Allow style checking of tree and local changes

New phony Makefile targets have been added:

 * checkcodebase
 * checkpatch

The checkcodebase target will run a Linux style compliance check over the
entire codebase, and honours the V=1 Makefile verbose setting and so will
show more information when this is enabled.

If the local directory is a git checkout then the output of git ls-files is
used to decide which files to test for compliance.  If the local directory
is not under git control then a 'best attempt' is made, but in this case it
should be noted that it is possible for additional non-codebase files to be
tested, so care should be taken when parsing the output.

The checkpatch target will compare local changes against the git origin/master
to allow issues with the last set of changes to be identified.  To override
the change comparision location, set the BASE_COMMIT variable to your
desired git branch.

Both targets rely on the Linux source tree script checkpatch.pl to do the
syntax checking, and e...

Makefile

@@ -36,8 +36,12 @@ else
   KBUILD_VERBOSE = 0
 endif
 
+CHECKPATCH_ARGS		=	--no-tree --no-signoff
+CHECKCODE_ARGS		=	--no-patch --no-tree --no-signoff
+
 ifeq "${KBUILD_VERBOSE}" "0"
 	Q=@
+	CHECKCODE_ARGS	+=	--no-summary --terse
 else
 	Q=
 endif
@@ -102,7 +106,7 @@ ifneq (${PLAT},all)
   include bl31/bl31.mk
 endif
 
-.PHONY:			all msg_start ${PLATFORMS} dump clean realclean distclean bl1 bl2 bl31 cscope
+.PHONY:			all msg_start ${PLATFORMS} dump clean realclean distclean bl1 bl2 bl31 cscope locate-checkpatch checkcodebase checkpatch
 .SUFFIXES:
 
 
@@ -167,11 +171,23 @@ bl1:			${BUILD_BL1} ${BUILD_PLAT}/bl1.bin
 bl2:			${BUILD_BL2} ${BUILD_PLAT}/bl2.bin
 bl31:			${BUILD_BL31} ${BUILD_PLAT}/bl31.bin
 
+BASE_COMMIT		?=	origin/master
+
 ifeq (${PLAT},all)
   ifeq (${MAKECMDGOALS},clean)
     $(error "Please select a platform with PLAT=<platform>. You can use 'make distclean' to clean up all platform builds")
   endif
 endif
+
+locate-checkpatch:
+ifndef CHECKPATCH
+	$(error "Please set CHECKPATCH to point to the Linux checkpatch.pl file, eg: CHECKPATCH=../linux/script/checkpatch.pl")
+else
+ifeq (,$(wildcard ${CHECKPATCH}))
+	$(error "The file CHECKPATCH points to cannot be found, use eg: CHECKPATCH=../linux/script/checkpatch.pl")
+endif
+endif
+
 clean:
 			@echo "  CLEAN"
 			${Q}rm -rf ${BUILD_PLAT}
@@ -187,6 +203,18 @@ dump:
 			${Q}${OD} -d ${BUILD_BL2}/bl2.elf > ${BUILD_BL2}/bl2.dump
 			${Q}${OD} -d ${BUILD_BL31}/bl31.elf > ${BUILD_BL31}/bl31.dump
 
+checkcodebase:		locate-checkpatch
+			@echo "  CHECKING STYLE"
+			@if test -d .git ; then	\
+				git ls-files | while read GIT_FILE ; do ${CHECKPATCH} ${CHECKCODE_ARGS} -f $$GIT_FILE ; done ;	\
+			 else			\
+				 find . -type f -not -iwholename "*.git*" -not -iwholename "*build*" -exec ${CHECKPATCH} ${CHECKCODE_ARGS} -f {} \; ;	\
+			 fi
+
+checkpatch:		locate-checkpatch
+			@echo "  CHECKING STYLE"
+			@git format-patch --stdout ${BASE_COMMIT} | ${CHECKPATCH} ${CHECKPATCH_ARGS} - || true
+
 ${BUILD_DIRS}:
 			${Q}mkdir -p "$@"
 
@@ -267,19 +295,22 @@ cscope:
 	${Q}cscope -b -q -k
 
 help:
-	@echo "usage: ${MAKE} PLAT=<all|${HELP_PLATFORMS}> <all|bl1|bl2|bl31|distclean|clean|dump>"
+	@echo "usage: ${MAKE} PLAT=<all|${HELP_PLATFORMS}> <all|bl1|bl2|bl31|distclean|clean|checkcodebase|checkpatch|dump>"
 	@echo ""
 	@echo "PLAT is used to specify which platform you wish to build."
 	@echo ""
 	@echo "Supported Targets:"
-	@echo "  all        build the BL1, BL2 and BL31 binaries"
-	@echo "  bl1        build the BL1 binary"
-	@echo "  bl2        build the BL2 binary"
-	@echo "  bl31       build the BL31 binary"
-	@echo "  clean      Clean the build for the selected platform"
+	@echo "  all            Build the BL1, BL2 and BL31 binaries"
+	@echo "  bl1            Build the BL1 binary"
+	@echo "  bl2            Build the BL2 binary"
+	@echo "  bl31           Build the BL31 binary"
+	@echo "  checkcodebase  Check the coding style of the entire source tree"
+	@echo "  checkpatch     Check the coding style on changes in the current"
+	@echo "                 branch against BASE_COMMIT (default origin/master)"
+	@echo "  clean          Clean the build for the selected platform"
 	@echo "  cscope     Generate cscope index"
-	@echo "  distclean  Remove all build artifacts for all platforms"
-	@echo "  dump       Generate object file dumps"
+	@echo "  distclean      Remove all build artifacts for all platforms"
+	@echo "  dump           Generate object file dumps"
 	@echo ""
 	@echo "note: most build targets require PLAT to be set to a specific platform."
 	@echo ""

contributing.md

@@ -46,8 +46,11 @@ Making Changes
 
 *   Make commits of logical units. See these general [Git guidelines] for
     contributing to a project.
-*   Follow the [Linux coding style]; this style is re-used for the ARM Trusted
-    Firmware project.
+*   Follow the [Linux coding style]; this style is enforced for the ARM Trusted
+    Firmware project (style errors only, not warnings).
+    *   Use the checkpatch.pl script provided with the Linux source tree. A
+        Makefile target is provided for convenience (see section 2 in the
+        [User Guide]).
 *   Keep the commits on topic. If you need to fix another bug or make another
     enhancement, please create a separate [issue] and address it on a separate
     topic branch.

docs/user-guide.md

@@ -141,6 +141,29 @@ Extra debug options can be passed to the build system by setting `CFLAGS`:
 NOTE: The Foundation FVP does not provide a debugger interface.
 
 
+#### Checking source code style
+
+When making changes to the source for submission to the project, the source
+must be in compliance with the Linux style guide, and to assist with this check
+the project Makefile contains two targets, which both utilise the checkpatch.pl
+script that ships with the Linux source tree.
+
+To check the entire source tree, you must first download a copy of checkpatch.pl
+(or the full Linux source), set the CHECKPATCH environment variable to point to
+the script and build the target checkcodebase:
+
+    make CHECKPATCH=../linux/scripts/checkpatch.pl checkcodebase
+
+To just check the style on the files that differ between your local branch and
+the remote master, use:
+
+    make CHECKPATCH=../linux/scripts/checkpatch.pl checkpatch
+
+If you wish to check your patch against something other than the remote master,
+set the BASE_COMMIT variable to your desired branch.  By default, BASE_COMMIT
+is set to 'origin/master'.
+
+
 ### Obtaining the normal world software
 
 #### Obtaining UEFI