feat(st): add early console in BL2

Add an early UART console to ease debug before UART is fully configured.
This is done under flag STM32MP_EARLY_CONSOLE in the first STM32MP1
platform function called (bl2_el3_early_platform_setup()). It uses the
parameters defined for crash console: STM32MP_DEBUG_USART* macros.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Id6be62368723a0499e97bbf56fb52c166fcbdfad
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index a13e9e5..d8d1c13 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -62,6 +62,14 @@
 /* Setup the UART console */
 int stm32mp_uart_console_setup(void);
 
+#if STM32MP_EARLY_CONSOLE
+void stm32mp_setup_early_console(void);
+#else
+static inline void stm32mp_setup_early_console(void)
+{
+}
+#endif
+
 /*
  * Platform util functions for the GPIO driver
  * @bank: Target GPIO bank ID as per DT bindings
diff --git a/plat/st/common/stm32mp_common.c b/plat/st/common/stm32mp_common.c
index 2297cd6..f99cad5 100644
--- a/plat/st/common/stm32mp_common.c
+++ b/plat/st/common/stm32mp_common.c
@@ -205,10 +205,27 @@
 }
 #endif
 
+static void set_console(uintptr_t base, uint32_t clk_rate)
+{
+	unsigned int console_flags;
+
+	if (console_stm32_register(base, clk_rate,
+				   STM32MP_UART_BAUDRATE, &console) == 0) {
+		panic();
+	}
+
+	console_flags = CONSOLE_FLAG_BOOT | CONSOLE_FLAG_CRASH |
+			CONSOLE_FLAG_TRANSLATE_CRLF;
+#if !defined(IMAGE_BL2) && defined(DEBUG)
+	console_flags |= CONSOLE_FLAG_RUNTIME;
+#endif
+
+	console_set_scope(&console, console_flags);
+}
+
 int stm32mp_uart_console_setup(void)
 {
 	struct dt_node_info dt_uart_info;
-	unsigned int console_flags;
 	uint32_t clk_rate = 0U;
 	int result;
 	uint32_t boot_itf __unused;
@@ -249,21 +266,19 @@
 	clk_rate = clk_get_rate((unsigned long)dt_uart_info.clock);
 #endif
 
-	if (console_stm32_register(dt_uart_info.base, clk_rate,
-				   STM32MP_UART_BAUDRATE, &console) == 0) {
-		panic();
-	}
-
-	console_flags = CONSOLE_FLAG_BOOT | CONSOLE_FLAG_CRASH |
-			CONSOLE_FLAG_TRANSLATE_CRLF;
-#if !defined(IMAGE_BL2) && defined(DEBUG)
-	console_flags |= CONSOLE_FLAG_RUNTIME;
-#endif
-	console_set_scope(&console, console_flags);
+	set_console(dt_uart_info.base, clk_rate);
 
 	return 0;
 }
 
+#if STM32MP_EARLY_CONSOLE
+void stm32mp_setup_early_console(void)
+{
+	plat_crash_console_init();
+	set_console(STM32MP_DEBUG_USART_BASE, STM32MP_DEBUG_USART_CLK_FRQ);
+}
+#endif /* STM32MP_EARLY_CONSOLE */
+
 /*****************************************************************************
  * plat_is_smccc_feature_available() - This function checks whether SMCCC
  *                                     feature is availabile for platform.
diff --git a/plat/st/stm32mp1/bl2_plat_setup.c b/plat/st/stm32mp1/bl2_plat_setup.c
index 1504360..33ad56f 100644
--- a/plat/st/stm32mp1/bl2_plat_setup.c
+++ b/plat/st/stm32mp1/bl2_plat_setup.c
@@ -139,6 +139,8 @@
 				  u_register_t arg2 __unused,
 				  u_register_t arg3 __unused)
 {
+	stm32mp_setup_early_console();
+
 	stm32mp_save_boot_ctx_address(arg0);
 }
 
diff --git a/plat/st/stm32mp1/platform.mk b/plat/st/stm32mp1/platform.mk
index 65eaa74..8d4320a 100644
--- a/plat/st/stm32mp1/platform.mk
+++ b/plat/st/stm32mp1/platform.mk
@@ -9,6 +9,8 @@
 BL2_AT_EL3		:=	1
 USE_COHERENT_MEM	:=	0
 
+STM32MP_EARLY_CONSOLE	?=	0
+
 # Allow TF-A to concatenate BL2 & BL32 binaries in a single file,
 # share DTB file between BL2 and BL32
 # If it is set to 0, then FIP is used
@@ -157,6 +159,7 @@
 		PLAT_XLAT_TABLES_DYNAMIC \
 		STM32MP_DDR_32BIT_INTERFACE \
 		STM32MP_DDR_DUAL_AXI_PORT \
+		STM32MP_EARLY_CONSOLE \
 		STM32MP_EMMC \
 		STM32MP_EMMC_BOOT \
 		STM32MP_RAW_NAND \
@@ -183,6 +186,7 @@
 		STM32_TF_VERSION \
 		STM32MP_DDR_32BIT_INTERFACE \
 		STM32MP_DDR_DUAL_AXI_PORT \
+		STM32MP_EARLY_CONSOLE \
 		STM32MP_EMMC \
 		STM32MP_EMMC_BOOT \
 		STM32MP_RAW_NAND \