android: Introduce PlatformFrameBufferAllocator

The existing FrameBufferAllocator is not allowed to allocate a
new buffer while Camera is running. This introduces
PlatformFrameBufferAllocator. It allocates FrameBuffer using
cros::CameraBufferManager on ChromeOS and gralloc on non ChromeOS
platform. The allocated FrameBuffer owns the underlying buffer
but must be destroyed before PlatformFrameBufferAllocator is
destroyed.

Signed-off-by: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/android/mm/generic_frame_buffer_allocator.cpp

@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * generic_camera_buffer.cpp - Allocate FrameBuffer using gralloc API
+ */
+
+#include <memory>
+#include <vector>
+
+#include <libcamera/base/log.h>
+#include <libcamera/base/shared_fd.h>
+
+#include "libcamera/internal/formats.h"
+#include "libcamera/internal/framebuffer.h"
+
+#include <hardware/camera3.h>
+#include <hardware/gralloc.h>
+#include <hardware/hardware.h>
+
+#include "../camera_device.h"
+#include "../frame_buffer_allocator.h"
+
+using namespace libcamera;
+
+LOG_DECLARE_CATEGORY(HAL)
+
+namespace {
+class GenericFrameBufferData : public FrameBuffer::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(FrameBuffer)
+
+public:
+	GenericFrameBufferData(struct alloc_device_t *allocDevice,
+			       buffer_handle_t handle)
+		: allocDevice_(allocDevice), handle_(handle)
+	{
+		ASSERT(allocDevice_);
+		ASSERT(handle_);
+	}
+
+	~GenericFrameBufferData() override
+	{
+		/*
+		 * allocDevice_ is used to destroy handle_. allocDevice_ is
+		 * owned by PlatformFrameBufferAllocator::Private.
+		 * GenericFrameBufferData must be destroyed before it is
+		 * destroyed.
+		 *
+		 * \todo Consider managing alloc_device_t with std::shared_ptr
+		 * if this is difficult to maintain.
+		 *
+		 * \todo Thread safety against alloc_device_t is not documented.
+		 * Is it no problem to call alloc/free in parallel?
+		 */
+		allocDevice_->free(allocDevice_, handle_);
+	}
+
+private:
+	struct alloc_device_t *allocDevice_;
+	const buffer_handle_t handle_;
+};
+} /* namespace */
+
+class PlatformFrameBufferAllocator::Private : public Extensible::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(PlatformFrameBufferAllocator)
+
+public:
+	Private(CameraDevice *const cameraDevice)
+		: cameraDevice_(cameraDevice),
+		  hardwareModule_(cameraDevice->camera3Device()->common.module),
+		  allocDevice_(nullptr)
+	{
+		ASSERT(hardwareModule_);
+	}
+
+	~Private() override;
+
+	std::unique_ptr<libcamera::FrameBuffer>
+	allocate(int halPixelFormat, const libcamera::Size &size, uint32_t usage);
+
+private:
+	const CameraDevice *const cameraDevice_;
+	struct hw_module_t *const hardwareModule_;
+	struct alloc_device_t *allocDevice_;
+};
+
+PlatformFrameBufferAllocator::Private::~Private()
+{
+	if (allocDevice_)
+		gralloc_close(allocDevice_);
+}
+
+std::unique_ptr<libcamera::FrameBuffer>
+PlatformFrameBufferAllocator::Private::allocate(int halPixelFormat,
+						const libcamera::Size &size,
+						uint32_t usage)
+{
+	if (!allocDevice_) {
+		int ret = gralloc_open(hardwareModule_, &allocDevice_);
+		if (ret) {
+			LOG(HAL, Fatal) << "gralloc_open() failed: " << ret;
+			return nullptr;
+		}
+	}
+
+	int stride = 0;
+	buffer_handle_t handle = nullptr;
+	int ret = allocDevice_->alloc(allocDevice_, size.width, size.height,
+				      halPixelFormat, usage, &handle, &stride);
+	if (ret) {
+		LOG(HAL, Error) << "failed buffer allocation: " << ret;
+		return nullptr;
+	}
+	if (!handle) {
+		LOG(HAL, Fatal) << "invalid buffer_handle_t";
+		return nullptr;
+	}
+
+	/* This code assumes the planes are mapped consecutively. */
+	const libcamera::PixelFormat pixelFormat =
+		cameraDevice_->capabilities()->toPixelFormat(halPixelFormat);
+	const auto &info = PixelFormatInfo::info(pixelFormat);
+	std::vector<FrameBuffer::Plane> planes(info.numPlanes());
+
+	SharedFD fd{ handle->data[0] };
+	size_t offset = 0;
+	for (auto [i, plane] : utils::enumerate(planes)) {
+		const size_t planeSize = info.planeSize(size.height, i, stride);
+
+		plane.fd = fd;
+		plane.offset = offset;
+		plane.length = planeSize;
+		offset += planeSize;
+	}
+
+	return std::make_unique<FrameBuffer>(
+		std::make_unique<GenericFrameBufferData>(allocDevice_, handle),
+		planes);
+}
+
+PUBLIC_FRAME_BUFFER_ALLOCATOR_IMPLEMENTATION