--- /dev/null
+// 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_TAS_MAX_DELTA BIT(19)
+#define SJA1105_GATE_MASK GENMASK_ULL(SJA1105_NUM_TC - 1, 0)
+
+/* 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.
+ */
+static s64 ns_to_sja1105_delta(s64 ns)
+{
+ return div_s64(ns, 200);
+}
+
+/* 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).
+ */
+static 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_schedule_entry *schedule;
+ 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;
+
+ /* 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 < SJA1105_NUM_PORTS; port++) {
+ if (tas_data->offload[port]) {
+ num_entries += tas_data->offload[port]->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_STANDALONE;
+ schedule_entry_points_params->actsubsch = num_cycles - 1;
+
+ for (port = 0; port < SJA1105_NUM_PORTS; port++) {
+ const struct tc_taprio_qopt_offload *offload;
+
+ offload = tas_data->offload[port];
+ if (!offload)
+ continue;
+
+ 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.
+ */
+ entry_point_delta = 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++;
+ }
+
+ 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;
+}
+
+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->enable)
+ return -EINVAL;
+
+ if (!admin->enable) {
+ 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);
+ }
+
+ /* 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;
+
+ if (!ns_to_sja1105_delta(admin->base_time)) {
+ dev_err(ds->dev, "A base time of zero is not hardware-allowed\n");
+ return -ERANGE;
+ }
+
+ 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 < SJA1105_NUM_PORTS; other_port++) {
+ if (other_port == port)
+ continue;
+
+ if (sja1105_tas_check_conflicts(priv, other_port, admin))
+ 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);
+}
+
+void sja1105_tas_setup(struct dsa_switch *ds)
+{
+}
+
+void sja1105_tas_teardown(struct dsa_switch *ds)
+{
+ struct sja1105_private *priv = ds->priv;
+ struct tc_taprio_qopt_offload *offload;
+ int port;
+
+ for (port = 0; port < SJA1105_NUM_PORTS; port++) {
+ offload = priv->tas_data.offload[port];
+ if (!offload)
+ continue;
+
+ taprio_offload_free(offload);
+ }
+}
projects / linux-2.6-microblaze.git / commitdiff