Hi, On Mon, Jan 26, 2026 at 09:09:49PM +0530, Kaustabh Chakraborty wrote: > From: Yassine Oudjana > > Samsung's S2MU005 PMIC, which contains battery charger functionality > also includes a battery fuel gauge device, which is separate from the > PMIC itself, and typically connected to an I2C bus. Add a generic driver > to support said device. > > Signed-off-by: Yassine Oudjana > Co-developed-by: Kaustabh Chakraborty > Signed-off-by: Kaustabh Chakraborty > --- > drivers/power/supply/Kconfig | 9 ++ > drivers/power/supply/Makefile | 1 + > drivers/power/supply/s2mu005-battery.c | 234 +++++++++++++++++++++++++++++++++ > 3 files changed, 244 insertions(+) > > diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig > index 92f9f7aae92f2..a5777309b1f62 100644 > --- a/drivers/power/supply/Kconfig > +++ b/drivers/power/supply/Kconfig > @@ -229,6 +229,15 @@ config BATTERY_SAMSUNG_SDI > Say Y to enable support for Samsung SDI battery data. > These batteries are used in Samsung mobile phones. > > +config BATTERY_S2MU005 > + tristate "Samsung S2MU005 PMIC fuel gauge driver" > + help > + Say Y to enable support for the Samsung S2MU005 PMIC integrated > + fuel gauge, which works indepenently of the PMIC battery charger > + counterpart, and reports battery metrics. > + > + This driver, if built as a module, will be called s2mu005-fuel-gauge. > + > config BATTERY_COLLIE > tristate "Sharp SL-5500 (collie) battery" > depends on SA1100_COLLIE && MCP_UCB1200 > diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile > index 4b79d5abc49a7..cd061887c1727 100644 > --- a/drivers/power/supply/Makefile > +++ b/drivers/power/supply/Makefile > @@ -40,6 +40,7 @@ obj-$(CONFIG_BATTERY_PMU) += pmu_battery.o > obj-$(CONFIG_BATTERY_QCOM_BATTMGR) += qcom_battmgr.o > obj-$(CONFIG_BATTERY_OLPC) += olpc_battery.o > obj-$(CONFIG_BATTERY_SAMSUNG_SDI) += samsung-sdi-battery.o > +obj-$(CONFIG_BATTERY_S2MU005) += s2mu005-battery.o > obj-$(CONFIG_BATTERY_COLLIE) += collie_battery.o > obj-$(CONFIG_BATTERY_INGENIC) += ingenic-battery.o > obj-$(CONFIG_BATTERY_INTEL_DC_TI) += intel_dc_ti_battery.o > diff --git a/drivers/power/supply/s2mu005-battery.c b/drivers/power/supply/s2mu005-battery.c > new file mode 100644 > index 0000000000000..914308e82683b > --- /dev/null > +++ b/drivers/power/supply/s2mu005-battery.c > @@ -0,0 +1,234 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Battery Fuel Gauge Driver for Samsung S2MU005 PMIC. > + * > + * Copyright (C) 2015 Samsung Electronics > + * Copyright (C) 2023 Yassine Oudjana > + * Copyright (C) 2025 Kaustabh Chakraborty > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define S2MU005_FG_REG_STATUS 0x00 > +#define S2MU005_FG_REG_IRQ 0x02 > +#define S2MU005_FG_REG_RVBAT 0x04 > +#define S2MU005_FG_REG_RCUR_CC 0x06 > +#define S2MU005_FG_REG_RSOC 0x08 > +#define S2MU005_FG_REG_MONOUT 0x0a > +#define S2MU005_FG_REG_MONOUT_SEL 0x0c > +#define S2MU005_FG_REG_RBATCAP 0x0e > +#define S2MU005_FG_REG_RZADJ 0x12 > +#define S2MU005_FG_REG_RBATZ0 0x16 > +#define S2MU005_FG_REG_RBATZ1 0x18 > +#define S2MU005_FG_REG_IRQ_LVL 0x1a > +#define S2MU005_FG_REG_START 0x1e > + > +struct s2mu005_fg { > + struct device *dev; > + struct regmap *regmap; > + struct power_supply *psy; > +}; > + > +static const struct regmap_config s2mu005_fg_regmap_config = { > + .reg_bits = 8, > + .val_bits = 8, > +}; Looks like all register addresses are 2 byte aligned and you are always using regmap_raw_read to get 16bit values. So just use .val_bits = 16 here? > +static irqreturn_t s2mu005_handle_irq(int irq, void *data) > +{ > + struct s2mu005_fg *priv = data; > + > + msleep(100); > + power_supply_changed(priv->psy); > + > + return IRQ_HANDLED; > +} > + > +static int s2mu005_fg_get_voltage_now(struct s2mu005_fg *priv, int *value) > +{ > + struct regmap *regmap = priv->regmap; > + u16 reg; > + int ret; > + > + ret = regmap_raw_read(regmap, S2MU005_FG_REG_RVBAT, ®, sizeof(reg)); > + if (ret < 0) { > + dev_err(priv->dev, "failed to read voltage register (%d)\n", ret); > + return ret; > + } > + > + *value = ((unsigned long)reg * 1000000) >> 13; /* uV */ > + > + return 0; > +} > + > +static int s2mu005_fg_get_current_now(struct s2mu005_fg *priv, int *value) > +{ > + struct regmap *regmap = priv->regmap; > + s16 reg; > + int ret; > + > + ret = regmap_raw_read(regmap, S2MU005_FG_REG_RCUR_CC, ®, sizeof(reg)); > + if (ret < 0) { > + dev_err(priv->dev, "failed to read current register (%d)\n", ret); > + return ret; > + } > + > + *value = -((long)reg * 1000000) >> 12; /* uA */ > + > + return 0; > +} > + > +static int s2mu005_fg_get_capacity(struct s2mu005_fg *priv, int *value) > +{ > + struct regmap *regmap = priv->regmap; > + s16 reg; > + int ret; > + > + ret = regmap_raw_read(regmap, S2MU005_FG_REG_RSOC, ®, sizeof(reg)); > + if (ret < 0) { > + dev_err(priv->dev, "failed to read capacity register (%d)\n", ret); > + return ret; > + } > + > + *value = (reg * 100) >> 14; /* percentage */ > + > + return 0; > +} > + > +static int s2mu005_fg_get_status(struct s2mu005_fg *priv, int *value) > +{ > + int current_now; > + int capacity; > + int ret; > + > + ret = s2mu005_fg_get_current_now(priv, ¤t_now); > + if (ret) > + return ret; > + > + if (current_now <= 0) { > + *value = POWER_SUPPLY_STATUS_DISCHARGING; > + return 0; > + } > + > + ret = s2mu005_fg_get_capacity(priv, &capacity); > + if (ret) > + return ret; > + > + if (capacity < 90) > + *value = POWER_SUPPLY_STATUS_CHARGING; > + else > + *value = POWER_SUPPLY_STATUS_FULL; Usually there is some kind of hysteresis that stops charging when the battery is full and then restarts charging once the battery drops under a certain capacity. As this code first checks the current to determine if the battery is discharging and only then checks if the battery is full - does your code toggle between FULL and DISCHARGING? > + return 0; > +} > + > +static const enum power_supply_property s2mu005_fg_properties[] = { > + POWER_SUPPLY_PROP_VOLTAGE_NOW, > + POWER_SUPPLY_PROP_CURRENT_NOW, > + POWER_SUPPLY_PROP_CAPACITY, > + POWER_SUPPLY_PROP_STATUS, > +}; > + > +static int s2mu005_fg_get_property(struct power_supply *psy, > + enum power_supply_property psp, > + union power_supply_propval *val) > +{ > + struct s2mu005_fg *priv = power_supply_get_drvdata(psy); > + int ret = 0; > + > + switch (psp) { > + case POWER_SUPPLY_PROP_VOLTAGE_NOW: > + ret = s2mu005_fg_get_voltage_now(priv, &val->intval); > + break; > + case POWER_SUPPLY_PROP_CURRENT_NOW: > + ret = s2mu005_fg_get_current_now(priv, &val->intval); > + break; > + case POWER_SUPPLY_PROP_CAPACITY: > + ret = s2mu005_fg_get_capacity(priv, &val->intval); > + break; > + case POWER_SUPPLY_PROP_STATUS: > + ret = s2mu005_fg_get_status(priv, &val->intval); > + break; > + default: > + return -EINVAL; > + } > + > + return ret; > +} > + > +static const struct power_supply_desc s2mu005_fg_desc = { > + .name = "s2mu005-fuel-gauge", > + .type = POWER_SUPPLY_TYPE_BATTERY, > + .properties = s2mu005_fg_properties, > + .num_properties = ARRAY_SIZE(s2mu005_fg_properties), > + .get_property = s2mu005_fg_get_property, > +}; > + > +static int s2mu005_fg_i2c_probe(struct i2c_client *client) > +{ > + struct device *dev = &client->dev; > + struct s2mu005_fg *priv; > + struct power_supply_config psy_cfg = {}; > + const struct power_supply_desc *psy_desc; > + int flags; > + int ret; > + > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return dev_err_probe(dev, -ENOMEM, > + "failed to allocate driver private\n"); Do not print error messages for -ENOMEM. > + > + dev_set_drvdata(dev, priv); > + priv->dev = dev; > + > + priv->regmap = devm_regmap_init_i2c(client, &s2mu005_fg_regmap_config); > + if (IS_ERR(priv->regmap)) > + return dev_err_probe(dev, PTR_ERR(priv->regmap), > + "failed to initialize regmap\n"); > + > + psy_desc = device_get_match_data(dev); > + > + psy_cfg.drv_data = priv; > + priv->psy = devm_power_supply_register(priv->dev, psy_desc, &psy_cfg); > + if (IS_ERR(priv->psy)) > + return dev_err_probe(dev, PTR_ERR(priv->psy), > + "failed to register power supply subsystem\n"); > + > + flags = irq_get_trigger_type(client->irq); This is not needed. By not specifying the trigger type the irq core code will do this internally. > + ret = devm_request_threaded_irq(priv->dev, client->irq, NULL, > + s2mu005_handle_irq, IRQF_ONESHOT | flags, > + psy_desc->name, priv); > + if (ret) > + dev_err_probe(dev, ret, "failed to request IRQ\n"); > + > + return 0; > +} > + > +static const struct of_device_id s2mu005_fg_of_match_table[] = { > + { > + .compatible = "samsung,s2mu005-fuel-gauge", > + .data = &s2mu005_fg_desc, > + }, { }, Please put the terminator into its own line and remove the final , > +}; > +MODULE_DEVICE_TABLE(of, s2mu005_fg_of_match_table); > + > +static struct i2c_driver s2mu005_fg_i2c_driver = { > + .probe = s2mu005_fg_i2c_probe, > + .driver = { > + .name = "s2mu005-fuel-gauge", > + .of_match_table = of_match_ptr(s2mu005_fg_of_match_table), Remove of_match_ptr(). > + }, > +}; > +module_i2c_driver(s2mu005_fg_i2c_driver); > + > +MODULE_DESCRIPTION("Samsung S2MU005 PMIC Battery Fuel Gauge Driver"); > +MODULE_AUTHOR("Yassine Oudjana "); > +MODULE_AUTHOR("Kaustabh Chakraborty "); > +MODULE_LICENSE("GPL"); Greetings, -- Sebastian