1 files changed, 90 insertions, 0 deletions
diff --git a/src/libcamera/pipeline/rpi/vc4/dma_heaps.cpp b/src/libcamera/pipeline/rpi/vc4/dma_heaps.cpp
new file mode 100644
index 00000000..317b1fc1
--- /dev/null
+++ b/src/libcamera/pipeline/rpi/vc4/dma_heaps.cpp
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Raspberry Pi Ltd
+ *
+ * dma_heaps.h - Helper class for dma-heap allocations.
+ */
+
+#include "dma_heaps.h"
+
+#include <array>
+#include <fcntl.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-heap.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include <libcamera/base/log.h>
+
+/*
+ * /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_DECLARE_CATEGORY(RPI)
+
+namespace RPi {
+
+DmaHeap::DmaHeap()
+{
+	for (const char *name : heapNames) {
+		int ret = ::open(name, O_RDWR | O_CLOEXEC, 0);
+		if (ret < 0) {
+			ret = errno;
+			LOG(RPI, Debug) << "Failed to open " << name << ": "
+					<< strerror(ret);
+			continue;
+		}
+
+		dmaHeapHandle_ = UniqueFD(ret);
+		break;
+	}
+
+	if (!dmaHeapHandle_.isValid())
+		LOG(RPI, Error) << "Could not open any dmaHeap device";
+}
+
+DmaHeap::~DmaHeap() = default;
+
+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(RPI, Error) << "dmaHeap allocation failure for "
+				<< name;
+		return {};
+	}
+
+	UniqueFD allocFd(alloc.fd);
+	ret = ::ioctl(allocFd.get(), DMA_BUF_SET_NAME, name);
+	if (ret < 0) {
+		LOG(RPI, Error) << "dmaHeap naming failure for "
+				<< name;
+		return {};
+	}
+
+	return allocFd;
+}
+
+} /* namespace RPi */
+
+} /* namespace libcamera */