[PATCH net v4 5/7] 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).

The mt753x_bpdu_port_fw enum is universally used for trapping frames,
therefore rename it and the values in it to mt753x_port_fw.

For MT7530, LLDP frames received from a user port will be trapped to the
numerically smallest CPU port which is affine to the DSA conduit interface
that is up.

For MT7531 and the switch on the MT7988 SoC, LLDP frames received from a
user port will be trapped to the CPU port that is affine to the user port
from which the frames are received.

The bit for R0E_MANG_FR is 27. When set, the switch regards the frames with
:0E MAC DA as management (LLDP) frames. This bit is set to 1 after reset on
MT7530 and MT7531 according to the documents MT7620 Programming Guide v1.0
and MT7531 Reference Manual for Development Board v1.0, so there's no need
to deal with this bit. Since there's currently no public document for the
switch on the MT7988 SoC, I assume this is also the case for this switch.

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 | 12 ++++++++++--
 drivers/net/dsa/mt7530.h | 19 ++++++++++++-------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index e4c169843f2e..8388b058fbe4 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -2261,7 +2261,11 @@ mt7530_setup(struct dsa_switch *ds)
 
 	/* Trap BPDUs to the CPU port */
 	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
-		   MT753X_BPDU_CPU_ONLY);
+		   MT753X_PORT_FW_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_PORT_FW_CPU_ONLY));
 
 	/* Enable and reset MIB counters */
 	mt7530_mib_reset(ds);
@@ -2364,7 +2368,11 @@ mt7531_setup_common(struct dsa_switch *ds)
 
 	/* Trap BPDUs to the CPU port(s) */
 	mt7530_rmw(priv, MT753X_BPC, MT753X_BPDU_PORT_FW_MASK,
-		   MT753X_BPDU_CPU_ONLY);
+		   MT753X_PORT_FW_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_PORT_FW_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 28dbd131a535..5f048af2d89f 100644
--- a/drivers/net/dsa/mt7530.h
+++ b/drivers/net/dsa/mt7530.h
@@ -63,16 +63,21 @@ enum mt753x_id {
 #define MT753X_MIRROR_MASK(id)		((((id) == ID_MT7531) || ((id) == ID_MT7988)) ?	\
 					 MT7531_MIRROR_MASK : MIRROR_MASK)
 
-/* Registers for BPDU and PAE frame control*/
+/* Register for BPDU and PAE frame control */
 #define MT753X_BPC			0x24
 #define  MT753X_BPDU_PORT_FW_MASK	GENMASK(2, 0)
 
-enum mt753x_bpdu_port_fw {
-	MT753X_BPDU_FOLLOW_MFC,
-	MT753X_BPDU_CPU_EXCLUDE = 4,
-	MT753X_BPDU_CPU_INCLUDE = 5,
-	MT753X_BPDU_CPU_ONLY = 6,
-	MT753X_BPDU_DROP = 7,
+/* 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_port_fw {
+	MT753X_PORT_FW_FOLLOW_MFC,
+	MT753X_PORT_FW_CPU_EXCLUDE = 4,
+	MT753X_PORT_FW_CPU_INCLUDE = 5,
+	MT753X_PORT_FW_CPU_ONLY = 6,
+	MT753X_PORT_FW_DROP = 7,
 };
 
 /* Registers for address table access */
-- 
2.39.2