Commit 22435f38 authored by Stephen Warren's avatar Stephen Warren Committed by Grant Likely

kbuild: create a rule to run the pre-processor on *.dts files

Create cmd_dtc_cpp to run the C pre-processor on *.dts file before
passing them to dtc for final compilation. This allows the use of #define
and #include within the .dts file.
Acked-by: default avatarSimon Glass <sjg@chromium.org>
Acked-by: default avatarJean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: default avatarMichal Marek <mmarek@suse.cz>
Acked-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 1d0b1c74
...@@ -1186,6 +1186,29 @@ When kbuild executes, the following steps are followed (roughly): ...@@ -1186,6 +1186,29 @@ When kbuild executes, the following steps are followed (roughly):
clean-files += *.dtb clean-files += *.dtb
DTC_FLAGS ?= -p 1024 DTC_FLAGS ?= -p 1024
dtc_cpp
This is just like dtc as describe above, except that the C pre-
processor is invoked upon the .dtsp file before compiling the result
with dtc.
In order for build dependencies to work, all files compiled using
dtc_cpp must use the C pre-processor's #include functionality and not
dtc's /include/ functionality.
Using the C pre-processor allows use of #define to create named
constants. In turn, the #defines will typically appear in a header
file, which may be shared with regular C code. Since the dtc language
represents a data structure rather than code in C syntax, similar
restrictions are placed on a header file included by a device tree
file as for a header file included by an assembly language file.
In particular, the C pre-processor is passed -x assembler-with-cpp,
which sets macro __ASSEMBLY__. __DTS__ is also set. These allow header
files to restrict their content to that compatible with device tree
source.
A central rule exists to create $(obj)/%.dtb from $(src)/%.dtsp;
architecture Makefiles do no need to explicitly write out that rule.
--- 6.8 Custom kbuild commands --- 6.8 Custom kbuild commands
When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand
......
...@@ -269,6 +269,16 @@ cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile ...@@ -269,6 +269,16 @@ cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) -d $(depfile
$(obj)/%.dtb: $(src)/%.dts FORCE $(obj)/%.dtb: $(src)/%.dts FORCE
$(call if_changed_dep,dtc) $(call if_changed_dep,dtc)
dtc-tmp = $(subst $(comma),_,$(dot-target).dts)
quiet_cmd_dtc_cpp = DTC+CPP $@
cmd_dtc_cpp = $(CPP) $(cpp_flags) -x assembler-with-cpp -undef -D__DTS__ \
-o $(dtc-tmp) $< ; \
$(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 $(DTC_FLAGS) $(dtc-tmp)
$(obj)/%.dtb: $(src)/%.dtsp FORCE
$(call if_changed_dep,dtc_cpp)
# Bzip2 # Bzip2
# --------------------------------------------------------------------------- # ---------------------------------------------------------------------------
......
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