net: dsa: isolate legacy code

This patch moves as is the legacy DSA code from dsa.c to legacy.c,
except the few shared symbols which remain in dsa.c.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -302,7 +302,7 @@ struct dsa_notifier_bridge_info {
 
 struct dsa_switch_ops {
 	/*
-	 * Probing and setup.
+	 * Legacy probing.
 	 */
 	const char	*(*probe)(struct device *dsa_dev,
 				  struct device *host_dev, int sw_addr,
@@ -472,9 +472,11 @@ struct dsa_switch_driver {
 	const struct dsa_switch_ops *ops;
 };
 
+/* Legacy driver registration */
 void register_switch_driver(struct dsa_switch_driver *type);
 void unregister_switch_driver(struct dsa_switch_driver *type);
 struct mii_bus *dsa_host_dev_to_mii_bus(struct device *dev);
+
 struct net_device *dsa_dev_to_net_device(struct device *dev);
 
 static inline bool dsa_uses_tagged_protocol(struct dsa_switch_tree *dst)

net/dsa/Makefile

 # the core
 obj-$(CONFIG_NET_DSA) += dsa_core.o
-dsa_core-y += dsa.o slave.o dsa2.o switch.o
+dsa_core-y += dsa.o slave.o dsa2.o switch.o legacy.o
 
 # tagging formats
 dsa_core-$(CONFIG_NET_DSA_TAG_BRCM) += tag_brcm.o

net/dsa/dsa_priv.h

@@ -55,6 +55,10 @@ const struct dsa_device_ops *dsa_resolve_tag_protocol(int tag_protocol);
 int dsa_cpu_port_ethtool_setup(struct dsa_switch *ds);
 void dsa_cpu_port_ethtool_restore(struct dsa_switch *ds);
 
+/* legacy.c */
+int dsa_legacy_register(void);
+void dsa_legacy_unregister(void);
+
 /* slave.c */
 extern const struct dsa_device_ops notag_netdev_ops;
 void dsa_slave_mii_bus_init(struct dsa_switch *ds);