android: Introduce Chromium OS buffer manager

Introduce the CameraBuffer backend for the Chromium OS operating system
and the associated meson option.

The Chromium OS CameraBuffer implementation uses the
cros::CameraBufferManager class to perform mapping of 1 plane and multiplane
buffers and to retrieve size information.

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

meson_options.txt

@@ -7,7 +7,7 @@ option('android',
 
 option('android_platform',
         type : 'combo',
-        choices : ['generic'],
+        choices : ['cros', 'generic'],
         value : 'generic',
         description : 'Select the Android platform to compile for')
 

src/android/mm/cros_camera_buffer.cpp

@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * cros_camera_buffer.cpp - Chromium OS buffer backend using CameraBufferManager
+ */
+
+#include "../camera_buffer.h"
+
+#include "libcamera/internal/log.h"
+
+#include "cros-camera/camera_buffer_manager.h"
+
+using namespace libcamera;
+
+LOG_DECLARE_CATEGORY(HAL)
+
+class CameraBuffer::Private : public Extensible::Private
+{
+	LIBCAMERA_DECLARE_PUBLIC(CameraBuffer)
+
+public:
+	Private(CameraBuffer *cameraBuffer,
+		buffer_handle_t camera3Buffer, int flags);
+	~Private();
+
+	bool isValid() const { return valid_; }
+
+	unsigned int numPlanes() const;
+
+	Span<uint8_t> plane(unsigned int plane);
+
+	size_t jpegBufferSize(size_t maxJpegBufferSize) const;
+
+private:
+	cros::CameraBufferManager *bufferManager_;
+	buffer_handle_t handle_;
+	unsigned int numPlanes_;
+	bool valid_;
+	union {
+		void *addr;
+		android_ycbcr ycbcr;
+	} mem;
+
+	const uint8_t *planeAddr(unsigned int plane) const;
+	uint8_t *planeAddr(unsigned int plane);
+};
+
+CameraBuffer::Private::Private(CameraBuffer *cameraBuffer,
+			       buffer_handle_t camera3Buffer, int flags)
+	: Extensible::Private(cameraBuffer), handle_(camera3Buffer),
+	  numPlanes_(0), valid_(false)
+{
+	bufferManager_ = cros::CameraBufferManager::GetInstance();
+
+	bufferManager_->Register(camera3Buffer);
+
+	numPlanes_ = bufferManager_->GetNumPlanes(camera3Buffer);
+	switch (numPlanes_) {
+	case 1: {
+		int ret = bufferManager_->Lock(handle_, 0, 0, 0, 0, 0, &mem.addr);
+		if (ret) {
+			LOG(HAL, Error) << "Single plane buffer mapping failed";
+			return;
+		}
+		break;
+	}
+	case 2:
+	case 3: {
+		int ret = bufferManager_->LockYCbCr(handle_, 0, 0, 0, 0, 0,
+						    &mem.ycbcr);
+		if (ret) {
+			LOG(HAL, Error) << "YCbCr buffer mapping failed";
+			return;
+		}
+		break;
+	}
+	default:
+		LOG(HAL, Error) << "Invalid number of planes: " << numPlanes_;
+		return;
+	}
+
+	valid_ = true;
+}
+
+CameraBuffer::Private::~Private()
+{
+	bufferManager_->Unlock(handle_);
+	bufferManager_->Deregister(handle_);
+}
+
+unsigned int CameraBuffer::Private::numPlanes() const
+{
+	return bufferManager_->GetNumPlanes(handle_);
+}
+
+Span<uint8_t> CameraBuffer::Private::plane(unsigned int plane)
+{
+	void *addr;
+
+	switch (numPlanes()) {
+	case 1:
+		addr = mem.addr;
+		break;
+	default:
+		switch (plane) {
+		case 1:
+			addr = mem.ycbcr.y;
+			break;
+		case 2:
+			addr = mem.ycbcr.cb;
+			break;
+		case 3:
+			addr = mem.ycbcr.cr;
+			break;
+		}
+	}
+
+	return { static_cast<uint8_t *>(addr),
+		 bufferManager_->GetPlaneSize(handle_, plane) };
+}
+
+size_t CameraBuffer::Private::jpegBufferSize(size_t maxJpegBufferSize) const
+{
+	return bufferManager_->GetPlaneSize(handle_, 0);
+}
+
+PUBLIC_CAMERA_BUFFER_IMPLEMENTATION

src/android/mm/meson.build

@@ -3,4 +3,7 @@
 platform = get_option('android_platform')
 if platform == 'generic'
     android_hal_sources += files(['generic_camera_buffer.cpp'])
+elif platform == 'cros'
+    android_hal_sources += files(['cros_camera_buffer.cpp'])
+    android_deps += [dependency('libcros_camera')]
 endif