regmap: Add a helper function for regcache sync test

We're going to add another "does this register need syncing?" check, so
rather than repeating it in three places, we'll separate all of the
relevant logic into a helper function.
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regcache.c

@@ -249,6 +249,18 @@ int regcache_write(struct regmap *map,
 	return 0;
 }
 
+static bool regcache_reg_needs_sync(struct regmap *map, unsigned int reg,
+				    unsigned int val)
+{
+	int ret;
+
+	/* Is this the hardware default?  If so skip. */
+	ret = regcache_lookup_reg(map, reg);
+	if (ret >= 0 && val == map->reg_defaults[ret].def)
+		return false;
+	return true;
+}
+
 static int regcache_default_sync(struct regmap *map, unsigned int min,
 				 unsigned int max)
 {
@@ -266,9 +278,7 @@ static int regcache_default_sync(struct regmap *map, unsigned int min,
 		if (ret)
 			return ret;
 
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, reg);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, reg, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -613,10 +623,7 @@ static int regcache_sync_block_single(struct regmap *map, void *block,
 			continue;
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def)
+		if (!regcache_reg_needs_sync(map, regtmp, val))
 			continue;
 
 		map->cache_bypass = 1;
@@ -688,10 +695,7 @@ static int regcache_sync_block_raw(struct regmap *map, void *block,
 		}
 
 		val = regcache_get_val(map, block, i);
-
-		/* Is this the hardware default?  If so skip. */
-		ret = regcache_lookup_reg(map, regtmp);
-		if (ret >= 0 && val == map->reg_defaults[ret].def) {
+		if (!regcache_reg_needs_sync(map, regtmp, val)) {
 			ret = regcache_sync_block_raw_flush(map, &data,
 							    base, regtmp);
 			if (ret != 0)