linux-kernel - [PATCH net-next v1 1/3] net: phy: micrel: add MDI/MDI-X control support for KSZ9477 switch-integrated PHYs

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Message-Id: <20250610091354.4060454-2-o.rempel@pengutronix.de>
Date: Tue, 10 Jun 2025 11:13:52 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	Russell King <linux@...linux.org.uk>,
	netdev@...r.kernel.org
Subject: [PATCH net-next v1 1/3] net: phy: micrel: add MDI/MDI-X control support for KSZ9477 switch-integrated PHYs

Add MDI/MDI-X configuration support for PHYs integrated in the KSZ9477
family of Ethernet switches.

All MDI/MDI-X configuration modes are supported:
  - Automatic MDI/MDI-X (ETH_TP_MDI_AUTO)
  - Forced MDI (ETH_TP_MDI)
  - Forced MDI-X (ETH_TP_MDI_X)

However, when operating in automatic mode, the PHY does not expose the
resolved crossover status (i.e., whether MDI or MDI-X is active).
Therefore, in auto mode, the driver reports ETH_TP_MDI_INVALID as
the current status.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/phy/micrel.c | 59 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 64aa03aed770..a51010e64444 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1948,6 +1948,56 @@ static int ksz886x_read_status(struct phy_device *phydev)
 	return genphy_read_status(phydev);
 }
 
+static int ksz9477_mdix_update(struct phy_device *phydev)
+{
+	if (phydev->mdix_ctrl != ETH_TP_MDI_AUTO)
+		phydev->mdix = phydev->mdix_ctrl;
+	else
+		phydev->mdix = ETH_TP_MDI_INVALID;
+
+	return 0;
+}
+
+static int ksz9477_read_mdix_ctrl(struct phy_device *phydev)
+{
+	int val;
+
+	val = phy_read(phydev, MII_KSZ9131_AUTO_MDIX);
+	if (val < 0)
+		return val;
+
+	if (!(val & MII_KSZ9131_AUTO_MDIX_SWAP_OFF))
+		phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
+	else if (val & MII_KSZ9131_AUTO_MDI_SET)
+		phydev->mdix_ctrl = ETH_TP_MDI;
+	else
+		phydev->mdix_ctrl = ETH_TP_MDI_X;
+
+	return 0;
+}
+
+static int ksz9477_read_status(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = ksz9477_mdix_update(phydev);
+	if (ret)
+		return ret;
+
+	return genphy_read_status(phydev);
+}
+
+static int ksz9477_config_aneg(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = ksz9131_config_mdix(phydev, phydev->mdix_ctrl);
+	if (ret)
+		return ret;
+
+	return genphy_config_aneg(phydev);
+}
+
 struct ksz9477_errata_write {
 	u8 dev_addr;
 	u8 reg_addr;
@@ -2029,6 +2079,13 @@ static int ksz9477_config_init(struct phy_device *phydev)
 			return err;
 	}
 
+	/* Read initial MDI-X config state. So, we do not need to poll it
+	 * later on.
+	 */
+	err = ksz9477_read_mdix_ctrl(phydev);
+	if (err)
+		return err;
+
 	return kszphy_config_init(phydev);
 }
 
@@ -5691,6 +5748,8 @@ static struct phy_driver ksphy_driver[] = {
 	/* PHY_GBIT_FEATURES */
 	.config_init	= ksz9477_config_init,
 	.config_intr	= kszphy_config_intr,
+	.config_aneg	= ksz9477_config_aneg,
+	.read_status	= ksz9477_read_status,
 	.handle_interrupt = kszphy_handle_interrupt,
 	.suspend	= genphy_suspend,
 	.resume		= ksz9477_resume,
-- 
2.39.5