static int elants_i2c_probe()

in touchscreen/elants_i2c.c [1416:1585]

• 128 lines of code
• 26 McCabe index (conditional complexity)

static int elants_i2c_probe(struct i2c_client *client)
{
	union i2c_smbus_data dummy;
	struct elants_data *ts;
	unsigned long irqflags;
	int error;

	/* Don't bind to i2c-hid compatible devices, these are handled by the i2c-hid drv. */
	if (elants_acpi_is_hid_device(&client->dev)) {
		dev_warn(&client->dev, "This device appears to be an I2C-HID device, not binding\n");
		return -ENODEV;
	}

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		dev_err(&client->dev, "I2C check functionality error\n");
		return -ENXIO;
	}

	ts = devm_kzalloc(&client->dev, sizeof(struct elants_data), GFP_KERNEL);
	if (!ts)
		return -ENOMEM;

	mutex_init(&ts->sysfs_mutex);
	init_completion(&ts->cmd_done);

	ts->client = client;
	ts->chip_id = (enum elants_chip_id)(uintptr_t)device_get_match_data(&client->dev);
	i2c_set_clientdata(client, ts);

	ts->vcc33 = devm_regulator_get(&client->dev, "vcc33");
	if (IS_ERR(ts->vcc33)) {
		error = PTR_ERR(ts->vcc33);
		if (error != -EPROBE_DEFER)
			dev_err(&client->dev,
				"Failed to get 'vcc33' regulator: %d\n",
				error);
		return error;
	}

	ts->vccio = devm_regulator_get(&client->dev, "vccio");
	if (IS_ERR(ts->vccio)) {
		error = PTR_ERR(ts->vccio);
		if (error != -EPROBE_DEFER)
			dev_err(&client->dev,
				"Failed to get 'vccio' regulator: %d\n",
				error);
		return error;
	}

	ts->reset_gpio = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_LOW);
	if (IS_ERR(ts->reset_gpio)) {
		error = PTR_ERR(ts->reset_gpio);

		if (error == -EPROBE_DEFER)
			return error;

		if (error != -ENOENT && error != -ENOSYS) {
			dev_err(&client->dev,
				"failed to get reset gpio: %d\n",
				error);
			return error;
		}

		ts->keep_power_in_suspend = true;
	}

	error = elants_i2c_power_on(ts);
	if (error)
		return error;

	error = devm_add_action_or_reset(&client->dev,
					 elants_i2c_power_off, ts);
	if (error) {
		dev_err(&client->dev,
			"failed to install power off action: %d\n", error);
		return error;
	}

	/* Make sure there is something at this address */
	if (i2c_smbus_xfer(client->adapter, client->addr, 0,
			   I2C_SMBUS_READ, 0, I2C_SMBUS_BYTE, &dummy) < 0) {
		dev_err(&client->dev, "nothing at this address\n");
		return -ENXIO;
	}

	error = elants_i2c_initialize(ts);
	if (error) {
		dev_err(&client->dev, "failed to initialize: %d\n", error);
		return error;
	}

	ts->input = devm_input_allocate_device(&client->dev);
	if (!ts->input) {
		dev_err(&client->dev, "Failed to allocate input device\n");
		return -ENOMEM;
	}

	ts->input->name = "Elan Touchscreen";
	ts->input->id.bustype = BUS_I2C;

	/* Multitouch input params setup */

	input_set_abs_params(ts->input, ABS_MT_POSITION_X, 0, ts->x_max, 0, 0);
	input_set_abs_params(ts->input, ABS_MT_POSITION_Y, 0, ts->y_max, 0, 0);
	input_set_abs_params(ts->input, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
	input_set_abs_params(ts->input, ABS_MT_PRESSURE, 0, 255, 0, 0);
	input_set_abs_params(ts->input, ABS_MT_TOOL_TYPE,
			     0, MT_TOOL_PALM, 0, 0);

	touchscreen_parse_properties(ts->input, true, &ts->prop);

	if (ts->chip_id == EKTF3624 && ts->phy_x && ts->phy_y) {
		/* calculate resolution from size */
		ts->x_res = DIV_ROUND_CLOSEST(ts->prop.max_x, ts->phy_x);
		ts->y_res = DIV_ROUND_CLOSEST(ts->prop.max_y, ts->phy_y);
	}

	input_abs_set_res(ts->input, ABS_MT_POSITION_X, ts->x_res);
	input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
	input_abs_set_res(ts->input, ABS_MT_TOUCH_MAJOR, ts->major_res);

	error = input_mt_init_slots(ts->input, MAX_CONTACT_NUM,
				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
	if (error) {
		dev_err(&client->dev,
			"failed to initialize MT slots: %d\n", error);
		return error;
	}

	error = input_register_device(ts->input);
	if (error) {
		dev_err(&client->dev,
			"unable to register input device: %d\n", error);
		return error;
	}

	/*
	 * Platform code (ACPI, DTS) should normally set up interrupt
	 * for us, but in case it did not let's fall back to using falling
	 * edge to be compatible with older Chromebooks.
	 */
	irqflags = irq_get_trigger_type(client->irq);
	if (!irqflags)
		irqflags = IRQF_TRIGGER_FALLING;

	error = devm_request_threaded_irq(&client->dev, client->irq,
					  NULL, elants_i2c_irq,
					  irqflags | IRQF_ONESHOT,
					  client->name, ts);
	if (error) {
		dev_err(&client->dev, "Failed to register interrupt\n");
		return error;
	}

	/*
	 * Systems using device tree should set up wakeup via DTS,
	 * the rest will configure device as wakeup source by default.
	 */
	if (!client->dev.of_node)
		device_init_wakeup(&client->dev, true);

	error = devm_device_add_group(&client->dev, &elants_attribute_group);
	if (error) {
		dev_err(&client->dev, "failed to create sysfs attributes: %d\n",
			error);
		return error;
	}

	return 0;
}