net: phy: marvell-88q2xxx: add driver for the Marvell 88Q2110 PHY

Add a driver for the Marvell 88Q2110. This driver allows to detect the
link, switch between 100BASE-T1 and 1000BASE-T1 and switch between
master and slave mode. Autonegotiation supported by the PHY does not yet
work.

Signed-off-by: Stefan Eichenberger <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/phy/Kconfig

···
 	help
 	  Support for the Marvell Alaska MV88X3310 and compatible PHYs.
 
+config MARVELL_88Q2XXX_PHY
+	tristate "Marvell 88Q2XXX PHY"
+	help
+	  Support for the Marvell 88Q2XXX 100/1000BASE-T1 Automotive Ethernet
+	  PHYs.
+
 config MARVELL_88X2222_PHY
 	tristate "Marvell 88X2222 PHY"
 	help

drivers/net/phy/Makefile

···
 obj-$(CONFIG_LXT_PHY)		+= lxt.o
 obj-$(CONFIG_MARVELL_10G_PHY)	+= marvell10g.o
 obj-$(CONFIG_MARVELL_PHY)	+= marvell.o
+obj-$(CONFIG_MARVELL_88Q2XXX_PHY)	+= marvell-88q2xxx.o
 obj-$(CONFIG_MARVELL_88X2222_PHY)	+= marvell-88x2222.o
 obj-$(CONFIG_MAXLINEAR_GPHY)	+= mxl-gpy.o
 obj-$(CONFIG_MEDIATEK_GE_PHY)	+= mediatek-ge.o

drivers/net/phy/marvell-88q2xxx.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Marvell 88Q2XXX automotive 100BASE-T1/1000BASE-T1 PHY driver
+ */
+#include <linux/ethtool_netlink.h>
+#include <linux/marvell_phy.h>
+#include <linux/phy.h>
+
+#define MDIO_MMD_AN_MV_STAT			32769
+#define MDIO_MMD_AN_MV_STAT_ANEG		0x0100
+#define MDIO_MMD_AN_MV_STAT_LOCAL_RX		0x1000
+#define MDIO_MMD_AN_MV_STAT_REMOTE_RX		0x2000
+#define MDIO_MMD_AN_MV_STAT_LOCAL_MASTER	0x4000
+#define MDIO_MMD_AN_MV_STAT_MS_CONF_FAULT	0x8000
+
+#define MDIO_MMD_PCS_MV_100BT1_STAT1			33032
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_IDLE_ERROR	0x00FF
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_JABBER		0x0100
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_LINK		0x0200
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_LOCAL_RX		0x1000
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_REMOTE_RX		0x2000
+#define MDIO_MMD_PCS_MV_100BT1_STAT1_LOCAL_MASTER	0x4000
+
+#define MDIO_MMD_PCS_MV_100BT1_STAT2		33033
+#define MDIO_MMD_PCS_MV_100BT1_STAT2_JABBER	0x0001
+#define MDIO_MMD_PCS_MV_100BT1_STAT2_POL	0x0002
+#define MDIO_MMD_PCS_MV_100BT1_STAT2_LINK	0x0004
+#define MDIO_MMD_PCS_MV_100BT1_STAT2_ANGE	0x0008
+
+static int mv88q2xxx_soft_reset(struct phy_device *phydev)
+{
+	int ret;
+	int val;
+
+	ret = phy_write_mmd(phydev, MDIO_MMD_PCS,
+			    MDIO_PCS_1000BT1_CTRL, MDIO_PCS_1000BT1_CTRL_RESET);
+	if (ret < 0)
+		return ret;
+
+	return phy_read_mmd_poll_timeout(phydev, MDIO_MMD_PCS,
+					 MDIO_PCS_1000BT1_CTRL, val,
+					 !(val & MDIO_PCS_1000BT1_CTRL_RESET),
+					 50000, 600000, true);
+}
+
+static int mv88q2xxx_read_link_gbit(struct phy_device *phydev)
+{
+	int ret;
+	bool link = false;
+
+	/* Read vendor specific Auto-Negotiation status register to get local
+	 * and remote receiver status according to software initialization
+	 * guide.
+	 */
+	ret = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_MMD_AN_MV_STAT);
+	if (ret < 0) {
+		return ret;
+	} else if ((ret & MDIO_MMD_AN_MV_STAT_LOCAL_RX) &&
+		   (ret & MDIO_MMD_AN_MV_STAT_REMOTE_RX)) {
+		/* The link state is latched low so that momentary link
+		 * drops can be detected. Do not double-read the status
+		 * in polling mode to detect such short link drops except
+		 * the link was already down.
+		 */
+		if (!phy_polling_mode(phydev) || !phydev->link) {
+			ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_1000BT1_STAT);
+			if (ret < 0)
+				return ret;
+			else if (ret & MDIO_PCS_1000BT1_STAT_LINK)
+				link = true;
+		}
+
+		if (!link) {
+			ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_PCS_1000BT1_STAT);
+			if (ret < 0)
+				return ret;
+			else if (ret & MDIO_PCS_1000BT1_STAT_LINK)
+				link = true;
+		}
+	}
+
+	phydev->link = link;
+
+	return 0;
+}
+
+static int mv88q2xxx_read_link_100m(struct phy_device *phydev)
+{
+	int ret;
+
+	/* The link state is latched low so that momentary link
+	 * drops can be detected. Do not double-read the status
+	 * in polling mode to detect such short link drops except
+	 * the link was already down. In case we are not polling,
+	 * we always read the realtime status.
+	 */
+	if (!phy_polling_mode(phydev) || !phydev->link) {
+		ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_MMD_PCS_MV_100BT1_STAT1);
+		if (ret < 0)
+			return ret;
+		else if (ret & MDIO_MMD_PCS_MV_100BT1_STAT1_LINK)
+			goto out;
+	}
+
+	ret = phy_read_mmd(phydev, MDIO_MMD_PCS, MDIO_MMD_PCS_MV_100BT1_STAT1);
+	if (ret < 0)
+		return ret;
+
+out:
+	/* Check if we have link and if the remote and local receiver are ok */
+	if ((ret & MDIO_MMD_PCS_MV_100BT1_STAT1_LINK) &&
+	    (ret & MDIO_MMD_PCS_MV_100BT1_STAT1_LOCAL_RX) &&
+	    (ret & MDIO_MMD_PCS_MV_100BT1_STAT1_REMOTE_RX))
+		phydev->link = true;
+	else
+		phydev->link = false;
+
+	return 0;
+}
+
+static int mv88q2xxx_read_link(struct phy_device *phydev)
+{
+	int ret;
+
+	/* The 88Q2XXX PHYs do not have the PMA/PMD status register available,
+	 * therefore we need to read the link status from the vendor specific
+	 * registers depending on the speed.
+	 */
+	if (phydev->speed == SPEED_1000)
+		ret = mv88q2xxx_read_link_gbit(phydev);
+	else
+		ret = mv88q2xxx_read_link_100m(phydev);
+
+	return ret;
+}
+
+static int mv88q2xxx_read_status(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = mv88q2xxx_read_link(phydev);
+	if (ret < 0)
+		return ret;
+
+	return genphy_c45_read_pma(phydev);
+}
+
+static int mv88q2xxx_get_features(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = genphy_c45_pma_read_abilities(phydev);
+	if (ret)
+		return ret;
+
+	/* We need to read the baset1 extended abilities manually because the
+	 * PHY does not signalize it has the extended abilities register
+	 * available.
+	 */
+	ret = genphy_c45_pma_baset1_read_abilities(phydev);
+	if (ret)
+		return ret;
+
+	/* The PHY signalizes it supports autonegotiation. Unfortunately, so
+	 * far it was not possible to get a link even when following the init
+	 * sequence provided by Marvell. Disable it for now until a proper
+	 * workaround is found or a new PHY revision is released.
+	 */
+	linkmode_clear_bit(ETHTOOL_LINK_MODE_Autoneg_BIT, phydev->supported);
+
+	return 0;
+}
+
+static int mv88q2xxx_config_aneg(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = genphy_c45_config_aneg(phydev);
+	if (ret)
+		return ret;
+
+	return mv88q2xxx_soft_reset(phydev);
+}
+
+static int mv88q2xxx_config_init(struct phy_device *phydev)
+{
+	int ret;
+
+	/* The 88Q2XXX PHYs do have the extended ability register available, but
+	 * register MDIO_PMA_EXTABLE where they should signalize it does not
+	 * work according to specification. Therefore, we force it here.
+	 */
+	phydev->pma_extable = MDIO_PMA_EXTABLE_BT1;
+
+	/* Read the current PHY configuration */
+	ret = genphy_c45_read_pma(phydev);
+	if (ret)
+		return ret;
+
+	return mv88q2xxx_config_aneg(phydev);
+}
+
+static int mv88q2xxxx_get_sqi(struct phy_device *phydev)
+{
+	int ret;
+
+	if (phydev->speed == SPEED_100) {
+		/* Read the SQI from the vendor specific receiver status
+		 * register
+		 */
+		ret = phy_read_mmd(phydev, MDIO_MMD_PCS, 0x8230);
+		if (ret < 0)
+			return ret;
+
+		ret = ret >> 12;
+	} else {
+		/* Read from vendor specific registers, they are not documented
+		 * but can be found in the Software Initialization Guide. Only
+		 * revisions >= A0 are supported.
+		 */
+		ret = phy_modify_mmd(phydev, MDIO_MMD_PCS, 0xFC5D, 0x00FF, 0x00AC);
+		if (ret < 0)
+			return ret;
+
+		ret = phy_read_mmd(phydev, MDIO_MMD_PCS, 0xfc88);
+		if (ret < 0)
+			return ret;
+	}
+
+	return ret & 0x0F;
+}
+
+static int mv88q2xxxx_get_sqi_max(struct phy_device *phydev)
+{
+	return 15;
+}
+
+static struct phy_driver mv88q2xxx_driver[] = {
+	{
+		.phy_id			= MARVELL_PHY_ID_88Q2110,
+		.phy_id_mask		= MARVELL_PHY_ID_MASK,
+		.name			= "mv88q2110",
+		.get_features		= mv88q2xxx_get_features,
+		.config_aneg		= mv88q2xxx_config_aneg,
+		.config_init		= mv88q2xxx_config_init,
+		.read_status		= mv88q2xxx_read_status,
+		.soft_reset		= mv88q2xxx_soft_reset,
+		.set_loopback		= genphy_c45_loopback,
+		.get_sqi		= mv88q2xxxx_get_sqi,
+		.get_sqi_max		= mv88q2xxxx_get_sqi_max,
+	},
+};
+
+module_phy_driver(mv88q2xxx_driver);
+
+static struct mdio_device_id __maybe_unused mv88q2xxx_tbl[] = {
+	{ MARVELL_PHY_ID_88Q2110, MARVELL_PHY_ID_MASK },
+	{ /*sentinel*/ }
+};
+MODULE_DEVICE_TABLE(mdio, mv88q2xxx_tbl);
+
+MODULE_DESCRIPTION("Marvell 88Q2XXX 100/1000BASE-T1 Automotive Ethernet PHY driver");
+MODULE_LICENSE("GPL");

include/linux/marvell_phy.h

···
 #define MARVELL_PHY_ID_88X3310		0x002b09a0
 #define MARVELL_PHY_ID_88E2110		0x002b09b0
 #define MARVELL_PHY_ID_88X2222		0x01410f10
+#define MARVELL_PHY_ID_88Q2110		0x002b0980
 
 /* Marvel 88E1111 in Finisar SFP module with modified PHY ID */
 #define MARVELL_PHY_ID_88E1111_FINISAR	0x01ff0cc0