net: lan743x: add support for RMII interface

Enable RMII interface in the lan743x driver for PHY and MAC
configuration.

- Select RMII interface in lan743x_phy_interface_select().
- Update phylink supported_interfaces and MAC capabilities.
- Enable RMII via RMII_CTL in lan743x_hardware_init().
- Define RMII_CTL register and enable bit in lan743x_main.h.

EEE is not supported with RMII on PCI11x1x: the hardware does not
implement LPI signaling over RMII. Clear RMII from lpi_interfaces to
prevent phylink from enabling EEE on this interface.

Signed-off-by: Thangaraj Samynathan <thangaraj.s@microchip.com>
Link: https://patch.msgid.link/20260723050827.694832-3-Thangaraj.S@microchip.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 24 insertions, 2 deletions

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index 3a418105cd11..24ae56a3c9ed 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -1402,6 +1402,8 @@ static void lan743x_phy_interface_select(struct lan743x_adapter *adapter)
 
 	if (adapter->is_pci11x1x && adapter->is_sgmii_en)
 		adapter->phy_interface = PHY_INTERFACE_MODE_SGMII;
+	else if (adapter->is_pci11x1x && adapter->is_rmii_en)
+		adapter->phy_interface = PHY_INTERFACE_MODE_RMII;
 	else if (id_rev == ID_REV_ID_LAN7430_)
 		adapter->phy_interface = PHY_INTERFACE_MODE_GMII;
 	else if ((id_rev == ID_REV_ID_LAN7431_) && (data & MAC_CR_MII_EN_))
@@ -3190,6 +3192,12 @@ static int lan743x_phylink_create(struct lan743x_adapter *adapter)
 		__set_bit(PHY_INTERFACE_MODE_MII,
 			  adapter->phylink_config.supported_interfaces);
 		break;
+	case PHY_INTERFACE_MODE_RMII:
+		__set_bit(PHY_INTERFACE_MODE_RMII,
+			  adapter->phylink_config.supported_interfaces);
+		adapter->phylink_config.lpi_capabilities = 0;
+		break;
+
 	default:
 		phy_interface_set_rgmii(adapter->phylink_config.supported_interfaces);
 	}
@@ -3197,6 +3205,9 @@ static int lan743x_phylink_create(struct lan743x_adapter *adapter)
 	memcpy(adapter->phylink_config.lpi_interfaces,
 	       adapter->phylink_config.supported_interfaces,
 	       sizeof(adapter->phylink_config.lpi_interfaces));
+	if (adapter->phy_interface == PHY_INTERFACE_MODE_RMII)
+		__clear_bit(PHY_INTERFACE_MODE_RMII,
+			    adapter->phylink_config.lpi_interfaces);
 
 	pl = phylink_create(&adapter->phylink_config, NULL,
 			    adapter->phy_interface, &lan743x_phylink_mac_ops);
@@ -3541,6 +3552,7 @@ static int lan743x_hardware_init(struct lan743x_adapter *adapter,
 {
 	struct lan743x_tx *tx;
 	u32 sgmii_ctl;
+	u32 rmii_ctl;
 	int index;
 	int ret;
 
@@ -3562,6 +3574,12 @@ static int lan743x_hardware_init(struct lan743x_adapter *adapter,
 			sgmii_ctl |= SGMII_CTL_SGMII_POWER_DN_;
 		}
 		lan743x_csr_write(adapter, SGMII_CTL, sgmii_ctl);
+		rmii_ctl = lan743x_csr_read(adapter, RMII_CTL);
+		if (adapter->is_rmii_en)
+			rmii_ctl |= RMII_CTL_RMII_ENABLE_;
+		else
+			rmii_ctl &= ~RMII_CTL_RMII_ENABLE_;
+		lan743x_csr_write(adapter, RMII_CTL, rmii_ctl);
 	} else {
 		adapter->max_tx_channels = LAN743X_MAX_TX_CHANNELS;
 		adapter->used_tx_channels = LAN743X_USED_TX_CHANNELS;
@@ -3628,8 +3646,9 @@ static int lan743x_mdiobus_init(struct lan743x_adapter *adapter)
 			adapter->mdiobus->name = "lan743x-mdiobus-c45";
 			dev_dbg(&adapter->pdev->dev, "lan743x-mdiobus-c45\n");
 		} else {
-			dev_dbg(&adapter->pdev->dev, "RGMII operation\n");
-			// Only C22 support when RGMII I/F
+			dev_dbg(&adapter->pdev->dev, "%s operation\n",
+				adapter->is_rmii_en ? "RMII" : "RGMII");
+			// Only C22 support when RGMII/RMII I/F
 			adapter->mdiobus->read = lan743x_mdiobus_read_c22;
 			adapter->mdiobus->write = lan743x_mdiobus_write_c22;
 			adapter->mdiobus->name = "lan743x-mdiobus";
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index 1f8d9294a6ef..d9495cf96b41 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -325,6 +325,9 @@
 #define MAC_WUCSR2_IPV6_TCPSYN_RCD_	BIT(5)
 #define MAC_WUCSR2_IPV4_TCPSYN_RCD_	BIT(4)
 
+#define RMII_CTL			(0x710)
+#define RMII_CTL_RMII_ENABLE_		BIT(0)
+
 #define SGMII_ACC			(0x720)
 #define SGMII_ACC_SGMII_BZY_		BIT(31)
 #define SGMII_ACC_SGMII_WR_		BIT(30)