regmap: Optimize the lookup path to use binary search

Since there are more lookups than insertions in a typical
scenario, optimize the linear search into a binary search.  For
this to work, we need to keep reg_defaults sorted upon
insertions, for now be lazy and use sort().

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 2d55b261f1c50db138aa0d59380590ea84128f63..e1846eb2f171fa0b12714cc0fdd74796da6e42dd 100644 (file)
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -12,6 +12,7 @@
 
 #include <linux/slab.h>
 #include <trace/events/regmap.h>
+#include <linux/sort.h>
 
 #include "internal.h"
 
@@ -356,14 +357,30 @@ unsigned int regcache_get_val(const void *base, unsigned int idx,
 
 int regcache_lookup_reg(struct regmap *map, unsigned int reg)
 {
-       unsigned int i;
-
-       for (i = 0; i < map->num_reg_defaults; i++)
-               if (map->reg_defaults[i].reg == reg)
-                       return i;
+       unsigned int min, max, index;
+
+       min = 0;
+       max = map->num_reg_defaults - 1;
+       do {
+               index = (min + max) / 2;
+               if (map->reg_defaults[index].reg == reg)
+                       return index;
+               if (map->reg_defaults[index].reg < reg)
+                       min = index + 1;
+               else
+                       max = index;
+       } while (min <= max);
        return -1;
 }
 
+static int regcache_insert_cmp(const void *a, const void *b)
+{
+       const struct reg_default *_a = a;
+       const struct reg_default *_b = b;
+
+       return _a->reg - _b->reg;
+}
+
 int regcache_insert_reg(struct regmap *map, unsigned int reg,
                        unsigned int val)
 {
@@ -378,5 +395,7 @@ int regcache_insert_reg(struct regmap *map, unsigned int reg,
        map->num_reg_defaults++;
        map->reg_defaults[map->num_reg_defaults - 1].reg = reg;
        map->reg_defaults[map->num_reg_defaults - 1].def = val;
+       sort(map->reg_defaults, map->num_reg_defaults,
+            sizeof(struct reg_default), regcache_insert_cmp, NULL);
        return 0;
 }