nxp: added csu driver

NXP Central Security Unit(CSU) for NXP SoC.
CSU is used for:
- Access permissions for peripheral that donot have their own
  access control.
- Locking of individual CSU settings until the next POR
- General purpose security related control bits

Refer NXP SoC manuals fro more details.

Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Change-Id: I07a4729c79c5e2597f8b2a782e87e09f7f30c2ca
diff --git a/drivers/nxp/csu/csu.mk b/drivers/nxp/csu/csu.mk
new file mode 100644
index 0000000..ebdf674
--- /dev/null
+++ b/drivers/nxp/csu/csu.mk
@@ -0,0 +1,28 @@
+#
+# Copyright 2020 NXP
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+#-----------------------------------------------------------------------------
+ifeq (${CSU_ADDED},)
+
+CSU_ADDED		:= 1
+
+CSU_DRIVERS_PATH	:=  ${PLAT_DRIVERS_PATH}/csu
+
+PLAT_INCLUDES		+= -I$(CSU_DRIVERS_PATH)
+
+CSU_SOURCES		+= $(CSU_DRIVERS_PATH)/csu.c
+
+ifeq (${BL_COMM_CSU_NEEDED},yes)
+BL_COMMON_SOURCES	+= ${CSU_SOURCES}
+else
+ifeq (${BL2_CSU_NEEDED},yes)
+BL2_SOURCES		+= ${CSU_SOURCES}
+endif
+ifeq (${BL31_CSU_NEEDED},yes)
+BL31_SOURCES		+= ${CSU_SOURCES}
+endif
+endif
+
+endif