mmc: Add new VUB300 USB-to-SD/SDIO/MMC driver

Add a driver for Elan Digital System's VUB300 chip which is a USB
connected SDIO/SDmem/MMC host controller.  A VUB300 chip enables a USB 2.0
or USB 1.1 connected host computer to use SDIO/SD/MMC cards without the
need for a directly connected, for example via PCI, SDIO host controller.

Signed-off-by: Anthony F Olech <tony.olech@elandigitalsystems.com>
[cjb: various punctuation and style fixes]
Tested-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

MAINTAINERS

@@ -6778,6 +6778,13 @@ L:	lm-sensors@lm-sensors.org
 S:	Maintained
 F:	drivers/hwmon/vt8231.c
 
+VUB300 USB to SDIO/SD/MMC bridge chip
+M:	Tony Olech <tony.olech@elandigitalsystems.com>
+L:	linux-mmc@vger.kernel.org
+L:	linux-usb@vger.kernel.org
+S:	Supported
+F:	drivers/mmc/host/vub300.c
+
 W1 DALLAS'S 1-WIRE BUS
 M:	Evgeniy Polyakov <johnpol@2ka.mipt.ru>
 S:	Maintained

drivers/mmc/host/Kconfig

@@ -535,6 +535,37 @@ config MMC_JZ4740
 	  If you have a board based on such a SoC and with a SD/MMC slot,
 	  say Y or M here.
 
+config MMC_VUB300
+	tristate "VUB300 USB to SDIO/SD/MMC Host Controller support"
+	depends on USB
+	help
+	  This selects support for Elan Digital Systems' VUB300 chip.
+
+	  The VUB300 is a USB-SDIO Host Controller Interface chip
+	  that enables the host computer to use SDIO/SD/MMC cards
+	  via a USB 2.0 or USB 1.1 host.
+
+	  The VUB300 chip will be found in both physically separate
+	  USB to SDIO/SD/MMC adapters and embedded on some motherboards.
+
+	  The VUB300 chip supports SD and MMC memory cards in addition
+	  to single and multifunction SDIO cards.
+
+	  Some SDIO cards will need a firmware file to be loaded and
+	  sent to VUB300 chip in order to achieve better data throughput.
+	  Download these "Offload Pseudocode" from Elan Digital Systems'
+	  web-site http://www.elandigitalsystems.com/support/downloads.php
+	  and put them in /lib/firmware. Note that without these additional
+	  firmware files the VUB300 chip will still function, but not at
+	  the best obtainable data rate.
+
+	  To compile this mmc host controller driver as a module,
+	  choose M here: the module will be called vub300.
+
+	  If you have a computer with an embedded VUB300 chip
+	  or if you intend connecting a USB adapter based on a
+	  VUB300 chip say Y or M here.
+
 config MMC_USHC
 	tristate "USB SD Host Controller (USHC) support"
 	depends on USB

drivers/mmc/host/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_SDH_BFIN)		+= bfin_sdh.o
 obj-$(CONFIG_MMC_DW)		+= dw_mmc.o
 obj-$(CONFIG_MMC_SH_MMCIF)	+= sh_mmcif.o
 obj-$(CONFIG_MMC_JZ4740)	+= jz4740_mmc.o
+obj-$(CONFIG_MMC_VUB300)	+= vub300.o
 obj-$(CONFIG_MMC_USHC)		+= ushc.o
 
 obj-$(CONFIG_MMC_SDHCI_PLTFM)			+= sdhci-platform.o