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authorMarc Zyngier <maz@kernel.org>2020-10-06 10:10:20 +0100
committerMarc Zyngier <maz@kernel.org>2020-10-10 12:12:10 +0100
commit55567976629e58fde28fb70612ca73228271eef2 (patch)
treef926a199d71a6785560771ef72599570dccc8251 /kernel/irq
parentf4d51dffc6c01a9e94650d95ce0104964f8ae822 (diff)
downloadlinux-stericsson-55567976629e58fde28fb70612ca73228271eef2.tar.gz
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>
Diffstat (limited to 'kernel/irq')
-rw-r--r--kernel/irq/irqdomain.c99
1 files changed, 95 insertions, 4 deletions
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 76cd7ebd1178..cf8b374b892d 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1136,6 +1136,17 @@ static struct irq_data *irq_domain_insert_irq_data(struct irq_domain *domain,
return irq_data;
}
+static void __irq_domain_free_hierarchy(struct irq_data *irq_data)
+{
+ struct irq_data *tmp;
+
+ while (irq_data) {
+ tmp = irq_data;
+ irq_data = irq_data->parent_data;
+ kfree(tmp);
+ }
+}
+
static void irq_domain_free_irq_data(unsigned int virq, unsigned int nr_irqs)
{
struct irq_data *irq_data, *tmp;
@@ -1147,12 +1158,83 @@ static void irq_domain_free_irq_data(unsigned int virq, unsigned int nr_irqs)
irq_data->parent_data = NULL;
irq_data->domain = NULL;
- while (tmp) {
- irq_data = tmp;
- tmp = tmp->parent_data;
- kfree(irq_data);
+ __irq_domain_free_hierarchy(tmp);
+ }
+}
+
+/**
+ * irq_domain_disconnect_hierarchy - Mark the first unused level of a hierarchy
+ * @domain: IRQ domain from which the hierarchy is to be disconnected
+ * @virq: IRQ number where the hierarchy is to be trimmed
+ *
+ * Marks the @virq level belonging to @domain as disconnected.
+ * Returns -EINVAL if @virq doesn't have a valid irq_data pointing
+ * to @domain.
+ *
+ * Its only use is to be able to trim levels of hierarchy that do not
+ * have any real meaning for this interrupt, and that the driver marks
+ * as such from its .alloc() callback.
+ */
+int irq_domain_disconnect_hierarchy(struct irq_domain *domain,
+ unsigned int virq)
+{
+ struct irq_data *irqd;
+
+ irqd = irq_domain_get_irq_data(domain, virq);
+ if (!irqd)
+ return -EINVAL;
+
+ irqd->chip = ERR_PTR(-ENOTCONN);
+ return 0;
+}
+
+static int irq_domain_trim_hierarchy(unsigned int virq)
+{
+ struct irq_data *tail, *irqd, *irq_data;
+
+ irq_data = irq_get_irq_data(virq);
+ tail = NULL;
+
+ /* The first entry must have a valid irqchip */
+ if (!irq_data->chip || IS_ERR(irq_data->chip))
+ return -EINVAL;
+
+ /*
+ * Validate that the irq_data chain is sane in the presence of
+ * a hierarchy trimming marker.
+ */
+ for (irqd = irq_data->parent_data; irqd; irq_data = irqd, irqd = irqd->parent_data) {
+ /* Can't have a valid irqchip after a trim marker */
+ if (irqd->chip && tail)
+ return -EINVAL;
+
+ /* Can't have an empty irqchip before a trim marker */
+ if (!irqd->chip && !tail)
+ return -EINVAL;
+
+ if (IS_ERR(irqd->chip)) {
+ /* Only -ENOTCONN is a valid trim marker */
+ if (PTR_ERR(irqd->chip) != -ENOTCONN)
+ return -EINVAL;
+
+ tail = irq_data;
}
}
+
+ /* No trim marker, nothing to do */
+ if (!tail)
+ return 0;
+
+ pr_info("IRQ%d: trimming hierarchy from %s\n",
+ virq, tail->parent_data->domain->name);
+
+ /* Sever the inner part of the hierarchy... */
+ irqd = tail;
+ tail = tail->parent_data;
+ irqd->parent_data = NULL;
+ __irq_domain_free_hierarchy(tail);
+
+ return 0;
}
static int irq_domain_alloc_irq_data(struct irq_domain *domain,
@@ -1362,6 +1444,15 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
mutex_unlock(&irq_domain_mutex);
goto out_free_irq_data;
}
+
+ for (i = 0; i < nr_irqs; i++) {
+ ret = irq_domain_trim_hierarchy(virq + i);
+ if (ret) {
+ mutex_unlock(&irq_domain_mutex);
+ goto out_free_irq_data;
+ }
+ }
+
for (i = 0; i < nr_irqs; i++)
irq_domain_insert_irq(virq + i);
mutex_unlock(&irq_domain_mutex);