[xhci] Undo PCH-specific quirk fixes when removing device

Restore the original values of XUSB2PR and USB3PSSEN, in case we are
booting an OS with no support for xHCI.

Suggested-by: Dan Ellis <Dan.Ellis@displaylink.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/usb/xhci.c

  * @v xhci		xHCI device
  * @v pci		PCI device
  */
-static void xhci_pch ( struct xhci_device *xhci, struct pci_device *pci ) {
+static void xhci_pch_fix ( struct xhci_device *xhci, struct pci_device *pci ) {
+	struct xhci_pch *pch = &xhci->pch;
 	uint32_t xusb2pr;
 	uint32_t xusb2prm;
 	uint32_t usb3pssen;
 		DBGC ( xhci, "XHCI %p enabling SuperSpeed on ports %08x\n",
 		       xhci, ( usb3prm & ~usb3pssen ) );
 	}
+	pch->usb3pssen = usb3pssen;
 	usb3pssen |= usb3prm;
 	pci_write_config_dword ( pci, XHCI_PCH_USB3PSSEN, usb3pssen );
 
 		DBGC ( xhci, "XHCI %p routing ports %08x from EHCI to xHCI\n",
 		       xhci, ( xusb2prm & ~xusb2pr ) );
 	}
+	pch->xusb2pr = xusb2pr;
 	xusb2pr |= xusb2prm;
 	pci_write_config_dword ( pci, XHCI_PCH_XUSB2PR, xusb2pr );
 }
 
+/**
+ * Undo Intel PCH-specific quirk fixes
+ *
+ * @v xhci		xHCI device
+ * @v pci		PCI device
+ */
+static void xhci_pch_undo ( struct xhci_device *xhci, struct pci_device *pci ) {
+	struct xhci_pch *pch = &xhci->pch;
+
+	/* Restore USB2 port routing to original state */
+	pci_write_config_dword ( pci, XHCI_PCH_XUSB2PR, pch->xusb2pr );
+
+	/* Restore SuperSpeed capability to original state */
+	pci_write_config_dword ( pci, XHCI_PCH_USB3PSSEN, pch->usb3pssen );
+}
+
 /**
  * Probe PCI device
  *
 
 	/* Fix Intel PCH-specific quirks, if applicable */
 	if ( pci->id->driver_data & XHCI_PCH )
-		xhci_pch ( xhci, pci );
+		xhci_pch_fix ( xhci, pci );
 
 	/* Reset device */
 	if ( ( rc = xhci_reset ( xhci ) ) != 0 )
  err_alloc_bus:
 	xhci_reset ( xhci );
  err_reset:
+	if ( pci->id->driver_data & XHCI_PCH )
+		xhci_pch_undo ( xhci, pci );
 	xhci_legacy_release ( xhci );
  err_legacy_claim:
 	iounmap ( xhci->regs );
 	unregister_usb_bus ( bus );
 	free_usb_bus ( bus );
 	xhci_reset ( xhci );
+	if ( pci->id->driver_data & XHCI_PCH )
+		xhci_pch_undo ( xhci, pci );
 	xhci_legacy_release ( xhci );
 	iounmap ( xhci->regs );
 	free ( xhci );

src/drivers/usb/xhci.h

  */
 #define XHCI_PORT_RESET_MAX_WAIT_MS 500
 
+/** Intel PCH quirk */
+struct xhci_pch {
+	/** USB2 port routing register original value */
+	uint32_t xusb2pr;
+	/** USB3 port SuperSpeed enable register original value */
+	uint32_t usb3pssen;
+};
+
+/** Intel PCH quirk flag */
+#define XHCI_PCH 0x0001
+
+/** Intel PCH USB2 port routing register */
+#define XHCI_PCH_XUSB2PR 0xd0
+
+/** Intel PCH USB2 port routing mask register */
+#define XHCI_PCH_XUSB2PRM 0xd4
+
+/** Intel PCH SuperSpeed enable register */
+#define XHCI_PCH_USB3PSSEN 0xd8
+
+/** Intel PCH USB3 port routing mask register */
+#define XHCI_PCH_USB3PRM 0xdc
+
 /** An xHCI device */
 struct xhci_device {
 	/** Registers */
 
 	/** USB bus */
 	struct usb_bus *bus;
+
+	/** Intel PCH quirk */
+	struct xhci_pch pch;
 };
 
 /** An xHCI device slot */
 	struct xhci_trb_ring ring;
 };
 
-/** Intel PCH quirk */
-#define XHCI_PCH 0x0001
-
-/** Intel PCH USB2 port routing register */
-#define XHCI_PCH_XUSB2PR 0xd0
-
-/** Intel PCH USB2 port routing mask register */
-#define XHCI_PCH_XUSB2PRM 0xd4
-
-/** Intel PCH USB3 port SuperSpeed enable register */
-#define XHCI_PCH_USB3PSSEN 0xd8
-
-/** Intel PCH USB3 port routing mask register */
-#define XHCI_PCH_USB3PRM 0xdc
-
 #endif /* _IPXE_XHCI_H */