int pnp_check_irq()

in resource.c [352:413]

• 45 lines of code
• 17 McCabe index (conditional complexity)

int pnp_check_irq(struct pnp_dev *dev, struct resource *res)
{
	int i;
	struct pnp_dev *tdev;
	struct resource *tres;
	resource_size_t *irq;

	irq = &res->start;

	/* if the resource doesn't exist, don't complain about it */
	if (cannot_compare(res->flags))
		return 1;

	/* check if the resource is valid */
	if (*irq > 15)
		return 0;

	/* check if the resource is reserved */
	for (i = 0; i < 16; i++) {
		if (pnp_reserve_irq[i] == *irq)
			return 0;
	}

	/* check for internal conflicts */
	for (i = 0; (tres = pnp_get_resource(dev, IORESOURCE_IRQ, i)); i++) {
		if (tres != res && tres->flags & IORESOURCE_IRQ) {
			if (tres->start == *irq)
				return 0;
		}
	}

	/* check if the resource is being used by a pci device */
	if (pci_uses_irq(dev, *irq))
		return 0;

	/* check if the resource is already in use, skip if the
	 * device is active because it itself may be in use */
	if (!dev->active) {
		if (request_irq(*irq, pnp_test_handler,
				IRQF_PROBE_SHARED, "pnp", NULL))
			return 0;
		free_irq(*irq, NULL);
	}

	/* check for conflicts with other pnp devices */
	pnp_for_each_dev(tdev) {
		if (tdev == dev)
			continue;
		for (i = 0;
		     (tres = pnp_get_resource(tdev, IORESOURCE_IRQ, i));
		     i++) {
			if (tres->flags & IORESOURCE_IRQ) {
				if (cannot_compare(tres->flags))
					continue;
				if (tres->start == *irq)
					return 0;
			}
		}
	}

	return 1;
}