stm32mp1: Add DDR support and its security with TZC400

The DDR driver is under dual license, BSD and GPLv2.
The configuration parameters are taken from device tree.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
diff --git a/include/drivers/st/stm32mp1_ddr_helpers.h b/include/drivers/st/stm32mp1_ddr_helpers.h
new file mode 100644
index 0000000..298a080
--- /dev/null
+++ b/include/drivers/st/stm32mp1_ddr_helpers.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2017-2018, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __STM32MP1_DDR_HELPERS_H__
+#define __STM32MP1_DDR_HELPERS_H__
+
+void ddr_enable_clock(void);
+
+#endif /* __STM32MP1_DDR_HELPERS_H__ */