ASoC: meson: axg-tdm: add continuous clock support

Some devices may need the clocks running, even while paused.
Add support for this use case.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20240426152946.3078805-5-jbrunet@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: jbrun3t

sound/soc/meson/axg-tdm-formatter.c

@@ -392,6 +392,46 @@ void axg_tdm_stream_free(struct axg_tdm_stream *ts)
 }
 EXPORT_SYMBOL_GPL(axg_tdm_stream_free);
 
+int axg_tdm_stream_set_cont_clocks(struct axg_tdm_stream *ts,
+				   unsigned int fmt)
+{
+	int ret = 0;
+
+	if (fmt & SND_SOC_DAIFMT_CONT) {
+		/* Clock are already enabled - skipping */
+		if (ts->clk_enabled)
+			return 0;
+
+		ret = clk_prepare_enable(ts->iface->mclk);
+		if (ret)
+			return ret;
+
+		ret = clk_prepare_enable(ts->iface->sclk);
+		if (ret)
+			goto err_sclk;
+
+		ret = clk_prepare_enable(ts->iface->lrclk);
+		if (ret)
+			goto err_lrclk;
+
+		ts->clk_enabled = true;
+		return 0;
+	}
+
+	/* Clocks are already disabled - skipping */
+	if (!ts->clk_enabled)
+		return 0;
+
+	clk_disable_unprepare(ts->iface->lrclk);
+err_lrclk:
+	clk_disable_unprepare(ts->iface->sclk);
+err_sclk:
+	clk_disable_unprepare(ts->iface->mclk);
+	ts->clk_enabled = false;
+	return ret;
+}
+EXPORT_SYMBOL_GPL(axg_tdm_stream_set_cont_clocks);
+
 MODULE_DESCRIPTION("Amlogic AXG TDM formatter driver");
 MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
 MODULE_LICENSE("GPL v2");

sound/soc/meson/axg-tdm-interface.c

@@ -309,6 +309,7 @@ static int axg_tdm_iface_hw_params(struct snd_pcm_substream *substream,
 				   struct snd_soc_dai *dai)
 {
 	struct axg_tdm_iface *iface = snd_soc_dai_get_drvdata(dai);
+	struct axg_tdm_stream *ts = snd_soc_dai_get_dma_data(dai, substream);
 	int ret;
 
 	switch (iface->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
@@ -346,7 +347,19 @@ static int axg_tdm_iface_hw_params(struct snd_pcm_substream *substream,
 			return ret;
 	}
 
-	return 0;
+	ret = axg_tdm_stream_set_cont_clocks(ts, iface->fmt);
+	if (ret)
+		dev_err(dai->dev, "failed to apply continuous clock setting\n");
+
+	return ret;
+}
+
+static int axg_tdm_iface_hw_free(struct snd_pcm_substream *substream,
+				 struct snd_soc_dai *dai)
+{
+	struct axg_tdm_stream *ts = snd_soc_dai_get_dma_data(dai, substream);
+
+	return axg_tdm_stream_set_cont_clocks(ts, 0);
 }
 
 static int axg_tdm_iface_trigger(struct snd_pcm_substream *substream,
@@ -417,6 +430,7 @@ static const struct snd_soc_dai_ops axg_tdm_iface_ops = {
 	.set_fmt	= axg_tdm_iface_set_fmt,
 	.startup	= axg_tdm_iface_startup,
 	.hw_params	= axg_tdm_iface_hw_params,
+	.hw_free	= axg_tdm_iface_hw_free,
 	.trigger	= axg_tdm_iface_trigger,
 };
 

sound/soc/meson/axg-tdm.h

@@ -58,12 +58,17 @@ struct axg_tdm_stream {
 	unsigned int physical_width;
 	u32 *mask;
 	bool ready;
+
+	/* For continuous clock tracking */
+	bool clk_enabled;
 };
 
 struct axg_tdm_stream *axg_tdm_stream_alloc(struct axg_tdm_iface *iface);
 void axg_tdm_stream_free(struct axg_tdm_stream *ts);
 int axg_tdm_stream_start(struct axg_tdm_stream *ts);
 void axg_tdm_stream_stop(struct axg_tdm_stream *ts);
+int axg_tdm_stream_set_cont_clocks(struct axg_tdm_stream *ts,
+				   unsigned int fmt);
 
 static inline int axg_tdm_stream_reset(struct axg_tdm_stream *ts)
 {