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From:   Amelie Delaunay <amelie.delaunay@foss.st.com>
To:     Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>
CC:     <linux-phy@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        Amelie Delaunay <amelie.delaunay@foss.st.com>
Subject: [PATCH v3 3/3] phy: stm32: add phy tuning support
Date:   Fri, 15 Oct 2021 18:14:27 +0200
Message-ID: <20211015161427.220784-4-amelie.delaunay@foss.st.com>
In-Reply-To: <20211015161427.220784-1-amelie.delaunay@foss.st.com>
References: <20211015161427.220784-1-amelie.delaunay@foss.st.com>
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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>
---
 drivers/phy/st/phy-stm32-usbphyc.c | 190 +++++++++++++++++++++++++++++
 1 file changed, 190 insertions(+)

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;
 }
 
-- 
2.25.1