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, 6 insertions, 0 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105.h b/drivers/net/dsa/sja1105/sja1105.h
index 78094db32622..e53e494c22e0 100644
--- a/drivers/net/dsa/sja1105/sja1105.h
+++ b/drivers/net/dsa/sja1105/sja1105.h
@@ -20,6 +20,8 @@
  */
 #define SJA1105_AGEING_TIME_MS(ms)	((ms) / 10)
 
+#include "sja1105_tas.h"
+
 /* Keeps the different addresses between E/T and P/Q/R/S */
 struct sja1105_regs {
 	u64 device_id;
@@ -104,6 +106,7 @@ struct sja1105_private {
 	 */
 	struct mutex mgmt_lock;
 	struct sja1105_tagger_data tagger_data;
+	struct sja1105_tas_data tas_data;
 };
 
 #include "sja1105_dynamic_config.h"
@@ -120,6 +123,9 @@ typedef enum {
 	SPI_WRITE = 1,
 } sja1105_spi_rw_mode_t;
 
+/* From sja1105_main.c */
+int sja1105_static_config_reload(struct sja1105_private *priv);
+
 /* From sja1105_spi.c */
 int sja1105_spi_send_packed_buf(const struct sja1105_private *priv,
 				sja1105_spi_rw_mode_t rw, u64 reg_addr,