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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2021, Google Inc.
*
* mapped_framebuffer.cpp - Mapped Framebuffer support
*/
#include "libcamera/internal/mapped_framebuffer.h"
#include <algorithm>
#include <errno.h>
#include <map>
#include <sys/mman.h>
#include <unistd.h>
#include <libcamera/base/log.h>
/**
* \file libcamera/internal/mapped_framebuffer.h
* \brief Frame buffer memory mapping support
*/
namespace libcamera {
LOG_DECLARE_CATEGORY(Buffer)
/**
* \class MappedBuffer
* \brief Provide an interface to support managing memory mapped buffers
*
* The MappedBuffer interface provides access to a set of MappedPlanes which
* are available for access by the CPU.
*
* This class is not meant to be constructed directly, but instead derived
* classes should be used to implement the correct mapping of a source buffer.
*
* This allows treating CPU accessible memory through a generic interface
* regardless of whether it originates from a libcamera FrameBuffer or other
* source.
*/
/**
* \typedef MappedBuffer::Plane
* \brief A mapped region of memory accessible to the CPU
*
* The MappedBuffer::Plane uses the Span interface to describe the mapped memory
* region.
*/
/**
* \brief Construct an empty MappedBuffer
*/
MappedBuffer::MappedBuffer()
: error_(0)
{
}
/**
* \brief Move constructor, construct the MappedBuffer with the contents of \a
* other using move semantics
* \param[in] other The other MappedBuffer
*
* Moving a MappedBuffer moves the mappings contained in the \a other to the new
* MappedBuffer and invalidates the \a other.
*
* No mappings are unmapped or destroyed in this process.
*/
MappedBuffer::MappedBuffer(MappedBuffer &&other)
{
*this = std::move(other);
}
/**
* \brief Move assignment operator, replace the mappings with those of \a other
* \param[in] other The other MappedBuffer
*
* Moving a MappedBuffer moves the mappings contained in the \a other to the new
* MappedBuffer and invalidates the \a other.
*
* No mappings are unmapped or destroyed in this process.
*/
MappedBuffer &MappedBuffer::operator=(MappedBuffer &&other)
{
error_ = other.error_;
planes_ = std::move(other.planes_);
maps_ = std::move(other.maps_);
other.error_ = -ENOENT;
return *this;
}
MappedBuffer::~MappedBuffer()
{
for (Plane &map : maps_)
munmap(map.data(), map.size());
}
/**
* \fn MappedBuffer::isValid()
* \brief Check if the MappedBuffer instance is valid
* \return True if the MappedBuffer has valid mappings, false otherwise
*/
/**
* \fn MappedBuffer::error()
* \brief Retrieve the map error status
*
* This function retrieves the error status from the MappedBuffer.
* The error status is a negative number as defined by errno.h. If
* no error occurred, this function returns 0.
*
* \return The map error code
*/
/**
* \fn MappedBuffer::planes()
* \brief Retrieve the mapped planes
*
* This function retrieves the successfully mapped planes stored as a vector
* of Span<uint8_t> to provide access to the mapped memory.
*
* \return A vector of the mapped planes
*/
/**
* \var MappedBuffer::error_
* \brief Stores the error value if present
*
* MappedBuffer derived classes shall set this to a negative value as defined
* by errno.h if an error occured during the mapping process.
*/
/**
* \var MappedBuffer::planes_
* \brief Stores the internal mapped planes
*
* MappedBuffer derived classes shall store the mappings they create in this
* vector which points the beginning of mapped plane addresses.
*/
/**
* \var MappedBuffer::maps_
* \brief Stores the mapped buffer
*
* MappedBuffer derived classes shall store the mappings they create in this
* vector which is parsed during destruct to unmap any memory mappings which
* completed successfully.
*/
/**
* \class MappedFrameBuffer
* \brief Map a FrameBuffer using the MappedBuffer interface
*/
/**
* \enum MappedFrameBuffer::MapFlag
* \brief Specify the mapping mode for the FrameBuffer
* \var MappedFrameBuffer::Read
* \brief Create a read-only mapping
* \var MappedFrameBuffer::Write
* \brief Create a write-only mapping
* \var MappedFrameBuffer::ReadWrite
* \brief Create a mapping that can be both read and written
*/
/**
* \typedef MappedFrameBuffer::MapFlags
* \brief A bitwise combination of MappedFrameBuffer::MapFlag values
*/
/**
* \brief Map all planes of a FrameBuffer
* \param[in] buffer FrameBuffer to be mapped
* \param[in] flags Protection flags to apply to map
*
* Construct an object to map a frame buffer for CPU access. The mapping can be
* made as Read only, Write only or support Read and Write operations by setting
* the MapFlag flags accordingly.
*/
MappedFrameBuffer::MappedFrameBuffer(const FrameBuffer *buffer, MapFlags flags)
{
ASSERT(!buffer->planes().empty());
planes_.reserve(buffer->planes().size());
int mmapFlags = 0;
if (flags & MapFlag::Read)
mmapFlags |= PROT_READ;
if (flags & MapFlag::Write)
mmapFlags |= PROT_WRITE;
struct MappedBufferInfo {
uint8_t *address = nullptr;
size_t mapLength = 0;
size_t dmabufLength = 0;
};
std::map<int, MappedBufferInfo> mappedBuffers;
for (const FrameBuffer::Plane &plane : buffer->planes()) {
const int fd = plane.fd.get();
if (mappedBuffers.find(fd) == mappedBuffers.end()) {
const size_t length = lseek(fd, 0, SEEK_END);
mappedBuffers[fd] = MappedBufferInfo{ nullptr, 0, length };
}
const size_t length = mappedBuffers[fd].dmabufLength;
if (plane.offset > length ||
plane.offset + plane.length > length) {
LOG(Buffer, Fatal) << "plane is out of buffer: "
<< "buffer length=" << length
<< ", plane offset=" << plane.offset
<< ", plane length=" << plane.length;
return;
}
size_t &mapLength = mappedBuffers[fd].mapLength;
mapLength = std::max(mapLength,
static_cast<size_t>(plane.offset + plane.length));
}
for (const FrameBuffer::Plane &plane : buffer->planes()) {
const int fd = plane.fd.get();
auto &info = mappedBuffers[fd];
if (!info.address) {
void *address = mmap(nullptr, info.mapLength, mmapFlags,
MAP_SHARED, fd, 0);
if (address == MAP_FAILED) {
error_ = -errno;
LOG(Buffer, Error) << "Failed to mmap plane: "
<< strerror(-error_);
return;
}
info.address = static_cast<uint8_t *>(address);
maps_.emplace_back(info.address, info.mapLength);
}
planes_.emplace_back(info.address + plane.offset, plane.length);
}
}
} /* namespace libcamera */
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