fmu-v2: add bootloader binary and SYS_BL_UPDATE param for BL updates

This allows a simple-to-use bootloader update mechanism to switch from
fmu-v2 to fmu-v3 target that has more flash.

ROMFS/CMakeLists.txt

@@ -103,6 +103,15 @@ if (config_io_board)
 		)
 endif()
 
+if (config_bl_file)
+	file(MAKE_DIRECTORY ${PX4_BINARY_DIR}/romfs_extras)
+	configure_file(${config_bl_file} ${PX4_BINARY_DIR}/romfs_extras COPYONLY)
+
+	list(APPEND extras_dependencies
+		${config_bl_file}
+		)
+endif()
+
 add_custom_command(OUTPUT romfs_extras.stamp
 	COMMAND ${CMAKE_COMMAND} -E make_directory ${romfs_gen_root_dir}/extras/
 	COMMAND ${CMAKE_COMMAND} -E make_directory ${PX4_BINARY_DIR}/romfs_extras/

ROMFS/px4fmu_common/extras/README.txt

@@ -0,0 +1,5 @@
+px4fmuv3_bl.bin: Bootloader binary of the PX4 Bootloader
+  (https://github.com/PX4/Bootloader)
+  based on commit 184b813699a9cfd6f43a5a21556a06b4372baf5f
+  for the target px4fmuv3_bl
+

ROMFS/px4fmu_common/init.d/rcS

@@ -211,6 +211,27 @@ else
 		param reset
 	fi
 
+	#
+	# Bootloader upgrade
+	#
+	if ver hwcmp PX4FMU_V2
+	then
+		set BL_FILE /etc/extras/px4fmuv3_bl.bin
+		if [ -f $BL_FILE ]
+		then
+			if param compare SYS_BL_UPDATE 1
+			then
+				param set SYS_BL_UPDATE 0
+				param save
+				echo "BL update..." >> $LOG_FILE
+				bl_update $BL_FILE
+				echo "BL update done" >> $LOG_FILE
+				reboot
+			fi
+		fi
+		unset BL_FILE
+	fi
+
 	#
 	# Start system state indicator.
 	#