usb: dwc2: Add support for STM32F429/439/469 USB OTG HS/FS in FS mode (internal PHY)

This patch introduces a new parameter to activate USB OTG HS/FS core
embedded phy transceiver. The STM32F4x9 SoC uses the GGPIO register
to enable the transceiver.
Also add the dwc2_set_params function for stm32f4 otg fs.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Bruno Herrera <bruherrera@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 91ed5b6..740c7e8 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -121,7 +121,7 @@ static void dwc2_init_fs_ls_pclk_sel(struct dwc2_hsotg *hsotg)
 
 static int dwc2_fs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
 {
-	u32 usbcfg, i2cctl;
+	u32 usbcfg, ggpio, i2cctl;
 	int retval = 0;
 
 	/*
@@ -145,6 +145,19 @@ static int dwc2_fs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
 				return retval;
 			}
 		}
+
+		if (hsotg->params.activate_stm_fs_transceiver) {
+			ggpio = dwc2_readl(hsotg->regs + GGPIO);
+			if (!(ggpio & GGPIO_STM32_OTG_GCCFG_PWRDWN)) {
+				dev_dbg(hsotg->dev, "Activating transceiver\n");
+				/*
+				 * STM32F4x9 uses the GGPIO register as general
+				 * core configuration register.
+				 */
+				ggpio |= GGPIO_STM32_OTG_GCCFG_PWRDWN;
+				dwc2_writel(ggpio, hsotg->regs + GGPIO);
+			}
+		}
 	}
 
 	/*