[PATCH net-next 3/5] net: phy: Add support for the ADIN1140 PHY

[Ciprian Regus via B4 Relay <devnull+ciprian.regus.analog.com@kernel.org>]

From: Ciprian Regus <ciprian.regus@analog.com>

Add a driver for the ADIN1140's internal 10BASE-T1S PHY. The device
doesn't implement autonegotiation, so the link is always reported as
being up. Since the PHY has no link-change interrupts and the link is
always up, we set phydev->irq = PHY_MAC_INTERRUPT to prevent phylib from
polling the link state.

The device implements both C22 and C45 MDIO access methods, but can only
be discovered over C22, since the C45 MMD devices lack the MDIO_DEVID1 and
MDIO_DEVID2 registers. The indirect C45 over C22 feature is not
supported.

Signed-off-by: Ciprian Regus <ciprian.regus@analog.com>
---
 MAINTAINERS                |   7 ++++
 drivers/net/phy/Kconfig    |   6 +++
 drivers/net/phy/Makefile   |   1 +
 drivers/net/phy/adin1140.c | 102 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 116 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 27a073f53cea..1e58da5ef47a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1843,6 +1843,13 @@ S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	drivers/dma/dma-axi-dmac.c
 
+ANALOG DEVICES INC ETHERNET PHY DRIVERS
+M:	Ciprian Regus <ciprian.regus@analog.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+W:	https://ez.analog.com/linux-software-drivers
+F:	drivers/net/phy/adin1140.c
+
 ANALOG DEVICES INC IIO DRIVERS
 M:	Lars-Peter Clausen <lars@metafoo.de>
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index b5ee338b620d..fa5cd59a3825 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -124,6 +124,12 @@ config ADIN1100_PHY
 	  Currently supports the:
 	  - ADIN1100 - Robust,Industrial, Low Power 10BASE-T1L Ethernet PHY
 
+config ADIN1140_PHY
+	tristate "Analog Devices ADIN1140 10BASE-T1S PHY"
+	help
+	  Adds support for the Analog Devices, Inc. ADIN1140's internal
+	  10BASE-T1S PHY.
+
 config AMCC_QT2025_PHY
 	tristate "AMCC QT2025 PHY"
 	depends on RUST_PHYLIB_ABSTRACTIONS
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 05e4878af27a..2519364bc334 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -29,6 +29,7 @@ obj-y				+= $(sfp-obj-y) $(sfp-obj-m)
 
 obj-$(CONFIG_ADIN_PHY)		+= adin.o
 obj-$(CONFIG_ADIN1100_PHY)	+= adin1100.o
+obj-$(CONFIG_ADIN1140_PHY)	+= adin1140.o
 obj-$(CONFIG_AIR_EN8811H_PHY)   += air_en8811h.o
 obj-$(CONFIG_AMD_PHY)		+= amd.o
 obj-$(CONFIG_AMCC_QT2025_PHY)	+= qt2025.o
diff --git a/drivers/net/phy/adin1140.c b/drivers/net/phy/adin1140.c
new file mode 100644
index 000000000000..3244107ce9ef
--- /dev/null
+++ b/drivers/net/phy/adin1140.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for Analog Devices, Inc. ADIN1140 10BASE-T1S PHY
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define ADIN1140_PHY_ID		0x0283be00
+
+#define ADIN1140_PCS_CTRL		0x08f3
+#define ADIN1140_PCS_CTRL_LOOPBACK	BIT(14)
+
+static int adin1140_phy_read_mmd(struct phy_device *phydev, int devnum,
+				 u16 regnum)
+{
+	struct mii_bus *bus = phydev->mdio.bus;
+	int addr = phydev->mdio.addr;
+
+	return __mdiobus_c45_read(bus, addr, devnum, regnum);
+}
+
+static int adin1140_phy_write_mmd(struct phy_device *phydev, int devnum,
+				  u16 regnum, u16 val)
+{
+	struct mii_bus *bus = phydev->mdio.bus;
+	int addr = phydev->mdio.addr;
+
+	return __mdiobus_c45_write(bus, addr, devnum, regnum, val);
+}
+
+static int adin1140_config_init(struct phy_device *phydev)
+{
+	/* The link status of the PHY doesn't need to be polled, because
+	 * the device doesn't implement AN and there is no other mechanism
+	 * to report the link state.
+	 */
+	phydev->irq = PHY_MAC_INTERRUPT;
+
+	return 0;
+}
+
+static int adin1140_config_aneg(struct phy_device *phydev)
+{
+	/* phylib tries to clear BIT(12) in MDIO_CTRL1, since AN is disabled.
+	 * However, on the ADIN1140, that field is non-standard, being used
+	 * to control the reset status of the PHY (thus it needs to remain set).
+	 */
+	return 0;
+}
+
+static int adin1140_loopback(struct phy_device *phydev, bool enable, int speed)
+{
+	if (enable && speed)
+		return -EOPNOTSUPP;
+
+	return phy_modify_mmd(phydev, MDIO_MMD_PCS, ADIN1140_PCS_CTRL,
+			      ADIN1140_PCS_CTRL_LOOPBACK,
+			      enable ? ADIN1140_PCS_CTRL_LOOPBACK : 0);
+}
+
+static int adin1140_read_status(struct phy_device *phydev)
+{
+	phydev->link = 1;
+	phydev->duplex = DUPLEX_HALF;
+	phydev->speed = SPEED_10;
+	phydev->autoneg = AUTONEG_DISABLE;
+
+	return 0;
+}
+
+static struct phy_driver adin1140_driver[] = {
+	{
+		PHY_ID_MATCH_EXACT(ADIN1140_PHY_ID),
+		.name = "ADIN1140",
+		.features = PHY_BASIC_T1S_P2MP_FEATURES,
+		.read_status = adin1140_read_status,
+		.config_init = adin1140_config_init,
+		.config_aneg = adin1140_config_aneg,
+		.set_loopback = adin1140_loopback,
+		.read_mmd = adin1140_phy_read_mmd,
+		.write_mmd = adin1140_phy_write_mmd,
+		.get_plca_cfg = genphy_c45_plca_get_cfg,
+		.set_plca_cfg = genphy_c45_plca_set_cfg,
+		.get_plca_status = genphy_c45_plca_get_status,
+	},
+};
+module_phy_driver(adin1140_driver);
+
+static const struct mdio_device_id __maybe_unused adin1140_tbl[] = {
+	{ PHY_ID_MATCH_EXACT(ADIN1140_PHY_ID) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, adin1140_tbl);
+
+MODULE_DESCRIPTION("Analog Devices, Inc. ADIN1140 10BASE-T1S PHY");
+MODULE_AUTHOR("Ciprian Regus <ciprian.regus@analog.com>");
+MODULE_LICENSE("GPL");

-- 
2.43.0