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.h b/drivers/nxp/csu/csu.h
new file mode 100644
index 0000000..9f82feb
--- /dev/null
+++ b/drivers/nxp/csu/csu.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2020 NXP
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef CSU_H
+#define CSU_H
+
+#define CSU_SEC_ACCESS_REG_OFFSET	(0x0021CU)
+
+/* Macros defining access permissions to configure
+ * the regions controlled by Central Security Unit.
+ */
+enum csu_cslx_access {
+	CSU_NS_SUP_R = (0x8U),
+	CSU_NS_SUP_W = (0x80U),
+	CSU_NS_SUP_RW = (0x88U),
+	CSU_NS_USER_R = (0x4U),
+	CSU_NS_USER_W = (0x40U),
+	CSU_NS_USER_RW = (0x44U),
+	CSU_S_SUP_R = (0x2U),
+	CSU_S_SUP_W = (0x20U),
+	CSU_S_SUP_RW = (0x22U),
+	CSU_S_USER_R = (0x1U),
+	CSU_S_USER_W = (0x10U),
+	CSU_S_USER_RW = (0x11U),
+	CSU_ALL_RW = (0xffU),
+};
+
+struct csu_ns_dev_st {
+	uintptr_t ind;
+	uint32_t val;
+};
+
+void enable_layerscape_ns_access(struct csu_ns_dev_st *csu_ns_dev,
+				 uint32_t num, uintptr_t nxp_csu_addr);
+
+#endif