USB: Add macros for interrupt endpoint types.

The USB 3.0 spec defines a new way of differentiating interrupt
endpoints. The idea is that some interrupt endpoints are used for
notifications, i.e. they continually NAK the transfer until something
changes on the device. Other interrupt endpoints are used as a way to
periodically transfer data.

The USB 3.0 endpoint descriptor uses bits 5:4 of bmAttributes for
interrupt endpoints, to define the endpoint as either a Notification
endpoint, or a Periodic endpoint. Introduce macros to dig out that
information.

Signed-off-by: Sarah Sharp <[e-mail]>

include/linux/usb/ch9.h

···
 #define USB_ENDPOINT_XFER_INT		3
 #define USB_ENDPOINT_MAX_ADJUSTABLE	0x80
 
+/* The USB 3.0 spec redefines bits 5:4 of bmAttributes as interrupt ep type. */
+#define USB_ENDPOINT_INTRTYPE		0x30
+#define USB_ENDPOINT_INTR_PERIODIC	(0 << 4)
+#define USB_ENDPOINT_INTR_NOTIFICATION	(1 << 4)
+
 #define USB_ENDPOINT_SYNCTYPE		0x0c
 #define USB_ENDPOINT_SYNC_NONE		(0 << 2)
 #define USB_ENDPOINT_SYNC_ASYNC		(1 << 2)
···
 static inline int usb_endpoint_maxp(const struct usb_endpoint_descriptor *epd)
 {
 	return __le16_to_cpu(epd->wMaxPacketSize);
+}
+
+static inline int usb_endpoint_interrupt_type(
+		const struct usb_endpoint_descriptor *epd)
+{
+	return epd->bmAttributes & USB_ENDPOINT_INTRTYPE;
 }
 
 /*-------------------------------------------------------------------------*/