int gpiod_export()

in gpiolib-sysfs.c [567:649]
69 lines of code
14 McCabe index (conditional complexity)

int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
	struct gpio_chip	*chip;
	struct gpio_device	*gdev;
	struct gpiod_data	*data;
	unsigned long		flags;
	int			status;
	const char		*ioname = NULL;
	struct device		*dev;
	int			offset;

	/* can't export until sysfs is available ... */
	if (!gpio_class.p) {
		pr_debug("%s: called too early!\n", __func__);
		return -ENOENT;
	}

	if (!desc) {
		pr_debug("%s: invalid gpio descriptor\n", __func__);
		return -EINVAL;
	}

	gdev = desc->gdev;
	chip = gdev->chip;

	mutex_lock(&sysfs_lock);

	/* check if chip is being removed */
	if (!chip || !gdev->mockdev) {
		status = -ENODEV;
		goto err_unlock;
	}

	spin_lock_irqsave(&gpio_lock, flags);
	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
	     test_bit(FLAG_EXPORT, &desc->flags)) {
		spin_unlock_irqrestore(&gpio_lock, flags);
		gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
				__func__,
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
		status = -EPERM;
		goto err_unlock;
	}
	spin_unlock_irqrestore(&gpio_lock, flags);

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data) {
		status = -ENOMEM;
		goto err_unlock;
	}

	data->desc = desc;
	mutex_init(&data->mutex);
	if (chip->direction_input && chip->direction_output)
		data->direction_can_change = direction_may_change;
	else
		data->direction_can_change = false;

	offset = gpio_chip_hwgpio(desc);
	if (chip->names && chip->names[offset])
		ioname = chip->names[offset];

	dev = device_create_with_groups(&gpio_class, &gdev->dev,
					MKDEV(0, 0), data, gpio_groups,
					ioname ? ioname : "gpio%u",
					desc_to_gpio(desc));
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto err_free_data;
	}

	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

err_free_data:
	kfree(data);
err_unlock:
	mutex_unlock(&sysfs_lock);
	gpiod_dbg(desc, "%s: status %d\n", __func__, status);
	return status;
}