usb: Add support for indicating whether a port is removable

Userspace may want to make policy decisions based on whether or not a
given USB device is removable. Add a per-device member and support
for exposing it in sysfs. Information sources to populate it will be
added later.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index b4f5487..7c22a532 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -182,3 +182,14 @@
 		USB2 hardware LPM is enabled for the device. Developer can
 		write y/Y/1 or n/N/0 to the file to enable/disable the
 		feature.
+
+What:		/sys/bus/usb/devices/.../removable
+Date:		February 2012
+Contact:	Matthew Garrett <mjg@redhat.com>
+Description:
+		Some information about whether a given USB device is
+		physically fixed to the platform can be inferred from a
+		combination of hub decriptor bits and platform-specific data
+		such as ACPI. This file will read either "removable" or
+		"fixed" if the information is available, and "unknown"
+		otherwise.
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