net: dsa: sja1105: Add support for traffic through standalone ports

In order to support this, we are creating a make-shift switch tag out of
a VLAN trunk configured on the CPU port. Termination of normal traffic
on switch ports only works when not under a vlan_filtering bridge.
Termination of management (PTP, BPDU) traffic works under all
circumstances because it uses a different tagging mechanism
(incl_srcpt). We are making use of the generic CONFIG_NET_DSA_TAG_8021Q
code and leveraging it from our own CONFIG_NET_DSA_TAG_SJA1105.

There are two types of traffic: regular and link-local.

The link-local traffic received on the CPU port is trapped from the
switch's regular forwarding decisions because it matched one of the two
DMAC filters for management traffic.

On transmission, the switch requires special massaging for these
link-local frames. Due to a weird implementation of the switching IP, by
default it drops link-local frames that originate on the CPU port.
It needs to be told where to forward them to, through an SPI command
("management route") that is valid for only a single frame.
So when we're sending link-local traffic, we are using the
dsa_defer_xmit mechanism.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 139 insertions, 6 deletions

diff --git a/drivers/net/dsa/sja1105/Kconfig b/drivers/net/dsa/sja1105/Kconfig
index 038685bb9d57..757751a89819 100644
--- a/drivers/net/dsa/sja1105/Kconfig
+++ b/drivers/net/dsa/sja1105/Kconfig
@@ -1,6 +1,7 @@
 config NET_DSA_SJA1105
 tristate "NXP SJA1105 Ethernet switch family support"
 	depends on NET_DSA && SPI
+	select NET_DSA_TAG_SJA1105
 	select PACKING
 	select CRC32
 	help
diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h
index b0a155b57e17..b043bfc408f2 100644
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -7,6 +7,7 @@
 
 #include <linux/dsa/sja1105.h>
 #include <net/dsa.h>
+#include <linux/mutex.h>
 #include "sja1105_static_config.h"
 
 #define SJA1105_NUM_PORTS		5
@@ -65,6 +66,11 @@ struct sja1105_private {
 	struct gpio_desc *reset_gpio;
 	struct spi_device *spidev;
 	struct dsa_switch *ds;
+	struct sja1105_port ports[SJA1105_NUM_PORTS];
+	/* Serializes transmission of management frames so that
+	 * the switch doesn't confuse them with one another.
+	 */
+	struct mutex mgmt_lock;
 };
 
 #include "sja1105_dynamic_config.h"
diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 74f8ff9e17e0..785bb42cb993 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -20,6 +20,7 @@
 #include <linux/netdevice.h>
 #include <linux/if_bridge.h>
 #include <linux/if_ether.h>
+#include <linux/dsa/8021q.h>
 #include "sja1105.h"
 
 static void sja1105_hw_reset(struct gpio_desc *gpio, unsigned int pulse_len,
@@ -406,11 +407,14 @@ static int sja1105_init_general_params(struct sja1105_private *priv)
 		.tpid2 = ETH_P_SJA1105,
 	};
 	struct sja1105_table *table;
-	int i;
+	int i, k = 0;
 
-	for (i = 0; i < SJA1105_NUM_PORTS; i++)
+	for (i = 0; i < SJA1105_NUM_PORTS; i++) {
 		if (dsa_is_dsa_port(priv->ds, i))
 			default_general_params.casc_port = i;
+		else if (dsa_is_user_port(priv->ds, i))
+			priv->ports[i].mgmt_slot = k++;
+	}
 
 	table = &priv->static_config.tables[BLK_IDX_GENERAL_PARAMS];
 
@@ -1146,10 +1150,27 @@ static int sja1105_vlan_apply(struct sja1105_private *priv, int port, u16 vid,
 	return 0;
 }
 
+static int sja1105_setup_8021q_tagging(struct dsa_switch *ds, bool enabled)
+{
+	int rc, i;
+
+	for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+		rc = dsa_port_setup_8021q_tagging(ds, i, enabled);
+		if (rc < 0) {
+			dev_err(ds->dev, "Failed to setup VLAN tagging for port %d: %d\n",
+				i, rc);
+			return rc;
+		}
+	}
+	dev_info(ds->dev, "%s switch tagging\n",
+		 enabled ? "Enabled" : "Disabled");
+	return 0;
+}
+
 static enum dsa_tag_protocol
 sja1105_get_tag_protocol(struct dsa_switch *ds, int port)
 {
-	return DSA_TAG_PROTO_NONE;
+	return DSA_TAG_PROTO_SJA1105;
 }
 
 /* This callback needs to be present */
@@ -1173,7 +1194,11 @@ static int sja1105_vlan_filtering(struct dsa_switch *ds, int port, bool enabled)
 	if (rc)
 		dev_err(ds->dev, "Failed to change VLAN Ethertype\n");
 
-	return rc;
+	/* Switch port identification based on 802.1Q is only passable
+	 * if we are not under a vlan_filtering bridge. So make sure
+	 * the two configurations are mutually exclusive.
+	 */
+	return sja1105_setup_8021q_tagging(ds, !enabled);
 }
 
 static void sja1105_vlan_add(struct dsa_switch *ds, int port,
@@ -1276,7 +1301,98 @@ static int sja1105_setup(struct dsa_switch *ds)
 	 */
 	ds->vlan_filtering_is_global = true;
 
-	return 0;
+	/* The DSA/switchdev model brings up switch ports in standalone mode by
+	 * default, and that means vlan_filtering is 0 since they're not under
+	 * a bridge, so it's safe to set up switch tagging at this time.
+	 */
+	return sja1105_setup_8021q_tagging(ds, true);
+}
+
+static int sja1105_mgmt_xmit(struct dsa_switch *ds, int port, int slot,
+			     struct sk_buff *skb)
+{
+	struct sja1105_mgmt_entry mgmt_route = {0};
+	struct sja1105_private *priv = ds->priv;
+	struct ethhdr *hdr;
+	int timeout = 10;
+	int rc;
+
+	hdr = eth_hdr(skb);
+
+	mgmt_route.macaddr = ether_addr_to_u64(hdr->h_dest);
+	mgmt_route.destports = BIT(port);
+	mgmt_route.enfport = 1;
+
+	rc = sja1105_dynamic_config_write(priv, BLK_IDX_MGMT_ROUTE,
+					  slot, &mgmt_route, true);
+	if (rc < 0) {
+		kfree_skb(skb);
+		return rc;
+	}
+
+	/* Transfer skb to the host port. */
+	dsa_enqueue_skb(skb, ds->ports[port].slave);
+
+	/* Wait until the switch has processed the frame */
+	do {
+		rc = sja1105_dynamic_config_read(priv, BLK_IDX_MGMT_ROUTE,
+						 slot, &mgmt_route);
+		if (rc < 0) {
+			dev_err_ratelimited(priv->ds->dev,
+					    "failed to poll for mgmt route\n");
+			continue;
+		}
+
+		/* UM10944: The ENFPORT flag of the respective entry is
+		 * cleared when a match is found. The host can use this
+		 * flag as an acknowledgment.
+		 */
+		cpu_relax();
+	} while (mgmt_route.enfport && --timeout);
+
+	if (!timeout) {
+		/* Clean up the management route so that a follow-up
+		 * frame may not match on it by mistake.
+		 */
+		sja1105_dynamic_config_write(priv, BLK_IDX_MGMT_ROUTE,
+					     slot, &mgmt_route, false);
+		dev_err_ratelimited(priv->ds->dev, "xmit timed out\n");
+	}
+
+	return NETDEV_TX_OK;
+}
+
+/* Deferred work is unfortunately necessary because setting up the management
+ * route cannot be done from atomit context (SPI transfer takes a sleepable
+ * lock on the bus)
+ */
+static netdev_tx_t sja1105_port_deferred_xmit(struct dsa_switch *ds, int port,
+					      struct sk_buff *skb)
+{
+	struct sja1105_private *priv = ds->priv;
+	struct sja1105_port *sp = &priv->ports[port];
+	int slot = sp->mgmt_slot;
+
+	/* The tragic fact about the switch having 4x2 slots for installing
+	 * management routes is that all of them except one are actually
+	 * useless.
+	 * If 2 slots are simultaneously configured for two BPDUs sent to the
+	 * same (multicast) DMAC but on different egress ports, the switch
+	 * would confuse them and redirect first frame it receives on the CPU
+	 * port towards the port configured on the numerically first slot
+	 * (therefore wrong port), then second received frame on second slot
+	 * (also wrong port).
+	 * So for all practical purposes, there needs to be a lock that
+	 * prevents that from happening. The slot used here is utterly useless
+	 * (could have simply been 0 just as fine), but we are doing it
+	 * nonetheless, in case a smarter idea ever comes up in the future.
+	 */
+	mutex_lock(&priv->mgmt_lock);
+
+	sja1105_mgmt_xmit(ds, port, slot, skb);
+
+	mutex_unlock(&priv->mgmt_lock);
+	return NETDEV_TX_OK;
 }
 
 /* The MAXAGE setting belongs to the L2 Forwarding Parameters table,
@@ -1324,6 +1440,7 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
 	.port_mdb_prepare	= sja1105_mdb_prepare,
 	.port_mdb_add		= sja1105_mdb_add,
 	.port_mdb_del		= sja1105_mdb_del,
+	.port_deferred_xmit	= sja1105_port_deferred_xmit,
 };
 
 static int sja1105_check_device_id(struct sja1105_private *priv)
@@ -1367,7 +1484,7 @@ static int sja1105_probe(struct spi_device *spi)
 	struct device *dev = &spi->dev;
 	struct sja1105_private *priv;
 	struct dsa_switch *ds;
-	int rc;
+	int rc, i;
 
 	if (!dev->of_node) {
 		dev_err(dev, "No DTS bindings for SJA1105 driver\n");
@@ -1418,6 +1535,15 @@ static int sja1105_probe(struct spi_device *spi)
 	ds->priv = priv;
 	priv->ds = ds;
 
+	/* Connections between dsa_port and sja1105_port */
+	for (i = 0; i < SJA1105_NUM_PORTS; i++) {
+		struct sja1105_port *sp = &priv->ports[i];
+
+		ds->ports[i].priv = sp;
+		sp->dp = &ds->ports[i];
+	}
+	mutex_init(&priv->mgmt_lock);
+
 	return dsa_register_switch(priv->ds);
 }