Hi,

On Fri, Jan 23, 2015 at 02:02:45PM +0900, Jaewon Kim wrote:

add -> adds

+	  It is fuel-gauge systems for lithuum-ion (Li+) batteries in handled and
+	  portable devices. The MAX17040 is configured to operate with a single
+	  lithium cell.

It is a fuel-gauge for a lithium-ion batteries with a single
cell and can be found in portable devices.

so

val = reg_data[1]?

+	return val;
+}
+
+static int max77843_battery_get_energy_prop(struct max77843_battery *battery,
+		enum power_supply_property psp)
+{
+	struct regmap *regmap = battery->regmap;
+	unsigned int reg;
+	int ret, val;
+	u8 reg_data[2];
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_ENERGY_FULL:
+		reg = MAX77843_FG_REG_FULLCAP;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_NOW:
+		reg = MAX77843_FG_REG_REMCAP_REP;
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_AVG:
+		reg = MAX77843_FG_REG_REMCAP_AV;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_bulk_read(regmap, reg, reg_data, 2);
+	if (ret) {
+		dev_err(battery->dev, "Failed to read fuelgauge register\n");
+		return ret;
+	}
+
+	val = (reg_data[1] << 8) | reg_data[0];
+
+	return val;
+}
+
+static int max77843_battery_get_current_prop(struct max77843_battery *battery,
+		enum power_supply_property psp)
+{
+	struct regmap *regmap = battery->regmap;
+	unsigned int reg;
+	int ret, val;
+	u8 reg_data[2];
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		reg = MAX77843_FG_REG_CURRENT;
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		reg = MAX77843_FG_REG_AVG_CURRENT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_bulk_read(regmap, reg, reg_data, 2);
+	if (ret) {
+		dev_err(battery->dev, "Failed to read fuelgauge register\n");
+		return ret;
+	}
+
+	val = (reg_data[1] << 8) | reg_data[0];
+	if (val & 0x8000) {
+		/* Negative */
+		val = ~val & 0xffff;
+		val++;
+		val *= -1;
+	}
+	/* Unit of current is mA */
+	val =  val * 15625 / 100000;
+
+	return val;
+}
+
+static int max77843_battery_get_voltage_prop(struct max77843_battery *battery,
+		enum power_supply_property psp)
+{
+	struct regmap *regmap = battery->regmap;
+	unsigned int reg;
+	int ret, val;
+	u8 reg_data[2];
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		reg = MAX77843_FG_REG_VCELL;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		reg = MAX77843_FG_REG_AVG_VCELL;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		reg = MAX77843_FG_REG_OCV;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_bulk_read(regmap, reg, reg_data, 2);
+	if (ret) {
+		dev_err(battery->dev, "Failed to read fuelgauge register\n");
+		return ret;
+	}
+
+	val = ((reg_data[1] << 4) + (reg_data[0] >> 4)) * 125;
+	val /= 100;
+
+	return val;
+}
+
+static const char *model_name = "MAX77843";
+static const char *manufacturer = "Maxim Integrated";
+
+static int max77843_battery_get_property(struct power_supply *psy,
+		enum power_supply_property psp,
+		union power_supply_propval *val)
+{
+	struct max77843_battery *battery = container_of(psy,
+				struct max77843_battery, psy);
+	switch (psp) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		val->intval = max77843_battery_get_voltage_prop(battery, psp);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		val->intval = max77843_battery_get_current_prop(battery, psp);
+		break;
+	case POWER_SUPPLY_PROP_ENERGY_FULL:
+	case POWER_SUPPLY_PROP_ENERGY_NOW:
+	case POWER_SUPPLY_PROP_ENERGY_AVG:
+		val->intval = max77843_battery_get_energy_prop(battery, psp);
+		break;
+	case POWER_SUPPLY_PROP_CAPACITY:
+		val->intval = max77843_battery_get_capacity(battery);
+		break;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval =  model_name;
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURER:
+		val->strval = manufacturer;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static enum power_supply_property max77843_battery_props[] = {
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_VOLTAGE_AVG,
+	POWER_SUPPLY_PROP_VOLTAGE_OCV,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CURRENT_AVG,
+	POWER_SUPPLY_PROP_ENERGY_FULL,
+	POWER_SUPPLY_PROP_ENERGY_NOW,
+	POWER_SUPPLY_PROP_ENERGY_AVG,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+};
+
+static const struct regmap_config max77843_fuel_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_FG_END,
+};

You always read 2 bytes, so it seems the device uses 16 bit sized
values?

+static int max77843_battery_probe(struct platform_device *pdev)
+{
+	struct max77843 *max77843 = dev_get_drvdata(pdev->dev.parent);
+	struct max77843_battery *battery;
+	int ret;
+
+	battery = devm_kzalloc(&pdev->dev, sizeof(*battery), GFP_KERNEL);
+	if (!battery)
+		return -ENOMEM;
+
+	battery->dev = &pdev->dev;
+	battery->max77843 = max77843;
+
+	battery->client = i2c_new_dummy(max77843->i2c->adapter, I2C_ADDR_FG);
+	if (!battery->client) {
+		dev_err(&pdev->dev, "Failed to get dummy i2c client.\n");
+		return PTR_ERR(battery->client);
+	}
+	i2c_set_clientdata(battery->client, max77843);
+
+	battery->regmap = devm_regmap_init_i2c(battery->client,
+			&max77843_fuel_regmap_config);
+	if (IS_ERR(battery->regmap)) {
+		ret = PTR_ERR(battery->regmap);
+		goto err_i2c;
+	}
+
+	platform_set_drvdata(pdev, battery);
+
+	battery->psy.name	= "max77843-fuelgauge";
+	battery->psy.type	= POWER_SUPPLY_TYPE_BATTERY;
+	battery->psy.get_property	= max77843_battery_get_property;
+	battery->psy.properties		= max77843_battery_props;
+	battery->psy.num_properties	= ARRAY_SIZE(max77843_battery_props);
+
+	ret = power_supply_register(&pdev->dev, &battery->psy);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed  to register power supply\n");
+		goto err_i2c;
+	}
+
+	return 0;
+
+err_i2c:
+	i2c_unregister_device(battery->client);

This is missing in max77843_battery_remove()

+
+	return ret;
+}
+
+static int max77843_battery_remove(struct platform_device *pdev)
+{
+	struct max77843_battery *battery = platform_get_drvdata(pdev);
+
+	power_supply_unregister(&battery->psy);
+
+	return 0;
+}

[...]

-- Sebastian