diff options
Diffstat (limited to 'drivers/net/dsa/sja1105/sja1105_tas.c')
| -rw-r--r-- | drivers/net/dsa/sja1105/sja1105_tas.c | 900 |
1 files changed, 900 insertions, 0 deletions
diff --git a/drivers/net/dsa/sja1105/sja1105_tas.c b/drivers/net/dsa/sja1105/sja1105_tas.c new file mode 100644 index 0000000000..d7818710bc --- /dev/null +++ b/drivers/net/dsa/sja1105/sja1105_tas.c @@ -0,0 +1,900 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com> + */ +#include "sja1105.h" + +#define SJA1105_TAS_CLKSRC_DISABLED 0 +#define SJA1105_TAS_CLKSRC_STANDALONE 1 +#define SJA1105_TAS_CLKSRC_AS6802 2 +#define SJA1105_TAS_CLKSRC_PTP 3 +#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) + +static int sja1105_tas_set_runtime_params(struct sja1105_private *priv) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct sja1105_gating_config *gating_cfg = &tas_data->gating_cfg; + 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 < ds->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 (!list_empty(&gating_cfg->entries)) { + tas_data->enabled = true; + + if (max_cycle_time < gating_cfg->cycle_time) + max_cycle_time = gating_cfg->cycle_time; + if (latest_base_time < gating_cfg->base_time) + latest_base_time = gating_cfg->base_time; + if (earliest_base_time > gating_cfg->base_time) { + earliest_base_time = gating_cfg->base_time; + its_cycle_time = gating_cfg->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 + * all schedule entries for all ports. These are the Gate Control List (GCL) + * entries, let's call them "timeslots" for short. This linear array of + * timeslots is held in BLK_IDX_SCHEDULE. + * + * Then there are a maximum of 8 "execution threads" inside the switch, which + * iterate cyclically through the "schedule". Each "cycle" has an entry point + * and an exit point, both being timeslot indices in the schedule table. The + * hardware calls each cycle a "subschedule". + * + * Subschedule (cycle) i starts when + * ptpclkval >= ptpschtm + BLK_IDX_SCHEDULE_ENTRY_POINTS[i].delta. + * + * The hardware scheduler iterates BLK_IDX_SCHEDULE with a k ranging from + * k = BLK_IDX_SCHEDULE_ENTRY_POINTS[i].address to + * k = BLK_IDX_SCHEDULE_PARAMS.subscheind[i] + * + * For each schedule entry (timeslot) k, the engine executes the gate control + * list entry for the duration of BLK_IDX_SCHEDULE[k].delta. + * + * +---------+ + * | | BLK_IDX_SCHEDULE_ENTRY_POINTS_PARAMS + * +---------+ + * | + * +-----------------+ + * | .actsubsch + * BLK_IDX_SCHEDULE_ENTRY_POINTS v + * +-------+-------+ + * |cycle 0|cycle 1| + * +-------+-------+ + * | | | | + * +----------------+ | | +-------------------------------------+ + * | .subschindx | | .subschindx | + * | | +---------------+ | + * | .address | .address | | + * | | | | + * | | | | + * | BLK_IDX_SCHEDULE v v | + * | +-------+-------+-------+-------+-------+------+ | + * | |entry 0|entry 1|entry 2|entry 3|entry 4|entry5| | + * | +-------+-------+-------+-------+-------+------+ | + * | ^ ^ ^ ^ | + * | | | | | | + * | +-------------------------+ | | | | + * | | +-------------------------------+ | | | + * | | | +-------------------+ | | + * | | | | | | + * | +---------------------------------------------------------------+ | + * | |subscheind[0]<=subscheind[1]<=subscheind[2]<=...<=subscheind[7]| | + * | +---------------------------------------------------------------+ | + * | ^ ^ BLK_IDX_SCHEDULE_PARAMS | + * | | | | + * +--------+ +-------------------------------------------+ + * + * In the above picture there are two subschedules (cycles): + * + * - cycle 0: iterates the schedule table from 0 to 2 (and back) + * - cycle 1: iterates the schedule table from 3 to 5 (and back) + * + * All other possible execution threads must be marked as unused by making + * their "subschedule end index" (subscheind) equal to the last valid + * subschedule's end index (in this case 5). + */ +int sja1105_init_scheduling(struct sja1105_private *priv) +{ + struct sja1105_schedule_entry_points_entry *schedule_entry_points; + struct sja1105_schedule_entry_points_params_entry + *schedule_entry_points_params; + struct sja1105_schedule_params_entry *schedule_params; + struct sja1105_tas_data *tas_data = &priv->tas_data; + struct sja1105_gating_config *gating_cfg = &tas_data->gating_cfg; + struct sja1105_schedule_entry *schedule; + struct dsa_switch *ds = priv->ds; + struct sja1105_table *table; + int schedule_start_idx; + s64 entry_point_delta; + int schedule_end_idx; + int num_entries = 0; + int num_cycles = 0; + int cycle = 0; + int i, k = 0; + 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]; + if (table->entry_count) { + kfree(table->entries); + table->entry_count = 0; + } + + /* Discard previous Schedule Entry Points Parameters Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_ENTRY_POINTS_PARAMS]; + if (table->entry_count) { + kfree(table->entries); + table->entry_count = 0; + } + + /* Discard previous Schedule Parameters Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_PARAMS]; + if (table->entry_count) { + kfree(table->entries); + table->entry_count = 0; + } + + /* Discard previous Schedule Entry Points Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_ENTRY_POINTS]; + if (table->entry_count) { + kfree(table->entries); + table->entry_count = 0; + } + + /* Figure out the dimensioning of the problem */ + for (port = 0; port < ds->num_ports; port++) { + if (tas_data->offload[port]) { + num_entries += tas_data->offload[port]->num_entries; + num_cycles++; + } + } + + if (!list_empty(&gating_cfg->entries)) { + num_entries += gating_cfg->num_entries; + num_cycles++; + } + + /* Nothing to do */ + if (!num_cycles) + return 0; + + /* Pre-allocate space in the static config tables */ + + /* Schedule Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE]; + table->entries = kcalloc(num_entries, table->ops->unpacked_entry_size, + GFP_KERNEL); + if (!table->entries) + return -ENOMEM; + table->entry_count = num_entries; + schedule = table->entries; + + /* Schedule Points Parameters Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_ENTRY_POINTS_PARAMS]; + table->entries = kcalloc(SJA1105_MAX_SCHEDULE_ENTRY_POINTS_PARAMS_COUNT, + table->ops->unpacked_entry_size, GFP_KERNEL); + if (!table->entries) + /* Previously allocated memory will be freed automatically in + * sja1105_static_config_free. This is true for all early + * returns below. + */ + return -ENOMEM; + table->entry_count = SJA1105_MAX_SCHEDULE_ENTRY_POINTS_PARAMS_COUNT; + schedule_entry_points_params = table->entries; + + /* Schedule Parameters Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_PARAMS]; + table->entries = kcalloc(SJA1105_MAX_SCHEDULE_PARAMS_COUNT, + table->ops->unpacked_entry_size, GFP_KERNEL); + if (!table->entries) + return -ENOMEM; + table->entry_count = SJA1105_MAX_SCHEDULE_PARAMS_COUNT; + schedule_params = table->entries; + + /* Schedule Entry Points Table */ + table = &priv->static_config.tables[BLK_IDX_SCHEDULE_ENTRY_POINTS]; + table->entries = kcalloc(num_cycles, table->ops->unpacked_entry_size, + GFP_KERNEL); + if (!table->entries) + return -ENOMEM; + table->entry_count = num_cycles; + schedule_entry_points = table->entries; + + /* Finally start populating the static config tables */ + schedule_entry_points_params->clksrc = SJA1105_TAS_CLKSRC_PTP; + schedule_entry_points_params->actsubsch = num_cycles - 1; + + for (port = 0; port < ds->num_ports; port++) { + const struct tc_taprio_qopt_offload *offload; + /* Relative base time */ + s64 rbt; + + offload = tas_data->offload[port]; + if (!offload) + continue; + + schedule_start_idx = k; + schedule_end_idx = k + offload->num_entries - 1; + /* 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 = ns_to_sja1105_delta(rbt) + 1; + + schedule_entry_points[cycle].subschindx = cycle; + schedule_entry_points[cycle].delta = entry_point_delta; + schedule_entry_points[cycle].address = schedule_start_idx; + + /* The subschedule end indices need to be + * monotonically increasing. + */ + for (i = cycle; i < 8; i++) + schedule_params->subscheind[i] = schedule_end_idx; + + for (i = 0; i < offload->num_entries; i++, k++) { + s64 delta_ns = offload->entries[i].interval; + + schedule[k].delta = ns_to_sja1105_delta(delta_ns); + schedule[k].destports = BIT(port); + schedule[k].resmedia_en = true; + schedule[k].resmedia = SJA1105_GATE_MASK & + ~offload->entries[i].gate_mask; + } + cycle++; + } + + if (!list_empty(&gating_cfg->entries)) { + struct sja1105_gate_entry *e; + + /* Relative base time */ + s64 rbt; + + schedule_start_idx = k; + schedule_end_idx = k + gating_cfg->num_entries - 1; + rbt = future_base_time(gating_cfg->base_time, + gating_cfg->cycle_time, + tas_data->earliest_base_time); + rbt -= tas_data->earliest_base_time; + entry_point_delta = ns_to_sja1105_delta(rbt) + 1; + + schedule_entry_points[cycle].subschindx = cycle; + schedule_entry_points[cycle].delta = entry_point_delta; + schedule_entry_points[cycle].address = schedule_start_idx; + + for (i = cycle; i < 8; i++) + schedule_params->subscheind[i] = schedule_end_idx; + + list_for_each_entry(e, &gating_cfg->entries, list) { + schedule[k].delta = ns_to_sja1105_delta(e->interval); + schedule[k].destports = e->rule->vl.destports; + schedule[k].setvalid = true; + schedule[k].txen = true; + schedule[k].vlindex = e->rule->vl.sharindx; + schedule[k].winstindex = e->rule->vl.sharindx; + if (e->gate_state) /* Gate open */ + schedule[k].winst = true; + else /* Gate closed */ + schedule[k].winend = true; + k++; + } + } + + return 0; +} + +/* Be there 2 port subschedules, each executing an arbitrary number of gate + * open/close events cyclically. + * None of those gate events must ever occur at the exact same time, otherwise + * the switch is known to act in exotically strange ways. + * However the hardware doesn't bother performing these integrity checks. + * So here we are with the task of validating whether the new @admin offload + * has any conflict with the already established TAS configuration in + * tas_data->offload. We already know the other ports are in harmony with one + * another, otherwise we wouldn't have saved them. + * Each gate event executes periodically, with a period of @cycle_time and a + * phase given by its cycle's @base_time plus its offset within the cycle + * (which in turn is given by the length of the events prior to it). + * There are two aspects to possible collisions: + * - Collisions within one cycle's (actually the longest cycle's) time frame. + * For that, we need to compare the cartesian product of each possible + * occurrence of each event within one cycle time. + * - Collisions in the future. Events may not collide within one cycle time, + * but if two port schedules don't have the same periodicity (aka the cycle + * times aren't multiples of one another), they surely will some time in the + * future (actually they will collide an infinite amount of times). + */ +static bool +sja1105_tas_check_conflicts(struct sja1105_private *priv, int port, + const struct tc_taprio_qopt_offload *admin) +{ + struct sja1105_tas_data *tas_data = &priv->tas_data; + const struct tc_taprio_qopt_offload *offload; + s64 max_cycle_time, min_cycle_time; + s64 delta1, delta2; + s64 rbt1, rbt2; + s64 stop_time; + s64 t1, t2; + int i, j; + s32 rem; + + offload = tas_data->offload[port]; + if (!offload) + return false; + + /* Check if the two cycle times are multiples of one another. + * If they aren't, then they will surely collide. + */ + max_cycle_time = max(offload->cycle_time, admin->cycle_time); + min_cycle_time = min(offload->cycle_time, admin->cycle_time); + div_s64_rem(max_cycle_time, min_cycle_time, &rem); + if (rem) + return true; + + /* Calculate the "reduced" base time of each of the two cycles + * (transposed back as close to 0 as possible) by dividing to + * the cycle time. + */ + div_s64_rem(offload->base_time, offload->cycle_time, &rem); + rbt1 = rem; + + div_s64_rem(admin->base_time, admin->cycle_time, &rem); + rbt2 = rem; + + stop_time = max_cycle_time + max(rbt1, rbt2); + + /* delta1 is the relative base time of each GCL entry within + * the established ports' TAS config. + */ + for (i = 0, delta1 = 0; + i < offload->num_entries; + delta1 += offload->entries[i].interval, i++) { + /* delta2 is the relative base time of each GCL entry + * within the newly added TAS config. + */ + for (j = 0, delta2 = 0; + j < admin->num_entries; + delta2 += admin->entries[j].interval, j++) { + /* t1 follows all possible occurrences of the + * established ports' GCL entry i within the + * first cycle time. + */ + for (t1 = rbt1 + delta1; + t1 <= stop_time; + t1 += offload->cycle_time) { + /* t2 follows all possible occurrences + * of the newly added GCL entry j + * within the first cycle time. + */ + for (t2 = rbt2 + delta2; + t2 <= stop_time; + t2 += admin->cycle_time) { + if (t1 == t2) { + dev_warn(priv->ds->dev, + "GCL entry %d collides with entry %d of port %d\n", + j, i, port); + return true; + } + } + } + } + } + + return false; +} + +/* Check the tc-taprio configuration on @port for conflicts with the tc-gate + * global subschedule. If @port is -1, check it against all ports. + * To reuse the sja1105_tas_check_conflicts logic without refactoring it, + * convert the gating configuration to a dummy tc-taprio offload structure. + */ +bool sja1105_gating_check_conflicts(struct sja1105_private *priv, int port, + struct netlink_ext_ack *extack) +{ + struct sja1105_gating_config *gating_cfg = &priv->tas_data.gating_cfg; + size_t num_entries = gating_cfg->num_entries; + struct tc_taprio_qopt_offload *dummy; + struct dsa_switch *ds = priv->ds; + struct sja1105_gate_entry *e; + bool conflict; + int i = 0; + + if (list_empty(&gating_cfg->entries)) + return false; + + dummy = kzalloc(struct_size(dummy, entries, num_entries), GFP_KERNEL); + if (!dummy) { + NL_SET_ERR_MSG_MOD(extack, "Failed to allocate memory"); + return true; + } + + dummy->num_entries = num_entries; + dummy->base_time = gating_cfg->base_time; + dummy->cycle_time = gating_cfg->cycle_time; + + list_for_each_entry(e, &gating_cfg->entries, list) + dummy->entries[i++].interval = e->interval; + + if (port != -1) { + conflict = sja1105_tas_check_conflicts(priv, port, dummy); + } else { + for (port = 0; port < ds->num_ports; port++) { + conflict = sja1105_tas_check_conflicts(priv, port, + dummy); + if (conflict) + break; + } + } + + kfree(dummy); + + return conflict; +} + +int sja1105_setup_tc_taprio(struct dsa_switch *ds, int port, + struct tc_taprio_qopt_offload *admin) +{ + struct sja1105_private *priv = ds->priv; + struct sja1105_tas_data *tas_data = &priv->tas_data; + int other_port, rc, i; + + /* Can't change an already configured port (must delete qdisc first). + * Can't delete the qdisc from an unconfigured port. + */ + if ((!!tas_data->offload[port] && admin->cmd == TAPRIO_CMD_REPLACE) || + (!tas_data->offload[port] && admin->cmd == TAPRIO_CMD_DESTROY)) + return -EINVAL; + + if (admin->cmd == TAPRIO_CMD_DESTROY) { + taprio_offload_free(tas_data->offload[port]); + tas_data->offload[port] = NULL; + + rc = sja1105_init_scheduling(priv); + if (rc < 0) + return rc; + + return sja1105_static_config_reload(priv, SJA1105_SCHEDULING); + } else if (admin->cmd != TAPRIO_CMD_REPLACE) { + return -EOPNOTSUPP; + } + + /* The cycle time extension is the amount of time the last cycle from + * the old OPER needs to be extended in order to phase-align with the + * base time of the ADMIN when that becomes the new OPER. + * But of course our switch needs to be reset to switch-over between + * the ADMIN and the OPER configs - so much for a seamless transition. + * So don't add insult over injury and just say we don't support cycle + * time extension. + */ + if (admin->cycle_time_extension) + return -ENOTSUPP; + + for (i = 0; i < admin->num_entries; i++) { + s64 delta_ns = admin->entries[i].interval; + s64 delta_cycles = ns_to_sja1105_delta(delta_ns); + bool too_long, too_short; + + too_long = (delta_cycles >= SJA1105_TAS_MAX_DELTA); + too_short = (delta_cycles == 0); + if (too_long || too_short) { + dev_err(priv->ds->dev, + "Interval %llu too %s for GCL entry %d\n", + delta_ns, too_long ? "long" : "short", i); + return -ERANGE; + } + } + + for (other_port = 0; other_port < ds->num_ports; other_port++) { + if (other_port == port) + continue; + + if (sja1105_tas_check_conflicts(priv, other_port, admin)) + return -ERANGE; + } + + if (sja1105_gating_check_conflicts(priv, port, NULL)) { + dev_err(ds->dev, "Conflict with tc-gate schedule\n"); + return -ERANGE; + } + + tas_data->offload[port] = taprio_offload_get(admin); + + rc = sja1105_init_scheduling(priv); + if (rc < 0) + return rc; + + 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; + + INIT_LIST_HEAD(&tas_data->gating_cfg.entries); +} + +void sja1105_tas_teardown(struct dsa_switch *ds) +{ + struct sja1105_private *priv = ds->priv; + struct tc_taprio_qopt_offload *offload; + int port; + + cancel_work_sync(&priv->tas_data.tas_work); + + for (port = 0; port < ds->num_ports; port++) { + offload = priv->tas_data.offload[port]; + if (!offload) + continue; + + taprio_offload_free(offload); + } +} |