android: Introduce CameraBuffer interface

In order to provide support for different memory backends,
move the MappedCamera3Buffer class definition outside of the
CameraDevice class to its own file and rename it in CameraBuffer.

The interface defined in camera_buffer.h will be implemented by
different backends that will be placed in the src/android/mm
subdirectory.

Provide a first implementation for the 'generic android' backend
which matches the existing one.

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

src/android/camera_buffer.h

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * camera_buffer.h - Frame buffer handling interface definition
+ */
+#ifndef __ANDROID_CAMERA_BUFFER_H__
+#define __ANDROID_CAMERA_BUFFER_H__
+
+#include <hardware/camera3.h>
+
+#include <libcamera/internal/buffer.h>
+
+class CameraBuffer : public libcamera::MappedBuffer
+{
+public:
+	CameraBuffer(const buffer_handle_t camera3buffer, int flags);
+	~CameraBuffer();
+};
+
+#endif /* __ANDROID_CAMERA_BUFFER_H__ */

src/android/camera_device.cpp

@@ -257,36 +257,6 @@ void sortCamera3StreamConfigs(std::vector<Camera3StreamConfig> &unsortedConfigs,
 
 } /* namespace */
 
-MappedCamera3Buffer::MappedCamera3Buffer(const buffer_handle_t camera3buffer,
-					 int flags)
-{
-	maps_.reserve(camera3buffer->numFds);
-	error_ = 0;
-
-	for (int i = 0; i < camera3buffer->numFds; i++) {
-		if (camera3buffer->data[i] == -1)
-			continue;
-
-		off_t length = lseek(camera3buffer->data[i], 0, SEEK_END);
-		if (length < 0) {
-			error_ = -errno;
-			LOG(HAL, Error) << "Failed to query plane length";
-			break;
-		}
-
-		void *address = mmap(nullptr, length, flags, MAP_SHARED,
-				     camera3buffer->data[i], 0);
-		if (address == MAP_FAILED) {
-			error_ = -errno;
-			LOG(HAL, Error) << "Failed to mmap plane";
-			break;
-		}
-
-		maps_.emplace_back(static_cast<uint8_t *>(address),
-				   static_cast<size_t>(length));
-	}
-}
-
 /*
  * \struct Camera3RequestDescriptor
  *
@@ -1892,7 +1862,7 @@ void CameraDevice::requestComplete(Request *request)
 		 * separate thread.
 		 */
 
-		MappedCamera3Buffer mapped(*descriptor->buffers_[i].buffer,
+		CameraBuffer mapped(*descriptor->buffers_[i].buffer,
 				    PROT_READ | PROT_WRITE);
 		if (!mapped.isValid()) {
 			LOG(HAL, Error) << "Failed to mmap android blob buffer";

src/android/camera_device.h

@@ -24,17 +24,12 @@
 #include "libcamera/internal/log.h"
 #include "libcamera/internal/message.h"
 
+#include "camera_buffer.h"
 #include "camera_metadata.h"
 #include "camera_stream.h"
 #include "camera_worker.h"
 #include "jpeg/encoder.h"
 
-class MappedCamera3Buffer : public libcamera::MappedBuffer
-{
-public:
-	MappedCamera3Buffer(const buffer_handle_t camera3buffer, int flags);
-};
-
 class CameraDevice : protected libcamera::Loggable
 {
 public:

src/android/meson.build

@@ -52,6 +52,8 @@ android_hal_sources = files([
     'yuv/post_processor_yuv.cpp'
 ])
 
+subdir('mm')
+
 android_camera_metadata_sources = files([
     'metadata/camera_metadata.c',
 ])

src/android/mm/generic_camera_buffer.cpp

@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2021, Google Inc.
+ *
+ * generic_camera_buffer.cpp - Generic Android frame buffer backend
+ */
+
+#include "../camera_buffer.h"
+
+#include "libcamera/internal/log.h"
+
+using namespace libcamera;
+
+LOG_DECLARE_CATEGORY(HAL)
+
+CameraBuffer::CameraBuffer(const buffer_handle_t camera3buffer, int flags)
+{
+	maps_.reserve(camera3buffer->numFds);
+	error_ = 0;
+
+	for (int i = 0; i < camera3buffer->numFds; i++) {
+		if (camera3buffer->data[i] == -1)
+			continue;
+
+		off_t length = lseek(camera3buffer->data[i], 0, SEEK_END);
+		if (length < 0) {
+			error_ = -errno;
+			LOG(HAL, Error) << "Failed to query plane length";
+			break;
+		}
+
+		void *address = mmap(nullptr, length, flags, MAP_SHARED,
+				     camera3buffer->data[i], 0);
+		if (address == MAP_FAILED) {
+			error_ = -errno;
+			LOG(HAL, Error) << "Failed to mmap plane";
+			break;
+		}
+
+		maps_.emplace_back(static_cast<uint8_t *>(address),
+				   static_cast<size_t>(length));
+	}
+}
+
+CameraBuffer::~CameraBuffer()
+{
+}

src/android/mm/meson.build

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: CC0-1.0
+
+platform = get_option('android_platform')
+if platform == 'generic'
+    android_hal_sources += files(['generic_camera_buffer.cpp'])
+endif