sh: Add maple bus support for the SEGA Dreamcast.

The Maple bus is SEGA's proprietary serial bus for peripherals
(keyboard, mouse, controller etc). The bus is capable of some
(limited) hotplugging and operates at up to 2 M/bits.

Drivers of one sort or another existed/exist for 2.4 and a rudimentary
port, which didn't support the 2.6 device driver model was also in
existence.

This driver - for the bus logic itself and for the keyboard (other
drivers will follow) are based on the code and concepts of those old
drivers but have lots of completely rewritten parts.

I have the maple bus code as a built in now as that seems the sane and
rational way to handle something like that - you either want the bus
or you don't.

Signed-off-by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -666,6 +666,17 @@ config SUPERHYWAY
 	tristate "SuperHyway Bus support"
 	depends on CPU_SUBTYPE_SH4_202
 
+config MAPLE
+       bool "Maple Bus support"
+       depends on SH_DREAMCAST
+       help
+         The Maple Bus is SEGA's serial communication bus for peripherals
+         on the Dreamcast. Without this bus support you won't be able to
+         get your Dreamcast keyboard etc to work, so most users
+         probably want to say 'Y' here, unless you are only using the
+         Dreamcast with a serial line terminal or a remote network
+         connection.
+
 config CF_ENABLER
 	bool "Compact Flash Enabler support"
 	depends on SOLUTION_ENGINE || SH_SH03

drivers/sh/Makefile

@@ -2,5 +2,5 @@
 # Makefile for the SuperH specific drivers.
 #
 
-obj-$(CONFIG_SUPERHYWAY) += superhyway/
-
+obj-$(CONFIG_SUPERHYWAY)	+= superhyway/
+obj-$(CONFIG_MAPLE)		+= maple/

drivers/sh/maple/Makefile

@@ -0,0 +1,3 @@
+# Makefile for Maple Bus
+
+obj-$(CONFIG_MAPLE) := maple.o