static int w1_gpio_probe()

in masters/w1-gpio.c [69:152]

• 57 lines of code
• 12 McCabe index (conditional complexity)

static int w1_gpio_probe(struct platform_device *pdev)
{
	struct w1_bus_master *master;
	struct w1_gpio_platform_data *pdata;
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	/* Enforce open drain mode by default */
	enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN;
	int err;

	if (of_have_populated_dt()) {
		pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
		if (!pdata)
			return -ENOMEM;

		/*
		 * This parameter means that something else than the gpiolib has
		 * already set the line into open drain mode, so we should just
		 * driver it high/low like we are in full control of the line and
		 * open drain will happen transparently.
		 */
		if (of_get_property(np, "linux,open-drain", NULL))
			gflags = GPIOD_OUT_LOW;

		pdev->dev.platform_data = pdata;
	}
	pdata = dev_get_platdata(dev);

	if (!pdata) {
		dev_err(dev, "No configuration data\n");
		return -ENXIO;
	}

	master = devm_kzalloc(dev, sizeof(struct w1_bus_master),
			GFP_KERNEL);
	if (!master) {
		dev_err(dev, "Out of memory\n");
		return -ENOMEM;
	}

	pdata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);
	if (IS_ERR(pdata->gpiod)) {
		dev_err(dev, "gpio_request (pin) failed\n");
		return PTR_ERR(pdata->gpiod);
	}

	pdata->pullup_gpiod =
		devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);
	if (IS_ERR(pdata->pullup_gpiod)) {
		dev_err(dev, "gpio_request_one "
			"(ext_pullup_enable_pin) failed\n");
		return PTR_ERR(pdata->pullup_gpiod);
	}

	master->data = pdata;
	master->read_bit = w1_gpio_read_bit;
	gpiod_direction_output(pdata->gpiod, 1);
	master->write_bit = w1_gpio_write_bit;

	/*
	 * If we are using open drain emulation from the GPIO library,
	 * we need to use this pullup function that hammers the line
	 * high using a raw accessor to provide pull-up for the w1
	 * line.
	 */
	if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)
		master->set_pullup = w1_gpio_set_pullup;

	err = w1_add_master_device(master);
	if (err) {
		dev_err(dev, "w1_add_master device failed\n");
		return err;
	}

	if (pdata->enable_external_pullup)
		pdata->enable_external_pullup(1);

	if (pdata->pullup_gpiod)
		gpiod_set_value(pdata->pullup_gpiod, 1);

	platform_set_drvdata(pdev, master);

	return 0;
}