powerpc: Introduce a new config symbol to control 16550 early debug code

The previous change by Kumar Gala in this area led to legacy_serial.c
and udbg_16550.c being built as modules when CONFIG_SERIAL_8250=m.
Fix this by introducing a new symbol, CONFIG_PPC_UDBG_16550, to
control whether these files get built, and arrange for it to be selected
for those platforms that need it.
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/Kconfig

@@ -275,6 +275,7 @@ config PPC_PSERIES
 	select PPC_I8259
 	select PPC_RTAS
 	select RTAS_ERROR_LOGGING
+	select PPC_UDBG_16550
 	default y
 
 config PPC_CHRP
@@ -284,6 +285,7 @@ config PPC_CHRP
 	select PPC_INDIRECT_PCI
 	select PPC_RTAS
 	select PPC_MPC106
+	select PPC_UDBG_16550
 	default y
 
 config PPC_PMAC
@@ -306,6 +308,7 @@ config PPC_PREP
 	depends on PPC_MULTIPLATFORM && PPC32 && BROKEN
 	select PPC_I8259
 	select PPC_INDIRECT_PCI
+	select PPC_UDBG_16550
 	default y
 
 config PPC_MAPLE
@@ -314,6 +317,7 @@ config PPC_MAPLE
 	select U3_DART
 	select MPIC_BROKEN_U3
 	select GENERIC_TBSYNC
+	select PPC_UDBG_16550
 	default n
 	help
           This option enables support for the Maple 970FX Evaluation Board.
@@ -324,6 +328,7 @@ config PPC_CELL
 	depends on PPC_MULTIPLATFORM && PPC64
 	select PPC_RTAS
 	select MMIO_NVRAM
+	select PPC_UDBG_16550
 
 config PPC_OF
 	def_bool y
@@ -370,6 +375,10 @@ config MPIC_BROKEN_U3
 	depends on PPC_MAPLE
 	default y
 
+config PPC_UDBG_16550
+	bool
+	default n
+
 config CELL_IIC
 	depends on PPC_CELL
 	bool

arch/powerpc/kernel/Makefile

@@ -55,7 +55,7 @@ obj-$(CONFIG_BOOTX_TEXT)	+= btext.o
 obj-$(CONFIG_6xx)		+= idle_6xx.o
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
-obj-$(CONFIG_SERIAL_8250)	+= legacy_serial.o udbg_16550.o
+obj-$(CONFIG_PPC_UDBG_16550)	+= legacy_serial.o udbg_16550.o
 module-$(CONFIG_PPC64)		+= module_64.o
 obj-$(CONFIG_MODULES)		+= $(module-y)
 

arch/powerpc/kernel/setup_32.c

@@ -299,9 +299,7 @@ void __init setup_arch(char **cmdline_p)
 	if (ppc_md.init_early)
 		ppc_md.init_early();
 
-#ifdef CONFIG_SERIAL_8250
 	find_legacy_serial_ports();
-#endif
 	finish_device_tree();
 
 	smp_setup_cpu_maps();

arch/powerpc/kernel/setup_64.c

@@ -472,9 +472,7 @@ void __init setup_system(void)
 	 * hash table management for us, thus ioremap works. We do that early
 	 * so that further code can be debugged
 	 */
-#ifdef CONFIG_SERIAL_8250
 	find_legacy_serial_ports();
-#endif
 
 	/*
 	 * "Finish" the device-tree, that is do the actual parsing of

arch/powerpc/platforms/maple/setup.c

@@ -71,9 +71,6 @@
 #define DBG(fmt...)
 #endif
 
-extern void generic_find_legacy_serial_ports(u64 *physport,
-		unsigned int *default_speed);
-
 static void maple_restart(char *cmd)
 {
 	unsigned int maple_nvram_base;

include/asm-powerpc/serial.h

@@ -15,6 +15,10 @@
 /* Default baud base if not found in device-tree */
 #define BASE_BAUD ( 1843200 / 16 )
 
+#ifdef CONFIG_PPC_UDBG_16550
 extern void find_legacy_serial_ports(void);
+#else
+#define find_legacy_serial_ports()	do { } while (0)
+#endif
 
 #endif /* _PPC64_SERIAL_H */