[PATCH net v5 4/6] net: dsa: mt7530: fix handling of LLDP frames

[arinc9.unal@gmail.com]

From: Arınç ÜNAL <arinc.unal@arinc9.com>

LLDP frames are link-local frames, therefore they must be trapped to the
CPU port. Currently, the MT753X switches treat LLDP frames as regular
multicast frames, therefore flooding them to user ports. To fix this, set
LLDP frames to be trapped to the CPU port(s).

Fixes: b8f126a8d543 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
---
 drivers/net/dsa/mt7530.c | 8 ++++++++
 drivers/net/dsa/mt7530.h | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 7b72cf3a0e30..c85876fd9107 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2266,6 +2266,10 @@ mt7530_setup(struct dsa_switch *ds)
 	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
 		   MT753X_BPDU_CPU_ONLY);
 
+	/* Trap LLDP frames with :0E MAC DA to the CPU port */
+	mt7530_rmw(priv, MT753X_RGAC2, MT753X_R0E_PORT_FW_MASK,
+		   MT753X_R0E_PORT_FW(MT753X_BPDU_CPU_ONLY));
+
 	/* Enable and reset MIB counters */
 	mt7530_mib_reset(ds);
 
@@ -2369,6 +2373,10 @@ mt7531_setup_common(struct dsa_switch *ds)
 	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
 		   MT753X_BPDU_CPU_ONLY);
 
+	/* Trap LLDP frames with :0E MAC DA to the CPU port(s) */
+	mt7530_rmw(priv, MT753X_RGAC2, MT753X_R0E_PORT_FW_MASK,
+		   MT753X_R0E_PORT_FW(MT753X_BPDU_CPU_ONLY));
+
 	/* Enable and reset MIB counters */
 	mt7530_mib_reset(ds);
 
diff --git a/drivers/net/dsa/mt7530.h b/drivers/net/dsa/mt7530.h
index e590cf43f3ae..08045b035e6a 100644
--- a/drivers/net/dsa/mt7530.h
+++ b/drivers/net/dsa/mt7530.h
@@ -67,6 +67,11 @@ enum mt753x_id {
 #define MT753X_BPC			0x24
 #define  MT753X_BPDU_PORT_FW_MASK	GENMASK(2, 0)
 
+/* Register for :03 and :0E MAC DA frame control */
+#define MT753X_RGAC2			0x2c
+#define  MT753X_R0E_PORT_FW_MASK	GENMASK(18, 16)
+#define  MT753X_R0E_PORT_FW(x)		FIELD_PREP(MT753X_R0E_PORT_FW_MASK, x)
+
 enum mt753x_bpdu_port_fw {
 	MT753X_BPDU_FOLLOW_MFC,
 	MT753X_BPDU_CPU_EXCLUDE = 4,
-- 
2.39.2