phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY

Realtek DHC (digital home center) RTD SoCs support DWC3 XHCI USB
controller. Added the driver to drive the USB 2.0 PHY transceivers.

Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
Link: https://lore.kernel.org/r/20230725033318.8361-2-stanley_chang@realtek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/phy/Kconfig

@@ -87,6 +87,7 @@ source "drivers/phy/motorola/Kconfig"
 source "drivers/phy/mscc/Kconfig"
 source "drivers/phy/qualcomm/Kconfig"
 source "drivers/phy/ralink/Kconfig"
+source "drivers/phy/realtek/Kconfig"
 source "drivers/phy/renesas/Kconfig"
 source "drivers/phy/rockchip/Kconfig"
 source "drivers/phy/samsung/Kconfig"

drivers/phy/Makefile

@@ -26,6 +26,7 @@ obj-y					+= allwinner/	\
 					   mscc/	\
 					   qualcomm/	\
 					   ralink/	\
+					   realtek/	\
 					   renesas/	\
 					   rockchip/	\
 					   samsung/	\

drivers/phy/realtek/Kconfig

@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Phy drivers for Realtek platforms
+#
+config PHY_RTK_RTD_USB2PHY
+	tristate "Realtek RTD USB2 PHY Transceiver Driver"
+	depends on USB_SUPPORT
+	select GENERIC_PHY
+	select USB_PHY
+	help
+	  Enable this to support Realtek SoC USB2 phy transceiver.
+	  The DHC (digital home center) RTD series SoCs used the Synopsys
+	  DWC3 USB IP. This driver will do the PHY initialization
+	  of the parameters.

drivers/phy/realtek/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_PHY_RTK_RTD_USB2PHY)	+= phy-rtk-usb2.o