[make] add a quick in dirty help target for the build system

make help: a quick overview of how to use the build system
make list: a list of all the buildable projects

make/help.mk

@@ -0,0 +1,53 @@
+# routines and rules to print some helpful stuff
+
+
+#$(warning MAKECMDGOALS = $(MAKECMDGOALS))
+
+# print some help and exit
+ifeq ($(firstword $(MAKECMDGOALS)),help)
+do-nothing=1
+
+.PHONY: help
+help:
+	@echo "LK build system quick help\n" \
+	"Individual projects are built into a build-<project> directory\n" \
+	"Output binary is located at build-<project>/lk.bin\n" \
+	"Environment or command line variables controlling build:\n" \
+	"PROJECT = <project name>\n" \
+	"TOOLCHAIN_PREFIX = <absolute path to toolchain or relative path with prefix>\n" \
+	"\n" \
+	"Special make targets:\n" \
+	"make help: This help\n" \
+	"make list: List of buildable projects\n" \
+	"make clean: cleans build of current project\n" \
+	"make spotless: removes all build directories\n" \
+	"make <project>: try to build project named <project>\n" \
+	"\n" \
+	"Examples:\n" \
+	"PROJECT=testproject make\n" \
+	"PROJECT=testproject make clean\n" \
+	"make testproject\n" \
+	"make testproject clean\n" \
+	"\n" \
+	"output will be in build-testproject/\n" \
+
+endif
+
+# list projects
+ifeq ($(firstword $(MAKECMDGOALS)),list)
+do-nothing=1
+
+# get a list of all the .mk files in the top level project directories
+PROJECTS:=$(basename $(strip $(foreach d,$(LKINC),$(wildcard $(d)/project/*.mk))))
+PROJECTS:=$(shell basename $(PROJECTS))
+
+.PHONY: list
+list:
+	@echo 'List of all buildable projects: (look in project/ directory)'; \
+	for p in $(PROJECTS); do \
+		echo $$p; \
+	done
+
+endif
+
+# vim: set syntax=make noexpandtab