[PATCH v3 1/2] power: supply: Add STC3117 fuel gauge unit driver

[Bhavin Sharma]

Adding minimal support for stc3117 fuel gauge driver
to read battery voltage level

Signed-off-by: Bhavin Sharma <bhavin.sharma@xxxxxxxxxxxxxxxxx>
---
Changelogs :

v2 -> v3
- Resolved kernel test robot build warnings
- Aligned included header files in alphabetical order
- Removed unused header files
- Removed unnecessary blank lines
- Aligned all the macros in alphabetical order
- Changed macro LSB_VALUE to VOLTAGE_LSB_VALUE
- Dropped function prototypes and arranged the code accordingly
- Used macros instead of static numbers for array declaration
- Removed redundant code
- Replaced 'power_supply_register' with 'devm_power_supply_register' and 'pr_err' with 'dev_err'
- Removed global variables

v1 -> v2
- No change
---
 drivers/power/supply/Kconfig              |   7 ++
 drivers/power/supply/Makefile             |   1 +
 drivers/power/supply/stc3117_fuel_gauge.c | 107 ++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 drivers/power/supply/stc3117_fuel_gauge.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index f21cb05815ec..e2e3af4bcd5f 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -875,6 +875,13 @@ config FUEL_GAUGE_SC27XX
 	  Say Y here to enable support for fuel gauge with SC27XX
 	  PMIC chips.
 
+config FUEL_GAUGE_STC3117
+        tristate "STMicroelectronics STC3117 fuel gauge driver"
+        depends on I2C
+        help
+          Say Y here to enable support for fuel gauge with STC3117
+          PMIC chips.
+
 config CHARGER_UCS1002
 	tristate "Microchip UCS1002 USB Port Power Controller"
 	depends on I2C
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 58b567278034..be8961661bd1 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -104,6 +104,7 @@ obj-$(CONFIG_CHARGER_CROS_USBPD)	+= cros_usbpd-charger.o
 obj-$(CONFIG_CHARGER_CROS_PCHG)	+= cros_peripheral_charger.o
 obj-$(CONFIG_CHARGER_SC2731)	+= sc2731_charger.o
 obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o
+obj-$(CONFIG_FUEL_GAUGE_STC3117)        += stc3117_fuel_gauge.o
 obj-$(CONFIG_CHARGER_UCS1002)	+= ucs1002_power.o
 obj-$(CONFIG_CHARGER_BD99954)	+= bd99954-charger.o
 obj-$(CONFIG_CHARGER_WILCO)	+= wilco-charger.o
diff --git a/drivers/power/supply/stc3117_fuel_gauge.c b/drivers/power/supply/stc3117_fuel_gauge.c
new file mode 100644
index 000000000000..29eb00b44e21
--- /dev/null
+++ b/drivers/power/supply/stc3117_fuel_gauge.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * stc3117_fuel_gauge.c - STMicroelectronics STC3117 Fuel Gauge Driver
+ *
+ * Copyright (c) 2024 Silicon Signals Pvt Ltd.
+ * Author:      Bhavin Sharma <bhavin.sharma@xxxxxxxxxxxxxxxxx>
+ *              Hardevsinh Palaniya <hardevsinh.palaniya@xxxxxxxxxxxxxxxxxx>
+ */
+
+#include <linux/i2c.h>
+#include <linux/power_supply.h>
+
+#define VOLTAGE_DATA_SIZE	2		// in bytes
+#define VOLTAGE_LSB_VALUE	2200		// in micro-volts
+#define VOLTAGE_REG_ADDR	0x08
+#define VOLTAGE_REG_ADDR_SIZE	1		// in bytes
+
+static int stc3117_get_batt_volt(const struct i2c_client *stc_client)
+{
+	int ret, volt = 0;
+	char i2c_tx = VOLTAGE_REG_ADDR, i2c_rx[VOLTAGE_DATA_SIZE] = {0};
+
+	ret = i2c_master_send(stc_client, &i2c_tx, VOLTAGE_REG_ADDR_SIZE);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_master_recv(stc_client, i2c_rx, VOLTAGE_DATA_SIZE);
+	if (ret < 0)
+		return ret;
+
+	volt = (i2c_rx[1] << 8) + i2c_rx[0];
+	volt *= VOLTAGE_LSB_VALUE;
+
+	return volt;
+}
+
+static int stc3117_get_property(struct power_supply *psy,
+	enum power_supply_property psp, union power_supply_propval *val)
+{
+	struct i2c_client *client = to_i2c_client(psy->dev.parent);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		val->intval = stc3117_get_batt_volt(client);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static enum power_supply_property stc3117_battery_props[] = {
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+};
+
+static const struct power_supply_desc stc3117_battery_desc = {
+	.name = "stc3117-battery",
+	.type = POWER_SUPPLY_TYPE_BATTERY,
+	.get_property = stc3117_get_property,
+	.properties = stc3117_battery_props,
+	.num_properties = ARRAY_SIZE(stc3117_battery_props),
+};
+
+static int stc3117_probe(struct i2c_client *client)
+{
+	struct power_supply_config psy_cfg = {};
+	struct device *dev;
+	struct power_supply *stc_sply;
+
+	dev = &client->dev;
+
+	psy_cfg.of_node = dev->of_node;
+
+	stc_sply = devm_power_supply_register(dev, &stc3117_battery_desc, &psy_cfg);
+	if (IS_ERR(stc_sply))
+		dev_err(dev, "failed to register battery\n");
+
+	return 0;
+}
+
+static const struct i2c_device_id stc3117_id[] = {
+	{"stc3117", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, stc3117_id);
+
+static const struct of_device_id stc3117_of_match[] = {
+	{ .compatible = "st,stc3117" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stc3117_of_match);
+
+static struct i2c_driver stc3117_i2c_driver = {
+	.driver = {
+		.name = "stc3117_i2c_driver",
+		.of_match_table = stc3117_of_match,
+	},
+	.probe = stc3117_probe,
+	.id_table = stc3117_id,
+};
+
+module_i2c_driver(stc3117_i2c_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bhavin Sharma <bhavin.sharma@xxxxxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Hardevsinh Palaniya <hardevsinh.palaniya@xxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("STC3117 Fuel Gauge Driver");
-- 
2.25.1