usb: otg: jz4780_platform: Switch off OTG PHY overcurrent warnings

Previously, the kernel log would be spammed with messages about an
overcurrent change being detected on the OTG port. Ingenic worked
around this in their 3.0.8 kernel by setting a bit in one of the
OTG controller's registers that would disable the warning. This
commit implements the same workaround, but for the 3.18 kernel.

drivers/usb/dwc2/jz4780_platform.c

@@ -49,7 +49,8 @@
 #include "core.h"
 #include "hcd.h"
 
-#define USBRESET_DETECT_TIME 0x96
+#define USBRESET_DETECT_TIME	0x96
+#define OTG_REG_GUSBCFG		0xb3500000
 
 static const char dwc2_driver_name[] = "dwc2-jz4780";
 
@@ -137,6 +138,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	struct resource *res;
 	int retval;
 	int irq;
+	u32 reg;
 	struct clk *clk_otg_phy, *clk_otg1;
 
 	if (usb_disabled())
@@ -281,6 +283,10 @@ static int dwc2_driver_probe(struct platform_device *dev)
 		goto err;
 	}
 
+	/* Switch off VBUS overcurrent detection in OTG PHY. */
+	reg = readl((unsigned int __iomem *)OTG_REG_GUSBCFG);
+	writel(reg | 0xc, (unsigned int __iomem *)OTG_REG_GUSBCFG);
+
 	retval = dwc2_hcd_init(hsotg, irq, params);
 	if (retval)
 		goto err;