ASoC: audio_graph_card2: Add support for variable slot widths

Some audio hardware cannot support the same slot width for all sample
widths, or a slot width equal to the sample width for all sample widths.
This is usually due either to limitations of the audio serial port or
system clocking restrictions.
A typical example would be:

- 16-bit samples in 16-bit slots
- 24-bit samples in 32-bit slots

The new dai-tdm-slot-width-map property allows setting a mapping of
sample widths and the corresponding tdm slot widths and slot counts.
Although the slot count is usually the same for all cases this does
allow for adding padding slots to maintain the same bitclk frequency.

The property is added to each endpoint node that needs the component
DAI to be told the TDM slot width and count.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220228172754.453783-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 101 insertions, 0 deletions

diff --git a/sound/soc/generic/audio-graph-card2.c b/sound/soc/generic/audio-graph-card2.c
index c3947347dda3..c0f3907a01fd 100644
--- a/sound/soc/generic/audio-graph-card2.c
+++ b/sound/soc/generic/audio-graph-card2.c
@@ -503,6 +503,10 @@ static int __graph_parse_node(struct asoc_simple_priv *priv,
 	if (ret < 0)
 		return ret;
 
+	ret = asoc_simple_parse_tdm_width_map(dev, ep, dai);
+	if (ret < 0)
+		return ret;
+
 	ret = asoc_simple_parse_clk(dev, ep, dai, dlc);
 	if (ret < 0)
 		return ret;
diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
index a4babfb63175..14c8b3a74c2d 100644
--- a/sound/soc/generic/simple-card-utils.c
+++ b/sound/soc/generic/simple-card-utils.c
@@ -12,6 +12,7 @@
 #include <linux/of_gpio.h>
 #include <linux/of_graph.h>
 #include <sound/jack.h>
+#include <sound/pcm_params.h>
 #include <sound/simple_card_utils.h>
 
 void asoc_simple_convert_fixup(struct asoc_simple_data *data,
@@ -87,6 +88,51 @@ int asoc_simple_parse_daifmt(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(asoc_simple_parse_daifmt);
 
+int asoc_simple_parse_tdm_width_map(struct device *dev, struct device_node *np,
+				    struct asoc_simple_dai *dai)
+{
+	u32 *array_values, *p;
+	int n, i, ret;
+
+	if (!of_property_read_bool(np, "dai-tdm-slot-width-map"))
+		return 0;
+
+	n = of_property_count_elems_of_size(np, "dai-tdm-slot-width-map", sizeof(u32));
+	if (n % 3) {
+		dev_err(dev, "Invalid number of cells for dai-tdm-slot-width-map\n");
+		return -EINVAL;
+	}
+
+	dai->tdm_width_map = devm_kcalloc(dev, n, sizeof(*dai->tdm_width_map), GFP_KERNEL);
+	if (!dai->tdm_width_map)
+		return -ENOMEM;
+
+	array_values = kcalloc(n, sizeof(*array_values), GFP_KERNEL);
+	if (!array_values)
+		return -ENOMEM;
+
+	ret = of_property_read_u32_array(np, "dai-tdm-slot-width-map", array_values, n);
+	if (ret < 0) {
+		dev_err(dev, "Could not read dai-tdm-slot-width-map: %d\n", ret);
+		goto out;
+	}
+
+	p = array_values;
+	for (i = 0; i < n / 3; ++i) {
+		dai->tdm_width_map[i].sample_bits = *p++;
+		dai->tdm_width_map[i].slot_width = *p++;
+		dai->tdm_width_map[i].slot_count = *p++;
+	}
+
+	dai->n_tdm_widths = i;
+	ret = 0;
+out:
+	kfree(array_values);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(asoc_simple_parse_tdm_width_map);
+
 int asoc_simple_set_dailink_name(struct device *dev,
 				 struct snd_soc_dai_link *dai_link,
 				 const char *fmt, ...)
@@ -309,6 +355,42 @@ static int asoc_simple_set_clk_rate(struct device *dev,
 	return clk_set_rate(simple_dai->clk, rate);
 }
 
+static int asoc_simple_set_tdm(struct snd_soc_dai *dai,
+				struct asoc_simple_dai *simple_dai,
+				struct snd_pcm_hw_params *params)
+{
+	int sample_bits = params_width(params);
+	int slot_width = simple_dai->slot_width;
+	int slot_count = simple_dai->slots;
+	int i, ret;
+
+	if (!simple_dai || !simple_dai->tdm_width_map)
+		return 0;
+
+	if (slot_width == 0)
+		slot_width = sample_bits;
+
+	for (i = 0; i < simple_dai->n_tdm_widths; ++i) {
+		if (simple_dai->tdm_width_map[i].sample_bits == sample_bits) {
+			slot_width = simple_dai->tdm_width_map[i].slot_width;
+			slot_count = simple_dai->tdm_width_map[i].slot_count;
+			break;
+		}
+	}
+
+	ret = snd_soc_dai_set_tdm_slot(dai,
+				       simple_dai->tx_slot_mask,
+				       simple_dai->rx_slot_mask,
+				       slot_count,
+				       slot_width);
+	if (ret && ret != -ENOTSUPP) {
+		dev_err(dai->dev, "simple-card: set_tdm_slot error: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 int asoc_simple_hw_params(struct snd_pcm_substream *substream,
 			  struct snd_pcm_hw_params *params)
 {
@@ -362,6 +444,21 @@ int asoc_simple_hw_params(struct snd_pcm_substream *substream,
 				return ret;
 		}
 	}
+
+	for_each_prop_dai_codec(props, i, pdai) {
+		sdai = asoc_rtd_to_codec(rtd, i);
+		ret = asoc_simple_set_tdm(sdai, pdai, params);
+		if (ret < 0)
+			return ret;
+	}
+
+	for_each_prop_dai_cpu(props, i, pdai) {
+		sdai = asoc_rtd_to_cpu(rtd, i);
+		ret = asoc_simple_set_tdm(sdai, pdai, params);
+		if (ret < 0)
+			return ret;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(asoc_simple_hw_params);