regmap: Support some more block operations on cached devices

Commit 10a08d9f ("regmap: Support some block operations on cached devices")
allowed raw read operations without throwing a warning when using caches if
all registers are volatile. This patch does the same for raw write operations.

This is for example useful when loading a firmware in a predefined volatile
region on a chip where we otherwise want registers to be cached.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/regmap.c

@@ -389,9 +389,11 @@ EXPORT_SYMBOL_GPL(regmap_write);
 int regmap_raw_write(struct regmap *map, unsigned int reg,
 		     const void *val, size_t val_len)
 {
+	size_t val_count = val_len / map->format.val_bytes;
 	int ret;
 
-	WARN_ON(map->cache_type != REGCACHE_NONE);
+	WARN_ON(!regmap_volatile_range(map, reg, val_count) &&
+		map->cache_type != REGCACHE_NONE);
 
 	mutex_lock(&map->lock);