Add basic help output

Makefile

@@ -33,4 +33,19 @@ include src/arch/${arch}/Makefile.inc
 clean: arch_clean
 	rm -f build/system.elf
 
-.PHONY: clean
+help: arch_help
+	@echo
+	@echo "Global flags:"
+	@echo "    timer_cycles timer_us timer_s"
+	@echo "    loop"
+	@echo
+	@echo "${arch} drivers:"
+	@echo "    $(shell ls src/arch/${arch}/driver | fgrep .c | cut -d . -f 1)"
+	@echo
+	@echo "Global drivers:"
+	@echo "    $(shell ls src/driver | fgrep .c | cut -d . -f 1)"
+	@echo
+	@echo "Global architectures:"
+	@echo "    $(shell ls src/arch)"
+
+.PHONY: clean help

src/arch/arduino-nano/Makefile.inc

@@ -39,4 +39,9 @@ arch_clean:
 monitor:
 	screen ${PORT} 115200
 
-.PHONY: arch_clean monitor program
+arch_help:
+	@echo "arduino-nano specific flags:"
+	@echo "    PORT = ${PORT}"
+	@echo "    BAUD = ${BAUD} (only used for programming)"
+
+.PHONY: arch_clean arch_help monitor program

src/arch/esp8266/Makefile.inc

@@ -53,4 +53,8 @@ arch_clean:
 monitor:
 	screen /dev/ttyUSB0 115200
 
-.PHONY: arch_clean monitor program
+arch_help:
+	@echo "esp8266 specific flags:"
+	@echo "    - none -"
+
+.PHONY: arch_clean arch_help monitor program

src/arch/msp430fr5969lp/Makefile.inc

@@ -42,4 +42,8 @@ arch_clean:
 monitor:
 	screen /dev/ttyACM1 115200
 
-.PHONY: arch_clean monitor program
+arch_help:
+	@echo "msp430fR5969lp specific flags:"
+	@echo "    - none -"
+
+.PHONY: arch_clean arch_help monitor program

src/arch/posix/Makefile.inc

@@ -26,4 +26,8 @@ program: run
 arch_clean:
 	rm -f ${OBJECTS}
 
-.PHONY: arch_clean monitor program run
+arch_help:
+	@echo "posix specific flags:"
+	@echo "    - none -"
+
+.PHONY: arch_clean arch_help monitor program run