[PATCH v2 net-next 3/8] net: dsa: sja1105: configure the cascade ports based on topology

Vladimir Oltean
2021-08-04T13:16:58Z

The sja1105 switch family has a feature called "cascade ports" which can
be used in topologies where multiple SJA1105/SJA1110 switches are daisy
chained. Upstream switches set this bit for the DSA link towards the
downstream switches. This is used when the upstream switch receives a
control packet (PTP, STP) from a downstream switch, because if the
source port for a control packet is marked as a cascade port, then the
source port, switch ID and RX timestamp will not be taken again on the
upstream switch, it is assumed that this has already been done by the
downstream switch (the leaf port in the tree) and that the CPU has
everything it needs to decode the information from this packet.

We need to distinguish between an upstream-facing DSA link and a
downstream-facing DSA link, because the upstream-facing DSA links are
"host ports" for the SJA1105/SJA1110 switches, and the downstream-facing
DSA links are "cascade ports".

Note that SJA1105 supports a single cascade port, so only daisy chain
topologies work. With SJA1110, there can be more complex topologies such
as:

eth0
|
host port
|
sw0p0 sw0p1 sw0p2 sw0p3 sw0p4
| | | |
cascade cascade user user
port port port port
| |
| |
| |
| host
| port
| |
| sw1p0 sw1p1 sw1p2 sw1p3 sw1p4
| | | | |
| user user user user
host port port port port
port
|
sw2p0 sw2p1 sw2p2 sw2p3 sw2p4
| | | |
user user user user
port port port port

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/net/dsa/sja1105/sja1105_main.c | 97 +++++++++++++++++++-------
1 file changed, 70 insertions(+), 27 deletions(-)

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 5ab1676a7448..74cd5bf7abc6 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -688,6 +688,72 @@ static void sja1110_select_tdmaconfigidx(struct sja1105_private *priv)
general_params->tdmaconfigidx = tdmaconfigidx;
}

+static int sja1105_init_topology(struct sja1105_private *priv,
+ struct sja1105_general_params_entry *general_params)
+{
+ struct dsa_switch *ds = priv->ds;
+ int port;
+
+ /* The host port is the destination for traffic matching mac_fltres1
+ * and mac_fltres0 on all ports except itself. Default to an invalid
+ * value.
+ */
+ general_params->host_port = ds->num_ports;
+
+ /* Link-local traffic received on casc_port will be forwarded
+ * to host_port without embedding the source port and device ID
+ * info in the destination MAC address, and no RX timestamps will be
+ * taken either (presumably because it is a cascaded port and a
+ * downstream SJA switch already did that).
+ * To disable the feature, we need to do different things depending on
+ * switch generation. On SJA1105 we need to set an invalid port, while
+ * on SJA1110 which support multiple cascaded ports, this field is a
+ * bitmask so it must be left zero.
+ */
+ if (!priv->info->multiple_cascade_ports)
+ general_params->casc_port = ds->num_ports;
+
+ for (port = 0; port < ds->num_ports; port++) {
+ bool is_upstream = dsa_is_upstream_port(ds, port);
+ bool is_dsa_link = dsa_is_dsa_port(ds, port);
+
+ /* Upstream ports can be dedicated CPU ports or
+ * upstream-facing DSA links
+ */
+ if (is_upstream) {
+ if (general_params->host_port == ds->num_ports) {
+ general_params->host_port = port;
+ } else {
+ dev_err(ds->dev,
+ "Port %llu is already a host port, configuring %d as one too is not supported\n",
+ general_params->host_port, port);
+ return -EINVAL;
+ }
+ }
+
+ /* Cascade ports are downstream-facing DSA links */
+ if (is_dsa_link && !is_upstream) {
+ if (priv->info->multiple_cascade_ports) {
+ general_params->casc_port |= BIT(port);
+ } else if (general_params->casc_port == ds->num_ports) {
+ general_params->casc_port = port;
+ } else {
+ dev_err(ds->dev,
+ "Port %llu is already a cascade port, configuring %d as one too is not supported\n",
+ general_params->casc_port, port);
+ return -EINVAL;
+ }
+ }
+ }
+
+ if (general_params->host_port == ds->num_ports) {
+ dev_err(ds->dev, "No host port configured\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int sja1105_init_general_params(struct sja1105_private *priv)
{
struct sja1105_general_params_entry default_general_params = {
@@ -706,12 +772,6 @@ static int sja1105_init_general_params(struct sja1105_private *priv)
.mac_flt0 = SJA1105_LINKLOCAL_FILTER_B_MASK,
.incl_srcpt0 = false,
.send_meta0 = false,
- /* The destination for traffic matching mac_fltres1 and
- * mac_fltres0 on all ports except host_port. Such traffic
- * receieved on host_port itself would be dropped, except
- * by installing a temporary 'management route'
- */
- .host_port = priv->ds->num_ports,
/* Default to an invalid value */
.mirr_port = priv->ds->num_ports,
/* No TTEthernet */
@@ -731,16 +791,12 @@ static int sja1105_init_general_params(struct sja1105_private *priv)
.header_type = ETH_P_SJA1110,
};
struct sja1105_general_params_entry *general_params;
- struct dsa_switch *ds = priv->ds;
struct sja1105_table *table;
- int port;
+ int rc;

- for (port = 0; port < ds->num_ports; port++) {
- if (dsa_is_cpu_port(ds, port)) {
- default_general_params.host_port = port;
- break;
- }
- }
+ rc = sja1105_init_topology(priv, &default_general_params);
+ if (rc)
+ return rc;

table = &priv->static_config.tables[BLK_IDX_GENERAL_PARAMS];

@@ -763,19 +819,6 @@ static int sja1105_init_general_params(struct sja1105_private *priv)

sja1110_select_tdmaconfigidx(priv);

- /* Link-local traffic received on casc_port will be forwarded
- * to host_port without embedding the source port and device ID
- * info in the destination MAC address, and no RX timestamps will be
- * taken either (presumably because it is a cascaded port and a
- * downstream SJA switch already did that).
- * To disable the feature, we need to do different things depending on
- * switch generation. On SJA1105 we need to set an invalid port, while
- * on SJA1110 which support multiple cascaded ports, this field is a
- * bitmask so it must be left zero.
- */
- if (!priv->info->multiple_cascade_ports)
- general_params->casc_port = ds->num_ports;
-
return 0;
}

--
2.25.1