diff options
Diffstat (limited to 'drivers/power/supply/ug3105_battery.c')
| -rw-r--r-- | drivers/power/supply/ug3105_battery.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/power/supply/ug3105_battery.c b/drivers/power/supply/ug3105_battery.c new file mode 100644 index 000000000000..210e0f9aa5e0 --- /dev/null +++ b/drivers/power/supply/ug3105_battery.c @@ -0,0 +1,217 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Battery monitor driver for the uPI uG3105 battery monitor + * + * Note the uG3105 is not a full-featured autonomous fuel-gauge. Instead it is + * expected to be use in combination with some always on microcontroller reading + * its coulomb-counter before it can wrap (must be read every 400 seconds!). + * + * Since Linux does not monitor coulomb-counter changes while the device + * is off or suspended, the coulomb counter is not used atm. + * + * Possible improvements: + * 1. Add coulumb counter reading, e.g. something like this: + * Read + reset coulomb counter every 10 polls (every 300 seconds) + * + * if ((chip->poll_count % 10) == 0) { + * val = ug3105_read_word(chip->client, UG3105_REG_COULOMB_CNT); + * if (val < 0) + * goto out; + * + * i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1, + * UG3105_CTRL1_RESET_COULOMB_CNT); + * + * chip->total_coulomb_count += (s16)val; + * dev_dbg(&chip->client->dev, "coulomb count %d total %d\n", + * (s16)val, chip->total_coulomb_count); + * } + * + * 2. Reset total_coulomb_count val to 0 when the battery is as good as empty + * and remember that we did this (and clear the flag for this on susp/resume) + * 3. When the battery is full check if the flag that we set total_coulomb_count + * to when the battery was empty is set. If so we now know the capacity, + * not the design, but actual capacity, of the battery + * 4. Add some mechanism (needs userspace help, or maybe use efivar?) to remember + * the actual capacity of the battery over reboots + * 5. When we know the actual capacity at probe time, add energy_now and + * energy_full attributes. Guess boot + resume energy_now value based on ocv + * and then use total_coulomb_count to report energy_now over time, resetting + * things to adjust for drift when empty/full. This should give more accurate + * readings, esp. in the 30-70% range and allow userspace to estimate time + * remaining till empty/full + * 6. Maybe unregister + reregister the psy device when we learn the actual + * capacity during run-time ? + * + * The above will also require some sort of mwh_per_unit calculation. Testing + * has shown that an estimated 7404mWh increase of the battery's energy results + * in a total_coulomb_count increase of 3277 units with a 5 milli-ohm sense R. + * + * Copyright (C) 2021 - 2025 Hans de Goede <hansg@kernel.org> + */ + +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/i2c.h> +#include <linux/mod_devicetable.h> +#include <linux/power_supply.h> + +#include "adc-battery-helper.h" + +#define UG3105_REG_MODE 0x00 +#define UG3105_REG_CTRL1 0x01 +#define UG3105_REG_COULOMB_CNT 0x02 +#define UG3105_REG_BAT_VOLT 0x08 +#define UG3105_REG_BAT_CURR 0x0c + +#define UG3105_MODE_STANDBY 0x00 +#define UG3105_MODE_RUN 0x10 + +#define UG3105_CTRL1_RESET_COULOMB_CNT 0x03 + +struct ug3105_chip { + /* Must be the first member see adc-battery-helper documentation */ + struct adc_battery_helper helper; + struct i2c_client *client; + struct power_supply *psy; + int uv_per_unit; + int ua_per_unit; +}; + +static int ug3105_read_word(struct i2c_client *client, u8 reg) +{ + int val; + + val = i2c_smbus_read_word_data(client, reg); + if (val < 0) + dev_err(&client->dev, "Error reading reg 0x%02x\n", reg); + + return val; +} + +static int ug3105_get_voltage_and_current_now(struct power_supply *psy, int *volt, int *curr) +{ + struct ug3105_chip *chip = power_supply_get_drvdata(psy); + int ret; + + ret = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT); + if (ret < 0) + return ret; + + *volt = ret * chip->uv_per_unit; + + ret = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR); + if (ret < 0) + return ret; + + *curr = (s16)ret * chip->ua_per_unit; + return 0; +} + +static const struct power_supply_desc ug3105_psy_desc = { + .name = "ug3105_battery", + .type = POWER_SUPPLY_TYPE_BATTERY, + .get_property = adc_battery_helper_get_property, + .external_power_changed = adc_battery_helper_external_power_changed, + .properties = adc_battery_helper_properties, + .num_properties = ADC_HELPER_NUM_PROPERTIES, +}; + +static void ug3105_start(struct i2c_client *client) +{ + i2c_smbus_write_byte_data(client, UG3105_REG_MODE, UG3105_MODE_RUN); + i2c_smbus_write_byte_data(client, UG3105_REG_CTRL1, UG3105_CTRL1_RESET_COULOMB_CNT); +} + +static void ug3105_stop(struct i2c_client *client) +{ + i2c_smbus_write_byte_data(client, UG3105_REG_MODE, UG3105_MODE_STANDBY); +} + +static int ug3105_probe(struct i2c_client *client) +{ + struct power_supply_config psy_cfg = {}; + struct device *dev = &client->dev; + u32 curr_sense_res_uohm = 10000; + struct ug3105_chip *chip; + int ret; + + chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + chip->client = client; + + ug3105_start(client); + + device_property_read_u32(dev, "upisemi,rsns-microohm", &curr_sense_res_uohm); + + /* + * DAC maximum is 4.5V divided by 65536 steps + an unknown factor of 10 + * coming from somewhere for some reason (verified with a volt-meter). + */ + chip->uv_per_unit = 45000000 / 65536; + /* Datasheet says 8.1 uV per unit for the current ADC */ + chip->ua_per_unit = 8100000 / curr_sense_res_uohm; + + psy_cfg.drv_data = chip; + chip->psy = devm_power_supply_register(dev, &ug3105_psy_desc, &psy_cfg); + if (IS_ERR(chip->psy)) { + ret = PTR_ERR(chip->psy); + goto stop; + } + + ret = adc_battery_helper_init(&chip->helper, chip->psy, + ug3105_get_voltage_and_current_now, NULL); + if (ret) + goto stop; + + i2c_set_clientdata(client, chip); + return 0; + +stop: + ug3105_stop(client); + return ret; +} + +static int __maybe_unused ug3105_suspend(struct device *dev) +{ + struct ug3105_chip *chip = dev_get_drvdata(dev); + + adc_battery_helper_suspend(dev); + ug3105_stop(chip->client); + return 0; +} + +static int __maybe_unused ug3105_resume(struct device *dev) +{ + struct ug3105_chip *chip = dev_get_drvdata(dev); + + ug3105_start(chip->client); + adc_battery_helper_resume(dev); + return 0; +} + +static SIMPLE_DEV_PM_OPS(ug3105_pm_ops, ug3105_suspend, + ug3105_resume); + +static const struct i2c_device_id ug3105_id[] = { + { "ug3105" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ug3105_id); + +static struct i2c_driver ug3105_i2c_driver = { + .driver = { + .name = "ug3105", + .pm = &ug3105_pm_ops, + }, + .probe = ug3105_probe, + .remove = ug3105_stop, + .shutdown = ug3105_stop, + .id_table = ug3105_id, +}; +module_i2c_driver(ug3105_i2c_driver); + +MODULE_AUTHOR("Hans de Goede <hansg@kernel.org"); +MODULE_DESCRIPTION("uPI uG3105 battery monitor driver"); +MODULE_LICENSE("GPL"); |