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#define CREATE_TRACE_POINTS
  21#include "cros_ec_sensorhub_trace.h"
  22
  23/* Precision of fixed point for the m values from the filter */
  24#define M_PRECISION BIT(23)
  25
  26/* Only activate the filter once we have at least this many elements. */
  27#define TS_HISTORY_THRESHOLD 8
  28
  29/*
  30 * If we don't have any history entries for this long, empty the filter to
  31 * make sure there are no big discontinuities.
  32 */
  33#define TS_HISTORY_BORED_US 500000
  34
  35/* To measure by how much the filter is overshooting, if it happens. */
  36#define FUTURE_TS_ANALYTICS_COUNT_MAX 100
  37
  38static inline int
  39cros_sensorhub_send_sample(struct cros_ec_sensorhub *sensorhub,
  40			   struct cros_ec_sensors_ring_sample *sample)
  41{
  42	cros_ec_sensorhub_push_data_cb_t cb;
  43	int id = sample->sensor_id;
  44	struct iio_dev *indio_dev;
  45
  46	if (id >= sensorhub->sensor_num)
  47		return -EINVAL;
  48
  49	cb = sensorhub->push_data[id].push_data_cb;
  50	if (!cb)
  51		return 0;
  52
  53	indio_dev = sensorhub->push_data[id].indio_dev;
  54
  55	if (sample->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH)
  56		return 0;
  57
  58	return cb(indio_dev, sample->vector, sample->timestamp);
  59}
  60
  61/**
  62 * cros_ec_sensorhub_register_push_data() - register the callback to the hub.
  63 *
  64 * @sensorhub : Sensor Hub object
  65 * @sensor_num : The sensor the caller is interested in.
  66 * @indio_dev : The iio device to use when a sample arrives.
  67 * @cb : The callback to call when a sample arrives.
  68 *
  69 * The callback cb will be used by cros_ec_sensorhub_ring to distribute events
  70 * from the EC.
  71 *
  72 * Return: 0 when callback is registered.
  73 *         EINVAL is the sensor number is invalid or the slot already used.
  74 */
  75int cros_ec_sensorhub_register_push_data(struct cros_ec_sensorhub *sensorhub,
  76					 u8 sensor_num,
  77					 struct iio_dev *indio_dev,
  78					 cros_ec_sensorhub_push_data_cb_t cb)
  79{
  80	if (sensor_num >= sensorhub->sensor_num)
  81		return -EINVAL;
  82	if (sensorhub->push_data[sensor_num].indio_dev)
  83		return -EINVAL;
  84
  85	sensorhub->push_data[sensor_num].indio_dev = indio_dev;
  86	sensorhub->push_data[sensor_num].push_data_cb = cb;
  87
  88	return 0;
  89}
  90EXPORT_SYMBOL_GPL(cros_ec_sensorhub_register_push_data);
  91
  92void cros_ec_sensorhub_unregister_push_data(struct cros_ec_sensorhub *sensorhub,
  93					    u8 sensor_num)
  94{
  95	sensorhub->push_data[sensor_num].indio_dev = NULL;
  96	sensorhub->push_data[sensor_num].push_data_cb = NULL;
  97}
  98EXPORT_SYMBOL_GPL(cros_ec_sensorhub_unregister_push_data);
  99
 100/**
 101 * cros_ec_sensorhub_ring_fifo_enable() - Enable or disable interrupt generation
 102 *					  for FIFO events.
 103 * @sensorhub: Sensor Hub object
 104 * @on: true when events are requested.
 105 *
 106 * To be called before sleeping or when no one is listening.
 107 * Return: 0 on success, or an error when we can not communicate with the EC.
 108 *
 109 */
 110int cros_ec_sensorhub_ring_fifo_enable(struct cros_ec_sensorhub *sensorhub,
 111				       bool on)
 112{
 113	int ret, i;
 114
 115	mutex_lock(&sensorhub->cmd_lock);
 116	if (sensorhub->tight_timestamps)
 117		for (i = 0; i < sensorhub->sensor_num; i++)
 118			sensorhub->batch_state[i].last_len = 0;
 119
 120	sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INT_ENABLE;
 121	sensorhub->params->fifo_int_enable.enable = on;
 122
 123	sensorhub->msg->outsize = sizeof(struct ec_params_motion_sense);
 124	sensorhub->msg->insize = sizeof(struct ec_response_motion_sense);
 125
 126	ret = cros_ec_cmd_xfer_status(sensorhub->ec->ec_dev, sensorhub->msg);
 127	mutex_unlock(&sensorhub->cmd_lock);
 128
 129	/* We expect to receive a payload of 4 bytes, ignore. */
 130	if (ret > 0)
 131		ret = 0;
 132
 133	return ret;
 134}
 135
 136static void cros_ec_sensor_ring_median_swap(s64 *a, s64 *b)
 137{
 138	s64 tmp = *a;
 139	*a = *b;
 140	*b = tmp;
 
 
 
 
 
 
 141}
 142
 143/*
 144 * cros_ec_sensor_ring_median: Gets median of an array of numbers
 145 *
 146 * It's implemented using the quickselect algorithm, which achieves an
 147 * average time complexity of O(n) the middle element. In the worst case,
 148 * the runtime of quickselect could regress to O(n^2). To mitigate this,
 149 * algorithms like median-of-medians exist, which can guarantee O(n) even
 150 * in the worst case. However, these algorithms come with a higher
 151 * overhead and are more complex to implement, making quickselect a
 152 * pragmatic choice for our use case.
 153 *
 154 * Warning: the input array gets modified!
 155 */
 156static s64 cros_ec_sensor_ring_median(s64 *array, size_t length)
 157{
 158	int lo = 0;
 159	int hi = length - 1;
 160
 161	while (lo <= hi) {
 162		int mid = lo + (hi - lo) / 2;
 163		int pivot, i;
 164
 165		if (array[lo] > array[mid])
 166			cros_ec_sensor_ring_median_swap(&array[lo], &array[mid]);
 167		if (array[lo] > array[hi])
 168			cros_ec_sensor_ring_median_swap(&array[lo], &array[hi]);
 169		if (array[mid] < array[hi])
 170			cros_ec_sensor_ring_median_swap(&array[mid], &array[hi]);
 171
 172		pivot = array[hi];
 173		i = lo - 1;
 174
 175		for (int j = lo; j < hi; j++)
 176			if (array[j] < pivot)
 177				cros_ec_sensor_ring_median_swap(&array[++i], &array[j]);
 178
 179		/* The pivot's index corresponds to i+1. */
 180		cros_ec_sensor_ring_median_swap(&array[i + 1], &array[hi]);
 181		if (i + 1 == length / 2)
 182			return array[i + 1];
 183		if (i + 1 > length / 2)
 184			hi = i;
 185		else
 186			lo = i + 2;
 187	}
 188
 189	/* Should never reach here. */
 190	return -1;
 191}
 192
 193/*
 194 * IRQ Timestamp Filtering
 195 *
 196 * Lower down in cros_ec_sensor_ring_process_event(), for each sensor event
 197 * we have to calculate it's timestamp in the AP timebase. There are 3 time
 198 * points:
 199 *   a - EC timebase, sensor event
 200 *   b - EC timebase, IRQ
 201 *   c - AP timebase, IRQ
 202 *   a' - what we want: sensor even in AP timebase
 203 *
 204 * While a and b are recorded at accurate times (due to the EC real time
 205 * nature); c is pretty untrustworthy, even though it's recorded the
 206 * first thing in ec_irq_handler(). There is a very good chance we'll get
 207 * added latency due to:
 208 *   other irqs
 209 *   ddrfreq
 210 *   cpuidle
 211 *
 212 * Normally a' = c - b + a, but if we do that naive math any jitter in c
 213 * will get coupled in a', which we don't want. We want a function
 214 * a' = cros_ec_sensor_ring_ts_filter(a) which will filter out outliers in c.
 215 *
 216 * Think of a graph of AP time(b) on the y axis vs EC time(c) on the x axis.
 217 * The slope of the line won't be exactly 1, there will be some clock drift
 218 * between the 2 chips for various reasons (mechanical stress, temperature,
 219 * voltage). We need to extrapolate values for a future x, without trusting
 220 * recent y values too much.
 221 *
 222 * We use a median filter for the slope, then another median filter for the
 223 * y-intercept to calculate this function:
 224 *   dx[n] = x[n-1] - x[n]
 225 *   dy[n] = x[n-1] - x[n]
 226 *   m[n] = dy[n] / dx[n]
 227 *   median_m = median(m[n-k:n])
 228 *   error[i] = y[n-i] - median_m * x[n-i]
 229 *   median_error = median(error[:k])
 230 *   predicted_y = median_m * x + median_error
 231 *
 232 * Implementation differences from above:
 233 * - Redefined y to be actually c - b, this gives us a lot more precision
 234 * to do the math. (c-b)/b variations are more obvious than c/b variations.
 235 * - Since we don't have floating point, any operations involving slope are
 236 * done using fixed point math (*M_PRECISION)
 237 * - Since x and y grow with time, we keep zeroing the graph (relative to
 238 * the last sample), this way math involving *x[n-i] will not overflow
 239 * - EC timestamps are kept in us, it improves the slope calculation precision
 240 */
 241
 242/**
 243 * cros_ec_sensor_ring_ts_filter_update() - Update filter history.
 244 *
 245 * @state: Filter information.
 246 * @b: IRQ timestamp, EC timebase (us)
 247 * @c: IRQ timestamp, AP timebase (ns)
 248 *
 249 * Given a new IRQ timestamp pair (EC and AP timebases), add it to the filter
 250 * history.
 251 */
 252static void
 253cros_ec_sensor_ring_ts_filter_update(struct cros_ec_sensors_ts_filter_state
 254				     *state,
 255				     s64 b, s64 c)
 256{
 257	s64 x, y;
 258	s64 dx, dy;
 259	s64 m; /* stored as *M_PRECISION */
 260	s64 *m_history_copy = state->temp_buf;
 261	s64 *error = state->temp_buf;
 262	int i;
 263
 264	/* we trust b the most, that'll be our independent variable */
 265	x = b;
 266	/* y is the offset between AP and EC times, in ns */
 267	y = c - b * 1000;
 268
 269	dx = (state->x_history[0] + state->x_offset) - x;
 270	if (dx == 0)
 271		return; /* we already have this irq in the history */
 272	dy = (state->y_history[0] + state->y_offset) - y;
 273	m = div64_s64(dy * M_PRECISION, dx);
 274
 275	/* Empty filter if we haven't seen any action in a while. */
 276	if (-dx > TS_HISTORY_BORED_US)
 277		state->history_len = 0;
 278
 279	/* Move everything over, also update offset to all absolute coords .*/
 280	for (i = state->history_len - 1; i >= 1; i--) {
 281		state->x_history[i] = state->x_history[i - 1] + dx;
 282		state->y_history[i] = state->y_history[i - 1] + dy;
 283
 284		state->m_history[i] = state->m_history[i - 1];
 285		/*
 286		 * Also use the same loop to copy m_history for future
 287		 * median extraction.
 288		 */
 289		m_history_copy[i] = state->m_history[i - 1];
 290	}
 291
 292	/* Store the x and y, but remember offset is actually last sample. */
 293	state->x_offset = x;
 294	state->y_offset = y;
 295	state->x_history[0] = 0;
 296	state->y_history[0] = 0;
 297
 298	state->m_history[0] = m;
 299	m_history_copy[0] = m;
 300
 301	if (state->history_len < CROS_EC_SENSORHUB_TS_HISTORY_SIZE)
 302		state->history_len++;
 303
 304	/* Precalculate things for the filter. */
 305	if (state->history_len > TS_HISTORY_THRESHOLD) {
 306		state->median_m =
 307		    cros_ec_sensor_ring_median(m_history_copy,
 308					       state->history_len - 1);
 309
 310		/*
 311		 * Calculate y-intercepts as if m_median is the slope and
 312		 * points in the history are on the line. median_error will
 313		 * still be in the offset coordinate system.
 314		 */
 315		for (i = 0; i < state->history_len; i++)
 316			error[i] = state->y_history[i] -
 317				div_s64(state->median_m * state->x_history[i],
 318					M_PRECISION);
 319		state->median_error =
 320			cros_ec_sensor_ring_median(error, state->history_len);
 321	} else {
 322		state->median_m = 0;
 323		state->median_error = 0;
 324	}
 325	trace_cros_ec_sensorhub_filter(state, dx, dy);
 326}
 327
 328/**
 329 * cros_ec_sensor_ring_ts_filter() - Translate EC timebase timestamp to AP
 330 *                                   timebase
 331 *
 332 * @state: filter information.
 333 * @x: any ec timestamp (us):
 334 *
 335 * cros_ec_sensor_ring_ts_filter(a) => a' event timestamp, AP timebase
 336 * cros_ec_sensor_ring_ts_filter(b) => calculated timestamp when the EC IRQ
 337 *                           should have happened on the AP, with low jitter
 338 *
 339 * Note: The filter will only activate once state->history_len goes
 340 * over TS_HISTORY_THRESHOLD. Otherwise it'll just do the naive c - b + a
 341 * transform.
 342 *
 343 * How to derive the formula, starting from:
 344 *   f(x) = median_m * x + median_error
 345 * That's the calculated AP - EC offset (at the x point in time)
 346 * Undo the coordinate system transform:
 347 *   f(x) = median_m * (x - x_offset) + median_error + y_offset
 348 * Remember to undo the "y = c - b * 1000" modification:
 349 *   f(x) = median_m * (x - x_offset) + median_error + y_offset + x * 1000
 350 *
 351 * Return: timestamp in AP timebase (ns)
 352 */
 353static s64
 354cros_ec_sensor_ring_ts_filter(struct cros_ec_sensors_ts_filter_state *state,
 355			      s64 x)
 356{
 357	return div_s64(state->median_m * (x - state->x_offset), M_PRECISION)
 358	       + state->median_error + state->y_offset + x * 1000;
 359}
 360
 361/*
 362 * Since a and b were originally 32 bit values from the EC,
 363 * they overflow relatively often, casting is not enough, so we need to
 364 * add an offset.
 365 */
 366static void
 367cros_ec_sensor_ring_fix_overflow(s64 *ts,
 368				 const s64 overflow_period,
 369				 struct cros_ec_sensors_ec_overflow_state
 370				 *state)
 371{
 372	s64 adjust;
 373
 374	*ts += state->offset;
 375	if (abs(state->last - *ts) > (overflow_period / 2)) {
 376		adjust = state->last > *ts ? overflow_period : -overflow_period;
 377		state->offset += adjust;
 378		*ts += adjust;
 379	}
 380	state->last = *ts;
 381}
 382
 383static void
 384cros_ec_sensor_ring_check_for_past_timestamp(struct cros_ec_sensorhub
 385					     *sensorhub,
 386					     struct cros_ec_sensors_ring_sample
 387					     *sample)
 388{
 389	const u8 sensor_id = sample->sensor_id;
 390
 391	/* If this event is earlier than one we saw before... */
 392	if (sensorhub->batch_state[sensor_id].newest_sensor_event >
 393	    sample->timestamp)
 394		/* mark it for spreading. */
 395		sample->timestamp =
 396			sensorhub->batch_state[sensor_id].last_ts;
 397	else
 398		sensorhub->batch_state[sensor_id].newest_sensor_event =
 399			sample->timestamp;
 400}
 401
 402/**
 403 * cros_ec_sensor_ring_process_event() - Process one EC FIFO event
 404 *
 405 * @sensorhub: Sensor Hub object.
 406 * @fifo_info: FIFO information from the EC (includes b point, EC timebase).
 407 * @fifo_timestamp: EC IRQ, kernel timebase (aka c).
 408 * @current_timestamp: calculated event timestamp, kernel timebase (aka a').
 409 * @in: incoming FIFO event from EC (includes a point, EC timebase).
 410 * @out: outgoing event to user space (includes a').
 411 *
 412 * Process one EC event, add it in the ring if necessary.
 413 *
 414 * Return: true if out event has been populated.
 415 */
 416static bool
 417cros_ec_sensor_ring_process_event(struct cros_ec_sensorhub *sensorhub,
 418				const struct ec_response_motion_sense_fifo_info
 419				*fifo_info,
 420				const ktime_t fifo_timestamp,
 421				ktime_t *current_timestamp,
 422				struct ec_response_motion_sensor_data *in,
 423				struct cros_ec_sensors_ring_sample *out)
 424{
 425	const s64 now = cros_ec_get_time_ns();
 426	int axis, async_flags;
 427
 428	/* Do not populate the filter based on asynchronous events. */
 429	async_flags = in->flags &
 430		(MOTIONSENSE_SENSOR_FLAG_ODR | MOTIONSENSE_SENSOR_FLAG_FLUSH);
 431
 432	if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP && !async_flags) {
 433		s64 a = in->timestamp;
 434		s64 b = fifo_info->timestamp;
 435		s64 c = fifo_timestamp;
 436
 437		cros_ec_sensor_ring_fix_overflow(&a, 1LL << 32,
 438					  &sensorhub->overflow_a);
 439		cros_ec_sensor_ring_fix_overflow(&b, 1LL << 32,
 440					  &sensorhub->overflow_b);
 441
 442		if (sensorhub->tight_timestamps) {
 443			cros_ec_sensor_ring_ts_filter_update(
 444					&sensorhub->filter, b, c);
 445			*current_timestamp = cros_ec_sensor_ring_ts_filter(
 446					&sensorhub->filter, a);
 447		} else {
 448			s64 new_timestamp;
 449
 450			/*
 451			 * Disable filtering since we might add more jitter
 452			 * if b is in a random point in time.
 453			 */
 454			new_timestamp = c - b * 1000 + a * 1000;
 455			/*
 456			 * The timestamp can be stale if we had to use the fifo
 457			 * info timestamp.
 458			 */
 459			if (new_timestamp - *current_timestamp > 0)
 460				*current_timestamp = new_timestamp;
 461		}
 462		trace_cros_ec_sensorhub_timestamp(in->timestamp,
 463						  fifo_info->timestamp,
 464						  fifo_timestamp,
 465						  *current_timestamp,
 466						  now);
 467	}
 468
 469	if (in->flags & MOTIONSENSE_SENSOR_FLAG_ODR) {
 470		if (sensorhub->tight_timestamps) {
 471			sensorhub->batch_state[in->sensor_num].last_len = 0;
 472			sensorhub->batch_state[in->sensor_num].penul_len = 0;
 473		}
 474		/*
 475		 * ODR change is only useful for the sensor_ring, it does not
 476		 * convey information to clients.
 477		 */
 478		return false;
 479	}
 480
 481	if (in->flags & MOTIONSENSE_SENSOR_FLAG_FLUSH) {
 482		out->sensor_id = in->sensor_num;
 483		out->timestamp = *current_timestamp;
 484		out->flag = in->flags;
 485		if (sensorhub->tight_timestamps)
 486			sensorhub->batch_state[out->sensor_id].last_len = 0;
 487		/*
 488		 * No other payload information provided with
 489		 * flush ack.
 490		 */
 491		return true;
 492	}
 493
 494	if (in->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP)
 495		/* If we just have a timestamp, skip this entry. */
 496		return false;
 497
 498	/* Regular sample */
 499	out->sensor_id = in->sensor_num;
 500	trace_cros_ec_sensorhub_data(in->sensor_num,
 501				     fifo_info->timestamp,
 502				     fifo_timestamp,
 503				     *current_timestamp,
 504				     now);
 505
 506	if (*current_timestamp - now > 0) {
 507		/*
 508		 * This fix is needed to overcome the timestamp filter putting
 509		 * events in the future.
 510		 */
 511		sensorhub->future_timestamp_total_ns +=
 512			*current_timestamp - now;
 513		if (++sensorhub->future_timestamp_count ==
 514				FUTURE_TS_ANALYTICS_COUNT_MAX) {
 515			s64 avg = div_s64(sensorhub->future_timestamp_total_ns,
 516					sensorhub->future_timestamp_count);
 517			dev_warn_ratelimited(sensorhub->dev,
 518					     "100 timestamps in the future, %lldns shaved on average\n",
 519					     avg);
 520			sensorhub->future_timestamp_count = 0;
 521			sensorhub->future_timestamp_total_ns = 0;
 522		}
 523		out->timestamp = now;
 524	} else {
 525		out->timestamp = *current_timestamp;
 526	}
 527
 528	out->flag = in->flags;
 529	for (axis = 0; axis < 3; axis++)
 530		out->vector[axis] = in->data[axis];
 531
 532	if (sensorhub->tight_timestamps)
 533		cros_ec_sensor_ring_check_for_past_timestamp(sensorhub, out);
 534	return true;
 535}
 536
 537/*
 538 * cros_ec_sensor_ring_spread_add: Calculate proper timestamps then add to
 539 *                                 ringbuffer.
 540 *
 541 * This is the new spreading code, assumes every sample's timestamp
 542 * precedes the sample. Run if tight_timestamps == true.
 543 *
 544 * Sometimes the EC receives only one interrupt (hence timestamp) for
 545 * a batch of samples. Only the first sample will have the correct
 546 * timestamp. So we must interpolate the other samples.
 547 * We use the previous batch timestamp and our current batch timestamp
 548 * as a way to calculate period, then spread the samples evenly.
 549 *
 550 * s0 int, 0ms
 551 * s1 int, 10ms
 552 * s2 int, 20ms
 553 * 30ms point goes by, no interrupt, previous one is still asserted
 554 * downloading s2 and s3
 555 * s3 sample, 20ms (incorrect timestamp)
 556 * s4 int, 40ms
 557 *
 558 * The batches are [(s0), (s1), (s2, s3), (s4)]. Since the 3rd batch
 559 * has 2 samples in them, we adjust the timestamp of s3.
 560 * s2 - s1 = 10ms, so s3 must be s2 + 10ms => 20ms. If s1 would have
 561 * been part of a bigger batch things would have gotten a little
 562 * more complicated.
 563 *
 564 * Note: we also assume another sensor sample doesn't break up a batch
 565 * in 2 or more partitions. Example, there can't ever be a sync sensor
 566 * in between S2 and S3. This simplifies the following code.
 567 */
 568static void
 569cros_ec_sensor_ring_spread_add(struct cros_ec_sensorhub *sensorhub,
 570			       unsigned long sensor_mask,
 571			       struct cros_ec_sensors_ring_sample *last_out)
 572{
 573	struct cros_ec_sensors_ring_sample *batch_start, *next_batch_start;
 574	int id;
 575
 576	for_each_set_bit(id, &sensor_mask, sensorhub->sensor_num) {
 577		for (batch_start = sensorhub->ring; batch_start < last_out;
 578		     batch_start = next_batch_start) {
 579			/*
 580			 * For each batch (where all samples have the same
 581			 * timestamp).
 582			 */
 583			int batch_len, sample_idx;
 584			struct cros_ec_sensors_ring_sample *batch_end =
 585				batch_start;
 586			struct cros_ec_sensors_ring_sample *s;
 587			s64 batch_timestamp = batch_start->timestamp;
 588			s64 sample_period;
 589
 590			/*
 591			 * Skip over batches that start with the sensor types
 592			 * we're not looking at right now.
 593			 */
 594			if (batch_start->sensor_id != id) {
 595				next_batch_start = batch_start + 1;
 596				continue;
 597			}
 598
 599			/*
 600			 * Do not start a batch
 601			 * from a flush, as it happens asynchronously to the
 602			 * regular flow of events.
 603			 */
 604			if (batch_start->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH) {
 605				cros_sensorhub_send_sample(sensorhub,
 606							   batch_start);
 607				next_batch_start = batch_start + 1;
 608				continue;
 609			}
 610
 611			if (batch_start->timestamp <=
 612			    sensorhub->batch_state[id].last_ts) {
 613				batch_timestamp =
 614					sensorhub->batch_state[id].last_ts;
 615				batch_len = sensorhub->batch_state[id].last_len;
 616
 617				sample_idx = batch_len;
 618
 619				sensorhub->batch_state[id].last_ts =
 620				  sensorhub->batch_state[id].penul_ts;
 621				sensorhub->batch_state[id].last_len =
 622				  sensorhub->batch_state[id].penul_len;
 623			} else {
 624				/*
 625				 * Push first sample in the batch to the,
 626				 * kfifo, it's guaranteed to be correct, the
 627				 * rest will follow later on.
 628				 */
 629				sample_idx = 1;
 630				batch_len = 1;
 631				cros_sensorhub_send_sample(sensorhub,
 632							   batch_start);
 633				batch_start++;
 634			}
 635
 636			/* Find all samples have the same timestamp. */
 637			for (s = batch_start; s < last_out; s++) {
 638				if (s->sensor_id != id)
 639					/*
 640					 * Skip over other sensor types that
 641					 * are interleaved, don't count them.
 642					 */
 643					continue;
 644				if (s->timestamp != batch_timestamp)
 645					/* we discovered the next batch */
 646					break;
 647				if (s->flag & MOTIONSENSE_SENSOR_FLAG_FLUSH)
 648					/* break on flush packets */
 649					break;
 650				batch_end = s;
 651				batch_len++;
 652			}
 653
 654			if (batch_len == 1)
 655				goto done_with_this_batch;
 656
 657			/* Can we calculate period? */
 658			if (sensorhub->batch_state[id].last_len == 0) {
 659				dev_warn(sensorhub->dev, "Sensor %d: lost %d samples when spreading\n",
 660					 id, batch_len - 1);
 661				goto done_with_this_batch;
 662				/*
 663				 * Note: we're dropping the rest of the samples
 664				 * in this batch since we have no idea where
 665				 * they're supposed to go without a period
 666				 * calculation.
 667				 */
 668			}
 669
 670			sample_period = div_s64(batch_timestamp -
 671				sensorhub->batch_state[id].last_ts,
 672				sensorhub->batch_state[id].last_len);
 673			dev_dbg(sensorhub->dev,
 674				"Adjusting %d samples, sensor %d last_batch @%lld (%d samples) batch_timestamp=%lld => period=%lld\n",
 675				batch_len, id,
 676				sensorhub->batch_state[id].last_ts,
 677				sensorhub->batch_state[id].last_len,
 678				batch_timestamp,
 679				sample_period);
 680
 681			/*
 682			 * Adjust timestamps of the samples then push them to
 683			 * kfifo.
 684			 */
 685			for (s = batch_start; s <= batch_end; s++) {
 686				if (s->sensor_id != id)
 687					/*
 688					 * Skip over other sensor types that
 689					 * are interleaved, don't change them.
 690					 */
 691					continue;
 692
 693				s->timestamp = batch_timestamp +
 694					sample_period * sample_idx;
 695				sample_idx++;
 696
 697				cros_sensorhub_send_sample(sensorhub, s);
 698			}
 699
 700done_with_this_batch:
 701			sensorhub->batch_state[id].penul_ts =
 702				sensorhub->batch_state[id].last_ts;
 703			sensorhub->batch_state[id].penul_len =
 704				sensorhub->batch_state[id].last_len;
 705
 706			sensorhub->batch_state[id].last_ts =
 707				batch_timestamp;
 708			sensorhub->batch_state[id].last_len = batch_len;
 709
 710			next_batch_start = batch_end + 1;
 711		}
 712	}
 713}
 714
 715/*
 716 * cros_ec_sensor_ring_spread_add_legacy: Calculate proper timestamps then
 717 * add to ringbuffer (legacy).
 718 *
 719 * Note: This assumes we're running old firmware, where timestamp
 720 * is inserted after its sample(s)e. There can be several samples between
 721 * timestamps, so several samples can have the same timestamp.
 722 *
 723 *                        timestamp | count
 724 *                        -----------------
 725 *          1st sample --> TS1      | 1
 726 *                         TS2      | 2
 727 *                         TS2      | 3
 728 *                         TS3      | 4
 729 *           last_out -->
 730 *
 731 *
 732 * We spread time for the samples using period p = (current - TS1)/4.
 733 * between TS1 and TS2: [TS1+p/4, TS1+2p/4, TS1+3p/4, current_timestamp].
 734 *
 735 */
 736static void
 737cros_ec_sensor_ring_spread_add_legacy(struct cros_ec_sensorhub *sensorhub,
 738				      unsigned long sensor_mask,
 739				      s64 current_timestamp,
 740				      struct cros_ec_sensors_ring_sample
 741				      *last_out)
 742{
 743	struct cros_ec_sensors_ring_sample *out;
 744	int i;
 745
 746	for_each_set_bit(i, &sensor_mask, sensorhub->sensor_num) {
 747		s64 timestamp;
 748		int count = 0;
 749		s64 time_period;
 750
 751		for (out = sensorhub->ring; out < last_out; out++) {
 752			if (out->sensor_id != i)
 753				continue;
 754
 755			/* Timestamp to start with */
 756			timestamp = out->timestamp;
 757			out++;
 758			count = 1;
 759			break;
 760		}
 761		for (; out < last_out; out++) {
 762			/* Find last sample. */
 763			if (out->sensor_id != i)
 764				continue;
 765			count++;
 766		}
 767		if (count == 0)
 768			continue;
 769
 770		/* Spread uniformly between the first and last samples. */
 771		time_period = div_s64(current_timestamp - timestamp, count);
 772
 773		for (out = sensorhub->ring; out < last_out; out++) {
 774			if (out->sensor_id != i)
 775				continue;
 776			timestamp += time_period;
 777			out->timestamp = timestamp;
 778		}
 779	}
 780
 781	/* Push the event into the kfifo */
 782	for (out = sensorhub->ring; out < last_out; out++)
 783		cros_sensorhub_send_sample(sensorhub, out);
 784}
 785
 786/**
 787 * cros_ec_sensorhub_ring_handler() - The trigger handler function
 788 *
 789 * @sensorhub: Sensor Hub object.
 790 *
 791 * Called by the notifier, process the EC sensor FIFO queue.
 792 */
 793static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
 794{
 795	struct ec_response_motion_sense_fifo_info *fifo_info =
 796		sensorhub->fifo_info;
 797	struct cros_ec_dev *ec = sensorhub->ec;
 798	ktime_t fifo_timestamp, current_timestamp;
 799	int i, j, number_data, ret;
 800	unsigned long sensor_mask = 0;
 801	struct ec_response_motion_sensor_data *in;
 802	struct cros_ec_sensors_ring_sample *out, *last_out;
 803
 804	mutex_lock(&sensorhub->cmd_lock);
 805
 806	/* Get FIFO information if there are lost vectors. */
 807	if (fifo_info->total_lost) {
 808		int fifo_info_length =
 809			sizeof(struct ec_response_motion_sense_fifo_info) +
 810			sizeof(u16) * sensorhub->sensor_num;
 811
 812		/* Need to retrieve the number of lost vectors per sensor */
 813		sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
 814		sensorhub->msg->outsize = 1;
 815		sensorhub->msg->insize = fifo_info_length;
 816
 817		if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
 818			goto error;
 819
 820		memcpy(fifo_info, &sensorhub->resp->fifo_info,
 821		       fifo_info_length);
 822
 823		/*
 824		 * Update collection time, will not be as precise as the
 825		 * non-error case.
 826		 */
 827		fifo_timestamp = cros_ec_get_time_ns();
 828	} else {
 829		fifo_timestamp = sensorhub->fifo_timestamp[
 830			CROS_EC_SENSOR_NEW_TS];
 831	}
 832
 833	if (fifo_info->count > sensorhub->fifo_size ||
 834	    fifo_info->size != sensorhub->fifo_size) {
 835		dev_warn(sensorhub->dev,
 836			 "Mismatch EC data: count %d, size %d - expected %d\n",
 837			 fifo_info->count, fifo_info->size,
 838			 sensorhub->fifo_size);
 839		goto error;
 840	}
 841
 842	/* Copy elements in the main fifo */
 843	current_timestamp = sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS];
 844	out = sensorhub->ring;
 845	for (i = 0; i < fifo_info->count; i += number_data) {
 846		sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_READ;
 847		sensorhub->params->fifo_read.max_data_vector =
 848			fifo_info->count - i;
 849		sensorhub->msg->outsize =
 850			sizeof(struct ec_params_motion_sense);
 851		sensorhub->msg->insize =
 852			sizeof(sensorhub->resp->fifo_read) +
 853			sensorhub->params->fifo_read.max_data_vector *
 854			  sizeof(struct ec_response_motion_sensor_data);
 855		ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
 856		if (ret < 0) {
 857			dev_warn(sensorhub->dev, "Fifo error: %d\n", ret);
 858			break;
 859		}
 860		number_data = sensorhub->resp->fifo_read.number_data;
 861		if (number_data == 0) {
 862			dev_dbg(sensorhub->dev, "Unexpected empty FIFO\n");
 863			break;
 864		}
 865		if (number_data > fifo_info->count - i) {
 866			dev_warn(sensorhub->dev,
 867				 "Invalid EC data: too many entry received: %d, expected %d\n",
 868				 number_data, fifo_info->count - i);
 869			break;
 870		}
 871		if (out + number_data >
 872		    sensorhub->ring + fifo_info->count) {
 873			dev_warn(sensorhub->dev,
 874				 "Too many samples: %d (%zd data) to %d entries for expected %d entries\n",
 875				 i, out - sensorhub->ring, i + number_data,
 876				 fifo_info->count);
 877			break;
 878		}
 879
 880		for (in = sensorhub->resp->fifo_read.data, j = 0;
 881		     j < number_data; j++, in++) {
 882			if (cros_ec_sensor_ring_process_event(
 883						sensorhub, fifo_info,
 884						fifo_timestamp,
 885						&current_timestamp,
 886						in, out)) {
 887				sensor_mask |= BIT(in->sensor_num);
 888				out++;
 889			}
 890		}
 891	}
 892	mutex_unlock(&sensorhub->cmd_lock);
 893	last_out = out;
 894
 895	if (out == sensorhub->ring)
 896		/* Unexpected empty FIFO. */
 897		goto ring_handler_end;
 898
 899	/*
 900	 * Check if current_timestamp is ahead of the last sample. Normally,
 901	 * the EC appends a timestamp after the last sample, but if the AP
 902	 * is slow to respond to the IRQ, the EC may have added new samples.
 903	 * Use the FIFO info timestamp as last timestamp then.
 904	 */
 905	if (!sensorhub->tight_timestamps &&
 906	    (last_out - 1)->timestamp == current_timestamp)
 907		current_timestamp = fifo_timestamp;
 908
 909	/* Warn on lost samples. */
 910	if (fifo_info->total_lost)
 911		for (i = 0; i < sensorhub->sensor_num; i++) {
 912			if (fifo_info->lost[i]) {
 913				dev_warn_ratelimited(sensorhub->dev,
 914						     "Sensor %d: lost: %d out of %d\n",
 915						     i, fifo_info->lost[i],
 916						     fifo_info->total_lost);
 917				if (sensorhub->tight_timestamps)
 918					sensorhub->batch_state[i].last_len = 0;
 919			}
 920		}
 921
 922	/*
 923	 * Spread samples in case of batching, then add them to the
 924	 * ringbuffer.
 925	 */
 926	if (sensorhub->tight_timestamps)
 927		cros_ec_sensor_ring_spread_add(sensorhub, sensor_mask,
 928					       last_out);
 929	else
 930		cros_ec_sensor_ring_spread_add_legacy(sensorhub, sensor_mask,
 931						      current_timestamp,
 932						      last_out);
 933
 934ring_handler_end:
 935	sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] = current_timestamp;
 936	return;
 937
 938error:
 939	mutex_unlock(&sensorhub->cmd_lock);
 940}
 941
 942static int cros_ec_sensorhub_event(struct notifier_block *nb,
 943				   unsigned long queued_during_suspend,
 944				   void *_notify)
 945{
 946	struct cros_ec_sensorhub *sensorhub;
 947	struct cros_ec_device *ec_dev;
 948
 949	sensorhub = container_of(nb, struct cros_ec_sensorhub, notifier);
 950	ec_dev = sensorhub->ec->ec_dev;
 951
 952	if (ec_dev->event_data.event_type != EC_MKBP_EVENT_SENSOR_FIFO)
 953		return NOTIFY_DONE;
 954
 955	if (ec_dev->event_size != sizeof(ec_dev->event_data.data.sensor_fifo)) {
 956		dev_warn(ec_dev->dev, "Invalid fifo info size\n");
 957		return NOTIFY_DONE;
 958	}
 959
 960	if (queued_during_suspend)
 961		return NOTIFY_OK;
 962
 963	memcpy(sensorhub->fifo_info, &ec_dev->event_data.data.sensor_fifo.info,
 964	       sizeof(*sensorhub->fifo_info));
 965	sensorhub->fifo_timestamp[CROS_EC_SENSOR_NEW_TS] =
 966		ec_dev->last_event_time;
 967	cros_ec_sensorhub_ring_handler(sensorhub);
 968
 969	return NOTIFY_OK;
 970}
 971
 972/**
 973 * cros_ec_sensorhub_ring_allocate() - Prepare the FIFO functionality if the EC
 974 *				       supports it.
 975 *
 976 * @sensorhub : Sensor Hub object.
 977 *
 978 * Return: 0 on success.
 979 */
 980int cros_ec_sensorhub_ring_allocate(struct cros_ec_sensorhub *sensorhub)
 981{
 982	int fifo_info_length =
 983		sizeof(struct ec_response_motion_sense_fifo_info) +
 984		sizeof(u16) * sensorhub->sensor_num;
 985
 986	/* Allocate the array for lost events. */
 987	sensorhub->fifo_info = devm_kzalloc(sensorhub->dev, fifo_info_length,
 988					    GFP_KERNEL);
 989	if (!sensorhub->fifo_info)
 990		return -ENOMEM;
 991
 992	/*
 993	 * Allocate the callback area based on the number of sensors.
 994	 * Add one for the sensor ring.
 995	 */
 996	sensorhub->push_data = devm_kcalloc(sensorhub->dev,
 997			sensorhub->sensor_num,
 998			sizeof(*sensorhub->push_data),
 999			GFP_KERNEL);
1000	if (!sensorhub->push_data)
1001		return -ENOMEM;
1002
1003	sensorhub->tight_timestamps = cros_ec_check_features(
1004			sensorhub->ec,
1005			EC_FEATURE_MOTION_SENSE_TIGHT_TIMESTAMPS);
1006
1007	if (sensorhub->tight_timestamps) {
1008		sensorhub->batch_state = devm_kcalloc(sensorhub->dev,
1009				sensorhub->sensor_num,
1010				sizeof(*sensorhub->batch_state),
1011				GFP_KERNEL);
1012		if (!sensorhub->batch_state)
1013			return -ENOMEM;
1014	}
1015
1016	return 0;
1017}
1018
1019/**
1020 * cros_ec_sensorhub_ring_add() - Add the FIFO functionality if the EC
1021 *				  supports it.
1022 *
1023 * @sensorhub : Sensor Hub object.
1024 *
1025 * Return: 0 on success.
1026 */
1027int cros_ec_sensorhub_ring_add(struct cros_ec_sensorhub *sensorhub)
1028{
1029	struct cros_ec_dev *ec = sensorhub->ec;
1030	int ret;
1031	int fifo_info_length =
1032		sizeof(struct ec_response_motion_sense_fifo_info) +
1033		sizeof(u16) * sensorhub->sensor_num;
1034
1035	/* Retrieve FIFO information */
1036	sensorhub->msg->version = 2;
1037	sensorhub->params->cmd = MOTIONSENSE_CMD_FIFO_INFO;
1038	sensorhub->msg->outsize = 1;
1039	sensorhub->msg->insize = fifo_info_length;
1040
1041	ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
1042	if (ret < 0)
1043		return ret;
1044
1045	/*
1046	 * Allocate the full fifo. We need to copy the whole FIFO to set
1047	 * timestamps properly.
1048	 */
1049	sensorhub->fifo_size = sensorhub->resp->fifo_info.size;
1050	sensorhub->ring = devm_kcalloc(sensorhub->dev, sensorhub->fifo_size,
1051				       sizeof(*sensorhub->ring), GFP_KERNEL);
1052	if (!sensorhub->ring)
1053		return -ENOMEM;
1054
1055	sensorhub->fifo_timestamp[CROS_EC_SENSOR_LAST_TS] =
1056		cros_ec_get_time_ns();
1057
1058	/* Register the notifier that will act as a top half interrupt. */
1059	sensorhub->notifier.notifier_call = cros_ec_sensorhub_event;
1060	ret = blocking_notifier_chain_register(&ec->ec_dev->event_notifier,
1061					       &sensorhub->notifier);
1062	if (ret < 0)
1063		return ret;
1064
1065	/* Start collection samples. */
1066	return cros_ec_sensorhub_ring_fifo_enable(sensorhub, true);
1067}
1068
1069void cros_ec_sensorhub_ring_remove(void *arg)
1070{
1071	struct cros_ec_sensorhub *sensorhub = arg;
1072	struct cros_ec_device *ec_dev = sensorhub->ec->ec_dev;
1073
1074	/* Disable the ring, prevent EC interrupt to the AP for nothing. */
1075	cros_ec_sensorhub_ring_fifo_enable(sensorhub, false);
1076	blocking_notifier_chain_unregister(&ec_dev->event_notifier,
1077					   &sensorhub->notifier);
1078}