From 868dd50c5c24f4851cf699c471dcc3c96623e91b Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Thu, 15 Aug 2024 17:17:05 +0000
Subject: [PATCH] Upon resume, restore the saved state.  Newer Intel xHCI
 controller (e.g. those on Meteor Lake) need this, otherwise the ports are
 dead after resume.

ok mglocker@, deraadt@
---
 sys/dev/usb/xhci.c    | 30 +++++++++++++++++++++++++-----
 sys/dev/usb/xhcivar.h |  3 ++-
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/sys/dev/usb/xhci.c b/sys/dev/usb/xhci.c
index e2ca8e8056d..75792693b70 100644
--- a/sys/dev/usb/xhci.c
+++ b/sys/dev/usb/xhci.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: xhci.c,v 1.132 2024/08/06 17:30:04 kettenis Exp $ */
+/* $OpenBSD: xhci.c,v 1.133 2024/08/15 17:17:05 kettenis Exp $ */
 
 /*
  * Copyright (c) 2014-2015 Martin Pieuchot
@@ -415,6 +415,7 @@ xhci_config(struct xhci_softc *sc)
 {
 	uint64_t paddr;
 	uint32_t hcr;
+	int i;
 
 	/* Make sure to program a number of device slots we can handle. */
 	if (sc->sc_noslot > USB_MAX_DEVICES)
@@ -457,6 +458,27 @@ xhci_config(struct xhci_softc *sc)
 	DPRINTF(("%s: ERDP=%#x%#x\n", DEVNAME(sc),
 	    XRREAD4(sc, XHCI_ERDP_HI(0)), XRREAD4(sc, XHCI_ERDP_LO(0))));
 
+	/*
+	 * If we successfully saved the state during suspend, restore
+	 * it here.  Otherwise some Intel controllers don't function
+	 * correctly after resume.
+	 */
+	if (sc->sc_saved_state) {
+		XOWRITE4(sc, XHCI_USBCMD, XHCI_CMD_CRS); /* Restore state */
+		hcr = XOREAD4(sc, XHCI_USBSTS);
+		for (i = 0; i < 100; i++) {
+			usb_delay_ms(&sc->sc_bus, 1);
+			hcr = XOREAD4(sc, XHCI_USBSTS) & XHCI_STS_RSS;
+			if (!hcr)
+				break;
+		}
+
+		if (hcr)
+			printf("%s: restore state timeout\n", DEVNAME(sc));
+
+		sc->sc_saved_state = 0;
+	}
+
 	/* Enable interrupts. */
 	hcr = XRREAD4(sc, XHCI_IMAN(0));
 	XRWRITE4(sc, XHCI_IMAN(0), hcr | XHCI_IMAN_INTR_ENA);
@@ -603,10 +625,6 @@ xhci_suspend(struct xhci_softc *sc)
 	 * unless they have seen a save state command.  This in turn
 	 * will prevent the SoC from reaching its lowest idle state.
 	 * So save the state here.
-	 *
-	 * Note that we don't restore this saved state anywhere.
-	 * Instead we reset the controller and reinitialize it from
-	 * scratch when we resume.
 	 */
 
 	XOWRITE4(sc, XHCI_USBCMD, XHCI_CMD_CSS); /* Save state */
@@ -624,6 +642,8 @@ xhci_suspend(struct xhci_softc *sc)
 		return;
 	}
 
+	sc->sc_saved_state = 1;
+
 	/* Disable interrupts. */
 	XRWRITE4(sc, XHCI_IMOD(0), 0);
 	XRWRITE4(sc, XHCI_IMAN(0), 0);
diff --git a/sys/dev/usb/xhcivar.h b/sys/dev/usb/xhcivar.h
index d1a4a831389..cf1e86feb56 100644
--- a/sys/dev/usb/xhcivar.h
+++ b/sys/dev/usb/xhcivar.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: xhcivar.h,v 1.14 2022/12/12 19:18:25 kettenis Exp $ */
+/* $OpenBSD: xhcivar.h,v 1.15 2024/08/15 17:17:05 kettenis Exp $ */
 
 /*
  * Copyright (c) 2014 Martin Pieuchot
@@ -89,6 +89,7 @@ struct xhci_softc {
 	bus_size_t		 sc_size;
 
 	int			 sc_dead;
+	int			 sc_saved_state;
 
 	bus_size_t		 sc_oper_off;	/* Operational Register space */
 	bus_size_t		 sc_runt_off;	/* Runtime */
-- 
2.20.1