usb: dwc3: gadget: Introduce a DWC3 VBUS draw callback

Some devices support charging while in device mode.  In these situations,
the USB gadget will notify the DWC3 gadget driver to modify the current
based on the enumeration and device state.  The usb_phy_set_power() API
will allow external charger entities to adjust the charge current through
the notifier block.
Reviewed-by: NPeter Chen <peter.chen@nxp.com>
Signed-off-by: NWesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/1609283011-21997-2-git-send-email-wcheng@codeaurora.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/gadget.c

@@ -2463,6 +2463,16 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
 	spin_unlock_irqrestore(&dwc->lock, flags);
 }
 
+static int dwc3_gadget_vbus_draw(struct usb_gadget *g, unsigned int mA)
+{
+	struct dwc3		*dwc = gadget_to_dwc(g);
+
+	if (dwc->usb2_phy)
+		return usb_phy_set_power(dwc->usb2_phy, mA);
+
+	return 0;
+}
+
 static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.get_frame		= dwc3_gadget_get_frame,
 	.wakeup			= dwc3_gadget_wakeup,
@@ -2472,6 +2482,7 @@ static const struct usb_gadget_ops dwc3_gadget_ops = {
 	.udc_stop		= dwc3_gadget_stop,
 	.udc_set_speed		= dwc3_gadget_set_speed,
 	.get_config_params	= dwc3_gadget_config_params,
+	.vbus_draw		= dwc3_gadget_vbus_draw,
 };
 
 /* -------------------------------------------------------------------------- */