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>

include/sound/soc.h

@@ -292,6 +292,8 @@ int snd_soc_default_volatile_register(struct snd_soc_codec *codec,
 				      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 @@ struct snd_soc_codec {
 	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 @@ struct snd_soc_codec_driver {
 				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;

sound/soc/soc-cache.c

@@ -1449,3 +1449,17 @@ int snd_soc_default_readable_register(struct snd_soc_codec *codec,
 	return codec->driver->reg_access_default[index].read;
 }
 EXPORT_SYMBOL_GPL(snd_soc_default_readable_register);
+
+int snd_soc_default_writable_register(struct snd_soc_codec *codec,
+				      unsigned int reg)
+{
+	int index;
+
+	if (reg >= codec->driver->reg_cache_size)
+		return 1;
+	index = snd_soc_get_reg_access_index(codec, reg);
+	if (index < 0)
+		return 0;
+	return codec->driver->reg_access_default[index].write;
+}
+EXPORT_SYMBOL_GPL(snd_soc_default_writable_register);

sound/soc/soc-core.c

@@ -3673,6 +3673,7 @@ int snd_soc_register_codec(struct device *dev,
 	codec->read = codec_drv->read;
 	codec->volatile_register = codec_drv->volatile_register;
 	codec->readable_register = codec_drv->readable_register;
+	codec->writable_register = codec_drv->writable_register;
 	codec->dapm.bias_level = SND_SOC_BIAS_OFF;
 	codec->dapm.dev = dev;
 	codec->dapm.codec = codec;
@@ -3707,6 +3708,8 @@ int snd_soc_register_codec(struct device *dev,
 			codec->volatile_register = snd_soc_default_volatile_register;
 		if (!codec->readable_register)
 			codec->readable_register = snd_soc_default_readable_register;
+		if (!codec->writable_register)
+			codec->writable_register = snd_soc_default_writable_register;
 	}
 
 	for (i = 0; i < num_dai; i++) {