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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2020 Invensense, Inc.
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/iio/common/inv_sensors_timestamp.h>
/* compute jitter, min and max following jitter in per mille */
#define INV_SENSORS_TIMESTAMP_JITTER(_val, _jitter) \
(div_s64((_val) * (_jitter), 1000))
#define INV_SENSORS_TIMESTAMP_MIN(_val, _jitter) \
(((_val) * (1000 - (_jitter))) / 1000)
#define INV_SENSORS_TIMESTAMP_MAX(_val, _jitter) \
(((_val) * (1000 + (_jitter))) / 1000)
/* Add a new value inside an accumulator and update the estimate value */
static void inv_update_acc(struct inv_sensors_timestamp_acc *acc, uint32_t val)
{
uint64_t sum = 0;
size_t i;
acc->values[acc->idx++] = val;
if (acc->idx >= ARRAY_SIZE(acc->values))
acc->idx = 0;
/* compute the mean of all stored values, use 0 as empty slot */
for (i = 0; i < ARRAY_SIZE(acc->values); ++i) {
if (acc->values[i] == 0)
break;
sum += acc->values[i];
}
acc->val = div_u64(sum, i);
}
void inv_sensors_timestamp_init(struct inv_sensors_timestamp *ts,
const struct inv_sensors_timestamp_chip *chip)
{
memset(ts, 0, sizeof(*ts));
/* save chip parameters and compute min and max clock period */
ts->chip = *chip;
ts->min_period = INV_SENSORS_TIMESTAMP_MIN(chip->clock_period, chip->jitter);
ts->max_period = INV_SENSORS_TIMESTAMP_MAX(chip->clock_period, chip->jitter);
/* current multiplier and period values after reset */
ts->mult = chip->init_period / chip->clock_period;
ts->period = chip->init_period;
/* use theoretical value for chip period */
inv_update_acc(&ts->chip_period, chip->clock_period);
}
EXPORT_SYMBOL_NS_GPL(inv_sensors_timestamp_init, IIO_INV_SENSORS_TIMESTAMP);
int inv_sensors_timestamp_update_odr(struct inv_sensors_timestamp *ts,
uint32_t period, bool fifo)
{
uint32_t mult;
/* when FIFO is on, prevent odr change if one is already pending */
if (fifo && ts->new_mult != 0)
return -EAGAIN;
mult = period / ts->chip.clock_period;
if (mult != ts->mult)
ts->new_mult = mult;
/* When FIFO is off, directly apply the new ODR */
if (!fifo)
inv_sensors_timestamp_apply_odr(ts, 0, 0, 0);
return 0;
}
EXPORT_SYMBOL_NS_GPL(inv_sensors_timestamp_update_odr, IIO_INV_SENSORS_TIMESTAMP);
static bool inv_validate_period(struct inv_sensors_timestamp *ts, uint32_t period)
{
uint32_t period_min, period_max;
/* check that period is acceptable */
period_min = ts->min_period * ts->mult;
period_max = ts->max_period * ts->mult;
if (period > period_min && period < period_max)
return true;
else
return false;
}
static bool inv_update_chip_period(struct inv_sensors_timestamp *ts,
uint32_t period)
{
uint32_t new_chip_period;
if (!inv_validate_period(ts, period))
return false;
/* update chip internal period estimation */
new_chip_period = period / ts->mult;
inv_update_acc(&ts->chip_period, new_chip_period);
ts->period = ts->mult * ts->chip_period.val;
return true;
}
static void inv_align_timestamp_it(struct inv_sensors_timestamp *ts)
{
const int64_t period_min = ts->min_period * ts->mult;
const int64_t period_max = ts->max_period * ts->mult;
int64_t add_max, sub_max;
int64_t delta, jitter;
int64_t adjust;
/* delta time between last sample and last interrupt */
delta = ts->it.lo - ts->timestamp;
/* adjust timestamp while respecting jitter */
add_max = period_max - (int64_t)ts->period;
sub_max = period_min - (int64_t)ts->period;
jitter = INV_SENSORS_TIMESTAMP_JITTER((int64_t)ts->period, ts->chip.jitter);
if (delta > jitter)
adjust = add_max;
else if (delta < -jitter)
adjust = sub_max;
else
adjust = 0;
ts->timestamp += adjust;
}
void inv_sensors_timestamp_interrupt(struct inv_sensors_timestamp *ts,
size_t sample_nb, int64_t timestamp)
{
struct inv_sensors_timestamp_interval *it;
int64_t delta, interval;
uint32_t period;
bool valid = false;
if (sample_nb == 0)
return;
/* update interrupt timestamp and compute chip and sensor periods */
it = &ts->it;
it->lo = it->up;
it->up = timestamp;
delta = it->up - it->lo;
if (it->lo != 0) {
/* compute period: delta time divided by number of samples */
period = div_s64(delta, sample_nb);
valid = inv_update_chip_period(ts, period);
}
/* no previous data, compute theoritical value from interrupt */
if (ts->timestamp == 0) {
/* elapsed time: sensor period * sensor samples number */
interval = (int64_t)ts->period * (int64_t)sample_nb;
ts->timestamp = it->up - interval;
return;
}
/* if interrupt interval is valid, sync with interrupt timestamp */
if (valid)
inv_align_timestamp_it(ts);
}
EXPORT_SYMBOL_NS_GPL(inv_sensors_timestamp_interrupt, IIO_INV_SENSORS_TIMESTAMP);
void inv_sensors_timestamp_apply_odr(struct inv_sensors_timestamp *ts,
uint32_t fifo_period, size_t fifo_nb,
unsigned int fifo_no)
{
int64_t interval;
uint32_t fifo_mult;
if (ts->new_mult == 0)
return;
/* update to new multiplier and update period */
ts->mult = ts->new_mult;
ts->new_mult = 0;
ts->period = ts->mult * ts->chip_period.val;
/*
* After ODR change the time interval with the previous sample is
* undertermined (depends when the change occures). So we compute the
* timestamp from the current interrupt using the new FIFO period, the
* total number of samples and the current sample numero.
*/
if (ts->timestamp != 0) {
/* compute measured fifo period */
fifo_mult = fifo_period / ts->chip.clock_period;
fifo_period = fifo_mult * ts->chip_period.val;
/* computes time interval between interrupt and this sample */
interval = (int64_t)(fifo_nb - fifo_no) * (int64_t)fifo_period;
ts->timestamp = ts->it.up - interval;
}
}
EXPORT_SYMBOL_NS_GPL(inv_sensors_timestamp_apply_odr, IIO_INV_SENSORS_TIMESTAMP);
MODULE_AUTHOR("InvenSense, Inc.");
MODULE_DESCRIPTION("InvenSense sensors timestamp module");
MODULE_LICENSE("GPL");
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