generic: ar8216: add support for separated mdio bus for phy access

Atheros FE switches have a builtin mdio master available for PHY
accessing and on ar724x/ar933x builtin switches this mdio master
is the only way of accessing PHYs.

After this patch if there is phy_read/phy_write method available
in ar8xxx_chip we register a separated mdio bus for accessing PHYs.

Still adds support for mdio device probing only since this isn't
needed for those switches registered using PHY probing.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

target/linux/generic/files/drivers/net/phy/ar8216.c

@@ -190,7 +190,7 @@ ar8xxx_phy_init(struct ar8xxx_priv *priv)
 	int i;
 	struct mii_bus *bus;
 
-	bus = priv->mii_bus;
+	bus = priv->sw_mii_bus ?: priv->mii_bus;
 	for (i = 0; i < AR8XXX_NUM_PHYS; i++) {
 		if (priv->chip->phy_fixup)
 			priv->chip->phy_fixup(priv, i);
@@ -1683,6 +1683,21 @@ ar8xxx_sw_set_flush_port_arl_table(struct switch_dev *dev,
 	return ret;
 }
 
+static int
+ar8xxx_phy_read(struct mii_bus *bus, int phy_addr, int reg_addr)
+{
+	struct ar8xxx_priv *priv = bus->priv;
+	return priv->chip->phy_read(priv, phy_addr, reg_addr);
+}
+
+static int
+ar8xxx_phy_write(struct mii_bus *bus, int phy_addr, int reg_addr,
+		 u16 reg_val)
+{
+	struct ar8xxx_priv *priv = bus->priv;
+	return priv->chip->phy_write(priv, phy_addr, reg_addr, reg_val);
+}
+
 static const struct switch_attr ar8xxx_sw_attr_globals[] = {
 	{
 		.type = SWITCH_TYPE_INT,
@@ -2471,6 +2486,7 @@ ar8xxx_mdiodev_probe(struct mdio_device *mdiodev)
 	const struct of_device_id *match;
 	struct ar8xxx_priv *priv;
 	struct switch_dev *swdev;
+	struct device_node *mdio_node;
 	int ret;
 
 	match = of_match_device(ar8xxx_mdiodev_of_match, &mdiodev->dev);
@@ -2493,6 +2509,21 @@ ar8xxx_mdiodev_probe(struct mdio_device *mdiodev)
 	if (ret)
 		goto free_priv;
 
+	if (priv->chip->phy_read && priv->chip->phy_write) {
+		priv->sw_mii_bus = devm_mdiobus_alloc(&mdiodev->dev);
+		priv->sw_mii_bus->name = "ar8xxx-mdio";
+		priv->sw_mii_bus->read = ar8xxx_phy_read;
+		priv->sw_mii_bus->write = ar8xxx_phy_write;
+		priv->sw_mii_bus->priv = priv;
+		priv->sw_mii_bus->parent = &mdiodev->dev;
+		snprintf(priv->sw_mii_bus->id, MII_BUS_ID_SIZE, "%s",
+			 dev_name(&mdiodev->dev));
+		mdio_node = of_get_child_by_name(priv->pdev->of_node, "mdio-bus");
+		ret = of_mdiobus_register(priv->sw_mii_bus, mdio_node);
+		if (ret)
+			goto free_priv;
+	}
+
 	swdev = &priv->dev;
 	swdev->alias = dev_name(&mdiodev->dev);
 	ret = register_switch(swdev, NULL);
@@ -2548,6 +2579,8 @@ ar8xxx_mdiodev_remove(struct mdio_device *mdiodev)
 
 	unregister_switch(&priv->dev);
 	ar8xxx_mib_stop(priv);
+	if(priv->sw_mii_bus)
+		mdiobus_unregister(priv->sw_mii_bus);
 	ar8xxx_free(priv);
 }
 

target/linux/generic/files/drivers/net/phy/ar8216.h

@@ -433,6 +433,8 @@ struct ar8xxx_chip {
 			      u32 *status, enum arl_op op);
 	int (*sw_hw_apply)(struct switch_dev *dev);
 	void (*phy_rgmii_set)(struct ar8xxx_priv *priv, struct phy_device *phydev);
+	int (*phy_read)(struct ar8xxx_priv *priv, int addr, int regnum);
+	int (*phy_write)(struct ar8xxx_priv *priv, int addr, int regnum, u16 val);
 
 	const struct ar8xxx_mib_desc *mib_decs;
 	unsigned num_mibs;
@@ -442,6 +444,7 @@ struct ar8xxx_chip {
 struct ar8xxx_priv {
 	struct switch_dev dev;
 	struct mii_bus *mii_bus;
+	struct mii_bus *sw_mii_bus;
 	struct phy_device *phy;
 	struct device *pdev;