mdio_bus: Port of_mdio_find_bus() from Linux kernel

Port of_mdio_find_bus() from Linux kernel. This function is used in
MDIO multiplexor infrastructure added in following commit.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 012b90e834..6ae85692da 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -207,6 +207,33 @@ struct mii_bus *mdiobus_get_bus(int busnum)
 }
 
 /**
+ * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
+ * @mdio_bus_np: Pointer to the mii_bus.
+ *
+ * Returns a reference to the mii_bus, or NULL if none found.
+ *
+ * Because the association of a device_node and mii_bus is made via
+ * mdiobus_register(), the mii_bus cannot be found before it is
+ * registered with mdiobus_register().
+ *
+ */
+struct mii_bus *of_mdio_find_bus(struct device_node *mdio_bus_np)
+{
+	struct mii_bus *mii;
+
+	if (!mdio_bus_np)
+		return NULL;
+
+	for_each_mii_bus(mii)
+		if (mii->dev.device_node == mdio_bus_np)
+			return mii;
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_mdio_find_bus);
+
+
+/**
  * mdio_bus_match - determine if given PHY driver supports the given PHY device
  * @dev: target PHY device
  * @drv: given PHY driver