Invalidate dcache build option for bl2 entry at EL3

Some of the platform (ie. Agilex) make use of CCU IPs which will only be
initialized during bl2_el3_early_platform_setup. Any operation to the
cache beforehand will crash the platform. Hence, this will provide an
option to skip the data cache invalidation upon bl2 entry at EL3

Signed-off-by: Hadi Asyrafi <muhammad.hadi.asyrafi.abdul.halim@intel.com>
Change-Id: I2c924ed0589a72d0034714c31be8fe57237d1f06

Makefile

@@ -689,6 +689,7 @@ $(eval $(call assert_boolean,USE_TBBR_DEFS))
 $(eval $(call assert_boolean,WARMBOOT_ENABLE_DCACHE_EARLY))
 $(eval $(call assert_boolean,BL2_AT_EL3))
 $(eval $(call assert_boolean,BL2_IN_XIP_MEM))
+$(eval $(call assert_boolean,BL2_INV_DCACHE))
 
 $(eval $(call assert_numeric,ARM_ARCH_MAJOR))
 $(eval $(call assert_numeric,ARM_ARCH_MINOR))
@@ -749,6 +750,7 @@ $(eval $(call add_define,USE_TBBR_DEFS))
 $(eval $(call add_define,WARMBOOT_ENABLE_DCACHE_EARLY))
 $(eval $(call add_define,BL2_AT_EL3))
 $(eval $(call add_define,BL2_IN_XIP_MEM))
+$(eval $(call add_define,BL2_INV_DCACHE))
 
 ifeq (${SANITIZE_UB},trap)
         $(eval $(call add_define,MONITOR_TRAPS))

docs/getting_started/user-guide.rst

@@ -287,6 +287,12 @@ Common build options
    enable this use-case. For now, this option is only supported when BL2_AT_EL3
    is set to '1'.
 
+-  ``BL2_INV_DCACHE``: This is an optional build option which control dcache
+   invalidation upon BL2 entry. Some platform cannot handle cache operations
+   during entry as the coherency unit is not yet initialized. This may cause
+   crashing. Leaving this option to '1' (default) will allow the operation.
+   This option is only relevant when BL2_AT_EL3 is set to '1'.
+
 -  ``BL31``: This is an optional build option which specifies the path to
    BL31 image for the ``fip`` target. In this case, the BL31 in TF-A will not
    be built.

include/arch/aarch64/el3_common_macros.S

@@ -333,7 +333,7 @@
 	 * ---------------------------------------------------------------------
 	 */
 	.if \_init_c_runtime
-#if defined(IMAGE_BL31) || (defined(IMAGE_BL2) && BL2_AT_EL3)
+#if defined(IMAGE_BL31) || (defined(IMAGE_BL2) && BL2_AT_EL3 && BL2_INV_DCACHE)
 		/* -------------------------------------------------------------
 		 * Invalidate the RW memory used by the BL31 image. This
 		 * includes the data and NOBITS sections. This is done to

make_helpers/defaults.mk

@@ -33,6 +33,9 @@ BL2_AT_EL3			:= 0
 # when BL2_AT_EL3 is 1.
 BL2_IN_XIP_MEM			:= 0
 
+# Do dcache invalidate upon BL2 entry at EL3
+BL2_INV_DCACHE			:= 1
+
 # Select the branch protection features to use.
 BRANCH_PROTECTION		:= 0
 

plat/intel/soc/agilex/platform.mk

@@ -70,5 +70,6 @@ BL31_SOURCES	+=	\
 
 PROGRAMMABLE_RESET_ADDRESS	:= 0
 BL2_AT_EL3			:= 1
+BL2_INV_DCACHE			:= 0
 MULTI_CONSOLE_API		:= 1
 USE_COHERENT_MEM		:= 1