MLK-16576 usb: phy: mxs: set hold_ring_off for USB2 PLL power up

USB2 PLL use ring VCO, when the PLL power up, the ring VCO’s supply also
ramp up. There is a possibility that the ring VCO start oscillation at
multi nodes in this phase, especially for VCO which has many stages, then
the multiwave will kept until PLL power down. Hold_ring_off(bit11) can
force the VCO in one determined state when VCO supply start ramp up, to
avoid this multiwave issue. Per IC design's suggestion it's better this
bit can be off from 25us after pll power up to 25us before USB TX/RX.

Acked-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
(cherry picked from commit a094377f04c9ed2c8e702ee7bfab843caa03eb96)

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-mxs-usb.c b/drivers/usb/phy/phy-mxs-usb.c
index d3b1187d67fd..73cb7c42e69f 100644
--- a/drivers/usb/phy/phy-mxs-usb.c
+++ b/drivers/usb/phy/phy-mxs-usb.c
@@ -72,6 +72,9 @@
 #define BM_USBPHY_PLL_EN_USB_CLKS		BIT(6)
 
 /* Anatop Registers */
+#define ANADIG_PLL_USB2				0x20
+#define ANADIG_PLL_USB2_SET			0x24
+#define ANADIG_PLL_USB2_CLR			0x28
 #define ANADIG_REG_1P1_SET			0x114
 #define ANADIG_REG_1P1_CLR			0x118
 
@@ -130,6 +133,8 @@
 #define BM_ANADIG_REG_1P1_ENABLE_WEAK_LINREG	BIT(18)
 #define BM_ANADIG_REG_1P1_TRACK_VDD_SOC_CAP	BIT(19)
 
+#define BM_ANADIG_PLL_USB2_HOLD_RING_OFF	BIT(11)
+
 #define to_mxs_phy(p) container_of((p), struct mxs_phy, phy)
 
 /* Do disconnection between PHY and controller without vbus */
@@ -545,6 +550,22 @@ static int mxs_phy_suspend(struct usb_phy *x, int suspend)
 		} else {
 			writel(0xffffffff, x->io_priv + HW_USBPHY_PWD);
 		}
+
+		/*
+		 * USB2 PLL use ring VCO, when the PLL power up, the ring
+		 * VCO’s supply also ramp up. There is a possibility that
+		 * the ring VCO start oscillation at multi nodes in this
+		 * phase, especially for VCO which has many stages, then
+		 * the multiwave will be kept until PLL power down. the bit
+		 * hold_ring_off can force the VCO in one determined state
+		 * to avoid the multiwave issue when VCO supply start ramp
+		 * up.
+		 */
+		if (mxs_phy->port_id == 1 && mxs_phy->regmap_anatop)
+			regmap_write(mxs_phy->regmap_anatop,
+				     ANADIG_PLL_USB2_SET,
+				     BM_ANADIG_PLL_USB2_HOLD_RING_OFF);
+
 		writel(BM_USBPHY_CTRL_CLKGATE,
 		       x->io_priv + HW_USBPHY_CTRL_SET);
 		if (!(mxs_phy->port_id == 1 &&
@@ -558,6 +579,20 @@ static int mxs_phy_suspend(struct usb_phy *x, int suspend)
 			if (ret)
 				return ret;
 		}
+
+		/*
+		 * Per IC design's requirement, hold_ring_off bit can be
+		 * cleared 25us after PLL power up and 25us before any USB
+		 * TX/RX.
+		 */
+		if (mxs_phy->port_id == 1 && mxs_phy->regmap_anatop) {
+			udelay(25);
+			regmap_write(mxs_phy->regmap_anatop,
+				     ANADIG_PLL_USB2_CLR,
+				     BM_ANADIG_PLL_USB2_HOLD_RING_OFF);
+			udelay(25);
+		}
+
 		writel(BM_USBPHY_CTRL_CLKGATE,
 		       x->io_priv + HW_USBPHY_CTRL_CLR);
 		writel(0, x->io_priv + HW_USBPHY_PWD);