usb: Add tunnel_mode parameter to usb device structure

Add 'tunnel_mode' enum to usb device structure to describe if a USB3
link is tunneled over USB4, or connected directly using native USB2/USB3
protocols.

Tunneled devices depend on USB4 NHI host to maintain the tunnel.
Knowledge about tunneled devices is important to ensure correct
suspend and resume order between USB4 hosts and tunneled devices.
i.e. make sure tunnel is up before the USB device using it resumes.

USB hosts such as xHCI may have vendor specific ways to detect tunneled
connections. This 'tunnel_mode' parameter can be set by USB3 host driver
during hcd->driver->update_device(hcd, udev) callback.

tunnel_mode can be set to:
USB_LINK_UNKNOWN = 0
USB_LINK_NATIVE
USB_LINK_TUNNELED

USB_LINK_UNKNOWN is used in case host is not capable of detecting
tunneled links.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20240830152630.3943215-3-mathias.nyman@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-hub.c

@@ -763,9 +763,12 @@ static int xhci_exit_test_mode(struct xhci_hcd *xhci)
  *
  * A USB3 device must be connected to the port to detect the tunnel.
  *
- * Return: true if USB3 connection is tunneled over USB4
+ * Return: link tunnel mode enum, USB_LINK_UNKNOWN if host is incapable of
+ * detecting USB3 over USB4 tunnels. USB_LINK_NATIVE or USB_LINK_TUNNELED
+ * otherwise.
  */
-bool xhci_port_is_tunneled(struct xhci_hcd *xhci, struct xhci_port *port)
+enum usb_link_tunnel_mode xhci_port_is_tunneled(struct xhci_hcd *xhci,
+						struct xhci_port *port)
 {
 	void __iomem *base;
 	u32 offset;
@@ -777,10 +780,12 @@ bool xhci_port_is_tunneled(struct xhci_hcd *xhci, struct xhci_port *port)
 		offset = XHCI_INTEL_SPR_ESS_PORT_OFFSET + port->hcd_portnum * 0x20;
 
 		if (readl(base + offset) & XHCI_INTEL_SPR_TUNEN)
-			return true;
+			return USB_LINK_TUNNELED;
+		else
+			return USB_LINK_NATIVE;
 	}
 
-	return false;
+	return USB_LINK_UNKNOWN;
 }
 
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,

drivers/usb/host/xhci.c

@@ -4529,9 +4529,12 @@ static int xhci_update_device(struct usb_hcd *hcd, struct usb_device *udev)
 	if (hcd->speed >= HCD_USB3 && !udev->parent->parent) {
 		port = xhci->usb3_rhub.ports[udev->portnum - 1];
 
-		if (xhci_port_is_tunneled(xhci, port))
+		udev->tunnel_mode = xhci_port_is_tunneled(xhci, port);
+		if (udev->tunnel_mode == USB_LINK_UNKNOWN)
+			dev_dbg(&udev->dev, "link tunnel state unknown\n");
+		else if (udev->tunnel_mode == USB_LINK_TUNNELED)
 			dev_dbg(&udev->dev, "tunneled over USB4 link\n");
-		else
+		else if (udev->tunnel_mode == USB_LINK_NATIVE)
 			dev_dbg(&udev->dev, "native USB 3.x link\n");
 		return 0;
 	}

drivers/usb/host/xhci.h

@@ -1929,8 +1929,8 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue, u16 wIndex,
 int xhci_hub_status_data(struct usb_hcd *hcd, char *buf);
 int xhci_find_raw_port_number(struct usb_hcd *hcd, int port1);
 struct xhci_hub *xhci_get_rhub(struct usb_hcd *hcd);
-bool xhci_port_is_tunneled(struct xhci_hcd *xhci, struct xhci_port *port);
-
+enum usb_link_tunnel_mode xhci_port_is_tunneled(struct xhci_hcd *xhci,
+						struct xhci_port *port);
 void xhci_hc_died(struct xhci_hcd *xhci);
 
 #ifdef CONFIG_PM

include/linux/usb.h

@@ -495,6 +495,12 @@ struct usb_dev_state;
 
 struct usb_tt;
 
+enum usb_link_tunnel_mode {
+	USB_LINK_UNKNOWN = 0,
+	USB_LINK_NATIVE,
+	USB_LINK_TUNNELED,
+};
+
 enum usb_port_connect_type {
 	USB_PORT_CONNECT_TYPE_UNKNOWN = 0,
 	USB_PORT_CONNECT_TYPE_HOT_PLUG,
@@ -605,6 +611,7 @@ struct usb3_lpm_parameters {
  *	WUSB devices are not, until we authorize them from user space.
  *	FIXME -- complete doc
  * @authenticated: Crypto authentication passed
+ * @tunnel_mode: Connection native or tunneled over USB4
  * @lpm_capable: device supports LPM
  * @lpm_devinit_allow: Allow USB3 device initiated LPM, exit latency is in range
  * @usb2_hw_lpm_capable: device can perform USB2 hardware LPM
@@ -714,6 +721,7 @@ struct usb_device {
 	unsigned do_remote_wakeup:1;
 	unsigned reset_resume:1;
 	unsigned port_is_suspended:1;
+	enum usb_link_tunnel_mode tunnel_mode;
 
 	int slot_id;
 	struct usb2_lpm_parameters l1_params;