From patchwork Tue Nov 26 23:35:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Niklas_S=C3=B6derlund?= X-Patchwork-Id: 2353 Return-Path: Received: from bin-mail-out-05.binero.net (bin-mail-out-05.binero.net [195.74.38.228]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id D538761C59 for ; Wed, 27 Nov 2019 00:39:28 +0100 (CET) X-Halon-ID: fbea2f08-10a5-11ea-a0b9-005056917f90 Authorized-sender: niklas@soderlund.pp.se Received: from bismarck.berto.se (p54ac5865.dip0.t-ipconnect.de [84.172.88.101]) by bin-vsp-out-02.atm.binero.net (Halon) with ESMTPA id fbea2f08-10a5-11ea-a0b9-005056917f90; Wed, 27 Nov 2019 00:39:27 +0100 (CET) From: =?utf-8?q?Niklas_S=C3=B6derlund?= To: libcamera-devel@lists.libcamera.org Date: Wed, 27 Nov 2019 00:35:55 +0100 Message-Id: <20191126233620.1695316-6-niklas.soderlund@ragnatech.se> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191126233620.1695316-1-niklas.soderlund@ragnatech.se> References: <20191126233620.1695316-1-niklas.soderlund@ragnatech.se> MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH 05/30] libcamera: buffer: Add Dmabuf to describe a dma buffer X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 26 Nov 2019 23:39:29 -0000 A FrameBuffer object that holds a frame captured from a sensor consists of one or more plane(s). The memory of each plane can be accessed by using a dma buffer. Add a class that describes a dmabuf to make it easy for applications and IPAs to interact with memory. Signed-off-by: Niklas Söderlund --- include/libcamera/buffer.h | 19 +++++++ src/libcamera/buffer.cpp | 113 +++++++++++++++++++++++++++++++++++++ 2 files changed, 132 insertions(+) diff --git a/include/libcamera/buffer.h b/include/libcamera/buffer.h index 33793b4ccf881eda..3c430afbfe8e9a05 100644 --- a/include/libcamera/buffer.h +++ b/include/libcamera/buffer.h @@ -58,6 +58,25 @@ private: int fd_; }; +class Dmabuf final +{ +public: + Dmabuf(int fd, unsigned int length); + ~Dmabuf(); + + int fd() const { return fd_.fd(); } + unsigned int length() const { return length_; } + void *mem(); + +private: + int mmap(); + int munmap(); + + FileDescriptor fd_; + unsigned int length_; + void *mem_; +}; + class Plane final { public: diff --git a/src/libcamera/buffer.cpp b/src/libcamera/buffer.cpp index 0676586ae3be2a61..5516055b2ea885c2 100644 --- a/src/libcamera/buffer.cpp +++ b/src/libcamera/buffer.cpp @@ -177,6 +177,119 @@ FileDescriptor::~FileDescriptor() * an image may or may not be contiguous. */ +/** + * \class Dmabuf + * \brief A memory region to store a single plane of a frame + * + * Planar pixel formats use multiple memory regions to store planes + * corresponding to the different colour components of a frame. The Dmabuf class + * tracks the specific details of a memory region used to store a single plane + * for a given frame and provides the means to access the memory, both for the + * application and for DMA. A Buffer then contains one or multiple planes + * depending on its pixel format. + * + * To support DMA access, planes are associated with dmabuf objects represented + * by file handles. Each plane carries a dmabuf file handle and an offset within + * the buffer. Those file handles may refer to the same dmabuf object, depending + * on whether the devices accessing the memory regions composing the image + * support non-contiguous DMA to planes ore require DMA-contiguous memory. + * + * To support CPU access, planes carry the CPU address of their backing memory. + * Similarly to the dmabuf file handles, the CPU addresses for planes composing + * an image may or may not be contiguous. + */ + +/** + * \brief Set the dmabuf file handle backing the buffer + * \param[in] fd The dmabuf file handle + * \param[in] length The size of the memory region + * + * The \a fd dmabuf file handle is duplicated and stored. + */ +Dmabuf::Dmabuf(int fd, unsigned int length) + : fd_(fd), length_(length), mem_(nullptr) +{ +} + +Dmabuf::~Dmabuf() +{ + munmap(); +} + +/** + * \fn Dmabuf::fd() + * \brief Get the dmabuf file handle backing the buffer + */ + +/** + * \fn Dmabuf::length() + * \brief Retrieve the length of the memory region + * \return The length of the memory region + */ + +/** + * \fn Dmabuf::mem() + * \brief Retrieve the CPU accessible memory address of the Dmabuf + * \return The CPU accessible memory address on success or nullptr otherwise. + */ +void *Dmabuf::mem() +{ + if (!mem_) + mmap(); + + return mem_; +} + +/** + * \brief Map the plane memory data to a CPU accessible address + * + * \return 0 on success or a negative error code otherwise + */ +int Dmabuf::mmap() +{ + void *map; + + if (mem_) + return 0; + + map = ::mmap(NULL, length_, PROT_READ | PROT_WRITE, MAP_SHARED, fd_.fd(), 0); + if (map == MAP_FAILED) { + int ret = -errno; + LOG(Buffer, Error) + << "Failed to mmap plane: " << strerror(-ret); + return ret; + } + + mem_ = map; + + return 0; +} + +/** + * \brief Unmap any existing CPU accessible mapping + * + * Unmap the memory mapped by an earlier call to mmap(). + * + * \return 0 on success or a negative error code otherwise + */ +int Dmabuf::munmap() +{ + int ret = 0; + + if (mem_) + ret = ::munmap(mem_, length_); + + if (ret) { + ret = -errno; + LOG(Buffer, Warning) + << "Failed to unmap plane: " << strerror(-ret); + } else { + mem_ = 0; + } + + return ret; +} + Plane::Plane() : fd_(-1), length_(0), mem_(0) {