net: ethernet: ti: am65-cpsw: fix port_np reference counting

A reference to the device tree node is stored in a private struct, thus
the reference count has to be incremented. Also, decrement the count on
device removal and in the error path.

Fixes: 93a7653 ("net: ethernet: ti: introduce am65x/j721e gigabit eth subsystem driver")
Signed-off-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250414083942.4015060-1-mwalle@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -2666,7 +2666,7 @@ static int am65_cpsw_nuss_init_slave_ports(struct am65_cpsw_common *common)
 				of_property_read_bool(port_np, "ti,mac-only");
 
 		/* get phy/link info */
-		port->slave.port_np = port_np;
+		port->slave.port_np = of_node_get(port_np);
 		ret = of_get_phy_mode(port_np, &port->slave.phy_if);
 		if (ret) {
 			dev_err(dev, "%pOF read phy-mode err %d\n",
@@ -2720,6 +2720,17 @@ static void am65_cpsw_nuss_phylink_cleanup(struct am65_cpsw_common *common)
 	}
 }
 
+static void am65_cpsw_remove_dt(struct am65_cpsw_common *common)
+{
+	struct am65_cpsw_port *port;
+	int i;
+
+	for (i = 0; i < common->port_num; i++) {
+		port = &common->ports[i];
+		of_node_put(port->slave.port_np);
+	}
+}
+
 static int
 am65_cpsw_nuss_init_port_ndev(struct am65_cpsw_common *common, u32 port_idx)
 {
@@ -3622,6 +3633,7 @@ static int am65_cpsw_nuss_probe(struct platform_device *pdev)
 	am65_cpsw_nuss_cleanup_ndev(common);
 	am65_cpsw_nuss_phylink_cleanup(common);
 	am65_cpts_release(common->cpts);
+	am65_cpsw_remove_dt(common);
 err_of_clear:
 	if (common->mdio_dev)
 		of_platform_device_destroy(common->mdio_dev, NULL);
@@ -3661,6 +3673,7 @@ static void am65_cpsw_nuss_remove(struct platform_device *pdev)
 	am65_cpsw_nuss_phylink_cleanup(common);
 	am65_cpts_release(common->cpts);
 	am65_cpsw_disable_serdes_phy(common);
+	am65_cpsw_remove_dt(common);
 
 	if (common->mdio_dev)
 		of_platform_device_destroy(common->mdio_dev, NULL);