phy: stm32: add phy tuning support

It can be necessary to adjust the phys settings to compensate parasitics.
This patch adds support of new optional properties to configure the tune
interface of the phys of stm32-usbphyc.
Properties are optional, that's why each property is skipped if not
found (-EINVAL).
Phy tuning is restored on resume because if deep low power state is
achieved, phy tuning configuration is reset.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20211015161427.220784-4-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 190 insertions, 0 deletions

diff --git a/drivers/phy/st/phy-stm32-usbphyc.c b/drivers/phy/st/phy-stm32-usbphyc.c
index 083593aea53a..7df6a63ad37b 100644
--- a/drivers/phy/st/phy-stm32-usbphyc.c
+++ b/drivers/phy/st/phy-stm32-usbphyc.c
@@ -20,6 +20,7 @@
 #define STM32_USBPHYC_PLL	0x0
 #define STM32_USBPHYC_MISC	0x8
 #define STM32_USBPHYC_MONITOR(X) (0x108 + ((X) * 0x100))
+#define STM32_USBPHYC_TUNE(X)	(0x10C + ((X) * 0x100))
 #define STM32_USBPHYC_VERSION	0x3F4
 
 /* STM32_USBPHYC_PLL bit fields */
@@ -41,6 +42,83 @@
 #define STM32_USBPHYC_MON_SEL_LOCKP 0x1F
 #define STM32_USBPHYC_MON_OUT_LOCKP BIT(3)
 
+/* STM32_USBPHYC_TUNE bit fields */
+#define INCURREN		BIT(0)
+#define INCURRINT		BIT(1)
+#define LFSCAPEN		BIT(2)
+#define HSDRVSLEW		BIT(3)
+#define HSDRVDCCUR		BIT(4)
+#define HSDRVDCLEV		BIT(5)
+#define HSDRVCURINCR		BIT(6)
+#define FSDRVRFADJ		BIT(7)
+#define HSDRVRFRED		BIT(8)
+#define HSDRVCHKITRM		GENMASK(12, 9)
+#define HSDRVCHKZTRM		GENMASK(14, 13)
+#define OTPCOMP			GENMASK(19, 15)
+#define SQLCHCTL		GENMASK(21, 20)
+#define HDRXGNEQEN		BIT(22)
+#define HSRXOFF			GENMASK(24, 23)
+#define HSFALLPREEM		BIT(25)
+#define SHTCCTCTLPROT		BIT(26)
+#define STAGSEL			BIT(27)
+
+enum boosting_vals {
+	BOOST_1000_UA = 1000,
+	BOOST_2000_UA = 2000,
+};
+
+enum dc_level_vals {
+	DC_NOMINAL,
+	DC_PLUS_5_TO_7_MV,
+	DC_PLUS_10_TO_14_MV,
+	DC_MINUS_5_TO_7_MV,
+	DC_MAX,
+};
+
+enum current_trim {
+	CUR_NOMINAL,
+	CUR_PLUS_1_56_PCT,
+	CUR_PLUS_3_12_PCT,
+	CUR_PLUS_4_68_PCT,
+	CUR_PLUS_6_24_PCT,
+	CUR_PLUS_7_8_PCT,
+	CUR_PLUS_9_36_PCT,
+	CUR_PLUS_10_92_PCT,
+	CUR_PLUS_12_48_PCT,
+	CUR_PLUS_14_04_PCT,
+	CUR_PLUS_15_6_PCT,
+	CUR_PLUS_17_16_PCT,
+	CUR_PLUS_19_01_PCT,
+	CUR_PLUS_20_58_PCT,
+	CUR_PLUS_22_16_PCT,
+	CUR_PLUS_23_73_PCT,
+	CUR_MAX,
+};
+
+enum impedance_trim {
+	IMP_NOMINAL,
+	IMP_MINUS_2_OHMS,
+	IMP_MINUS_4_OMHS,
+	IMP_MINUS_6_OHMS,
+	IMP_MAX,
+};
+
+enum squelch_level {
+	SQLCH_NOMINAL,
+	SQLCH_PLUS_7_MV,
+	SQLCH_MINUS_5_MV,
+	SQLCH_PLUS_14_MV,
+	SQLCH_MAX,
+};
+
+enum rx_offset {
+	NO_RX_OFFSET,
+	RX_OFFSET_PLUS_5_MV,
+	RX_OFFSET_PLUS_10_MV,
+	RX_OFFSET_MINUS_5_MV,
+	RX_OFFSET_MAX,
+};
+
 /* STM32_USBPHYC_VERSION bit fields */
 #define MINREV			GENMASK(3, 0)
 #define MAJREV			GENMASK(7, 4)
@@ -60,6 +138,7 @@ struct stm32_usbphyc_phy {
 	struct regulator *vbus;
 	u32 index;
 	bool active;
+	u32 tune;
 };
 
 struct stm32_usbphyc {
@@ -375,6 +454,107 @@ static int stm32_usbphyc_clk48_register(struct stm32_usbphyc *usbphyc)
 	return ret;
 }
 
+static void stm32_usbphyc_phy_tuning(struct stm32_usbphyc *usbphyc,
+				     struct device_node *np, u32 index)
+{
+	struct stm32_usbphyc_phy *usbphyc_phy = usbphyc->phys[index];
+	u32 reg = STM32_USBPHYC_TUNE(index);
+	u32 otpcomp, val;
+	int ret;
+
+	/* Backup OTP compensation code */
+	otpcomp = FIELD_GET(OTPCOMP, readl_relaxed(usbphyc->base + reg));
+
+	ret = of_property_read_u32(np, "st,current-boost-microamp", &val);
+	if (ret != -EINVAL) {
+		if (!ret && (val == BOOST_1000_UA || val == BOOST_2000_UA)) {
+			val = (val == BOOST_2000_UA) ? 1 : 0;
+			usbphyc_phy->tune |= INCURREN | FIELD_PREP(INCURRINT, val);
+		} else {
+			dev_warn(usbphyc->dev, "phy%d: invalid st,current-boost-microamp\n", index);
+		}
+	}
+
+	if (!of_property_read_bool(np, "st,no-lsfs-fb-cap"))
+		usbphyc_phy->tune |= LFSCAPEN;
+
+	if (of_property_read_bool(np, "st,slow-hs-slew-rate"))
+		usbphyc_phy->tune |= HSDRVSLEW;
+
+	ret = of_property_read_u32(np, "st,tune-hs-dc-level", &val);
+	if (ret != -EINVAL) {
+		if (!ret && val < DC_MAX) {
+			if (val == DC_MINUS_5_TO_7_MV) {/* Decreases HS driver DC level */
+				usbphyc_phy->tune |= HSDRVDCCUR;
+			} else if (val > 0) {		/* Increases HS driver DC level */
+				val = (val == DC_PLUS_10_TO_14_MV) ? 1 : 0;
+				usbphyc_phy->tune |= HSDRVCURINCR | FIELD_PREP(HSDRVDCLEV, val);
+			}
+		} else {
+			dev_warn(usbphyc->dev, "phy%d: invalid st,tune-hs-dc-level\n", index);
+		}
+	}
+
+	if (of_property_read_bool(np, "st,enable-fs-rftime-tuning"))
+		usbphyc_phy->tune |= FSDRVRFADJ;
+
+	if (of_property_read_bool(np, "st,enable-hs-rftime-reduction"))
+		usbphyc_phy->tune |= HSDRVRFRED;
+
+	ret = of_property_read_u32(np, "st,trim-hs-current", &val);
+	if (ret != -EINVAL) {
+		if (!ret && val < CUR_MAX)
+			usbphyc_phy->tune |= FIELD_PREP(HSDRVCHKITRM, val);
+		else
+			dev_warn(usbphyc->dev, "phy%d: invalid st,trim-hs-current\n", index);
+	}
+
+	ret = of_property_read_u32(np, "st,trim-hs-impedance", &val);
+	if (ret != -EINVAL) {
+		if (!ret && val < IMP_MAX)
+			usbphyc_phy->tune |= FIELD_PREP(HSDRVCHKZTRM, val);
+		else
+			dev_warn(usbphyc->dev, "phy%d: invalid st,trim-hs-impedance\n", index);
+	}
+
+	ret = of_property_read_u32(np, "st,tune-squelch-level", &val);
+	if (ret != -EINVAL) {
+		if (!ret && val < SQLCH_MAX)
+			usbphyc_phy->tune |= FIELD_PREP(SQLCHCTL, val);
+		else
+			dev_warn(usbphyc->dev, "phy%d: invalid st,tune-squelch\n", index);
+	}
+
+	if (of_property_read_bool(np, "st,enable-hs-rx-gain-eq"))
+		usbphyc_phy->tune |= HDRXGNEQEN;
+
+	ret = of_property_read_u32(np, "st,tune-hs-rx-offset", &val);
+	if (ret != -EINVAL) {
+		if (!ret && val < RX_OFFSET_MAX)
+			usbphyc_phy->tune |= FIELD_PREP(HSRXOFF, val);
+		else
+			dev_warn(usbphyc->dev, "phy%d: invalid st,tune-hs-rx-offset\n", index);
+	}
+
+	if (of_property_read_bool(np, "st,no-hs-ftime-ctrl"))
+		usbphyc_phy->tune |= HSFALLPREEM;
+
+	if (!of_property_read_bool(np, "st,no-lsfs-sc"))
+		usbphyc_phy->tune |= SHTCCTCTLPROT;
+
+	if (of_property_read_bool(np, "st,enable-hs-tx-staggering"))
+		usbphyc_phy->tune |= STAGSEL;
+
+	/* Restore OTP compensation code */
+	usbphyc_phy->tune |= FIELD_PREP(OTPCOMP, otpcomp);
+
+	/*
+	 * By default, if no st,xxx tuning property is used, usbphyc_phy->tune is equal to
+	 * STM32_USBPHYC_TUNE reset value (LFSCAPEN | SHTCCTCTLPROT | OTPCOMP).
+	 */
+	writel_relaxed(usbphyc_phy->tune, usbphyc->base + reg);
+}
+
 static void stm32_usbphyc_switch_setup(struct stm32_usbphyc *usbphyc,
 				       u32 utmi_switch)
 {
@@ -550,6 +730,9 @@ static int stm32_usbphyc_probe(struct platform_device *pdev)
 			usbphyc->phys[port]->vbus = NULL;
 		}
 
+		/* Configure phy tuning */
+		stm32_usbphyc_phy_tuning(usbphyc, child, index);
+
 		port++;
 	}
 
@@ -601,10 +784,17 @@ static int stm32_usbphyc_remove(struct platform_device *pdev)
 static int __maybe_unused stm32_usbphyc_resume(struct device *dev)
 {
 	struct stm32_usbphyc *usbphyc = dev_get_drvdata(dev);
+	struct stm32_usbphyc_phy *usbphyc_phy;
+	int port;
 
 	if (usbphyc->switch_setup >= 0)
 		stm32_usbphyc_switch_setup(usbphyc, usbphyc->switch_setup);
 
+	for (port = 0; port < usbphyc->nphys; port++) {
+		usbphyc_phy = usbphyc->phys[port];
+		writel_relaxed(usbphyc_phy->tune, usbphyc->base + STM32_USBPHYC_TUNE(port));
+	}
+
 	return 0;
 }