| /* |
| * Copyright (c) 2023 The ChromiumOS Authors |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| */ |
| |
| #ifndef ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_SHUNT_H_ |
| #define ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_SHUNT_H_ |
| |
| #include <zephyr/drivers/adc.h> |
| |
| struct current_sense_shunt_dt_spec { |
| const struct adc_dt_spec port; |
| uint32_t shunt_micro_ohms; |
| }; |
| |
| /** |
| * @brief Get current sensor information from devicetree. |
| * |
| * This returns a static initializer for a @p current_sense_shunt_dt_spec structure |
| * given a devicetree node. |
| * |
| * @param node_id Devicetree node identifier. |
| * |
| * @return Static initializer for an current_sense_shunt_dt_spec structure. |
| */ |
| #define CURRENT_SENSE_SHUNT_DT_SPEC_GET(node_id) \ |
| { \ |
| .port = ADC_DT_SPEC_GET(node_id), \ |
| .shunt_micro_ohms = DT_PROP(node_id, shunt_resistor_micro_ohms), \ |
| } |
| |
| /** |
| * @brief Calculates the actual amperage 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_shunt_scale_dt(const struct current_sense_shunt_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 shunt resistance in micro-ohms. */ |
| tmp = tmp * 1000000 / spec->shunt_micro_ohms; |
| |
| *v_to_i = (int32_t)tmp; |
| } |
| |
| #endif /* ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_SHUNT_H_ */ |