ASoC: arizona: Add utility function to check if an input is analog

We will occasionally require to take different action based on if an
input is analog or digital so add a helper function to return if an
input is analog.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/arizona.c

@@ -691,6 +691,15 @@ static void arizona_in_set_vu(struct snd_soc_codec *codec, int ena)
 				    ARIZONA_IN_VU, val);
 }
 
+bool arizona_input_analog(struct snd_soc_codec *codec, int shift)
+{
+	unsigned int reg = ARIZONA_IN1L_CONTROL + ((shift / 2) * 8);
+	unsigned int val = snd_soc_read(codec, reg);
+
+	return !(val & ARIZONA_IN1_MODE_MASK);
+}
+EXPORT_SYMBOL_GPL(arizona_input_analog);
+
 int arizona_in_ev(struct snd_soc_dapm_widget *w, struct snd_kcontrol *kcontrol,
 		  int event)
 {