xhci: use pm_ptr() instead of #ifdef for CONFIG_PM conditionals

A recent patch caused an unused-function warning in builds with
CONFIG_PM disabled, after the function became marked 'static':

drivers/usb/host/xhci-pci.c:91:13: error: 'xhci_msix_sync_irqs' defined but not used [-Werror=unused-function]
   91 | static void xhci_msix_sync_irqs(struct xhci_hcd *xhci)
      |             ^~~~~~~~~~~~~~~~~~~

This could be solved by adding another #ifdef, but as there is
a trend towards removing CONFIG_PM checks in favor of helper
macros, do the same conversion here and use pm_ptr() to get
either a function pointer or NULL but avoid the warning.

As the hidden functions reference some other symbols, make
sure those are visible at compile time, at the minimal cost of
a few extra bytes for 'struct usb_device'.

Fixes: 9abe15d5 ("xhci: Move xhci MSI sync function to to xhci-pci")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230328131114.1296430-1-arnd@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-pci.c

@@ -728,7 +728,6 @@ static void xhci_pci_remove(struct pci_dev *dev)
 	usb_hcd_pci_remove(dev);
 }
 
-#ifdef CONFIG_PM
 /*
  * In some Intel xHCI controllers, in order to get D3 working,
  * through a vendor specific SSIC CONFIG register at offset 0x883c,
@@ -927,7 +926,6 @@ static void xhci_pci_shutdown(struct usb_hcd *hcd)
 	if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
 		pci_set_power_state(pdev, PCI_D3hot);
 }
-#endif /* CONFIG_PM */
 
 /*-------------------------------------------------------------------------*/
 
@@ -970,9 +968,7 @@ static struct pci_driver xhci_pci_driver = {
 
 	.shutdown = 	usb_hcd_pci_shutdown,
 	.driver = {
-#ifdef CONFIG_PM
-		.pm = &usb_hcd_pci_pm_ops,
-#endif
+		.pm = pm_ptr(&usb_hcd_pci_pm_ops),
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 	},
 };
@@ -980,12 +976,10 @@ static struct pci_driver xhci_pci_driver = {
 static int __init xhci_pci_init(void)
 {
 	xhci_init_driver(&xhci_pci_hc_driver, &xhci_pci_overrides);
-#ifdef CONFIG_PM
-	xhci_pci_hc_driver.pci_suspend = xhci_pci_suspend;
-	xhci_pci_hc_driver.pci_resume = xhci_pci_resume;
-	xhci_pci_hc_driver.pci_poweroff_late = xhci_pci_poweroff_late;
-	xhci_pci_hc_driver.shutdown = xhci_pci_shutdown;
-#endif
+	xhci_pci_hc_driver.pci_suspend = pm_ptr(xhci_pci_suspend);
+	xhci_pci_hc_driver.pci_resume = pm_ptr(xhci_pci_resume);
+	xhci_pci_hc_driver.pci_poweroff_late = pm_ptr(xhci_pci_poweroff_late);
+	xhci_pci_hc_driver.shutdown = pm_ptr(xhci_pci_shutdown);
 	xhci_pci_hc_driver.stop = xhci_pci_stop;
 	return pci_register_driver(&xhci_pci_driver);
 }

include/linux/usb.h

@@ -704,13 +704,12 @@ struct usb_device {
 
 	unsigned long active_duration;
 
-#ifdef CONFIG_PM
 	unsigned long connect_time;
 
 	unsigned do_remote_wakeup:1;
 	unsigned reset_resume:1;
 	unsigned port_is_suspended:1;
-#endif
+
 	struct wusb_dev *wusb_dev;
 	int slot_id;
 	struct usb2_lpm_parameters l1_params;

include/linux/usb/hcd.h

@@ -488,9 +488,7 @@ extern void usb_hcd_pci_shutdown(struct pci_dev *dev);
 
 extern int usb_hcd_amd_remote_wakeup_quirk(struct pci_dev *dev);
 
-#ifdef CONFIG_PM
 extern const struct dev_pm_ops usb_hcd_pci_pm_ops;
-#endif
 #endif /* CONFIG_USB_PCI */
 
 /* pci-ish (pdev null is ok) buffer alloc/mapping support */