xhci: rework how real & fake ports are found

xHC hardware needs to know which roothub port a USB device is attached to
when controlling the device, so the xHCI driver stores in each device the
roothub port which it's connected behind. This is done with two different
port index values, the 'real_port' which is an index to the xHC hardware
port register array, and the 'fake_port' which is the per hub port index
used by the hub driver.

Instead of finding real & fake port separately, find the root hub port
'xhci_port' structure which contains both real & fake port values:
- 'real_port' is ('hw_portnum' + 1)
- 'fake_port' is ('hcd_portnum' + 1)
i.e. real & fake port are 'hw_portnum' & 'hcd_portnum' in one-based
format.

The 'xhci_port' structure is a better way to refer to roothub ports than
the 'real_port' & 'fake_port'. As a result, these port indexes are slated
to be replaced with a direct pointer to the root hub port. This patch
setups the ground work for the future changes.

Signed-off-by: Niklas Neronin <[e-mail]>
Signed-off-by: Mathias Nyman <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci-mem.c

···
  * The xHCI roothub may have ports of differing speeds in any order in the port
  * status registers.
  *
- * The xHCI hardware wants to know the roothub port number that the USB device
+ * The xHCI hardware wants to know the roothub port that the USB device
  * is attached to (or the roothub port its ancestor hub is attached to).  All we
  * know is the index of that port under either the USB 2.0 or the USB 3.0
  * roothub, but that doesn't give us the real index into the HW port status
- * registers. Call xhci_find_raw_port_number() to get real index.
+ * registers.
  */
-static u32 xhci_find_real_port_number(struct xhci_hcd *xhci,
-		struct usb_device *udev)
+static struct xhci_port *xhci_find_rhub_port(struct xhci_hcd *xhci, struct usb_device *udev)
 {
 	struct usb_device *top_dev;
+	struct xhci_hub *rhub;
 	struct usb_hcd *hcd;
 
 	if (udev->speed >= USB_SPEED_SUPER)
···
 			top_dev = top_dev->parent)
 		/* Found device below root hub */;
 
-	return	xhci_find_raw_port_number(hcd, top_dev->portnum);
+	rhub = xhci_get_rhub(hcd);
+	return rhub->ports[top_dev->portnum - 1];
 }
 
 /* Setup an xHCI virtual device for a Set Address command */
···
 	struct xhci_virt_device *dev;
 	struct xhci_ep_ctx	*ep0_ctx;
 	struct xhci_slot_ctx    *slot_ctx;
-	u32			port_num;
+	struct xhci_port	*rhub_port;
 	u32			max_packets;
-	struct usb_device *top_dev;
 
 	dev = xhci->devs[udev->slot_id];
 	/* Slot ID 0 is reserved */
···
 		return -EINVAL;
 	}
 	/* Find the root hub port this device is under */
-	port_num = xhci_find_real_port_number(xhci, udev);
-	if (!port_num)
+	rhub_port = xhci_find_rhub_port(xhci, udev);
+	if (!rhub_port)
 		return -EINVAL;
-	slot_ctx->dev_info2 |= cpu_to_le32(ROOT_HUB_PORT(port_num));
-	/* Set the port number in the virtual_device to the faked port number */
-	for (top_dev = udev; top_dev->parent && top_dev->parent->parent;
-			top_dev = top_dev->parent)
-		/* Found device below root hub */;
-	dev->fake_port = top_dev->portnum;
-	dev->real_port = port_num;
-	xhci_dbg(xhci, "Set root hub portnum to %d\n", port_num);
+	dev->real_port = rhub_port->hw_portnum + 1;
+	dev->fake_port = rhub_port->hcd_portnum + 1;
+	slot_ctx->dev_info2 |= cpu_to_le32(ROOT_HUB_PORT(dev->real_port));
+	xhci_dbg(xhci, "Set root hub portnum to %d\n", dev->real_port);
 	xhci_dbg(xhci, "Set fake root hub portnum to %d\n", dev->fake_port);
 
 	/* Find the right bandwidth table that this device will be a part of.
···
 	 * will never be created for the HS root hub.
 	 */
 	if (!udev->tt || !udev->tt->hub->parent) {
-		dev->bw_table = &xhci->rh_bw[port_num - 1].bw_table;
+		dev->bw_table = &xhci->rh_bw[dev->real_port - 1].bw_table;
 	} else {
 		struct xhci_root_port_bw_info *rh_bw;
 		struct xhci_tt_bw_info *tt_bw;
 
-		rh_bw = &xhci->rh_bw[port_num - 1];
+		rh_bw = &xhci->rh_bw[dev->real_port - 1];
 		/* Find the right TT. */
 		list_for_each_entry(tt_bw, &rh_bw->tts, tt_list) {
 			if (tt_bw->slot_id != udev->tt->hub->slot_id)