USB: g_ffs: the FunctionFS gadget driver

The Function Filesystem (FunctioFS) lets one create USB
composite functions in user space in the same way as GadgetFS
lets one create USB gadgets in user space.  This allows
creation of composite gadgets such that some of the functions
are implemented in kernel space (for instance Ethernet, serial
or mass storage) and other are implemented in user space.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -710,6 +710,43 @@ config USB_GADGETFS
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "gadgetfs".
 
+config USB_FUNCTIONFS
+	tristate "Function Filesystem (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  The Function Filesystem (FunctioFS) lets one create USB
+	  composite functions in user space in the same way as GadgetFS
+	  lets one create USB gadgets in user space.  This allows creation
+	  of composite gadgets such that some of the functions are
+	  implemented in kernel space (for instance Ethernet, serial or
+	  mass storage) and other are implemented in user space.
+
+	  Say "y" to link the driver statically, or "m" to build
+	  a dynamically linked module called "g_ffs".
+
+config USB_FUNCTIONFS_ETH
+	bool "Include CDC ECM (Ethernet) function"
+	depends on USB_FUNCTIONFS
+	help
+	  Include an CDC ECM (Ethernet) funcion in the CDC ECM (Funcion)
+	  Filesystem.  If you also say "y" to the RNDIS query below the
+	  gadget will have two configurations.
+
+config USB_FUNCTIONFS_RNDIS
+	bool "Include RNDIS (Ethernet) function"
+	depends on USB_FUNCTIONFS
+	help
+	  Include an RNDIS (Ethernet) funcion in the Funcion Filesystem.
+	  If you also say "y" to the CDC ECM query above the gadget will
+	  have two configurations.
+
+config USB_FUNCTIONFS_GENERIC
+	bool "Include 'pure' configuration"
+	depends on USB_FUNCTIONFS && (USB_FUNCTIONFS_ETH || USB_FUNCTIONFS_RNDIS)
+	help
+	  Include a configuration with FunctionFS and no Ethernet
+	  configuration.
+
 config USB_FILE_STORAGE
 	tristate "File-backed Storage Gadget"
 	depends on BLOCK

drivers/usb/gadget/Makefile

@@ -51,6 +51,8 @@ obj-$(CONFIG_USB_ZERO)		+= g_zero.o
 obj-$(CONFIG_USB_AUDIO)		+= g_audio.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
+obj-$(CONFIG_USB_FUNCTIONFS)	+= g_ffs.o
+obj-$(CONFIG_USB_ETH_FUNCTIONFS)	+= g_eth_ffs.o
 obj-$(CONFIG_USB_FILE_STORAGE)	+= g_file_storage.o
 obj-$(CONFIG_USB_MASS_STORAGE)	+= g_mass_storage.o
 obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o