On 11:43 Wed 02 Jan , Stephen Warren wrote: > From: Stephen Warren <swar...@nvidia.com> > > 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. > > Signed-off-by: Stephen Warren <swar...@nvidia.com> Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagn...@jcrosoft.com>
Best Regards, J. > --- > Grant, back in mid-November, you said you'd make a decision on this in > the next couple of days, but I think this got overlooked. > > v7: Build *.dtb from *.dts not src/*.dts. > v6: No change. > v5: > * Update Documentation/kbuild for the new command and rule. > v4: > * Use -x assembler-with-cpp so pre-defined macros are set up so that > #included header files know to only use cpp syntax, not C syntax. > * Define __DTS__ for similar reasons. > * use $(CPP) not $(CC) -E, and use $(cpp_flags). > * Save the pre-processed results so they can be easily inspected when > debugging build issues. > * The use of -x assembler-with-cpp causes cpp to recognize directives in > column 1 only. Hence, there's no need to escape property names that > begin with #. Hence, there's no need for separate skeleton.dtsi and > skeleton.dtsip. Maintain a separate file extension and build rule so that > CPP-usage is opt-in. In particular, when using CPP, #include must be used > rather than /include/ so that dependencies work. > v3: Pass "-x c" not "-xc" to cpp. > v2: Place make %.dtb: %.dtsp rule into Makefile.lib. > --- > Documentation/kbuild/makefiles.txt | 23 +++++++++++++++++++++++ > scripts/Makefile.lib | 9 +++++++++ > 2 files changed, 32 insertions(+) > > diff --git a/Documentation/kbuild/makefiles.txt > b/Documentation/kbuild/makefiles.txt > index 14c3f4f..5198b74 100644 > --- a/Documentation/kbuild/makefiles.txt > +++ b/Documentation/kbuild/makefiles.txt > @@ -1186,6 +1186,29 @@ When kbuild executes, the following steps are followed > (roughly): > clean-files += *.dtb > 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 > > When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index bdf42fd..2c2a302 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -269,6 +269,15 @@ cmd_dtc = $(objtree)/scripts/dtc/dtc -O dtb -o $@ -b 0 > $(DTC_FLAGS) -d $(depfile > $(obj)/%.dtb: $(src)/%.dts FORCE > $(call if_changed_dep,dtc) > > +dtc-tmp = $(subst $(comma),_,$(dot-target).dts) > + > +quiet_cmd_dtc_cpp = DTC+CPP $@ > +cmd_dtc_cpp = $(CPP) $(cpp_flags) -D__DTS__ -x assembler-with-cpp -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 > # --------------------------------------------------------------------------- > > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
