[PATCH v4] arm: Add Kconfig entry to select CONFIG_DTB_FILE

[Michal Orzel <michal.orzel@xxxxxxx>]

Currently in order to link existing DTB into Xen image
we need to either specify option CONFIG_DTB_FILE on the
command line or manually add it into .config.
Add Kconfig entry: CONFIG_DTB_FILE to be able to
provide the path to DTB we want to embed into Xen image.
If no path provided - the dtb will not be embedded.

Remove the line: AFLAGS-y += -DCONFIG_DTB_FILE=\"$(CONFIG_DTB_FILE)\"
as it is not needed since Kconfig will define it in a header
with all the other config options.

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/arch/arm/Makefile | 5 ++---
 xen/common/Kconfig    | 8 ++++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 16e6523e2c..46e6a95fec 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -68,9 +68,8 @@ extra-y += $(TARGET_SUBARCH)/head.o
 
 #obj-bin-y += ....o
 
-ifdef CONFIG_DTB_FILE
+ifneq ($(CONFIG_DTB_FILE),"")
 obj-y += dtb.o
-AFLAGS-y += -DCONFIG_DTB_FILE=\"$(CONFIG_DTB_FILE)\"
 endif
 
 ALL_OBJS := $(TARGET_SUBARCH)/head.o $(ALL_OBJS)
@@ -137,7 +136,7 @@ asm-offsets.s: $(TARGET_SUBARCH)/asm-offsets.c
 xen.lds: xen.lds.S
        $(CPP) -P $(a_flags) -MQ $@ -o $@ $<
 
-dtb.o: $(CONFIG_DTB_FILE)
+dtb.o: $(patsubst "%",%,$(CONFIG_DTB_FILE))
 
 .PHONY: clean
 clean::
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index eb953d171e..a27836bf47 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -400,6 +400,14 @@ config DOM0_MEM
 
          Leave empty if you are not sure what to specify.
 
+config DTB_FILE
+       string "Absolute path to device tree blob"
+       depends on HAS_DEVICE_TREE
+       ---help---
+         When using a bootloader that has no device tree support or when there
+         is no bootloader at all, use this option to specify the absolute path
+         to a device tree that will be linked directly inside Xen binary.
+
 config TRACEBUFFER
        bool "Enable tracing infrastructure" if EXPERT
        default y
-- 
2.29.0