[PATCH net-next] net: dsa: Allow compiling out legacy support

[Florian Fainelli <f.fainelli@gmail.com>]

Introduce a configuration option: CONFIG_NET_DSA_LEGACY allowing to compile out
support for the old platform device and Device Tree binding registration.
Support for these configurations is scheduled to be removed in 4.17.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 include/net/dsa.h  |  9 +++++++++
 net/dsa/Kconfig    |  8 ++++++++
 net/dsa/Makefile   |  3 ++-
 net/dsa/dsa_priv.h | 23 +++++++++++++++++++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 2a05738570d8..3e61bcada6ea 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -472,11 +472,20 @@ struct dsa_switch_driver {
 	const struct dsa_switch_ops *ops;
 };
 
+#if IS_ENABLED(CONFIG_NET_DSA_LEGACY)
 /* 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);
 
+#else
+static inline void register_switch_driver(struct dsa_switch_driver *type) { }
+static inline void unregister_switch_driver(struct dsa_switch_driver *type) { }
+static inline struct mii_bus *dsa_host_dev_to_mii_bus(struct device *dev)
+{
+	return NULL;
+}
+#endif
 struct net_device *dsa_dev_to_net_device(struct device *dev);
 
 /* Keep inline for faster access in hot path */
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 03c3bdf25468..b6ec8e9069e4 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -16,6 +16,14 @@ config NET_DSA
 
 if NET_DSA
 
+config NET_DSA_LEGACY
+	bool "Support for older platform device and Device Tree registration"
+	---help---
+	  Say Y if you want to enable support for the older platform device and
+	  deprectaed Device Tree binding registration.
+
+	  This feature is scheduled for removal in 4.17.
+
 # tagging formats
 config NET_DSA_TAG_BRCM
 	bool
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 0e13c1f95d13..9e4d3536f977 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -1,7 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 # the core
 obj-$(CONFIG_NET_DSA) += dsa_core.o
-dsa_core-y += dsa.o dsa2.o legacy.o master.o port.o slave.o switch.o
+dsa_core-y += dsa.o dsa2.o master.o port.o slave.o switch.o
+dsa_core-$(CONFIG_NET_DSA_LEGACY) += legacy.o
 
 # tagging formats
 dsa_core-$(CONFIG_NET_DSA_TAG_BRCM) += tag_brcm.o
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 7d036696e8c4..44d2f25736a0 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -97,6 +97,7 @@ const struct dsa_device_ops *dsa_resolve_tag_protocol(int tag_protocol);
 bool dsa_schedule_work(struct work_struct *work);
 
 /* legacy.c */
+#if IS_ENABLED(CONFIG_NET_DSA_LEGACY)
 int dsa_legacy_register(void);
 void dsa_legacy_unregister(void);
 int dsa_legacy_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
@@ -106,6 +107,28 @@ int dsa_legacy_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
 int dsa_legacy_fdb_del(struct ndmsg *ndm, struct nlattr *tb[],
 		       struct net_device *dev,
 		       const unsigned char *addr, u16 vid);
+#else
+static inline int dsa_legacy_register(void)
+{
+	return -ENODEV;
+}
+
+static inline void dsa_legacy_unregister(void) { }
+static inline int dsa_legacy_fdb_add(struct ndmsg *ndm, struct nlattr *tb[],
+				     struct net_device *dev,
+				     const unsigned char *addr, u16 vid,
+				     u16 flags)
+{
+	return 0;
+}
+
+static inline int dsa_legacy_fdb_del(struct ndmsg *ndm, struct nlattr *tb[],
+				     struct net_device *dev,
+				     const unsigned char *addr, u16 vid)
+{
+	return 0;
+}
+#endif
 
 /* master.c */
 int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp);
-- 
2.14.1