ASoC: hdmi-codec: Add iec958 controls

The IEC958 status bits can be exposed and modified by the userspace
through dedicated ALSA controls.

This patch implements those controls for the hdmi-codec driver. It
relies on a default value being setup at probe time that can later be
overridden by the control put.

The hw_params callback is then called with a buffer filled with the
proper bits for the current parameters being passed on so the underlying
driver can just reuse those bits as is.

Signed-off-by: Maxime Ripard <[e-mail]>
Acked-by: Mark Brown <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

sound/soc/codecs/hdmi-codec.c

···
 	bool busy;
 	struct snd_soc_jack *jack;
 	unsigned int jack_status;
+	u8 iec_status[5];
 };
 
 static const struct snd_soc_dapm_widget hdmi_widgets[] = {
···
 	return 0;
 }
 
+static int hdmi_codec_iec958_info(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_IEC958;
+	uinfo->count = 1;
+	return 0;
+}
+
+static int hdmi_codec_iec958_default_get(struct snd_kcontrol *kcontrol,
+					 struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct hdmi_codec_priv *hcp = snd_soc_component_get_drvdata(component);
+
+	memcpy(ucontrol->value.iec958.status, hcp->iec_status,
+	       sizeof(hcp->iec_status));
+
+	return 0;
+}
+
+static int hdmi_codec_iec958_default_put(struct snd_kcontrol *kcontrol,
+					 struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct hdmi_codec_priv *hcp = snd_soc_component_get_drvdata(component);
+
+	memcpy(hcp->iec_status, ucontrol->value.iec958.status,
+	       sizeof(hcp->iec_status));
+
+	return 0;
+}
+
+static int hdmi_codec_iec958_mask_get(struct snd_kcontrol *kcontrol,
+				      struct snd_ctl_elem_value *ucontrol)
+{
+	memset(ucontrol->value.iec958.status, 0xff,
+	       sizeof_field(struct hdmi_codec_priv, iec_status));
+
+	return 0;
+}
+
 static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 			      struct snd_soc_dai *dai)
 {
···
 		params_width(params), params_rate(params),
 		params_channels(params));
 
-	ret = snd_pcm_create_iec958_consumer_hw_params(params, hp.iec.status,
-						       sizeof(hp.iec.status));
+	memcpy(hp.iec.status, hcp->iec_status, sizeof(hp.iec.status));
+	ret = snd_pcm_fill_iec958_consumer_hw_params(params, hp.iec.status,
+						     sizeof(hp.iec.status));
 	if (ret < 0) {
 		dev_err(dai->dev, "Creating IEC958 channel status failed %d\n",
 			ret);
···
 			 SNDRV_PCM_FMTBIT_IEC958_SUBFRAME_LE)
 
 struct snd_kcontrol_new hdmi_codec_controls[] = {
+	{
+		.access = SNDRV_CTL_ELEM_ACCESS_READ,
+		.iface = SNDRV_CTL_ELEM_IFACE_PCM,
+		.name = SNDRV_CTL_NAME_IEC958("", PLAYBACK, MASK),
+		.info = hdmi_codec_iec958_info,
+		.get = hdmi_codec_iec958_mask_get,
+	},
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_PCM,
+		.name = SNDRV_CTL_NAME_IEC958("", PLAYBACK, DEFAULT),
+		.info = hdmi_codec_iec958_info,
+		.get = hdmi_codec_iec958_default_get,
+		.put = hdmi_codec_iec958_default_put,
+	},
 	{
 		.access	= (SNDRV_CTL_ELEM_ACCESS_READ |
 			   SNDRV_CTL_ELEM_ACCESS_VOLATILE),
···
 
 	hcp->hcd = *hcd;
 	mutex_init(&hcp->lock);
+
+	ret = snd_pcm_create_iec958_consumer_default(hcp->iec_status,
+						     sizeof(hcp->iec_status));
+	if (ret < 0)
+		return ret;
 
 	daidrv = devm_kcalloc(dev, dai_count, sizeof(*daidrv), GFP_KERNEL);
 	if (!daidrv)