static inline int hub_is_superspeed(struct usb_device *hdev)
{
        return (hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS);
}

ch11.h:

/*
 * Hub Device descriptor
 * USB Hub class device protocols
 */

#define USB_HUB_PR_FS           0 /* Full speed hub */
#define USB_HUB_PR_HS_NO_TT     0 /* Hi-speed hub without TT */
#define USB_HUB_PR_HS_SINGLE_TT 1 /* Hi-speed hub with single TT */
#define USB_HUB_PR_HS_MULTI_TT  2 /* Hi-speed hub with multiple TT */
#define USB_HUB_PR_SS           3 /* Super speed hub */

ch9.h:
hubdev->state

enum usb_device_state {
        /* NOTATTACHED isn't in the USB spec, and this state acts
         * the same as ATTACHED ... but it's clearer this way.
         */
        USB_STATE_NOTATTACHED = 0,

        /* chapter 9 and authentication (wireless) device states */
        USB_STATE_ATTACHED,
        USB_STATE_POWERED,                      /* wired */
        USB_STATE_RECONNECTING,                 /* auth */
        USB_STATE_UNAUTHENTICATED,              /* auth */
        USB_STATE_DEFAULT,                      /* limited function */
        USB_STATE_ADDRESS,
        USB_STATE_CONFIGURED,                   /* most functions */

        USB_STATE_SUSPENDED

        /* NOTE:  there are actually four different SUSPENDED
         * states, returning to POWERED, DEFAULT, ADDRESS, or
         * CONFIGURED respectively when SOF tokens flow again.
         * At this level there's no difference between L1 and L2
         * suspend states.  (L2 being original USB 1.1 suspend.)
         */
};