usb: omap1: Tahvo USB transceiver driver

Add Tahvo USB transceiver driver.

Based on old code from linux-omap tree. The original driver was written
by Juha Yrjölä, Tony Lindgren, and Timo Teräs.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Felipe Balbi <balbi@ti.com>

Documentation/ABI/testing/sysfs-platform-tahvo-usb

+What:		/sys/bus/platform/devices/tahvo-usb/otg_mode
+Date:		December 2013
+Contact:	Aaro Koskinen <aaro.koskinen@iki.fi>
+Description:
+		Set or read the current OTG mode. Valid values are "host" and
+		"peripheral".
+
+		Reading: returns the current mode.
+
+What:		/sys/bus/platform/devices/tahvo-usb/vbus
+Date:		December 2013
+Contact:	Aaro Koskinen <aaro.koskinen@iki.fi>
+Description:
+		Read the current VBUS state.
+
+		Reading: returns "on" or "off".

drivers/usb/phy/Kconfig

@@ -152,6 +152,21 @@ config OMAP_OTG
 	  This driver can also be built as a module. If so, the module
 	  will be called omap-otg.
 
+config TAHVO_USB
+	tristate "Tahvo USB transceiver driver"
+	depends on MFD_RETU && EXTCON
+	select USB_PHY
+	help
+	  Enable this to support USB transceiver on Tahvo. This is used
+	  at least on Nokia 770.
+
+config TAHVO_USB_HOST_BY_DEFAULT
+	depends on TAHVO_USB
+	boolean "Device in USB host mode by default"
+	help
+	  Say Y here, if you want the device to enter USB host mode
+	  by default on bootup.
+
 config USB_ISP1301
 	tristate "NXP ISP1301 USB transceiver support"
 	depends on USB || USB_GADGET

drivers/usb/phy/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_FSL_USB2_OTG)		+= phy-fsl-usb.o
 obj-$(CONFIG_ISP1301_OMAP)		+= phy-isp1301-omap.o
 obj-$(CONFIG_MV_U3D_PHY)		+= phy-mv-u3d-usb.o
 obj-$(CONFIG_NOP_USB_XCEIV)		+= phy-generic.o
+obj-$(CONFIG_TAHVO_USB)			+= phy-tahvo.o
 obj-$(CONFIG_OMAP_CONTROL_USB)		+= phy-omap-control.o
 obj-$(CONFIG_AM335X_CONTROL_USB)	+= phy-am335x-control.o
 obj-$(CONFIG_AM335X_PHY_USB)		+= phy-am335x.o