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>

drivers/net/dsa/sja1105/Kconfig

@@ -28,6 +28,7 @@ config NET_DSA_SJA1105_TAS
 	bool "Support for the Time-Aware Scheduler on NXP SJA1105"
 	depends on NET_DSA_SJA1105 && NET_SCH_TAPRIO
 	depends on NET_SCH_TAPRIO=y || NET_DSA_SJA1105=m
+	depends on NET_DSA_SJA1105_PTP
 	help
 	  This enables support for the TTEthernet-based egress scheduling
 	  engine in the SJA1105 DSA driver, which is controlled using a

drivers/net/dsa/sja1105/sja1105.h

@@ -40,6 +40,8 @@ struct sja1105_regs {
 	u64 ptp_control;
 	u64 ptpclkval;
 	u64 ptpclkrate;
+	u64 ptpclkcorp;
+	u64 ptpschtm;
 	u64 ptpegr_ts[SJA1105_NUM_PORTS];
 	u64 pad_mii_tx[SJA1105_NUM_PORTS];
 	u64 pad_mii_id[SJA1105_NUM_PORTS];

drivers/net/dsa/sja1105/sja1105_ptp.c

@@ -201,6 +201,8 @@ void sja1105et_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
 	u64 valid = 1;
 
 	sja1105_packing(buf, &valid,           31, 31, size, op);
+	sja1105_packing(buf, &cmd->ptpstrtsch, 30, 30, size, op);
+	sja1105_packing(buf, &cmd->ptpstopsch, 29, 29, size, op);
 	sja1105_packing(buf, &cmd->resptp,      2,  2, size, op);
 	sja1105_packing(buf, &cmd->corrclk4ts,  1,  1, size, op);
 	sja1105_packing(buf, &cmd->ptpclkadd,   0,  0, size, op);
@@ -214,15 +216,17 @@ void sja1105pqrs_ptp_cmd_packing(u8 *buf, struct sja1105_ptp_cmd *cmd,
 	u64 valid = 1;
 
 	sja1105_packing(buf, &valid,           31, 31, size, op);
+	sja1105_packing(buf, &cmd->ptpstrtsch, 30, 30, size, op);
+	sja1105_packing(buf, &cmd->ptpstopsch, 29, 29, size, op);
 	sja1105_packing(buf, &cmd->resptp,      3,  3, size, op);
 	sja1105_packing(buf, &cmd->corrclk4ts,  2,  2, size, op);
 	sja1105_packing(buf, &cmd->ptpclkadd,   0,  0, size, op);
 }
 
-static int sja1105_ptp_commit(struct sja1105_private *priv,
-			      struct sja1105_ptp_cmd *cmd,
-			      sja1105_spi_rw_mode_t rw)
+int sja1105_ptp_commit(struct dsa_switch *ds, struct sja1105_ptp_cmd *cmd,
+		       sja1105_spi_rw_mode_t rw)
 {
+	const struct sja1105_private *priv = ds->priv;
 	const struct sja1105_regs *regs = priv->info->regs;
 	u8 buf[SJA1105_SIZE_PTP_CMD] = {0};
 	int rc;
@@ -448,7 +452,9 @@ static int sja1105_ptp_reset(struct dsa_switch *ds)
 	cmd.resptp = 1;
 
 	dev_dbg(ds->dev, "Resetting PTP clock\n");
-	rc = sja1105_ptp_commit(priv, &cmd, SPI_WRITE);
+	rc = sja1105_ptp_commit(ds, &cmd, SPI_WRITE);
+
+	sja1105_tas_clockstep(priv->ds);
 
 	mutex_unlock(&ptp_data->lock);
 
@@ -504,7 +510,7 @@ static int sja1105_ptp_mode_set(struct sja1105_private *priv,
 
 	ptp_data->cmd.ptpclkadd = mode;
 
-	return sja1105_ptp_commit(priv, &ptp_data->cmd, SPI_WRITE);
+	return sja1105_ptp_commit(priv->ds, &ptp_data->cmd, SPI_WRITE);
 }
 
 /* Write to PTPCLKVAL while PTPCLKADD is 0 */
@@ -521,7 +527,11 @@ int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
 		return rc;
 	}
 
-	return sja1105_ptpclkval_write(priv, ticks, ptp_sts);
+	rc = sja1105_ptpclkval_write(priv, ticks, ptp_sts);
+
+	sja1105_tas_clockstep(priv->ds);
+
+	return rc;
 }
 
 static int sja1105_ptp_settime(struct ptp_clock_info *ptp,
@@ -563,6 +573,8 @@ static int sja1105_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 	rc = sja1105_xfer_u32(priv, SPI_WRITE, regs->ptpclkrate, &clkrate32,
 			      NULL);
 
+	sja1105_tas_adjfreq(priv->ds);
+
 	mutex_unlock(&ptp_data->lock);
 
 	return rc;
@@ -581,7 +593,11 @@ int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
 		return rc;
 	}
 
-	return sja1105_ptpclkval_write(priv, ticks, NULL);
+	rc = sja1105_ptpclkval_write(priv, ticks, NULL);
+
+	sja1105_tas_clockstep(priv->ds);
+
+	return rc;
 }
 
 static int sja1105_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)

drivers/net/dsa/sja1105/sja1105_ptp.h

@@ -22,6 +22,8 @@ static inline s64 sja1105_ticks_to_ns(s64 ticks)
 }
 
 struct sja1105_ptp_cmd {
+	u64 ptpstrtsch;		/* start schedule */
+	u64 ptpstopsch;		/* stop schedule */
 	u64 resptp;		/* reset */
 	u64 corrclk4ts;		/* use the corrected clock for timestamps */
 	u64 ptpclkadd;		/* enum sja1105_ptp_clk_mode */
@@ -69,6 +71,9 @@ int __sja1105_ptp_settime(struct dsa_switch *ds, u64 ns,
 
 int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta);
 
+int sja1105_ptp_commit(struct dsa_switch *ds, struct sja1105_ptp_cmd *cmd,
+		       sja1105_spi_rw_mode_t rw);
+
 #else
 
 struct sja1105_ptp_cmd;
@@ -110,6 +115,13 @@ static inline int __sja1105_ptp_adjtime(struct dsa_switch *ds, s64 delta)
 	return 0;
 }
 
+static inline int sja1105_ptp_commit(struct dsa_switch *ds,
+				     struct sja1105_ptp_cmd *cmd,
+				     sja1105_spi_rw_mode_t rw)
+{
+	return 0;
+}
+
 #define sja1105et_ptp_cmd_packing NULL
 
 #define sja1105pqrs_ptp_cmd_packing NULL

drivers/net/dsa/sja1105/sja1105_spi.c

@@ -539,9 +539,11 @@ static struct sja1105_regs sja1105et_regs = {
 	.rmii_ref_clk = {0x100015, 0x10001C, 0x100023, 0x10002A, 0x100031},
 	.rmii_ext_tx_clk = {0x100018, 0x10001F, 0x100026, 0x10002D, 0x100034},
 	.ptpegr_ts = {0xC0, 0xC2, 0xC4, 0xC6, 0xC8},
+	.ptpschtm = 0x12, /* Spans 0x12 to 0x13 */
 	.ptp_control = 0x17,
 	.ptpclkval = 0x18, /* Spans 0x18 to 0x19 */
 	.ptpclkrate = 0x1A,
+	.ptpclkcorp = 0x1D,
 };
 
 static struct sja1105_regs sja1105pqrs_regs = {
@@ -569,9 +571,11 @@ static struct sja1105_regs sja1105pqrs_regs = {
 	.rmii_ext_tx_clk = {0x100017, 0x10001D, 0x100023, 0x100029, 0x10002F},
 	.qlevel = {0x604, 0x614, 0x624, 0x634, 0x644},
 	.ptpegr_ts = {0xC0, 0xC4, 0xC8, 0xCC, 0xD0},
+	.ptpschtm = 0x13, /* Spans 0x13 to 0x14 */
 	.ptp_control = 0x18,
 	.ptpclkval = 0x19,
 	.ptpclkrate = 0x1B,
+	.ptpclkcorp = 0x1E,
 };
 
 struct sja1105_info sja1105e_info = {

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 */