net: phy: add device-managed devm_mdiobus_register

If there's no special ordering requirement for mdiobus_unregister(),
then driver code can be simplified by using a device-managed version
of mdiobus_register(). Prerequisite is that bus allocation has been
done device-managed too. Else mdiobus_free() may be called whilst
bus is still registered, resulting in a BUG_ON(). Therefore let
devm_mdiobus_register() return -EPERM if bus was allocated
non-managed.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 0 deletions

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 2432ca463ddc..3941a6bcba10 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -241,6 +241,9 @@ struct mii_bus {
 	int (*reset)(struct mii_bus *bus);
 	struct mdio_bus_stats stats[PHY_MAX_ADDR];
 
+	unsigned int is_managed:1;	/* is device-managed */
+	unsigned int is_managed_registered:1;
+
 	/*
 	 * A lock to ensure that only one thing can read/write
 	 * the MDIO bus at a time
@@ -286,6 +289,20 @@ static inline struct mii_bus *mdiobus_alloc(void)
 
 int __mdiobus_register(struct mii_bus *bus, struct module *owner);
 #define mdiobus_register(bus) __mdiobus_register(bus, THIS_MODULE)
+static inline int devm_mdiobus_register(struct mii_bus *bus)
+{
+	int ret;
+
+	if (!bus->is_managed)
+		return -EPERM;
+
+	ret = mdiobus_register(bus);
+	if (!ret)
+		bus->is_managed_registered = 1;
+
+	return ret;
+}
+
 void mdiobus_unregister(struct mii_bus *bus);
 void mdiobus_free(struct mii_bus *bus);
 struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv);