diff options
Diffstat (limited to 'drivers/power/supply/adc-battery-helper.c')
| -rw-r--r-- | drivers/power/supply/adc-battery-helper.c | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/drivers/power/supply/adc-battery-helper.c b/drivers/power/supply/adc-battery-helper.c new file mode 100644 index 000000000000..6e0f5b6d73d7 --- /dev/null +++ b/drivers/power/supply/adc-battery-helper.c @@ -0,0 +1,327 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Helper for batteries with accurate current and voltage measurement, but + * without temperature measurement or without a "resistance-temp-table". + * + * Some fuel-gauges are not full-featured autonomous fuel-gauges. + * These fuel-gauges offer accurate current and voltage measurements but + * their coulomb-counters are intended to work together with an always on + * micro-controller monitoring the fuel-gauge. + * + * This adc-battery-helper code offers open-circuit-voltage (ocv) and through + * that capacity estimation for devices where such limited functionality + * fuel-gauges are exposed directly to Linux. + * + * This helper requires the hw to provide accurate battery current_now and + * voltage_now measurement and this helper the provides the following properties + * based on top of those readings: + * + * POWER_SUPPLY_PROP_STATUS + * POWER_SUPPLY_PROP_VOLTAGE_OCV + * POWER_SUPPLY_PROP_VOLTAGE_NOW + * POWER_SUPPLY_PROP_CURRENT_NOW + * POWER_SUPPLY_PROP_CAPACITY + * + * As well as optional the following properties assuming an always present + * system-scope battery, allowing direct use of adc_battery_helper_get_prop() + * in this common case: + * POWER_SUPPLY_PROP_PRESENT + * POWER_SUPPLY_PROP_SCOPE + * + * Using this helper is as simple as: + * + * 1. Embed a struct adc_battery_helper this MUST be the first member of + * the battery driver's data struct. + * 2. Use adc_battery_helper_props[] or add the above properties to + * the list of properties in power_supply_desc + * 3. Call adc_battery_helper_init() after registering the power_supply and + * before returning from the probe() function + * 4. Use adc_battery_helper_get_prop() as the power-supply's get_property() + * method, or call it for the above properties. + * 5. Use adc_battery_helper_external_power_changed() as the power-supply's + * external_power_changed() method or call it from that method. + * 6. Use adc_battery_helper_[suspend|resume]() as suspend-resume methods or + * call them from the driver's suspend-resume methods. + * + * The provided get_voltage_and_current_now() method will be called by this + * helper at adc_battery_helper_init() time and later. + * + * Copyright (c) 2021-2025 Hans de Goede <hansg@kernel.org> + */ + +#include <linux/cleanup.h> +#include <linux/devm-helpers.h> +#include <linux/gpio/consumer.h> +#include <linux/mutex.h> +#include <linux/power_supply.h> +#include <linux/workqueue.h> + +#include "adc-battery-helper.h" + +#define MOV_AVG_WINDOW_SIZE ADC_BAT_HELPER_MOV_AVG_WINDOW_SIZE +#define INIT_POLL_TIME (5 * HZ) +#define POLL_TIME (30 * HZ) +#define SETTLE_TIME (1 * HZ) + +#define INIT_POLL_COUNT 30 + +#define CURR_HYST_UA 65000 + +#define LOW_BAT_UV 3700000 +#define FULL_BAT_HYST_UV 38000 + +#define AMBIENT_TEMP_CELSIUS 25 + +static int adc_battery_helper_get_status(struct adc_battery_helper *help) +{ + int full_uv = + help->psy->battery_info->constant_charge_voltage_max_uv - FULL_BAT_HYST_UV; + + if (help->curr_ua > CURR_HYST_UA) + return POWER_SUPPLY_STATUS_CHARGING; + + if (help->curr_ua < -CURR_HYST_UA) + return POWER_SUPPLY_STATUS_DISCHARGING; + + if (help->supplied) { + bool full; + + if (help->charge_finished) + full = gpiod_get_value_cansleep(help->charge_finished); + else + full = help->ocv_avg_uv > full_uv; + + if (full) + return POWER_SUPPLY_STATUS_FULL; + } + + return POWER_SUPPLY_STATUS_NOT_CHARGING; +} + +static void adc_battery_helper_work(struct work_struct *work) +{ + struct adc_battery_helper *help = container_of(work, struct adc_battery_helper, + work.work); + int i, curr_diff_ua, volt_diff_uv, res_mohm, ret, win_size; + struct device *dev = help->psy->dev.parent; + int volt_uv, prev_volt_uv = help->volt_uv; + int curr_ua, prev_curr_ua = help->curr_ua; + bool prev_supplied = help->supplied; + int prev_status = help->status; + + guard(mutex)(&help->lock); + + ret = help->get_voltage_and_current_now(help->psy, &volt_uv, &curr_ua); + if (ret) + goto out; + + help->volt_uv = volt_uv; + help->curr_ua = curr_ua; + + help->ocv_uv[help->ocv_avg_index] = + help->volt_uv - help->curr_ua * help->intern_res_avg_mohm / 1000; + dev_dbg(dev, "volt-now: %d, curr-now: %d, volt-ocv: %d\n", + help->volt_uv, help->curr_ua, help->ocv_uv[help->ocv_avg_index]); + help->ocv_avg_index = (help->ocv_avg_index + 1) % MOV_AVG_WINDOW_SIZE; + help->poll_count++; + + help->ocv_avg_uv = 0; + win_size = min(help->poll_count, MOV_AVG_WINDOW_SIZE); + for (i = 0; i < win_size; i++) + help->ocv_avg_uv += help->ocv_uv[i]; + help->ocv_avg_uv /= win_size; + + help->supplied = power_supply_am_i_supplied(help->psy); + help->status = adc_battery_helper_get_status(help); + if (help->status == POWER_SUPPLY_STATUS_FULL) + help->capacity = 100; + else + help->capacity = power_supply_batinfo_ocv2cap(help->psy->battery_info, + help->ocv_avg_uv, + AMBIENT_TEMP_CELSIUS); + + /* + * Skip internal resistance calc on charger [un]plug and + * when the battery is almost empty (voltage low). + */ + if (help->supplied != prev_supplied || + help->volt_uv < LOW_BAT_UV || + help->poll_count < 2) + goto out; + + /* + * Assuming that the OCV voltage does not change significantly + * between 2 polls, then we can calculate the internal resistance + * on a significant current change by attributing all voltage + * change between the 2 readings to the internal resistance. + */ + curr_diff_ua = abs(help->curr_ua - prev_curr_ua); + if (curr_diff_ua < CURR_HYST_UA) + goto out; + + volt_diff_uv = abs(help->volt_uv - prev_volt_uv); + res_mohm = volt_diff_uv * 1000 / curr_diff_ua; + + if ((res_mohm < (help->intern_res_avg_mohm * 2 / 3)) || + (res_mohm > (help->intern_res_avg_mohm * 4 / 3))) { + dev_dbg(dev, "Ignoring outlier internal resistance %d mOhm\n", res_mohm); + goto out; + } + + dev_dbg(dev, "Internal resistance %d mOhm\n", res_mohm); + + help->intern_res_mohm[help->intern_res_avg_index] = res_mohm; + help->intern_res_avg_index = (help->intern_res_avg_index + 1) % MOV_AVG_WINDOW_SIZE; + help->intern_res_poll_count++; + + help->intern_res_avg_mohm = 0; + win_size = min(help->intern_res_poll_count, MOV_AVG_WINDOW_SIZE); + for (i = 0; i < win_size; i++) + help->intern_res_avg_mohm += help->intern_res_mohm[i]; + help->intern_res_avg_mohm /= win_size; + +out: + queue_delayed_work(system_percpu_wq, &help->work, + (help->poll_count <= INIT_POLL_COUNT) ? + INIT_POLL_TIME : POLL_TIME); + + if (help->status != prev_status) + power_supply_changed(help->psy); +} + +const enum power_supply_property adc_battery_helper_properties[] = { + POWER_SUPPLY_PROP_STATUS, + POWER_SUPPLY_PROP_VOLTAGE_NOW, + POWER_SUPPLY_PROP_VOLTAGE_OCV, + POWER_SUPPLY_PROP_CURRENT_NOW, + POWER_SUPPLY_PROP_CAPACITY, + POWER_SUPPLY_PROP_PRESENT, + POWER_SUPPLY_PROP_SCOPE, +}; +EXPORT_SYMBOL_GPL(adc_battery_helper_properties); + +static_assert(ARRAY_SIZE(adc_battery_helper_properties) == + ADC_HELPER_NUM_PROPERTIES); + +int adc_battery_helper_get_property(struct power_supply *psy, + enum power_supply_property psp, + union power_supply_propval *val) +{ + struct adc_battery_helper *help = power_supply_get_drvdata(psy); + int dummy, ret = 0; + + /* + * Avoid racing with adc_battery_helper_work() while it is updating + * variables and avoid calling get_voltage_and_current_now() reentrantly. + */ + guard(mutex)(&help->lock); + + switch (psp) { + case POWER_SUPPLY_PROP_STATUS: + val->intval = help->status; + break; + case POWER_SUPPLY_PROP_VOLTAGE_NOW: + ret = help->get_voltage_and_current_now(psy, &val->intval, &dummy); + break; + case POWER_SUPPLY_PROP_VOLTAGE_OCV: + val->intval = help->ocv_avg_uv; + break; + case POWER_SUPPLY_PROP_CURRENT_NOW: + ret = help->get_voltage_and_current_now(psy, &dummy, &val->intval); + break; + case POWER_SUPPLY_PROP_CAPACITY: + val->intval = help->capacity; + break; + case POWER_SUPPLY_PROP_PRESENT: + val->intval = 1; + break; + case POWER_SUPPLY_PROP_SCOPE: + val->intval = POWER_SUPPLY_SCOPE_SYSTEM; + break; + default: + return -EINVAL; + } + + return ret; +} +EXPORT_SYMBOL_GPL(adc_battery_helper_get_property); + +void adc_battery_helper_external_power_changed(struct power_supply *psy) +{ + struct adc_battery_helper *help = power_supply_get_drvdata(psy); + + dev_dbg(help->psy->dev.parent, "external power changed\n"); + mod_delayed_work(system_percpu_wq, &help->work, SETTLE_TIME); +} +EXPORT_SYMBOL_GPL(adc_battery_helper_external_power_changed); + +static void adc_battery_helper_start_work(struct adc_battery_helper *help) +{ + help->poll_count = 0; + help->ocv_avg_index = 0; + + queue_delayed_work(system_percpu_wq, &help->work, 0); + flush_delayed_work(&help->work); +} + +int adc_battery_helper_init(struct adc_battery_helper *help, struct power_supply *psy, + adc_battery_helper_get_func get_voltage_and_current_now, + struct gpio_desc *charge_finished_gpio) +{ + struct device *dev = psy->dev.parent; + int ret; + + help->psy = psy; + help->get_voltage_and_current_now = get_voltage_and_current_now; + help->charge_finished = charge_finished_gpio; + + ret = devm_mutex_init(dev, &help->lock); + if (ret) + return ret; + + ret = devm_delayed_work_autocancel(dev, &help->work, adc_battery_helper_work); + if (ret) + return ret; + + if (!help->psy->battery_info || + help->psy->battery_info->factory_internal_resistance_uohm == -EINVAL || + help->psy->battery_info->constant_charge_voltage_max_uv == -EINVAL || + !psy->battery_info->ocv_table[0]) { + dev_err(dev, "error required properties are missing\n"); + return -ENODEV; + } + + /* Use provided internal resistance as start point (in milli-ohm) */ + help->intern_res_avg_mohm = + help->psy->battery_info->factory_internal_resistance_uohm / 1000; + /* Also add it to the internal resistance moving average window */ + help->intern_res_mohm[0] = help->intern_res_avg_mohm; + help->intern_res_avg_index = 1; + help->intern_res_poll_count = 1; + + adc_battery_helper_start_work(help); + return 0; +} +EXPORT_SYMBOL_GPL(adc_battery_helper_init); + +int adc_battery_helper_suspend(struct device *dev) +{ + struct adc_battery_helper *help = dev_get_drvdata(dev); + + cancel_delayed_work_sync(&help->work); + return 0; +} +EXPORT_SYMBOL_GPL(adc_battery_helper_suspend); + +int adc_battery_helper_resume(struct device *dev) +{ + struct adc_battery_helper *help = dev_get_drvdata(dev); + + adc_battery_helper_start_work(help); + return 0; +} +EXPORT_SYMBOL_GPL(adc_battery_helper_resume); + +MODULE_AUTHOR("Hans de Goede <hansg@kernel.org>"); +MODULE_DESCRIPTION("ADC battery capacity estimation helper"); +MODULE_LICENSE("GPL"); |