net: dsa: sja1105: Implement state machine for TAS with PTP clock source

Tested using the following bash script and the tc from iproute2-next:

	#!/bin/bash

	set -e -u -o pipefail

	NSEC_PER_SEC="1000000000"

	gatemask() {
		local tc_list="$1"
		local mask=0

		for tc in ${tc_list}; do
			mask=$((${mask} | (1 << ${tc})))
		done

		printf "%02x" ${mask}
	}

	if ! systemctl is-active --quiet ptp4l; then
		echo "Please start the ptp4l service"
		exit
	fi

	now=$(phc_ctl /dev/ptp1 get | gawk '/clock time is/ { print $5; }')
	# Phase-align the base time to the start of the next second.
	sec=$(echo "${now}" | gawk -F. '{ print $1; }')
	base_time="$(((${sec} + 1) * ${NSEC_PER_SEC}))"

	tc qdisc add dev swp5 parent root handle 100 taprio \
		num_tc 8 \
		map 0 1 2 3 5 6 7 \
		queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 \
		base-time ${base_time} \
		sched-entry S $(gatemask 7) 100000 \
		sched-entry S $(gatemask "0 1 2 3 4 5 6") 400000 \
		clockid CLOCK_TAI flags 2

The "state machine" is a workqueue invoked after each manipulation
command on the PTP clock (reset, adjust time, set time, adjust
frequency) which checks over the state of the time-aware scheduler.
So it is not monitored periodically, only in reaction to a PTP command
typically triggered from a userspace daemon (linuxptp). Otherwise there
is no reason for things to go wrong.

Now that the timecounter/cyclecounter has been replaced with hardware
operations on the PTP clock, the TAS Kconfig now depends upon PTP and
the standalone clocksource operating mode has been removed.

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

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/net/dsa/sja1105/sja1105_tas.h b/drivers/net/dsa/sja1105/sja1105_tas.h
index 0aad212d88b2..b226c3dfd5b1 100644
--- a/drivers/net/dsa/sja1105/sja1105_tas.h
+++ b/drivers/net/dsa/sja1105/sja1105_tas.h
@@ -8,8 +8,27 @@
 
 #if IS_ENABLED(CONFIG_NET_DSA_SJA1105_TAS)
 
+enum sja1105_tas_state {
+	SJA1105_TAS_STATE_DISABLED,
+	SJA1105_TAS_STATE_ENABLED_NOT_RUNNING,
+	SJA1105_TAS_STATE_RUNNING,
+};
+
+enum sja1105_ptp_op {
+	SJA1105_PTP_NONE,
+	SJA1105_PTP_CLOCKSTEP,
+	SJA1105_PTP_ADJUSTFREQ,
+};
+
 struct sja1105_tas_data {
 	struct tc_taprio_qopt_offload *offload[SJA1105_NUM_PORTS];
+	enum sja1105_tas_state state;
+	enum sja1105_ptp_op last_op;
+	struct work_struct tas_work;
+	s64 earliest_base_time;
+	s64 oper_base_time;
+	u64 max_cycle_time;
+	bool enabled;
 };
 
 int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port,
@@ -19,6 +38,10 @@ void sja1105_tas_setup(struct dsa_switch *ds);
 
 void sja1105_tas_teardown(struct dsa_switch *ds);
 
+void sja1105_tas_clockstep(struct dsa_switch *ds);
+
+void sja1105_tas_adjfreq(struct dsa_switch *ds);
+
 #else
 
 /* C doesn't allow empty structures, bah! */
@@ -36,6 +59,10 @@ static inline void sja1105_tas_setup(struct dsa_switch *ds) { }
 
 static inline void sja1105_tas_teardown(struct dsa_switch *ds) { }
 
+static inline void sja1105_tas_clockstep(struct dsa_switch *ds) { }
+
+static inline void sja1105_tas_adjfreq(struct dsa_switch *ds) { }
+
 #endif /* IS_ENABLED(CONFIG_NET_DSA_SJA1105_TAS) */
 
 #endif /* _SJA1105_TAS_H */