common: Move fifo logic out of motion_sense.c

This change is needed to allow better testing of the fifo
behavior. Additionally, motion_sense_fifo.c will only be compiled
if CONFIG_ACCEL_FIFO is defined. This behaviour requires a few
small changes to several boards and baseboards to make
sure that we only define CONFIG_ACCEL_FIFO when the MOTIONSENSE
task is present (some times that may be only in one section RW or
RO).

BUG=b:137758297
BRANCH=None
TEST=buildall and ran CTS on arcada

Change-Id: I2f7e4e436ba9568a35b7a0b2c8d53a73f198ba73
Signed-off-by: Yuval Peress <peress@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1704163
Reviewed-by: Alexandru M Stan <amstan@chromium.org>
Commit-Queue: Alexandru M Stan <amstan@chromium.org>

1 files changed, 403 insertions, 0 deletions

diff --git a/common/motion_sense_fifo.c b/common/motion_sense_fifo.c
new file mode 100644
index 0000000000..00c2f5a8cc
--- /dev/null
+++ b/common/motion_sense_fifo.c
@@ -0,0 +1,403 @@
+/* Copyright 2019 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "console.h"
+#include "hwtimer.h"
+#include "mkbp_event.h"
+#include "motion_sense_fifo.h"
+#include "queue.h"
+#include "tablet_mode.h"
+#include "util.h"
+
+#define CPRINTS(format, args...) cprints(CC_MOTION_SENSE, format, ## args)
+
+static inline int is_timestamp(struct ec_response_motion_sensor_data *data)
+{
+	return data->flags & MOTIONSENSE_SENSOR_FLAG_TIMESTAMP;
+}
+
+/* Need to wake up the AP */
+int wake_up_needed;
+
+/* Number of element the AP should collect */
+int fifo_queue_count;
+int fifo_int_enabled;
+
+struct queue motion_sense_fifo = QUEUE_NULL(
+	CONFIG_ACCEL_FIFO, struct ec_response_motion_sensor_data);
+int motion_sense_fifo_lost;
+
+/**
+ * Staged metadata for the motion_sense_fifo.
+ * @read_ts: The timestamp at which the staged data was read. This value will
+ *	serve as the upper bound for spreading
+ * @count: The total number of motion_sense_fifo entries that are currently
+ *	staged.
+ * @sample_count: The total number of sensor readings per sensor that are
+ *	currently staged.
+ * @requires_spreading: Flag used to shortcut the commit process. This should be
+ *	true iff at least one of sample_count[] > 1
+ */
+struct fifo_staged {
+	uint32_t read_ts;
+	uint16_t count;
+	uint8_t sample_count[SENSOR_COUNT];
+	uint8_t requires_spreading;
+};
+static struct fifo_staged fifo_staged;
+
+static inline struct ec_response_motion_sensor_data *
+get_motion_sense_fifo_head(void)
+{
+	return ((struct ec_response_motion_sensor_data *)
+		motion_sense_fifo.buffer) +
+	       (motion_sense_fifo.state->head &
+		motion_sense_fifo.unit_bytes);
+}
+
+/**
+ * Pop one entry from the motion sense fifo. Poping will give priority to
+ * committed data (data residing between the head and tail of the queue). If no
+ * committed data is available (all the data is staged), then this function will
+ * remove the oldest staged data by moving both the head and tail.
+ *
+ * As a side-effect of this function, it'll updated any appropriate lost and
+ * count variables.
+ *
+ * WARNING: This function MUST be called from within a locked context of
+ * g_sensor_mutex.
+ */
+static void motion_sense_fifo_pop(void)
+{
+	struct ec_response_motion_sensor_data *head =
+		get_motion_sense_fifo_head();
+	const size_t initial_count = queue_count(&motion_sense_fifo);
+
+	/* Check that we have something to pop. */
+	if (!initial_count && !fifo_staged.count)
+		return;
+
+	/*
+	 * If all the data is staged (nothing in the committed queue), we'll
+	 * need to move the head and the tail over to simulate poping from the
+	 * staged data.
+	 */
+	if (!initial_count)
+		queue_advance_tail(&motion_sense_fifo, 1);
+
+	/*
+	 * By not using queue_remove_unit we're avoiding an un-necessary memcpy.
+	 */
+	queue_advance_head(&motion_sense_fifo, 1);
+	motion_sense_fifo_lost++;
+
+	/* Increment lost counter if we have valid data. */
+	if (!is_timestamp(head))
+		motion_sensors[head->sensor_num].lost++;
+
+	/*
+	 * We're done if the initial count was non-zero and we only advanced the
+	 * head. Else, decrement the staged count and update staged metadata.
+	 */
+	if (initial_count)
+		return;
+
+	fifo_staged.count--;
+
+	/* If we removed a timestamp there's nothing else for us to do. */
+	if (is_timestamp(head))
+		return;
+
+	/*
+	 * Decrement sample count, if the count was 2 before, we might not need
+	 * to spread anymore. Loop through and check.
+	 */
+	if (--fifo_staged.sample_count[head->sensor_num] < 2) {
+		int i;
+
+		fifo_staged.requires_spreading = 0;
+		for (i = 0; i < SENSOR_COUNT; i++) {
+			if (fifo_staged.sample_count[i] > 1) {
+				fifo_staged.requires_spreading = 1;
+				break;
+			}
+		}
+	}
+}
+
+static void motion_sense_fifo_ensure_space(void)
+{
+	/* If we already have space just bail. */
+	if (queue_space(&motion_sense_fifo) > fifo_staged.count)
+		return;
+
+	/*
+	 * Pop at least 1 spot, but if all the following conditions are met we
+	 * will continue to pop:
+	 * 1. We're operating with tight timestamps.
+	 * 2. The new head isn't a timestamp.
+	 * 3. We have data that we can possibly pop.
+	 *
+	 * Removing more than one entry is needed because if we are using tight
+	 * timestamps and we pop a timestamp, then the next head is data, the AP
+	 * would assign a bad timestamp to it.
+	 */
+	do {
+		motion_sense_fifo_pop();
+	} while (IS_ENABLED(CONFIG_SENSOR_TIGHT_TIMESTAMPS) &&
+		 !is_timestamp(get_motion_sense_fifo_head()) &&
+		 queue_count(&motion_sense_fifo) + fifo_staged.count);
+}
+
+/*
+ * Do not use this function directly if you just want to add sensor data, use
+ * motion_sense_fifo_stage_data instead to get a proper timestamp too.
+ */
+static void motion_sense_fifo_stage_unit(
+	struct ec_response_motion_sensor_data *data,
+	struct motion_sensor_t *sensor,
+	int valid_data)
+{
+	struct queue_chunk chunk;
+	int i;
+
+	mutex_lock(&g_sensor_mutex);
+
+	for (i = 0; i < valid_data; i++)
+		sensor->xyz[i] = data->data[i];
+
+	/* For valid sensors, check if AP really needs this data */
+	if (valid_data) {
+		int removed;
+
+		if (sensor->oversampling_ratio == 0) {
+			mutex_unlock(&g_sensor_mutex);
+			return;
+		}
+		removed = sensor->oversampling++;
+		sensor->oversampling %= sensor->oversampling_ratio;
+		if (removed != 0) {
+			mutex_unlock(&g_sensor_mutex);
+			return;
+		}
+	}
+
+	/* Make sure we have room for the data */
+	motion_sense_fifo_ensure_space();
+	mutex_unlock(&g_sensor_mutex);
+
+	if (data->flags & MOTIONSENSE_SENSOR_FLAG_WAKEUP)
+		wake_up_needed = 1;
+	if (IS_ENABLED(CONFIG_TABLET_MODE))
+		data->flags |= (tablet_get_mode() ?
+			MOTIONSENSE_SENSOR_FLAG_TABLET_MODE : 0);
+
+	/*
+	 * Get the next writable block in the fifo. We don't need to lock this
+	 * because it will always be past the tail and thus the AP will never
+	 * read this until motion_sense_fifo_commit_data() is called.
+	 */
+	chunk = queue_get_write_chunk(
+		&motion_sense_fifo, fifo_staged.count);
+
+	if (!chunk.buffer) {
+		/*
+		 * This should never happen since we already ensured there was
+		 * space, but if there was a bug, we don't want to write to
+		 * address 0. Just don't add any data to the queue instead.
+		 */
+		CPRINTS("Failed to get write chunk for new fifo data!");
+		return;
+	}
+
+	/*
+	 * Save the data to the writable block and increment count. This data
+	 * will now reside AFTER the tail of the queue and will not be visible
+	 * to the AP until the motion_sense_fifo_commit_data() function is
+	 * called. Because count is incremented, the following staged data will
+	 * be written to the next available block and this one will remain
+	 * staged.
+	 */
+	memcpy(chunk.buffer, data, motion_sense_fifo.unit_bytes);
+	fifo_staged.count++;
+
+	/*
+	 * If we're using tight timestamps, and the current entry isn't a
+	 * timestamp we'll increment the sample_count for the given sensor.
+	 * If the new per-sensor sample count is greater than 1, we'll need to
+	 * spread.
+	 */
+	if (IS_ENABLED(CONFIG_SENSOR_TIGHT_TIMESTAMPS) &&
+	    !is_timestamp(data) &&
+	    ++fifo_staged.sample_count[data->sensor_num] > 1)
+		fifo_staged.requires_spreading = 1;
+}
+
+void motion_sense_insert_async_event(struct motion_sensor_t *sensor,
+				     enum motion_sense_async_event evt)
+{
+	struct ec_response_motion_sensor_data vector;
+
+	vector.flags = evt;
+	vector.timestamp = __hw_clock_source_read();
+	vector.sensor_num = sensor - motion_sensors;
+
+	motion_sense_fifo_stage_unit(&vector, sensor, 0);
+	motion_sense_fifo_commit_data();
+}
+
+void motion_sense_fifo_stage_timestamp(uint32_t timestamp)
+{
+	struct ec_response_motion_sensor_data vector;
+
+	vector.flags = MOTIONSENSE_SENSOR_FLAG_TIMESTAMP;
+	vector.timestamp = timestamp;
+	vector.sensor_num = 0;
+	motion_sense_fifo_stage_unit(&vector, NULL, 0);
+}
+
+void motion_sense_fifo_stage_data(struct ec_response_motion_sensor_data *data,
+				  struct motion_sensor_t *sensor,
+				  int valid_data,
+				  uint32_t time)
+{
+	if (IS_ENABLED(CONFIG_SENSOR_TIGHT_TIMESTAMPS)) {
+		/* First entry, save the time for spreading later. */
+		if (!fifo_staged.count)
+			fifo_staged.read_ts = __hw_clock_source_read();
+		motion_sense_fifo_stage_timestamp(time);
+	}
+	motion_sense_fifo_stage_unit(data, sensor, valid_data);
+}
+
+/**
+ * Peek into the staged data at a given offset. This function performs no bound
+ * checking and is purely for convenience.
+ */
+static inline struct ec_response_motion_sensor_data *
+motion_sense_peek_fifo_staged(size_t offset)
+{
+	return (struct ec_response_motion_sensor_data *)
+	       queue_get_write_chunk(&motion_sense_fifo, offset).buffer;
+}
+
+void motion_sense_fifo_commit_data(void)
+{
+	/*
+	 * Static data to use off stack. Note that next_timestamp should persist
+	 * and is only updated if the timestamp from the sensor is greater.
+	 */
+	static uint32_t data_periods[SENSOR_COUNT];
+	static uint32_t next_timestamp[SENSOR_COUNT];
+	struct ec_response_motion_sensor_data *data;
+	int i, window, sensor_num;
+
+	/* Nothing staged, no work to do. */
+	if (!fifo_staged.count)
+		return;
+
+	/*
+	 * If per-sensor event counts are never more than 1, no spreading is
+	 * needed. This will also catch cases where tight timestamps aren't
+	 * used.
+	 */
+	if (!fifo_staged.requires_spreading)
+		goto flush_data_end;
+
+	data = motion_sense_peek_fifo_staged(0);
+
+	/*
+	 * Spreading only makes sense if tight timestamps are used. In such case
+	 * entries are expected to be ordered: timestamp then data. If the first
+	 * entry isn't a timestamp we must have gotten out of sync. Just commit
+	 * all the data and skip the spreading.
+	 */
+	if (!is_timestamp(data)) {
+		CPRINTS("Spreading skipped, first entry is not a timestamp");
+		goto flush_data_end;
+	}
+
+	window = time_until(data->timestamp, fifo_staged.read_ts);
+
+	/* Update the data_periods as needed for this flush. */
+	for (i = 0; i < SENSOR_COUNT; i++) {
+		int period;
+
+		/* Skip empty sensors. */
+		if (!fifo_staged.sample_count[i])
+			continue;
+
+		period = motion_sensors[i].collection_rate;
+		/*
+		 * Clamp the sample period to the MIN of collection_rate and the
+		 * window length / sample counts.
+		 */
+		if (window)
+			period = MIN(period,
+				     window / fifo_staged.sample_count[i]);
+		data_periods[i] = period;
+	}
+
+	/*
+	 * Spread the timestamps.
+	 *
+	 * If we got this far that means that the tight timestamps config is
+	 * enabled. This means that we can expect the staged entries to have 1
+	 * or more timestamps followed by exactly 1 data entry. We'll loop
+	 * through the timestamps until we get to data. We only need to update
+	 * the timestamp right before it to keep things correct.
+	 */
+	for (i = 0; i < fifo_staged.count; i++) {
+		data = motion_sense_peek_fifo_staged(i);
+
+		/* Skip timestamp, we don't know the sensor number yet. */
+		if (is_timestamp(data))
+			continue;
+
+		/* Get the sensor number and point to the timestamp entry. */
+		sensor_num = data->sensor_num;
+		data = motion_sense_peek_fifo_staged(i - 1);
+
+		/* If the timestamp is after our computed next, skip ahead. */
+		if (time_after(data->timestamp, next_timestamp[sensor_num]))
+			next_timestamp[sensor_num] = data->timestamp;
+
+		/* Spread the timestamp and compute the expected next. */
+		data->timestamp = next_timestamp[sensor_num];
+		next_timestamp[sensor_num] += data_periods[sensor_num];
+	}
+
+flush_data_end:
+	/* Advance the tail and clear the staged metadata. */
+	mutex_lock(&g_sensor_mutex);
+	queue_advance_tail(&motion_sense_fifo, fifo_staged.count);
+	mutex_unlock(&g_sensor_mutex);
+
+	/* Reset metadata for next staging cycle. */
+	memset(&fifo_staged, 0, sizeof(fifo_staged));
+}
+
+void motion_sense_get_fifo_info(
+	struct ec_response_motion_sense_fifo_info *fifo_info)
+{
+	fifo_info->size = motion_sense_fifo.buffer_units;
+	mutex_lock(&g_sensor_mutex);
+	fifo_info->count = fifo_queue_count;
+	fifo_info->total_lost = motion_sense_fifo_lost;
+	mutex_unlock(&g_sensor_mutex);
+	fifo_info->timestamp = mkbp_last_event_time;
+}
+
+static int motion_sense_get_next_event(uint8_t *out)
+{
+	union ec_response_get_next_data *data =
+		(union ec_response_get_next_data *)out;
+	/* out is not padded. It has one byte for the event type */
+	motion_sense_get_fifo_info(&data->sensor_fifo.info);
+	return sizeof(data->sensor_fifo);
+}
+
+DECLARE_EVENT_SOURCE(EC_MKBP_EVENT_SENSOR_FIFO, motion_sense_get_next_event);
+