pflash: Clean up makefiles and resolve build race

The pflash build process has regressed from when the were last fixed in
6c21c4ffaf82.

This patch resolves that issue and performs some cleanups:

 - Remove duplicated rules. Patches had moved rules into common files,
   but forgotten to remove them from the pflash makefiles.

 - Make assignements simply expanded variables where possible. Form the
   make manual:

     Functions referenced in the definition will be executed every time
     the variable is expanded.  This makes make run slower; worse, it
     causes the wildcard and shell functions to give unpredictable
     results because you cannot easily control when they are called, or
     even how many times.

     To avoid all the problems and inconveniences of recursively
     expanded variables, there is another flavor: simply expanded
     variables.

 - set the 'shared' target as a dependency of the libflash objects. This
   was the final piece to resolve the race condition.

The failed build could be reproduced by doing a `git clean -f -x` and
then running the following:

  $ make -j 32 CROSS_COMPILE=arm-linux-gnueabi- SKIBOOT_VERSION=5.2.4
  PFLASH_VERSION=5.2.4 V=1 -C external/pflash all LINKAGE=dynamic
  make: Entering directory '/home/joel/dev/skiboot/external/pflash'
  ln -sf ../../libflash ./libflash
  ln -sf ../../ccan ./ccan
  ln -sf ../common ./common
  cc -O2 -Wall -I. -c pflash.c -o pflash.o
  cc -O2 -Wall -I. -c progress.c -o progress.o
  make -C ../shared
  make[1]: Entering directory '/home/joel/dev/skiboot/external/shared'
  ln -sf ../../hw/ast-bmc/ast-sf-ctrl.c common/ast-sf-ctrl.c
  ln -sf ../../include/ast.h common/ast.h
  ln -sf arch_flash_arm_io.h common/io.h
  cc -O2 -Wall -I.  -c common/arch_flash_common.c -o
  common-arch_flash_common.o
  cc -O2 -Wall -I.  -c common/arch_flash_arm.c -o common-arch_flash_arm.o
  cc -O2 -Wall -I.  -c common/ast-sf-ctrl.c -o common-ast-sf-ctrl.o
  cc -O2 -Wall -I. -c version.c -o version.o
  ld -r common-arch_flash_common.o common-arch_flash_arm.o
  common-ast-sf-ctrl.o -o common-arch_flash.o
  ln -sf ../../libflash ./libflash
  ln -sf ../../ccan ./ccan
  ln -sf ../common ./common
  make[1]: *** No rule to make target 'libflash/file.c', needed by
  'libflash-file.o'.  Stop.
  make[1]: *** Waiting for unfinished jobs....
  make[1]: Leaving directory '/home/joel/dev/skiboot/external/shared'
  rules.mk:25: recipe for target
  '../shared/libflash.so.skiboot-5.2.4-1-g9f13f64c322f-joel-dirty-d5873ce'
  failed
  make: ***
  [../shared/libflash.so.skiboot-5.2.4-1-g9f13f64c322f-joel-dirty-d5873ce]
  Error 2

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
(cherry picked from commit c327eddd9b291a0e6e54001fa3b1e547bad3fca2)
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

3 files changed, 20 insertions, 21 deletions

diff --git a/external/pflash/Makefile b/external/pflash/Makefile
index 3a4c563..4c9b08b 100644
--- a/external/pflash/Makefile
+++ b/external/pflash/Makefile
@@ -1,5 +1,5 @@
 include rules.mk
-GET_ARCH = ../../external/common/get_arch.sh
+GET_ARCH := ../../external/common/get_arch.sh
 include ../../external/common/rules.mk
 
 all: links arch_links $(EXE)
diff --git a/external/pflash/rules.mk b/external/pflash/rules.mk
index df814fe..6be9b67 100644
--- a/external/pflash/rules.mk
+++ b/external/pflash/rules.mk
@@ -1,11 +1,8 @@
 .DEFAULT_GOAL := all
 
 override CFLAGS  += -O2 -Wall -I.
-PFLASH_OBJS    = pflash.o progress.o version.o common-arch_flash.o
-LIBFLASH_FILES := libflash.c libffs.c ecc.c blocklevel.c file.c
-LIBFLASH_OBJS := $(addprefix libflash-, $(LIBFLASH_FILES:.c=.o))
-LIBFLASH_SRC := $(addprefix libflash/,$(LIBFLASH_FILES))
-OBJS	= $(PFLASH_OBJS) $(LIBFLASH_OBJS)
+PFLASH_OBJS    := pflash.o progress.o version.o common-arch_flash.o
+OBJS	:= $(PFLASH_OBJS) $(LIBFLASH_OBJS)
 EXE     = pflash
 sbindir?=/usr/sbin
 
@@ -14,8 +11,8 @@ LINKAGE?=static
 
 ifeq ($(LINKAGE),dynamic)
 include ../shared/rules.mk
-SHARED=../shared/$(SHARED_NAME)
-OBJS=$(PFLASH_OBJS) $(SHARED)
+SHARED	:= ../shared/$(SHARED_NAME)
+OBJS	:= $(PFLASH_OBJS) $(SHARED)
 INSTALLDEPS+=install-shared
 
 install-shared:
@@ -35,11 +32,6 @@ version.c: .version
 %.o : %.c
 	$(Q_CC)$(CC) $(CFLAGS) -c $< -o $@
 
-$(LIBFLASH_SRC): | links
-
-$(LIBFLASH_OBJS): libflash-%.o : libflash/%.c
-	$(Q_CC)$(CC) $(CFLAGS) -c $< -o $@
-
 $(EXE): $(OBJS)
 	$(Q_CC)$(CC) $(CFLAGS) $^ -lrt -o $@
 
diff --git a/external/shared/Makefile b/external/shared/Makefile
index c643666..e0b3ff3 100644
--- a/external/shared/Makefile
+++ b/external/shared/Makefile
@@ -1,23 +1,30 @@
 .DEFAULT_GOAL := all
-GET_ARCH = ../../external/common/get_arch.sh
+GET_ARCH := ../../external/common/get_arch.sh
 include ../../external/common/rules.mk
 include rules.mk
 
 PREFIX ?= /usr/local/
-LIBDIR = $(PREFIX)/lib
-INCDIR = $(PREFIX)/include/libflash
+LIBDIR := $(PREFIX)/lib
+INCDIR := $(PREFIX)/include/libflash
 
 ifneq ($(ARCH), ARCH_ARM)
 CFLAGS += -m64
 endif
 CFLAGS += -Werror -Wall -g2 -ggdb -I. -fPIC
 
-LIBFLASH_OBJS = libflash-file.o libflash-libflash.o libflash-libffs.o libflash-ecc.o libflash-blocklevel.o
-ARCHFLASH_OBJS = common-arch_flash.o
-OBJS = $(LIBFLASH_OBJS) $(ARCHFLASH_OBJS)
+LIBFLASH_OBJS := libflash-file.o libflash-libflash.o libflash-libffs.o \
+	libflash-ecc.o libflash-blocklevel.o
+ARCHFLASH_OBJS := common-arch_flash.o
+OBJS := $(LIBFLASH_OBJS) $(ARCHFLASH_OBJS)
 
-LIBFLASH_H = libflash/file.h libflash/libflash.h libflash/libffs.h libflash/ffs.h libflash/ecc.h libflash/blocklevel.h libflash/errors.h
-ARCHFLASH_H = common/arch_flash.h
+LIBFLASH_H := libflash/file.h libflash/libflash.h libflash/libffs.h \
+	libflash/ffs.h libflash/ecc.h libflash/blocklevel.h libflash/errors.h
+ARCHFLASH_H := common/arch_flash.h
+
+LIBFLASH_FILES := libflash.c libffs.c ecc.c blocklevel.c file.c
+LIBFLASH_SRC := $(addprefix libflash/,$(LIBFLASH_FILES))
+
+$(LIBFLASH_SRC): | links
 
 $(LIBFLASH_OBJS) : libflash-%.o : libflash/%.c
 	$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@