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drivers: afe: current sense amplifier

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adds DT macro initializer and scaling function for current sense
amplifier.

Signed-off-by: Jason Yuan <jasonyuan@google.com>
This commit is contained in:
Jason Yuan 2023-03-23 13:43:03 -07:00 committed by Carles Cufí
parent fcb4c23b95
commit fe20701bd8
1 changed files with 57 additions and 0 deletions
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include/zephyr/drivers/adc/current_sense_amplifier.h Normal file
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/*
* Copyright (c) 2023 The ChromiumOS Authors
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifndef ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_
#define ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_
#include <zephyr/drivers/adc.h>
struct current_sense_amplifier_dt_spec {
const struct adc_dt_spec port;
uint32_t sense_micro_ohms;
uint32_t sense_gain_mult;
uint32_t sense_gain_div;
};
/**
* @brief Get current sensor information from devicetree.
*
* This returns a static initializer for a @p current_sense_amplifier_dt_spec structure
* given a devicetree node.
*
* @param node_id Devicetree node identifier.
*
* @return Static initializer for an current_sense_amplifier_dt_spec structure.
*/
#define CURRENT_SENSE_AMPLIFIER_DT_SPEC_GET(node_id) \
{ \
.port = ADC_DT_SPEC_GET(node_id), \
.sense_micro_ohms = DT_PROP(node_id, sense_resistor_micro_ohms), \
.sense_gain_mult = DT_PROP(node_id, sense_gain_mult), \
.sense_gain_div = DT_PROP(node_id, sense_gain_div), \
}
/**
* @brief Calculates the actual voltage from the measured voltage
*
* @param[in] spec current sensor specification from Devicetree.
* @param[in,out] v_to_i Pointer to the measured voltage in millivolts on input, and the
* corresponding scaled current value in milliamps on output.
*/
static inline void
current_sense_amplifier_scale_dt(const struct current_sense_amplifier_dt_spec *spec,
int32_t *v_to_i)
{
/* store in a temporary 64 bit variable to prevent overflow during calculation */
int64_t tmp = *v_to_i;
/* multiplies by 1,000,000 before dividing by sense resistance in micro-ohms. */
tmp = tmp * 1000000 / spec->sense_micro_ohms * spec->sense_gain_div / spec->sense_gain_mult;
*v_to_i = (int32_t)tmp;
}
#endif /* ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_ */