powerpc/usb: fix issue of CPU halt when missing USB PHY clock

when missing USB PHY clock, kernel booting up will halt during USB
initialization. We should check USBGP[PHY_CLK_VALID] bit to avoid
CPU hang in this case.
Signed-off-by: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-fsl.c

@@ -239,7 +239,7 @@ static void ehci_fsl_setup_phy(struct ehci_hcd *ehci,
 	ehci_writel(ehci, portsc, &ehci->regs->port_status[port_offset]);
 }
 
-static void ehci_fsl_usb_setup(struct ehci_hcd *ehci)
+static int ehci_fsl_usb_setup(struct ehci_hcd *ehci)
 {
 	struct usb_hcd *hcd = ehci_to_hcd(ehci);
 	struct fsl_usb2_platform_data *pdata;
@@ -299,12 +299,19 @@ static void ehci_fsl_usb_setup(struct ehci_hcd *ehci)
 #endif
 		out_be32(non_ehci + FSL_SOC_USB_SICTRL, 0x00000001);
 	}
+
+	if (!(in_be32(non_ehci + FSL_SOC_USB_CTRL) & CTRL_PHY_CLK_VALID)) {
+		printk(KERN_WARNING "fsl-ehci: USB PHY clock invalid\n");
+		return -ENODEV;
+	}
+	return 0;
 }
 
 /* called after powerup, by probe or system-pm "wakeup" */
 static int ehci_fsl_reinit(struct ehci_hcd *ehci)
 {
-	ehci_fsl_usb_setup(ehci);
+	if (ehci_fsl_usb_setup(ehci))
+		return -ENODEV;
 	ehci_port_power(ehci, 0);
 
 	return 0;

drivers/usb/host/ehci-fsl.h

@@ -45,5 +45,6 @@
 #define FSL_SOC_USB_PRICTRL	0x40c	/* NOTE: big-endian */
 #define FSL_SOC_USB_SICTRL	0x410	/* NOTE: big-endian */
 #define FSL_SOC_USB_CTRL	0x500	/* NOTE: big-endian */
+#define CTRL_PHY_CLK_VALID	(1 << 17)
 #define SNOOP_SIZE_2GB		0x1e
 #endif				/* _EHCI_FSL_H */