mdio_bus: implement devm_mdiobus_alloc/devm_mdiobus_free

Add a resource managed devm_mdiobus_alloc[_size]()/devm_mdiobus_free()
to automatically clean up MDIO bus alocations made by MDIO drivers,
thus leading to simplified MDIO drivers code.

Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-and-tested-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/driver-model/devres.txt

@@ -308,3 +308,8 @@ SLAVE DMA ENGINE
 
 SPI
   devm_spi_register_master()
+
+MDIO
+  devm_mdiobus_alloc()
+  devm_mdiobus_alloc_size()
+  devm_mdiobus_free()

drivers/net/phy/mdio_bus.c

@@ -69,6 +69,73 @@ struct mii_bus *mdiobus_alloc_size(size_t size)
 }
 EXPORT_SYMBOL(mdiobus_alloc_size);
 
+static void _devm_mdiobus_free(struct device *dev, void *res)
+{
+	mdiobus_free(*(struct mii_bus **)res);
+}
+
+static int devm_mdiobus_match(struct device *dev, void *res, void *data)
+{
+	struct mii_bus **r = res;
+
+	if (WARN_ON(!r || !*r))
+		return 0;
+
+	return *r == data;
+}
+
+/**
+ * devm_mdiobus_alloc_size - Resource-managed mdiobus_alloc_size()
+ * @dev:		Device to allocate mii_bus for
+ * @sizeof_priv:	Space to allocate for private structure.
+ *
+ * Managed mdiobus_alloc_size. mii_bus allocated with this function is
+ * automatically freed on driver detach.
+ *
+ * If an mii_bus allocated with this function needs to be freed separately,
+ * devm_mdiobus_free() must be used.
+ *
+ * RETURNS:
+ * Pointer to allocated mii_bus on success, NULL on failure.
+ */
+struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv)
+{
+	struct mii_bus **ptr, *bus;
+
+	ptr = devres_alloc(_devm_mdiobus_free, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	/* use raw alloc_dr for kmalloc caller tracing */
+	bus = mdiobus_alloc_size(sizeof_priv);
+	if (bus) {
+		*ptr = bus;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return bus;
+}
+EXPORT_SYMBOL_GPL(devm_mdiobus_alloc);
+
+/**
+ * devm_mdiobus_free - Resource-managed mdiobus_free()
+ * @dev:		Device this mii_bus belongs to
+ * @bus:		the mii_bus associated with the device
+ *
+ * Free mii_bus allocated with devm_mdiobus_alloc_size().
+ */
+void devm_mdiobus_free(struct device *dev, struct mii_bus *bus)
+{
+	int rc;
+
+	rc = devres_release(dev, _devm_mdiobus_free,
+			    devm_mdiobus_match, bus);
+	WARN_ON(rc);
+}
+EXPORT_SYMBOL_GPL(devm_mdiobus_free);
+
 /**
  * mdiobus_release - mii_bus device release callback
  * @d: the target struct device that contains the mii_bus

include/linux/phy.h

@@ -198,6 +198,13 @@ static inline struct mii_bus *mdiobus_alloc(void)
 int mdiobus_register(struct mii_bus *bus);
 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);
+static inline struct mii_bus *devm_mdiobus_alloc(struct device *dev)
+{
+	return devm_mdiobus_alloc_size(dev, 0);
+}
+
+void devm_mdiobus_free(struct device *dev, struct mii_bus *bus);
 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr);
 int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum);
 int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val);