[PATCH] Add a function to handle interrupt affinity setting

Provide funtions to:
 - check, whether an interrupt can set the affinity
 - pin the interrupt to a given cpu

Necessary for the ability to setup clocksources more flexible (e.g.  use the
different HPET channels per CPU)

[akpm@osdl.org: alpha build fix]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index cd790ad0ae57..5597c157442a 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -38,6 +38,46 @@ void synchronize_irq(unsigned int irq)
 }
 EXPORT_SYMBOL(synchronize_irq);
 
+/**
+ *      irq_can_set_affinity - Check if the affinity of a given irq can be set
+ *      @irq:           Interrupt to check
+ *
+ */
+int irq_can_set_affinity(unsigned int irq)
+{
+        struct irq_desc *desc = irq_desc + irq;
+
+        if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
+            !desc->chip->set_affinity)
+                return 0;
+
+        return 1;
+}
+
+/**
+ *      irq_set_affinity - Set the irq affinity of a given irq
+ *      @irq:           Interrupt to set affinity
+ *      @cpumask:       cpumask
+ *
+ */
+int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
+{
+        struct irq_desc *desc = irq_desc + irq;
+
+        if (!desc->chip->set_affinity)
+                return -EINVAL;
+
+        set_balance_irq_affinity(irq, cpumask);
+
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+        set_pending_irq(irq, cpumask);
+#else
+        desc->affinity = cpumask;
+        desc->chip->set_affinity(irq, cpumask);
+#endif
+        return 0;
+}
+
 #endif
 
 /**