net: stmmac: dwmac-sogfpga: use the lynx pcs driver

dwmac_socfpga re-implements support for the TSE PCS, which is identical
to the already existing TSE PCS, which in turn is the same as the Lynx
PCS. Drop the existing TSE re-implemenation and use the Lynx PCS
instead, relying on the regmap-mdio driver to translate MDIO accesses
into mmio accesses.

Add a lynx_pcs reference in the stmmac's internal structure, and use
.mac_select_pcs() to return the relevant PCS to be used.
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/Kconfig

@@ -158,6 +158,9 @@ config DWMAC_SOCFPGA
 	default ARCH_INTEL_SOCFPGA
 	depends on OF && (ARCH_INTEL_SOCFPGA || COMPILE_TEST)
 	select MFD_SYSCON
+	select MDIO_REGMAP
+	select REGMAP_MMIO
+	select PCS_LYNX
 	help
 	  Support for ethernet controller on Altera SOCFPGA
 

drivers/net/ethernet/stmicro/stmmac/Makefile

@@ -35,7 +35,7 @@ obj-$(CONFIG_DWMAC_IMX8)	+= dwmac-imx.o
 obj-$(CONFIG_DWMAC_TEGRA)	+= dwmac-tegra.o
 obj-$(CONFIG_DWMAC_VISCONTI)	+= dwmac-visconti.o
 stmmac-platform-objs:= stmmac_platform.o
-dwmac-altr-socfpga-objs := altr_tse_pcs.o dwmac-socfpga.o
+dwmac-altr-socfpga-objs := dwmac-socfpga.o
 
 obj-$(CONFIG_STMMAC_PCI)	+= stmmac-pci.o
 obj-$(CONFIG_DWMAC_INTEL)	+= dwmac-intel.o

drivers/net/ethernet/stmicro/stmmac/altr_tse_pcs.c

-// SPDX-License-Identifier: GPL-2.0-only
-/* Copyright Altera Corporation (C) 2016. All rights reserved.
- *
- * Author: Tien Hock Loh <thloh@altera.com>
- */
-
-#include <linux/mfd/syscon.h>
-#include <linux/of.h>
-#include <linux/of_address.h>
-#include <linux/of_net.h>
-#include <linux/phy.h>
-#include <linux/regmap.h>
-#include <linux/reset.h>
-#include <linux/stmmac.h>
-
-#include "stmmac.h"
-#include "stmmac_platform.h"
-#include "altr_tse_pcs.h"
-
-#define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_GMII_MII	0
-#define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RGMII		BIT(1)
-#define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RMII		BIT(2)
-#define SYSMGR_EMACGRP_CTRL_PHYSEL_WIDTH		2
-#define SYSMGR_EMACGRP_CTRL_PHYSEL_MASK			GENMASK(1, 0)
-
-#define TSE_PCS_CONTROL_AN_EN_MASK			BIT(12)
-#define TSE_PCS_CONTROL_REG				0x00
-#define TSE_PCS_CONTROL_RESTART_AN_MASK			BIT(9)
-#define TSE_PCS_CTRL_AUTONEG_SGMII			0x1140
-#define TSE_PCS_IF_MODE_REG				0x28
-#define TSE_PCS_LINK_TIMER_0_REG			0x24
-#define TSE_PCS_LINK_TIMER_1_REG			0x26
-#define TSE_PCS_SIZE					0x40
-#define TSE_PCS_STATUS_AN_COMPLETED_MASK		BIT(5)
-#define TSE_PCS_STATUS_LINK_MASK			0x0004
-#define TSE_PCS_STATUS_REG				0x02
-#define TSE_PCS_SGMII_SPEED_1000			BIT(3)
-#define TSE_PCS_SGMII_SPEED_100				BIT(2)
-#define TSE_PCS_SGMII_SPEED_10				0x0
-#define TSE_PCS_SW_RST_MASK				0x8000
-#define TSE_PCS_PARTNER_ABILITY_REG			0x0A
-#define TSE_PCS_PARTNER_DUPLEX_FULL			0x1000
-#define TSE_PCS_PARTNER_DUPLEX_HALF			0x0000
-#define TSE_PCS_PARTNER_DUPLEX_MASK			0x1000
-#define TSE_PCS_PARTNER_SPEED_MASK			GENMASK(11, 10)
-#define TSE_PCS_PARTNER_SPEED_1000			BIT(11)
-#define TSE_PCS_PARTNER_SPEED_100			BIT(10)
-#define TSE_PCS_PARTNER_SPEED_10			0x0000
-#define TSE_PCS_PARTNER_SPEED_1000			BIT(11)
-#define TSE_PCS_PARTNER_SPEED_100			BIT(10)
-#define TSE_PCS_PARTNER_SPEED_10			0x0000
-#define TSE_PCS_SGMII_SPEED_MASK			GENMASK(3, 2)
-#define TSE_PCS_SGMII_LINK_TIMER_0			0x0D40
-#define TSE_PCS_SGMII_LINK_TIMER_1			0x0003
-#define TSE_PCS_SW_RESET_TIMEOUT			100
-#define TSE_PCS_USE_SGMII_AN_MASK			BIT(1)
-#define TSE_PCS_USE_SGMII_ENA				BIT(0)
-#define TSE_PCS_IF_USE_SGMII				0x03
-
-#define AUTONEGO_LINK_TIMER				20
-
-static int tse_pcs_reset(void __iomem *base, struct tse_pcs *pcs)
-{
-	int counter = 0;
-	u16 val;
-
-	val = readw(base + TSE_PCS_CONTROL_REG);
-	val |= TSE_PCS_SW_RST_MASK;
-	writew(val, base + TSE_PCS_CONTROL_REG);
-
-	while (counter < TSE_PCS_SW_RESET_TIMEOUT) {
-		val = readw(base + TSE_PCS_CONTROL_REG);
-		val &= TSE_PCS_SW_RST_MASK;
-		if (val == 0)
-			break;
-		counter++;
-		udelay(1);
-	}
-	if (counter >= TSE_PCS_SW_RESET_TIMEOUT) {
-		dev_err(pcs->dev, "PCS could not get out of sw reset\n");
-		return -ETIMEDOUT;
-	}
-
-	return 0;
-}
-
-int tse_pcs_init(void __iomem *base, struct tse_pcs *pcs)
-{
-	int ret = 0;
-
-	writew(TSE_PCS_IF_USE_SGMII, base + TSE_PCS_IF_MODE_REG);
-
-	writew(TSE_PCS_CTRL_AUTONEG_SGMII, base + TSE_PCS_CONTROL_REG);
-
-	writew(TSE_PCS_SGMII_LINK_TIMER_0, base + TSE_PCS_LINK_TIMER_0_REG);
-	writew(TSE_PCS_SGMII_LINK_TIMER_1, base + TSE_PCS_LINK_TIMER_1_REG);
-
-	ret = tse_pcs_reset(base, pcs);
-	if (ret == 0)
-		writew(SGMII_ADAPTER_ENABLE,
-		       pcs->sgmii_adapter_base + SGMII_ADAPTER_CTRL_REG);
-
-	return ret;
-}
-
-static void pcs_link_timer_callback(struct tse_pcs *pcs)
-{
-	u16 val = 0;
-	void __iomem *tse_pcs_base = pcs->tse_pcs_base;
-	void __iomem *sgmii_adapter_base = pcs->sgmii_adapter_base;
-
-	val = readw(tse_pcs_base + TSE_PCS_STATUS_REG);
-	val &= TSE_PCS_STATUS_LINK_MASK;
-
-	if (val != 0) {
-		dev_dbg(pcs->dev, "Adapter: Link is established\n");
-		writew(SGMII_ADAPTER_ENABLE,
-		       sgmii_adapter_base + SGMII_ADAPTER_CTRL_REG);
-	} else {
-		mod_timer(&pcs->aneg_link_timer, jiffies +
-			  msecs_to_jiffies(AUTONEGO_LINK_TIMER));
-	}
-}
-
-static void auto_nego_timer_callback(struct tse_pcs *pcs)
-{
-	u16 val = 0;
-	u16 speed = 0;
-	u16 duplex = 0;
-	void __iomem *tse_pcs_base = pcs->tse_pcs_base;
-	void __iomem *sgmii_adapter_base = pcs->sgmii_adapter_base;
-
-	val = readw(tse_pcs_base + TSE_PCS_STATUS_REG);
-	val &= TSE_PCS_STATUS_AN_COMPLETED_MASK;
-
-	if (val != 0) {
-		dev_dbg(pcs->dev, "Adapter: Auto Negotiation is completed\n");
-		val = readw(tse_pcs_base + TSE_PCS_PARTNER_ABILITY_REG);
-		speed = val & TSE_PCS_PARTNER_SPEED_MASK;
-		duplex = val & TSE_PCS_PARTNER_DUPLEX_MASK;
-
-		if (speed == TSE_PCS_PARTNER_SPEED_10 &&
-		    duplex == TSE_PCS_PARTNER_DUPLEX_FULL)
-			dev_dbg(pcs->dev,
-				"Adapter: Link Partner is Up - 10/Full\n");
-		else if (speed == TSE_PCS_PARTNER_SPEED_100 &&
-			 duplex == TSE_PCS_PARTNER_DUPLEX_FULL)
-			dev_dbg(pcs->dev,
-				"Adapter: Link Partner is Up - 100/Full\n");
-		else if (speed == TSE_PCS_PARTNER_SPEED_1000 &&
-			 duplex == TSE_PCS_PARTNER_DUPLEX_FULL)
-			dev_dbg(pcs->dev,
-				"Adapter: Link Partner is Up - 1000/Full\n");
-		else if (speed == TSE_PCS_PARTNER_SPEED_10 &&
-			 duplex == TSE_PCS_PARTNER_DUPLEX_HALF)
-			dev_err(pcs->dev,
-				"Adapter does not support Half Duplex\n");
-		else if (speed == TSE_PCS_PARTNER_SPEED_100 &&
-			 duplex == TSE_PCS_PARTNER_DUPLEX_HALF)
-			dev_err(pcs->dev,
-				"Adapter does not support Half Duplex\n");
-		else if (speed == TSE_PCS_PARTNER_SPEED_1000 &&
-			 duplex == TSE_PCS_PARTNER_DUPLEX_HALF)
-			dev_err(pcs->dev,
-				"Adapter does not support Half Duplex\n");
-		else
-			dev_err(pcs->dev,
-				"Adapter: Invalid Partner Speed and Duplex\n");
-
-		if (duplex == TSE_PCS_PARTNER_DUPLEX_FULL &&
-		    (speed == TSE_PCS_PARTNER_SPEED_10 ||
-		     speed == TSE_PCS_PARTNER_SPEED_100 ||
-		     speed == TSE_PCS_PARTNER_SPEED_1000))
-			writew(SGMII_ADAPTER_ENABLE,
-			       sgmii_adapter_base + SGMII_ADAPTER_CTRL_REG);
-	} else {
-		val = readw(tse_pcs_base + TSE_PCS_CONTROL_REG);
-		val |= TSE_PCS_CONTROL_RESTART_AN_MASK;
-		writew(val, tse_pcs_base + TSE_PCS_CONTROL_REG);
-
-		tse_pcs_reset(tse_pcs_base, pcs);
-		mod_timer(&pcs->aneg_link_timer, jiffies +
-			  msecs_to_jiffies(AUTONEGO_LINK_TIMER));
-	}
-}
-
-static void aneg_link_timer_callback(struct timer_list *t)
-{
-	struct tse_pcs *pcs = from_timer(pcs, t, aneg_link_timer);
-
-	if (pcs->autoneg == AUTONEG_ENABLE)
-		auto_nego_timer_callback(pcs);
-	else if (pcs->autoneg == AUTONEG_DISABLE)
-		pcs_link_timer_callback(pcs);
-}
-
-void tse_pcs_fix_mac_speed(struct tse_pcs *pcs, struct phy_device *phy_dev,
-			   unsigned int speed)
-{
-	void __iomem *tse_pcs_base = pcs->tse_pcs_base;
-	u32 val;
-
-	pcs->autoneg = phy_dev->autoneg;
-
-	if (phy_dev->autoneg == AUTONEG_ENABLE) {
-		val = readw(tse_pcs_base + TSE_PCS_CONTROL_REG);
-		val |= TSE_PCS_CONTROL_AN_EN_MASK;
-		writew(val, tse_pcs_base + TSE_PCS_CONTROL_REG);
-
-		val = readw(tse_pcs_base + TSE_PCS_IF_MODE_REG);
-		val |= TSE_PCS_USE_SGMII_AN_MASK;
-		writew(val, tse_pcs_base + TSE_PCS_IF_MODE_REG);
-
-		val = readw(tse_pcs_base + TSE_PCS_CONTROL_REG);
-		val |= TSE_PCS_CONTROL_RESTART_AN_MASK;
-
-		tse_pcs_reset(tse_pcs_base, pcs);
-
-		timer_setup(&pcs->aneg_link_timer, aneg_link_timer_callback,
-			    0);
-		mod_timer(&pcs->aneg_link_timer, jiffies +
-			  msecs_to_jiffies(AUTONEGO_LINK_TIMER));
-	} else if (phy_dev->autoneg == AUTONEG_DISABLE) {
-		val = readw(tse_pcs_base + TSE_PCS_CONTROL_REG);
-		val &= ~TSE_PCS_CONTROL_AN_EN_MASK;
-		writew(val, tse_pcs_base + TSE_PCS_CONTROL_REG);
-
-		val = readw(tse_pcs_base + TSE_PCS_IF_MODE_REG);
-		val &= ~TSE_PCS_USE_SGMII_AN_MASK;
-		writew(val, tse_pcs_base + TSE_PCS_IF_MODE_REG);
-
-		val = readw(tse_pcs_base + TSE_PCS_IF_MODE_REG);
-		val &= ~TSE_PCS_SGMII_SPEED_MASK;
-
-		switch (speed) {
-		case 1000:
-			val |= TSE_PCS_SGMII_SPEED_1000;
-			break;
-		case 100:
-			val |= TSE_PCS_SGMII_SPEED_100;
-			break;
-		case 10:
-			val |= TSE_PCS_SGMII_SPEED_10;
-			break;
-		default:
-			return;
-		}
-		writew(val, tse_pcs_base + TSE_PCS_IF_MODE_REG);
-
-		tse_pcs_reset(tse_pcs_base, pcs);
-
-		timer_setup(&pcs->aneg_link_timer, aneg_link_timer_callback,
-			    0);
-		mod_timer(&pcs->aneg_link_timer, jiffies +
-			  msecs_to_jiffies(AUTONEGO_LINK_TIMER));
-	}
-}

drivers/net/ethernet/stmicro/stmmac/altr_tse_pcs.h

-/* SPDX-License-Identifier: GPL-2.0-only */
-/* Copyright Altera Corporation (C) 2016. All rights reserved.
- *
- * Author: Tien Hock Loh <thloh@altera.com>
- */
-
-#ifndef __TSE_PCS_H__
-#define __TSE_PCS_H__
-
-#include <linux/phy.h>
-#include <linux/timer.h>
-
-#define SGMII_ADAPTER_CTRL_REG		0x00
-#define SGMII_ADAPTER_ENABLE		0x0000
-#define SGMII_ADAPTER_DISABLE		0x0001
-
-struct tse_pcs {
-	struct device *dev;
-	void __iomem *tse_pcs_base;
-	void __iomem *sgmii_adapter_base;
-	struct timer_list aneg_link_timer;
-	int autoneg;
-};
-
-int tse_pcs_init(void __iomem *base, struct tse_pcs *pcs);
-void tse_pcs_fix_mac_speed(struct tse_pcs *pcs, struct phy_device *phy_dev,
-			   unsigned int speed);
-
-#endif /* __TSE_PCS_H__ */

drivers/net/ethernet/stmicro/stmmac/common.h

@@ -16,6 +16,7 @@
 #include <linux/stmmac.h>
 #include <linux/phy.h>
 #include <linux/pcs/pcs-xpcs.h>
+#include <linux/pcs-lynx.h>
 #include <linux/module.h>
 #if IS_ENABLED(CONFIG_VLAN_8021Q)
 #define STMMAC_VLAN_TAG_USED
@@ -519,6 +520,7 @@ struct mac_device_info {
 	const struct stmmac_tc_ops *tc;
 	const struct stmmac_mmc_ops *mmc;
 	struct dw_xpcs *xpcs;
+	struct phylink_pcs *lynx_pcs; /* Lynx external PCS */
 	struct mii_regs mii;	/* MII register Addresses */
 	struct mac_link link;
 	void __iomem *pcsr;     /* vpointer to device CSRs */

drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c

@@ -10,14 +10,13 @@
 #include <linux/of_net.h>
 #include <linux/phy.h>
 #include <linux/regmap.h>
+#include <linux/mdio/mdio-regmap.h>
 #include <linux/reset.h>
 #include <linux/stmmac.h>
 
 #include "stmmac.h"
 #include "stmmac_platform.h"
 
-#include "altr_tse_pcs.h"
-
 #define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_GMII_MII 0x0
 #define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RGMII 0x1
 #define SYSMGR_EMACGRP_CTRL_PHYSEL_ENUM_RMII 0x2
@@ -37,6 +36,10 @@
 #define EMAC_SPLITTER_CTRL_SPEED_100		0x3
 #define EMAC_SPLITTER_CTRL_SPEED_1000		0x0
 
+#define SGMII_ADAPTER_CTRL_REG		0x00
+#define SGMII_ADAPTER_ENABLE		0x0000
+#define SGMII_ADAPTER_DISABLE		0x0001
+
 struct socfpga_dwmac;
 struct socfpga_dwmac_ops {
 	int (*set_phy_mode)(struct socfpga_dwmac *dwmac_priv);
@@ -50,16 +53,18 @@ struct socfpga_dwmac {
 	struct reset_control *stmmac_rst;
 	struct reset_control *stmmac_ocp_rst;
 	void __iomem *splitter_base;
+	void __iomem *tse_pcs_base;
+	void __iomem *sgmii_adapter_base;
 	bool f2h_ptp_ref_clk;
-	struct tse_pcs pcs;
 	const struct socfpga_dwmac_ops *ops;
+	struct mdio_device *pcs_mdiodev;
 };
 
 static void socfpga_dwmac_fix_mac_speed(void *priv, unsigned int speed)
 {
 	struct socfpga_dwmac *dwmac = (struct socfpga_dwmac *)priv;
 	void __iomem *splitter_base = dwmac->splitter_base;
-	void __iomem *sgmii_adapter_base = dwmac->pcs.sgmii_adapter_base;
+	void __iomem *sgmii_adapter_base = dwmac->sgmii_adapter_base;
 	struct device *dev = dwmac->dev;
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct phy_device *phy_dev = ndev->phydev;
@@ -89,11 +94,9 @@ static void socfpga_dwmac_fix_mac_speed(void *priv, unsigned int speed)
 		writel(val, splitter_base + EMAC_SPLITTER_CTRL_REG);
 	}
 
-	if (phy_dev && sgmii_adapter_base) {
+	if (phy_dev && sgmii_adapter_base)
 		writew(SGMII_ADAPTER_ENABLE,
 		       sgmii_adapter_base + SGMII_ADAPTER_CTRL_REG);
-		tse_pcs_fix_mac_speed(&dwmac->pcs, phy_dev, speed);
-	}
 }
 
 static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *dev)
@@ -183,11 +186,11 @@ static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *
 				goto err_node_put;
 			}
 
-			dwmac->pcs.sgmii_adapter_base =
+			dwmac->sgmii_adapter_base =
 			    devm_ioremap_resource(dev, &res_sgmii_adapter);
 
-			if (IS_ERR(dwmac->pcs.sgmii_adapter_base)) {
-				ret = PTR_ERR(dwmac->pcs.sgmii_adapter_base);
+			if (IS_ERR(dwmac->sgmii_adapter_base)) {
+				ret = PTR_ERR(dwmac->sgmii_adapter_base);
 				goto err_node_put;
 			}
 		}
@@ -205,11 +208,11 @@ static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *
 				goto err_node_put;
 			}
 
-			dwmac->pcs.tse_pcs_base =
+			dwmac->tse_pcs_base =
 			    devm_ioremap_resource(dev, &res_tse_pcs);
 
-			if (IS_ERR(dwmac->pcs.tse_pcs_base)) {
-				ret = PTR_ERR(dwmac->pcs.tse_pcs_base);
+			if (IS_ERR(dwmac->tse_pcs_base)) {
+				ret = PTR_ERR(dwmac->tse_pcs_base);
 				goto err_node_put;
 			}
 		}
@@ -235,6 +238,13 @@ static int socfpga_get_plat_phymode(struct socfpga_dwmac *dwmac)
 	return priv->plat->interface;
 }
 
+static void socfpga_sgmii_config(struct socfpga_dwmac *dwmac, bool enable)
+{
+	u16 val = enable ? SGMII_ADAPTER_ENABLE : SGMII_ADAPTER_DISABLE;
+
+	writew(val, dwmac->sgmii_adapter_base + SGMII_ADAPTER_CTRL_REG);
+}
+
 static int socfpga_set_phy_mode_common(int phymode, u32 *val)
 {
 	switch (phymode) {
@@ -310,12 +320,8 @@ static int socfpga_gen5_set_phy_mode(struct socfpga_dwmac *dwmac)
 	 */
 	reset_control_deassert(dwmac->stmmac_ocp_rst);
 	reset_control_deassert(dwmac->stmmac_rst);
-	if (phymode == PHY_INTERFACE_MODE_SGMII) {
-		if (tse_pcs_init(dwmac->pcs.tse_pcs_base, &dwmac->pcs) != 0) {
-			dev_err(dwmac->dev, "Unable to initialize TSE PCS");
-			return -EINVAL;
-		}
-	}
+	if (phymode == PHY_INTERFACE_MODE_SGMII)
+		socfpga_sgmii_config(dwmac, true);
 
 	return 0;
 }
@@ -367,12 +373,8 @@ static int socfpga_gen10_set_phy_mode(struct socfpga_dwmac *dwmac)
 	 */
 	reset_control_deassert(dwmac->stmmac_ocp_rst);
 	reset_control_deassert(dwmac->stmmac_rst);
-	if (phymode == PHY_INTERFACE_MODE_SGMII) {
-		if (tse_pcs_init(dwmac->pcs.tse_pcs_base, &dwmac->pcs) != 0) {
-			dev_err(dwmac->dev, "Unable to initialize TSE PCS");
-			return -EINVAL;
-		}
-	}
+	if (phymode == PHY_INTERFACE_MODE_SGMII)
+		socfpga_sgmii_config(dwmac, true);
 	return 0;
 }
 
@@ -386,6 +388,7 @@ static int socfpga_dwmac_probe(struct platform_device *pdev)
 	struct net_device	*ndev;
 	struct stmmac_priv	*stpriv;
 	const struct socfpga_dwmac_ops *ops;
+	struct regmap_config pcs_regmap_cfg;
 
 	ops = device_get_match_data(&pdev->dev);
 	if (!ops) {
@@ -443,6 +446,44 @@ static int socfpga_dwmac_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_dvr_remove;
 
+	memset(&pcs_regmap_cfg, 0, sizeof(pcs_regmap_cfg));
+	pcs_regmap_cfg.reg_bits = 16;
+	pcs_regmap_cfg.val_bits = 16;
+	pcs_regmap_cfg.reg_shift = REGMAP_UPSHIFT(1);
+
+	/* Create a regmap for the PCS so that it can be used by the PCS driver,
+	 * if we have such a PCS
+	 */
+	if (dwmac->tse_pcs_base) {
+		struct mdio_regmap_config mrc;
+		struct regmap *pcs_regmap;
+		struct mii_bus *pcs_bus;
+
+		pcs_regmap = devm_regmap_init_mmio(&pdev->dev, dwmac->tse_pcs_base,
+						   &pcs_regmap_cfg);
+		if (IS_ERR(pcs_regmap)) {
+			ret = PTR_ERR(pcs_regmap);
+			goto err_dvr_remove;
+		}
+
+		mrc.regmap = pcs_regmap;
+		mrc.parent = &pdev->dev;
+		mrc.valid_addr = 0x0;
+
+		snprintf(mrc.name, MII_BUS_ID_SIZE, "%s-pcs-mii", ndev->name);
+		pcs_bus = devm_mdio_regmap_register(&pdev->dev, &mrc);
+		if (IS_ERR(pcs_bus)) {
+			ret = PTR_ERR(pcs_bus);
+			goto err_dvr_remove;
+		}
+
+		stpriv->hw->lynx_pcs = lynx_pcs_create_mdiodev(pcs_bus, 0);
+		if (IS_ERR(stpriv->hw->lynx_pcs)) {
+			ret = PTR_ERR(stpriv->hw->lynx_pcs);
+			goto err_dvr_remove;
+		}
+	}
+
 	return 0;
 
 err_dvr_remove:

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -937,10 +937,13 @@ static struct phylink_pcs *stmmac_mac_select_pcs(struct phylink_config *config,
 {
 	struct stmmac_priv *priv = netdev_priv(to_net_dev(config->dev));
 
-	if (!priv->hw->xpcs)
-		return NULL;
+	if (priv->hw->xpcs)
+		return &priv->hw->xpcs->pcs;
+
+	if (priv->hw->lynx_pcs)
+		return priv->hw->lynx_pcs;
 
-	return &priv->hw->xpcs->pcs;
+	return NULL;
 }
 
 static void stmmac_mac_config(struct phylink_config *config, unsigned int mode,
@@ -3813,7 +3816,8 @@ static int __stmmac_open(struct net_device *dev,
 	if (priv->hw->pcs != STMMAC_PCS_TBI &&
 	    priv->hw->pcs != STMMAC_PCS_RTBI &&
 	    (!priv->hw->xpcs ||
-	     xpcs_get_an_mode(priv->hw->xpcs, mode) != DW_AN_C73)) {
+	     xpcs_get_an_mode(priv->hw->xpcs, mode) != DW_AN_C73) &&
+	    !priv->hw->lynx_pcs) {
 		ret = stmmac_init_phy(dev);
 		if (ret) {
 			netdev_err(priv->dev,

drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c

@@ -665,6 +665,9 @@ int stmmac_mdio_unregister(struct net_device *ndev)
 	if (priv->hw->xpcs)
 		xpcs_destroy(priv->hw->xpcs);
 
+	if (priv->hw->lynx_pcs)
+		lynx_pcs_destroy(priv->hw->lynx_pcs);
+
 	mdiobus_unregister(priv->mii);
 	priv->mii->priv = NULL;
 	mdiobus_free(priv->mii);