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From 5fd7bb26ef791a7da1c0573b980ab4fe6b9c2641 Mon Sep 17 00:00:00 2001
From: Matthias Reichl <hias@horus.com>
Date: Thu, 22 Feb 2018 11:55:06 +0100
Subject: [PATCH] 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>
---
 sound/soc/codecs/pcm512x.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

--- 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 s
 	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_so
 	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 = {