xhci: Workaround for PME stuck issues in Intel xhci

commit b8cb91e0 upstream.

The xhci in Intel Sunrisepoint and Cherryview platforms need a driver
workaround for a Stuck PME that might either block PME events in suspend,
or create spurious PME events preventing runtime suspend.

Workaround is to clear a internal PME flag, BIT(28) in a vendor specific
PMCTRL register at offset 0x80a4, in both suspend resume callbacks

Without this, xhci connected usb devices might never be able to wake up the
system from suspend, or prevent device from going to suspend (xhci d3)
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/host/xhci-pci.c

@@ -36,6 +36,9 @@
 
 #define PCI_DEVICE_ID_INTEL_LYNXPOINT_XHCI	0x8c31
 #define PCI_DEVICE_ID_INTEL_LYNXPOINT_LP_XHCI	0x9c31
+#define PCI_DEVICE_ID_INTEL_CHERRYVIEW_XHCI		0x22b5
+#define PCI_DEVICE_ID_INTEL_SUNRISEPOINT_H_XHCI		0xa12f
+#define PCI_DEVICE_ID_INTEL_SUNRISEPOINT_LP_XHCI	0x9d2f
 
 static const char hcd_name[] = "xhci_hcd";
 
@@ -118,6 +121,12 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		xhci->quirks |= XHCI_SPURIOUS_REBOOT;
 		xhci->quirks |= XHCI_AVOID_BEI;
 	}
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
+		(pdev->device == PCI_DEVICE_ID_INTEL_SUNRISEPOINT_LP_XHCI ||
+		 pdev->device == PCI_DEVICE_ID_INTEL_SUNRISEPOINT_H_XHCI ||
+		 pdev->device == PCI_DEVICE_ID_INTEL_CHERRYVIEW_XHCI)) {
+		xhci->quirks |= XHCI_PME_STUCK_QUIRK;
+	}
 	if (pdev->vendor == PCI_VENDOR_ID_ETRON &&
 			pdev->device == PCI_DEVICE_ID_ASROCK_P67) {
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
@@ -128,6 +137,21 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
 }
 
+/*
+ * Make sure PME works on some Intel xHCI controllers by writing 1 to clear
+ * the Internal PME flag bit in vendor specific PMCTRL register at offset 0x80a4
+ */
+static void xhci_pme_quirk(struct xhci_hcd *xhci)
+{
+	u32 val;
+	void __iomem *reg;
+
+	reg = (void __iomem *) xhci->cap_regs + 0x80a4;
+	val = readl(reg);
+	writel(val | BIT(28), reg);
+	readl(reg);
+}
+
 /* called during probe() after chip reset completes */
 static int xhci_pci_setup(struct usb_hcd *hcd)
 {
@@ -235,6 +259,9 @@ static int xhci_pci_suspend(struct usb_hcd *hcd, bool do_wakeup)
 			xhci->shared_hcd->state != HC_STATE_SUSPENDED)
 		return -EINVAL;
 
+	if (xhci->quirks & XHCI_PME_STUCK_QUIRK)
+		xhci_pme_quirk(xhci);
+
 	retval = xhci_suspend(xhci, do_wakeup);
 
 	return retval;
@@ -265,6 +292,9 @@ static int xhci_pci_resume(struct usb_hcd *hcd, bool hibernated)
 	if (usb_is_intel_switchable_xhci(pdev))
 		usb_enable_xhci_ports(pdev);
 
+	if (xhci->quirks & XHCI_PME_STUCK_QUIRK)
+		xhci_pme_quirk(xhci);
+
 	retval = xhci_resume(xhci, hibernated);
 	return retval;
 }

drivers/usb/host/xhci.h

@@ -1497,6 +1497,7 @@ struct xhci_hcd {
 #define XHCI_AVOID_BEI		(1 << 15)
 #define XHCI_SLOW_SUSPEND	(1 << 17)
 #define XHCI_SPURIOUS_WAKEUP	(1 << 18)
+#define XHCI_PME_STUCK_QUIRK	(1 << 20)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */