Added MDNS and driver support for multicast

src/drivers/tm4c.c

@@ -160,7 +160,7 @@ static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
   // EMAC->EMACDMABUSMOD = MG_BIT(13) | MG_BIT(16) | MG_BIT(22) | MG_BIT(23) | MG_BIT(25);
   EMAC->EMACIM = MG_BIT(3) | MG_BIT(9);  // Mask timestamp & PMT IT
   EMAC->EMACFLOWCTL = MG_BIT(7);      // Disable zero-quanta pause
-  // EMAC->EMACFRAMEFLTR = MG_BIT(31);   // Receive all
+  EMAC->EMACFRAMEFLTR = MG_BIT(10);   // Perfect filtering
   // EMAC->EMACPC defaults to internal PHY (EPHY) in MMI mode
   emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(15));  // Reset internal PHY (EPHY)
   emac_write_phy(EPHY_ADDR, EPHYBMCR, MG_BIT(12));  // Set autonegotiation
@@ -174,8 +174,14 @@ static bool mg_tcpip_driver_tm4c_init(struct mg_tcpip_if *ifp) {
   EMAC->EMACADDR0L = (uint32_t) (ifp->mac[3] << 24) |
                      ((uint32_t) ifp->mac[2] << 16) |
                      ((uint32_t) ifp->mac[1] << 8) | ifp->mac[0];
-  // NOTE(scaprile) There are 3 additional slots for filtering, disabled by
-  // default. This also applies to the STM32 driver (at least for F7)
+#if MG_TCPIP_MCAST
+  // add mDNS / DNS-SD multicast address
+  EMAC->EMACADDR1L = (uint32_t) mcast_addr[3] << 24 |
+                     (uint32_t) mcast_addr[2] << 16 |
+                     (uint32_t) mcast_addr[1] << 8 | (uint32_t) mcast_addr[0];
+  EMAC->EMACADDR1H = (uint32_t) mcast_addr[5] << 8 | (uint32_t) mcast_addr[4];
+  EMAC->EMACADDR1H |= MG_BIT(31);  // AE
+#endif
   return true;
 }