cdrom: Add support for Sega Dreamcast GD-ROM.

This patch adds support for the GD-Rom drive, SEGA's proprietary
implementation of an IDE CD Rom for the SEGA Dreamcast. This driver
implements Sega's Packet Interface (SPI) - at least partially. It will
also read disks in SEGA's propreitary GD format.

Unlike previous drivers (which were never in mainline) this uses DMA and
not PIO to read disks. It is a new driver, not a refactoring of old
drivers.

Signed-off by: Adrian McMenamin <adrian@mcmen.demon.co.uk>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/block/Kconfig

@@ -105,6 +105,17 @@ config PARIDE
 	  "MicroSolutions backpack protocol", "DataStor Commuter protocol"
 	  etc.).
 
+config GDROM
+	tristate "SEGA Dreamcast GD-ROM drive"
+	depends on SH_DREAMCAST
+	help
+	  A standard SEGA Dreamcast comes with a modified CD ROM drive called a
+	  "GD-ROM" by SEGA to signify it is capable of reading special disks
+	  with up to 1 GB of data. This drive will also read standard CD ROM
+	  disks. Select this option to access any disks in your GD ROM drive.
+	  Most users will want to say "Y" here.
+	  You can also build this as a module which will be called gdrom.ko
+
 source "drivers/block/paride/Kconfig"
 
 config BLK_CPQ_DA

drivers/cdrom/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_PARIDE_PCD)	+=		cdrom.o
 obj-$(CONFIG_CDROM_PKTCDVD)	+=		cdrom.o
 
 obj-$(CONFIG_VIOCD)		+= viocd.o      cdrom.o
+obj-$(CONFIG_GDROM)		+= gdrom.o      cdrom.o