usb: gadget: f_subset: add configfs support

f_subset learns about configfs so we can, eventually,
remove in-kernel gadget drivers.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/Documentation/ABI/testing/configfs-usb-gadget-subset b/Documentation/ABI/testing/configfs-usb-gadget-subset
new file mode 100644
index 0000000..f47170a
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-subset
@@ -0,0 +1,14 @@
+What:		/config/usb-gadget/gadget/functions/geth.name
+Date:		May 2013
+KenelVersion:	3.11
+Description:
+		The attributes:
+
+		ifname		- network device interface name associated with
+				this function instance
+		qmult		- queue length multiplier for high and
+				super speed
+		host_addr	- MAC address of host's end of this
+				Ethernet over USB link
+		dev_addr	- MAC address of device's end of this
+				Ethernet over USB link