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    Subject[PATCH v5 3/6] irqdomain: Add irq_domain_{push,pop}_irq() functions.
    Date
    For an already existing irqdomain hierarchy, as might be obtained via
    a call to pci_enable_msix(), 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()
    irq_domain_pop_irq()) to initialize the irq_data for the new
    irqdomain.

    Signed-off-by: David Daney <david.daney@cavium.com>
    ---
    include/linux/irqdomain.h | 3 +
    kernel/irq/irqdomain.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++
    2 files changed, 140 insertions(+)

    diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
    index 188eced..a7a16b7 100644
    --- a/include/linux/irqdomain.h
    +++ b/include/linux/irqdomain.h
    @@ -425,6 +425,9 @@ 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);
    diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
    index 31805f2..d5d1c01 100644
    --- a/kernel/irq/irqdomain.c
    +++ b/kernel/irq/irqdomain.c
    @@ -1304,6 +1304,143 @@ 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.
    + */
    +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);
    +
    + if (domain == NULL)
    + return -EINVAL;
    +
    + if (WARN_ON(!domain->ops->alloc))
    + 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;
    +
    + irq_domain_fix_revmap(child_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;
    + domain->ops->alloc(domain, virq, 1, arg);
    +
    + if (root_irq_data->hwirq < domain->revmap_size) {
    + domain->linear_revmap[root_irq_data->hwirq] = virq;
    + } else {
    + mutex_lock(&revmap_trees_mutex);
    + radix_tree_insert(&domain->revmap_tree,
    + root_irq_data->hwirq, root_irq_data);
    + mutex_unlock(&revmap_trees_mutex);
    + }
    +
    + mutex_unlock(&irq_domain_mutex);
    +
    + return 0;
    +}
    +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().
    + */
    +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;
    +
    + 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;
    +
    + if (root_irq_data->hwirq >= domain->revmap_size) {
    + mutex_lock(&revmap_trees_mutex);
    + radix_tree_delete(&domain->revmap_tree, root_irq_data->hwirq);
    + mutex_unlock(&revmap_trees_mutex);
    + }
    +
    + if (domain->ops->free)
    + domain->ops->free(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
    --
    1.8.3.1
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