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genirq/irqdomain: Allow partial trimming of irq_data hierarchy
It appears that some HW is ugly enough that not all the interrupts connected to a particular interrupt controller end up with the same hierarchy depth (some of them are terminated early). This leaves the irqchip hacker with only two choices, both equally bad: - create discrete domain chains, one for each "hierarchy depth", which is very hard to maintain - create fake hierarchy levels for the shallow paths, leading to all kind of problems (what are the safe hwirq values for these fake levels?) Implement the ability to cut short a single interrupt hierarchy from a level marked as being disconnected by using the new irq_domain_disconnect_hierarchy() helper. The irqdomain allocation code will then perform the trimming Signed-off-by: Marc Zyngier <maz@kernel.org>
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@ -509,6 +509,9 @@ extern void irq_domain_free_irqs_parent(struct irq_domain *domain,
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unsigned int irq_base,
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unsigned int nr_irqs);
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extern int irq_domain_disconnect_hierarchy(struct irq_domain *domain,
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unsigned int virq);
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static inline bool irq_domain_is_hierarchy(struct irq_domain *domain)
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{
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return domain->flags & IRQ_DOMAIN_FLAG_HIERARCHY;
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@ -1136,6 +1136,17 @@ static struct irq_data *irq_domain_insert_irq_data(struct irq_domain *domain,
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return irq_data;
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}
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static void __irq_domain_free_hierarchy(struct irq_data *irq_data)
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{
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struct irq_data *tmp;
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while (irq_data) {
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tmp = irq_data;
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irq_data = irq_data->parent_data;
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kfree(tmp);
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}
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}
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static void irq_domain_free_irq_data(unsigned int virq, unsigned int nr_irqs)
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{
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struct irq_data *irq_data, *tmp;
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@ -1147,12 +1158,83 @@ static void irq_domain_free_irq_data(unsigned int virq, unsigned int nr_irqs)
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irq_data->parent_data = NULL;
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irq_data->domain = NULL;
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while (tmp) {
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irq_data = tmp;
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tmp = tmp->parent_data;
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kfree(irq_data);
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__irq_domain_free_hierarchy(tmp);
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}
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}
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/**
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* irq_domain_disconnect_hierarchy - Mark the first unused level of a hierarchy
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* @domain: IRQ domain from which the hierarchy is to be disconnected
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* @virq: IRQ number where the hierarchy is to be trimmed
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*
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* Marks the @virq level belonging to @domain as disconnected.
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* Returns -EINVAL if @virq doesn't have a valid irq_data pointing
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* to @domain.
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*
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* Its only use is to be able to trim levels of hierarchy that do not
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* have any real meaning for this interrupt, and that the driver marks
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* as such from its .alloc() callback.
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*/
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int irq_domain_disconnect_hierarchy(struct irq_domain *domain,
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unsigned int virq)
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{
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struct irq_data *irqd;
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irqd = irq_domain_get_irq_data(domain, virq);
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if (!irqd)
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return -EINVAL;
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irqd->chip = ERR_PTR(-ENOTCONN);
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return 0;
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}
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static int irq_domain_trim_hierarchy(unsigned int virq)
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{
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struct irq_data *tail, *irqd, *irq_data;
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irq_data = irq_get_irq_data(virq);
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tail = NULL;
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/* The first entry must have a valid irqchip */
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if (!irq_data->chip || IS_ERR(irq_data->chip))
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return -EINVAL;
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/*
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* Validate that the irq_data chain is sane in the presence of
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* a hierarchy trimming marker.
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*/
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for (irqd = irq_data->parent_data; irqd; irq_data = irqd, irqd = irqd->parent_data) {
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/* Can't have a valid irqchip after a trim marker */
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if (irqd->chip && tail)
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return -EINVAL;
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/* Can't have an empty irqchip before a trim marker */
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if (!irqd->chip && !tail)
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return -EINVAL;
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if (IS_ERR(irqd->chip)) {
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/* Only -ENOTCONN is a valid trim marker */
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if (PTR_ERR(irqd->chip) != -ENOTCONN)
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return -EINVAL;
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tail = irq_data;
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}
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}
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/* No trim marker, nothing to do */
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if (!tail)
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return 0;
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pr_info("IRQ%d: trimming hierarchy from %s\n",
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virq, tail->parent_data->domain->name);
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/* Sever the inner part of the hierarchy... */
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irqd = tail;
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tail = tail->parent_data;
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irqd->parent_data = NULL;
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__irq_domain_free_hierarchy(tail);
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return 0;
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}
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static int irq_domain_alloc_irq_data(struct irq_domain *domain,
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@ -1362,6 +1444,15 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
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mutex_unlock(&irq_domain_mutex);
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goto out_free_irq_data;
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}
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for (i = 0; i < nr_irqs; i++) {
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ret = irq_domain_trim_hierarchy(virq + i);
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if (ret) {
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mutex_unlock(&irq_domain_mutex);
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goto out_free_irq_data;
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}
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}
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for (i = 0; i < nr_irqs; i++)
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irq_domain_insert_irq(virq + i);
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mutex_unlock(&irq_domain_mutex);
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