stm32mp1: Allow to activate CONFIG_DEBUG_UART

Add the needed information to enable the debug uart
to have printf before the serial driver probe
(so before probe for clock, pincontrol and reset drivers)

To enable the debug on uart 4 (default console):
+ CONFIG_DEBUG_UART=y
+ CONFIG_DEBUG_UART_STM32=y

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

arch/arm/mach-stm32mp/Kconfig

@@ -54,4 +54,19 @@ config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION_MMC2
 
 source "board/st/stm32mp1/Kconfig"
 
+# currently activated for debug / should be deactivated for real product
+if DEBUG_UART
+
+config DEBUG_UART_BOARD_INIT
+	default y
+
+# debug on UART4 by default
+config DEBUG_UART_BASE
+	default 0x40010000
+
+# clock source is HSI on reset
+config DEBUG_UART_CLOCK
+	default 64000000
+endif
+
 endif

arch/arm/mach-stm32mp/cpu.c

@@ -4,6 +4,7 @@
  */
 #include <common.h>
 #include <clk.h>
+#include <debug_uart.h>
 #include <asm/io.h>
 #include <asm/arch/stm32.h>
 #include <asm/arch/sys_proto.h>
@@ -152,6 +153,8 @@ static u32 get_bootmode(void)
  */
 int arch_cpu_init(void)
 {
+	u32 boot_mode;
+
 	/* early armv7 timer init: needed for polling */
 	timer_init();
 
@@ -160,8 +163,17 @@ int arch_cpu_init(void)
 
 	security_init();
 #endif
+
 	/* get bootmode from BootRom context: saved in TAMP register */
-	get_bootmode();
+	boot_mode = get_bootmode();
+
+	if ((boot_mode & TAMP_BOOT_DEVICE_MASK) == BOOT_SERIAL_UART)
+		gd->flags |= GD_FLG_SILENT | GD_FLG_DISABLE_CONSOLE;
+#if defined(CONFIG_DEBUG_UART) && \
+	(!defined(CONFIG_SPL) || defined(CONFIG_SPL_BUILD))
+	else
+		debug_uart_init();
+#endif
 
 	return 0;
 }

arch/arm/mach-stm32mp/include/mach/stm32.h

@@ -17,6 +17,18 @@
 #define STM32_ETZPC_BASE		0x5C007000
 #define STM32_TAMP_BASE			0x5C00A000
 
+#ifdef CONFIG_DEBUG_UART_BASE
+/* hardcoded value can be only used for DEBUG UART */
+#define STM32_USART1_BASE		0x5C000000
+#define STM32_USART2_BASE		0x4000E000
+#define STM32_USART3_BASE		0x4000F000
+#define STM32_UART4_BASE		0x40010000
+#define STM32_UART5_BASE		0x40011000
+#define STM32_USART6_BASE		0x44003000
+#define STM32_UART7_BASE		0x40018000
+#define STM32_UART8_BASE		0x40019000
+#endif
+
 #define STM32_SYSRAM_BASE		0x2FFC0000
 #define STM32_SYSRAM_SIZE		SZ_256K
 

board/st/stm32mp1/board.c

@@ -10,6 +10,33 @@
 #include <power/pmic.h>
 #include <power/stpmu1.h>
 
+#ifdef CONFIG_DEBUG_UART_BOARD_INIT
+void board_debug_uart_init(void)
+{
+#if (CONFIG_DEBUG_UART_BASE == STM32_UART4_BASE)
+
+#define RCC_MP_APB1ENSETR (STM32_RCC_BASE + 0x0A00)
+#define RCC_MP_AHB4ENSETR (STM32_RCC_BASE + 0x0A28)
+
+	/* UART4 clock enable */
+	setbits_le32(RCC_MP_APB1ENSETR, BIT(16));
+
+#define GPIOG_BASE 0x50008000
+	/* GPIOG clock enable */
+	writel(BIT(6), RCC_MP_AHB4ENSETR);
+	/* GPIO configuration for EVAL board
+	 * => Uart4 TX = G11
+	 */
+	writel(0xffbfffff, GPIOG_BASE + 0x00);
+	writel(0x00006000, GPIOG_BASE + 0x24);
+#else
+
+#error("CONFIG_DEBUG_UART_BASE: not supported value")
+
+#endif
+}
+#endif
+
 #ifdef CONFIG_PMIC_STPMU1
 int board_ddr_power_init(void)
 {