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Commit 495c38d3 authored by David Daney's avatar David Daney Committed by Thomas Gleixner
Browse files

irqdomain: Add irq_domain_{push,pop}_irq() functions 



For an already existing irqdomain hierarchy, as might be obtained via
a call to pci_enable_msix_range(), a PCI driver wishing to add an
additional irqdomain to the hierarchy needs to be able to insert the
irqdomain to that already initialized hierarchy.  Calling
irq_domain_create_hierarchy() allows the new irqdomain to be created,
but no existing code allows for initializing the associated irq_data.

Add a couple of helper functions (irq_domain_push_irq() and
irq_domain_pop_irq()) to initialize the irq_data for the new
irqdomain added to an existing hierarchy.

Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Link: http://lkml.kernel.org/r/1503017616-3252-6-git-send-email-david.daney@cavium.com
parent 0d12ec07

include/linux/irqdomain.h

+3 −0
Original line number Diff line number Diff line
@@ -460,6 +460,9 @@ extern void irq_domain_free_irqs_common(struct irq_domain *domain, 
extern void irq_domain_free_irqs_top(struct irq_domain *domain,

				     unsigned int virq, unsigned int nr_irqs);



extern int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg);

extern int irq_domain_pop_irq(struct irq_domain *domain, int virq);



extern int irq_domain_alloc_irqs_parent(struct irq_domain *domain,

					unsigned int irq_base,

					unsigned int nr_irqs, void *arg);

kernel/irq/irqdomain.c

+169 −0
Original line number Diff line number Diff line
@@ -1449,6 +1449,175 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base, 
	return ret;

}



/* The irq_data was moved, fix the revmap to refer to the new location */

static void irq_domain_fix_revmap(struct irq_data *d)

{

	void **slot;



	if (d->hwirq < d->domain->revmap_size)

		return; /* Not using radix tree. */



	/* Fix up the revmap. */

	mutex_lock(&revmap_trees_mutex);

	slot = radix_tree_lookup_slot(&d->domain->revmap_tree, d->hwirq);

	if (slot)

		radix_tree_replace_slot(&d->domain->revmap_tree, slot, d);

	mutex_unlock(&revmap_trees_mutex);

}



/**

 * irq_domain_push_irq() - Push a domain in to the top of a hierarchy.

 * @domain:	Domain to push.

 * @virq:	Irq to push the domain in to.

 * @arg:	Passed to the irq_domain_ops alloc() function.

 *

 * For an already existing irqdomain hierarchy, as might be obtained

 * via a call to pci_enable_msix(), add an additional domain to the

 * head of the processing chain.  Must be called before request_irq()

 * has been called.

 */

int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg)

{

	struct irq_data *child_irq_data;

	struct irq_data *root_irq_data = irq_get_irq_data(virq);

	struct irq_desc *desc;

	int rv = 0;



	/*

	 * Check that no action has been set, which indicates the virq

	 * is in a state where this function doesn't have to deal with

	 * races between interrupt handling and maintaining the

	 * hierarchy.  This will catch gross misuse.  Attempting to

	 * make the check race free would require holding locks across

	 * calls to struct irq_domain_ops->alloc(), which could lead

	 * to deadlock, so we just do a simple check before starting.

	 */

	desc = irq_to_desc(virq);

	if (!desc)

		return -EINVAL;

	if (WARN_ON(desc->action))

		return -EBUSY;



	if (domain == NULL)

		return -EINVAL;



	if (WARN_ON(!irq_domain_is_hierarchy(domain)))

		return -EINVAL;



	if (domain->parent != root_irq_data->domain)

		return -EINVAL;



	if (!root_irq_data)

		return -EINVAL;



	child_irq_data = kzalloc_node(sizeof(*child_irq_data), GFP_KERNEL,

				      irq_data_get_node(root_irq_data));

	if (!child_irq_data)

		return -ENOMEM;



	mutex_lock(&irq_domain_mutex);



	/* Copy the original irq_data. */

	*child_irq_data = *root_irq_data;



	/*

	 * Overwrite the root_irq_data, which is embedded in struct

	 * irq_desc, with values for this domain.

	 */

	root_irq_data->parent_data = child_irq_data;

	root_irq_data->domain = domain;

	root_irq_data->mask = 0;

	root_irq_data->hwirq = 0;

	root_irq_data->chip = NULL;

	root_irq_data->chip_data = NULL;



	/* May (probably does) set hwirq, chip, etc. */

	rv = irq_domain_alloc_irqs_hierarchy(domain, virq, 1, arg);

	if (rv) {

		/* Restore the original irq_data. */

		*root_irq_data = *child_irq_data;

		goto error;

	}



	irq_domain_fix_revmap(child_irq_data);

	irq_domain_set_mapping(domain, root_irq_data->hwirq, root_irq_data);



error:

	mutex_unlock(&irq_domain_mutex);



	return rv;

}

EXPORT_SYMBOL_GPL(irq_domain_push_irq);



/**

 * irq_domain_pop_irq() - Remove a domain from the top of a hierarchy.

 * @domain:	Domain to remove.

 * @virq:	Irq to remove the domain from.

 *

 * Undo the effects of a call to irq_domain_push_irq().  Must be

 * called either before request_irq() or after free_irq().

 */

int irq_domain_pop_irq(struct irq_domain *domain, int virq)

{

	struct irq_data *root_irq_data = irq_get_irq_data(virq);

	struct irq_data *child_irq_data;

	struct irq_data *tmp_irq_data;

	struct irq_desc *desc;



	/*

	 * Check that no action is set, which indicates the virq is in

	 * a state where this function doesn't have to deal with races

	 * between interrupt handling and maintaining the hierarchy.

	 * This will catch gross misuse.  Attempting to make the check

	 * race free would require holding locks across calls to

	 * struct irq_domain_ops->free(), which could lead to

	 * deadlock, so we just do a simple check before starting.

	 */

	desc = irq_to_desc(virq);

	if (!desc)

		return -EINVAL;

	if (WARN_ON(desc->action))

		return -EBUSY;



	if (domain == NULL)

		return -EINVAL;



	if (!root_irq_data)

		return -EINVAL;



	tmp_irq_data = irq_domain_get_irq_data(domain, virq);



	/* We can only "pop" if this domain is at the top of the list */

	if (WARN_ON(root_irq_data != tmp_irq_data))

		return -EINVAL;



	if (WARN_ON(root_irq_data->domain != domain))

		return -EINVAL;



	child_irq_data = root_irq_data->parent_data;

	if (WARN_ON(!child_irq_data))

		return -EINVAL;



	mutex_lock(&irq_domain_mutex);



	root_irq_data->parent_data = NULL;



	irq_domain_clear_mapping(domain, root_irq_data->hwirq);

	irq_domain_free_irqs_hierarchy(domain, virq, 1);



	/* Restore the original irq_data. */

	*root_irq_data = *child_irq_data;



	irq_domain_fix_revmap(root_irq_data);



	mutex_unlock(&irq_domain_mutex);



	kfree(child_irq_data);



	return 0;

}

EXPORT_SYMBOL_GPL(irq_domain_pop_irq);



/**

 * irq_domain_free_irqs - Free IRQ number and associated data structures

 * @virq:	base IRQ number