net: dsa: lantiq_gswip: drop untagged on VLAN-aware bridge ports with no PVID

Implement the required functionality, as written in
Documentation/networking/switchdev.rst section "Bridge VLAN filtering",
by using the "VLAN Ingress Tag Rule" feature of the switch.

The bit field definitions for this were found while browsing the Intel
dual BSD/GPLv2 licensed drivers for this switch IP.

Signed-off-by: Vladimir Oltean <[email protected]>
Signed-off-by: Daniel Golle <[email protected]>
Link: https://patch.msgid.link/787aa807d00b726d75db2a40add215c8b8ba7466.1760566491.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <[email protected]>

Author: vladimiroltean

drivers/net/dsa/lantiq/lantiq_gswip.c

@@ -551,6 +551,7 @@ static void gswip_port_commit_pvid(struct gswip_priv *priv, int port)
 {
 	struct dsa_port *dp = dsa_to_port(priv->ds, port);
 	struct net_device *br = dsa_port_bridge_dev_get(dp);
+	u32 vinr;
 	int idx;
 
 	if (!dsa_port_is_user(dp))
@@ -582,6 +583,11 @@ static void gswip_port_commit_pvid(struct gswip_priv *priv, int port)
 		idx = port + 1;
 	}
 
+	vinr = idx ? GSWIP_PCE_VCTRL_VINR_ALL : GSWIP_PCE_VCTRL_VINR_TAGGED;
+	gswip_switch_mask(priv, GSWIP_PCE_VCTRL_VINR,
+			  FIELD_PREP(GSWIP_PCE_VCTRL_VINR, vinr),
+			  GSWIP_PCE_VCTRL(port));
+
 	/* GSWIP 2.2 (GRX300) and later program here the VID directly. */
 	gswip_switch_w(priv, idx, GSWIP_PCE_DEFPVID(port));
 }

drivers/net/dsa/lantiq/lantiq_gswip.h

@@ -159,6 +159,10 @@
 #define  GSWIP_PCE_PCTRL_0_PSTATE_MASK	GENMASK(2, 0)
 #define GSWIP_PCE_VCTRL(p)		(0x485 + ((p) * 0xA))
 #define  GSWIP_PCE_VCTRL_UVR		BIT(0)	/* Unknown VLAN Rule */
+#define  GSWIP_PCE_VCTRL_VINR		GENMASK(2, 1) /* VLAN Ingress Tag Rule */
+#define  GSWIP_PCE_VCTRL_VINR_ALL	0 /* Admit tagged and untagged packets */
+#define  GSWIP_PCE_VCTRL_VINR_TAGGED	1 /* Admit only tagged packets */
+#define  GSWIP_PCE_VCTRL_VINR_UNTAGGED	2 /* Admit only untagged packets */
 #define  GSWIP_PCE_VCTRL_VIMR		BIT(3)	/* VLAN Ingress Member violation rule */
 #define  GSWIP_PCE_VCTRL_VEMR		BIT(4)	/* VLAN Egress Member violation rule */
 #define  GSWIP_PCE_VCTRL_VSR		BIT(5)	/* VLAN Security */