diff options
Diffstat (limited to 'drivers/net/dsa/sja1105/sja1105_tas.c')
| -rw-r--r-- | drivers/net/dsa/sja1105/sja1105_tas.c | 432 |
1 files changed, 420 insertions, 12 deletions
diff --git a/drivers/net/dsa/sja1105/sja1105_tas.c b/drivers/net/dsa/sja1105/sja1105_tas.c index 33eca6a82ec5..26b925b5dace 100644 --- a/drivers/net/dsa/sja1105/sja1105_tas.c +++ b/drivers/net/dsa/sja1105/sja1105_tas.c @@ -10,6 +10,11 @@ #define SJA1105_TAS_MAX_DELTA BIT(19) #define SJA1105_GATE_MASK GENMASK_ULL(SJA1105_NUM_TC - 1, 0) +#define work_to_sja1105_tas(d) \ + container_of((d), struct sja1105_tas_data, tas_work) +#define tas_to_sja1105(d) \ + container_of((d), struct sja1105_private, tas_data) + /* This is not a preprocessor macro because the "ns" argument may or may not be * s64 at caller side. This ensures it is properly type-cast before div_s64. */ @@ -18,6 +23,100 @@ static s64 ns_to_sja1105_delta(s64 ns) return div_s64(ns, 200); } +static s64 sja1105_delta_to_ns(s64 delta) +{ + return delta * 200; +} + +/* Calculate the first base_time in the future that satisfies this + * relationship: + * + * future_base_time = base_time + N x cycle_time >= now, or + * + * now - base_time + * N >= --------------- + * cycle_time + * + * Because N is an integer, the ceiling value of the above "a / b" ratio + * is in fact precisely the floor value of "(a + b - 1) / b", which is + * easier to calculate only having integer division tools. + */ +static s64 future_base_time(s64 base_time, s64 cycle_time, s64 now) +{ + s64 a, b, n; + + if (base_time >= now) + return base_time; + + a = now - base_time; + b = cycle_time; + n = div_s64(a + b - 1, b); + + return base_time + n * cycle_time; +} + +static int sja1105_tas_set_runtime_params(struct sja1105_private *priv) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct dsa_switch *ds = priv->ds; + s64 earliest_base_time = S64_MAX; + s64 latest_base_time = 0; + s64 its_cycle_time = 0; + s64 max_cycle_time = 0; + int port; + + tas_data->enabled = false; + + for (port = 0; port < SJA1105_NUM_PORTS; port++) { + const struct tc_taprio_qopt_offload *offload; + + offload = tas_data->offload[port]; + if (!offload) + continue; + + tas_data->enabled = true; + + if (max_cycle_time < offload->cycle_time) + max_cycle_time = offload->cycle_time; + if (latest_base_time < offload->base_time) + latest_base_time = offload->base_time; + if (earliest_base_time > offload->base_time) { + earliest_base_time = offload->base_time; + its_cycle_time = offload->cycle_time; + } + } + + if (!tas_data->enabled) + return 0; + + /* Roll the earliest base time over until it is in a comparable + * time base with the latest, then compare their deltas. + * We want to enforce that all ports' base times are within + * SJA1105_TAS_MAX_DELTA 200ns cycles of one another. + */ + earliest_base_time = future_base_time(earliest_base_time, + its_cycle_time, + latest_base_time); + while (earliest_base_time > latest_base_time) + earliest_base_time -= its_cycle_time; + if (latest_base_time - earliest_base_time > + sja1105_delta_to_ns(SJA1105_TAS_MAX_DELTA)) { + dev_err(ds->dev, + "Base times too far apart: min %llu max %llu\n", + earliest_base_time, latest_base_time); + return -ERANGE; + } + + tas_data->earliest_base_time = earliest_base_time; + tas_data->max_cycle_time = max_cycle_time; + + dev_dbg(ds->dev, "earliest base time %lld ns\n", earliest_base_time); + dev_dbg(ds->dev, "latest base time %lld ns\n", latest_base_time); + dev_dbg(ds->dev, "longest cycle time %lld ns\n", max_cycle_time); + + return 0; +} + /* Lo and behold: the egress scheduler from hell. * * At the hardware level, the Time-Aware Shaper holds a global linear arrray of @@ -99,7 +198,11 @@ static int sja1105_init_scheduling(struct sja1105_private *priv) int num_cycles = 0; int cycle = 0; int i, k = 0; - int port; + int port, rc; + + rc = sja1105_tas_set_runtime_params(priv); + if (rc < 0) + return rc; /* Discard previous Schedule Table */ table = &priv->static_config.tables[BLK_IDX_SCHEDULE]; @@ -184,11 +287,13 @@ static int sja1105_init_scheduling(struct sja1105_private *priv) schedule_entry_points = table->entries; /* Finally start populating the static config tables */ - schedule_entry_points_params->clksrc = SJA1105_TAS_CLKSRC_STANDALONE; + schedule_entry_points_params->clksrc = SJA1105_TAS_CLKSRC_PTP; schedule_entry_points_params->actsubsch = num_cycles - 1; for (port = 0; port < SJA1105_NUM_PORTS; port++) { const struct tc_taprio_qopt_offload *offload; + /* Relative base time */ + s64 rbt; offload = tas_data->offload[port]; if (!offload) @@ -196,15 +301,21 @@ static int sja1105_init_scheduling(struct sja1105_private *priv) schedule_start_idx = k; schedule_end_idx = k + offload->num_entries - 1; - /* TODO this is the base time for the port's subschedule, - * relative to PTPSCHTM. But as we're using the standalone - * clock source and not PTP clock as time reference, there's - * little point in even trying to put more logic into this, - * like preserving the phases between the subschedules of - * different ports. We'll get all of that when switching to the - * PTP clock source. + /* This is the base time expressed as a number of TAS ticks + * relative to PTPSCHTM, which we'll (perhaps improperly) call + * the operational base time. + */ + rbt = future_base_time(offload->base_time, + offload->cycle_time, + tas_data->earliest_base_time); + rbt -= tas_data->earliest_base_time; + /* UM10944.pdf 4.2.2. Schedule Entry Points table says that + * delta cannot be zero, which is shitty. Advance all relative + * base times by 1 TAS delta, so that even the earliest base + * time becomes 1 in relative terms. Then start the operational + * base time (PTPSCHTM) one TAS delta earlier than planned. */ - entry_point_delta = 1; + entry_point_delta = ns_to_sja1105_delta(rbt) + 1; schedule_entry_points[cycle].subschindx = cycle; schedule_entry_points[cycle].delta = entry_point_delta; @@ -352,7 +463,7 @@ int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port, if (rc < 0) return rc; - return sja1105_static_config_reload(priv); + return sja1105_static_config_reload(priv, SJA1105_SCHEDULING); } /* The cycle time extension is the amount of time the last cycle from @@ -400,11 +511,306 @@ int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port, if (rc < 0) return rc; - return sja1105_static_config_reload(priv); + return sja1105_static_config_reload(priv, SJA1105_SCHEDULING); +} + +static int sja1105_tas_check_running(struct sja1105_private *priv) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct dsa_switch *ds = priv->ds; + struct sja1105_ptp_cmd cmd = {0}; + int rc; + + rc = sja1105_ptp_commit(ds, &cmd, SPI_READ); + if (rc < 0) + return rc; + + if (cmd.ptpstrtsch == 1) + /* Schedule successfully started */ + tas_data->state = SJA1105_TAS_STATE_RUNNING; + else if (cmd.ptpstopsch == 1) + /* Schedule is stopped */ + tas_data->state = SJA1105_TAS_STATE_DISABLED; + else + /* Schedule is probably not configured with PTP clock source */ + rc = -EINVAL; + + return rc; +} + +/* Write to PTPCLKCORP */ +static int sja1105_tas_adjust_drift(struct sja1105_private *priv, + u64 correction) +{ + const struct sja1105_regs *regs = priv->info->regs; + u32 ptpclkcorp = ns_to_sja1105_ticks(correction); + + return sja1105_xfer_u32(priv, SPI_WRITE, regs->ptpclkcorp, + &ptpclkcorp, NULL); +} + +/* Write to PTPSCHTM */ +static int sja1105_tas_set_base_time(struct sja1105_private *priv, + u64 base_time) +{ + const struct sja1105_regs *regs = priv->info->regs; + u64 ptpschtm = ns_to_sja1105_ticks(base_time); + + return sja1105_xfer_u64(priv, SPI_WRITE, regs->ptpschtm, + &ptpschtm, NULL); +} + +static int sja1105_tas_start(struct sja1105_private *priv) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct sja1105_ptp_cmd *cmd = &priv->ptp_data.cmd; + struct dsa_switch *ds = priv->ds; + int rc; + + dev_dbg(ds->dev, "Starting the TAS\n"); + + if (tas_data->state == SJA1105_TAS_STATE_ENABLED_NOT_RUNNING || + tas_data->state == SJA1105_TAS_STATE_RUNNING) { + dev_err(ds->dev, "TAS already started\n"); + return -EINVAL; + } + + cmd->ptpstrtsch = 1; + cmd->ptpstopsch = 0; + + rc = sja1105_ptp_commit(ds, cmd, SPI_WRITE); + if (rc < 0) + return rc; + + tas_data->state = SJA1105_TAS_STATE_ENABLED_NOT_RUNNING; + + return 0; +} + +static int sja1105_tas_stop(struct sja1105_private *priv) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct sja1105_ptp_cmd *cmd = &priv->ptp_data.cmd; + struct dsa_switch *ds = priv->ds; + int rc; + + dev_dbg(ds->dev, "Stopping the TAS\n"); + + if (tas_data->state == SJA1105_TAS_STATE_DISABLED) { + dev_err(ds->dev, "TAS already disabled\n"); + return -EINVAL; + } + + cmd->ptpstopsch = 1; + cmd->ptpstrtsch = 0; + + rc = sja1105_ptp_commit(ds, cmd, SPI_WRITE); + if (rc < 0) + return rc; + + tas_data->state = SJA1105_TAS_STATE_DISABLED; + + return 0; +} + +/* The schedule engine and the PTP clock are driven by the same oscillator, and + * they run in parallel. But whilst the PTP clock can keep an absolute + * time-of-day, the schedule engine is only running in 'ticks' (25 ticks make + * up a delta, which is 200ns), and wrapping around at the end of each cycle. + * The schedule engine is started when the PTP clock reaches the PTPSCHTM time + * (in PTP domain). + * Because the PTP clock can be rate-corrected (accelerated or slowed down) by + * a software servo, and the schedule engine clock runs in parallel to the PTP + * clock, there is logic internal to the switch that periodically keeps the + * schedule engine from drifting away. The frequency with which this internal + * syntonization happens is the PTP clock correction period (PTPCLKCORP). It is + * a value also in the PTP clock domain, and is also rate-corrected. + * To be precise, during a correction period, there is logic to determine by + * how many scheduler clock ticks has the PTP clock drifted. At the end of each + * correction period/beginning of new one, the length of a delta is shrunk or + * expanded with an integer number of ticks, compared with the typical 25. + * So a delta lasts for 200ns (or 25 ticks) only on average. + * Sometimes it is longer, sometimes it is shorter. The internal syntonization + * logic can adjust for at most 5 ticks each 20 ticks. + * + * The first implication is that you should choose your schedule correction + * period to be an integer multiple of the schedule length. Preferably one. + * In case there are schedules of multiple ports active, then the correction + * period needs to be a multiple of them all. Given the restriction that the + * cycle times have to be multiples of one another anyway, this means the + * correction period can simply be the largest cycle time, hence the current + * choice. This way, the updates are always synchronous to the transmission + * cycle, and therefore predictable. + * + * The second implication is that at the beginning of a correction period, the + * first few deltas will be modulated in time, until the schedule engine is + * properly phase-aligned with the PTP clock. For this reason, you should place + * your best-effort traffic at the beginning of a cycle, and your + * time-triggered traffic afterwards. + * + * The third implication is that once the schedule engine is started, it can + * only adjust for so much drift within a correction period. In the servo you + * can only change the PTPCLKRATE, but not step the clock (PTPCLKADD). If you + * want to do the latter, you need to stop and restart the schedule engine, + * which is what the state machine handles. + */ +static void sja1105_tas_state_machine(struct work_struct *work) +{ + struct sja1105_tas_data *tas_data = work_to_sja1105_tas(work); + struct sja1105_private *priv = tas_to_sja1105(tas_data); + struct sja1105_ptp_data *ptp_data = &priv->ptp_data; + struct timespec64 base_time_ts, now_ts; + struct dsa_switch *ds = priv->ds; + struct timespec64 diff; + s64 base_time, now; + int rc = 0; + + mutex_lock(&ptp_data->lock); + + switch (tas_data->state) { + case SJA1105_TAS_STATE_DISABLED: + /* Can't do anything at all if clock is still being stepped */ + if (tas_data->last_op != SJA1105_PTP_ADJUSTFREQ) + break; + + rc = sja1105_tas_adjust_drift(priv, tas_data->max_cycle_time); + if (rc < 0) + break; + + rc = __sja1105_ptp_gettimex(ds, &now, NULL); + if (rc < 0) + break; + + /* Plan to start the earliest schedule first. The others + * will be started in hardware, by way of their respective + * entry points delta. + * Try our best to avoid fringe cases (race condition between + * ptpschtm and ptpstrtsch) by pushing the oper_base_time at + * least one second in the future from now. This is not ideal, + * but this only needs to buy us time until the + * sja1105_tas_start command below gets executed. + */ + base_time = future_base_time(tas_data->earliest_base_time, + tas_data->max_cycle_time, + now + 1ull * NSEC_PER_SEC); + base_time -= sja1105_delta_to_ns(1); + + rc = sja1105_tas_set_base_time(priv, base_time); + if (rc < 0) + break; + + tas_data->oper_base_time = base_time; + + rc = sja1105_tas_start(priv); + if (rc < 0) + break; + + base_time_ts = ns_to_timespec64(base_time); + now_ts = ns_to_timespec64(now); + + dev_dbg(ds->dev, "OPER base time %lld.%09ld (now %lld.%09ld)\n", + base_time_ts.tv_sec, base_time_ts.tv_nsec, + now_ts.tv_sec, now_ts.tv_nsec); + + break; + + case SJA1105_TAS_STATE_ENABLED_NOT_RUNNING: + if (tas_data->last_op != SJA1105_PTP_ADJUSTFREQ) { + /* Clock was stepped.. bad news for TAS */ + sja1105_tas_stop(priv); + break; + } + + /* Check if TAS has actually started, by comparing the + * scheduled start time with the SJA1105 PTP clock + */ + rc = __sja1105_ptp_gettimex(ds, &now, NULL); + if (rc < 0) + break; + + if (now < tas_data->oper_base_time) { + /* TAS has not started yet */ + diff = ns_to_timespec64(tas_data->oper_base_time - now); + dev_dbg(ds->dev, "time to start: [%lld.%09ld]", + diff.tv_sec, diff.tv_nsec); + break; + } + + /* Time elapsed, what happened? */ + rc = sja1105_tas_check_running(priv); + if (rc < 0) + break; + + if (tas_data->state != SJA1105_TAS_STATE_RUNNING) + /* TAS has started */ + dev_err(ds->dev, + "TAS not started despite time elapsed\n"); + + break; + + case SJA1105_TAS_STATE_RUNNING: + /* Clock was stepped.. bad news for TAS */ + if (tas_data->last_op != SJA1105_PTP_ADJUSTFREQ) { + sja1105_tas_stop(priv); + break; + } + + rc = sja1105_tas_check_running(priv); + if (rc < 0) + break; + + if (tas_data->state != SJA1105_TAS_STATE_RUNNING) + dev_err(ds->dev, "TAS surprisingly stopped\n"); + + break; + + default: + if (net_ratelimit()) + dev_err(ds->dev, "TAS in an invalid state (incorrect use of API)!\n"); + } + + if (rc && net_ratelimit()) + dev_err(ds->dev, "An operation returned %d\n", rc); + + mutex_unlock(&ptp_data->lock); +} + +void sja1105_tas_clockstep(struct dsa_switch *ds) +{ + struct sja1105_private *priv = ds->priv; + struct sja1105_tas_data *tas_data = &priv->tas_data; + + if (!tas_data->enabled) + return; + + tas_data->last_op = SJA1105_PTP_CLOCKSTEP; + schedule_work(&tas_data->tas_work); +} + +void sja1105_tas_adjfreq(struct dsa_switch *ds) +{ + struct sja1105_private *priv = ds->priv; + struct sja1105_tas_data *tas_data = &priv->tas_data; + + if (!tas_data->enabled) + return; + + /* No reason to schedule the workqueue, nothing changed */ + if (tas_data->state == SJA1105_TAS_STATE_RUNNING) + return; + + tas_data->last_op = SJA1105_PTP_ADJUSTFREQ; + schedule_work(&tas_data->tas_work); } void sja1105_tas_setup(struct dsa_switch *ds) { + struct sja1105_private *priv = ds->priv; + struct sja1105_tas_data *tas_data = &priv->tas_data; + + INIT_WORK(&tas_data->tas_work, sja1105_tas_state_machine); + tas_data->state = SJA1105_TAS_STATE_DISABLED; + tas_data->last_op = SJA1105_PTP_NONE; } void sja1105_tas_teardown(struct dsa_switch *ds) @@ -413,6 +819,8 @@ void sja1105_tas_teardown(struct dsa_switch *ds) struct tc_taprio_qopt_offload *offload; int port; + cancel_work_sync(&priv->tas_data.tas_work); + for (port = 0; port < SJA1105_NUM_PORTS; port++) { offload = priv->tas_data.offload[port]; if (!offload) |