ASoC: Automatically manage WM8731 deemphasis

The deemphasis filter should be selected based on sample rate for
optimal performance.

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

1 files changed, 71 insertions, 5 deletions

diff --git a/sound/soc/codecs/wm8731.c b/sound/soc/codecs/wm8731.c
index 8003761a8e02..71122dc36826 100644
--- a/sound/soc/codecs/wm8731.c
+++ b/sound/soc/codecs/wm8731.c
@@ -46,6 +46,8 @@ struct wm8731_priv {
         u16 reg_cache[WM8731_CACHEREGNUM];
         unsigned int sysclk;
         int sysclk_type;
+        int playback_fs;
+        bool deemph;
 };
 
 
@@ -65,14 +67,73 @@ static const u16 wm8731_reg[WM8731_CACHEREGNUM] = {
 
 static const char *wm8731_input_select[] = {"Line In", "Mic"};
 
-static const char *wm8731_deemph[] = {"None", "32Khz", "44.1Khz", "48Khz"};
-
 static const struct soc_enum wm8731_insel_enum =
         SOC_ENUM_SINGLE(WM8731_APANA, 2, 2, wm8731_input_select);
 
-static const struct soc_enum wm8731_deemph_enum =
-        SOC_ENUM_SINGLE(WM8731_APDIGI, 1, 4, wm8731_deemph);
+static int wm8731_deemph[] = { 0, 32000, 44100, 48000 };
+
+static int wm8731_set_deemph(struct snd_soc_codec *codec)
+{
+        struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(codec);
+        int val, i, best;
+
+        /* If we're using deemphasis select the nearest available sample
+         * rate.
+         */
+        if (wm8731->deemph) {
+                best = 1;
+                for (i = 2; i < ARRAY_SIZE(wm8731_deemph); i++) {
+                        if (abs(wm8731_deemph[i] - wm8731->playback_fs) <
+                            abs(wm8731_deemph[best] - wm8731->playback_fs))
+                                best = i;
+                }
+
+                val = best << 1;
+        } else {
+                best = 0;
+                val = 0;
+        }
+
+        dev_dbg(codec->dev, "Set deemphasis %d (%dHz)\n",
+                best, wm8731_deemph[best]);
 
+        return snd_soc_update_bits(codec, WM8731_APDIGI, 0x6, val);
+}
+
+static int wm8731_get_deemph(struct snd_kcontrol *kcontrol,
+                             struct snd_ctl_elem_value *ucontrol)
+{
+        struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+        struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(codec);
+
+        ucontrol->value.enumerated.item[0] = wm8731->deemph;
+
+        return 0;
+}
+
+static int wm8731_put_deemph(struct snd_kcontrol *kcontrol,
+                             struct snd_ctl_elem_value *ucontrol)
+{
+        struct snd_soc_codec *codec = snd_kcontrol_chip(kcontrol);
+        struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(codec);
+        int deemph = ucontrol->value.enumerated.item[0];
+        int ret = 0;
+
+        if (deemph > 1)
+                return -EINVAL;
+
+        mutex_lock(&codec->mutex);
+        if (wm8731->deemph != deemph) {
+                wm8731->deemph = deemph;
+
+                wm8731_set_deemph(codec);
+
+                ret = 1;
+        }
+        mutex_unlock(&codec->mutex);
+
+        return ret;
+}
 
 static const DECLARE_TLV_DB_SCALE(in_tlv, -3450, 150, 0);
 static const DECLARE_TLV_DB_SCALE(sidetone_tlv, -1500, 300, 0);
@@ -99,7 +160,8 @@ SOC_SINGLE_TLV("Sidetone Playback Volume", WM8731_APANA, 6, 3, 1,
 SOC_SINGLE("ADC High Pass Filter Switch", WM8731_APDIGI, 0, 1, 1),
 SOC_SINGLE("Store DC Offset Switch", WM8731_APDIGI, 4, 1, 0),
 
-SOC_ENUM("Playback De-emphasis", wm8731_deemph_enum),
+SOC_SINGLE_BOOL_EXT("Playback Deemphasis Switch", 0,
+                    wm8731_get_deemph, wm8731_put_deemph),
 };
 
 /* Output Mixer */
@@ -243,6 +305,8 @@ static int wm8731_hw_params(struct snd_pcm_substream *substream,
         u16 srate = (coeff_div[i].sr << 2) |
                 (coeff_div[i].bosr << 1) | coeff_div[i].usb;
 
+        wm8731->playback_fs = params_rate(params);
+
         snd_soc_write(codec, WM8731_SRATE, srate);
 
         /* bit size */
@@ -257,6 +321,8 @@ static int wm8731_hw_params(struct snd_pcm_substream *substream,
                 break;
         }
 
+        wm8731_set_deemph(codec);
+
         snd_soc_write(codec, WM8731_IFACE, iface);
         return 0;
 }