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