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217 lines
5.9 KiB
217 lines
5.9 KiB
/* |
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* Copyright (c) 2020 The ZMK Contributors |
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* |
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* SPDX-License-Identifier: MIT |
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*/ |
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#define DT_DRV_COMPAT zmk_battery_voltage_divider |
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#include <device.h> |
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#include <drivers/gpio.h> |
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#include <drivers/adc.h> |
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#include <drivers/sensor.h> |
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#include <logging/log.h> |
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LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL); |
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struct io_channel_config { |
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const char *label; |
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uint8_t channel; |
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}; |
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struct gpio_channel_config { |
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const char *label; |
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uint8_t pin; |
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uint8_t flags; |
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}; |
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struct bvd_config { |
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struct io_channel_config io_channel; |
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struct gpio_channel_config power_gpios; |
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uint32_t output_ohm; |
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uint32_t full_ohm; |
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}; |
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struct bvd_data { |
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struct device *adc; |
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struct device *gpio; |
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struct adc_channel_cfg acc; |
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struct adc_sequence as; |
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uint16_t adc_raw; |
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uint16_t voltage; |
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uint8_t state_of_charge; |
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}; |
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static uint8_t lithium_ion_mv_to_pct(int16_t bat_mv) { |
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// Simple linear approximation of a battery based off adafruit's discharge graph: |
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// https://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages |
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if (bat_mv >= 4200) { |
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return 100; |
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} else if (bat_mv <= 3450) { |
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return 0; |
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} |
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return bat_mv * 2 / 15 - 459; |
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} |
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static int bvd_sample_fetch(struct device *dev, enum sensor_channel chan) { |
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struct bvd_data *drv_data = dev->data; |
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const struct bvd_config *drv_cfg = dev->config; |
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struct adc_sequence *as = &drv_data->as; |
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// Make sure selected channel is supported |
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if (chan != SENSOR_CHAN_GAUGE_VOLTAGE && chan != SENSOR_CHAN_GAUGE_STATE_OF_CHARGE && |
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chan != SENSOR_CHAN_ALL) { |
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LOG_DBG("Selected channel is not supported: %d.", chan); |
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return -ENOTSUP; |
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} |
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int rc = 0; |
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// Enable power GPIO if present |
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if (drv_data->gpio) { |
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rc = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 1); |
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if (rc != 0) { |
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LOG_DBG("Failed to enable ADC power GPIO: %d", rc); |
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return rc; |
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} |
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} |
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// Read ADC |
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rc = adc_read(drv_data->adc, as); |
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as->calibrate = false; |
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if (rc == 0) { |
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int32_t val = drv_data->adc_raw; |
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adc_raw_to_millivolts(adc_ref_internal(drv_data->adc), drv_data->acc.gain, as->resolution, |
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&val); |
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uint16_t millivolts = val * (uint64_t)drv_cfg->full_ohm / drv_cfg->output_ohm; |
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LOG_DBG("ADC raw %d ~ %d mV => %d mV\n", drv_data->adc_raw, val, millivolts); |
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uint8_t percent = lithium_ion_mv_to_pct(millivolts); |
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LOG_DBG("Percent: %d", percent); |
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drv_data->voltage = millivolts; |
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drv_data->state_of_charge = percent; |
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} else { |
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LOG_DBG("Failed to read ADC: %d", rc); |
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} |
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// Disable power GPIO if present |
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if (drv_data->gpio) { |
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int rc2 = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 0); |
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if (rc2 != 0) { |
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LOG_DBG("Failed to disable ADC power GPIO: %d", rc2); |
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return rc2; |
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} |
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} |
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return rc; |
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} |
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static int bvd_channel_get(struct device *dev, enum sensor_channel chan, struct sensor_value *val) { |
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struct bvd_data *drv_data = dev->data; |
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switch (chan) { |
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case SENSOR_CHAN_GAUGE_VOLTAGE: |
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val->val1 = drv_data->voltage / 1000; |
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val->val2 = (drv_data->voltage % 1000) * 1000U; |
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break; |
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case SENSOR_CHAN_GAUGE_STATE_OF_CHARGE: |
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val->val1 = drv_data->state_of_charge; |
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val->val2 = 0; |
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break; |
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default: |
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return -ENOTSUP; |
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} |
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return 0; |
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} |
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static const struct sensor_driver_api bvd_api = { |
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.sample_fetch = bvd_sample_fetch, |
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.channel_get = bvd_channel_get, |
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}; |
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static int bvd_init(struct device *dev) { |
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struct bvd_data *drv_data = dev->data; |
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const struct bvd_config *drv_cfg = dev->config; |
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drv_data->adc = device_get_binding(drv_cfg->io_channel.label); |
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if (drv_data->adc == NULL) { |
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LOG_ERR("ADC %s failed to retrieve", drv_cfg->io_channel.label); |
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return -ENODEV; |
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} |
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int rc = 0; |
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if (drv_cfg->power_gpios.label) { |
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drv_data->gpio = device_get_binding(drv_cfg->power_gpios.label); |
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if (drv_data->gpio == NULL) { |
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LOG_ERR("Failed to get GPIO %s", drv_cfg->power_gpios.label); |
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return -ENODEV; |
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} |
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rc = gpio_pin_configure(drv_data->gpio, drv_cfg->power_gpios.pin, |
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GPIO_OUTPUT_INACTIVE | drv_cfg->power_gpios.flags); |
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if (rc != 0) { |
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LOG_ERR("Failed to control feed %s.%u: %d", drv_cfg->power_gpios.label, |
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drv_cfg->power_gpios.pin, rc); |
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return rc; |
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} |
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} |
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drv_data->as = (struct adc_sequence){ |
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.channels = BIT(0), |
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.buffer = &drv_data->adc_raw, |
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.buffer_size = sizeof(drv_data->adc_raw), |
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.oversampling = 4, |
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.calibrate = true, |
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}; |
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#ifdef CONFIG_ADC_NRFX_SAADC |
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drv_data->acc = (struct adc_channel_cfg){ |
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.gain = ADC_GAIN_1_5, |
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.reference = ADC_REF_INTERNAL, |
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.acquisition_time = ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 40), |
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.input_positive = SAADC_CH_PSELP_PSELP_AnalogInput0 + drv_cfg->io_channel.channel, |
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}; |
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drv_data->as.resolution = 12; |
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#else |
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#error Unsupported ADC |
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#endif |
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rc = adc_channel_setup(drv_data->adc, &drv_data->acc); |
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LOG_DBG("AIN%u setup returned %d", drv_cfg->io_channel.channel, rc); |
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return rc; |
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} |
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static struct bvd_data bvd_data; |
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static const struct bvd_config bvd_cfg = { |
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.io_channel = |
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{ |
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DT_INST_IO_CHANNELS_LABEL(0), |
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DT_INST_IO_CHANNELS_INPUT(0), |
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}, |
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#if DT_INST_NODE_HAS_PROP(0, power_gpios) |
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.power_gpios = |
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{ |
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DT_INST_GPIO_LABEL(0, power_gpios), |
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DT_INST_GPIO_PIN(0, power_gpios), |
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DT_INST_GPIO_FLAGS(0, power_gpios), |
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}, |
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#endif |
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.output_ohm = DT_INST_PROP(0, output_ohms), |
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.full_ohm = DT_INST_PROP(0, full_ohms), |
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}; |
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DEVICE_AND_API_INIT(bvd_dev, DT_INST_LABEL(0), &bvd_init, &bvd_data, &bvd_cfg, POST_KERNEL, |
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CONFIG_SENSOR_INIT_PRIORITY, &bvd_api);
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