regmap: rbtree: Simplify adjacent node look-up

A register which is adjacent to a node will either be left to the first
register or right to the last register. It will not be within the node's range,
so there is no point in checking for each register cached by the node whether
the new register is next to it. It is sufficient to check whether the register
comes before the first register or after the last register of the node.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/regcache-rbtree.c

@@ -352,9 +352,9 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 	struct regcache_rbtree_ctx *rbtree_ctx;
 	struct regcache_rbtree_node *rbnode, *rbnode_tmp;
 	struct rb_node *node;
+	unsigned int base_reg, top_reg;
 	unsigned int reg_tmp;
 	unsigned int pos;
-	int i;
 	int ret;
 
 	rbtree_ctx = map->cache;
@@ -376,26 +376,25 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 		     node = rb_next(node)) {
 			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 					      node);
-			for (i = 0; i < rbnode_tmp->blklen; i++) {
-				reg_tmp = rbnode_tmp->base_reg +
-						(i * map->reg_stride);
-				if (abs(reg_tmp - reg) != map->reg_stride)
-					continue;
+
+			regcache_rbtree_get_base_top_reg(map, rbnode_tmp,
+				&base_reg, &top_reg);
+
 			/* decide where in the block to place our register */
-				if (reg_tmp + map->reg_stride == reg)
-					pos = i + 1;
+			if (base_reg > 0 && reg == base_reg - map->reg_stride)
+				pos = 0;
+			else if (reg > 0 && reg - map->reg_stride == top_reg)
+				pos = rbnode_tmp->blklen;
 			else
-					pos = i;
-				ret = regcache_rbtree_insert_to_block(map,
-								      rbnode_tmp,
-								      pos, reg,
-								      value);
+				continue;
+
+			ret = regcache_rbtree_insert_to_block(map, rbnode_tmp,
+							      pos, reg, value);
 			if (ret)
 				return ret;
 			rbtree_ctx->cached_rbnode = rbnode_tmp;
 			return 0;
 		}
-		}
 
 		/* We did not manage to find a place to insert it in
 		 * an existing block so create a new rbnode.