+/**
+ * struct usb_interface_cache - long-term representation of a device interface
+ * @num_altsetting: number of altsettings defined.
+ * @ref: reference counter.
+ * @altsetting: variable-length array of interface structures, one for
+ * each alternate setting that may be selected. Each one includes a
+ * set of endpoint configurations. They will be in no particular order.
+ *
+ * These structures persist for the lifetime of a usb_device, unlike
+ * struct usb_interface (which persists only as long as its configuration
+ * is installed). The altsetting arrays can be accessed through these
+ * structures at any time, permitting comparison of configurations and
+ * providing support for the /proc/bus/usb/devices pseudo-file.
+ */
+struct usb_interface_cache {
+ unsigned num_altsetting; /* number of alternate settings */
+ struct kref ref; /* reference counter */
+
+ /* variable-length array of alternate settings for this interface,
+ * stored in no particular order */
+ struct usb_host_interface altsetting[0];
+};
+#define ref_to_usb_interface_cache(r) \
+ container_of(r, struct usb_interface_cache, ref)
+#define altsetting_to_usb_interface_cache(a) \
+ container_of(a, struct usb_interface_cache, altsetting[0])
+