dsa: Support multiple MDIO busses

When using a cluster of switches, some topologies will have an MDIO
bus per switch, not one for the whole cluster. Allow this to be
represented in the device tree, by adding an optional mii-bus property
at the switch level. The old platform_device method of instantiation
supports this already, so only the device tree binding needs extending
with an additional optional phandle.

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

1 files changed, 11 insertions, 1 deletions

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index b445d492c115..78d4ac97aae3 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -574,7 +574,7 @@ static int dsa_of_probe(struct device *dev)
 {
         struct device_node *np = dev->of_node;
         struct device_node *child, *mdio, *ethernet, *port, *link;
-        struct mii_bus *mdio_bus;
+        struct mii_bus *mdio_bus, *mdio_bus_switch;
         struct net_device *ethernet_dev;
         struct dsa_platform_data *pd;
         struct dsa_chip_data *cd;
@@ -636,6 +636,16 @@ static int dsa_of_probe(struct device *dev)
                 if (!of_property_read_u32(child, "eeprom-length", &eeprom_len))
                         cd->eeprom_len = eeprom_len;
 
+                mdio = of_parse_phandle(child, "mii-bus", 0);
+                if (mdio) {
+                        mdio_bus_switch = of_mdio_find_bus(mdio);
+                        if (!mdio_bus_switch) {
+                                ret = -EPROBE_DEFER;
+                                goto out_free_chip;
+                        }
+                        cd->host_dev = &mdio_bus_switch->dev;
+                }
+
                 for_each_available_child_of_node(child, port) {
                         port_reg = of_get_property(port, "reg", NULL);
                         if (!port_reg)