phy: fsl-imx8mp-usb: add support for phy tuning

Add USB PHY parameter tuning for USB certifications.

Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Li Jun <jun.li@nxp.com>
[j.zink: ported to v6.3-rc1 from NXP downstream repo + cleanups]
Signed-off-by: Johannes Zink <j.zink@pengutronix.de>
Link: https://lore.kernel.org/r/20230516-lustige-usb-phy-dinge-v2-2-3383a0de34ac@pengutronix.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/phy/freescale/phy-fsl-imx8mq-usb.c

@@ -27,17 +27,231 @@
 #define PHY_CTRL2_TXENABLEN0		BIT(8)
 #define PHY_CTRL2_OTG_DISABLE		BIT(9)
 
+#define PHY_CTRL3			0xc
+#define PHY_CTRL3_COMPDISTUNE_MASK	GENMASK(2, 0)
+#define PHY_CTRL3_TXPREEMP_TUNE_MASK	GENMASK(16, 15)
+#define PHY_CTRL3_TXRISE_TUNE_MASK	GENMASK(21, 20)
+#define PHY_CTRL3_TXVREF_TUNE_MASK	GENMASK(25, 22)
+#define PHY_CTRL3_TX_VBOOST_LEVEL_MASK	GENMASK(31, 29)
+
+#define PHY_CTRL4			0x10
+#define PHY_CTRL4_PCS_TX_DEEMPH_3P5DB_MASK	GENMASK(20, 15)
+
+#define PHY_CTRL5			0x14
+#define PHY_CTRL5_DMPWD_OVERRIDE_SEL	BIT(23)
+#define PHY_CTRL5_DMPWD_OVERRIDE	BIT(22)
+#define PHY_CTRL5_DPPWD_OVERRIDE_SEL	BIT(21)
+#define PHY_CTRL5_DPPWD_OVERRIDE	BIT(20)
+#define PHY_CTRL5_PCS_TX_SWING_FULL_MASK	GENMASK(6, 0)
+
 #define PHY_CTRL6			0x18
 #define PHY_CTRL6_ALT_CLK_EN		BIT(1)
 #define PHY_CTRL6_ALT_CLK_SEL		BIT(0)
 
+#define PHY_TUNE_DEFAULT		0xffffffff
+
 struct imx8mq_usb_phy {
 	struct phy *phy;
 	struct clk *clk;
 	void __iomem *base;
 	struct regulator *vbus;
+	u32 pcs_tx_swing_full;
+	u32 pcs_tx_deemph_3p5db;
+	u32 tx_vref_tune;
+	u32 tx_rise_tune;
+	u32 tx_preemp_amp_tune;
+	u32 tx_vboost_level;
+	u32 comp_dis_tune;
 };
 
+static u32 phy_tx_vref_tune_from_property(u32 percent)
+{
+	percent = clamp(percent, 94U, 124U);
+
+	return DIV_ROUND_CLOSEST(percent - 94U, 2);
+}
+
+static u32 phy_tx_rise_tune_from_property(u32 percent)
+{
+	switch (percent) {
+	case 0 ... 98:
+		return 3;
+	case 99:
+		return 2;
+	case 100 ... 101:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+static u32 phy_tx_preemp_amp_tune_from_property(u32 microamp)
+{
+	microamp = min(microamp, 1800U);
+
+	return microamp / 600;
+}
+
+static u32 phy_tx_vboost_level_from_property(u32 microvolt)
+{
+	switch (microvolt) {
+	case 0 ... 960:
+		return 0;
+	case 961 ... 1160:
+		return 2;
+	default:
+		return 3;
+	}
+}
+
+static u32 phy_pcs_tx_deemph_3p5db_from_property(u32 decibel)
+{
+	return min(decibel, 36U);
+}
+
+static u32 phy_comp_dis_tune_from_property(u32 percent)
+{
+	switch (percent) {
+	case 0 ... 92:
+		return 0;
+	case 93 ... 95:
+		return 1;
+	case 96 ... 97:
+		return 2;
+	case 98 ... 102:
+		return 3;
+	case 103 ... 105:
+		return 4;
+	case 106 ... 109:
+		return 5;
+	case 110 ... 113:
+		return 6;
+	default:
+		return 7;
+	}
+}
+static u32 phy_pcs_tx_swing_full_from_property(u32 percent)
+{
+	percent = min(percent, 100U);
+
+	return (percent * 127) / 100;
+}
+
+static void imx8m_get_phy_tuning_data(struct imx8mq_usb_phy *imx_phy)
+{
+	struct device *dev = imx_phy->phy->dev.parent;
+
+	if (device_property_read_u32(dev, "fsl,phy-tx-vref-tune-percent",
+				     &imx_phy->tx_vref_tune))
+		imx_phy->tx_vref_tune = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->tx_vref_tune =
+			phy_tx_vref_tune_from_property(imx_phy->tx_vref_tune);
+
+	if (device_property_read_u32(dev, "fsl,phy-tx-rise-tune-percent",
+				     &imx_phy->tx_rise_tune))
+		imx_phy->tx_rise_tune = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->tx_rise_tune =
+			phy_tx_rise_tune_from_property(imx_phy->tx_rise_tune);
+
+	if (device_property_read_u32(dev, "fsl,phy-tx-preemp-amp-tune-microamp",
+				     &imx_phy->tx_preemp_amp_tune))
+		imx_phy->tx_preemp_amp_tune = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->tx_preemp_amp_tune =
+			phy_tx_preemp_amp_tune_from_property(imx_phy->tx_preemp_amp_tune);
+
+	if (device_property_read_u32(dev, "fsl,phy-tx-vboost-level-microvolt",
+				     &imx_phy->tx_vboost_level))
+		imx_phy->tx_vboost_level = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->tx_vboost_level =
+			phy_tx_vboost_level_from_property(imx_phy->tx_vboost_level);
+
+	if (device_property_read_u32(dev, "fsl,phy-comp-dis-tune-percent",
+				     &imx_phy->comp_dis_tune))
+		imx_phy->comp_dis_tune = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->comp_dis_tune =
+			phy_comp_dis_tune_from_property(imx_phy->comp_dis_tune);
+
+	if (device_property_read_u32(dev, "fsl,pcs-tx-deemph-3p5db-attenuation-db",
+				     &imx_phy->pcs_tx_deemph_3p5db))
+		imx_phy->pcs_tx_deemph_3p5db = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->pcs_tx_deemph_3p5db =
+			phy_pcs_tx_deemph_3p5db_from_property(imx_phy->pcs_tx_deemph_3p5db);
+
+	if (device_property_read_u32(dev, "fsl,phy-pcs-tx-swing-full-percent",
+				     &imx_phy->pcs_tx_swing_full))
+		imx_phy->pcs_tx_swing_full = PHY_TUNE_DEFAULT;
+	else
+		imx_phy->pcs_tx_swing_full =
+			phy_pcs_tx_swing_full_from_property(imx_phy->pcs_tx_swing_full);
+}
+
+static void imx8m_phy_tune(struct imx8mq_usb_phy *imx_phy)
+{
+	u32 value;
+
+	/* PHY tuning */
+	if (imx_phy->pcs_tx_deemph_3p5db != PHY_TUNE_DEFAULT) {
+		value = readl(imx_phy->base + PHY_CTRL4);
+		value &= ~PHY_CTRL4_PCS_TX_DEEMPH_3P5DB_MASK;
+		value |= FIELD_PREP(PHY_CTRL4_PCS_TX_DEEMPH_3P5DB_MASK,
+				   imx_phy->pcs_tx_deemph_3p5db);
+		writel(value, imx_phy->base + PHY_CTRL4);
+	}
+
+	if (imx_phy->pcs_tx_swing_full != PHY_TUNE_DEFAULT) {
+		value = readl(imx_phy->base + PHY_CTRL5);
+		value |= FIELD_PREP(PHY_CTRL5_PCS_TX_SWING_FULL_MASK,
+				   imx_phy->pcs_tx_swing_full);
+		writel(value, imx_phy->base + PHY_CTRL5);
+	}
+
+	if ((imx_phy->tx_vref_tune & imx_phy->tx_rise_tune &
+	     imx_phy->tx_preemp_amp_tune & imx_phy->comp_dis_tune &
+	     imx_phy->tx_vboost_level) == PHY_TUNE_DEFAULT)
+		/* If all are the default values, no need update. */
+		return;
+
+	value = readl(imx_phy->base + PHY_CTRL3);
+
+	if (imx_phy->tx_vref_tune != PHY_TUNE_DEFAULT) {
+		value &= ~PHY_CTRL3_TXVREF_TUNE_MASK;
+		value |= FIELD_PREP(PHY_CTRL3_TXVREF_TUNE_MASK,
+				   imx_phy->tx_vref_tune);
+	}
+
+	if (imx_phy->tx_rise_tune != PHY_TUNE_DEFAULT) {
+		value &= ~PHY_CTRL3_TXRISE_TUNE_MASK;
+		value |= FIELD_PREP(PHY_CTRL3_TXRISE_TUNE_MASK,
+				    imx_phy->tx_rise_tune);
+	}
+
+	if (imx_phy->tx_preemp_amp_tune != PHY_TUNE_DEFAULT) {
+		value &= ~PHY_CTRL3_TXPREEMP_TUNE_MASK;
+		value |= FIELD_PREP(PHY_CTRL3_TXPREEMP_TUNE_MASK,
+				imx_phy->tx_preemp_amp_tune);
+	}
+
+	if (imx_phy->comp_dis_tune != PHY_TUNE_DEFAULT) {
+		value &= ~PHY_CTRL3_COMPDISTUNE_MASK;
+		value |= FIELD_PREP(PHY_CTRL3_COMPDISTUNE_MASK,
+				    imx_phy->comp_dis_tune);
+	}
+
+	if (imx_phy->tx_vboost_level != PHY_TUNE_DEFAULT) {
+		value &= ~PHY_CTRL3_TX_VBOOST_LEVEL_MASK;
+		value |= FIELD_PREP(PHY_CTRL3_TX_VBOOST_LEVEL_MASK,
+				    imx_phy->tx_vboost_level);
+	}
+
+	writel(value, imx_phy->base + PHY_CTRL3);
+}
+
 static int imx8mq_usb_phy_init(struct phy *phy)
 {
 	struct imx8mq_usb_phy *imx_phy = phy_get_drvdata(phy);
@@ -99,6 +313,8 @@ static int imx8mp_usb_phy_init(struct phy *phy)
 	value &= ~(PHY_CTRL1_RESET | PHY_CTRL1_ATERESET);
 	writel(value, imx_phy->base + PHY_CTRL1);
 
+	imx8m_phy_tune(imx_phy);
+
 	return 0;
 }
 
@@ -182,6 +398,8 @@ static int imx8mq_usb_phy_probe(struct platform_device *pdev)
 
 	phy_set_drvdata(imx_phy->phy, imx_phy);
 
+	imx8m_get_phy_tuning_data(imx_phy);
+
 	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
 
 	return PTR_ERR_OR_ZERO(phy_provider);