usb: dwc3: add dis_u2_freeclk_exists_quirk

Add a quirk to clear the GUSB2PHYCFG.U2_FREECLK_EXISTS bit,
which specifies whether the USB2.0 PHY provides a free-running
PHY clock, which is active when the clock control input is active.

Refer to commit 27f83eeb6b42("usb: dwc3: add dis_u2_freeclk_exists_quirk")
in Linux Rockchip Kernel.

Signed-off-by: Frank Wang <frank.wang@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 8b75de0..83a0782 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -403,6 +403,9 @@
 	if (dwc->dis_enblslpm_quirk)
 		reg &= ~DWC3_GUSB2PHYCFG_ENBLSLPM;
 
+	if (dwc->dis_u2_freeclk_exists_quirk)
+		reg &= ~DWC3_GUSB2PHYCFG_U2_FREECLK_EXISTS;
+
 	dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
 
 	mdelay(100);
@@ -725,6 +728,7 @@
 	dwc->dis_u2_susphy_quirk = dwc3_dev->dis_u2_susphy_quirk;
 	dwc->dis_del_phy_power_chg_quirk = dwc3_dev->dis_del_phy_power_chg_quirk;
 	dwc->dis_enblslpm_quirk = dwc3_dev->dis_enblslpm_quirk;
+	dwc->dis_u2_freeclk_exists_quirk = dwc3_dev->dis_u2_freeclk_exists_quirk;
 
 	dwc->tx_de_emphasis_quirk = dwc3_dev->tx_de_emphasis_quirk;
 	if (dwc3_dev->tx_de_emphasis)
@@ -934,6 +938,8 @@
 				"snps,dis-del-phy-power-chg-quirk");
 	dwc->dis_enblslpm_quirk = dev_read_bool(dev,
 				"snps,dis_enblslpm_quirk");
+	dwc->dis_u2_freeclk_exists_quirk = dev_read_bool(dev,
+				"snps,dis-u2-freeclk-exists-quirk");
 	dwc->tx_de_emphasis_quirk = dev_read_bool(dev,
 				"snps,tx_de_emphasis_quirk");
 	tmp = dev_read_u8_array_ptr(dev, "snps,tx_de_emphasis", 1);