amt: add control plane of amt interface

It adds definitions and control plane code for AMT.
this is very similar to udp tunneling interfaces such as gtp, vxlan, etc.
In the next patch, data plane code will be added.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -1020,6 +1020,14 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/light/ams,as73211.yaml
 F:	drivers/iio/light/as73211.c
 
+AMT (Automatic Multicast Tunneling)
+M:	Taehee Yoo <ap420073@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
+F:	drivers/net/amt.c
+
 ANALOG DEVICES INC AD7192 DRIVER
 M:	Alexandru Tachici <alexandru.tachici@analog.com>
 L:	linux-iio@vger.kernel.org

drivers/net/Kconfig

@@ -291,6 +291,22 @@ config GTP
 	  To compile this drivers as a module, choose M here: the module
 	  will be called gtp.
 
+config AMT
+	tristate "Automatic Multicast Tunneling (AMT)"
+	depends on INET && IP_MULTICAST
+	select NET_UDP_TUNNEL
+	help
+	  This allows one to create AMT(Automatic Multicast Tunneling)
+	  virtual interfaces that provide multicast tunneling.
+	  There are two roles, Gateway, and Relay.
+	  Gateway Encapsulates IGMP/MLD traffic from listeners to the Relay.
+	  Gateway Decapsulates multicast traffic from the Relay to Listeners.
+	  Relay Encapsulates multicast traffic from Sources to Gateway.
+	  Relay Decapsulates IGMP/MLD traffic from Gateway.
+
+	  To compile this drivers as a module, choose M here: the module
+	  will be called amt.
+
 config MACSEC
 	tristate "IEEE 802.1AE MAC-level encryption (MACsec)"
 	select CRYPTO

drivers/net/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_WIREGUARD) += wireguard/
 obj-$(CONFIG_EQUALIZER) += eql.o
 obj-$(CONFIG_IFB) += ifb.o
 obj-$(CONFIG_MACSEC) += macsec.o
+obj-$(CONFIG_AMT) += amt.o
 obj-$(CONFIG_MACVLAN) += macvlan.o
 obj-$(CONFIG_MACVTAP) += macvtap.o
 obj-$(CONFIG_MII) += mii.o