voltage_divider.h

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/*
 * Copyright (c) 2023 The ChromiumOS Authors
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_
#define ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_
 
#include <zephyr/drivers/adc.h>
 
struct voltage_divider_dt_spec {
        const struct adc_dt_spec port;
        uint32_t full_ohms;
        uint32_t output_ohms;
};
 
#define VOLTAGE_DIVIDER_DT_SPEC_GET(node_id)                                                       \
        {                                                                                          \
                .port = ADC_DT_SPEC_GET(node_id),                                                  \
                .full_ohms = DT_PROP_OR(node_id, full_ohms, 0),                                    \
                .output_ohms = DT_PROP(node_id, output_ohms),                                      \
        }
 
static inline int voltage_divider_scale_dt(const struct voltage_divider_dt_spec *spec,
                                           int32_t *v_to_v)
{
        /* cannot be scaled if "full_ohms" is not specified */
        if (spec->full_ohms == 0) {
                return -ENOTSUP;
        }
 
        /* voltage scaled by voltage divider values using DT binding */
        *v_to_v = (int64_t)*v_to_v * spec->full_ohms / spec->output_ohms;
 
        return 0;
}
 
#endif /* ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_ */