[PATCH v1] net: phy: add TI DP83TG720 1000BaseT1 PHY support

[Oleksij Rempel <o.rempel@pengutronix.de>]

From: Oleksij Rempel <linux@rempel-privat.de>

Add driver for TI DP83TG720 driver support.

Even if the PHY is capable of creating a link on it's own. It needs
proper RGMII configuration and HW reset on link loss.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/phy/Kconfig     |   6 +++
 drivers/net/phy/Makefile    |   1 +
 drivers/net/phy/dp83tg720.c | 102 ++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+)
 create mode 100644 drivers/net/phy/dp83tg720.c

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index e95e2a3228..8e12671801 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -35,6 +35,12 @@ config DP83TD510_PHY
 	  Support for the DP83TD510 Ethernet 10Base-T1L PHY. This PHY supports
 	  a 10M single pair Ethernet connection for up to 1000 meter cable.
 
+config DP83TG720_PHY
+	tristate "Texas Instruments DP83TG720 Ethernet 1000Base-T1 PHY"
+	help
+	  Support for the DP83TG720 Ethernet 10000Base-T1 PHY. This PHY supports
+	  a 1000M single pair Ethernet.
+
 config LXT_PHY
 	bool "Driver for the Intel LXT PHYs"
 	help
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 26e4ad884d..ce15e1bab7 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -19,4 +19,5 @@ obj-$(CONFIG_MDIO_BUS_MUX)	+= mdio-mux.o
 obj-$(CONFIG_MDIO_BUS_MUX_GPIO)	+= mdio-mux-gpio.o
 obj-$(CONFIG_DP83867_PHY)	+= dp83867.o
 obj-$(CONFIG_DP83TD510_PHY)	+= dp83td510.o
+obj-$(CONFIG_DP83TG720_PHY)	+= dp83tg720.o
 
diff --git a/drivers/net/phy/dp83tg720.c b/drivers/net/phy/dp83tg720.c
new file mode 100644
index 0000000000..f0c6e29489
--- /dev/null
+++ b/drivers/net/phy/dp83tg720.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Driver for the Texas Instruments DP83TG720 PHY
+ * Copyright (c) 2023 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
+ */
+#include <common.h>
+#include <linux/mdio.h>
+#include <linux/phy.h>
+
+#define DP83TG720S_PHY_ID			0x2000a284
+
+/* MDIO_MMD_VEND2 registers */
+#define DP83TG720S_MII_REG_10			0x10
+#define DP83TG720S_LINK_STATUS			BIT(0)
+
+#define DP83TG720S_RGMII_DELAY_CTRL		0x602
+/* In RGMII mode, Enable or disable the internal delay for RXD */
+#define DP83TG720S_RGMII_RX_CLK_SEL		BIT(1)
+/* In RGMII mode, Enable or disable the internal delay for TXD */
+#define DP83TG720S_RGMII_TX_CLK_SEL		BIT(0)
+
+#define DP83TG720S_PHY_RESET			0x1f
+#define DP83TG720S_HW_RESET			BIT(15)
+
+static int dp83tg720_config_rgmii_delay(struct phy_device *phydev)
+{
+	u16 rgmii_delay_mask;
+	u16 rgmii_delay = 0;
+
+	switch (phydev->interface) {
+	case PHY_INTERFACE_MODE_RGMII:
+		rgmii_delay = 0;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_ID:
+		rgmii_delay = DP83TG720S_RGMII_RX_CLK_SEL |
+				DP83TG720S_RGMII_TX_CLK_SEL;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_RXID:
+		rgmii_delay = DP83TG720S_RGMII_RX_CLK_SEL;
+		break;
+	case PHY_INTERFACE_MODE_RGMII_TXID:
+		rgmii_delay = DP83TG720S_RGMII_TX_CLK_SEL;
+		break;
+	default:
+		return 0;
+	}
+
+	rgmii_delay_mask = DP83TG720S_RGMII_RX_CLK_SEL |
+			   DP83TG720S_RGMII_TX_CLK_SEL;
+
+	return phy_modify_mmd(phydev, MDIO_MMD_VEND2,
+			      DP83TG720S_RGMII_DELAY_CTRL, rgmii_delay_mask,
+			      rgmii_delay);
+}
+
+static int dp83tg720_phy_init(struct phy_device *phydev)
+{
+	/* HW reset is needed to recover link if previous link was lost. SW
+	 * reset is not enough.
+	 */
+	phy_write(phydev, DP83TG720S_PHY_RESET, DP83TG720S_HW_RESET);
+
+	phydev->supported = SUPPORTED_1000baseT_Full;
+	phydev->advertising = SUPPORTED_1000baseT_Full;
+
+	if (phy_interface_is_rgmii(phydev))
+		return dp83tg720_config_rgmii_delay(phydev);
+
+	return 0;
+}
+
+static int dp83tg720_read_status(struct phy_device *phydev)
+{
+	u16 phy_sts;
+
+	phy_sts = phy_read(phydev, DP83TG720S_MII_REG_10);
+	phydev->link = !!(phy_sts & DP83TG720S_LINK_STATUS);
+	if (!phydev->link) {
+		phydev->speed = SPEED_UNKNOWN;
+		phydev->duplex = DUPLEX_UNKNOWN;
+
+		/* According to the "DP83TC81x, DP83TG72x Software
+		 * Implementation Guide", the PHY needs to be reset after a
+		 * link loss or if no link is created after at least 100ms.
+		 */
+		dp83tg720_phy_init(phydev);
+		return 0;
+	}
+
+	phydev->duplex = DUPLEX_FULL;
+	phydev->speed = SPEED_1000;
+
+	return 0;
+}
+
+static struct phy_driver dp83tg720_driver[] = {
+{
+	PHY_ID_MATCH_MODEL(DP83TG720S_PHY_ID),
+	.drv.name	= "TI DP83TG720S",
+	.read_status	= dp83tg720_read_status,
+	.config_init	= dp83tg720_phy_init,
+} };
+device_phy_drivers(dp83tg720_driver);
-- 
2.39.2