refactor(plat/st): avoid fixed DT address

Device Tree address is now a parameter for dt_open_and_check() function.
This will allow better flexibility when introducing PIE and FIP.
The fdt pointer is now only assigned if the given address holds
a valid device tree file. This allows removing the fdt_checked variable,
as we now check fdt is not null.

Change-Id: I04cbb2fc05c9c711ae1c77d56368dbeb6dd4b01a
Signed-off-by: Yann Gautier <yann.gautier@st.com>

plat/st/common/include/stm32mp_dt.h

 /*
- * Copyright (c) 2020, STMicroelectronics - All Rights Reserved
- * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020-2021, STMicroelectronics - All Rights Reserved
+ * Copyright (c) 2017-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,6 +9,7 @@
 #define STM32MP_DT_H
 
 #include <stdbool.h>
+#include <stdint.h>
 
 #define DT_DISABLED		U(0)
 #define DT_NON_SECURE		U(1)
@@ -25,7 +26,7 @@ struct dt_node_info {
 /*******************************************************************************
  * Function and variable prototypes
  ******************************************************************************/
-int dt_open_and_check(void);
+int dt_open_and_check(uintptr_t dt_addr);
 int fdt_get_address(void **fdt_addr);
 bool fdt_check_node(int node);
 uint8_t fdt_get_status(int node);

plat/st/common/stm32mp_dt.c

@@ -19,20 +19,19 @@
 
 #include <stm32mp_dt.h>
 
-static int fdt_checked;
-
-static void *fdt = (void *)(uintptr_t)STM32MP_DTB_BASE;
+static void *fdt;
 
 /*******************************************************************************
  * This function checks device tree file with its header.
  * Returns 0 on success and a negative FDT error code on failure.
  ******************************************************************************/
-int dt_open_and_check(void)
+int dt_open_and_check(uintptr_t dt_addr)
 {
-	int ret = fdt_check_header(fdt);
+	int ret;
 
+	ret = fdt_check_header((void *)dt_addr);
 	if (ret == 0) {
-		fdt_checked = 1;
+		fdt = (void *)dt_addr;
 	}
 
 	return ret;
@@ -45,11 +44,13 @@ int dt_open_and_check(void)
  ******************************************************************************/
 int fdt_get_address(void **fdt_addr)
 {
-	if (fdt_checked == 1) {
-		*fdt_addr = fdt;
+	if (fdt == NULL) {
+		return 0;
 	}
 
-	return fdt_checked;
+	*fdt_addr = fdt;
+
+	return 1;
 }
 
 /*******************************************************************************

plat/st/stm32mp1/bl2_plat_setup.c

@@ -196,7 +196,7 @@ void bl2_el3_plat_arch_setup(void)
 
 	configure_mmu();
 
-	if (dt_open_and_check() < 0) {
+	if (dt_open_and_check(STM32MP_DTB_BASE) < 0) {
 		panic();
 	}
 

plat/st/stm32mp1/sp_min/sp_min_setup.c

@@ -146,7 +146,7 @@ void sp_min_early_platform_setup2(u_register_t arg0, u_register_t arg1,
 		bl_params = bl_params->next_params_info;
 	}
 
-	if (dt_open_and_check() < 0) {
+	if (dt_open_and_check(STM32MP_DTB_BASE) < 0) {
 		panic();
 	}