build: make Poetry optional

The Yocto team has requested that we do not use Poetry from within the
Makefile, as Yocto does not have network access during the build
process.

We want to maintain the current behaviour, so this change makes our use
of Poetry contigent on it being available in the environment.

Additionally, explicitly passing an empty toolchain parameter now allows
a tool to be *disabled* (e.g. passing `POETRY=` will prevent the build
system from trying to use Poetry).

Change-Id: Ibf552a3fee1eaadee767a1b948b559700083b401
Signed-off-by: Chris Kay <chris.kay@arm.com>

Makefile

@@ -1733,8 +1733,8 @@ endif
 
 tl: ${BUILD_PLAT}/tl.bin
 ${BUILD_PLAT}/tl.bin: ${HW_CONFIG}
-	$(q)poetry -q install
+	$(if $(host-poetry),$(q)poetry -q install)
-	$(q)poetry run tlc create --fdt $< -s ${FW_HANDOFF_SIZE} $@
+	$(q)$(if $(host-poetry),poetry run )tlc create --fdt $< -s ${FW_HANDOFF_SIZE} $@
 
 doc:
 	$(s)echo "  BUILD DOCUMENTATION"

make_helpers/toolchain.mk

@@ -118,6 +118,9 @@ ifndef toolchain-mk
         toolchain-tool-classes += dtc
         toolchain-tool-class-name-dtc := device tree compiler
 
+        toolchain-tool-classes += poetry
+        toolchain-tool-class-name-poetry := Python Poetry package manager
+
         #
         # Configure tools that we recognize.
         #
@@ -175,6 +178,9 @@ ifndef toolchain-mk
         toolchain-tools += generic-dtc
         toolchain-tool-name-generic-dtc := Device Tree Compiler (`dtc`)
 
+        toolchain-tools += generic-poetry
+        toolchain-tool-name-generic-poetry := Poetry (`poetry`)
+
         #
         # Assign tools to tool classes.
         #
@@ -199,6 +205,7 @@ ifndef toolchain-mk
 
         # Other tools
         toolchain-tools-dtc := generic-dtc # Device tree compilers
+        toolchain-tools-poetry := generic-poetry # Python Poetry package manager
 
         #
         # Helper functions to identify toolchain tools.
@@ -256,9 +263,10 @@ ifndef toolchain-mk
 
         # Other tools
         toolchain-guess-tool-generic-dtc = $(shell $(1) --version 2>&1 <$(nul) | grep -o "Version: DTC")
+        toolchain-guess-tool-generic-poetry = $(shell $(1) --version 2>&1 <$(nul))
 
-        toolchain-guess-tool = $(firstword $(foreach candidate,$(1), \
+        toolchain-guess-tool = $(if $(2),$(firstword $(foreach candidate,$(1),$\
-                $(if $(call toolchain-guess-tool-$(candidate),$(2)),$(candidate))))
+                $(if $(call toolchain-guess-tool-$(candidate),$(2)),$(candidate)))))
 
         #
         # Warn the user that a tool could not be identified.
@@ -313,26 +321,28 @@ ifndef toolchain-mk
         # toolchain.
         #
 
-        toolchain-guess-arm-clang-cpp = $(1)
+        toolchain-derive-arm-clang-cpp = $(1)
-        toolchain-guess-arm-clang-as = $(1)
+        toolchain-derive-arm-clang-as = $(1)
-        toolchain-guess-arm-clang-ld = # Fall back to `$(toolchain)-ld-default`
+        toolchain-derive-arm-clang-ld = # Fall back to `$(toolchain)-ld-default`
-        toolchain-guess-arm-clang-oc = # Fall back to `$(toolchain)-oc-default`
+        toolchain-derive-arm-clang-oc = # Fall back to `$(toolchain)-oc-default`
-        toolchain-guess-arm-clang-od = # Fall back to `$(toolchain)-od-default`
+        toolchain-derive-arm-clang-od = # Fall back to `$(toolchain)-od-default`
-        toolchain-guess-arm-clang-ar = # Fall back to `$(toolchain)-ar-default`
+        toolchain-derive-arm-clang-ar = # Fall back to `$(toolchain)-ar-default`
 
-        toolchain-guess-llvm-clang-cpp = $(1)
+        toolchain-derive-llvm-clang-cpp = $(1)
-        toolchain-guess-llvm-clang-as = $(1)
+        toolchain-derive-llvm-clang-as = $(1)
-        toolchain-guess-llvm-clang-ld = $(shell $(1) --print-prog-name ld.lld 2>$(nul))
+        toolchain-derive-llvm-clang-ld = $(shell $(1) --print-prog-name ld.lld 2>$(nul))
-        toolchain-guess-llvm-clang-oc = $(shell $(1) --print-prog-name llvm-objcopy 2>$(nul))
+        toolchain-derive-llvm-clang-oc = $(shell $(1) --print-prog-name llvm-objcopy 2>$(nul))
-        toolchain-guess-llvm-clang-od = $(shell $(1) --print-prog-name llvm-objdump 2>$(nul))
+        toolchain-derive-llvm-clang-od = $(shell $(1) --print-prog-name llvm-objdump 2>$(nul))
-        toolchain-guess-llvm-clang-ar = $(shell $(1) --print-prog-name llvm-ar 2>$(nul))
+        toolchain-derive-llvm-clang-ar = $(shell $(1) --print-prog-name llvm-ar 2>$(nul))
 
-        toolchain-guess-gnu-gcc-cpp = $(1)
+        toolchain-derive-gnu-gcc-cpp = $(1)
-        toolchain-guess-gnu-gcc-as = $(1)
+        toolchain-derive-gnu-gcc-as = $(1)
-        toolchain-guess-gnu-gcc-ld = $(1)
+        toolchain-derive-gnu-gcc-ld = $(1)
-        toolchain-guess-gnu-gcc-oc = $(shell $(1) --print-prog-name objcopy 2>$(nul))
+        toolchain-derive-gnu-gcc-oc = $(shell $(1) --print-prog-name objcopy 2>$(nul))
-        toolchain-guess-gnu-gcc-od = $(shell $(1) --print-prog-name objdump 2>$(nul))
+        toolchain-derive-gnu-gcc-od = $(shell $(1) --print-prog-name objdump 2>$(nul))
-        toolchain-guess-gnu-gcc-ar = $(shell $(1) --print-prog-name ar 2>$(nul))
+        toolchain-derive-gnu-gcc-ar = $(shell $(1) --print-prog-name ar 2>$(nul))
+
+        toolchain-derive = $(if $3,$(call toolchain-derive-$1-$2,$3))
 
         #
         # Configure a toolchain.
@@ -393,25 +403,32 @@ ifndef toolchain-mk
         #
 
         define toolchain-determine-tool
-                toolchain-$1-$2-guess-from-cc = $$(if $$(filter-out cc,$2),$\
+                toolchain-$1-$2-derive-from-cc = $$(if $$(filter-out cc,$2),$\
-                        $$(call toolchain-guess-$$($1-cc-id)-$2,$$($1-cc)))
+                        $$(call toolchain-derive,$$($1-cc-id),$2,$$($1-cc)))
 
-                toolchain-$1-$2-shell = $$(or $$($$($1-$2-parameter)),$\
+                toolchain-$1-$2-shell = $\
-                        $$(toolchain-$1-$2-guess-from-cc),$\
+                        $$(if $$(call defined,$$($1-$2-parameter)),$\
-                        $$(toolchain-$1-$2-default))
+                                $$($$($1-$2-parameter)),$\
+                                $$(or $$(toolchain-$1-$2-derive-from-cc),$\
+                                        $$(toolchain-$1-$2-default)))
 
                 toolchain-$1-$2-default = $$(firstword $\
                         $$(foreach default,$$($1-$2-default),$\
                                 $$(if $$(call which,$$(default)),$$(default))) $\
                         $$($1-$2-default))
 
-                $1-$2 := $(if $(call which,$$(toolchain-$1-$2-shell)),$\
+                $1-$2 := $$(if $$(call which,$$(toolchain-$1-$2-shell)),$\
                         $$(call escape-shell,$$(toolchain-$1-$2-shell)),$\
                         $$(toolchain-$1-$2-shell))
 
-                $1-$2-id := $$(or \
+                $1-$2-id := $$(if $$($1-$2),$$(or $\
-                        $$(call toolchain-guess-tool,$$(toolchain-tools-$2),$$($1-$2)),$\
+                        $$(call toolchain-guess-tool,$$\
-                        $$(strip $$(call toolchain-warn-unrecognized,$1,$2)$$($1-$2-default-id)))
+                                $$(toolchain-tools-$2),$$($1-$2)),$\
+                        $$($1-$2-default-id)))
+
+                ifeq ($$(or $$($1-$2-id),$$(call bool,$$($1-$2-optional))),)
+                        $$(call toolchain-warn-unrecognized,$1,$2)
+                endif
         endef
 
         $(foreach toolchain,$(toolchains), \

make_helpers/toolchains/host.mk

@@ -37,3 +37,8 @@ host-ar-default := gcc-ar
 host-dtc-parameter := HOSTDTC
 host-dtc-default-id := generic-dtc
 host-dtc-default := dtc
+
+host-poetry-parameter := POETRY
+host-poetry-optional := yes
+host-poetry-default-id := generic-poetry
+host-poetry-default := poetry

make_helpers/utilities.mk

@@ -100,3 +100,23 @@ bool = $(filter-out 0 n no f false,$(call lowercase,$(1)))
 #
 
 bool-01 = $(if $(call bool,$(1)),1,0)
+
+#
+# Determine whether a variable is defined or not.
+#
+# Parameters:
+#
+#   - $(1): The variable to check.
+#
+# Example usage:
+#
+#     xyz-defined := $(call defined,xyz) # <empty>
+#
+#     xyz :=
+#     xyz-defined := $(call defined,xyz) # <non-empty>
+#
+#     xyz := hello
+#     xyz-defined := $(call defined,xyz) # <non-empty>
+#
+
+defined = $(call bool,$(filter-out undefined,$(origin $(1))))

plat/arm/common/arm_common.mk

@@ -484,8 +484,8 @@ ifneq ($(COTDTPATH),)
 		$(q)$($(ARCH)-cpp) $(cot-dt-cpp-flags)
 
         $(BUILD_PLAT)/$(COTDTPATH:.dtsi=.c): $(BUILD_PLAT)/$(COTDTPATH:.dtsi=.dts) | $$(@D)/
-		$(q)poetry -q install
+		$(if $(host-poetry),$(q)poetry -q install)
-		$(q)poetry run cot-dt2c convert-to-c $< $@
+		$(q)$(if $(host-poetry),poetry run )cot-dt2c convert-to-c $< $@
 
         BL2_SOURCES += $(BUILD_PLAT)/$(COTDTPATH:.dtsi=.c)
 endif