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From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Vladimir Oltean <olteanv@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>
Cc:     Oleksij Rempel <o.rempel@pengutronix.de>, kernel@pengutronix.de,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Russell King <linux@armlinux.org.uk>,
        Michael Grzeschik <m.grzeschik@pengutronix.de>
Subject: [PATCH net-next v4 5/9] net: phy/dsa micrel/ksz886x add MDI-X support
Date:   Fri, 11 Jun 2021 09:15:23 +0200
Message-Id: <20210611071527.9333-6-o.rempel@pengutronix.de>
In-Reply-To: <20210611071527.9333-1-o.rempel@pengutronix.de>
References: <20210611071527.9333-1-o.rempel@pengutronix.de>
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Add support for MDI-X status and configuration

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/dsa/microchip/ksz8795.c |  5 ++
 drivers/net/phy/micrel.c            | 88 +++++++++++++++++++++++++++++
 include/linux/micrel_phy.h          |  2 +
 3 files changed, 95 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index cfa2a5000cd3..690304c87b02 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -816,6 +816,11 @@ static void ksz8_r_phy(struct ksz_device *dev, u16 phy, u16 reg, u16 *val)
 		if (data & ~LPA_SLCT)
 			data |= LPA_LPACK;
 		break;
+	case PHY_REG_PHY_CTRL:
+		ksz_pread8(dev, p, regs[P_LINK_STATUS], &link);
+		if (link & PORT_MDIX_STATUS)
+			data |= KSZ886X_CTRL_MDIX_STAT;
+		break;
 	default:
 		processed = false;
 		break;
diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index e462e718d68e..c421c1e7dd71 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1048,6 +1048,92 @@ static int ksz8873mll_config_aneg(struct phy_device *phydev)
 	return 0;
 }
 
+static int ksz886x_config_mdix(struct phy_device *phydev, u8 ctrl)
+{
+	u16 val;
+
+	switch (ctrl) {
+	case ETH_TP_MDI:
+		val = KSZ886X_BMCR_DISABLE_AUTO_MDIX;
+		break;
+	case ETH_TP_MDI_X:
+		/* Note: The naming of the bit KSZ886X_BMCR_FORCE_MDI is bit
+		 * counter intuitive, the "-X" in "1 = Force MDI" in the data
+		 * sheet seems to be missing:
+		 * 1 = Force MDI (sic!) (transmit on RX+/RX- pins)
+		 * 0 = Normal operation (transmit on TX+/TX- pins)
+		 */
+		val = KSZ886X_BMCR_DISABLE_AUTO_MDIX | KSZ886X_BMCR_FORCE_MDI;
+		break;
+	case ETH_TP_MDI_AUTO:
+		val = 0;
+		break;
+	default:
+		return 0;
+	}
+
+	return phy_modify(phydev, MII_BMCR,
+			  KSZ886X_BMCR_HP_MDIX | KSZ886X_BMCR_FORCE_MDI |
+			  KSZ886X_BMCR_DISABLE_AUTO_MDIX,
+			  KSZ886X_BMCR_HP_MDIX | val);
+}
+
+static int ksz886x_config_aneg(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = genphy_config_aneg(phydev);
+	if (ret)
+		return ret;
+
+	/* The MDI-X configuration is automatically changed by the PHY after
+	 * switching from autoneg off to on. So, take MDI-X configuration under
+	 * own control and set it after autoneg configuration was done.
+	 */
+	return ksz886x_config_mdix(phydev, phydev->mdix_ctrl);
+}
+
+static int ksz886x_mdix_update(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = phy_read(phydev, MII_BMCR);
+	if (ret < 0)
+		return ret;
+
+	if (ret & KSZ886X_BMCR_DISABLE_AUTO_MDIX) {
+		if (ret & KSZ886X_BMCR_FORCE_MDI)
+			phydev->mdix_ctrl = ETH_TP_MDI_X;
+		else
+			phydev->mdix_ctrl = ETH_TP_MDI;
+	} else {
+		phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
+	}
+
+	ret = phy_read(phydev, MII_KSZPHY_CTRL);
+	if (ret < 0)
+		return ret;
+
+	/* Same reverse logic as KSZ886X_BMCR_FORCE_MDI */
+	if (ret & KSZ886X_CTRL_MDIX_STAT)
+		phydev->mdix = ETH_TP_MDI_X;
+	else
+		phydev->mdix = ETH_TP_MDI;
+
+	return 0;
+}
+
+static int ksz886x_read_status(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = ksz886x_mdix_update(phydev);
+	if (ret < 0)
+		return ret;
+
+	return genphy_read_status(phydev);
+}
+
 static int ksz886x_resume(struct phy_device *phydev)
 {
 	int ret;
@@ -1420,6 +1506,8 @@ static struct phy_driver ksphy_driver[] = {
 	.name		= "Micrel KSZ8851 Ethernet MAC or KSZ886X Switch",
 	/* PHY_BASIC_FEATURES */
 	.config_init	= kszphy_config_init,
+	.config_aneg	= ksz886x_config_aneg,
+	.read_status	= ksz886x_read_status,
 	.suspend	= genphy_suspend,
 	.resume		= ksz886x_resume,
 }, {
diff --git a/include/linux/micrel_phy.h b/include/linux/micrel_phy.h
index b03e2afcb53f..58370abd9f4f 100644
--- a/include/linux/micrel_phy.h
+++ b/include/linux/micrel_phy.h
@@ -58,4 +58,6 @@
 #define KSZ886X_BMCR_DISABLE_TRANSMIT		BIT(1)
 #define KSZ886X_BMCR_DISABLE_LED		BIT(0)
 
+#define KSZ886X_CTRL_MDIX_STAT			BIT(4)
+
 #endif /* _MICREL_PHY_H */
-- 
2.29.2