diff options
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 23 | ||||
| -rw-r--r-- | scripts/Makefile.lib | 10 |
2 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 14c3f4f1b617..5198b742fde1 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 bdf42fdf64c9..7910229ec665 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -269,6 +269,16 @@ 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) -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 # --------------------------------------------------------------------------- |