[PATCH net-next 3/4] drivers/net/phy: Add driver for the onsemi NCN26000 10BASE-T1S PHY

[Piergiorgio Beruto]

Add support for the onsemi NCN26000 10BASE-T1S industrial Ethernet PHY.
The driver supports Point-to-Multipoint operation without
auto-negotiation and with link control handling. The PLCA RS support
will be included on a separate patch.

Signed-off-by: Piergiorgio Beruto <piergiorgio.beruto@xxxxxxxxx>
---
 MAINTAINERS                |   7 ++
 drivers/net/phy/Kconfig    |   7 ++
 drivers/net/phy/Makefile   |   1 +
 drivers/net/phy/ncn26000.c | 193 +++++++++++++++++++++++++++++++++++++
 4 files changed, 208 insertions(+)
 create mode 100644 drivers/net/phy/ncn26000.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 7952243e4b43..f07527baf321 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15357,6 +15357,13 @@ L:	linux-mips@xxxxxxxxxxxxxxx
 S:	Maintained
 F:	arch/mips/boot/dts/ralink/omega2p.dts
 
+ONSEMI ETHERNET PHY DRIVERS
+M:	Piergiorgio Beruto <piergiorgio.beruto@xxxxxxxxx>
+L:	netdev@xxxxxxxxxxxxxxx
+S:	Supported
+W:	http://www.onsemi.com
+F:	drivers/net/phy/ncn*
+
 OP-TEE DRIVER
 M:	Jens Wiklander <jens.wiklander@xxxxxxxxxx>
 L:	op-tee@xxxxxxxxxxxxxxxxxxxxxxxxx
diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index af00cf44cd97..7c466830c611 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -267,6 +267,13 @@ config NATIONAL_PHY
 	help
 	  Currently supports the DP83865 PHY.
 
+config NCN26000_PHY
+	tristate "onsemi 10BASE-T1S Ethernet PHY"
+	help
+	  Adds support for the onsemi 10BASE-T1S Ethernet PHY.
+	  Currently supports the NCN26000 10BASE-T1S Industrial PHY
+	  with MII interface.
+
 config NXP_C45_TJA11XX_PHY
 	tristate "NXP C45 TJA11XX PHYs"
 	depends on PTP_1588_CLOCK_OPTIONAL
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index f7138d3c896b..b5138066ba04 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -77,6 +77,7 @@ obj-$(CONFIG_MICROCHIP_T1_PHY)	+= microchip_t1.o
 obj-$(CONFIG_MICROSEMI_PHY)	+= mscc/
 obj-$(CONFIG_MOTORCOMM_PHY)	+= motorcomm.o
 obj-$(CONFIG_NATIONAL_PHY)	+= national.o
+obj-$(CONFIG_NCN26000_PHY)	+= ncn26000.o
 obj-$(CONFIG_NXP_C45_TJA11XX_PHY)	+= nxp-c45-tja11xx.o
 obj-$(CONFIG_NXP_TJA11XX_PHY)	+= nxp-tja11xx.o
 obj-$(CONFIG_QSEMI_PHY)		+= qsemi.o
diff --git a/drivers/net/phy/ncn26000.c b/drivers/net/phy/ncn26000.c
new file mode 100644
index 000000000000..65a34edc5b20
--- /dev/null
+++ b/drivers/net/phy/ncn26000.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/*
+ *  Driver for Analog Devices Industrial Ethernet T1L PHYs
+ *
+ * Copyright 2020 Analog Devices Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/phy.h>
+#include <linux/property.h>
+
+#define PHY_ID_NCN26000				0x180FF5A1
+
+#define NCN26000_REG_IRQ_CTL                    ((u16)16)
+#define NCN26000_REG_IRQ_STATUS                 ((u16)17)
+
+#define NCN26000_IRQ_LINKST_BIT                 ((u16)1)
+#define NCN26000_IRQ_PLCAST_BIT                 ((u16)(1 << 1))
+#define NCN26000_IRQ_LJABBER_BIT                ((u16)(1 << 2))
+#define NCN26000_IRQ_RJABBER_BIT                ((u16)(1 << 3))
+#define NCN26000_IRQ_RJABBER_BIT                ((u16)(1 << 3))
+#define NCN26000_IRQ_PLCAREC_BIT                ((u16)(1 << 4))
+#define NCN26000_IRQ_PHYSCOL_BIT                ((u16)(1 << 5))
+
+struct ncn26000_priv {
+	u16 enabled_irqs;
+};
+
+static int ncn26000_config_init(struct phy_device *phydev)
+{
+	// TODO: add vendor-specific tuning (ENI, CMC, ...)
+	return 0;
+}
+
+static int ncn26000_enable(struct phy_device *phydev)
+{
+	phydev->mdix_ctrl = ETH_TP_MDI_AUTO;
+	phydev->mdix = ETH_TP_MDI;
+	phydev->pause = 0;
+	phydev->asym_pause = 0;
+	phydev->speed = SPEED_10;
+	phydev->duplex = DUPLEX_HALF;
+
+	// bring up the link (link_ctrl is mapped to BMCR_ANENABLE)
+	// clear also ISOLATE mode and Collision Test
+	return phy_write(phydev, MII_BMCR, BMCR_ANENABLE);
+}
+
+static int ncn26000_soft_reset(struct phy_device *phydev)
+{
+	int ret;
+
+	ret = phy_set_bits(phydev, MII_BMCR, BMCR_RESET);
+
+	if (ret != 0)
+		return ret;
+
+	return phy_read_poll_timeout(phydev,
+				     MII_BMCR,
+				     ret,
+				     !(ret & BMCR_RESET),
+				     500,
+				     20000,
+				     true);
+}
+
+static int ncn26000_get_features(struct phy_device *phydev)
+{
+	linkmode_zero(phydev->supported);
+	linkmode_set_bit(ETHTOOL_LINK_MODE_MII_BIT, phydev->supported);
+
+	linkmode_set_bit(ETHTOOL_LINK_MODE_10baseT1S_P2MP_Half_BIT,
+			 phydev->supported);
+
+	linkmode_copy(phydev->advertising, phydev->supported);
+	return 0;
+}
+
+static irqreturn_t ncn26000_handle_interrupt(struct phy_device *phydev)
+{
+	const struct ncn26000_priv *const priv = phydev->priv;
+	u16 events;
+	int ret;
+
+	// read and aknowledge the IRQ status register
+	ret = phy_read(phydev, NCN26000_REG_IRQ_STATUS);
+
+	if (unlikely(ret < 0))
+		return IRQ_NONE;
+
+	events = (u16)ret & priv->enabled_irqs;
+	if (events == 0)
+		return IRQ_NONE;
+
+	if (events & NCN26000_IRQ_LINKST_BIT) {
+		ret = phy_read(phydev, MII_BMSR);
+
+		if (unlikely(ret < 0)) {
+			phydev_err(phydev,
+				   "error reading the status register (%d)\n",
+				   ret);
+
+			return IRQ_NONE;
+		}
+
+		phydev->link = ((u16)ret & BMSR_ANEGCOMPLETE) ? 1 : 0;
+	}
+
+	// handle more IRQs here
+
+	phy_trigger_machine(phydev);
+	return IRQ_HANDLED;
+}
+
+static int ncn26000_config_intr(struct phy_device *phydev)
+{
+	int ret;
+	struct ncn26000_priv *priv = phydev->priv;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		// acknowledge IRQs
+		ret = phy_read(phydev, NCN26000_REG_IRQ_STATUS);
+		if (ret < 0)
+			return ret;
+
+		// get link status notifications
+		priv->enabled_irqs = NCN26000_IRQ_LINKST_BIT;
+	} else {
+		// disable all IRQs
+		priv->enabled_irqs = 0;
+	}
+
+	ret = phy_write(phydev, NCN26000_REG_IRQ_CTL, priv->enabled_irqs);
+	if (ret != 0)
+		return ret;
+
+	return 0;
+}
+
+static int ncn26000_probe(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct ncn26000_priv *priv;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	phydev->priv = priv;
+
+	return 0;
+}
+
+static void ncn26000_remove(struct phy_device *phydev)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct ncn26000_priv *priv = phydev->priv;
+
+	// free the private structure pointer
+	devm_kfree(dev, priv);
+}
+
+static struct phy_driver ncn26000_driver[] = {
+	{
+		PHY_ID_MATCH_MODEL(PHY_ID_NCN26000),
+		.name			= "NCN26000",
+		.probe                  = ncn26000_probe,
+		.remove                 = ncn26000_remove,
+		.get_features		= ncn26000_get_features,
+		.config_init            = ncn26000_config_init,
+		.soft_reset             = ncn26000_soft_reset,
+		.config_intr            = ncn26000_config_intr,
+		.config_aneg		= ncn26000_enable,
+		.handle_interrupt       = ncn26000_handle_interrupt,
+	},
+};
+
+module_phy_driver(ncn26000_driver);
+
+static struct mdio_device_id __maybe_unused ncn26000_tbl[] = {
+	{ PHY_ID_MATCH_MODEL(PHY_ID_NCN26000) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, ncn26000_tbl);
+MODULE_AUTHOR("Piergiorgio Beruto");
+MODULE_DESCRIPTION("onsemi 10BASE-T1S PHY driver");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.35.1