create PX4 platform layer initialization helper (#11269)

- starts requirements for PX4 modules (hrt, param, etc)

platforms/nuttx/src/px4_layer/CMakeLists.txt

@@ -37,8 +37,14 @@ if (NOT ${PX4_BOARD} MATCHES "px4_io")
 	add_library(px4_layer
 		px4_nuttx_tasks.c
 		px4_nuttx_impl.cpp
+		px4_init.cpp
 	)
-	target_link_libraries(px4_layer PRIVATE nuttx_sched drivers_boards_common_arch)
+	target_link_libraries(px4_layer
+		PRIVATE
+			nuttx_apps # up_cxxinitialize
+			nuttx_sched
+			drivers_boards_common_arch
+		)
 else()
 	add_library(px4_layer ${PX4_SOURCE_DIR}/src/platforms/empty.c)
 endif()

platforms/nuttx/src/px4_layer/px4_init.cpp

@@ -0,0 +1,69 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2019 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#include "px4_init.h"
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <drivers/drv_hrt.h>
+#include <lib/parameters/param.h>
+#include <systemlib/cpuload.h>
+
+#include "platform/cxxinitialize.h"
+
+int px4_platform_init(void)
+{
+
+#if defined(CONFIG_HAVE_CXX) && defined(CONFIG_HAVE_CXXINITIALIZE)
+	/* run C++ ctors before we go any further */
+	up_cxxinitialize();
+
+#	if defined(CONFIG_EXAMPLES_NSH_CXXINITIALIZE)
+#  		error CONFIG_EXAMPLES_NSH_CXXINITIALIZE Must not be defined! Use CONFIG_HAVE_CXX and CONFIG_HAVE_CXXINITIALIZE.
+#	endif
+
+#else
+#  error platform is dependent on c++ both CONFIG_HAVE_CXX and CONFIG_HAVE_CXXINITIALIZE must be defined.
+#endif
+
+	hrt_init();
+
+	param_init();
+
+	/* configure CPU load estimation */
+#ifdef CONFIG_SCHED_INSTRUMENTATION
+	cpuload_initialize_once();
+#endif
+
+	return PX4_OK;
+}