net: xilinx: axienet: Support IFF_ALLMULTI

Add support for IFF_ALLMULTI by configuring a single filter to match the
multicast address bit. This allows us to keep promiscuous mode disabled,
even when we have more than four multicast addresses. An even better
solution would be to "pack" addresses into the available CAM registers,
but that can wait for a future series.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240822154059.1066595-6-sean.anderson@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -175,6 +175,8 @@
 #define XAE_FFE_OFFSET		0x0000070C /* Frame Filter Enable */
 #define XAE_AF0_OFFSET		0x00000710 /* Address Filter 0 */
 #define XAE_AF1_OFFSET		0x00000714 /* Address Filter 1 */
+#define XAE_AM0_OFFSET		0x00000750 /* Frame Filter Mask Value Bytes 3-0 */
+#define XAE_AM1_OFFSET		0x00000754 /* Frame Filter Mask Value Bytes 7-4 */
 
 #define XAE_TX_VLAN_DATA_OFFSET 0x00004000 /* TX VLAN data table address */
 #define XAE_RX_VLAN_DATA_OFFSET 0x00008000 /* RX VLAN data table address */

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -437,18 +437,27 @@ static void axienet_set_multicast_list(struct net_device *ndev)
 	u32 reg, af0reg, af1reg;
 	struct axienet_local *lp = netdev_priv(ndev);
 
-	if (ndev->flags & (IFF_ALLMULTI | IFF_PROMISC) ||
-	    netdev_mc_count(ndev) > XAE_MULTICAST_CAM_TABLE_NUM) {
-		reg = axienet_ior(lp, XAE_FMI_OFFSET);
+	reg = axienet_ior(lp, XAE_FMI_OFFSET);
+	reg &= ~XAE_FMI_PM_MASK;
+	if (ndev->flags & IFF_PROMISC)
 		reg |= XAE_FMI_PM_MASK;
+	else
+		reg &= ~XAE_FMI_PM_MASK;
+	axienet_iow(lp, XAE_FMI_OFFSET, reg);
+
+	if (ndev->flags & IFF_ALLMULTI ||
+	    netdev_mc_count(ndev) > XAE_MULTICAST_CAM_TABLE_NUM) {
+		reg &= 0xFFFFFF00;
 		axienet_iow(lp, XAE_FMI_OFFSET, reg);
+		axienet_iow(lp, XAE_AF0_OFFSET, 1); /* Multicast bit */
+		axienet_iow(lp, XAE_AF1_OFFSET, 0);
+		axienet_iow(lp, XAE_AM0_OFFSET, 1); /* ditto */
+		axienet_iow(lp, XAE_AM1_OFFSET, 0);
+		axienet_iow(lp, XAE_FFE_OFFSET, 1);
+		i = 1;
 	} else if (!netdev_mc_empty(ndev)) {
 		struct netdev_hw_addr *ha;
 
-		reg = axienet_ior(lp, XAE_FMI_OFFSET);
-		reg &= ~XAE_FMI_PM_MASK;
-		axienet_iow(lp, XAE_FMI_OFFSET, reg);
-
 		netdev_for_each_mc_addr(ha, ndev) {
 			if (i >= XAE_MULTICAST_CAM_TABLE_NUM)
 				break;
@@ -461,24 +470,21 @@ static void axienet_set_multicast_list(struct net_device *ndev)
 			af1reg = (ha->addr[4]);
 			af1reg |= (ha->addr[5] << 8);
 
-			reg = axienet_ior(lp, XAE_FMI_OFFSET) & 0xFFFFFF00;
+			reg &= 0xFFFFFF00;
 			reg |= i;
 
 			axienet_iow(lp, XAE_FMI_OFFSET, reg);
 			axienet_iow(lp, XAE_AF0_OFFSET, af0reg);
 			axienet_iow(lp, XAE_AF1_OFFSET, af1reg);
+			axienet_iow(lp, XAE_AM0_OFFSET, 0xffffffff);
+			axienet_iow(lp, XAE_AM1_OFFSET, 0x0000ffff);
 			axienet_iow(lp, XAE_FFE_OFFSET, 1);
 			i++;
 		}
-	} else {
-		reg = axienet_ior(lp, XAE_FMI_OFFSET);
-		reg &= ~XAE_FMI_PM_MASK;
-
-		axienet_iow(lp, XAE_FMI_OFFSET, reg);
 	}
 
 	for (; i < XAE_MULTICAST_CAM_TABLE_NUM; i++) {
-		reg = axienet_ior(lp, XAE_FMI_OFFSET) & 0xFFFFFF00;
+		reg &= 0xFFFFFF00;
 		reg |= i;
 		axienet_iow(lp, XAE_FMI_OFFSET, reg);
 		axienet_iow(lp, XAE_FFE_OFFSET, 0);