barebox: Allow to build an environment image

[Peter: Tweaked help text]
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

boot/barebox/Config.in

@@ -99,4 +99,23 @@ config BR2_TARGET_BAREBOX_BAREBOXENV
 	help
 	  Install bareboxenv tool in target.
 
+config BR2_TARGET_BAREBOX_CUSTOM_ENV
+	bool "Generate an environment image"
+	help
+	  Generate a custom environment image. This environment will
+	  contain the variables and scripts to be used at boot by
+	  barebox.
+
+config BR2_TARGET_BAREBOX_CUSTOM_ENV_PATH
+	string "Environment path"
+	depends on BR2_TARGET_BAREBOX_CUSTOM_ENV
+	help
+	  Path to the directory containing the custom barebox
+	  environment. Depending on your setup, it will probably be
+	  based on either the content of the defaultenv or
+	  defaultenv-2 directories in the barebox source code, plus
+	  the additions needed. The output will be an image in the
+	  barebox devfs format, stored in the images directory, with
+	  the same name as the directory name given here.
+
 endif

boot/barebox/barebox.mk

@@ -67,9 +67,22 @@ define BAREBOX_BUILD_BAREBOXENV_CMDS
 endef
 endif
 
+ifeq ($(BR2_TARGET_BAREBOX_CUSTOM_ENV),y)
+BAREBOX_ENV_NAME = $(notdir $(call qstrip, $(BR2_TARGET_BAREBOX_CUSTOM_ENV_PATH)))
+define BAREBOX_BUILD_CUSTOM_ENV
+	$(@D)/scripts/bareboxenv -s \
+		$(call qstrip, $(BR2_TARGET_BAREBOX_CUSTOM_ENV_PATH)) \
+		$(@D)/$(BAREBOX_ENV_NAME)
+endef
+define BAREBOX_INSTALL_CUSTOM_ENV
+	cp $(@D)/$(BAREBOX_ENV_NAME) $(BINARIES_DIR)
+endef
+endif
+
 define BAREBOX_BUILD_CMDS
 	$(BAREBOX_BUILD_BAREBOXENV_CMDS)
 	$(TARGET_MAKE_ENV) $(MAKE) $(BAREBOX_MAKE_FLAGS) -C $(@D)
+	$(BAREBOX_BUILD_CUSTOM_ENV)
 endef
 
 define BAREBOX_INSTALL_IMAGES_CMDS
@@ -78,6 +91,7 @@ define BAREBOX_INSTALL_IMAGES_CMDS
 	else \
 		cp $(@D)/barebox.bin $(BINARIES_DIR);\
 	fi
+	$(BAREBOX_INSTALL_CUSTOM_ENV)
 endef
 
 ifeq ($(BR2_TARGET_BAREBOX_BAREBOXENV),y)