net: lan966x: Implement the callback SWITCHDEV_ATTR_ID_BRIDGE_MC_DISABLED

The callback allows to enable/disable multicast snooping.
When the snooping is enabled, all IGMP and MLD frames are redirected to
the CPU, therefore make sure not to set the skb flag 'offload_fwd_mark'.
The HW will not flood multicast ipv4/ipv6 data frames.
When the snooping is disabled, the HW will flood IGMP, MLD and multicast
ipv4/ipv6 frames according to the mcast_flood flag.
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/microchip/lan966x/lan966x_main.c

@@ -4,11 +4,13 @@
 #include <linux/if_bridge.h>
 #include <linux/if_vlan.h>
 #include <linux/iopoll.h>
+#include <linux/ip.h>
 #include <linux/of_platform.h>
 #include <linux/of_net.h>
 #include <linux/packing.h>
 #include <linux/phy/phy.h>
 #include <linux/reset.h>
+#include <net/addrconf.h>
 
 #include "lan966x_main.h"
 
@@ -419,6 +421,32 @@ bool lan966x_netdevice_check(const struct net_device *dev)
 	return dev->netdev_ops == &lan966x_port_netdev_ops;
 }
 
+static bool lan966x_hw_offload(struct lan966x *lan966x, u32 port,
+			       struct sk_buff *skb)
+{
+	u32 val;
+
+	/* The IGMP and MLD frames are not forward by the HW if
+	 * multicast snooping is enabled, therefor don't mark as
+	 * offload to allow the SW to forward the frames accordingly.
+	 */
+	val = lan_rd(lan966x, ANA_CPU_FWD_CFG(port));
+	if (!(val & (ANA_CPU_FWD_CFG_IGMP_REDIR_ENA |
+		     ANA_CPU_FWD_CFG_MLD_REDIR_ENA)))
+		return true;
+
+	if (skb->protocol == htons(ETH_P_IP) &&
+	    ip_hdr(skb)->protocol == IPPROTO_IGMP)
+		return false;
+
+	if (skb->protocol == htons(ETH_P_IPV6) &&
+	    ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) &&
+	    !ipv6_mc_check_mld(skb))
+		return false;
+
+	return true;
+}
+
 static int lan966x_port_xtr_status(struct lan966x *lan966x, u8 grp)
 {
 	return lan_rd(lan966x, QS_XTR_RD(grp));
@@ -563,9 +591,14 @@ static irqreturn_t lan966x_xtr_irq_handler(int irq, void *args)
 		lan966x_ptp_rxtstamp(lan966x, skb, timestamp);
 		skb->protocol = eth_type_trans(skb, dev);
 
-		if (lan966x->bridge_mask & BIT(src_port))
+		if (lan966x->bridge_mask & BIT(src_port)) {
 			skb->offload_fwd_mark = 1;
 
+			skb_reset_network_header(skb);
+			if (!lan966x_hw_offload(lan966x, src_port, skb))
+				skb->offload_fwd_mark = 0;
+		}
+
 		netif_rx_ni(skb);
 		dev->stats.rx_bytes += len;
 		dev->stats.rx_packets++;

drivers/net/ethernet/microchip/lan966x/lan966x_main.h

@@ -170,6 +170,7 @@ struct lan966x_port {
 	bool vlan_aware;
 
 	bool learn_ena;
+	bool mcast_ena;
 
 	struct phylink_config phylink_config;
 	struct phylink_pcs phylink_pcs;

drivers/net/ethernet/microchip/lan966x/lan966x_regs.h

@@ -299,6 +299,24 @@ enum lan966x_target {
 /*      ANA:PORT:CPU_FWD_CFG */
 #define ANA_CPU_FWD_CFG(g)        __REG(TARGET_ANA, 0, 1, 28672, g, 9, 128, 96, 0, 1, 4)
 
+#define ANA_CPU_FWD_CFG_MLD_REDIR_ENA            BIT(6)
+#define ANA_CPU_FWD_CFG_MLD_REDIR_ENA_SET(x)\
+	FIELD_PREP(ANA_CPU_FWD_CFG_MLD_REDIR_ENA, x)
+#define ANA_CPU_FWD_CFG_MLD_REDIR_ENA_GET(x)\
+	FIELD_GET(ANA_CPU_FWD_CFG_MLD_REDIR_ENA, x)
+
+#define ANA_CPU_FWD_CFG_IGMP_REDIR_ENA           BIT(5)
+#define ANA_CPU_FWD_CFG_IGMP_REDIR_ENA_SET(x)\
+	FIELD_PREP(ANA_CPU_FWD_CFG_IGMP_REDIR_ENA, x)
+#define ANA_CPU_FWD_CFG_IGMP_REDIR_ENA_GET(x)\
+	FIELD_GET(ANA_CPU_FWD_CFG_IGMP_REDIR_ENA, x)
+
+#define ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA       BIT(4)
+#define ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA_SET(x)\
+	FIELD_PREP(ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA, x)
+#define ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA_GET(x)\
+	FIELD_GET(ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA, x)
+
 #define ANA_CPU_FWD_CFG_SRC_COPY_ENA             BIT(3)
 #define ANA_CPU_FWD_CFG_SRC_COPY_ENA_SET(x)\
 	FIELD_PREP(ANA_CPU_FWD_CFG_SRC_COPY_ENA, x)

drivers/net/ethernet/microchip/lan966x/lan966x_switchdev.c

@@ -9,6 +9,37 @@ static struct notifier_block lan966x_netdevice_nb __read_mostly;
 static struct notifier_block lan966x_switchdev_nb __read_mostly;
 static struct notifier_block lan966x_switchdev_blocking_nb __read_mostly;
 
+static void lan966x_port_set_mcast_ip_flood(struct lan966x_port *port,
+					    u32 pgid_ip)
+{
+	struct lan966x *lan966x = port->lan966x;
+	u32 flood_mask_ip;
+
+	flood_mask_ip = lan_rd(lan966x, ANA_PGID(pgid_ip));
+	flood_mask_ip = ANA_PGID_PGID_GET(flood_mask_ip);
+
+	/* If mcast snooping is not enabled then use mcast flood mask
+	 * to decide to enable multicast flooding or not.
+	 */
+	if (!port->mcast_ena) {
+		u32 flood_mask;
+
+		flood_mask = lan_rd(lan966x, ANA_PGID(PGID_MC));
+		flood_mask = ANA_PGID_PGID_GET(flood_mask);
+
+		if (flood_mask & BIT(port->chip_port))
+			flood_mask_ip |= BIT(port->chip_port);
+		else
+			flood_mask_ip &= ~BIT(port->chip_port);
+	} else {
+		flood_mask_ip &= ~BIT(port->chip_port);
+	}
+
+	lan_rmw(ANA_PGID_PGID_SET(flood_mask_ip),
+		ANA_PGID_PGID,
+		lan966x, ANA_PGID(pgid_ip));
+}
+
 static void lan966x_port_set_mcast_flood(struct lan966x_port *port,
 					 bool enabled)
 {
@@ -23,6 +54,11 @@ static void lan966x_port_set_mcast_flood(struct lan966x_port *port,
 	lan_rmw(ANA_PGID_PGID_SET(val),
 		ANA_PGID_PGID,
 		port->lan966x, ANA_PGID(PGID_MC));
+
+	if (!port->mcast_ena) {
+		lan966x_port_set_mcast_ip_flood(port, PGID_MCIPV4);
+		lan966x_port_set_mcast_ip_flood(port, PGID_MCIPV6);
+	}
 }
 
 static void lan966x_port_set_ucast_flood(struct lan966x_port *port,
@@ -144,6 +180,24 @@ static void lan966x_port_ageing_set(struct lan966x_port *port,
 	lan966x_mac_set_ageing(port->lan966x, ageing_time);
 }
 
+static void lan966x_port_mc_set(struct lan966x_port *port, bool mcast_ena)
+{
+	struct lan966x *lan966x = port->lan966x;
+
+	port->mcast_ena = mcast_ena;
+
+	lan_rmw(ANA_CPU_FWD_CFG_IGMP_REDIR_ENA_SET(mcast_ena) |
+		ANA_CPU_FWD_CFG_MLD_REDIR_ENA_SET(mcast_ena) |
+		ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA_SET(mcast_ena),
+		ANA_CPU_FWD_CFG_IGMP_REDIR_ENA |
+		ANA_CPU_FWD_CFG_MLD_REDIR_ENA |
+		ANA_CPU_FWD_CFG_IPMC_CTRL_COPY_ENA,
+		lan966x, ANA_CPU_FWD_CFG(port->chip_port));
+
+	lan966x_port_set_mcast_ip_flood(port, PGID_MCIPV4);
+	lan966x_port_set_mcast_ip_flood(port, PGID_MCIPV6);
+}
+
 static int lan966x_port_attr_set(struct net_device *dev, const void *ctx,
 				 const struct switchdev_attr *attr,
 				 struct netlink_ext_ack *extack)
@@ -171,6 +225,9 @@ static int lan966x_port_attr_set(struct net_device *dev, const void *ctx,
 		lan966x_vlan_port_set_vlan_aware(port, attr->u.vlan_filtering);
 		lan966x_vlan_port_apply(port);
 		break;
+	case SWITCHDEV_ATTR_ID_BRIDGE_MC_DISABLED:
+		lan966x_port_mc_set(port, !attr->u.mc_disabled);
+		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;