net: pcs: xpcs: add xpcs_create_mdiodev()

Add xpcs_create_mdiodev() to simplify the creation of the mdio device
associated with the XPCS. In order to allow xpcs_destroy() to clean
this up, we need to arrange for xpcs_create() to take a refcount on
the mdiodev, and xpcs_destroy() to put it.

Adding the refcounting to xpcs_create()..xpcs_destroy() will be
transparent to existing users of these interfaces.
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/pcs/pcs-xpcs.c

@@ -1235,6 +1235,7 @@ struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev,
 	if (!xpcs)
 		return ERR_PTR(-ENOMEM);
 
+	mdio_device_get(mdiodev);
 	xpcs->mdiodev = mdiodev;
 
 	xpcs_id = xpcs_get_id(xpcs);
@@ -1267,6 +1268,7 @@ struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev,
 	ret = -ENODEV;
 
 out:
+	mdio_device_put(mdiodev);
 	kfree(xpcs);
 
 	return ERR_PTR(ret);
@@ -1275,8 +1277,34 @@ EXPORT_SYMBOL_GPL(xpcs_create);
 
 void xpcs_destroy(struct dw_xpcs *xpcs)
 {
+	if (xpcs)
+		mdio_device_put(xpcs->mdiodev);
 	kfree(xpcs);
 }
 EXPORT_SYMBOL_GPL(xpcs_destroy);
 
+struct dw_xpcs *xpcs_create_mdiodev(struct mii_bus *bus, int addr,
+				    phy_interface_t interface)
+{
+	struct mdio_device *mdiodev;
+	struct dw_xpcs *xpcs;
+
+	mdiodev = mdio_device_create(bus, addr);
+	if (IS_ERR(mdiodev))
+		return ERR_CAST(mdiodev);
+
+	xpcs = xpcs_create(mdiodev, interface);
+
+	/* xpcs_create() has taken a refcount on the mdiodev if it was
+	 * successful. If xpcs_create() fails, this will free the mdio
+	 * device here. In any case, we don't need to hold our reference
+	 * anymore, and putting it here will allow mdio_device_put() in
+	 * xpcs_destroy() to automatically free the mdio device.
+	 */
+	mdio_device_put(mdiodev);
+
+	return xpcs;
+}
+EXPORT_SYMBOL_GPL(xpcs_create_mdiodev);
+
 MODULE_LICENSE("GPL v2");

include/linux/pcs/pcs-xpcs.h

@@ -37,6 +37,8 @@ int xpcs_config_eee(struct dw_xpcs *xpcs, int mult_fact_100ns,
 		    int enable);
 struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev,
 			    phy_interface_t interface);
+struct dw_xpcs *xpcs_create_mdiodev(struct mii_bus *bus, int addr,
+				    phy_interface_t interface);
 void xpcs_destroy(struct dw_xpcs *xpcs);
 
 #endif /* __LINUX_PCS_XPCS_H */