// 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. Activate commented out total_coulomb_count code
* 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 Hans de Goede <[email protected]>
*/
#include <linux/devm-helpers.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/mod_devicetable.h>
#include <linux/power_supply.h>
#include <linux/workqueue.h>
#define UG3105_MOV_AVG_WINDOW 8
#define UG3105_INIT_POLL_TIME (5 * HZ)
#define UG3105_POLL_TIME (30 * HZ)
#define UG3105_SETTLE_TIME (1 * HZ)
#define UG3105_INIT_POLL_COUNT 30
#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
#define UG3105_CURR_HYST_UA 65000
#define UG3105_LOW_BAT_UV 3700000
#define UG3105_FULL_BAT_HYST_UV 38000
struct ug3105_chip {
struct i2c_client *client;
struct power_supply *psy;
struct power_supply_battery_info *info;
struct delayed_work work;
struct mutex lock;
int ocv[UG3105_MOV_AVG_WINDOW]; /* micro-volt */
int intern_res[UG3105_MOV_AVG_WINDOW]; /* milli-ohm */
int poll_count;
int ocv_avg_index;
int ocv_avg; /* micro-volt */
int intern_res_poll_count;
int intern_res_avg_index;
int intern_res_avg; /* milli-ohm */
int volt; /* micro-volt */
int curr; /* micro-ampere */
int total_coulomb_count;
int uv_per_unit;
int ua_per_unit;
int status;
int capacity;
bool supplied;
};
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_status(struct ug3105_chip *chip)
{
int full = chip->info->constant_charge_voltage_max_uv - UG3105_FULL_BAT_HYST_UV;
if (chip->curr > UG3105_CURR_HYST_UA)
return POWER_SUPPLY_STATUS_CHARGING;
if (chip->curr < -UG3105_CURR_HYST_UA)
return POWER_SUPPLY_STATUS_DISCHARGING;
if (chip->supplied && chip->ocv_avg > full)
return POWER_SUPPLY_STATUS_FULL;
return POWER_SUPPLY_STATUS_NOT_CHARGING;
}
static int ug3105_get_capacity(struct ug3105_chip *chip)
{
/*
* OCV voltages in uV for 0-110% in 5% increments, the 100-110% is
* for LiPo HV (High-Voltage) bateries which can go up to 4.35V
* instead of the usual 4.2V.
*/
static const int ocv_capacity_tbl[23] = {
3350000,
3610000,
3690000,
3710000,
3730000,
3750000,
3770000,
3786667,
3803333,
3820000,
3836667,
3853333,
3870000,
3907500,
3945000,
3982500,
4020000,
4075000,
4110000,
4150000,
4200000,
4250000,
4300000,
};
int i, ocv_diff, ocv_step;
if (chip->ocv_avg < ocv_capacity_tbl[0])
return 0;
if (chip->status == POWER_SUPPLY_STATUS_FULL)
return 100;
for (i = 1; i < ARRAY_SIZE(ocv_capacity_tbl); i++) {
if (chip->ocv_avg > ocv_capacity_tbl[i])
continue;
ocv_diff = ocv_capacity_tbl[i] - chip->ocv_avg;
ocv_step = ocv_capacity_tbl[i] - ocv_capacity_tbl[i - 1];
/* scale 0-110% down to 0-100% for LiPo HV */
if (chip->info->constant_charge_voltage_max_uv >= 4300000)
return (i * 500 - ocv_diff * 500 / ocv_step) / 110;
else
return i * 5 - ocv_diff * 5 / ocv_step;
}
return 100;
}
static void ug3105_work(struct work_struct *work)
{
struct ug3105_chip *chip = container_of(work, struct ug3105_chip,
work.work);
int i, val, curr_diff, volt_diff, res, win_size;
bool prev_supplied = chip->supplied;
int prev_status = chip->status;
int prev_volt = chip->volt;
int prev_curr = chip->curr;
struct power_supply *psy;
mutex_lock(&chip->lock);
psy = chip->psy;
if (!psy)
goto out;
val = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT);
if (val < 0)
goto out;
chip->volt = val * chip->uv_per_unit;
val = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR);
if (val < 0)
goto out;
chip->curr = (s16)val * chip->ua_per_unit;
chip->ocv[chip->ocv_avg_index] =
chip->volt - chip->curr * chip->intern_res_avg / 1000;
chip->ocv_avg_index = (chip->ocv_avg_index + 1) % UG3105_MOV_AVG_WINDOW;
chip->poll_count++;
/*
* See possible improvements comment above.
*
* 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);
* }
*/
chip->ocv_avg = 0;
win_size = min(chip->poll_count, UG3105_MOV_AVG_WINDOW);
for (i = 0; i < win_size; i++)
chip->ocv_avg += chip->ocv[i];
chip->ocv_avg /= win_size;
chip->supplied = power_supply_am_i_supplied(psy);
chip->status = ug3105_get_status(chip);
chip->capacity = ug3105_get_capacity(chip);
/*
* Skip internal resistance calc on charger [un]plug and
* when the battery is almost empty (voltage low).
*/
if (chip->supplied != prev_supplied ||
chip->volt < UG3105_LOW_BAT_UV ||
chip->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 = abs(chip->curr - prev_curr);
if (curr_diff < UG3105_CURR_HYST_UA)
goto out;
volt_diff = abs(chip->volt - prev_volt);
res = volt_diff * 1000 / curr_diff;
if ((res < (chip->intern_res_avg * 2 / 3)) ||
(res > (chip->intern_res_avg * 4 / 3))) {
dev_dbg(&chip->client->dev, "Ignoring outlier internal resistance %d mOhm\n", res);
goto out;
}
dev_dbg(&chip->client->dev, "Internal resistance %d mOhm\n", res);
chip->intern_res[chip->intern_res_avg_index] = res;
chip->intern_res_avg_index = (chip->intern_res_avg_index + 1) % UG3105_MOV_AVG_WINDOW;
chip->intern_res_poll_count++;
chip->intern_res_avg = 0;
win_size = min(chip->intern_res_poll_count, UG3105_MOV_AVG_WINDOW);
for (i = 0; i < win_size; i++)
chip->intern_res_avg += chip->intern_res[i];
chip->intern_res_avg /= win_size;
out:
mutex_unlock(&chip->lock);
queue_delayed_work(system_wq, &chip->work,
(chip->poll_count <= UG3105_INIT_POLL_COUNT) ?
UG3105_INIT_POLL_TIME : UG3105_POLL_TIME);
if (chip->status != prev_status && psy)
power_supply_changed(psy);
}
static enum power_supply_property ug3105_battery_props[] = {
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_PRESENT,
POWER_SUPPLY_PROP_TECHNOLOGY,
POWER_SUPPLY_PROP_SCOPE,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
POWER_SUPPLY_PROP_VOLTAGE_OCV,
POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_CAPACITY,
};
static int ug3105_get_property(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val)
{
struct ug3105_chip *chip = power_supply_get_drvdata(psy);
int ret = 0;
mutex_lock(&chip->lock);
if (!chip->psy) {
ret = -EAGAIN;
goto out;
}
switch (psp) {
case POWER_SUPPLY_PROP_STATUS:
val->intval = chip->status;
break;
case POWER_SUPPLY_PROP_PRESENT:
val->intval = 1;
break;
case POWER_SUPPLY_PROP_TECHNOLOGY:
val->intval = chip->info->technology;
break;
case POWER_SUPPLY_PROP_SCOPE:
val->intval = POWER_SUPPLY_SCOPE_SYSTEM;
break;
case POWER_SUPPLY_PROP_VOLTAGE_NOW:
ret = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT);
if (ret < 0)
break;
val->intval = ret * chip->uv_per_unit;
ret = 0;
break;
case POWER_SUPPLY_PROP_VOLTAGE_OCV:
val->intval = chip->ocv_avg;
break;
case POWER_SUPPLY_PROP_CURRENT_NOW:
ret = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR);
if (ret < 0)
break;
val->intval = (s16)ret * chip->ua_per_unit;
ret = 0;
break;
case POWER_SUPPLY_PROP_CAPACITY:
val->intval = chip->capacity;
break;
default:
ret = -EINVAL;
}
out:
mutex_unlock(&chip->lock);
return ret;
}
static void ug3105_external_power_changed(struct power_supply *psy)
{
struct ug3105_chip *chip = power_supply_get_drvdata(psy);
dev_dbg(&chip->client->dev, "external power changed\n");
mod_delayed_work(system_wq, &chip->work, UG3105_SETTLE_TIME);
}
static const struct power_supply_desc ug3105_psy_desc = {
.name = "ug3105_battery",
.type = POWER_SUPPLY_TYPE_BATTERY,
.get_property = ug3105_get_property,
.external_power_changed = ug3105_external_power_changed,
.properties = ug3105_battery_props,
.num_properties = ARRAY_SIZE(ug3105_battery_props),
};
static void ug3105_init(struct ug3105_chip *chip)
{
chip->poll_count = 0;
chip->ocv_avg_index = 0;
chip->total_coulomb_count = 0;
i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE,
UG3105_MODE_RUN);
i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1,
UG3105_CTRL1_RESET_COULOMB_CNT);
queue_delayed_work(system_wq, &chip->work, 0);
flush_delayed_work(&chip->work);
}
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 power_supply *psy;
struct ug3105_chip *chip;
int ret;
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
chip->client = client;
mutex_init(&chip->lock);
ret = devm_delayed_work_autocancel(dev, &chip->work, ug3105_work);
if (ret)
return ret;
psy_cfg.drv_data = chip;
psy = devm_power_supply_register(dev, &ug3105_psy_desc, &psy_cfg);
if (IS_ERR(psy))
return PTR_ERR(psy);
ret = power_supply_get_battery_info(psy, &chip->info);
if (ret)
return ret;
if (chip->info->factory_internal_resistance_uohm == -EINVAL ||
chip->info->constant_charge_voltage_max_uv == -EINVAL) {
dev_err(dev, "error required properties are missing\n");
return -ENODEV;
}
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;
/* Use provided internal resistance as start point (in milli-ohm) */
chip->intern_res_avg = chip->info->factory_internal_resistance_uohm / 1000;
/* Also add it to the internal resistance moving average window */
chip->intern_res[0] = chip->intern_res_avg;
chip->intern_res_avg_index = 1;
chip->intern_res_poll_count = 1;
mutex_lock(&chip->lock);
chip->psy = psy;
mutex_unlock(&chip->lock);
ug3105_init(chip);
i2c_set_clientdata(client, chip);
return 0;
}
static int __maybe_unused ug3105_suspend(struct device *dev)
{
struct ug3105_chip *chip = dev_get_drvdata(dev);
cancel_delayed_work_sync(&chip->work);
i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE,
UG3105_MODE_STANDBY);
return 0;
}
static int __maybe_unused ug3105_resume(struct device *dev)
{
struct ug3105_chip *chip = dev_get_drvdata(dev);
ug3105_init(chip);
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,
.id_table = ug3105_id,
};
module_i2c_driver(ug3105_i2c_driver);
MODULE_AUTHOR("Hans de Goede <[email protected]");
MODULE_DESCRIPTION("uPI uG3105 battery monitor driver");
MODULE_LICENSE("GPL");
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