binman: Add option for pointing to separate description

Adding binman node with target images description can be unwanted feature
but as of today there is no way to disable it.
Also on size constrained systems it is not useful to add binman description
to DTB.
Introduce BINMAN_DTB Kconfig symbol which allows separate DTB for target
from DTB for binman itself.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/f1379d2587f9bf279a7a75c318aabbc1b35ee0c6.1730452668.git.michal.simek@amd.com

Makefile

@@ -1392,12 +1392,21 @@ endif
 default_dt := $(if $(DEVICE_TREE),$(DEVICE_TREE),$(CONFIG_DEFAULT_DEVICE_TREE))
 endif
 
+binman_dtb := $(shell echo $(CONFIG_BINMAN_DTB))
+ifeq ($(strip $(binman_dtb)),)
+ifeq ($(CONFIG_OF_EMBED),y)
+binman_dtb = ./dts/dt.dtb
+else
+binman_dtb = ./u-boot.dtb
+endif
+endif
+
 quiet_cmd_binman = BINMAN  $@
 cmd_binman = $(srctree)/tools/binman/binman $(if $(BINMAN_DEBUG),-D) \
 		$(foreach f,$(BINMAN_TOOLPATHS),--toolpath $(f)) \
                 --toolpath $(objtree)/tools \
 		$(if $(BINMAN_VERBOSE),-v$(BINMAN_VERBOSE)) \
-		build -u -d u-boot.dtb -O . -m \
+		build -u -d $(binman_dtb) -O . -m \
 		--allow-missing --fake-ext-blobs \
 		$(if $(BINMAN_ALLOW_MISSING),--ignore-missing) \
 		-I . -I $(srctree) -I $(srctree)/board/$(BOARDDIR) \

lib/Kconfig

@@ -45,6 +45,15 @@ config BINMAN_FDT
 	  locate entries in the firmware image. See binman.h for the available
 	  functionality.
 
+config BINMAN_DTB
+	string "binman DTB description"
+	depends on BINMAN
+	help
+	  This enables option to point to different DTB file with binman node which
+	  is outside of DTB used by the firmware. Use this option if information
+	  about generated images shouldn't be the part of target binary. Or on system
+	  with limited storage.
+
 config CC_OPTIMIZE_LIBS_FOR_SPEED
 	bool "Optimize libraries for speed"
 	help