net: dsa: sja1105: Configure the Time-Aware Scheduler via tc-taprio offload

This qdisc offload is the closest thing to what the SJA1105 supports in
hardware for time-based egress shaping. The switch core really is built
around SAE AS6802/TTEthernet (a TTTech standard) but can be made to
operate similarly to IEEE 802.1Qbv with some constraints:

- The gate control list is a global list for all ports. There are 8
  execution threads that iterate through this global list in parallel.
  I don't know why 8, there are only 4 front-panel ports.

- Care must be taken by the user to make sure that two execution threads
  never get to execute a GCL entry simultaneously. I created a O(n^4)
  checker for this hardware limitation, prior to accepting a taprio
  offload configuration as valid.

- The spec says that if a GCL entry's interval is shorter than the frame
  length, you shouldn't send it (and end up in head-of-line blocking).
  Well, this switch does anyway.

- The switch has no concept of ADMIN and OPER configurations. Because
  it's so simple, the TAS settings are loaded through the static config
  tables interface, so there isn't even place for any discussion about
  'graceful switchover between ADMIN and OPER'. You just reset the
  switch and upload a new OPER config.

- The switch accepts multiple time sources for the gate events. Right
  now I am using the standalone clock source as opposed to PTP. So the
  base time parameter doesn't really do much. Support for the PTP clock
  source will be added in a future series.

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

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c
index 108f62c27c28..b9def744bcb3 100644
--- a/drivers/net/dsa/sja1105/sja1105_main.c
+++ b/drivers/net/dsa/sja1105/sja1105_main.c
@@ -22,6 +22,7 @@
 #include <linux/if_ether.h>
 #include <linux/dsa/8021q.h>
 #include "sja1105.h"
+#include "sja1105_tas.h"
 
 static void sja1105_hw_reset(struct gpio_desc *gpio, unsigned int pulse_len,
 			     unsigned int startup_delay)
@@ -1382,7 +1383,7 @@ static void sja1105_bridge_leave(struct dsa_switch *ds, int port,
  * modify at runtime (currently only MAC) and restore them after uploading,
  * such that this operation is relatively seamless.
  */
-static int sja1105_static_config_reload(struct sja1105_private *priv)
+int sja1105_static_config_reload(struct sja1105_private *priv)
 {
 	struct sja1105_mac_config_entry *mac;
 	int speed_mbps[SJA1105_NUM_PORTS];
@@ -1727,6 +1728,7 @@ static void sja1105_teardown(struct dsa_switch *ds)
 {
 	struct sja1105_private *priv = ds->priv;
 
+	sja1105_tas_teardown(ds);
 	cancel_work_sync(&priv->tagger_data.rxtstamp_work);
 	skb_queue_purge(&priv->tagger_data.skb_rxtstamp_queue);
 	sja1105_ptp_clock_unregister(priv);
@@ -2056,6 +2058,18 @@ static bool sja1105_port_txtstamp(struct dsa_switch *ds, int port,
 	return true;
 }
 
+static int sja1105_port_setup_tc(struct dsa_switch *ds, int port,
+				 enum tc_setup_type type,
+				 void *type_data)
+{
+	switch (type) {
+	case TC_SETUP_QDISC_TAPRIO:
+		return sja1105_setup_tc_taprio(ds, port, type_data);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static const struct dsa_switch_ops sja1105_switch_ops = {
 	.get_tag_protocol	= sja1105_get_tag_protocol,
 	.setup			= sja1105_setup,
@@ -2088,6 +2102,7 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
 	.port_hwtstamp_set	= sja1105_hwtstamp_set,
 	.port_rxtstamp		= sja1105_port_rxtstamp,
 	.port_txtstamp		= sja1105_port_txtstamp,
+	.port_setup_tc		= sja1105_port_setup_tc,
 };
 
 static int sja1105_check_device_id(struct sja1105_private *priv)
@@ -2197,6 +2212,8 @@ static int sja1105_probe(struct spi_device *spi)
 	}
 	mutex_init(&priv->mgmt_lock);
 
+	sja1105_tas_setup(ds);
+
 	return dsa_register_switch(priv->ds);
 }