1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
|
// 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)
{
/* when FIFO is on, prevent odr change if one is already pending */
if (fifo && ts->new_mult != 0)
return -EAGAIN;
ts->new_mult = period / ts->chip.clock_period;
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 mult)
{
uint32_t period_min, period_max;
/* check that period is acceptable */
period_min = ts->min_period * mult;
period_max = ts->max_period * 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 mult, uint32_t period)
{
uint32_t new_chip_period;
if (!inv_validate_period(ts, period, mult))
return false;
/* update chip internal period estimation */
new_chip_period = period / 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)
{
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 */
jitter = INV_SENSORS_TIMESTAMP_JITTER((int64_t)ts->period, ts->chip.jitter);
if (delta > jitter)
adjust = jitter;
else if (delta < -jitter)
adjust = -jitter;
else
adjust = 0;
ts->timestamp += adjust;
}
void inv_sensors_timestamp_interrupt(struct inv_sensors_timestamp *ts,
uint32_t fifo_period, size_t fifo_nb,
size_t sensor_nb, int64_t timestamp)
{
struct inv_sensors_timestamp_interval *it;
int64_t delta, interval;
const uint32_t fifo_mult = fifo_period / ts->chip.clock_period;
uint32_t period;
bool valid = false;
if (fifo_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, fifo_nb);
valid = inv_update_chip_period(ts, fifo_mult, 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)sensor_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");
|
