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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2020, Raspberry Pi Ltd
*
* dma_heaps.cpp - Helper class for dma-heap allocations.
*/
#include "libcamera/internal/dma_heaps.h"
#include <array>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <linux/dma-buf.h>
#include <linux/dma-heap.h>
#include <libcamera/base/log.h>
/**
* \file dma_heaps.cpp
* \brief CMA dma-heap allocator
*/
/*
* /dev/dma_heap/linux,cma is the dma-heap allocator, which allows dmaheap-cma
* to only have to worry about importing.
*
* Annoyingly, should the cma heap size be specified on the kernel command line
* instead of DT, the heap gets named "reserved" instead.
*/
static constexpr std::array<const char *, 2> heapNames = {
"/dev/dma_heap/linux,cma",
"/dev/dma_heap/reserved"
};
namespace libcamera {
LOG_DEFINE_CATEGORY(DmaHeap)
/**
* \class DmaHeap
* \brief Helper class for CMA dma-heap allocations
*/
/**
* \brief Construct a DmaHeap that owns a CMA dma-heap file descriptor
*
* Looks for a CMA dma-heap device to use. If it fails to open any dma-heap
* device, an invalid DmaHeap object is constructed.
*
* Check the new DmaHeap object with isValid before using it.
*/
DmaHeap::DmaHeap()
{
for (const char *name : heapNames) {
int ret = ::open(name, O_RDWR | O_CLOEXEC, 0);
if (ret < 0) {
ret = errno;
LOG(DmaHeap, Debug)
<< "Failed to open " << name << ": "
<< strerror(ret);
continue;
}
dmaHeapHandle_ = UniqueFD(ret);
break;
}
if (!dmaHeapHandle_.isValid())
LOG(DmaHeap, Error) << "Could not open any dmaHeap device";
}
/**
* \brief Destroy the DmaHeap instance
*/
DmaHeap::~DmaHeap() = default;
/**
* \fn DmaHeap::isValid()
* \brief Check if the DmaHeap instance is valid
* \return True if the DmaHeap is valid, false otherwise
*/
/**
* \brief Allocate a dma-buf from the DmaHeap
* \param [in] name The name to set for the allocated buffer
* \param [in] size The size of the buffer to allocate
*
* Allocates a dma-buf with read/write access.
*
* If the allocation fails, return an invalid UniqueFD.
*
* \return The UniqueFD of the allocated buffer
*/
UniqueFD DmaHeap::alloc(const char *name, std::size_t size)
{
int ret;
if (!name)
return {};
struct dma_heap_allocation_data alloc = {};
alloc.len = size;
alloc.fd_flags = O_CLOEXEC | O_RDWR;
ret = ::ioctl(dmaHeapHandle_.get(), DMA_HEAP_IOCTL_ALLOC, &alloc);
if (ret < 0) {
LOG(DmaHeap, Error) << "dmaHeap allocation failure for " << name;
return {};
}
UniqueFD allocFd(alloc.fd);
ret = ::ioctl(allocFd.get(), DMA_BUF_SET_NAME, name);
if (ret < 0) {
LOG(DmaHeap, Error) << "dmaHeap naming failure for " << name;
return {};
}
return allocFd;
}
} /* namespace libcamera */
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