ASoC: Add helper functions for deferred regmap setup

Some drivers (most notably the AC'97 drivers) do not have access to their
regmap struct when the component/codec is registered. For those drivers the
automatic regmap setup will not work and needs to be done manually,
typically from the component/CODEC drivers probe callback.

This patch adds a set of helper function to handle deferred regmap
initialization as well as early regmap tear-down.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/include/sound/soc.h b/include/sound/soc.h
index 7ba7130..342b43b 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -1277,6 +1277,41 @@
 int snd_soc_component_test_bits(struct snd_soc_component *component,
 	unsigned int reg, unsigned int mask, unsigned int value);
 
+void snd_soc_component_init_regmap(struct snd_soc_component *component,
+	struct regmap *regmap);
+void snd_soc_component_exit_regmap(struct snd_soc_component *component);
+
+/**
+ * snd_soc_codec_init_regmap() - Initialize regmap instance for the CODEC
+ * @codec: The CODEC for which to initialize the regmap instance
+ * @regmap: The regmap instance that should be used by the CODEC
+ *
+ * This function allows deferred assignment of the regmap instance that is
+ * associated with the CODEC. Only use this if the regmap instance is not yet
+ * ready when the CODEC is registered. The function must also be called before
+ * the first IO attempt of the CODEC.
+ */
+static inline void snd_soc_codec_init_regmap(struct snd_soc_codec *codec,
+	struct regmap *regmap)
+{
+	snd_soc_component_init_regmap(&codec->component, regmap);
+}
+
+/**
+ * snd_soc_codec_exit_regmap() - De-initialize regmap instance for the CODEC
+ * @codec: The CODEC for which to de-initialize the regmap instance
+ *
+ * Calls regmap_exit() on the regmap instance associated to the CODEC and
+ * removes the regmap instance from the CODEC.
+ *
+ * This function should only be used if snd_soc_codec_init_regmap() was used to
+ * initialize the regmap instance.
+ */
+static inline void snd_soc_codec_exit_regmap(struct snd_soc_codec *codec)
+{
+	snd_soc_component_exit_regmap(&codec->component);
+}
+
 /* device driver data */
 
 static inline void snd_soc_card_set_drvdata(struct snd_soc_card *card,