ASoC: pcm512x: implement set_tdm_slot interface

PCM512x can accept data padded with additional BCLK cycles
but the driver currently lacks an interface to configure this.

This leads to the problem that S24_LE format in master mode
can result in non-integer clock divisors and pcm512x running
at a rather off rate.

For example 48kHz with 48fs BCLK and SCLK at 24.576MHz uses
a divisor of 10 (rounded down from 10.6666) and results in a
51.2kHz LRCLK. With 64fs BCLK a divisor of 8 is used and
LRCLK runs at exactly 48kHz.

Fix this by providing a minimal set_tdm_slot implementation
so machine drivers can optionally configure custom BCLK ratios.

Signed-off-by: Matthias Reichl <hias@horus.com>

diff --git a/sound/soc/codecs/pcm512x.c b/sound/soc/codecs/pcm512x.c
index f0f2d4f..9a6a6e3 100644 (file)
--- a/sound/soc/codecs/pcm512x.c
+++ b/sound/soc/codecs/pcm512x.c
@@ -53,6 +53,7 @@ struct pcm512x_priv {
        unsigned long overclock_pll;
        unsigned long overclock_dac;
        unsigned long overclock_dsp;
+       int lrclk_div;
 };
 
 /*
@@ -851,7 +852,10 @@ static int pcm512x_set_dividers(struct snd_soc_dai *dai,
        int fssp;
        int gpio;
 
-       lrclk_div = snd_soc_params_to_frame_size(params);
+       if (pcm512x->lrclk_div)
+               lrclk_div = pcm512x->lrclk_div;
+       else
+               lrclk_div = snd_soc_params_to_frame_size(params);
        if (lrclk_div == 0) {
                dev_err(dev, "No LRCLK?\n");
                return -EINVAL;
@@ -1319,10 +1323,32 @@ static int pcm512x_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
        return 0;
 }
 
+static int pcm512x_set_tdm_slot(struct snd_soc_dai *dai,
+       unsigned int tx_mask, unsigned int rx_mask,
+       int slots, int width)
+{
+       struct snd_soc_component *component = dai->component;
+       struct pcm512x_priv *pcm512x = snd_soc_component_get_drvdata(component);
+
+       switch (slots) {
+       case 0:
+               pcm512x->lrclk_div = 0;
+               return 0;
+       case 2:
+               if (tx_mask != 0x03 || rx_mask != 0x03)
+                       return -EINVAL;
+               pcm512x->lrclk_div = slots * width;
+               return 0;
+       default:
+               return -EINVAL;
+       }
+}
+
 static const struct snd_soc_dai_ops pcm512x_dai_ops = {
        .startup = pcm512x_dai_startup,
        .hw_params = pcm512x_hw_params,
        .set_fmt = pcm512x_set_fmt,
+       .set_tdm_slot = pcm512x_set_tdm_slot,
 };
 
 static struct snd_soc_dai_driver pcm512x_dai = {