1 files changed, 124 insertions, 0 deletions
diff --git a/src/libcamera/dma_heaps.cpp b/src/libcamera/dma_heaps.cpp
new file mode 100644
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+++ b/src/libcamera/dma_heaps.cpp
@@ -0,0 +1,124 @@
+/* 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 */