net: Introduce net_if_carrier_down

This introduces net_if_carrier_down so the L2 driver can inform when it
has lost connectivity so all packets shall be flushed and the interface
should be put down.

Fixes #5317

Signed-off-by: Luiz Augusto von Dentz <[email protected]>

Author: Vudentz

subsys/net/ip/net_if.c

@@ -1876,6 +1876,17 @@ int net_if_up(struct net_if *iface)
 	return 0;
 }
 
+void net_if_carrier_down(struct net_if *iface)
+{
+	NET_DBG("iface %p", iface);
+
+	atomic_clear_bit(iface->flags, NET_IF_UP);
+
+	net_if_flush_tx(iface);
+
+	net_mgmt_event_notify(NET_EVENT_IF_DOWN, iface);
+}
+
 int net_if_down(struct net_if *iface)
 {
 	int status;

subsys/net/ip/net_private.h

@@ -18,6 +18,7 @@
 extern void net_pkt_init(void);
 extern void net_if_init(struct k_sem *startup_sync);
 extern void net_if_post_init(void);
+extern void net_if_carrier_down(struct net_if *iface);
 extern void net_context_init(void);
 enum net_verdict net_ipv4_process_pkt(struct net_pkt *pkt);
 enum net_verdict net_ipv6_process_pkt(struct net_pkt *pkt);