usb: gadget: Introduce udc_set_ssp_rate() for SSP

A SuperSpeed Plus device may operate at different speed and lane count
(i.e. gen2x2, gen1x2, or gen2x1). Introduce gadget ops
udc_set_ssp_rate() to set the desire corresponding usb_ssp_rate for
SuperSpeed Plus capable devices.

If the USB device supports different speeds at SuperSpeed Plus, set the
device to operate with the maximum number of lanes and speed.

Signed-off-by: Thinh Nguyen <[e-mail]>
Link: https://lore.kernel.org/r/9b85[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/udc/core.c

···
 static inline void usb_gadget_udc_set_speed(struct usb_udc *udc,
 					    enum usb_device_speed speed)
 {
-	if (udc->gadget->ops->udc_set_speed) {
-		enum usb_device_speed s;
+	struct usb_gadget *gadget = udc->gadget;
+	enum usb_device_speed s;
 
-		s = min(speed, udc->gadget->max_speed);
-		udc->gadget->ops->udc_set_speed(udc->gadget, s);
-	}
+	if (speed == USB_SPEED_UNKNOWN)
+		s = gadget->max_speed;
+	else
+		s = min(speed, gadget->max_speed);
+
+	if (s == USB_SPEED_SUPER_PLUS && gadget->ops->udc_set_ssp_rate)
+		gadget->ops->udc_set_ssp_rate(gadget, gadget->max_ssp_rate);
+	else if (gadget->ops->udc_set_speed)
+		gadget->ops->udc_set_speed(gadget, s);
 }
 
 /**

include/linux/usb/gadget.h

···
 			struct usb_gadget_driver *);
 	int	(*udc_stop)(struct usb_gadget *);
 	void	(*udc_set_speed)(struct usb_gadget *, enum usb_device_speed);
+	void	(*udc_set_ssp_rate)(struct usb_gadget *gadget,
+			enum usb_ssp_rate rate);
 	struct usb_ep *(*match_ep)(struct usb_gadget *,
 			struct usb_endpoint_descriptor *,
 			struct usb_ss_ep_comp_descriptor *);