net: mscc: ocelot: eliminate confusion between CPU and NPI port

Ocelot has the concept of a CPU port. The CPU port is represented in the
forwarding and the queueing system, but it is not a physical device. The
CPU port can either be accessed via register-based injection/extraction
(which is the case of Ocelot), via Frame-DMA (similar to the first one),
or "connected" to a physical Ethernet port (called NPI in the datasheet)
which is the case of the Felix DSA switch.

In Ocelot the CPU port is at index 11.
In Felix the CPU port is at index 6.

The CPU bit is treated special in the forwarding, as it is never cleared
from the forwarding port mask (once added to it). Other than that, it is
treated the same as a normal front port.

Both Felix and Ocelot should use the CPU port in the same way. This
means that Felix should not use the NPI port directly when forwarding to
the CPU, but instead use the CPU port.

This patch is fixing this such that Felix will use port 6 as its CPU
port, and just use the NPI port to carry the traffic.

Therefore, eliminate the "ocelot->cpu" variable which was holding the
index of the NPI port for Felix, and the index of the CPU port module
for Ocelot, so the variable was actually configuring different things
for different drivers and causing at least part of the confusion.

Also remove the "ocelot->num_cpu_ports" variable, which is the result of
another confusion. The 2 CPU ports mentioned in the datasheet are
because there are two frame extraction channels (register based or DMA
based). This is of no relevance to the driver at the moment, and
invisible to the analyzer module.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Suggested-by: Allan W. Nielsen <allan.nielsen@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/ocelot/felix.c

@@ -516,8 +516,9 @@ static int felix_setup(struct dsa_switch *ds)
 	for (port = 0; port < ds->num_ports; port++) {
 		ocelot_init_port(ocelot, port);
 
+		/* Bring up the CPU port module and configure the NPI port */
 		if (dsa_is_cpu_port(ds, port))
-			ocelot_set_cpu_port(ocelot, port,
+			ocelot_configure_cpu(ocelot, port,
 					     OCELOT_TAG_PREFIX_NONE,
 					     OCELOT_TAG_PREFIX_LONG);
 	}

drivers/net/ethernet/mscc/ocelot.c

@@ -1413,7 +1413,7 @@ void ocelot_bridge_stp_state_set(struct ocelot *ocelot, int port, u8 state)
 	 * a source for the other ports.
 	 */
 	for (p = 0; p < ocelot->num_phys_ports; p++) {
-		if (p == ocelot->cpu || (ocelot->bridge_fwd_mask & BIT(p))) {
+		if (ocelot->bridge_fwd_mask & BIT(p)) {
 			unsigned long mask = ocelot->bridge_fwd_mask & ~BIT(p);
 
 			for (i = 0; i < ocelot->num_phys_ports; i++) {
@@ -1428,18 +1428,10 @@ void ocelot_bridge_stp_state_set(struct ocelot *ocelot, int port, u8 state)
 				}
 			}
 
-			/* Avoid the NPI port from looping back to itself */
-			if (p != ocelot->cpu)
-				mask |= BIT(ocelot->cpu);
-
 			ocelot_write_rix(ocelot, mask,
 					 ANA_PGID_PGID, PGID_SRC + p);
 		} else {
-			/* Only the CPU port, this is compatible with link
-			 * aggregation.
-			 */
-			ocelot_write_rix(ocelot,
-					 BIT(ocelot->cpu),
+			ocelot_write_rix(ocelot, 0,
 					 ANA_PGID_PGID, PGID_SRC + p);
 		}
 	}
@@ -2308,27 +2300,34 @@ int ocelot_probe_port(struct ocelot *ocelot, u8 port,
 }
 EXPORT_SYMBOL(ocelot_probe_port);
 
-void ocelot_set_cpu_port(struct ocelot *ocelot, int cpu,
+/* Configure and enable the CPU port module, which is a set of queues.
+ * If @npi contains a valid port index, the CPU port module is connected
+ * to the Node Processor Interface (NPI). This is the mode through which
+ * frames can be injected from and extracted to an external CPU,
+ * over Ethernet.
+ */
+void ocelot_configure_cpu(struct ocelot *ocelot, int npi,
 			  enum ocelot_tag_prefix injection,
 			  enum ocelot_tag_prefix extraction)
 {
-	/* Configure and enable the CPU port. */
+	int cpu = ocelot->num_phys_ports;
+
+	/* The unicast destination PGID for the CPU port module is unused */
 	ocelot_write_rix(ocelot, 0, ANA_PGID_PGID, cpu);
+	/* Instead set up a multicast destination PGID for traffic copied to
+	 * the CPU. Whitelisted MAC addresses like the port netdevice MAC
+	 * addresses will be copied to the CPU via this PGID.
+	 */
 	ocelot_write_rix(ocelot, BIT(cpu), ANA_PGID_PGID, PGID_CPU);
 	ocelot_write_gix(ocelot, ANA_PORT_PORT_CFG_RECV_ENA |
 			 ANA_PORT_PORT_CFG_PORTID_VAL(cpu),
 			 ANA_PORT_PORT_CFG, cpu);
 
-	/* If the CPU port is a physical port, set up the port in Node
-	 * Processor Interface (NPI) mode. This is the mode through which
-	 * frames can be injected from and extracted to an external CPU.
-	 * Only one port can be an NPI at the same time.
-	 */
-	if (cpu < ocelot->num_phys_ports) {
+	if (npi >= 0 && npi < ocelot->num_phys_ports) {
 		int mtu = VLAN_ETH_FRAME_LEN + OCELOT_TAG_LEN;
 
 		ocelot_write(ocelot, QSYS_EXT_CPU_CFG_EXT_CPUQ_MSK_M |
-			     QSYS_EXT_CPU_CFG_EXT_CPU_PORT(cpu),
+			     QSYS_EXT_CPU_CFG_EXT_CPU_PORT(npi),
 			     QSYS_EXT_CPU_CFG);
 
 		if (injection == OCELOT_TAG_PREFIX_SHORT)
@@ -2336,14 +2335,27 @@ void ocelot_set_cpu_port(struct ocelot *ocelot, int cpu,
 		else if (injection == OCELOT_TAG_PREFIX_LONG)
 			mtu += OCELOT_LONG_PREFIX_LEN;
 
-		ocelot_port_set_mtu(ocelot, cpu, mtu);
+		ocelot_port_set_mtu(ocelot, npi, mtu);
+
+		/* Enable NPI port */
+		ocelot_write_rix(ocelot,
+				 QSYS_SWITCH_PORT_MODE_INGRESS_DROP_MODE |
+				 QSYS_SWITCH_PORT_MODE_SCH_NEXT_CFG(1) |
+				 QSYS_SWITCH_PORT_MODE_PORT_ENA,
+				 QSYS_SWITCH_PORT_MODE, npi);
+		/* NPI port Injection/Extraction configuration */
+		ocelot_write_rix(ocelot,
+				 SYS_PORT_MODE_INCL_XTR_HDR(extraction) |
+				 SYS_PORT_MODE_INCL_INJ_HDR(injection),
+				 SYS_PORT_MODE, npi);
 	}
 
-	/* CPU port Injection/Extraction configuration */
+	/* Enable CPU port module */
 	ocelot_write_rix(ocelot, QSYS_SWITCH_PORT_MODE_INGRESS_DROP_MODE |
 			 QSYS_SWITCH_PORT_MODE_SCH_NEXT_CFG(1) |
 			 QSYS_SWITCH_PORT_MODE_PORT_ENA,
 			 QSYS_SWITCH_PORT_MODE, cpu);
+	/* CPU port Injection/Extraction configuration */
 	ocelot_write_rix(ocelot, SYS_PORT_MODE_INCL_XTR_HDR(extraction) |
 			 SYS_PORT_MODE_INCL_INJ_HDR(injection),
 			 SYS_PORT_MODE, cpu);
@@ -2353,10 +2365,8 @@ void ocelot_set_cpu_port(struct ocelot *ocelot, int cpu,
 				 ANA_PORT_VLAN_CFG_VLAN_AWARE_ENA |
 				 ANA_PORT_VLAN_CFG_VLAN_POP_CNT(1),
 			 ANA_PORT_VLAN_CFG, cpu);
-
-	ocelot->cpu = cpu;
 }
-EXPORT_SYMBOL(ocelot_set_cpu_port);
+EXPORT_SYMBOL(ocelot_configure_cpu);
 
 int ocelot_init(struct ocelot *ocelot)
 {

drivers/net/ethernet/mscc/ocelot_board.c

@@ -453,8 +453,6 @@ static int mscc_ocelot_probe(struct platform_device *pdev)
 		ocelot->ptp = 1;
 	}
 
-	ocelot->num_cpu_ports = 1; /* 1 port on the switch, two groups */
-
 	ports = of_get_child_by_name(np, "ethernet-ports");
 	if (!ports) {
 		dev_err(&pdev->dev, "no ethernet-ports child node found\n");
@@ -471,8 +469,9 @@ static int mscc_ocelot_probe(struct platform_device *pdev)
 	ocelot->vcap = vsc7514_vcap_props;
 
 	ocelot_init(ocelot);
-	ocelot_set_cpu_port(ocelot, ocelot->num_phys_ports,
-			    OCELOT_TAG_PREFIX_NONE, OCELOT_TAG_PREFIX_NONE);
+	/* No NPI port */
+	ocelot_configure_cpu(ocelot, -1, OCELOT_TAG_PREFIX_NONE,
+			     OCELOT_TAG_PREFIX_NONE);
 
 	for_each_available_child_of_node(ports, portnp) {
 		struct ocelot_port_private *priv;

include/soc/mscc/ocelot.h

@@ -451,9 +451,11 @@ struct ocelot {
 	/* Keep track of the vlan port masks */
 	u32				vlan_mask[VLAN_N_VID];
 
+	/* In tables like ANA:PORT and the ANA:PGID:PGID mask,
+	 * the CPU is located after the physical ports (at the
+	 * num_phys_ports index).
+	 */
 	u8				num_phys_ports;
-	u8				num_cpu_ports;
-	u8				cpu;
 
 	u32				*lags;
 
@@ -508,7 +510,7 @@ void __ocelot_rmw_ix(struct ocelot *ocelot, u32 val, u32 mask, u32 reg,
 int ocelot_regfields_init(struct ocelot *ocelot,
 			  const struct reg_field *const regfields);
 struct regmap *ocelot_regmap_init(struct ocelot *ocelot, struct resource *res);
-void ocelot_set_cpu_port(struct ocelot *ocelot, int cpu,
+void ocelot_configure_cpu(struct ocelot *ocelot, int npi,
 			  enum ocelot_tag_prefix injection,
 			  enum ocelot_tag_prefix extraction);
 int ocelot_init(struct ocelot *ocelot);

net/dsa/tag_ocelot.c

@@ -153,7 +153,8 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
 
 	memset(injection, 0, OCELOT_TAG_LEN);
 
-	src = dsa_upstream_port(ds, port);
+	/* Set the source port as the CPU port module and not the NPI port */
+	src = ocelot->num_phys_ports;
 	dest = BIT(port);
 	bypass = true;
 	qos_class = skb->priority;