kbuild: Allow using host dtc instead of kernel's copy

Development of dtc happens in its own upstream repository, but testing dtc changes against the kernel tree is useful. Change dtc to a variable that users can override.

Signed-off-by Rob Herring <[email protected]>

Cc Michal Marek <[email protected]>

Cc [email protected]

---
 scripts/Makefile.lib | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

scripts/Makefile.lib +2 -2

index 79e8661..ceceb53 100644
@@ -262,6 +262,7 @@ cmd_gzip = (cat $(filter-out FORCE,$^) | gzip -n -f -9 > $@) || \
 
 # DTC
 # ---------------------------------------------------------------------------
+DTC ?= $(objtree)/scripts/dtc/dtc
 
 # Generate an assembly file to wrap the output of the device tree compiler
 quiet_cmd_dt_S_dtb= DTB     $@

@@ -284,7 +285,7 @@ $(obj)/%.dtb.S: $(obj)/%.dtb
 quiet_cmd_dtc = DTC     $@
 cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
        $(CPP) $(dtc_cpp_flags) -x assembler-with-cpp -o $(dtc-tmp) $< ; \
-       $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 \
+       $(DTC) -O dtb -o $@ -b 0 \
                -i $(dir $<) $(DTC_FLAGS) \
                -d $(depfile).dtc.tmp $(dtc-tmp) ; \
        cat $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
--

2.5.0