net: dsa: Provide a slave MII bus if needed

Mimic what net/dsa/dsa.c does and provide a slave MII bus by default
which will be created if the driver implements a phy_read method.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 921a36fd139d..4e0f3c268103 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -312,6 +312,18 @@ static int dsa_ds_apply(struct dsa_switch_tree *dst, struct dsa_switch *ds)
         if (err < 0)
                 return err;
 
+        if (!ds->slave_mii_bus && ds->drv->phy_read) {
+                ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
+                if (!ds->slave_mii_bus)
+                        return -ENOMEM;
+
+                dsa_slave_mii_bus_init(ds);
+
+                err = mdiobus_register(ds->slave_mii_bus);
+                if (err < 0)
+                        return err;
+        }
+
         for (index = 0; index < DSA_MAX_PORTS; index++) {
                 port = ds->ports[index].dn;
                 if (!port)
@@ -361,6 +373,9 @@ static void dsa_ds_unapply(struct dsa_switch_tree *dst, struct dsa_switch *ds)
 
                 dsa_user_port_unapply(port, index, ds);
         }
+
+        if (ds->slave_mii_bus && ds->drv->phy_read)
+                mdiobus_unregister(ds->slave_mii_bus);
 }
 
 static int dsa_dst_apply(struct dsa_switch_tree *dst)