stm32mp1: add a function to get non-secure DDR size

This function gets the DDR size from DT, and withdraws (if defined) the
sizes of secure DDR and shared memory areas.
This function also checks DT values fits the default DDR range.
This non-secure memory is available for BL33 and non-secure OS.

Change-Id: I162ae5e990a0f9b6b7d07e539de029f1d61a391b
Signed-off-by: Yann Gautier <yann.gautier@st.com>

plat/st/stm32mp1/include/stm32mp1_private.h

 /*
- * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -21,4 +21,5 @@ void stm32mp1_syscfg_init(void);
 void stm32mp1_syscfg_enable_io_compensation(void);
 void stm32mp1_syscfg_disable_io_compensation(void);
 
+uint32_t stm32mp_get_ddr_ns_size(void);
 #endif /* STM32MP1_PRIVATE_H */

plat/st/stm32mp1/stm32mp1_def.h

 /*
- * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -62,6 +62,9 @@
 #ifdef AARCH32_SP_OPTEE
 #define STM32MP_DDR_S_SIZE		U(0x01E00000)	/* 30 MB */
 #define STM32MP_DDR_SHMEM_SIZE		U(0x00200000)	/* 2 MB */
+#else
+#define STM32MP_DDR_S_SIZE		U(0)
+#define STM32MP_DDR_SHMEM_SIZE		U(0)
 #endif
 
 /* DDR power initializations */

plat/st/stm32mp1/stm32mp1_private.c

 /*
- * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -365,3 +365,24 @@ uint32_t stm32_iwdg_shadow_update(uint32_t iwdg_inst, uint32_t flags)
 	return BSEC_OK;
 }
 #endif
+
+/* Get the non-secure DDR size */
+uint32_t stm32mp_get_ddr_ns_size(void)
+{
+	static uint32_t ddr_ns_size;
+	uint32_t ddr_size;
+
+	if (ddr_ns_size != 0U) {
+		return ddr_ns_size;
+	}
+
+	ddr_size = dt_get_ddr_size();
+	if ((ddr_size <= (STM32MP_DDR_S_SIZE + STM32MP_DDR_SHMEM_SIZE)) ||
+	    (ddr_size > STM32MP_DDR_MAX_SIZE)) {
+		panic();
+	}
+
+	ddr_ns_size = ddr_size - (STM32MP_DDR_S_SIZE + STM32MP_DDR_SHMEM_SIZE);
+
+	return ddr_ns_size;
+}