ASoC: meson: gx: add gx-formatter and gx-interface

These files are the basic block which allow to shape I2S in GX devices
the same as the AXG ones: the DAI backend only controls the interface
(i.e. clocks and pins) whereas a formatter takes care of properly
formatting the data.

gx-formatter and gx-interface are strongly inspired to axg-tdm-formatter
and axg-tdm, respectively. The long term plan is to join the two platforms
to use the same formatter solution.

There is only a minor addition here compared to what has been done for
AXG and it's "gx_formatter_create()" which is required in order to let
already existing AIU code to make use of this formatter without making any
devicetree change.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://patch.msgid.link/20260610-reshape-aiu-as-axg-v2-1-cac3663a8b51@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/meson/Makefile

@@ -4,6 +4,7 @@ snd-soc-meson-aiu-y := aiu.o
 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-encoder-spdif.o
 snd-soc-meson-aiu-y += aiu-fifo.o
 snd-soc-meson-aiu-y += aiu-fifo-i2s.o

sound/soc/meson/gx-formatter.c

@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+//
+// Copyright (c) 2026 BayLibre, SAS.
+// Author: Valerio Setti <vsetti@baylibre.com>
+
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <sound/soc.h>
+
+#include "gx-formatter.h"
+
+struct gx_formatter {
+	struct list_head list;
+	struct gx_stream *stream;
+	const struct gx_formatter_driver *drv;
+	bool enabled;
+	struct regmap *map;
+};
+
+static int gx_formatter_enable(struct gx_formatter *formatter)
+{
+	int ret;
+
+	/* Do nothing if the formatter is already enabled */
+	if (formatter->enabled)
+		return 0;
+
+	/* Setup the stream parameter in the formatter */
+	if (formatter->drv->ops->prepare) {
+		ret = formatter->drv->ops->prepare(formatter->map,
+					   formatter->drv->quirks,
+					   formatter->stream);
+		if (ret)
+			return ret;
+	}
+
+	/* Finally, actually enable the formatter */
+	if (formatter->drv->ops->enable)
+		formatter->drv->ops->enable(formatter->map);
+
+	formatter->enabled = true;
+
+	return 0;
+}
+
+static void gx_formatter_disable(struct gx_formatter *formatter)
+{
+	/* Do nothing if the formatter is already disabled */
+	if (!formatter->enabled)
+		return;
+
+	if (formatter->drv->ops->disable)
+		formatter->drv->ops->disable(formatter->map);
+
+	formatter->enabled = false;
+}
+
+static int gx_formatter_attach(struct gx_formatter *formatter)
+{
+	struct gx_stream *ts = formatter->stream;
+	int ret = 0;
+
+	mutex_lock(&ts->lock);
+
+	/* Catch up if the stream is already running when we attach */
+	if (ts->ready) {
+		ret = gx_formatter_enable(formatter);
+		if (ret) {
+			pr_err("failed to enable formatter\n");
+			goto out;
+		}
+	}
+
+	list_add_tail(&formatter->list, &ts->formatter_list);
+out:
+	mutex_unlock(&ts->lock);
+	return ret;
+}
+
+static void gx_formatter_detach(struct gx_formatter *formatter)
+{
+	struct gx_stream *ts = formatter->stream;
+
+	if (!ts)
+		return;
+
+	mutex_lock(&ts->lock);
+	list_del(&formatter->list);
+	mutex_unlock(&ts->lock);
+
+	gx_formatter_disable(formatter);
+}
+
+static int gx_formatter_power_up(struct gx_formatter *formatter,
+				      struct snd_soc_dapm_widget *w)
+{
+	struct gx_stream *ts = formatter->drv->ops->get_stream(w);
+	int ret;
+
+	/*
+	 * If we don't get a stream at this stage, it would mean that the
+	 * widget is powering up but is not attached to any backend DAI.
+	 * It should not happen, ever !
+	 */
+	if (WARN_ON(!ts))
+		return -ENODEV;
+
+	formatter->stream = ts;
+	INIT_LIST_HEAD(&formatter->list);
+	ret = gx_formatter_attach(formatter);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void gx_formatter_power_down(struct gx_formatter *formatter)
+{
+	gx_formatter_detach(formatter);
+	formatter->stream = NULL;
+}
+
+int gx_formatter_event(struct snd_soc_dapm_widget *w,
+		       struct snd_kcontrol *control,
+		       int event)
+{
+	struct snd_soc_component *c;
+	struct gx_formatter *formatter;
+	int ret = 0;
+
+	c = snd_soc_dapm_to_component(w->dapm);
+
+	if (w->priv)
+		formatter = w->priv;
+	else
+		formatter = snd_soc_component_get_drvdata(c);
+
+	switch (event) {
+	case SND_SOC_DAPM_PRE_PMU:
+		ret = gx_formatter_power_up(formatter, w);
+		break;
+
+	case SND_SOC_DAPM_PRE_PMD:
+		gx_formatter_power_down(formatter);
+		break;
+
+	default:
+		dev_err(c->dev, "Unexpected event %d\n", event);
+		return -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gx_formatter_event);
+
+int gx_formatter_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct gx_formatter_driver *drv;
+	struct gx_formatter *formatter;
+	void __iomem *regs;
+
+	drv = of_device_get_match_data(dev);
+	if (!drv) {
+		dev_err(dev, "failed to match device\n");
+		return -ENODEV;
+	}
+
+	formatter = devm_kzalloc(dev, sizeof(*formatter), GFP_KERNEL);
+	if (!formatter)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, formatter);
+	formatter->drv = drv;
+
+	regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	formatter->map = devm_regmap_init_mmio(dev, regs, drv->regmap_cfg);
+	if (IS_ERR(formatter->map)) {
+		dev_err(dev, "failed to init regmap: %ld\n",
+			PTR_ERR(formatter->map));
+		return PTR_ERR(formatter->map);
+	}
+
+	return devm_snd_soc_register_component(dev, drv->component_drv,
+					       NULL, 0);
+}
+EXPORT_SYMBOL_GPL(gx_formatter_probe);
+
+int gx_formatter_create(struct device *dev,
+			struct snd_soc_dapm_widget *w,
+			const struct gx_formatter_driver *drv,
+			struct regmap *regmap)
+{
+	struct gx_formatter *formatter;
+
+	formatter = devm_kzalloc(dev, sizeof(*formatter), GFP_KERNEL);
+	if (!formatter)
+		return -ENOMEM;
+
+	formatter->drv = drv;
+	formatter->map = regmap;
+
+	w->priv = formatter;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gx_formatter_create);
+
+int gx_stream_start(struct gx_stream *ts)
+{
+	struct gx_formatter *formatter;
+	int ret = 0;
+
+	mutex_lock(&ts->lock);
+
+	/* Start all the formatters attached to the stream */
+	list_for_each_entry(formatter, &ts->formatter_list, list) {
+		ret = gx_formatter_enable(formatter);
+		if (ret) {
+			pr_err("failed to enable formatter\n");
+			goto out;
+		}
+	}
+
+	ts->ready = true;
+
+out:
+	mutex_unlock(&ts->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gx_stream_start);
+
+void gx_stream_stop(struct gx_stream *ts)
+{
+	struct gx_formatter *formatter;
+
+	mutex_lock(&ts->lock);
+	ts->ready = false;
+
+	/* Stop all the formatters attached to the stream */
+	list_for_each_entry(formatter, &ts->formatter_list, list) {
+		gx_formatter_disable(formatter);
+	}
+
+	mutex_unlock(&ts->lock);
+}
+EXPORT_SYMBOL_GPL(gx_stream_stop);
+
+struct gx_stream *gx_stream_alloc(struct gx_iface *iface)
+{
+	struct gx_stream *ts;
+
+	ts = kzalloc(sizeof(*ts), GFP_KERNEL);
+	if (ts) {
+		INIT_LIST_HEAD(&ts->formatter_list);
+		mutex_init(&ts->lock);
+		ts->iface = iface;
+	}
+
+	return ts;
+}
+EXPORT_SYMBOL_GPL(gx_stream_alloc);
+
+void gx_stream_free(struct gx_stream *ts)
+{
+	/*
+	 * If the list is not empty, it would mean that one of the formatter
+	 * widget is still powered and attached to the interface while we
+	 * are removing the TDM DAI. It should not be possible
+	 */
+	WARN_ON(!list_empty(&ts->formatter_list));
+	mutex_destroy(&ts->lock);
+	kfree(ts);
+}
+EXPORT_SYMBOL_GPL(gx_stream_free);
+
+MODULE_DESCRIPTION("Amlogic GX formatter driver");
+MODULE_AUTHOR("Valerio Setti <vsetti@baylibre.com>");
+MODULE_LICENSE("GPL");

sound/soc/meson/gx-formatter.h

@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
+/*
+ * Copyright (c) 2026 Baylibre SAS.
+ * Author: Valerio Setti <vsetti@baylibre.com>
+ */
+
+#ifndef _MESON_GX_FORMATTER_H
+#define _MESON_GX_FORMATTER_H
+
+#include "gx-interface.h"
+
+struct platform_device;
+struct regmap;
+struct snd_soc_dapm_widget;
+struct snd_kcontrol;
+
+struct gx_formatter_hw {
+	unsigned int skew_offset;
+};
+
+struct gx_formatter_ops {
+	struct gx_stream *(*get_stream)(struct snd_soc_dapm_widget *w);
+	void (*enable)(struct regmap *map);
+	void (*disable)(struct regmap *map);
+	int (*prepare)(struct regmap *map,
+		       const struct gx_formatter_hw *quirks,
+		       struct gx_stream *ts);
+};
+
+struct gx_formatter_driver {
+	const struct snd_soc_component_driver *component_drv;
+	const struct regmap_config *regmap_cfg;
+	const struct gx_formatter_ops *ops;
+	const struct gx_formatter_hw *quirks;
+};
+
+int gx_formatter_event(struct snd_soc_dapm_widget *w,
+		       struct snd_kcontrol *control,
+		       int event);
+int gx_formatter_probe(struct platform_device *pdev);
+
+int gx_formatter_create(struct device *dev,
+			struct snd_soc_dapm_widget *w,
+			const struct gx_formatter_driver *drv,
+			struct regmap *regmap);
+
+/*
+ * Formatter data is already freed when the associated device is removed,
+ * so we just need to remove the pointer from the widget.
+ */
+static inline void gx_formatter_free(struct snd_soc_dapm_widget *w)
+{
+	w->priv = NULL;
+}
+
+#endif /* _MESON_GX_FORMATTER_H */

sound/soc/meson/gx-interface.h

@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
+/*
+ * Copyright (c) 2026 Baylibre SAS.
+ * Author: Valerio Setti <vsetti@baylibre.com>
+ */
+
+#ifndef _MESON_GX_INTERFACE_H
+#define _MESON_GX_INTERFACE_H
+
+#include <linux/clk.h>
+#include <linux/regmap.h>
+#include <sound/pcm.h>
+#include <sound/soc.h>
+#include <sound/soc-dai.h>
+
+struct gx_iface {
+	struct clk *mclk;
+	unsigned long mclk_rate;
+
+	/* format is common to all the DAIs of the iface */
+	unsigned int fmt;
+
+	/* For component wide symmetry */
+	int rate;
+
+	/* Only for GX platform */
+	int bs_quirk;
+};
+
+struct gx_stream {
+	struct gx_iface *iface;
+	struct list_head formatter_list;
+	struct mutex lock;
+	unsigned int channels;
+	unsigned int width;
+	unsigned int physical_width;
+	bool ready;
+
+	/* For continuous clock tracking */
+	bool clk_enabled;
+};
+
+struct gx_stream *gx_stream_alloc(struct gx_iface *iface);
+void gx_stream_free(struct gx_stream *ts);
+int gx_stream_start(struct gx_stream *ts);
+void gx_stream_stop(struct gx_stream *ts);
+
+#endif /* _MESON_GX_INTERFACE_H */