[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>

3 files changed, 51 insertions, 21 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 8930fb0ac9c7..29f715e71bdd 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -238,11 +238,21 @@ static inline void set_pending_irq(unsigned int irq, cpumask_t mask)
 
 #endif /* CONFIG_GENERIC_PENDING_IRQ */
 
+extern int irq_set_affinity(unsigned int irq, cpumask_t cpumask);
+extern int irq_can_set_affinity(unsigned int irq);
+
 #else /* CONFIG_SMP */
 
 #define move_native_irq(x)
 #define move_masked_irq(x)
 
+static inline int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
+{
+        return -EINVAL;
+}
+
+static inline int irq_can_set_affinity(unsigned int irq) { return 0; }
+
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_IRQBALANCE
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
 
 /**
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index bb44bc995d6e..2db91eb54ad8 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -16,26 +16,6 @@ static struct proc_dir_entry *root_irq_dir;
 
 #ifdef CONFIG_SMP
 
-#ifdef CONFIG_GENERIC_PENDING_IRQ
-void proc_set_irq_affinity(unsigned int irq, cpumask_t mask_val)
-{
-        set_balance_irq_affinity(irq, mask_val);
-
-        /*
-         * Save these away for later use. Re-progam when the
-         * interrupt is pending
-         */
-        set_pending_irq(irq, mask_val);
-}
-#else
-void proc_set_irq_affinity(unsigned int irq, cpumask_t mask_val)
-{
-        set_balance_irq_affinity(irq, mask_val);
-        irq_desc[irq].affinity = mask_val;
-        irq_desc[irq].chip->set_affinity(irq, mask_val);
-}
-#endif
-
 static int irq_affinity_read_proc(char *page, char **start, off_t off,
                                   int count, int *eof, void *data)
 {
@@ -73,7 +53,7 @@ static int irq_affinity_write_proc(struct file *file, const char __user *buffer,
                    code to set default SMP affinity. */
                 return select_smp_affinity(irq) ? -EINVAL : full_count;
 
-        proc_set_irq_affinity(irq, new_value);
+        irq_set_affinity(irq, new_value);
 
         return full_count;
 }