) {
LOG(V4L2, Error) << "Device already open";
return -EBUSY;
}
ret = ::open(devnode_.c_str(), O_RDWR);
if (ret < 0) {
ret = -errno;
LOG(V4L2, Error)
<< "Failed to open V4L2 device '" << devnode_
<< "': " << strerror(-ret);
return ret;
}
fd_ = ret;
ret = ioctl(fd_, VIDIOC_QUERYCAP, &caps_);
if (ret < 0) {
ret = -errno;
LOG(V4L2, Error)
<< "Failed to query device capabilities: "
<< strerror(-ret);
return ret;
}
LOG(V4L2, Debug)
<< "Opened '" << devnode_ << "' "
<< caps_.bus_info() << ": " << caps_.driver()
<< ": " << caps_.card();
if (!caps_.isCapture() && !caps_.isOutput()) {
LOG(V4L2, Debug) << "Device is not a supported type";
return -EINVAL;
}
if (!caps_.hasStreaming()) {
LOG(V4L2, Error) << "Device does not support streaming I/O";
return -EINVAL;
}
return 0;
}
/**
* \brief Check if device is successfully opened
* \return True if the device is open, false otherwise
*/
bool V4L2Device::isOpen() const
{
return fd_ != -1;
}
/**
* \brief Close the device, releasing any resources acquired by open()
*/
void V4L2Device::close()
{
if (fd_ < 0)
return;
::close(fd_);
fd_ = -1;
}
/**
* \fn const char *V4L2Device::driverName()
* \brief Retrieve the name of the V4L2 device driver
* \return The string containing the driver name
*/
/**
* \fn const char *V4L2Device::deviceName()
* \brief Retrieve the name of the V4L2 device
* \return The string containing the device name
*/
/**
* \fn const char *V4L2Device::busName()
* \brief Retrieve the location of the device in the system
* \return The string containing the device location
*/
} /* namespace libcamera */
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