Introduce aiu-formatter-i2s, a gx_formatter implementation for the AIU I2S
playback path. This is going to replace data formatting tasks that are
currently being implemented in aiu-encoder-i2s.

This should ideally follow the same design pattern used on the AXG
platform (see axg-tdmout), but the problem here is that all playback
features (including data formatting) so far are implemented in the AIU
component. Getting the full AXG design would mean introducing incompatible
device-tree changes. Therefore aiu-formatter-i2s is kept very simple and
it only implements the bare minimum functionalities to provide I2S
playback formatting. It's not a standalone component though because this
is still implemented by AIU.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>
---
 sound/soc/meson/Makefile            |   1 +
 sound/soc/meson/aiu-formatter-i2s.c | 106 ++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)

diff --git a/sound/soc/meson/Makefile b/sound/soc/meson/Makefile
index 146ec81526ba091a174a113ce3d8412ddbbfd9dd..f9ec0ebb01f048728b8f85fd8e58fb90df990470 100644
--- a/sound/soc/meson/Makefile
+++ b/sound/soc/meson/Makefile
@@ -5,6 +5,7 @@ snd-soc-meson-aiu-y += aiu-acodec-ctrl.o
 snd-soc-meson-aiu-y += aiu-codec-ctrl.o
 snd-soc-meson-aiu-y += aiu-encoder-i2s.o
 snd-soc-meson-aiu-y += gx-formatter.o
+snd-soc-meson-aiu-y += aiu-formatter-i2s.o
 snd-soc-meson-aiu-y += aiu-encoder-spdif.o
 snd-soc-meson-aiu-y += aiu-fifo.o
 snd-soc-meson-aiu-y += aiu-fifo-i2s.o
diff --git a/sound/soc/meson/aiu-formatter-i2s.c b/sound/soc/meson/aiu-formatter-i2s.c
new file mode 100644
index 0000000000000000000000000000000000000000..c7eff04521de3c282f7f79864143e073ff1b2f27
--- /dev/null
+++ b/sound/soc/meson/aiu-formatter-i2s.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2026 BayLibre, SAS.
+// Author: Valerio Setti <vsetti@baylibre.com>
+
+#include <sound/pcm_params.h>
+#include <sound/soc.h>
+#include <sound/soc-dai.h>
+
+#include "aiu.h"
+#include "gx-formatter.h"
+
+#define AIU_I2S_SOURCE_DESC_MODE_8CH	BIT(0)
+#define AIU_I2S_SOURCE_DESC_MODE_24BIT	BIT(5)
+#define AIU_I2S_SOURCE_DESC_MODE_32BIT	BIT(9)
+#define AIU_I2S_SOURCE_DESC_MODE_SPLIT	BIT(11)
+#define AIU_RST_SOFT_I2S_FAST		BIT(0)
+
+#define AIU_I2S_DAC_CFG_MSB_FIRST	BIT(2)
+
+static struct snd_soc_dai *
+aiu_formatter_i2s_get_be(struct snd_soc_dapm_widget *w)
+{
+	struct snd_soc_dapm_path *p;
+	struct snd_soc_dai *be;
+
+	snd_soc_dapm_widget_for_each_sink_path(w, p) {
+		if (!p->connect)
+			continue;
+
+		if (p->sink->id == snd_soc_dapm_dai_in)
+			return (struct snd_soc_dai *)p->sink->priv;
+
+		be = aiu_formatter_i2s_get_be(p->sink);
+		if (be)
+			return be;
+	}
+
+	return NULL;
+}
+
+static struct gx_stream *
+aiu_formatter_i2s_get_stream(struct snd_soc_dapm_widget *w)
+{
+	struct snd_soc_dai *be = aiu_formatter_i2s_get_be(w);
+
+	if (!be)
+		return NULL;
+
+	return snd_soc_dai_dma_data_get_playback(be);
+}
+
+static int aiu_formatter_i2s_prepare(struct regmap *map,
+				 const struct gx_formatter_hw *quirks,
+				 struct gx_stream *ts)
+{
+	/* Always operate in split (classic interleaved) mode */
+	unsigned int desc = AIU_I2S_SOURCE_DESC_MODE_SPLIT;
+	unsigned int tmp;
+
+	/* Reset required to update the pipeline */
+	regmap_write(map, AIU_RST_SOFT, AIU_RST_SOFT_I2S_FAST);
+	regmap_read(map, AIU_I2S_SYNC, &tmp);
+
+	switch (ts->physical_width) {
+	case 16: /* Nothing to do */
+		break;
+
+	case 32:
+		desc |= (AIU_I2S_SOURCE_DESC_MODE_24BIT |
+			 AIU_I2S_SOURCE_DESC_MODE_32BIT);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	switch (ts->channels) {
+	case 2: /* Nothing to do */
+		break;
+	case 8:
+		desc |= AIU_I2S_SOURCE_DESC_MODE_8CH;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap_update_bits(map, AIU_I2S_SOURCE_DESC,
+				AIU_I2S_SOURCE_DESC_MODE_8CH |
+				AIU_I2S_SOURCE_DESC_MODE_24BIT |
+				AIU_I2S_SOURCE_DESC_MODE_32BIT |
+				AIU_I2S_SOURCE_DESC_MODE_SPLIT,
+				desc);
+
+	/* Send data MSB first */
+	regmap_update_bits(map, AIU_I2S_DAC_CFG,
+				AIU_I2S_DAC_CFG_MSB_FIRST,
+				AIU_I2S_DAC_CFG_MSB_FIRST);
+
+	return 0;
+}
+
+const struct gx_formatter_ops aiu_formatter_i2s_ops = {
+	.get_stream	= aiu_formatter_i2s_get_stream,
+	.prepare	= aiu_formatter_i2s_prepare,
+};

-- 
2.39.5