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>

include/sound/soc.h

@@ -278,6 +278,10 @@ int snd_soc_register_codec(struct device *dev,
 void snd_soc_unregister_codec(struct device *dev);
 int snd_soc_codec_volatile_register(struct snd_soc_codec *codec,
 				    unsigned int reg);
+int snd_soc_codec_readable_register(struct snd_soc_codec *codec,
+				    unsigned int reg);
+int snd_soc_codec_writable_register(struct snd_soc_codec *codec,
+				    unsigned int reg);
 int snd_soc_codec_set_cache_io(struct snd_soc_codec *codec,
 			       int addr_bits, int data_bits,
 			       enum snd_soc_control_type control);

sound/soc/soc-core.c

@@ -2146,6 +2146,42 @@ int snd_soc_codec_volatile_register(struct snd_soc_codec *codec,
 }
 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