[PATCH 1/3] genirq/affinity: Add irq_update_affinity_desc()

[John Garry <john.garry@huawei.com>]

From: Thomas Gleixner <tglx@linutronix.de>

Add a function to allow the affinity of an interrupt be switched to
managed, such that interrupts allocated for platform devices may be
managed.

<Insert author sob>
[jpg: Add commit message and add prototypes]
Signed-off-by: John Garry <john.garry@huawei.com>
---
Thomas, I just made you author since you provided the original code, hope
it's ok.

 include/linux/interrupt.h |  8 ++++++++
 kernel/irq/manage.c       | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index ee8299eb1f52..870b3251e174 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -352,6 +352,8 @@ extern int irq_can_set_affinity(unsigned int irq);
 extern int irq_select_affinity(unsigned int irq);
 
 extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
+extern int irq_update_affinity_desc(unsigned int irq,
+				    struct irq_affinity_desc *affinity);
 
 extern int
 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
@@ -387,6 +389,12 @@ static inline int irq_set_affinity_hint(unsigned int irq,
 	return -EINVAL;
 }
 
+static inline int irq_update_affinity_desc(unsigned int irq,
+					   struct irq_affinity_desc *affinity)
+{
+	return -EINVAL;
+}
+
 static inline int
 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 {
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c460e0496006..b96af4cde4bc 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -371,6 +371,25 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
 	return ret;
 }
 
+int irq_update_affinity_desc(unsigned int irq,
+			     struct irq_affinity_desc *affinity)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
+
+	if (!desc)
+		return -EINVAL;
+
+	if (affinity->is_managed) {
+		irqd_set(&desc->irq_data, IRQD_AFFINITY_MANAGED);
+		irqd_set(&desc->irq_data, IRQD_MANAGED_SHUTDOWN);
+	}
+
+	cpumask_copy(desc->irq_common_data.affinity, &affinity->mask);
+	irq_put_desc_unlock(desc, flags);
+	return 0;
+}
+
 int __irq_set_affinity(unsigned int irq, const struct cpumask *mask, bool force)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
-- 
2.26.2