console: Add Kconfig debug option DEBUG_CONSOLE_INIT

Under normal circumstances no printk() goes through until
console_hw_init() has completed. This is wanted behaviour,
except when you need to debug the setup of one of consoles.

Change-Id: Ifc2bb22bf930009ee229d4461f512ada3018307b
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/30558
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/Kconfig

@@ -782,6 +782,18 @@ config DEBUG_ACPI
 
 	  If unsure, say N.
 
+config DEBUG_CONSOLE_INIT
+	bool "Debug console initialisation code"
+	default n
+	help
+	  With this option printk()'s are attempted before console hardware
+	  initialisation has been completed. Your mileage may vary.
+
+	  Typically you will need to modify source in console_hw_init() such
+	  that a working console appears before the one you want to debug.
+
+	  If unsure, say N.
+
 # Only visible if debug level is DEBUG (7) or SPEW (8) as it does additional
 # printk(BIOS_DEBUG, ...) calls.
 config REALMODE_DEBUG

src/console/init.c

@@ -72,6 +72,9 @@ asmlinkage void console_init(void)
 {
 	init_log_level();
 
+	if (IS_ENABLED(CONFIG_DEBUG_CONSOLE_INIT))
+		car_set_var(console_inited, 1);
+
 #if IS_ENABLED(CONFIG_EARLY_PCI_BRIDGE)
 	if (!ENV_SMM && !ENV_RAMSTAGE)
 		pci_early_bridge_init();