regmap: Allow multiple patches to be registered

It may be useful to register multiple patches with regmap, for example
one that depends on the device revision and one that depends on the system
configuration. Add support for doing this, appending any new patches to
the existing patches.
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/regmap.c

@@ -1888,13 +1888,10 @@ EXPORT_SYMBOL_GPL(regmap_async_complete);
 int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
 			  int num_regs)
 {
+	struct reg_default *p;
 	int i, ret;
 	bool bypass;
 
-	/* If needed the implementation can be extended to support this */
-	if (map->patch)
-		return -EBUSY;
-
 	map->lock(map->lock_arg);
 
 	bypass = map->cache_bypass;
@@ -1911,11 +1908,13 @@ int regmap_register_patch(struct regmap *map, const struct reg_default *regs,
 		}
 	}
 
-	map->patch = kcalloc(num_regs, sizeof(struct reg_default), GFP_KERNEL);
-	if (map->patch != NULL) {
-		memcpy(map->patch, regs,
-		       num_regs * sizeof(struct reg_default));
-		map->patch_regs = num_regs;
+	p = krealloc(map->patch,
+		     sizeof(struct reg_default) * (map->patch_regs + num_regs),
+		     GFP_KERNEL);
+	if (p) {
+		memcpy(p + map->patch_regs, regs, num_regs * sizeof(*regs));
+		map->patch = p;
+		map->patch_regs += num_regs;
 	} else {
 		ret = -ENOMEM;
 	}