Several DRM drivers implement HDMI codec support (despite its name it
applies to both HDMI and DisplayPort drivers). Implement generic
framework to be used by these drivers. This removes a requirement to
implement get_eld() callback and provides default implementation for
codec's plug handling.

The framework is integrated with the DRM HDMI Connector framework, but
can be used by DisplayPort drivers.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---
 drivers/gpu/drm/Makefile                   |   1 +
 drivers/gpu/drm/drm_connector.c            |  10 ++
 drivers/gpu/drm/drm_connector_hdmi_codec.c | 186 +++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_internal.h             |   5 +
 include/drm/drm_connector.h                |  80 +++++++++++++
 5 files changed, 282 insertions(+)

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 1677c1f335fbb0c6114bdb4cc0b12eb407d84564..afdd9268ca23ac7602e73bbe45f3f9cd090a3afd 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -42,6 +42,7 @@ drm-y := \
 	drm_cache.o \
 	drm_color_mgmt.o \
 	drm_connector.o \
+	drm_connector_hdmi_codec.o \
 	drm_crtc.o \
 	drm_displayid.o \
 	drm_drv.o \
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index fc35f47e2849ed6786d6223ac9c69e1c359fc648..1a155a9fb401f687e5a88e72faca1e81d944b6d2 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -279,6 +279,7 @@ static int __drm_connector_init(struct drm_device *dev,
 	mutex_init(&connector->mutex);
 	mutex_init(&connector->edid_override_mutex);
 	mutex_init(&connector->hdmi.infoframes.lock);
+	mutex_init(&connector->hdmi_codec.lock);
 	connector->edid_blob_ptr = NULL;
 	connector->epoch_counter = 0;
 	connector->tile_blob_ptr = NULL;
@@ -533,6 +534,12 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 
 	connector->hdmi.funcs = hdmi_funcs;
 
+	if (connector->hdmi_codec.i2s || connector->hdmi_codec.spdif) {
+		ret = drm_connector_hdmi_codec_init(connector);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(drmm_connector_hdmi_init);
@@ -631,6 +638,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
 		    DRM_CONNECTOR_REGISTERED))
 		drm_connector_unregister(connector);
 
+	drm_connector_hdmi_codec_cleanup(connector);
+
 	if (connector->privacy_screen) {
 		drm_privacy_screen_put(connector->privacy_screen);
 		connector->privacy_screen = NULL;
@@ -669,6 +678,7 @@ void drm_connector_cleanup(struct drm_connector *connector)
 		connector->funcs->atomic_destroy_state(connector,
 						       connector->state);
 
+	mutex_destroy(&connector->hdmi_codec.lock);
 	mutex_destroy(&connector->hdmi.infoframes.lock);
 	mutex_destroy(&connector->mutex);
 
diff --git a/drivers/gpu/drm/drm_connector_hdmi_codec.c b/drivers/gpu/drm/drm_connector_hdmi_codec.c
new file mode 100644
index 0000000000000000000000000000000000000000..e362852c186109644e9033eb8eaf63b864166d5a
--- /dev/null
+++ b/drivers/gpu/drm/drm_connector_hdmi_codec.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (c) 2024 Linaro Ltd
+ */
+
+#include <linux/mutex.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_connector.h>
+#include <drm/drm_device.h>
+
+#include <sound/hdmi-codec.h>
+
+#include "drm_internal.h"
+
+static int drm_connector_hdmi_codec_audio_startup(struct device *dev, void *data)
+{
+	struct drm_connector *connector = data;
+	const struct drm_connector_hdmi_codec_funcs *funcs =
+		connector->hdmi.funcs->codec_funcs;
+
+	if (funcs->audio_startup)
+		return funcs->audio_startup(connector);
+
+	return 0;
+}
+
+static int drm_connector_hdmi_codec_prepare(struct device *dev, void *data,
+					    struct hdmi_codec_daifmt *fmt,
+					    struct hdmi_codec_params *hparms)
+{
+	struct drm_connector *connector = data;
+	const struct drm_connector_hdmi_codec_funcs *funcs =
+		connector->hdmi.funcs->codec_funcs;
+
+	return funcs->prepare(connector, fmt, hparms);
+}
+
+static void drm_connector_hdmi_codec_audio_shutdown(struct device *dev, void *data)
+{
+	struct drm_connector *connector = data;
+	const struct drm_connector_hdmi_codec_funcs *funcs =
+		connector->hdmi.funcs->codec_funcs;
+
+	return funcs->audio_shutdown(connector);
+}
+
+static int drm_connector_hdmi_codec_mute_stream(struct device *dev, void *data,
+						bool enable, int direction)
+{
+	struct drm_connector *connector = data;
+	const struct drm_connector_hdmi_codec_funcs *funcs =
+		connector->hdmi.funcs->codec_funcs;
+
+	if (funcs->mute_stream)
+		return funcs->mute_stream(connector, enable, direction);
+
+	return -ENOTSUPP;
+}
+
+static int drm_connector_hdmi_codec_get_dai_id(struct snd_soc_component *comment,
+		  struct device_node *endpoint,
+		  void *data)
+{
+	struct drm_connector *connector = data;
+	struct of_endpoint of_ep;
+	int ret;
+
+	if (connector->hdmi_codec.sound_dai_port < 0)
+		return -ENOTSUPP;
+
+	ret = of_graph_parse_endpoint(endpoint, &of_ep);
+	if (ret < 0)
+		return ret;
+
+	if (of_ep.port == connector->hdmi_codec.sound_dai_port)
+		return 0;
+
+	return -EINVAL;
+}
+
+static int drm_connector_hdmi_codec_get_eld(struct device *dev, void *data,
+					    uint8_t *buf, size_t len)
+{
+	struct drm_connector *connector = data;
+
+	//  FIXME: locking against drm_edid_to_eld ?
+	memcpy(buf, connector->eld, min(sizeof(connector->eld), len));
+
+	return 0;
+}
+
+static int drm_connector_hdmi_codec_hook_plugged_cb(struct device *dev,
+						    void *data,
+						    hdmi_codec_plugged_cb fn,
+						    struct device *codec_dev)
+{
+	struct drm_connector *connector = data;
+
+	mutex_lock(&connector->hdmi_codec.lock);
+
+	connector->hdmi_codec.plugged_cb = fn;
+	connector->hdmi_codec.plugged_cb_dev = codec_dev;
+
+	fn(codec_dev, connector->hdmi_codec.last_state);
+
+	mutex_unlock(&connector->hdmi_codec.lock);
+
+	return 0;
+}
+
+void drm_connector_hdmi_codec_plugged_notify(struct drm_connector *connector,
+					     bool plugged)
+{
+	mutex_lock(&connector->hdmi_codec.lock);
+
+	connector->hdmi_codec.last_state = plugged;
+
+	if (connector->hdmi_codec.plugged_cb &&
+	    connector->hdmi_codec.plugged_cb_dev)
+		connector->hdmi_codec.plugged_cb(connector->hdmi_codec.plugged_cb_dev,
+						 connector->hdmi_codec.last_state);
+
+	mutex_unlock(&connector->hdmi_codec.lock);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_codec_plugged_notify);
+
+static const struct hdmi_codec_ops drm_connector_hdmi_codec_ops = {
+	.audio_startup = drm_connector_hdmi_codec_audio_startup,
+	.prepare = drm_connector_hdmi_codec_prepare,
+	.audio_shutdown = drm_connector_hdmi_codec_audio_shutdown,
+	.mute_stream = drm_connector_hdmi_codec_mute_stream,
+	.get_eld = drm_connector_hdmi_codec_get_eld,
+	.get_dai_id = drm_connector_hdmi_codec_get_dai_id,
+	.hook_plugged_cb = drm_connector_hdmi_codec_hook_plugged_cb,
+};
+
+/**
+ * drm_connector_hdmi_codec_cleanup - Cleanup the HDMI Codec for the connector
+ * @connector: A pointer to the connector to cleanup
+ *
+ * Cleanup the HDMI codec device created for the specified connector.
+ * Can be called even if the codec wasn't allocated.
+ */
+void drm_connector_hdmi_codec_cleanup(struct drm_connector *connector)
+{
+	platform_device_unregister(connector->hdmi_codec.codec_pdev);
+}
+
+/**
+ * drm_connector_hdmi_codec_init - Initialize HDMI Codec device for the DRM connector
+ * @connector: A pointer to the connector to allocate codec for
+ *
+ * Create a HDMI codec device to be used with the specified connector.
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int drm_connector_hdmi_codec_init(struct drm_connector *connector)
+{
+	struct hdmi_codec_pdata codec_pdata = {};
+	struct platform_device *pdev;
+
+	if (!connector->hdmi.funcs->codec_funcs->prepare ||
+	    !connector->hdmi.funcs->codec_funcs->audio_shutdown ||
+	    !connector->hdmi_codec.dev)
+		return -EINVAL;
+
+	codec_pdata.ops = &drm_connector_hdmi_codec_ops;
+	codec_pdata.i2s = connector->hdmi_codec.i2s,
+	codec_pdata.spdif = connector->hdmi_codec.spdif,
+	codec_pdata.max_i2s_channels = connector->hdmi_codec.max_i2s_channels,
+	codec_pdata.data = connector;
+
+	pdev = platform_device_register_data(connector->hdmi_codec.dev,
+					     HDMI_CODEC_DRV_NAME,
+					     PLATFORM_DEVID_AUTO,
+					     &codec_pdata, sizeof(codec_pdata));
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	connector->hdmi_codec.codec_pdev = pdev;
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index b2b6a8e49dda46f1cb3b048ef7b28356dd3aaa4e..8ed58e482fac4662b659276e8bc17690e1fdb9b7 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -280,4 +280,9 @@ void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
 				const struct drm_framebuffer *fb);
 void drm_framebuffer_debugfs_init(struct drm_device *dev);
 
+/* drm_connector_hdmi_codec.c */
+
+int drm_connector_hdmi_codec_init(struct drm_connector *connector);
+void drm_connector_hdmi_codec_cleanup(struct drm_connector *connector);
+
 #endif /* __DRM_INTERNAL_H__ */
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index e3fa43291f449d70f3b92a00985336c4f2237bc6..b89f791cfa2be86ce1c5aa124c0f071d7c8a6489 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -46,6 +46,8 @@ struct drm_property_blob;
 struct drm_printer;
 struct drm_privacy_screen;
 struct edid;
+struct hdmi_codec_daifmt;
+struct hdmi_codec_params;
 struct i2c_adapter;
 
 enum drm_connector_force {
@@ -1141,6 +1143,52 @@ struct drm_connector_state {
 	struct drm_connector_hdmi_state hdmi;
 };
 
+struct drm_connector_hdmi_codec_funcs {
+	/**
+	 * @audio_startup:
+	 *
+	 * Called when ASoC starts an audio stream setup. The
+	 * @hdmi_audio_startup is optional.
+	 *
+	 * Returns:
+	 * 0 on success, a negative error code otherwise
+	 */
+	int (*audio_startup)(struct drm_connector *connector);
+
+	/**
+	 * @prepare:
+	 * Configures HDMI-encoder for audio stream. Can be called
+	 * multiple times for each setup. Mandatory.
+	 *
+	 * Returns:
+	 * 0 on success, a negative error code otherwise
+	 */
+	int (*prepare)(struct drm_connector *connector,
+		       struct hdmi_codec_daifmt *fmt,
+		       struct hdmi_codec_params *hparms);
+	/**
+	 * @audio_shutdown:
+	 *
+	 * Shut down the audio stream. Mandatory.
+	 *
+	 * Returns:
+	 * 0 on success, a negative error code otherwise
+	 */
+	void (*audio_shutdown)(struct drm_connector *connector);
+
+	/**
+	 * @mute_stream:
+	 *
+	 * Mute/unmute HDMI audio stream. The @mute_stream callback is
+	 * optional.
+	 *
+	 * Returns:
+	 * 0 on success, a negative error code otherwise
+	 */
+	int (*mute_stream)(struct drm_connector *connector,
+			   bool enable, int direction);
+};
+
 /**
  * struct drm_connector_hdmi_funcs - drm_hdmi_connector control functions
  */
@@ -1198,6 +1246,14 @@ struct drm_connector_hdmi_funcs {
 	int (*write_infoframe)(struct drm_connector *connector,
 			       enum hdmi_infoframe_type type,
 			       const u8 *buffer, size_t len);
+
+	/**
+	 * @codec_funcs:
+	 *
+	 * Implementation of the HDMI codec functionality to be used by the DRM
+	 * HDMI Codec framework.
+	 */
+	const struct drm_connector_hdmi_codec_funcs *codec_funcs;
 };
 
 /**
@@ -1660,6 +1716,22 @@ struct drm_cmdline_mode {
 	bool tv_mode_specified;
 };
 
+struct drm_connector_hdmi_codec {
+	struct platform_device *codec_pdev;
+	struct device *dev;
+
+	struct mutex lock; /* protects last_state and plugged_cb */
+	void (*plugged_cb)(struct device *dev, bool plugged);
+	struct device *plugged_cb_dev;
+	bool last_state;
+
+	int max_i2s_channels;
+	uint i2s: 1;
+	uint spdif: 1;
+
+	int sound_dai_port;
+};
+
 /*
  * struct drm_connector_hdmi - DRM Connector HDMI-related structure
  */
@@ -2118,6 +2190,11 @@ struct drm_connector {
 	 * @hdmi: HDMI-related variable and properties.
 	 */
 	struct drm_connector_hdmi hdmi;
+
+	/**
+	 * @hdmi_codec: HDMI codec properties and non-DRM state.
+	 */
+	struct drm_connector_hdmi_codec hdmi_codec;
 };
 
 #define obj_to_connector(x) container_of(x, struct drm_connector, base)
@@ -2151,6 +2228,9 @@ void drm_connector_unregister(struct drm_connector *connector);
 int drm_connector_attach_encoder(struct drm_connector *connector,
 				      struct drm_encoder *encoder);
 
+void drm_connector_hdmi_codec_plugged_notify(struct drm_connector *connector,
+					     bool plugged);
+
 void drm_connector_cleanup(struct drm_connector *connector);
 
 static inline unsigned int drm_connector_index(const struct drm_connector *connector)

-- 
2.39.5

On Fri, 22 Nov 2024, Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index b2b6a8e49dda46f1cb3b048ef7b28356dd3aaa4e..8ed58e482fac4662b659276e8bc17690e1fdb9b7 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -280,4 +280,9 @@ void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
>  				const struct drm_framebuffer *fb);
>  void drm_framebuffer_debugfs_init(struct drm_device *dev);
>  
> +/* drm_connector_hdmi_codec.c */
> +
> +int drm_connector_hdmi_codec_init(struct drm_connector *connector);
> +void drm_connector_hdmi_codec_cleanup(struct drm_connector *connector);
> +
>  #endif /* __DRM_INTERNAL_H__ */

Better fit in drm_crtc_internal.h or drm_crtc_helper_internal.h?

Maybe we could use an internal header inside display/. Or just 1:1
drm_foo_internal.h for every drm_foo.c to keep things simple and have
fewer interdependencies.

BR,
Jani.

-- 
Jani Nikula, Intel

On Fri, Nov 22, 2024 at 01:22:53PM +0200, Jani Nikula wrote:
> On Fri, 22 Nov 2024, Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote:
> > diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> > index b2b6a8e49dda46f1cb3b048ef7b28356dd3aaa4e..8ed58e482fac4662b659276e8bc17690e1fdb9b7 100644
> > --- a/drivers/gpu/drm/drm_internal.h
> > +++ b/drivers/gpu/drm/drm_internal.h
> > @@ -280,4 +280,9 @@ void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
> >  				const struct drm_framebuffer *fb);
> >  void drm_framebuffer_debugfs_init(struct drm_device *dev);
> >  
> > +/* drm_connector_hdmi_codec.c */
> > +
> > +int drm_connector_hdmi_codec_init(struct drm_connector *connector);
> > +void drm_connector_hdmi_codec_cleanup(struct drm_connector *connector);
> > +
> >  #endif /* __DRM_INTERNAL_H__ */
> 
> Better fit in drm_crtc_internal.h or drm_crtc_helper_internal.h?
> 
> Maybe we could use an internal header inside display/. Or just 1:1
> drm_foo_internal.h for every drm_foo.c to keep things simple and have
> fewer interdependencies.

Sounds like drm_connector_hdmi_codec_internal.h. Most likely we should
also split or rename drm_crtc_*_internal.h, but that's a separate topic.

-- 
With best wishes
Dmitry