usb: dwc3: gadget: implement dwc3_gadget_get_link_state

This function will be used during hibernation to get
the current link state. It will be needed at least
for Hibernation support.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 7f4e6dd..7d00738 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -68,6 +68,22 @@
 }
 
 /**
+ * dwc3_gadget_get_link_state - Gets current state of USB Link
+ * @dwc: pointer to our context structure
+ *
+ * Caller should take care of locking. This function will
+ * return the link state on success (>= 0) or -ETIMEDOUT.
+ */
+int dwc3_gadget_get_link_state(struct dwc3 *dwc)
+{
+	u32		reg;
+
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+
+	return DWC3_DSTS_USBLNKST(reg);
+}
+
+/**
  * dwc3_gadget_set_link_state - Sets USB Link to a particular State
  * @dwc: pointer to our context structure
  * @state: the state to put link into