sh: intc: optimize intc IRQ lookup

This ensures that the sense/prio lists are sorted at registration time,
enabling us to use a simple binary search for an optimized lookup
(something that had been on the TODO for some time).

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 6 insertions, 21 deletions

diff --git a/drivers/sh/intc/chip.c b/drivers/sh/intc/chip.c
index db10adf63dd7..012df2676a26 100644
--- a/drivers/sh/intc/chip.c
+++ b/drivers/sh/intc/chip.c
@@ -2,13 +2,14 @@
  * IRQ chip definitions for INTC IRQs.
  *
  * Copyright (C) 2007, 2008 Magnus Damm
- * Copyright (C) 2009, 2010 Paul Mundt
+ * Copyright (C) 2009 - 2012 Paul Mundt
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  */
 #include <linux/cpumask.h>
+#include <linux/bsearch.h>
 #include <linux/io.h>
 #include "internals.h"
 
@@ -117,28 +118,12 @@ static struct intc_handle_int *intc_find_irq(struct intc_handle_int *hp,
                                              unsigned int nr_hp,
                                              unsigned int irq)
 {
-        int i;
-
-        /*
-         * this doesn't scale well, but...
-         *
-         * this function should only be used for cerain uncommon
-         * operations such as intc_set_priority() and intc_set_type()
-         * and in those rare cases performance doesn't matter that much.
-         * keeping the memory footprint low is more important.
-         *
-         * one rather simple way to speed this up and still keep the
-         * memory footprint down is to make sure the array is sorted
-         * and then perform a bisect to lookup the irq.
-         */
-        for (i = 0; i < nr_hp; i++) {
-                if ((hp + i)->irq != irq)
-                        continue;
+        struct intc_handle_int key;
 
-                return hp + i;
-        }
+        key.irq = irq;
+        key.handle = 0;
 
-        return NULL;
+        return bsearch(&key, hp, nr_hp, sizeof(*hp), intc_handle_int_cmp);
 }
 
 int intc_set_priority(unsigned int irq, unsigned int prio)