ASoC: Add snd_soc_codec_{readable,writable}_register()

Provide the top level ASoC core functions for indicating whether
a given register is readable or writable.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 074a0c6..5ae70a10 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2147,6 +2147,42 @@
 EXPORT_SYMBOL_GPL(snd_soc_codec_volatile_register);
 
 /**
+ * snd_soc_codec_readable_register: Report if a register is readable.
+ *
+ * @codec: CODEC to query.
+ * @reg: Register to query.
+ *
+ * Boolean function indicating if a CODEC register is readable.
+ */
+int snd_soc_codec_readable_register(struct snd_soc_codec *codec,
+				    unsigned int reg)
+{
+	if (codec->readable_register)
+		return codec->readable_register(codec, reg);
+	else
+		return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_codec_readable_register);
+
+/**
+ * snd_soc_codec_writable_register: Report if a register is writable.
+ *
+ * @codec: CODEC to query.
+ * @reg: Register to query.
+ *
+ * Boolean function indicating if a CODEC register is writable.
+ */
+int snd_soc_codec_writable_register(struct snd_soc_codec *codec,
+				    unsigned int reg)
+{
+	if (codec->writable_register)
+		return codec->writable_register(codec, reg);
+	else
+		return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_codec_writable_register);
+
+/**
  * snd_soc_new_ac97_codec - initailise AC97 device
  * @codec: audio codec
  * @ops: AC97 bus operations