ftgmac100: add IEEE 802.1Q VLAN support

The ftgmac100 NIC supports VLAN tag insertion and the MAC engine also
has a control to remove VLAN tags from received packets.

The VLAN control bits and VLAN tag information are contained in the
second word of the transmit and receive descriptors. The Insert VLAN
bit and the VLAN Tag available bit are only valid in the first segment
of the packet.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180530061711.23673-3-clg@kaod.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/net/ftgmac100.c

@@ -443,6 +443,22 @@ static void ftgmac100_do_tx(FTGMAC100State *s, uint32_t tx_ring,
             break;
         }
 
+        /* Check for VLAN */
+        if (bd.des0 & FTGMAC100_TXDES0_FTS &&
+            bd.des1 & FTGMAC100_TXDES1_INS_VLANTAG &&
+            be16_to_cpu(PKT_GET_ETH_HDR(ptr)->h_proto) != ETH_P_VLAN) {
+            if (frame_size + len + 4 > sizeof(s->frame)) {
+                qemu_log_mask(LOG_GUEST_ERROR, "%s: frame too big : %d bytes\n",
+                              __func__, len);
+                s->isr |= FTGMAC100_INT_XPKT_LOST;
+                len =  sizeof(s->frame) - frame_size - 4;
+            }
+            memmove(ptr + 16, ptr + 12, len - 12);
+            stw_be_p(ptr + 12, ETH_P_VLAN);
+            stw_be_p(ptr + 14, bd.des1);
+            len += 4;
+        }
+
         ptr += len;
         frame_size += len;
         if (bd.des0 & FTGMAC100_TXDES0_LTS) {
@@ -864,7 +880,20 @@ static ssize_t ftgmac100_receive(NetClientState *nc, const uint8_t *buf,
             buf_len += size - 4;
         }
         buf_addr = bd.des3;
-        dma_memory_write(&address_space_memory, buf_addr, buf, buf_len);
+        if (first && proto == ETH_P_VLAN && buf_len >= 18) {
+            bd.des1 = lduw_be_p(buf + 14) | FTGMAC100_RXDES1_VLANTAG_AVAIL;
+
+            if (s->maccr & FTGMAC100_MACCR_RM_VLAN) {
+                dma_memory_write(&address_space_memory, buf_addr, buf, 12);
+                dma_memory_write(&address_space_memory, buf_addr + 12, buf + 16,
+                                 buf_len - 16);
+            } else {
+                dma_memory_write(&address_space_memory, buf_addr, buf, buf_len);
+            }
+        } else {
+            bd.des1 = 0;
+            dma_memory_write(&address_space_memory, buf_addr, buf, buf_len);
+        }
         buf += buf_len;
         if (size < 4) {
             dma_memory_write(&address_space_memory, buf_addr + buf_len,