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.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 16 insertions, 8 deletions

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 4ba910eadd3f..d27c30ac17fd 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/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,
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 1ea2c91106b7..a69245074395 100644
--- a/drivers/usb/host/xhci.c
+++ b/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;
 	}
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index e87a6b2f139d..40aebdfb37c9 100644
--- a/drivers/usb/host/xhci.h
+++ b/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