build: Add support for binary modules

Change-Id: I054a77d3295150c1e5445d430cabaad978e7e594
Signed-off-by: Nicola Mazzucato <nicola.mazzucato@arm.com>

2 files changed, 63 insertions, 14 deletions

diff --git a/tools/build_system/doc.md b/tools/build_system/doc.md
index 2eee57f1..92671b26 100644
--- a/tools/build_system/doc.md
+++ b/tools/build_system/doc.md
@@ -101,11 +101,10 @@ BUILD_DISABLE_API_BAR
 Module
 ======
 
-Modules are the building blocks of a firmware product and are built as
-libraries. Modules can be implemented under the modules/ directory at the root
-of the project, or they can be product-specific and implemented under the
-product/\<product\>/modules directory. In either case, modules have the
-following directory structure:
+Modules are the building blocks of a product firmware. Modules can be
+implemented under the modules/ directory at the root of the project, or they
+can be product-specific and implemented under the product/\<product\>/modules
+directory. In either case, modules have the following directory structure:
 
     <module root>
      └── <module>
@@ -114,9 +113,17 @@ following directory structure:
           ├── src
           │    ├── Makefile
           │    └── <source files...>
+          ├── lib
+          │    └── mod_<module>.a
           └── doc
                └── <documentation files...>
 
+Only one of the 'src' or 'lib' directories is required. When building a
+firmware, if the 'src' directory is present then the module library is built
+from the module source code and the 'lib' directory, if present, is ignored.
+When only the 'lib' directory is supplied, the module's pre-built static library
+is used when building a firmware.
+
 __Note:__ The name of the \<module\> directory must not contain spaces.
 
 The name of the \<module\> directory is used in __BS_FIRMWARE_MODULES__ by the
diff --git a/tools/build_system/firmware.mk b/tools/build_system/firmware.mk
index 9ce513a9..95e2733a 100644
--- a/tools/build_system/firmware.mk
+++ b/tools/build_system/firmware.mk
@@ -109,8 +109,10 @@ SOURCES = $(BS_FIRMWARE_SOURCES)
 #
 # Modules
 #
-ALL_STANDARD_MODULES := $(shell ls $(MODULES_DIR) 2>/dev/null)
-ALL_PRODUCT_MODULES := $(shell ls $(PRODUCT_MODULES_DIR) 2>/dev/null)
+ALL_STANDARD_MODULES := $(patsubst $(MODULES_DIR)/%,%, \
+    $(wildcard $(MODULES_DIR)/*))
+ALL_PRODUCT_MODULES := $(patsubst $(PRODUCT_MODULES_DIR)/%,%, \
+    $(wildcard $(PRODUCT_MODULES_DIR)/*))
 
 # Check for conflicts between module names
 CONFLICTING_MODULES := $(filter $(ALL_PRODUCT_MODULES), $(ALL_STANDARD_MODULES))
@@ -127,11 +129,44 @@ ifneq ($(MISSING_MODULES),)
     $(error "Missing or invalid module(s): $(MISSING_MODULES). Aborting...")
 endif
 
+# Collect both the product and non product-specific module directory paths
+MODULE_PATHS := $(wildcard $(MODULES_DIR)/* $(PRODUCT_MODULES_DIR)/*)
+
+# Filter out the module src/lib directory paths
+SOURCE_MODULE_PATHS := $(wildcard $(addsuffix /src,$(MODULE_PATHS)))
+LIBRARY_MODULE_PATHS := $(wildcard $(addsuffix /lib,$(MODULE_PATHS)))
+
+# Pull the module names from the module source directory paths
+SOURCE_MODULES := \
+    $(patsubst $(MODULES_DIR)/%/src,%,$(SOURCE_MODULE_PATHS))
+SOURCE_MODULES := \
+    $(patsubst $(PRODUCT_MODULES_DIR)/%/src,%,$(SOURCE_MODULES))
+
+# Select the source modules for the current firmware
+SOURCE_MODULES := $(filter $(FIRMWARE_MODULES_LIST),$(SOURCE_MODULES))
+
+# Pull the module names from the module library directory paths
+LIBRARY_MODULES := \
+    $(patsubst $(MODULES_DIR)/%/lib,%,$(LIBRARY_MODULE_PATHS))
+LIBRARY_MODULES := \
+    $(patsubst $(PRODUCT_MODULES_DIR)/%/lib,%,$(LIBRARY_MODULES))
+
+# Prefer sources over pre-built libraries for modules that provide both
+LIBRARY_MODULES := \
+    $(filter-out $(SOURCE_MODULES),$(LIBRARY_MODULES))
+
+# Select the library modules for the current firmware
+LIBRARY_MODULES := $(filter $(FIRMWARE_MODULES_LIST),$(LIBRARY_MODULES))
+
+# Divide libraries into two groups
+LIBRARY_MODULES_STANDARD := $(filter $(LIBRARY_MODULES),$(ALL_STANDARD_MODULES))
+LIBRARY_MODULES_PRODUCT := $(filter $(LIBRARY_MODULES),$(ALL_PRODUCT_MODULES))
+
 # Modules selected to be built into the firmware
 BUILD_STANDARD_MODULES := $(filter $(ALL_STANDARD_MODULES), \
-                                   $(FIRMWARE_MODULES_LIST))
+                                   $(SOURCE_MODULES))
 BUILD_PRODUCT_MODULES := $(filter $(ALL_PRODUCT_MODULES), \
-                                  $(FIRMWARE_MODULES_LIST))
+                                  $(SOURCE_MODULES))
 
 # Module selected to have their headers made available for inclusion by other
 # modules and their configuration files. These modules are not built into the
@@ -169,7 +204,6 @@ else
 endif
 export BUILD_HAS_NOTIFICATION
 
-
 # Add directories to the list of targets to build
 LIB_TARGETS_y += $(patsubst %,$(MODULES_DIR)/%/src, \
                             $(BUILD_STANDARD_MODULES))
@@ -181,11 +215,19 @@ MODULE_LIBS_y += $(patsubst %, \
     $(BUILD_FIRMWARE_DIR)/module/%$(BUILD_SUFFIX)/$(MODE)/lib/lib.a, \
     $(BUILD_STANDARD_MODULES) $(BUILD_PRODUCT_MODULES))
 
-# Create a list of include directories from the selected modules
+# Add path for libraries
+MODULE_LIBS_y += $(foreach module,$(LIBRARY_MODULES_STANDARD), \
+    $(MODULES_DIR)/$(module)/lib/mod_$(module).a)
+MODULE_LIBS_y += $(foreach module,$(LIBRARY_MODULES_PRODUCT), \
+    $(PRODUCT_MODULES_DIR)/$(module)/lib/mod_$(module).a)
+
+# Create a list of include directories from the selected modules and libraries
 MODULE_INCLUDES += $(patsubst %,$(MODULES_DIR)/%/include, \
-                              $(BUILD_STANDARD_MODULES))
+                              $(BUILD_STANDARD_MODULES) \
+                              $(LIBRARY_MODULES_STANDARD))
 MODULE_INCLUDES += $(patsubst %,$(PRODUCT_MODULES_DIR)/%/include, \
-                              $(BUILD_PRODUCT_MODULES))
+                              $(BUILD_PRODUCT_MODULES) \
+                              $(LIBRARY_MODULES_PRODUCT))
 MODULE_INCLUDES += $(patsubst %,$(MODULES_DIR)/%/include, \
                               $(HEADER_STANDARD_MODULES))
 MODULE_INCLUDES += $(patsubst %,$(PRODUCT_MODULES_DIR)/%/include, \
@@ -198,7 +240,7 @@ PRODUCT_INCLUDES += $(PRODUCT_DIR)/include
 # Add the firmware directory to the main INCLUDES list
 INCLUDES += $(FIRMWARE_DIR)
 
-# Add module and product includes to the main INCLUDES list
+# Add module, product and library includes to the main INCLUDES list
 export INCLUDES += $(MODULE_INCLUDES) $(PRODUCT_INCLUDES)
 
 #