ASoC: Allow CODECs to flag invalid registers

This helps CODECs with sparse register maps work better with the
register cache display interface.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 756fb59772d1..55b330937260 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -385,6 +385,7 @@ struct snd_soc_codec {
         int (*display_register)(struct snd_soc_codec *, char *,
                                 size_t, unsigned int);
         int (*volatile_register)(unsigned int);
+        int (*readable_register)(unsigned int);
         hw_write_t hw_write;
         hw_read_t hw_read;
         void *reg_cache;