[PATCHv3 1/5] net: dsa: Support internal phy on 'cpu' port

[Sebastian Reichel <sebastian.reichel@collabora.co.uk>]

This adds support for enabling the internal PHY for a 'cpu' port.
It has been tested on GE B850v3,  B650v3 and B450v3, which have a
built-in MV88E6240 switch connected to a PCIe based network card.
Without this patch the link does not come up and no traffic can be
routed through the switch.

The PHY interface, that is being used on the above test systems is
part of the MV88E6240 and since mv88e6xxx driver resets the chip
during probe, it is definitely disabled without this patch.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
---
 net/dsa/port.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/net/dsa/port.c b/net/dsa/port.c
index bb4be2679904..011ecd9b1be7 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -273,6 +273,55 @@ int dsa_port_vlan_del(struct dsa_port *dp,
 	return 0;
 }
 
+static int dsa_port_setup_phy_of(struct dsa_port *dp, bool enable)
+{
+	struct device_node *port_dn = dp->dn;
+	struct device_node *phy_dn;
+	struct dsa_switch *ds = dp->ds;
+	struct phy_device *phydev;
+	int port = dp->index;
+	int err = 0;
+
+	phy_dn = of_parse_phandle(port_dn, "phy-handle", 0);
+	if (!phy_dn)
+		return 0;
+
+	phydev = of_phy_find_device(phy_dn);
+	if (!phydev) {
+		err = -EPROBE_DEFER;
+		goto err_put_of;
+	}
+
+	if (enable) {
+		err = genphy_config_init(phydev);
+		if (err < 0)
+			goto err_put_dev;
+
+		err = genphy_resume(phydev);
+		if (err < 0)
+			goto err_put_dev;
+
+		err = genphy_read_status(phydev);
+		if (err < 0)
+			goto err_put_dev;
+	} else {
+		err = genphy_suspend(phydev);
+		if (err < 0)
+			goto err_put_dev;
+	}
+
+	if (ds->ops->adjust_link)
+		ds->ops->adjust_link(ds, port, phydev);
+
+	dev_dbg(ds->dev, "enabled port's phy: %s", phydev_name(phydev));
+
+err_put_dev:
+	put_device(&phydev->mdio.dev);
+err_put_of:
+	of_node_put(phy_dn);
+	return err;
+}
+
 int dsa_port_fixed_link_register_of(struct dsa_port *dp)
 {
 	struct device_node *dn = dp->dn;
@@ -305,6 +354,10 @@ int dsa_port_fixed_link_register_of(struct dsa_port *dp)
 			ds->ops->adjust_link(ds, port, phydev);
 
 		put_device(&phydev->mdio.dev);
+	} else {
+		err = dsa_port_setup_phy_of(dp, true);
+		if (err)
+			return err;
 	}
 
 	return 0;
@@ -316,4 +369,6 @@ void dsa_port_fixed_link_unregister_of(struct dsa_port *dp)
 
 	if (of_phy_is_fixed_link(dn))
 		of_phy_deregister_fixed_link(dn);
+	else
+		dsa_port_setup_phy_of(dp, false);
 }
-- 
2.15.1