net: ethernet: ti: am65-cpsw: Add support for SGMII mode

Add support for configuring the CPSW Ethernet Switch in SGMII mode.

Depending on the SoC, allow selecting SGMII mode as a supported interface,
based on the compatible used.
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/ti/am65-cpsw-nuss.c

@@ -76,6 +76,7 @@
 #define AM65_CPSW_PORTN_REG_TS_CTL_LTYPE2       0x31C
 
 #define AM65_CPSW_SGMII_CONTROL_REG		0x010
+#define AM65_CPSW_SGMII_MR_ADV_ABILITY_REG	0x018
 #define AM65_CPSW_SGMII_CONTROL_MR_AN_ENABLE	BIT(0)
 
 #define AM65_CPSW_CTL_VLAN_AWARE		BIT(1)
@@ -1496,9 +1497,14 @@ static void am65_cpsw_nuss_mac_config(struct phylink_config *config, unsigned in
 	struct am65_cpsw_port *port = container_of(slave, struct am65_cpsw_port, slave);
 	struct am65_cpsw_common *common = port->common;
 
-	if (common->pdata.extra_modes & BIT(state->interface))
+	if (common->pdata.extra_modes & BIT(state->interface)) {
+		if (state->interface == PHY_INTERFACE_MODE_SGMII)
+			writel(ADVERTISE_SGMII,
+			       port->sgmii_base + AM65_CPSW_SGMII_MR_ADV_ABILITY_REG);
+
 		writel(AM65_CPSW_SGMII_CONTROL_MR_AN_ENABLE,
 		       port->sgmii_base + AM65_CPSW_SGMII_CONTROL_REG);
+	}
 }
 
 static void am65_cpsw_nuss_mac_link_down(struct phylink_config *config, unsigned int mode,
@@ -1539,6 +1545,8 @@ static void am65_cpsw_nuss_mac_link_up(struct phylink_config *config, struct phy
 
 	if (speed == SPEED_1000)
 		mac_control |= CPSW_SL_CTL_GIG;
+	if (interface == PHY_INTERFACE_MODE_SGMII)
+		mac_control |= CPSW_SL_CTL_EXT_EN;
 	if (speed == SPEED_10 && phy_interface_mode_is_rgmii(interface))
 		/* Can be used with in band mode only */
 		mac_control |= CPSW_SL_CTL_EXT_EN;
@@ -2157,6 +2165,7 @@ am65_cpsw_nuss_init_port_ndev(struct am65_cpsw_common *common, u32 port_idx)
 		break;
 
 	case PHY_INTERFACE_MODE_QSGMII:
+	case PHY_INTERFACE_MODE_SGMII:
 		if (common->pdata.extra_modes & BIT(port->slave.phy_if)) {
 			__set_bit(port->slave.phy_if,
 				  port->slave.phylink_config.supported_interfaces);