regmap: Implement writable register checks

This is mainly intended to be used by devices which can dynamically
block register writes at runtime, for other devices there is usually
limited value.

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

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 7d4dc11..e57f10f 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -211,6 +211,13 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
        void *buf;
        int ret = -ENOTSUPP;
        size_t len;
+       int i;
+
+       /* Check for unwritable registers before we start */
+       if (map->writeable_reg)
+               for (i = 0; i < val_len / map->format.val_bytes; i++)
+                       if (!map->writeable_reg(map->dev, reg + i))
+                               return -EINVAL;
 
        map->format.format_reg(map->work_buf, reg);