Line data    Source code

       1           0 : /*
       2             :  * Copyright (c) 2023 The ChromiumOS Authors
       3             :  *
       4             :  * SPDX-License-Identifier: Apache-2.0
       5             :  */
       6             : 
       7             : #ifndef ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_
       8             : #define ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_
       9             : 
      10             : #include <zephyr/drivers/adc.h>
      11             : 
      12           0 : struct voltage_divider_dt_spec {
      13           0 :         const struct adc_dt_spec port;
      14           0 :         uint32_t full_ohms;
      15           0 :         uint32_t output_ohms;
      16             : };
      17             : 
      18             : /**
      19             :  * @brief Get voltage divider information from devicetree.
      20             :  *
      21             :  * This returns a static initializer for a @p voltage_divider_dt_spec structure
      22             :  * given a devicetree node.
      23             :  *
      24             :  * @param node_id Devicetree node identifier.
      25             :  *
      26             :  * @return Static initializer for an voltage_divider_dt_spec structure.
      27             :  */
      28           1 : #define VOLTAGE_DIVIDER_DT_SPEC_GET(node_id)                                                       \
      29             :         {                                                                                          \
      30             :                 .port = ADC_DT_SPEC_GET(node_id),                                                  \
      31             :                 .full_ohms = DT_PROP_OR(node_id, full_ohms, 0),                                    \
      32             :                 .output_ohms = DT_PROP(node_id, output_ohms),                                      \
      33             :         }
      34             : 
      35             : /**
      36             :  * @brief Calculates the actual voltage from the measured voltage
      37             :  *
      38             :  * @param[in] spec voltage divider specification from Devicetree.
      39             :  * @param[in,out] v_to_v Pointer to the measured voltage on input, and the
      40             :  * corresponding scaled voltage value on output.
      41             :  *
      42             :  * @retval 0 on success
      43             :  * @retval -ENOTSUP if "full_ohms" is not specified
      44             :  */
      45           1 : static inline int voltage_divider_scale_dt(const struct voltage_divider_dt_spec *spec,
      46             :                                            int32_t *v_to_v)
      47             : {
      48             :         /* cannot be scaled if "full_ohms" is not specified */
      49             :         if (spec->full_ohms == 0) {
      50             :                 return -ENOTSUP;
      51             :         }
      52             : 
      53             :         /* voltage scaled by voltage divider values using DT binding */
      54             :         *v_to_v = (int64_t)*v_to_v * spec->full_ohms / spec->output_ohms;
      55             : 
      56             :         return 0;
      57             : }
      58             : 
      59             : #endif /* ZEPHYR_INCLUDE_DRIVERS_ADC_VOLTAGE_DIVIDER_H_ */