ASoC: Automatically manage DAC deemphasis rate for WM8960

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>

sound/soc/codecs/wm8960.c

@@ -79,6 +79,8 @@ struct wm8960_priv {
 	struct snd_soc_dapm_widget *lout1;
 	struct snd_soc_dapm_widget *rout1;
 	struct snd_soc_dapm_widget *out3;
+	bool deemph;
+	int playback_fs;
 };
 
 #define wm8960_reset(c)	snd_soc_write(c, WM8960_RESET, 0)
@@ -100,6 +102,59 @@ static const struct soc_enum wm8960_enum[] = {
 	SOC_ENUM_SINGLE(WM8960_ALC3, 8, 2, wm8960_alcmode),
 };
 
+static const int deemph_settings[] = { 0, 32000, 44100, 48000 };
+
+static int wm8960_set_deemph(struct snd_soc_codec *codec)
+{
+	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
+	int val, i, best;
+
+	/* If we're using deemphasis select the nearest available sample
+	 * rate.
+	 */
+	if (wm8960->deemph) {
+		best = 1;
+		for (i = 2; i < ARRAY_SIZE(deemph_settings); i++) {
+			if (abs(deemph_settings[i] - wm8960->playback_fs) <
+			    abs(deemph_settings[best] - wm8960->playback_fs))
+				best = i;
+		}
+
+		val = best << 1;
+	} else {
+		val = 0;
+	}
+
+	dev_dbg(codec->dev, "Set deemphasis %d\n", val);
+
+	return snd_soc_update_bits(codec, WM8960_DACCTL1,
+				   0x6, val);
+}
+
+static int wm8960_get_deemph(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
+
+	return wm8960->deemph;
+}
+
+static int wm8960_put_deemph(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
+	int deemph = ucontrol->value.enumerated.item[0];
+
+	if (deemph > 1)
+		return -EINVAL;
+
+	wm8960->deemph = deemph;
+
+	return wm8960_set_deemph(codec);
+}
+
 static const DECLARE_TLV_DB_SCALE(adc_tlv, -9700, 50, 0);
 static const DECLARE_TLV_DB_SCALE(dac_tlv, -12700, 50, 1);
 static const DECLARE_TLV_DB_SCALE(bypass_tlv, -2100, 300, 0);
@@ -133,6 +188,8 @@ SOC_ENUM("ADC Polarity", wm8960_enum[0]),
 SOC_SINGLE("ADC High Pass Filter Switch", WM8960_DACCTL1, 0, 1, 0),
 
 SOC_ENUM("DAC Polarity", wm8960_enum[2]),
+SOC_SINGLE_BOOL_EXT("DAC Deemphasis Switch", 0,
+		    wm8960_get_deemph, wm8960_put_deemph),
 
 SOC_ENUM("3D Filter Upper Cut-Off", wm8960_enum[2]),
 SOC_ENUM("3D Filter Lower Cut-Off", wm8960_enum[3]),
@@ -437,6 +494,7 @@ static int wm8960_hw_params(struct snd_pcm_substream *substream,
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_device *socdev = rtd->socdev;
 	struct snd_soc_codec *codec = socdev->card->codec;
+	struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
 	u16 iface = snd_soc_read(codec, WM8960_IFACE1) & 0xfff3;
 
 	/* bit size */
@@ -451,6 +509,12 @@ static int wm8960_hw_params(struct snd_pcm_substream *substream,
 		break;
 	}
 
+	/* Update filters for the new rate */
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		wm8960->playback_fs = params_rate(params);
+		wm8960_set_deemph(codec);
+	}
+
 	/* set iface */
 	snd_soc_write(codec, WM8960_IFACE1, iface);
 	return 0;