207 lines
6.2 KiB
C
207 lines
6.2 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-only */
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/* gain-time-scale conversion helpers for IIO light sensors
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*
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* Copyright (c) 2023 Matti Vaittinen <mazziesaccount@gmail.com>
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*/
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#ifndef __IIO_GTS_HELPER__
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#define __IIO_GTS_HELPER__
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#include <linux/types.h>
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struct device;
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/**
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* struct iio_gain_sel_pair - gain - selector values
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*
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* In many cases devices like light sensors allow setting signal amplification
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* (gain) using a register interface. This structure describes amplification
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* and corresponding selector (register value)
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*
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* @gain: Gain (multiplication) value. Gain must be positive, negative
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* values are reserved for error handling.
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* @sel: Selector (usually register value) used to indicate this gain.
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* NOTE: Only selectors >= 0 supported.
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*/
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struct iio_gain_sel_pair {
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int gain;
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int sel;
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};
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/**
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* struct iio_itime_sel_mul - integration time description
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*
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* In many cases devices like light sensors allow setting the duration of
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* collecting data. Typically this duration has also an impact to the magnitude
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* of measured values (gain). This structure describes the relation of
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* integration time and amplification as well as corresponding selector
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* (register value).
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*
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* An example could be a sensor allowing 50, 100, 200 and 400 mS times. The
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* respective multiplication values could be 50 mS => 1, 100 mS => 2,
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* 200 mS => 4 and 400 mS => 8 assuming the impact of integration time would be
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* linear in a way that when collecting data for 50 mS caused value X, doubling
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* the data collection time caused value 2X etc.
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*
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* @time_us: Integration time in microseconds. Time values must be positive,
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* negative values are reserved for error handling.
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* @sel: Selector (usually register value) used to indicate this time
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* NOTE: Only selectors >= 0 supported.
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* @mul: Multiplication to the values caused by this time.
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* NOTE: Only multipliers > 0 supported.
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*/
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struct iio_itime_sel_mul {
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int time_us;
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int sel;
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int mul;
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};
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struct iio_gts {
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u64 max_scale;
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const struct iio_gain_sel_pair *hwgain_table;
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int num_hwgain;
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const struct iio_itime_sel_mul *itime_table;
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int num_itime;
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int **per_time_avail_scale_tables;
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int *avail_all_scales_table;
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int num_avail_all_scales;
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int *avail_time_tables;
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int num_avail_time_tables;
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};
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#define GAIN_SCALE_GAIN(_gain, _sel) \
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{ \
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.gain = (_gain), \
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.sel = (_sel), \
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}
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#define GAIN_SCALE_ITIME_US(_itime, _sel, _mul) \
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{ \
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.time_us = (_itime), \
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.sel = (_sel), \
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.mul = (_mul), \
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}
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static inline const struct iio_itime_sel_mul *
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iio_gts_find_itime_by_time(struct iio_gts *gts, int time)
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{
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int i;
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if (!gts->num_itime)
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return NULL;
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for (i = 0; i < gts->num_itime; i++)
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if (gts->itime_table[i].time_us == time)
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return >s->itime_table[i];
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return NULL;
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}
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static inline const struct iio_itime_sel_mul *
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iio_gts_find_itime_by_sel(struct iio_gts *gts, int sel)
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{
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int i;
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for (i = 0; i < gts->num_itime; i++)
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if (gts->itime_table[i].sel == sel)
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return >s->itime_table[i];
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return NULL;
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}
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int devm_iio_init_iio_gts(struct device *dev, int max_scale_int, int max_scale_nano,
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const struct iio_gain_sel_pair *gain_tbl, int num_gain,
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const struct iio_itime_sel_mul *tim_tbl, int num_times,
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struct iio_gts *gts);
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/**
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* iio_gts_find_int_time_by_sel - find integration time matching a selector
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* @gts: Gain time scale descriptor
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* @sel: selector for which matching integration time is searched for
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*
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* Return: integration time matching given selector or -EINVAL if
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* integration time was not found.
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*/
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static inline int iio_gts_find_int_time_by_sel(struct iio_gts *gts, int sel)
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{
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const struct iio_itime_sel_mul *itime;
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itime = iio_gts_find_itime_by_sel(gts, sel);
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if (!itime)
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return -EINVAL;
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return itime->time_us;
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}
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/**
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* iio_gts_find_sel_by_int_time - find selector matching integration time
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* @gts: Gain time scale descriptor
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* @time: Integration time for which matching selector is searched for
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*
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* Return: a selector matching given integration time or -EINVAL if
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* selector was not found.
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*/
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static inline int iio_gts_find_sel_by_int_time(struct iio_gts *gts, int time)
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{
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const struct iio_itime_sel_mul *itime;
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itime = iio_gts_find_itime_by_time(gts, time);
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if (!itime)
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return -EINVAL;
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return itime->sel;
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}
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/**
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* iio_gts_valid_time - check if given integration time is valid
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* @gts: Gain time scale descriptor
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* @time_us: Integration time to check
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*
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* Return: True if given time is supported by device. False if not.
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*/
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static inline bool iio_gts_valid_time(struct iio_gts *gts, int time_us)
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{
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return iio_gts_find_itime_by_time(gts, time_us) != NULL;
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}
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int iio_gts_find_sel_by_gain(struct iio_gts *gts, int gain);
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/**
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* iio_gts_valid_gain - check if given HW-gain is valid
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* @gts: Gain time scale descriptor
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* @gain: HW-gain to check
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*
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* Return: True if given time is supported by device. False if not.
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*/
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static inline bool iio_gts_valid_gain(struct iio_gts *gts, int gain)
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{
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return iio_gts_find_sel_by_gain(gts, gain) >= 0;
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}
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int iio_find_closest_gain_low(struct iio_gts *gts, int gain, bool *in_range);
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int iio_gts_find_gain_by_sel(struct iio_gts *gts, int sel);
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int iio_gts_get_min_gain(struct iio_gts *gts);
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int iio_gts_find_int_time_by_sel(struct iio_gts *gts, int sel);
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int iio_gts_find_sel_by_int_time(struct iio_gts *gts, int time);
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int iio_gts_total_gain_to_scale(struct iio_gts *gts, int total_gain,
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int *scale_int, int *scale_nano);
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int iio_gts_find_gain_sel_for_scale_using_time(struct iio_gts *gts, int time_sel,
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int scale_int, int scale_nano,
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int *gain_sel);
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int iio_gts_get_scale(struct iio_gts *gts, int gain, int time, int *scale_int,
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int *scale_nano);
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int iio_gts_find_new_gain_sel_by_old_gain_time(struct iio_gts *gts,
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int old_gain, int old_time_sel,
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int new_time_sel, int *new_gain);
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int iio_gts_find_new_gain_by_old_gain_time(struct iio_gts *gts, int old_gain,
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int old_time, int new_time,
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int *new_gain);
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int iio_gts_avail_times(struct iio_gts *gts, const int **vals, int *type,
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int *length);
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int iio_gts_all_avail_scales(struct iio_gts *gts, const int **vals, int *type,
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int *length);
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int iio_gts_avail_scales_for_time(struct iio_gts *gts, int time,
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const int **vals, int *type, int *length);
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#endif
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