usb: cdns2: Fix controller reset issue

Patch fixes the procedure of resetting controller.
The CPUCTRL register is write only and reading returns 0.
Waiting for reset to complite is incorrect.

Fixes: 3eb1f1ef ("usb: cdns2: Add main part of Cadence USBHS driver")
cc: stable@vger.kernel.org
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/PH7PR07MB9538D56D75F1F399D0BB96F0DD922@PH7PR07MB9538.namprd07.prod.outlook.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/cdns2/cdns2-gadget.c

@@ -2251,7 +2251,6 @@ static int cdns2_gadget_start(struct cdns2_device *pdev)
 {
 	u32 max_speed;
 	void *buf;
-	int val;
 	int ret;
 
 	pdev->usb_regs = pdev->regs;
@@ -2261,14 +2260,9 @@ static int cdns2_gadget_start(struct cdns2_device *pdev)
 	pdev->adma_regs = pdev->regs + CDNS2_ADMA_REGS_OFFSET;
 
 	/* Reset controller. */
-	set_reg_bit_8(&pdev->usb_regs->cpuctrl, CPUCTRL_SW_RST);
-
-	ret = readl_poll_timeout_atomic(&pdev->usb_regs->cpuctrl, val,
-					!(val & CPUCTRL_SW_RST), 1, 10000);
-	if (ret) {
-		dev_err(pdev->dev, "Error: reset controller timeout\n");
-		return -EINVAL;
-	}
+	writeb(CPUCTRL_SW_RST | CPUCTRL_UPCLK | CPUCTRL_WUEN,
+	       &pdev->usb_regs->cpuctrl);
+	usleep_range(5, 10);
 
 	usb_initialize_gadget(pdev->dev, &pdev->gadget, NULL);
 

drivers/usb/gadget/udc/cdns2/cdns2-gadget.h

@@ -292,8 +292,17 @@ struct cdns2_usb_regs {
 #define SPEEDCTRL_HSDISABLE	BIT(7)
 
 /* CPUCTRL- bitmasks. */
+/* UP clock enable */
+#define CPUCTRL_UPCLK		BIT(0)
 /* Controller reset bit. */
 #define CPUCTRL_SW_RST		BIT(1)
+/**
+ * If the wuen bit is ‘1’, the upclken is automatically set to ‘1’ after
+ * detecting rising edge of wuintereq interrupt. If the wuen bit is ‘0’,
+ * the wuintereq interrupt is ignored.
+ */
+#define CPUCTRL_WUEN		BIT(7)
+
 
 /**
  * struct cdns2_adma_regs - ADMA controller registers.