Add driver for Maxim 77705 fuel gauge (part of max77705
MFD driver) providing power supply class information to userspace.

The driver is configured through DTS (battery and system related
settings).

Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com>

---
Changes for v5:
- fix license
- use same hardware name in Kconfig and module descriptions
- fix email, and module author

Changes for v4:
- rework driver from scratch
- change word delimiters in filenames to "_"
- remove debugfs code
- cleanup header
---
 drivers/power/supply/Kconfig               |   7 +++
 drivers/power/supply/Makefile              |   1 +
 drivers/power/supply/max77705_fuel_gauge.c | 348 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/power/max77705_fuelgauge.h   |  65 +++++++++++++++++++++++
 4 files changed, 421 insertions(+)

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index fe84d2004f57..7c16403c263d 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -579,6 +579,13 @@ config CHARGER_MAX77705
 	help
 	  Say Y to enable support for the Maxim MAX77705 battery charger.
 
+config FUEL_GAUGE_MAX77705
+	tristate "Maxim MAX77705 fuel gauge driver"
+	depends on MFD_MAX77705
+	default n
+	help
+	  Say Y to enable support for MAXIM MAX77705 fuel gauge driver.
+
 config CHARGER_MAX77976
 	tristate "Maxim MAX77976 battery charger driver"
 	depends on I2C
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index daa9228fa04b..b949600a6207 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
 obj-$(CONFIG_CHARGER_MAX77650)	+= max77650-charger.o
 obj-$(CONFIG_CHARGER_MAX77693)	+= max77693_charger.o
 obj-$(CONFIG_CHARGER_MAX77705)	+= max77705_charger.o
+obj-$(CONFIG_FUEL_GAUGE_MAX77705)	+= max77705_fuel_gauge.o
 obj-$(CONFIG_CHARGER_MAX77976)	+= max77976_charger.o
 obj-$(CONFIG_CHARGER_MAX8997)	+= max8997_charger.o
 obj-$(CONFIG_CHARGER_MAX8998)	+= max8998_charger.o
diff --git a/drivers/power/supply/max77705_fuel_gauge.c b/drivers/power/supply/max77705_fuel_gauge.c
new file mode 100644
index 000000000000..bd3dfcf8fdda
--- /dev/null
+++ b/drivers/power/supply/max77705_fuel_gauge.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2024 Dzmitry Sankouski <dsankouski@gmail>
+//
+// Fuel gauge driver for MAXIM 77705 charger/power-supply.
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/max77693-common.h>
+#include <linux/mfd/max77705-private.h>
+#include <linux/power/max77705_fuelgauge.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/regmap.h>
+
+static const char *max77705_fuelgauge_model		= "max77705";
+static const char *max77705_fuelgauge_manufacturer	= "Maxim Integrated";
+
+static enum power_supply_property max77705_fuelgauge_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_VOLTAGE_OCV,
+	POWER_SUPPLY_PROP_VOLTAGE_AVG,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CURRENT_AVG,
+	POWER_SUPPLY_PROP_CHARGE_NOW,
+	POWER_SUPPLY_PROP_CHARGE_FULL,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
+	POWER_SUPPLY_PROP_TIME_TO_FULL_NOW,
+};
+
+static int max77705_fg_read_reg(struct max77705_fuelgauge_data *fuelgauge,
+				unsigned int reg, unsigned int *val)
+{
+	struct regmap *regmap = fuelgauge->regmap;
+	u8 data[2];
+	int ret;
+
+	ret = regmap_noinc_read(regmap, reg, data, sizeof(data));
+	if (ret < 0)
+		return ret;
+
+	*val = (data[1] << 8) + data[0];
+
+	return 0;
+}
+
+static int max77705_fg_read_temp(struct max77705_fuelgauge_data *fuelgauge,
+				 int *val)
+{
+	struct regmap *regmap = fuelgauge->regmap;
+	u8 data[2] = { 0, 0 };
+	int ret, temperature = 0;
+
+	ret = regmap_noinc_read(regmap, TEMPERATURE_REG, data, sizeof(data));
+	if (ret < 0)
+		return ret;
+
+	if (data[1] & BIT(7))
+		temperature = ((~(data[1])) & 0xFF) + 1;
+	else
+		temperature = data[1] & 0x7f;
+
+	temperature *= 10;
+	temperature += data[0] * 10 / 256;
+	*val = temperature;
+
+	return 0;
+}
+
+static int max77705_fg_check_battery_present(struct max77705_fuelgauge_data
+					     *fuelgauge, int *val)
+{
+	struct regmap *regmap = fuelgauge->regmap;
+	u8 status_data[2];
+	int ret;
+
+	ret = regmap_noinc_read(regmap, STATUS_REG, status_data, sizeof(status_data));
+	if (ret < 0)
+		return ret;
+
+	*val = !(status_data[0] & MAX77705_BAT_ABSENT_MASK);
+
+	return 0;
+}
+
+static int max77705_battery_get_status(struct max77705_fuelgauge_data *fuelgauge,
+					int *val)
+{
+	int current_now;
+	int am_i_supplied;
+	int ret;
+	unsigned int soc_rep;
+
+	am_i_supplied = power_supply_am_i_supplied(fuelgauge->psy_fg);
+	if (am_i_supplied) {
+		if (am_i_supplied == -ENODEV) {
+			dev_err(fuelgauge->dev,
+				"power supply not found, fall back to current-based status checking\n");
+		} else {
+			*val = POWER_SUPPLY_STATUS_CHARGING;
+			return 0;
+		}
+	}
+	ret = max77705_fg_read_reg(fuelgauge, SOCREP_REG, &soc_rep);
+	if (ret)
+		return ret;
+
+	if (soc_rep < 100) {
+		ret = max77705_fg_read_reg(fuelgauge, CURRENT_REG, &current_now);
+		if (ret)
+			return ret;
+
+		if (current_now > 0)
+			*val = POWER_SUPPLY_STATUS_CHARGING;
+		else if (current_now < 0)
+			*val = POWER_SUPPLY_STATUS_DISCHARGING;
+		else
+			*val = POWER_SUPPLY_STATUS_NOT_CHARGING;
+	} else {
+		*val = POWER_SUPPLY_STATUS_FULL;
+	}
+
+	return 0;
+}
+
+static void max77705_unit_adjustment(struct max77705_fuelgauge_data *fuelgauge,
+					 enum power_supply_property psp,
+					 union power_supply_propval *val)
+{
+	const unsigned int base_unit_conversion = 1000;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		val->intval = max77705_fg_vs_convert(val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		val->intval = max77705_fg_cs_convert(val->intval,
+						     fuelgauge->rsense_conductance);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		val->intval *= base_unit_conversion;
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		val->intval = min(val->intval, 100);
+		break;
+	default:
+		dev_dbg(fuelgauge->dev,
+			"%s: no need for unit conversion %d\n", __func__, psp);
+	}
+}
+
+static int max77705_fg_get_property(struct power_supply *psy,
+				    enum power_supply_property psp,
+				    union power_supply_propval *val)
+{
+	struct max77705_fuelgauge_data *fuelgauge =
+	    power_supply_get_drvdata(psy);
+	int ret;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		ret = max77705_battery_get_status(fuelgauge, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_PRESENT:
+		ret = max77705_fg_check_battery_present(fuelgauge, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = max77705_fg_read_reg(fuelgauge, VCELL_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		ret = max77705_fg_read_reg(fuelgauge, VFOCV_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		ret = max77705_fg_read_reg(fuelgauge, AVR_VCELL_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = max77705_fg_read_reg(fuelgauge, CURRENT_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = max77705_fg_read_reg(fuelgauge, AVG_CURRENT_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = max77705_fg_read_reg(fuelgauge, REMCAP_REP_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = max77705_fg_read_reg(fuelgauge, FULLCAP_REP_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = max77705_fg_read_reg(fuelgauge, DESIGNCAP_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		ret = max77705_fg_read_reg(fuelgauge, SOCREP_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_TEMP:
+		ret = max77705_fg_read_temp(fuelgauge, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
+		ret = max77705_fg_read_reg(fuelgauge, TIME_TO_EMPTY_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
+		ret = max77705_fg_read_reg(fuelgauge, TIME_TO_FULL_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_CYCLE_COUNT:
+		ret = max77705_fg_read_reg(fuelgauge, CYCLES_REG, &val->intval);
+		break;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = max77705_fuelgauge_model;
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURER:
+		val->strval = max77705_fuelgauge_manufacturer;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	max77705_unit_adjustment(fuelgauge, psp, val);
+
+	return 0;
+}
+
+static const struct power_supply_desc max77705_fg_desc = {
+	.name = "max77705-fuel-gauge",
+	.type = POWER_SUPPLY_TYPE_BATTERY,
+	.properties = max77705_fuelgauge_props,
+	.num_properties = ARRAY_SIZE(max77705_fuelgauge_props),
+	.get_property = max77705_fg_get_property,
+};
+
+static int max77705_fg_set_charge_design(struct regmap *regmap, int value)
+{
+	u8 data[2];
+	int value_mah;
+
+	value_mah = value / 1000;
+	data[0] = value_mah & 0xFF;
+	data[1] = (value_mah >> 8) & 0xFF;
+
+	return regmap_noinc_write(regmap, DESIGNCAP_REG, data, sizeof(data));
+}
+
+static int max77705_battery_settings(struct max77705_fuelgauge_data *fuelgauge)
+{
+	struct power_supply_battery_info *info;
+	struct regmap *regmap = fuelgauge->regmap;
+	int ret;
+
+	ret = power_supply_get_battery_info(fuelgauge->psy_fg, &info);
+	if (ret)
+		return ret;
+
+	fuelgauge->bat_info = info;
+
+	if (info->energy_full_design_uwh != info->charge_full_design_uah) {
+		if (info->charge_full_design_uah == -EINVAL)
+			dev_warn(fuelgauge->dev, "missing battery:charge-full-design-microamp-hours\n");
+		ret = max77705_fg_set_charge_design(regmap, info->charge_full_design_uah);
+	}
+
+	return ret;
+}
+
+static int max77705_fuelgauge_parse_dt(struct max77705_fuelgauge_data
+				       *fuelgauge)
+{
+	struct device *dev = fuelgauge->dev;
+	struct device_node *np = dev->of_node;
+	int ret;
+	unsigned int rsense;
+
+	if (!np) {
+		dev_err(dev, "no fuelgauge OF node\n");
+		return -EINVAL;
+	}
+	ret = of_property_read_u32(np, "shunt-resistor-micro-ohms",
+				   &rsense);
+	if (ret < 0) {
+		dev_warn(dev, "No shunt-resistor-micro-ohms property, assume default\n");
+		fuelgauge->rsense_conductance = 100;
+	} else
+		fuelgauge->rsense_conductance = 1000000 / rsense; /* rsense conductance in Ohm^-1 */
+
+	return 0;
+}
+
+static int max77705_fuelgauge_probe(struct platform_device *pdev)
+{
+	struct max77693_dev *max77705 = dev_get_drvdata(pdev->dev.parent);
+	struct max77705_fuelgauge_data *fuelgauge;
+	struct power_supply_config fuelgauge_cfg = { };
+	struct device *dev = &pdev->dev;
+	int ret = 0;
+
+	fuelgauge = devm_kzalloc(dev, sizeof(*fuelgauge), GFP_KERNEL);
+	if (!fuelgauge)
+		return -ENOMEM;
+
+	fuelgauge->dev = dev;
+	fuelgauge->regmap = max77705->regmap_fg;
+
+	ret = max77705_fuelgauge_parse_dt(fuelgauge);
+	if (ret < 0)
+		return ret;
+
+	fuelgauge_cfg.drv_data = fuelgauge;
+	fuelgauge_cfg.of_node = fuelgauge->dev->of_node;
+
+	fuelgauge->psy_fg = devm_power_supply_register(&pdev->dev,
+							&max77705_fg_desc,
+							&fuelgauge_cfg);
+
+	if (IS_ERR(fuelgauge->psy_fg))
+		return PTR_ERR(fuelgauge->psy_fg);
+
+	return max77705_battery_settings(fuelgauge);
+}
+
+static const struct of_device_id max77705_fg_of_match[] = {
+	{ .compatible = "maxim,max77705-fuel-gauge" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77705_fg_of_match);
+
+static struct platform_driver max77705_fuelgauge_driver = {
+	.driver = {
+		.name = "max77705-fuel-gauge",
+		.of_match_table = max77705_fg_of_match,
+	},
+	.probe = max77705_fuelgauge_probe,
+};
+module_platform_driver(max77705_fuelgauge_driver);
+
+MODULE_DESCRIPTION("Maxim MAX77705 Fuel Gauge Driver");
+MODULE_AUTHOR("Dzmitry Sankouski <dsankouski@gmail>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/power/max77705_fuelgauge.h b/include/linux/power/max77705_fuelgauge.h
new file mode 100644
index 000000000000..dfd91f097817
--- /dev/null
+++ b/include/linux/power/max77705_fuelgauge.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+//
+// Copyright (C) 2024 Dzmitry Sankouski <dsankouski@gmail.org>
+//
+// Fuel gauge driver header for MAXIM 77705 charger/power-supply.
+
+#ifndef __MAX77705_FUELGAUGE_H
+#define __MAX77705_FUELGAUGE_H __FILE__
+
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+
+#define ALERT_EN			4
+#define CAPACITY_SCALE_DEFAULT_CURRENT	1000
+#define CAPACITY_SCALE_HV_CURRENT	600
+// Current and capacity values are displayed as a voltage
+// and must be divided by the sense resistor to determine Amps or Amp-hours.
+// This should be applied to all current, charge, energy registers,
+// except ModelGauge m5 Algorithm related ones.
+// current sense resolution
+#define MAX77705_FG_CS_ADC_RESOLUTION	15625 // 1.5625 microvolts
+// voltage sense resolution
+#define MAX77705_FG_VS_ADC_RESOLUTION	78125 // 78.125 microvolts
+// CONFIG_REG register
+#define MAX77705_SOC_ALERT_EN_MASK	BIT(2)
+// When set to 1, external temperature measurements should be written from the host
+#define MAX77705_TEX_MASK		BIT(8)
+// Enable Thermistor
+#define MAX77705_ETHRM_MASK		BIT(5)
+// CONFIG2_REG register
+#define MAX77705_AUTO_DISCHARGE_EN_MASK BIT(9)
+// STATUS_REG register
+#define MAX77705_BAT_ABSENT_MASK	BIT(3)
+
+// @brief Convert voltage register value to micro volts
+// @param reg_val - register value
+// @return voltage in micro Volts
+inline u64 max77705_fg_vs_convert(u16 reg_val)
+{
+	u64 result = (u64)reg_val * MAX77705_FG_VS_ADC_RESOLUTION;
+
+	return result / 1000;
+}
+
+// @brief Convert current register value to micro volts
+// @param reg_val - register value
+// @param rsense_conductance - current sense resistor conductance in Ohm^-1
+// @return voltage in micro Volts
+inline s32 max77705_fg_cs_convert(s16 reg_val, u32 rsense_conductance)
+{
+	s64 result = (s64)reg_val * rsense_conductance * MAX77705_FG_CS_ADC_RESOLUTION;
+
+	return result / 10000;
+}
+
+struct max77705_fuelgauge_data {
+	struct device *dev;
+	struct regmap *regmap;
+	struct power_supply *psy_fg;
+	struct power_supply_battery_info *bat_info;
+	u32 rsense_conductance;
+};
+
+#endif // __MAX77705_FUELGAUGE_H

-- 
2.39.2

Hi Dzmitry,

kernel test robot noticed the following build errors:

[auto build test ERROR on 58ca61c1a866bfdaa5e19fb19a2416764f847d75]

url:    https://github.com/intel-lab-lkp/linux/commits/Dzmitry-Sankouski/power-supply-add-undervoltage-health-status-property/20241008-000014
base:   58ca61c1a866bfdaa5e19fb19a2416764f847d75
patch link:    https://lore.kernel.org/r/20241007-starqltechn_integration_upstream-v6-6-0d38b5090c57%40gmail.com
patch subject: [PATCH v6 6/7] power: supply: max77705: Add fuel gauge driver for Maxim 77705
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20241012/202410120358.OZgWQ1aJ-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241012/202410120358.OZgWQ1aJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410120358.OZgWQ1aJ-lkp@intel.com/

All errors (new ones prefixed by >>, old ones prefixed by <<):

WARNING: modpost: missing MODULE_DESCRIPTION() in security/tomoyo/tomoyo.o
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/bridge/imx/imx-legacy-bridge.o
>> ERROR: modpost: "__udivdi3" [drivers/power/supply/max77705_fuel_gauge.ko] undefined!
>> ERROR: modpost: "__divdi3" [drivers/power/supply/max77705_fuel_gauge.ko] undefined!

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for MODVERSIONS
   Depends on [n]: MODULES [=y] && !COMPILE_TEST [=y]
   Selected by [y]:
   - RANDSTRUCT_FULL [=y] && (CC_HAS_RANDSTRUCT [=n] || GCC_PLUGINS [=y]) && MODULES [=y]
   WARNING: unmet direct dependencies detected for GET_FREE_REGION
   Depends on [n]: SPARSEMEM [=n]
   Selected by [m]:
   - RESOURCE_KUNIT_TEST [=m] && RUNTIME_TESTING_MENU [=y] && KUNIT [=m]

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Hi Dzmitry,

kernel test robot noticed the following build errors:

[auto build test ERROR on 58ca61c1a866bfdaa5e19fb19a2416764f847d75]

url:    https://github.com/intel-lab-lkp/linux/commits/Dzmitry-Sankouski/power-supply-add-undervoltage-health-status-property/20241008-000014
base:   58ca61c1a866bfdaa5e19fb19a2416764f847d75
patch link:    https://lore.kernel.org/r/20241007-starqltechn_integration_upstream-v6-6-0d38b5090c57%40gmail.com
patch subject: [PATCH v6 6/7] power: supply: max77705: Add fuel gauge driver for Maxim 77705
config: i386-allyesconfig (https://download.01.org/0day-ci/archive/20241011/202410111913.5ADtNHNM-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241011/202410111913.5ADtNHNM-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410111913.5ADtNHNM-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: drivers/power/supply/max77705_fuel_gauge.o: in function `max77705_fg_get_property':
>> max77705_fuel_gauge.c:(.text+0x244): undefined reference to `__divdi3'
>> ld: max77705_fuel_gauge.c:(.text+0x2b1): undefined reference to `__udivdi3'
   ld: drivers/power/supply/max77705_fuel_gauge.o: in function `max77705_fg_vs_convert':
>> max77705_fuel_gauge.c:(.text+0x6c2): undefined reference to `__udivdi3'
   ld: drivers/power/supply/max77705_fuel_gauge.o: in function `max77705_fg_cs_convert':
   max77705_fuel_gauge.c:(.text+0x706): undefined reference to `__divdi3'

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for MODVERSIONS
   Depends on [n]: MODULES [=y] && !COMPILE_TEST [=y]
   Selected by [y]:
   - RANDSTRUCT_FULL [=y] && (CC_HAS_RANDSTRUCT [=n] || GCC_PLUGINS [=y]) && MODULES [=y]
   WARNING: unmet direct dependencies detected for GET_FREE_REGION
   Depends on [n]: SPARSEMEM [=n]
   Selected by [y]:
   - RESOURCE_KUNIT_TEST [=y] && RUNTIME_TESTING_MENU [=y] && KUNIT [=y]

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0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Hi Dzmitry,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 58ca61c1a866bfdaa5e19fb19a2416764f847d75]

url:    https://github.com/intel-lab-lkp/linux/commits/Dzmitry-Sankouski/power-supply-add-undervoltage-health-status-property/20241008-000014
base:   58ca61c1a866bfdaa5e19fb19a2416764f847d75
patch link:    https://lore.kernel.org/r/20241007-starqltechn_integration_upstream-v6-6-0d38b5090c57%40gmail.com
patch subject: [PATCH v6 6/7] power: supply: max77705: Add fuel gauge driver for Maxim 77705
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20241011/202410110404.etzjIhE5-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241011/202410110404.etzjIhE5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410110404.etzjIhE5-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/power/supply/max77705_fuel_gauge.c:220:7: warning: variable 'ret' is used uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
     220 |         case POWER_SUPPLY_PROP_MANUFACTURER:
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/power/supply/max77705_fuel_gauge.c:227:6: note: uninitialized use occurs here
     227 |         if (ret)
         |             ^~~
   drivers/power/supply/max77705_fuel_gauge.c:217:7: warning: variable 'ret' is used uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
     217 |         case POWER_SUPPLY_PROP_MODEL_NAME:
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/power/supply/max77705_fuel_gauge.c:227:6: note: uninitialized use occurs here
     227 |         if (ret)
         |             ^~~
   drivers/power/supply/max77705_fuel_gauge.c:169:9: note: initialize the variable 'ret' to silence this warning
     169 |         int ret;
         |                ^
         |                 = 0
   2 warnings generated.

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for MODVERSIONS
   Depends on [n]: MODULES [=y] && !COMPILE_TEST [=y]
   Selected by [y]:
   - RANDSTRUCT_FULL [=y] && (CC_HAS_RANDSTRUCT [=y] || GCC_PLUGINS [=n]) && MODULES [=y]


vim +/ret +220 drivers/power/supply/max77705_fuel_gauge.c

   162	
   163	static int max77705_fg_get_property(struct power_supply *psy,
   164					    enum power_supply_property psp,
   165					    union power_supply_propval *val)
   166	{
   167		struct max77705_fuelgauge_data *fuelgauge =
   168		    power_supply_get_drvdata(psy);
   169		int ret;
   170	
   171		switch (psp) {
   172		case POWER_SUPPLY_PROP_STATUS:
   173			ret = max77705_battery_get_status(fuelgauge, &val->intval);
   174			break;
   175		case POWER_SUPPLY_PROP_PRESENT:
   176			ret = max77705_fg_check_battery_present(fuelgauge, &val->intval);
   177			break;
   178		case POWER_SUPPLY_PROP_VOLTAGE_NOW:
   179			ret = max77705_fg_read_reg(fuelgauge, VCELL_REG, &val->intval);
   180			break;
   181		case POWER_SUPPLY_PROP_VOLTAGE_OCV:
   182			ret = max77705_fg_read_reg(fuelgauge, VFOCV_REG, &val->intval);
   183			break;
   184		case POWER_SUPPLY_PROP_VOLTAGE_AVG:
   185			ret = max77705_fg_read_reg(fuelgauge, AVR_VCELL_REG, &val->intval);
   186			break;
   187		case POWER_SUPPLY_PROP_CURRENT_NOW:
   188			ret = max77705_fg_read_reg(fuelgauge, CURRENT_REG, &val->intval);
   189			break;
   190		case POWER_SUPPLY_PROP_CURRENT_AVG:
   191			ret = max77705_fg_read_reg(fuelgauge, AVG_CURRENT_REG, &val->intval);
   192			break;
   193		case POWER_SUPPLY_PROP_CHARGE_NOW:
   194			ret = max77705_fg_read_reg(fuelgauge, REMCAP_REP_REG, &val->intval);
   195			break;
   196		case POWER_SUPPLY_PROP_CHARGE_FULL:
   197			ret = max77705_fg_read_reg(fuelgauge, FULLCAP_REP_REG, &val->intval);
   198			break;
   199		case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
   200			ret = max77705_fg_read_reg(fuelgauge, DESIGNCAP_REG, &val->intval);
   201			break;
   202		case POWER_SUPPLY_PROP_CAPACITY:
   203			ret = max77705_fg_read_reg(fuelgauge, SOCREP_REG, &val->intval);
   204			break;
   205		case POWER_SUPPLY_PROP_TEMP:
   206			ret = max77705_fg_read_temp(fuelgauge, &val->intval);
   207			break;
   208		case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
   209			ret = max77705_fg_read_reg(fuelgauge, TIME_TO_EMPTY_REG, &val->intval);
   210			break;
   211		case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
   212			ret = max77705_fg_read_reg(fuelgauge, TIME_TO_FULL_REG, &val->intval);
   213			break;
   214		case POWER_SUPPLY_PROP_CYCLE_COUNT:
   215			ret = max77705_fg_read_reg(fuelgauge, CYCLES_REG, &val->intval);
   216			break;
   217		case POWER_SUPPLY_PROP_MODEL_NAME:
   218			val->strval = max77705_fuelgauge_model;
   219			break;
 > 220		case POWER_SUPPLY_PROP_MANUFACTURER:
   221			val->strval = max77705_fuelgauge_manufacturer;
   222			break;
   223		default:
   224			return -EINVAL;
   225		}
   226	
   227		if (ret)
   228			return ret;
   229	
   230		max77705_unit_adjustment(fuelgauge, psp, val);
   231	
   232		return 0;
   233	}
   234	

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0-DAY CI Kernel Test Service
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