--- /dev/null
+// 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 <hdegoede@redhat.com>
+ */
+
+#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_new = ug3105_probe,
+ .id_table = ug3105_id,
+};
+module_i2c_driver(ug3105_i2c_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com");
+MODULE_DESCRIPTION("uPI uG3105 battery monitor driver");
+MODULE_LICENSE("GPL");
projects / platform / kernel / linux-starfive.git / commitdiff