libcamera/vivid.git - libcamera pipeline handler for VIVID

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author	Kieran Bingham <kieran.bingham@ideasonboard.com>	2018-12-14 13:49:20 +0000
committer	Kieran Bingham <kieran.bingham@ideasonboard.com>	2019-01-17 21:55:21 +0000
commit	e74f3eebb498634f438a005b2ad5b7f1778091e8 (patch)
tree	fbfac530688d24ec3ab58c6ab27863d3d734824b /test/v4l2_device
parent	e399a0745b0c306757c8f7c38f5b2864d442db7e (diff)

libcamera: Add V4L2 Device object

Provide a helper V4L2 device object capable of interacting with the V4L2 Linux Kernel APIs. Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

Diffstat (limited to 'test/v4l2_device')

0 files changed, 0 insertions, 0 deletions

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * v4l2_device.cpp - Common base for V4L2 video devices and subdevices
 */

#include "v4l2_device.h"

#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

#include "log.h"
#include "v4l2_controls.h"

/**
 * \file v4l2_device.h
 * \brief Common base for V4L2 devices and subdevices
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(V4L2)

/**
 * \class V4L2Device
 * \brief Base class for V4L2VideoDevice and V4L2Subdevice
 *
 * The V4L2Device class groups together the methods and fields common to
 * both the V4L2VideoDevice and V4L2Subdevice classes, and provides a base
 * class with methods to open and close the device node associated with the
 * device and to perform IOCTL system calls on it.
 *
 * The V4L2Device class cannot be instantiated directly, as its constructor
 * is protected. Users should instead create instances of one the derived
 * classes to model either a V4L2 video device or a V4L2 subdevice.
 */

/**
 * \brief Construct a V4L2Device
 * \param[in] deviceNode The device node filesystem path
 *
 * Initialize the file descriptor to -1 and store the \a deviceNode to be used
 * at open() time, and the \a logTag to prefix log messages with.
 */
V4L2Device::V4L2Device(const std::string &deviceNode)
	: deviceNode_(deviceNode), fd_(-1)
{
}

/**
 * \brief Destroy a V4L2Device
 */
V4L2Device::~V4L2Device()
{
}

/**
 * \brief Open a V4L2 device node
 * \param[in] flags Access mode flags
 *
 * Open the device node path with the provided access mode \a flags and
 * initialize the file descriptor, which was initially set to -1.
 *
 * \return 0 on success or a negative error code otherwise
 */
int V4L2Device::open(unsigned int flags)
{
	if (isOpen()) {
		LOG(V4L2, Error) << "Device already open";
		return -EBUSY;
	}

	int ret = ::open(deviceNode_.c_str(), flags);
	if (ret < 0) {
		ret = -errno;
		LOG(V4L2, Error) << "Failed to open V4L2 device: "
				 << strerror(-ret);
		return ret;
	}

	fd_ = ret;

	listControls();

	return 0;
}

/**
 * \brief Set the file descriptor of a V4L2 device
 * \param[in] fd The file descriptor handle
 *
 * This method allows a device to provide an already opened file descriptor
 * referring to the V4L2 device node, instead of opening it with open(). This
 * can be used for V4L2 M2M devices where a single video device node is used for
 * both the output and capture devices, or when receiving an open file
 * descriptor in a context that doesn't have permission to open the device node
 * itself.
 *


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