stmmac: create of compatible mdio bus for stmmac driver

The DSA driver needs to be passed a reference to an mdio bus. Typically
the mac is configured to use a fixed link but the mdio bus still needs
to be registered so that it con configure the switch.
This patch follows the same process as the altera tse ethernet driver for
creation of the mdio bus.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 32 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
index f34fc3c81a75..fd5ddf8c4504 100644
--- a/Documentation/devicetree/bindings/net/stmmac.txt
+++ b/Documentation/devicetree/bindings/net/stmmac.txt
@@ -47,6 +47,7 @@ Optional properties:
 - snps,burst_len: The AXI burst lenth value of the AXI BUS MODE register.
 - tx-fifo-depth: See ethernet.txt file in the same directory
 - rx-fifo-depth: See ethernet.txt file in the same directory
+- mdio: with compatible = "snps,dwmac-mdio", create and register mdio bus.
 
 Examples:
 
@@ -65,4 +66,11 @@ Examples:
 		tx-fifo-depth = <16384>;
 		clocks = <&clock>;
 		clock-names = "stmmaceth";
+		mdio0 {
+			#address-cells = <1>;
+			#size-cells = <0>;
+			compatible = "snps,dwmac-mdio";
+			phy1: ethernet-phy@0 {
+			};
+		};
 	};
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index bba670c42e37..16c85ccd1762 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -29,7 +29,7 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_gpio.h>
-
+#include <linux/of_mdio.h>
 #include <asm/io.h>
 
 #include "stmmac.h"
@@ -200,10 +200,29 @@ int stmmac_mdio_register(struct net_device *ndev)
 	struct stmmac_priv *priv = netdev_priv(ndev);
 	struct stmmac_mdio_bus_data *mdio_bus_data = priv->plat->mdio_bus_data;
 	int addr, found;
+	struct device_node *mdio_node = NULL;
+	struct device_node *child_node = NULL;
 
 	if (!mdio_bus_data)
 		return 0;
 
+	if (IS_ENABLED(CONFIG_OF)) {
+		for_each_child_of_node(priv->device->of_node, child_node) {
+			if (of_device_is_compatible(child_node,
+						    "snps,dwmac-mdio")) {
+				mdio_node = child_node;
+				break;
+			}
+		}
+
+		if (mdio_node) {
+			netdev_dbg(ndev, "FOUND MDIO subnode\n");
+		} else {
+			netdev_err(ndev, "NO MDIO subnode\n");
+			return 0;
+		}
+	}
+
 	new_bus = mdiobus_alloc();
 	if (new_bus == NULL)
 		return -ENOMEM;
@@ -231,7 +250,8 @@ int stmmac_mdio_register(struct net_device *ndev)
 	new_bus->irq = irqlist;
 	new_bus->phy_mask = mdio_bus_data->phy_mask;
 	new_bus->parent = priv->device;
-	err = mdiobus_register(new_bus);
+
+	err = of_mdiobus_register(new_bus, mdio_node);
 	if (err != 0) {
 		pr_err("%s: Cannot register as MDIO bus\n", new_bus->name);
 		goto bus_register_fail;
@@ -284,7 +304,7 @@ int stmmac_mdio_register(struct net_device *ndev)
 		}
 	}
 
-	if (!found) {
+	if (!found && !mdio_node) {
 		pr_warn("%s: No PHY found\n", ndev->name);
 		mdiobus_unregister(new_bus);
 		mdiobus_free(new_bus);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index d02691ba3d7f..6a52fa18cbf2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -146,7 +146,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 	if (of_property_read_u32(np, "snps,phy-addr", &plat->phy_addr) == 0)
 		dev_warn(&pdev->dev, "snps,phy-addr property is deprecated\n");
 
-	if (plat->phy_node || plat->phy_bus_name)
+	if ((plat->phy_node && !of_phy_is_fixed_link(np)) || plat->phy_bus_name)
 		plat->mdio_bus_data = NULL;
 	else
 		plat->mdio_bus_data =