ASoC: Add default snd_soc_default_writable_register() callback

By using struct snd_soc_reg_access for the read/write/vol attributes
of the registers, we provide callbacks that automatically determine whether
a given register is readable/writable or volatile.

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/include/sound/soc.h b/include/sound/soc.h
index 4a11795..e208357 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -292,6 +292,8 @@
 				      unsigned int reg);
 int snd_soc_default_readable_register(struct snd_soc_codec *codec,
 				      unsigned int reg);
+int snd_soc_default_writable_register(struct snd_soc_codec *codec,
+				      unsigned int reg);
 
 /* Utility functions to get clock rates from various things */
 int snd_soc_calc_frame_size(int sample_size, int channels, int tdm_slots);
@@ -523,6 +525,7 @@
 	size_t reg_size;	/* reg_cache_size * reg_word_size */
 	int (*volatile_register)(struct snd_soc_codec *, unsigned int);
 	int (*readable_register)(struct snd_soc_codec *, unsigned int);
+	int (*writable_register)(struct snd_soc_codec *, unsigned int);
 
 	/* runtime */
 	struct snd_ac97 *ac97;  /* for ad-hoc ac97 devices */
@@ -589,6 +592,7 @@
 				size_t, unsigned int);
 	int (*volatile_register)(struct snd_soc_codec *, unsigned int);
 	int (*readable_register)(struct snd_soc_codec *, unsigned int);
+	int (*writable_register)(struct snd_soc_codec *, unsigned int);
 	short reg_cache_size;
 	short reg_cache_step;
 	short reg_word_size;