static int ltc294x_i2c_probe()

in supply/ltc2941-battery-gauge.c [449:563]

• 98 lines of code
• 18 McCabe index (conditional complexity)

static int ltc294x_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
{
	struct power_supply_config psy_cfg = {};
	struct ltc294x_info *info;
	struct device_node *np;
	int ret;
	u32 prescaler_exp;
	s32 r_sense;
	u8 status;

	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
	if (info == NULL)
		return -ENOMEM;

	i2c_set_clientdata(client, info);

	np = of_node_get(client->dev.of_node);

	info->id = (enum ltc294x_id) (uintptr_t) of_device_get_match_data(
							&client->dev);
	info->supply_desc.name = np->name;

	/* r_sense can be negative, when sense+ is connected to the battery
	 * instead of the sense-. This results in reversed measurements. */
	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
	if (ret < 0) {
		dev_err(&client->dev,
			"Could not find lltc,resistor-sense in devicetree\n");
		return ret;
	}
	info->r_sense = r_sense;

	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
		&prescaler_exp);
	if (ret < 0) {
		dev_warn(&client->dev,
			"lltc,prescaler-exponent not in devicetree\n");
		prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
	}

	if (info->id == LTC2943_ID) {
		if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
			prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
		info->Qlsb = ((340 * 50000) / r_sense) /
				(4096 / (1 << (2*prescaler_exp)));
	} else {
		if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
			prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
		info->Qlsb = ((85 * 50000) / r_sense) /
				(128 / (1 << prescaler_exp));
	}

	/* Read status register to check for LTC2942 */
	if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
		ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
		if (ret < 0) {
			dev_err(&client->dev,
				"Could not read status register\n");
			return ret;
		}
		if (status & LTC2941_REG_STATUS_CHIP_ID)
			info->id = LTC2941_ID;
		else
			info->id = LTC2942_ID;
	}

	info->client = client;
	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
	info->supply_desc.properties = ltc294x_properties;
	switch (info->id) {
	case LTC2944_ID:
	case LTC2943_ID:
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties);
		break;
	case LTC2942_ID:
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties) - 1;
		break;
	case LTC2941_ID:
	default:
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties) - 3;
		break;
	}
	info->supply_desc.get_property = ltc294x_get_property;
	info->supply_desc.set_property = ltc294x_set_property;
	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
	info->supply_desc.external_power_changed	= NULL;

	psy_cfg.drv_data = info;

	ret = devm_delayed_work_autocancel(&client->dev, &info->work,
					   ltc294x_work);
	if (ret)
		return ret;

	ret = ltc294x_reset(info, prescaler_exp);
	if (ret < 0) {
		dev_err(&client->dev, "Communication with chip failed\n");
		return ret;
	}

	info->supply = devm_power_supply_register(&client->dev,
						  &info->supply_desc, &psy_cfg);
	if (IS_ERR(info->supply)) {
		dev_err(&client->dev, "failed to register ltc2941\n");
		return PTR_ERR(info->supply);
	} else {
		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	}

	return 0;
}