src/v4l2/v4l2_camera_proxy.cpp


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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * v4l2_camera_proxy.cpp - Proxy to V4L2 compatibility camera
 */

#include "v4l2_camera_proxy.h"

#include <algorithm>
#include <array>
#include <errno.h>
#include <linux/drm_fourcc.h>
#include <linux/videodev2.h>
#include <string.h>
#include <sys/mman.h>

#include <libcamera/camera.h>
#include <libcamera/object.h>

#include "log.h"
#include "utils.h"
#include "v4l2_camera.h"
#include "v4l2_compat_manager.h"

#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + (c))

using namespace libcamera;

LOG_DECLARE_CATEGORY(V4L2Compat);

V4L2CameraProxy::V4L2CameraProxy(unsigned int index,
				 std::shared_ptr<Camera> camera)
	: refcount_(0), index_(index), bufferCount_(0), currentBuf_(0),
	  vcam_(std::make_unique<V4L2Camera>(camera))
{
	querycap(camera);
}

int V4L2CameraProxy::open(bool nonBlocking)
{
	LOG(V4L2Compat, Debug) << "Servicing open";

	int ret = vcam_->invokeMethod(&V4L2Camera::open,
				      ConnectionTypeBlocking);
	if (ret < 0) {
		errno = -ret;
		return -1;
	}

	nonBlocking_ = nonBlocking;

	vcam_->invokeMethod(&V4L2Camera::getStreamConfig,
			    ConnectionTypeBlocking, &streamConfig_);
	setFmtFromConfig(streamConfig_);
	sizeimage_ = calculateSizeImage(streamConfig_);

	refcount_++;

	return 0;
}

void V4L2CameraProxy::dup()
{
	refcount_++;
}

void V4L2CameraProxy::close()
{
	LOG(V4L2Compat, Debug) << "Servicing close";

	if (--refcount_ > 0)
		return;

	vcam_->invokeMethod(&V4L2Camera::close, ConnectionTypeBlocking);
}

void *V4L2CameraProxy::mmap(void *addr, size_t length, int prot, int flags,
			    off_t offset)
{
	LOG(V4L2Compat, Debug) << "Servicing mmap";

	/* \todo Validate prot and flags properly. */
	if (prot != (PROT_READ | PROT_WRITE)) {
		errno = EINVAL;
		return MAP_FAILED;
	}

	unsigned int index = offset / sizeimage_;
	if (index * sizeimage_ != offset || length != sizeimage_) {
		errno = EINVAL;
		return MAP_FAILED;
	}

	FileDescriptor fd = vcam_->getBufferFd(index);
	if (!fd.isValid()) {
		errno = EINVAL;
		return MAP_FAILED;
	}

	void *map = V4L2CompatManager::instance()->fops().mmap(addr, length, prot,
							       flags, fd.fd(), 0);
	if (map == MAP_FAILED)
		return map;

	buffers_[index].flags |= V4L2_BUF_FLAG_MAPPED;
	mmaps_[map] = index;

	return map;