powerpc: Add a configuration option for early BootX/OpenFirmware debug

Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/Kconfig.debug

@@ -147,6 +147,13 @@ choice
 	  enable debugging for the wrong type of machine your kernel
 	  _will not boot_.
 
+config PPC_EARLY_DEBUG_BOOTX
+	bool "BootX or OpenFirmware"
+	depends on BOOTX_TEXT
+	help
+	  Select this to enable early debugging for a machine using BootX
+	  or OpenFirmware.
+
 config PPC_EARLY_DEBUG_LPAR
 	bool "LPAR HV Console"
 	depends on PPC_PSERIES

arch/powerpc/kernel/udbg.c

@@ -50,7 +50,7 @@ void __init udbg_early_init(void)
 	udbg_init_debug_beat();
 #elif defined(CONFIG_PPC_EARLY_DEBUG_PAS_REALMODE)
 	udbg_init_pas_realmode();
-#elif defined(CONFIG_BOOTX_TEXT)
+#elif defined(CONFIG_PPC_EARLY_DEBUG_BOOTX)
 	udbg_init_btext();
 #elif defined(CONFIG_PPC_EARLY_DEBUG_44x)
 	/* PPC44x debug */