Replace build macro WARN_DEPRECATED with ERROR_DEPRECATED

This patch changes the build time behaviour when using deprecated API within
Trusted Firmware. Previously the use of deprecated APIs would only trigger a
build warning (which was always treated as a build error), when
WARN_DEPRECATED = 1. Now, the use of deprecated C declarations will always
trigger a build time warning. Whether this warning is treated as error or not
is determined by the build flag ERROR_DEPRECATED which is disabled by default.
When the build flag ERROR_DEPRECATED=1, the invocation of deprecated API or
inclusion of deprecated headers will result in a build error.

Also the deprecated context management helpers in context_mgmt.c are now
conditionally compiled depending on the value of ERROR_DEPRECATED flag
so that the APIs themselves do not result in a build error when the
ERROR_DEPRECATED flag is set.

NOTE: Build systems that use the macro WARN_DEPRECATED must migrate to
using ERROR_DEPRECATED, otherwise deprecated API usage will no longer
trigger a build error.

Change-Id: I843bceef6bde979af7e9b51dddf861035ec7965a

Makefile

@@ -87,8 +87,8 @@ TRUSTED_BOARD_BOOT		:= 0
 # By default, consider that the platform's reset address is not programmable.
 # The platform Makefile is free to override this value.
 PROGRAMMABLE_RESET_ADDRESS	:= 0
-# Build flag to warn about usage of deprecated platform and framework APIs
+# Build flag to treat usage of deprecated platform and framework APIs as error.
-WARN_DEPRECATED			:= 0
+ERROR_DEPRECATED		:= 0
 
 
 ################################################################################
@@ -346,7 +346,7 @@ $(eval $(call assert_boolean,SAVE_KEYS))
 $(eval $(call assert_boolean,TRUSTED_BOARD_BOOT))
 $(eval $(call assert_boolean,PROGRAMMABLE_RESET_ADDRESS))
 $(eval $(call assert_boolean,PSCI_EXTENDED_STATE_ID))
-$(eval $(call assert_boolean,WARN_DEPRECATED))
+$(eval $(call assert_boolean,ERROR_DEPRECATED))
 $(eval $(call assert_boolean,ENABLE_PLAT_COMPAT))
 
 
@@ -368,7 +368,7 @@ $(eval $(call add_define,USE_COHERENT_MEM))
 $(eval $(call add_define,TRUSTED_BOARD_BOOT))
 $(eval $(call add_define,PROGRAMMABLE_RESET_ADDRESS))
 $(eval $(call add_define,PSCI_EXTENDED_STATE_ID))
-$(eval $(call add_define,WARN_DEPRECATED))
+$(eval $(call add_define,ERROR_DEPRECATED))
 $(eval $(call add_define,ENABLE_PLAT_COMPAT))
 
 
@@ -404,6 +404,11 @@ all: msg_start
 msg_start:
 	@echo "Building ${PLAT}"
 
+# Check if deprecated declarations should be treated as error or not.
+ifeq (${ERROR_DEPRECATED},0)
+    CFLAGS		+= 	-Wno-error=deprecated-declarations
+endif
+
 # Expand build macros for the different images
 ifeq (${NEED_BL1},yes)
 $(eval $(call MAKE_BL,1))

bl31/context_mgmt.c

@@ -90,6 +90,14 @@ void cm_set_context_by_index(unsigned int cpu_idx, void *context,
 	set_cpu_data_by_index(cpu_idx, cpu_context[security_state], context);
 }
 
+#if !ERROR_DEPRECATED
+/*
+ * These context management helpers are deprecated but are maintained for use
+ * by SPDs which have not migrated to the new API. If ERROR_DEPRECATED
+ * is enabled, these are excluded from the build so as to force users to
+ * migrate to the new API.
+ */
+
 /*******************************************************************************
  * This function returns a pointer to the most recent 'cpu_context' structure
  * for the CPU identified by MPIDR that was set as the context for the specified
@@ -114,6 +122,21 @@ void cm_set_context_by_mpidr(uint64_t mpidr, void *context, uint32_t security_st
 						 context, security_state);
 }
 
+/*******************************************************************************
+ * The following function provides a compatibility function for SPDs using the
+ * existing cm library routines. This function is expected to be invoked for
+ * initializing the cpu_context for the CPU specified by MPIDR for first use.
+ ******************************************************************************/
+void cm_init_context(unsigned long mpidr, const entry_point_info_t *ep)
+{
+	if ((mpidr & MPIDR_AFFINITY_MASK) ==
+			(read_mpidr_el1() & MPIDR_AFFINITY_MASK))
+		cm_init_my_context(ep);
+	else
+		cm_init_context_by_index(platform_get_core_pos(mpidr), ep);
+}
+#endif
+
 /*******************************************************************************
  * This function is used to program the context that's used for exception
  * return. This initializes the SP_EL3 to a pointer to a 'cpu_context' set for
@@ -260,20 +283,6 @@ void cm_init_my_context(const entry_point_info_t *ep)
 	cm_init_context_common(ctx, ep);
 }
 
-/*******************************************************************************
- * The following function provides a compatibility function for SPDs using the
- * existing cm library routines. This function is expected to be invoked for
- * initializing the cpu_context for the CPU specified by MPIDR for first use.
- ******************************************************************************/
-void cm_init_context(unsigned long mpidr, const entry_point_info_t *ep)
-{
-	if ((mpidr & MPIDR_AFFINITY_MASK) ==
-			(read_mpidr_el1() & MPIDR_AFFINITY_MASK))
-		cm_init_my_context(ep);
-	else
-		cm_init_context_by_index(platform_get_core_pos(mpidr), ep);
-}
-
 /*******************************************************************************
  * Prepare the CPU system registers for first entry into secure or normal world
  *

docs/user-guide.md

@@ -367,10 +367,10 @@ performed.
     and it governs the return value of PSCI_FEATURES API for CPU_SUSPEND
     smc function id.
 
-*   `WARN_DEPRECATED`: This option decides whether to warn the usage of
+*   `ERROR_DEPRECATED`: This option decides whether to treat the usage of
-    deprecated platform APIs and context management helpers within Trusted
+    deprecated platform APIs, helper functions or drivers within Trusted
-    Firmware. It can take the value 1 (warn the use of deprecated APIs) or
+    Firmware as error. It can take the value 1 (flag the use of deprecated
-    0. The default is 0.
+    APIs as error) or 0. The default is 0.
 
 #### ARM development platform specific build options
 

include/common/asm_macros.S

@@ -101,10 +101,10 @@
 
 	/*
 	 * Theses macros are used to create function labels for deprecated
-	 * APIs. If WARN_DEPRECATED is non zero, the callers of these APIs
+	 * APIs. If ERROR_DEPRECATED is non zero, the callers of these APIs
 	 * will fail to link and cause build failure.
 	 */
-#if WARN_DEPRECATED
+#if ERROR_DEPRECATED
 	.macro func_deprecated _name
 	func deprecated\_name
 	.endm

include/plat/common/common_def.h

@@ -69,15 +69,10 @@
 
 /*
  * Macros to wrap declarations of deprecated APIs within Trusted Firmware.
- * The callers of these APIs will continue to compile as long as the build
+ * The callers of these APIs will continue to compile with a warning as long
- * flag WARN_DEPRECATED is zero. Else the compiler will emit a warning
+ * as the build flag ERROR_DEPRECATED is zero.
- * when the callers of these APIs are compiled.
  */
-#if WARN_DEPRECATED
 #define __warn_deprecated	__attribute__ ((deprecated))
-#else
-#define __warn_deprecated
-#endif
 
 #endif /* __COMMON_DEF_H__ */