drm/vc4: hdmi: Add jack detection to HDMI audio driver

Add ALSA jack detection to the vc4-hdmi audio driver so userspace knows
when to add/remove HDMI audio devices.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: David Turner <david.turner@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250317-vc4_hotplug-v4-3-2af625629186@raspberrypi.com
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Author: cillian64

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -51,6 +51,7 @@
 #include <linux/reset.h>
 #include <sound/dmaengine_pcm.h>
 #include <sound/hdmi-codec.h>
+#include <sound/jack.h>
 #include <sound/pcm_drm_eld.h>
 #include <sound/pcm_params.h>
 #include <sound/soc.h>
@@ -2175,6 +2176,22 @@ static const struct drm_connector_hdmi_audio_funcs vc4_hdmi_audio_funcs = {
 	.shutdown = vc4_hdmi_audio_shutdown,
 };
 
+static int vc4_hdmi_codec_init(struct snd_soc_pcm_runtime *rtd)
+{
+	struct vc4_hdmi *vc4_hdmi = snd_soc_card_get_drvdata(rtd->card);
+	struct snd_soc_component *component = snd_soc_rtd_to_codec(rtd, 0)->component;
+	int ret;
+
+	ret = snd_soc_card_jack_new(rtd->card, "HDMI Jack", SND_JACK_LINEOUT,
+				    &vc4_hdmi->hdmi_jack);
+	if (ret) {
+		dev_err(rtd->dev, "HDMI Jack creation failed: %d\n", ret);
+		return ret;
+	}
+
+	return snd_soc_component_set_jack(component, &vc4_hdmi->hdmi_jack, NULL);
+}
+
 static int vc4_hdmi_audio_init(struct vc4_hdmi *vc4_hdmi)
 {
 	const struct vc4_hdmi_register *mai_data =
@@ -2288,6 +2305,7 @@ static int vc4_hdmi_audio_init(struct vc4_hdmi *vc4_hdmi)
 	dai_link->cpus->dai_name = dev_name(dev);
 	dai_link->codecs->name = dev_name(&vc4_hdmi->connector.hdmi_audio.codec_pdev->dev);
 	dai_link->platforms->name = dev_name(dev);
+	dai_link->init = vc4_hdmi_codec_init;
 
 	card->dai_link = dai_link;
 	card->num_links = 1;

drivers/gpu/drm/vc4/vc4_hdmi.h

@@ -4,6 +4,7 @@
 #include <drm/drm_connector.h>
 #include <media/cec.h>
 #include <sound/dmaengine_pcm.h>
+#include <sound/hdmi-codec.h>
 #include <sound/soc.h>
 
 #include "vc4_drv.h"
@@ -211,6 +212,12 @@ struct vc4_hdmi {
 	 * KMS hooks. Protected by @mutex.
 	 */
 	enum hdmi_colorspace output_format;
+
+	/**
+	 * @hdmi_jack: Represents the connection state of the HDMI plug, for
+	 * ALSA jack detection.
+	 */
+	struct snd_soc_jack hdmi_jack;
 };
 
 #define connector_to_vc4_hdmi(_connector)				\