USB: Fix ehci infinite suspend-resume loop issue in zhaoxin

In zhaoxin platform, some ehci projects will latch a wakeup signal
internal when plug in a device on port during system S0. This wakeup
signal will turn on when ehci runtime suspend, which will trigger a
system control interrupt that will resume ehci back to D0. As no
device connect, ehci will be set to runtime suspend and turn on the
internal latched wakeup signal again. It will cause a suspend-resume
loop and generate system control interrupt continuously.

Fixed this issue by clear wakeup signal latched in ehci internal when
ehci resume callback is called.

Acked-by: Alan Stern <[e-mail]>
Signed-off-by: Weitao Wang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-hcd.c

···
 
 #ifdef	CONFIG_PM
 
+/* Clear wakeup signal locked in zhaoxin platform when device plug in. */
+static void ehci_zx_wakeup_clear(struct ehci_hcd *ehci)
+{
+	u32 __iomem	*reg = &ehci->regs->port_status[4];
+	u32 		t1 = ehci_readl(ehci, reg);
+
+	t1 &= (u32)~0xf0000;
+	t1 |= PORT_TEST_FORCE;
+	ehci_writel(ehci, t1, reg);
+	t1 = ehci_readl(ehci, reg);
+	msleep(1);
+	t1 &= (u32)~0xf0000;
+	ehci_writel(ehci, t1, reg);
+	ehci_readl(ehci, reg);
+	msleep(1);
+	t1 = ehci_readl(ehci, reg);
+	ehci_writel(ehci, t1 | PORT_CSC, reg);
+	ehci_readl(ehci, reg);
+}
+
 /* suspend/resume, section 4.3 */
 
 /* These routines handle the generic parts of controller suspend/resume */
···
 
 	if (ehci->shutdown)
 		return 0;		/* Controller is dead */
+
+	if (ehci->zx_wakeup_clear_needed)
+		ehci_zx_wakeup_clear(ehci);
 
 	/*
 	 * If CF is still set and reset isn't forced

drivers/usb/host/ehci-pci.c

···
 			ehci->is_aspeed = 1;
 		}
 		break;
+	case PCI_VENDOR_ID_ZHAOXIN:
+		if (pdev->device == 0x3104 && (pdev->revision & 0xf0) == 0x90)
+			ehci->zx_wakeup_clear_needed = 1;
+		break;
 	}
 
 	/* optional debug port, normally in the first BAR */

drivers/usb/host/ehci.h

···
 	unsigned		imx28_write_fix:1; /* For Freescale i.MX28 */
 	unsigned		spurious_oc:1;
 	unsigned		is_aspeed:1;
+	unsigned		zx_wakeup_clear_needed:1;
 
 	/* required for usb32 quirk */
 	#define OHCI_CTRL_HCFS          (3 << 6)