usb: dwc3: debugfs: Properly print/set link state for HS

Highspeed device and below has different state names than superspeed and
higher. Add proper checks and printouts of link states for highspeed and
below.

Signed-off-by: Thinh Nguyen <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/dwc3/debug.h

···
 }
 
 /**
+ * dwc3_gadget_hs_link_string - returns highspeed and below link name
+ * @link_state: link state code
+ */
+static inline const char *
+dwc3_gadget_hs_link_string(enum dwc3_link_state link_state)
+{
+	switch (link_state) {
+	case DWC3_LINK_STATE_U0:
+		return "On";
+	case DWC3_LINK_STATE_U2:
+		return "Sleep";
+	case DWC3_LINK_STATE_U3:
+		return "Suspend";
+	case DWC3_LINK_STATE_SS_DIS:
+		return "Disconnected";
+	case DWC3_LINK_STATE_RX_DET:
+		return "Early Suspend";
+	case DWC3_LINK_STATE_RECOV:
+		return "Recovery";
+	case DWC3_LINK_STATE_RESET:
+		return "Reset";
+	case DWC3_LINK_STATE_RESUME:
+		return "Resume";
+	default:
+		return "UNKNOWN link state\n";
+	}
+}
+
+/**
  * dwc3_trb_type_string - returns TRB type as a string
  * @type: the type of the TRB
  */

drivers/usb/dwc3/debugfs.c

···
 	unsigned long		flags;
 	enum dwc3_link_state	state;
 	u32			reg;
+	u8			speed;
 
 	spin_lock_irqsave(&dwc->lock, flags);
 	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
 	state = DWC3_DSTS_USBLNKST(reg);
-	spin_unlock_irqrestore(&dwc->lock, flags);
+	speed = reg & DWC3_DSTS_CONNECTSPD;
 
-	seq_printf(s, "%s\n", dwc3_gadget_link_string(state));
+	seq_printf(s, "%s\n", (speed >= DWC3_DSTS_SUPERSPEED) ?
+		   dwc3_gadget_link_string(state) :
+		   dwc3_gadget_hs_link_string(state));
+	spin_unlock_irqrestore(&dwc->lock, flags);
 
 	return 0;
 }
···
 	unsigned long		flags;
 	enum dwc3_link_state	state = 0;
 	char			buf[32];
+	u32			reg;
+	u8			speed;
 
 	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
 		return -EFAULT;
···
 		return -EINVAL;
 
 	spin_lock_irqsave(&dwc->lock, flags);
+	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
+	speed = reg & DWC3_DSTS_CONNECTSPD;
+
+	if (speed < DWC3_DSTS_SUPERSPEED &&
+	    state != DWC3_LINK_STATE_RECOV) {
+		spin_unlock_irqrestore(&dwc->lock, flags);
+		return -EINVAL;
+	}
+
 	dwc3_gadget_set_link_state(dwc, state);
 	spin_unlock_irqrestore(&dwc->lock, flags);