drivers/platform/chrome/cros_ec_sensorhub_ring.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for Chrome OS EC Sensor hub FIFO.
   4  *
   5  * Copyright 2020 Google LLC
   6  */
   7
   8 #include <linux/delay.h>
   9 #include <linux/device.h>
  10 #include <linux/iio/iio.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_data/cros_ec_commands.h>
  14 #include <linux/platform_data/cros_ec_proto.h>
  15 #include <linux/platform_data/cros_ec_sensorhub.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/sort.h>
  18 #include <linux/slab.h>
  19
  20 #include "cros_ec_trace.h"
  21
  22 /* Precision of fixed point for the m values from the filter */
  23 #define M_PRECISION BIT(23)
  24
  25 /* Only activate the filter once we have at least this many elements. */
  26 #define TS_HISTORY_THRESHOLD 8
  27
  28 /*
  29  * If we don't have any history entries for this long, empty the filter to
  30  * make sure there are no big discontinuities.
  31  */
  32 #define TS_HISTORY_BORED_US 500000
  33
  34 /* To measure by how much the filter is overshooting, if it happens. */
  35 #define FUTURE_TS_ANALYTICS_COUNT_MAX 100
  36
  37 static inline int
  38 cros_sensorhub_send_sample(struct cros_ec_sensorhub *sensorhub,
  39                            struct cros_ec_sensors_ring_sample *sample)
  40 {
  41         cros_ec_sensorhub_push_data_cb_t cb;
  42         int id = sample->sensor_id;
  43         struct iio_dev *indio_dev;
  44
  45         if (id >= sensorhub->sensor_num)
  46                 return -EINVAL;
  47
  48         cb = sensorhub->push_data[id].push_data_cb;
  49         if (!cb)
  50                 return 0;
  51
  52         indio_dev = sensorhub->push_data[id].indio_dev;
  53
  54         if (sample->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH)
  55                 return 0;
  56
  57         return cb(indio_dev, sample->vector, sample->timestamp);
  58 }
  59
  60 /**
  61  * cros_ec_sensorhub_register_push_data() - register the callback to the hub.
  62  *
  63  * @sensorhub : Sensor Hub object
  64  * @sensor_num : The sensor the caller is interested in.
  65  * @indio_dev : The iio device to use when a sample arrives.
  66  * @cb : The callback to call when a sample arrives.
  67  *
  68  * The callback cb will be used by cros_ec_sensorhub_ring to distribute events
  69  * from the EC.
  70  *
  71  * Return: 0 when callback is registered.
  72  *         EINVAL is the sensor number is invalid or the slot already used.
  73  */
  74 int cros_ec_sensorhub_register_push_data(struct cros_ec_sensorhub *sensorhub,
  75                                          u8 sensor_num,
  76                                          struct iio_dev *indio_dev,
  77                                          cros_ec_sensorhub_push_data_cb_t cb)
  78 {
  79         if (sensor_num >= sensorhub->sensor_num)
  80                 return -EINVAL;
  81         if (sensorhub->push_data[sensor_num].indio_dev)
  82                 return -EINVAL;
  83
  84         sensorhub->push_data[sensor_num].indio_dev = indio_dev;
  85         sensorhub->push_data[sensor_num].push_data_cb = cb;
  86
  87         return 0;
  88 }
  89 EXPORT_SYMBOL_GPL(cros_ec_sensorhub_register_push_data);
  90
  91 void cros_ec_sensorhub_unregister_push_data(struct cros_ec_sensorhub *sensorhub,
  92                                             u8 sensor_num)
  93 {
  94         sensorhub->push_data[sensor_num].indio_dev = NULL;
  95         sensorhub->push_data[sensor_num].push_data_cb = NULL;
  96 }
  97 EXPORT_SYMBOL_GPL(cros_ec_sensorhub_unregister_push_data);
  98
  99 /**
 100  * cros_ec_sensorhub_ring_fifo_enable() - Enable or disable interrupt generation
 101  *                                        for FIFO events.
 102  * @sensorhub: Sensor Hub object
 103  * @on: true when events are requested.
 104  *
 105  * To be called before sleeping or when noone is listening.
 106  * Return: 0 on success, or an error when we can not communicate with the EC.
 107  *
 108  */
 109 int cros_ec_sensorhub_ring_fifo_enable(struct cros_ec_sensorhub *sensorhub,
 110                                        bool on)
 111 {
 112         int ret, i;
 113
 114         mutex_lock(&sensorhub->cmd_lock);
 115         if (sensorhub->tight_timestamps)
 116                 for (i = 0; i < sensorhub->sensor_num; i++)
 117                         sensorhub->batch_state[i].last_len = 0;
 118
 119         sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INT_ENABLE;
 120         sensorhub->params->fifo_int_enable.enable = on;
 121
 122         sensorhub->msg->outsize = sizeof(struct ec_params_motion_sense);
 123         sensorhub->msg->insize = sizeof(struct ec_response_motion_sense);
 124
 125         ret = cros_ec_cmd_xfer_status(sensorhub->ec->ec_dev, sensorhub->msg);
 126         mutex_unlock(&sensorhub->cmd_lock);
 127
 128         /* We expect to receive a payload of 4 bytes, ignore. */
 129         if (ret > 0)
 130                 ret = 0;
 131
 132         return ret;
 133 }
 134
 135 static int cros_ec_sensor_ring_median_cmp(const void *pv1, const void *pv2)
 136 {
 137         s64 v1 = *(s64 *)pv1;
 138         s64 v2 = *(s64 *)pv2;
 139
 140         if (v1 > v2)
 141                 return 1;
 142         else if (v1 < v2)
 143                 return -1;
 144         else
 145                 return 0;
 146 }
 147
 148 /*
 149  * cros_ec_sensor_ring_median: Gets median of an array of numbers
 150  *
 151  * For now it's implemented using an inefficient > O(n) sort then return
 152  * the middle element. A more optimal method would be something like
 153  * quickselect, but given that n = 64 we can probably live with it in the
 154  * name of clarity.
 155  *
 156  * Warning: the input array gets modified (sorted)!
 157  */
 158 static s64 cros_ec_sensor_ring_median(s64 *array, size_t length)
 159 {
 160         sort(array, length, sizeof(s64), cros_ec_sensor_ring_median_cmp, NULL);
 161         return array[length / 2];
 162 }
 163
 164 /*
 165  * IRQ Timestamp Filtering
 166  *
 167  * Lower down in cros_ec_sensor_ring_process_event(), for each sensor event
 168  * we have to calculate it's timestamp in the AP timebase. There are 3 time
 169  * points:
 170  *   a - EC timebase, sensor event
 171  *   b - EC timebase, IRQ
 172  *   c - AP timebase, IRQ
 173  *   a' - what we want: sensor even in AP timebase
 174  *
 175  * While a and b are recorded at accurate times (due to the EC real time
 176  * nature); c is pretty untrustworthy, even though it's recorded the
 177  * first thing in ec_irq_handler(). There is a very good change we'll get
 178  * added lantency due to:
 179  *   other irqs
 180  *   ddrfreq
 181  *   cpuidle
 182  *
 183  * Normally a' = c - b + a, but if we do that naive math any jitter in c
 184  * will get coupled in a', which we don't want. We want a function
 185  * a' = cros_ec_sensor_ring_ts_filter(a) which will filter out outliers in c.
 186  *
 187  * Think of a graph of AP time(b) on the y axis vs EC time(c) on the x axis.
 188  * The slope of the line won't be exactly 1, there will be some clock drift
 189  * between the 2 chips for various reasons (mechanical stress, temperature,
 190  * voltage). We need to extrapolate values for a future x, without trusting
 191  * recent y values too much.
 192  *
 193  * We use a median filter for the slope, then another median filter for the
 194  * y-intercept to calculate this function:
 195  *   dx[n] = x[n-1] - x[n]
 196  *   dy[n] = x[n-1] - x[n]
 197  *   m[n] = dy[n] / dx[n]
 198  *   median_m = median(m[n-k:n])
 199  *   error[i] = y[n-i] - median_m * x[n-i]
 200  *   median_error = median(error[:k])
 201  *   predicted_y = median_m * x + median_error
 202  *
 203  * Implementation differences from above:
 204  * - Redefined y to be actually c - b, this gives us a lot more precision
 205  * to do the math. (c-b)/b variations are more obvious than c/b variations.
 206  * - Since we don't have floating point, any operations involving slope are
 207  * done using fixed point math (*M_PRECISION)
 208  * - Since x and y grow with time, we keep zeroing the graph (relative to
 209  * the last sample), this way math involving *x[n-i] will not overflow
 210  * - EC timestamps are kept in us, it improves the slope calculation precision
 211  */
 212
 213 /**
 214  * cros_ec_sensor_ring_ts_filter_update() - Update filter history.
 215  *
 216  * @state: Filter information.
 217  * @b: IRQ timestamp, EC timebase (us)
 218  * @c: IRQ timestamp, AP timebase (ns)
 219  *
 220  * Given a new IRQ timestamp pair (EC and AP timebases), add it to the filter
 221  * history.
 222  */
 223 static void
 224 cros_ec_sensor_ring_ts_filter_update(struct cros_ec_sensors_ts_filter_state
 225                                      *state,
 226                                      s64 b, s64 c)
 227 {
 228         s64 x, y;
 229         s64 dx, dy;
 230         s64 m; /* stored as *M_PRECISION */
 231         s64 *m_history_copy = state->temp_buf;
 232         s64 *error = state->temp_buf;
 233         int i;
 234
 235         /* we trust b the most, that'll be our independent variable */
 236         x = b;
 237         /* y is the offset between AP and EC times, in ns */
 238         y = c - b * 1000;
 239
 240         dx = (state->x_history[0] + state->x_offset) - x;
 241         if (dx == 0)
 242                 return; /* we already have this irq in the history */
 243         dy = (state->y_history[0] + state->y_offset) - y;
 244         m = div64_s64(dy * M_PRECISION, dx);
 245
 246         /* Empty filter if we haven't seen any action in a while. */
 247         if (-dx > TS_HISTORY_BORED_US)
 248                 state->history_len = 0;
 249
 250         /* Move everything over, also update offset to all absolute coords .*/
 251         for (i = state->history_len - 1; i >= 1; i--) {
 252                 state->x_history[i] = state->x_history[i - 1] + dx;
 253                 state->y_history[i] = state->y_history[i - 1] + dy;
 254
 255                 state->m_history[i] = state->m_history[i - 1];
 256                 /*
 257                  * Also use the same loop to copy m_history for future
 258                  * median extraction.
 259                  */
 260                 m_history_copy[i] = state->m_history[i - 1];
 261         }
 262
 263         /* Store the x and y, but remember offset is actually last sample. */
 264         state->x_offset = x;
 265         state->y_offset = y;
 266         state->x_history[0] = 0;
 267         state->y_history[0] = 0;
 268
 269         state->m_history[0] = m;
 270         m_history_copy[0] = m;
 271
 272         if (state->history_len < CROS_EC_SENSORHUB_TS_HISTORY_SIZE)
 273                 state->history_len++;
 274
 275         /* Precalculate things for the filter. */
 276         if (state->history_len > TS_HISTORY_THRESHOLD) {
 277                 state->median_m =
 278                     cros_ec_sensor_ring_median(m_history_copy,
 279                                                state->history_len - 1);
 280
 281                 /*
 282                  * Calculate y-intercepts as if m_median is the slope and
 283                  * points in the history are on the line. median_error will
 284                  * still be in the offset coordinate system.
 285                  */
 286                 for (i = 0; i < state->history_len; i++)
 287                         error[i] = state->y_history[i] -
 288                                 div_s64(state->median_m * state->x_history[i],
 289                                         M_PRECISION);
 290                 state->median_error =
 291                         cros_ec_sensor_ring_median(error, state->history_len);
 292         } else {
 293                 state->median_m = 0;
 294                 state->median_error = 0;
 295         }
 296         trace_cros_ec_sensorhub_filter(state, dx, dy);
 297 }
 298
 299 /**
 300  * cros_ec_sensor_ring_ts_filter() - Translate EC timebase timestamp to AP
 301  *                                   timebase
 302  *
 303  * @state: filter information.
 304  * @x: any ec timestamp (us):
 305  *
 306  * cros_ec_sensor_ring_ts_filter(a) => a' event timestamp, AP timebase
 307  * cros_ec_sensor_ring_ts_filter(b) => calculated timestamp when the EC IRQ
 308  *                           should have happened on the AP, with low jitter
 309  *
 310  * Note: The filter will only activate once state->history_len goes
 311  * over TS_HISTORY_THRESHOLD. Otherwise it'll just do the naive c - b + a
 312  * transform.
 313  *
 314  * How to derive the formula, starting from:
 315  *   f(x) = median_m * x + median_error
 316  * That's the calculated AP - EC offset (at the x point in time)
 317  * Undo the coordinate system transform:
 318  *   f(x) = median_m * (x - x_offset) + median_error + y_offset
 319  * Remember to undo the "y = c - b * 1000" modification:
 320  *   f(x) = median_m * (x - x_offset) + median_error + y_offset + x * 1000
 321  *
 322  * Return: timestamp in AP timebase (ns)
 323  */
 324 static s64
 325 cros_ec_sensor_ring_ts_filter(struct cros_ec_sensors_ts_filter_state *state,
 326                               s64 x)
 327 {
 328         return div_s64(state->median_m * (x - state->x_offset), M_PRECISION)
 329                + state->median_error + state->y_offset + x * 1000;
 330 }
 331
 332 /*
 333  * Since a and b were originally 32 bit values from the EC,
 334  * they overflow relatively often, casting is not enough, so we need to
 335  * add an offset.
 336  */
 337 static void
 338 cros_ec_sensor_ring_fix_overflow(s64 *ts,
 339                                  const s64 overflow_period,
 340                                  struct cros_ec_sensors_ec_overflow_state
 341                                  *state)
 342 {
 343         s64 adjust;
 344
 345         *ts += state->offset;
 346         if (abs(state->last - *ts) > (overflow_period / 2)) {
 347                 adjust = state->last > *ts ? overflow_period : -overflow_period;
 348                 state->offset += adjust;
 349                 *ts += adjust;
 350         }
 351         state->last = *ts;
 352 }
 353
 354 static void
 355 cros_ec_sensor_ring_check_for_past_timestamp(struct cros_ec_sensorhub
 356                                              *sensorhub,
 357                                              struct cros_ec_sensors_ring_sample
 358                                              *sample)
 359 {
 360         const u8 sensor_id = sample->sensor_id;
 361
 362         /* If this event is earlier than one we saw before... */
 363         if (sensorhub->batch_state[sensor_id].newest_sensor_event >
 364             sample->timestamp)
 365                 /* mark it for spreading. */
 366                 sample->timestamp =
 367                         sensorhub->batch_state[sensor_id].last_ts;
 368         else
 369                 sensorhub->batch_state[sensor_id].newest_sensor_event =
 370                         sample->timestamp;
 371 }
 372
 373 /**
 374  * cros_ec_sensor_ring_process_event() - Process one EC FIFO event
 375  *
 376  * @sensorhub: Sensor Hub object.
 377  * @fifo_info: FIFO information from the EC (includes b point, EC timebase).
 378  * @fifo_timestamp: EC IRQ, kernel timebase (aka c).
 379  * @current_timestamp: calculated event timestamp, kernel timebase (aka a').
 380  * @in: incoming FIFO event from EC (includes a point, EC timebase).
 381  * @out: outgoing event to user space (includes a').
 382  *
 383  * Process one EC event, add it in the ring if necessary.
 384  *
 385  * Return: true if out event has been populated.
 386  */
 387 static bool
 388 cros_ec_sensor_ring_process_event(struct cros_ec_sensorhub *sensorhub,
 389                                 const struct ec_response_motion_sense_fifo_info
 390                                 *fifo_info,
 391                                 const ktime_t fifo_timestamp,
 392                                 ktime_t *current_timestamp,
 393                                 struct ec_response_motion_sensor_data *in,
 394                                 struct cros_ec_sensors_ring_sample *out)
 395 {
 396         const s64 now = cros_ec_get_time_ns();
 397         int axis, async_flags;
 398
 399         /* Do not populate the filter based on asynchronous events. */
 400         async_flags = in->flags &
 401                 (MOTIONSENSE_SENSOR_FLAG_ODR | MOTIONSENSE_SENSOR_FLAG_FLUSH);
 402
 403         if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP && !async_flags) {
 404                 s64 a = in->timestamp;
 405                 s64 b = fifo_info->timestamp;
 406                 s64 c = fifo_timestamp;
 407
 408                 cros_ec_sensor_ring_fix_overflow(&a, 1LL << 32,
 409                                           &sensorhub->overflow_a);
 410                 cros_ec_sensor_ring_fix_overflow(&b, 1LL << 32,
 411                                           &sensorhub->overflow_b);
 412
 413                 if (sensorhub->tight_timestamps) {
 414                         cros_ec_sensor_ring_ts_filter_update(
 415                                         &sensorhub->filter, b, c);
 416                         *current_timestamp = cros_ec_sensor_ring_ts_filter(
 417                                         &sensorhub->filter, a);
 418                 } else {
 419                         s64 new_timestamp;
 420
 421                         /*
 422                          * Disable filtering since we might add more jitter
 423                          * if b is in a random point in time.
 424                          */
 425                         new_timestamp = c - b * 1000 + a * 1000;
 426                         /*
 427                          * The timestamp can be stale if we had to use the fifo
 428                          * info timestamp.
 429                          */
 430                         if (new_timestamp - *current_timestamp > 0)
 431                                 *current_timestamp = new_timestamp;
 432                 }
 433                 trace_cros_ec_sensorhub_timestamp(in->timestamp,
 434                                                   fifo_info->timestamp,
 435                                                   fifo_timestamp,
 436                                                   *current_timestamp,
 437                                                   now);
 438         }
 439
 440         if (in->flags & MOTIONSENSE_SENSOR_FLAG_ODR) {
 441                 if (sensorhub->tight_timestamps) {
 442                         sensorhub->batch_state[in->sensor_num].last_len = 0;
 443                         sensorhub->batch_state[in->sensor_num].penul_len = 0;
 444                 }
 445                 /*
 446                  * ODR change is only useful for the sensor_ring, it does not
 447                  * convey information to clients.
 448                  */
 449                 return false;
 450         }
 451
 452         if (in->flags & MOTIONSENSE_SENSOR_FLAG_FLUSH) {
 453                 out->sensor_id = in->sensor_num;
 454                 out->timestamp = *current_timestamp;
 455                 out->flag = in->flags;
 456                 if (sensorhub->tight_timestamps)
 457                         sensorhub->batch_state[out->sensor_id].last_len = 0;
 458                 /*
 459                  * No other payload information provided with
 460                  * flush ack.
 461                  */
 462                 return true;
 463         }
 464
 465         if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP)
 466                 /* If we just have a timestamp, skip this entry. */
 467                 return false;
 468
 469         /* Regular sample */
 470         out->sensor_id = in->sensor_num;
 471         trace_cros_ec_sensorhub_data(in->sensor_num,
 472                                      fifo_info->timestamp,
 473                                      fifo_timestamp,
 474                                      *current_timestamp,
 475                                      now);
 476
 477         if (*current_timestamp - now > 0) {
 478                 /*
 479                  * This fix is needed to overcome the timestamp filter putting
 480                  * events in the future.
 481                  */
 482                 sensorhub->future_timestamp_total_ns +=
 483                         *current_timestamp - now;
 484                 if (++sensorhub->future_timestamp_count ==
 485                                 FUTURE_TS_ANALYTICS_COUNT_MAX) {
 486                         s64 avg = div_s64(sensorhub->future_timestamp_total_ns,
 487                                         sensorhub->future_timestamp_count);
 488                         dev_warn_ratelimited(sensorhub->dev,
 489                                              "100 timestamps in the future, %lldns shaved on average\n",
 490                                              avg);
 491                         sensorhub->future_timestamp_count = 0;
 492                         sensorhub->future_timestamp_total_ns = 0;
 493                 }
 494                 out->timestamp = now;
 495         } else {
 496                 out->timestamp = *current_timestamp;
 497         }
 498
 499         out->flag = in->flags;
 500         for (axis = 0; axis < 3; axis++)
 501                 out->vector[axis] = in->data[axis];
 502
 503         if (sensorhub->tight_timestamps)
 504                 cros_ec_sensor_ring_check_for_past_timestamp(sensorhub, out);
 505         return true;
 506 }
 507
 508 /*
 509  * cros_ec_sensor_ring_spread_add: Calculate proper timestamps then add to
 510  *                                 ringbuffer.
 511  *
 512  * This is the new spreading code, assumes every sample's timestamp
 513  * preceeds the sample. Run if tight_timestamps == true.
 514  *
 515  * Sometimes the EC receives only one interrupt (hence timestamp) for
 516  * a batch of samples. Only the first sample will have the correct
 517  * timestamp. So we must interpolate the other samples.
 518  * We use the previous batch timestamp and our current batch timestamp
 519  * as a way to calculate period, then spread the samples evenly.
 520  *
 521  * s0 int, 0ms
 522  * s1 int, 10ms
 523  * s2 int, 20ms
 524  * 30ms point goes by, no interrupt, previous one is still asserted
 525  * downloading s2 and s3
 526  * s3 sample, 20ms (incorrect timestamp)
 527  * s4 int, 40ms
 528  *
 529  * The batches are [(s0), (s1), (s2, s3), (s4)]. Since the 3rd batch
 530  * has 2 samples in them, we adjust the timestamp of s3.
 531  * s2 - s1 = 10ms, so s3 must be s2 + 10ms => 20ms. If s1 would have
 532  * been part of a bigger batch things would have gotten a little
 533  * more complicated.
 534  *
 535  * Note: we also assume another sensor sample doesn't break up a batch
 536  * in 2 or more partitions. Example, there can't ever be a sync sensor
 537  * in between S2 and S3. This simplifies the following code.
 538  */
 539 static void
 540 cros_ec_sensor_ring_spread_add(struct cros_ec_sensorhub *sensorhub,
 541                                unsigned long sensor_mask,
 542                                struct cros_ec_sensors_ring_sample *last_out)
 543 {
 544         struct cros_ec_sensors_ring_sample *batch_start, *next_batch_start;
 545         int id;
 546
 547         for_each_set_bit(id, &sensor_mask, sensorhub->sensor_num) {
 548                 for (batch_start = sensorhub->ring; batch_start < last_out;
 549                      batch_start = next_batch_start) {
 550                         /*
 551                          * For each batch (where all samples have the same
 552                          * timestamp).
 553                          */
 554                         int batch_len, sample_idx;
 555                         struct cros_ec_sensors_ring_sample *batch_end =
 556                                 batch_start;
 557                         struct cros_ec_sensors_ring_sample *s;
 558                         s64 batch_timestamp = batch_start->timestamp;
 559                         s64 sample_period;
 560
 561                         /*
 562                          * Skip over batches that start with the sensor types
 563                          * we're not looking at right now.
 564                          */
 565                         if (batch_start->sensor_id != id) {
 566                                 next_batch_start = batch_start + 1;
 567                                 continue;
 568                         }
 569
 570                         /*
 571                          * Do not start a batch
 572                          * from a flush, as it happens asynchronously to the
 573                          * regular flow of events.
 574                          */
 575                         if (batch_start->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH) {
 576                                 cros_sensorhub_send_sample(sensorhub,
 577                                                            batch_start);
 578                                 next_batch_start = batch_start + 1;
 579                                 continue;
 580                         }
 581
 582                         if (batch_start->timestamp <=
 583                             sensorhub->batch_state[id].last_ts) {
 584                                 batch_timestamp =
 585                                         sensorhub->batch_state[id].last_ts;
 586                                 batch_len = sensorhub->batch_state[id].last_len;
 587
 588                                 sample_idx = batch_len;
 589
 590                                 sensorhub->batch_state[id].last_ts =
 591                                   sensorhub->batch_state[id].penul_ts;
 592                                 sensorhub->batch_state[id].last_len =
 593                                   sensorhub->batch_state[id].penul_len;
 594                         } else {
 595                                 /*
 596                                  * Push first sample in the batch to the,
 597                                  * kifo, it's guaranteed to be correct, the
 598                                  * rest will follow later on.
 599                                  */
 600                                 sample_idx = 1;
 601                                 batch_len = 1;
 602                                 cros_sensorhub_send_sample(sensorhub,
 603                                                            batch_start);
 604                                 batch_start++;
 605                         }
 606
 607                         /* Find all samples have the same timestamp. */
 608                         for (s = batch_start; s < last_out; s++) {
 609                                 if (s->sensor_id != id)
 610                                         /*
 611                                          * Skip over other sensor types that
 612                                          * are interleaved, don't count them.
 613                                          */
 614                                         continue;
 615                                 if (s->timestamp != batch_timestamp)
 616                                         /* we discovered the next batch */
 617                                         break;
 618                                 if (s->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH)
 619                                         /* break on flush packets */
 620                                         break;
 621                                 batch_end = s;
 622                                 batch_len++;
 623                         }
 624
 625                         if (batch_len == 1)
 626                                 goto done_with_this_batch;
 627
 628                         /* Can we calculate period? */
 629                         if (sensorhub->batch_state[id].last_len == 0) {
 630                                 dev_warn(sensorhub->dev, "Sensor %d: lost %d samples when spreading\n",
 631                                          id, batch_len - 1);
 632                                 goto done_with_this_batch;
 633                                 /*
 634                                  * Note: we're dropping the rest of the samples
 635                                  * in this batch since we have no idea where
 636                                  * they're supposed to go without a period
 637                                  * calculation.
 638                                  */
 639                         }
 640
 641                         sample_period = div_s64(batch_timestamp -
 642                                 sensorhub->batch_state[id].last_ts,
 643                                 sensorhub->batch_state[id].last_len);
 644                         dev_dbg(sensorhub->dev,
 645                                 "Adjusting %d samples, sensor %d last_batch @%lld (%d samples) batch_timestamp=%lld => period=%lld\n",
 646                                 batch_len, id,
 647                                 sensorhub->batch_state[id].last_ts,
 648                                 sensorhub->batch_state[id].last_len,
 649                                 batch_timestamp,
 650                                 sample_period);
 651
 652                         /*
 653                          * Adjust timestamps of the samples then push them to
 654                          * kfifo.
 655                          */
 656                         for (s = batch_start; s <= batch_end; s++) {
 657                                 if (s->sensor_id != id)
 658                                         /*
 659                                          * Skip over other sensor types that
 660                                          * are interleaved, don't change them.
 661                                          */
 662                                         continue;
 663
 664                                 s->timestamp = batch_timestamp +
 665                                         sample_period * sample_idx;
 666                                 sample_idx++;
 667
 668                                 cros_sensorhub_send_sample(sensorhub, s);
 669                         }
 670
 671 done_with_this_batch:
 672                         sensorhub->batch_state[id].penul_ts =
 673                                 sensorhub->batch_state[id].last_ts;
 674                         sensorhub->batch_state[id].penul_len =
 675                                 sensorhub->batch_state[id].last_len;
 676
 677                         sensorhub->batch_state[id].last_ts =
 678                                 batch_timestamp;
 679                         sensorhub->batch_state[id].last_len = batch_len;
 680
 681                         next_batch_start = batch_end + 1;
 682                 }
 683         }
 684 }
 685
 686 /*
 687  * cros_ec_sensor_ring_spread_add_legacy: Calculate proper timestamps then
 688  * add to ringbuffer (legacy).
 689  *
 690  * Note: This assumes we're running old firmware, where timestamp
 691  * is inserted after its sample(s)e. There can be several samples between
 692  * timestamps, so several samples can have the same timestamp.
 693  *
 694  *                        timestamp | count
 695  *                        -----------------
 696  *          1st sample --> TS1      | 1
 697  *                         TS2      | 2
 698  *                         TS2      | 3
 699  *                         TS3      | 4
 700  *           last_out -->
 701  *
 702  *
 703  * We spread time for the samples using perod p = (current - TS1)/4.
 704  * between TS1 and TS2: [TS1+p/4, TS1+2p/4, TS1+3p/4, current_timestamp].
 705  *
 706  */
 707 static void
 708 cros_ec_sensor_ring_spread_add_legacy(struct cros_ec_sensorhub *sensorhub,
 709                                       unsigned long sensor_mask,
 710                                       s64 current_timestamp,
 711                                       struct cros_ec_sensors_ring_sample
 712                                       *last_out)
 713 {
 714         struct cros_ec_sensors_ring_sample *out;
 715         int i;
 716
 717         for_each_set_bit(i, &sensor_mask, sensorhub->sensor_num) {
 718                 s64 timestamp;
 719                 int count = 0;
 720                 s64 time_period;
 721
 722                 for (out = sensorhub->ring; out < last_out; out++) {
 723                         if (out->sensor_id != i)
 724                                 continue;
 725
 726                         /* Timestamp to start with */
 727                         timestamp = out->timestamp;
 728                         out++;
 729                         count = 1;
 730                         break;
 731                 }
 732                 for (; out < last_out; out++) {
 733                         /* Find last sample. */
 734                         if (out->sensor_id != i)
 735                                 continue;
 736                         count++;
 737                 }
 738                 if (count == 0)
 739                         continue;
 740
 741                 /* Spread uniformly between the first and last samples. */
 742                 time_period = div_s64(current_timestamp - timestamp, count);
 743
 744                 for (out = sensorhub->ring; out < last_out; out++) {
 745                         if (out->sensor_id != i)
 746                                 continue;
 747                         timestamp += time_period;
 748                         out->timestamp = timestamp;
 749                 }
 750         }
 751
 752         /* Push the event into the kfifo */
 753         for (out = sensorhub->ring; out < last_out; out++)
 754                 cros_sensorhub_send_sample(sensorhub, out);
 755 }
 756
 757 /**
 758  * cros_ec_sensorhub_ring_handler() - The trigger handler function
 759  *
 760  * @sensorhub: Sensor Hub object.
 761  *
 762  * Called by the notifier, process the EC sensor FIFO queue.
 763  */
 764 static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
 765 {
 766         struct ec_response_motion_sense_fifo_info *fifo_info =
 767                 sensorhub->fifo_info;
 768         struct cros_ec_dev *ec = sensorhub->ec;
 769         ktime_t fifo_timestamp, current_timestamp;
 770         int i, j, number_data, ret;
 771         unsigned long sensor_mask = 0;
 772         struct ec_response_motion_sensor_data *in;
 773         struct cros_ec_sensors_ring_sample *out, *last_out;
 774
 775         mutex_lock(&sensorhub->cmd_lock);
 776
 777         /* Get FIFO information if there are lost vectors. */
 778         if (fifo_info->total_lost) {
 779                 int fifo_info_length =
 780                         sizeof(struct ec_response_motion_sense_fifo_info) +
 781                         sizeof(u16) * sensorhub->sensor_num;
 782
 783                 /* Need to retrieve the number of lost vectors per sensor */
 784                 sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
 785                 sensorhub->msg->outsize = 1;
 786                 sensorhub->msg->insize = fifo_info_length;
 787
 788                 if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
 789                         goto error;
 790
 791                 memcpy(fifo_info, &sensorhub->resp->fifo_info,
 792                        fifo_info_length);
 793
 794                 /*
 795                  * Update collection time, will not be as precise as the
 796                  * non-error case.
 797                  */
 798                 fifo_timestamp = cros_ec_get_time_ns();
 799         } else {
 800                 fifo_timestamp = sensorhub->fifo_timestamp[
 801                         CROS_EC_SENSOR_NEW_TS];
 802         }
 803
 804         if (fifo_info->count > sensorhub->fifo_size ||
 805             fifo_info->size != sensorhub->fifo_size) {
 806                 dev_warn(sensorhub->dev,
 807                          "Mismatch EC data: count %d, size %d - expected %d\n",
 808                          fifo_info->count, fifo_info->size,
 809                          sensorhub->fifo_size);
 810                 goto error;
 811         }
 812
 813         /* Copy elements in the main fifo */
 814         current_timestamp = sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS];
 815         out = sensorhub->ring;
 816         for (i = 0; i < fifo_info->count; i += number_data) {
 817                 sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_READ;
 818                 sensorhub->params->fifo_read.max_data_vector =
 819                         fifo_info->count - i;
 820                 sensorhub->msg->outsize =
 821                         sizeof(struct ec_params_motion_sense);
 822                 sensorhub->msg->insize =
 823                         sizeof(sensorhub->resp->fifo_read) +
 824                         sensorhub->params->fifo_read.max_data_vector *
 825                           sizeof(struct ec_response_motion_sensor_data);
 826                 ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
 827                 if (ret < 0) {
 828                         dev_warn(sensorhub->dev, "Fifo error: %d\n", ret);
 829                         break;
 830                 }
 831                 number_data = sensorhub->resp->fifo_read.number_data;
 832                 if (number_data == 0) {
 833                         dev_dbg(sensorhub->dev, "Unexpected empty FIFO\n");
 834                         break;
 835                 }
 836                 if (number_data > fifo_info->count - i) {
 837                         dev_warn(sensorhub->dev,
 838                                  "Invalid EC data: too many entry received: %d, expected %d\n",
 839                                  number_data, fifo_info->count - i);
 840                         break;
 841                 }
 842                 if (out + number_data >
 843                     sensorhub->ring + fifo_info->count) {
 844                         dev_warn(sensorhub->dev,
 845                                  "Too many samples: %d (%zd data) to %d entries for expected %d entries\n",
 846                                  i, out - sensorhub->ring, i + number_data,
 847                                  fifo_info->count);
 848                         break;
 849                 }
 850
 851                 for (in = sensorhub->resp->fifo_read.data, j = 0;
 852                      j < number_data; j++, in++) {
 853                         if (cros_ec_sensor_ring_process_event(
 854                                                 sensorhub, fifo_info,
 855                                                 fifo_timestamp,
 856                                                 &current_timestamp,
 857                                                 in, out)) {
 858                                 sensor_mask |= BIT(in->sensor_num);
 859                                 out++;
 860                         }
 861                 }
 862         }
 863         mutex_unlock(&sensorhub->cmd_lock);
 864         last_out = out;
 865
 866         if (out == sensorhub->ring)
 867                 /* Unexpected empty FIFO. */
 868                 goto ring_handler_end;
 869
 870         /*
 871          * Check if current_timestamp is ahead of the last sample. Normally,
 872          * the EC appends a timestamp after the last sample, but if the AP
 873          * is slow to respond to the IRQ, the EC may have added new samples.
 874          * Use the FIFO info timestamp as last timestamp then.
 875          */
 876         if (!sensorhub->tight_timestamps &&
 877             (last_out - 1)->timestamp == current_timestamp)
 878                 current_timestamp = fifo_timestamp;
 879
 880         /* Warn on lost samples. */
 881         if (fifo_info->total_lost)
 882                 for (i = 0; i < sensorhub->sensor_num; i++) {
 883                         if (fifo_info->lost[i]) {
 884                                 dev_warn_ratelimited(sensorhub->dev,
 885                                                      "Sensor %d: lost: %d out of %d\n",
 886                                                      i, fifo_info->lost[i],
 887                                                      fifo_info->total_lost);
 888                                 if (sensorhub->tight_timestamps)
 889                                         sensorhub->batch_state[i].last_len = 0;
 890                         }
 891                 }
 892
 893         /*
 894          * Spread samples in case of batching, then add them to the
 895          * ringbuffer.
 896          */
 897         if (sensorhub->tight_timestamps)
 898                 cros_ec_sensor_ring_spread_add(sensorhub, sensor_mask,
 899                                                last_out);
 900         else
 901                 cros_ec_sensor_ring_spread_add_legacy(sensorhub, sensor_mask,
 902                                                       current_timestamp,
 903                                                       last_out);
 904
 905 ring_handler_end:
 906         sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] = current_timestamp;
 907         return;
 908
 909 error:
 910         mutex_unlock(&sensorhub->cmd_lock);
 911 }
 912
 913 static int cros_ec_sensorhub_event(struct notifier_block *nb,
 914                                    unsigned long queued_during_suspend,
 915                                    void *_notify)
 916 {
 917         struct cros_ec_sensorhub *sensorhub;
 918         struct cros_ec_device *ec_dev;
 919
 920         sensorhub = container_of(nb, struct cros_ec_sensorhub, notifier);
 921         ec_dev = sensorhub->ec->ec_dev;
 922
 923         if (ec_dev->event_data.event_type != EC_MKBP_EVENT_SENSOR_FIFO)
 924                 return NOTIFY_DONE;
 925
 926         if (ec_dev->event_size != sizeof(ec_dev->event_data.data.sensor_fifo)) {
 927                 dev_warn(ec_dev->dev, "Invalid fifo info size\n");
 928                 return NOTIFY_DONE;
 929         }
 930
 931         if (queued_during_suspend)
 932                 return NOTIFY_OK;
 933
 934         memcpy(sensorhub->fifo_info, &ec_dev->event_data.data.sensor_fifo.info,
 935                sizeof(*sensorhub->fifo_info));
 936         sensorhub->fifo_timestamp[CROS_EC_SENSOR_NEW_TS] =
 937                 ec_dev->last_event_time;
 938         cros_ec_sensorhub_ring_handler(sensorhub);
 939
 940         return NOTIFY_OK;
 941 }
 942
 943 /**
 944  * cros_ec_sensorhub_ring_allocate() - Prepare the FIFO functionality if the EC
 945  *                                     supports it.
 946  *
 947  * @sensorhub : Sensor Hub object.
 948  *
 949  * Return: 0 on success.
 950  */
 951 int cros_ec_sensorhub_ring_allocate(struct cros_ec_sensorhub *sensorhub)
 952 {
 953         int fifo_info_length =
 954                 sizeof(struct ec_response_motion_sense_fifo_info) +
 955                 sizeof(u16) * sensorhub->sensor_num;
 956
 957         /* Allocate the array for lost events. */
 958         sensorhub->fifo_info = devm_kzalloc(sensorhub->dev, fifo_info_length,
 959                                             GFP_KERNEL);
 960         if (!sensorhub->fifo_info)
 961                 return -ENOMEM;
 962
 963         /*
 964          * Allocate the callback area based on the number of sensors.
 965          * Add one for the sensor ring.
 966          */
 967         sensorhub->push_data = devm_kcalloc(sensorhub->dev,
 968                         sensorhub->sensor_num,
 969                         sizeof(*sensorhub->push_data),
 970                         GFP_KERNEL);
 971         if (!sensorhub->push_data)
 972                 return -ENOMEM;
 973
 974         sensorhub->tight_timestamps = cros_ec_check_features(
 975                         sensorhub->ec,
 976                         EC_FEATURE_MOTION_SENSE_TIGHT_TIMESTAMPS);
 977
 978         if (sensorhub->tight_timestamps) {
 979                 sensorhub->batch_state = devm_kcalloc(sensorhub->dev,
 980                                 sensorhub->sensor_num,
 981                                 sizeof(*sensorhub->batch_state),
 982                                 GFP_KERNEL);
 983                 if (!sensorhub->batch_state)
 984                         return -ENOMEM;
 985         }
 986
 987         return 0;
 988 }
 989
 990 /**
 991  * cros_ec_sensorhub_ring_add() - Add the FIFO functionality if the EC
 992  *                                supports it.
 993  *
 994  * @sensorhub : Sensor Hub object.
 995  *
 996  * Return: 0 on success.
 997  */
 998 int cros_ec_sensorhub_ring_add(struct cros_ec_sensorhub *sensorhub)
 999 {
1000         struct cros_ec_dev *ec = sensorhub->ec;
1001         int ret;
1002         int fifo_info_length =
1003                 sizeof(struct ec_response_motion_sense_fifo_info) +
1004                 sizeof(u16) * sensorhub->sensor_num;
1005
1006         /* Retrieve FIFO information */
1007         sensorhub->msg->version = 2;
1008         sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
1009         sensorhub->msg->outsize = 1;
1010         sensorhub->msg->insize = fifo_info_length;
1011
1012         ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
1013         if (ret < 0)
1014                 return ret;
1015
1016         /*
1017          * Allocate the full fifo. We need to copy the whole FIFO to set
1018          * timestamps properly.
1019          */
1020         sensorhub->fifo_size = sensorhub->resp->fifo_info.size;
1021         sensorhub->ring = devm_kcalloc(sensorhub->dev, sensorhub->fifo_size,
1022                                        sizeof(*sensorhub->ring), GFP_KERNEL);
1023         if (!sensorhub->ring)
1024                 return -ENOMEM;
1025
1026         sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] =
1027                 cros_ec_get_time_ns();
1028
1029         /* Register the notifier that will act as a top half interrupt. */
1030         sensorhub->notifier.notifier_call = cros_ec_sensorhub_event;
1031         ret = blocking_notifier_chain_register(&ec->ec_dev->event_notifier,
1032                                                &sensorhub->notifier);
1033         if (ret < 0)
1034                 return ret;
1035
1036         /* Start collection samples. */
1037         return cros_ec_sensorhub_ring_fifo_enable(sensorhub, true);
1038 }
1039
1040 void cros_ec_sensorhub_ring_remove(void *arg)
1041 {
1042         struct cros_ec_sensorhub *sensorhub = arg;
1043         struct cros_ec_device *ec_dev = sensorhub->ec->ec_dev;
1044
1045         /* Disable the ring, prevent EC interrupt to the AP for nothing. */
1046         cros_ec_sensorhub_ring_fifo_enable(sensorhub, false);
1047         blocking_notifier_chain_unregister(&ec_dev->event_notifier,
1048                                            &sensorhub->notifier);
1049 }