The following commit has been merged into the irq/core branch of tip:
Commit-ID: 55567976629e58fde28fb70612ca73228271eef2
Gitweb:
https://git.kernel.org/tip/55567976629e58fde28fb70612ca73228271eef2
Author: Marc Zyngier <m...@kernel.org>
AuthorDate: Tue, 06 Oct 2020 10:10:20 +01:00
Committer: Marc Zyngier <m...@kernel.org>
CommitterDate: Sat, 10 Oct 2020 12:12:10 +01:00
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 <m...@kernel.org>
---
include/linux/irqdomain.h | 3 +-
kernel/irq/irqdomain.c | 99 +++++++++++++++++++++++++++++++++++--
2 files changed, 98 insertions(+), 4 deletions(-)
diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index b37350c..a52b095 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -509,6 +509,9 @@ extern void irq_domain_free_irqs_parent(struct irq_domain
*domain,
unsigned int irq_base,
unsigned int nr_irqs);
+extern int irq_domain_disconnect_hierarchy(struct irq_domain *domain,
+ unsigned int virq);
+
static inline bool irq_domain_is_hierarchy(struct irq_domain *domain)
{
return domain->flags & IRQ_DOMAIN_FLAG_HIERARCHY;
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 76cd7eb..cf8b374 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);
