ASoC: hdac_hdmi: support 'ELD' mixer

Add an binary mixer 'ELD' to each HDMI PCM device so user space
could read the ELD data of external HDMI display.
Signed-off-by: Brent Lu <brent.lu@intel.com>
Link: https://lore.kernel.org/r/20200818004413.12852-1-brent.lu@intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/hdac_hdmi.c

@@ -9,6 +9,7 @@
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
+
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/module.h>
@@ -107,6 +108,7 @@ struct hdac_hdmi_pcm {
 	unsigned char chmap[8]; /* ALSA API channel-map */
 	struct mutex lock;
 	int jack_event;
+	struct snd_kcontrol *eld_ctl;
 };
 
 struct hdac_hdmi_dai_port_map {
@@ -1248,6 +1250,7 @@ static void hdac_hdmi_present_sense(struct hdac_hdmi_pin *pin,
 	struct hdac_hdmi_pcm *pcm;
 	int size = 0;
 	int port_id = -1;
+	bool eld_valid, eld_changed;
 
 	if (!hdmi)
 		return;
@@ -1273,6 +1276,8 @@ static void hdac_hdmi_present_sense(struct hdac_hdmi_pin *pin,
 			size = -EINVAL;
 	}
 
+	eld_valid = port->eld.eld_valid;
+
 	if (size > 0) {
 		port->eld.eld_valid = true;
 		port->eld.eld_size = size;
@@ -1281,6 +1286,8 @@ static void hdac_hdmi_present_sense(struct hdac_hdmi_pin *pin,
 		port->eld.eld_size = 0;
 	}
 
+	eld_changed = (eld_valid != port->eld.eld_valid);
+
 	pcm = hdac_hdmi_get_pcm(hdev, port);
 
 	if (!port->eld.monitor_present || !port->eld.eld_valid) {
@@ -1313,6 +1320,12 @@ static void hdac_hdmi_present_sense(struct hdac_hdmi_pin *pin,
 
 	}
 	mutex_unlock(&hdmi->pin_mutex);
+
+	if (eld_changed && pcm)
+		snd_ctl_notify(hdmi->card,
+			       SNDRV_CTL_EVENT_MASK_VALUE |
+			       SNDRV_CTL_EVENT_MASK_INFO,
+			       &pcm->eld_ctl->id);
 }
 
 static int hdac_hdmi_add_ports(struct hdac_device *hdev,
@@ -1411,6 +1424,122 @@ static void hdac_hdmi_skl_enable_dp12(struct hdac_device *hdev)
 
 }
 
+static int hdac_hdmi_eld_ctl_info(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_info *uinfo)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct hdac_hdmi_priv *hdmi = snd_soc_component_get_drvdata(component);
+	struct hdac_hdmi_pcm *pcm;
+	struct hdac_hdmi_port *port;
+	struct hdac_hdmi_eld *eld;
+
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
+	uinfo->count = 0;
+
+	pcm = get_hdmi_pcm_from_id(hdmi, kcontrol->id.device);
+	if (!pcm) {
+		dev_dbg(component->dev, "%s: no pcm, device %d\n", __func__,
+			kcontrol->id.device);
+		return 0;
+	}
+
+	if (list_empty(&pcm->port_list)) {
+		dev_dbg(component->dev, "%s: empty port list, device %d\n",
+			__func__, kcontrol->id.device);
+		return 0;
+	}
+
+	mutex_lock(&hdmi->pin_mutex);
+
+	list_for_each_entry(port, &pcm->port_list, head) {
+		eld = &port->eld;
+
+		if (eld->eld_valid) {
+			uinfo->count = eld->eld_size;
+			break;
+		}
+	}
+
+	mutex_unlock(&hdmi->pin_mutex);
+
+	return 0;
+}
+
+static int hdac_hdmi_eld_ctl_get(struct snd_kcontrol *kcontrol,
+			    struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *component = snd_kcontrol_chip(kcontrol);
+	struct hdac_hdmi_priv *hdmi = snd_soc_component_get_drvdata(component);
+	struct hdac_hdmi_pcm *pcm;
+	struct hdac_hdmi_port *port;
+	struct hdac_hdmi_eld *eld;
+
+	memset(ucontrol->value.bytes.data, 0, ARRAY_SIZE(ucontrol->value.bytes.data));
+
+	pcm = get_hdmi_pcm_from_id(hdmi, kcontrol->id.device);
+	if (!pcm) {
+		dev_dbg(component->dev, "%s: no pcm, device %d\n", __func__,
+			kcontrol->id.device);
+		return 0;
+	}
+
+	if (list_empty(&pcm->port_list)) {
+		dev_dbg(component->dev, "%s: empty port list, device %d\n",
+			__func__, kcontrol->id.device);
+		return 0;
+	}
+
+	mutex_lock(&hdmi->pin_mutex);
+
+	list_for_each_entry(port, &pcm->port_list, head) {
+		eld = &port->eld;
+
+		if (!eld->eld_valid)
+			continue;
+
+		if (eld->eld_size > ARRAY_SIZE(ucontrol->value.bytes.data) ||
+		    eld->eld_size > ELD_MAX_SIZE) {
+			mutex_unlock(&hdmi->pin_mutex);
+
+			dev_err(component->dev, "%s: buffer too small, device %d eld_size %d\n",
+				__func__, kcontrol->id.device, eld->eld_size);
+			snd_BUG();
+			return -EINVAL;
+		}
+
+		memcpy(ucontrol->value.bytes.data, eld->eld_buffer,
+		       eld->eld_size);
+		break;
+	}
+
+	mutex_unlock(&hdmi->pin_mutex);
+
+	return 0;
+}
+
+static int hdac_hdmi_create_eld_ctl(struct snd_soc_component *component, struct hdac_hdmi_pcm *pcm)
+{
+	struct snd_kcontrol *kctl;
+	struct snd_kcontrol_new hdmi_eld_ctl = {
+		.access	= SNDRV_CTL_ELEM_ACCESS_READ |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.iface	= SNDRV_CTL_ELEM_IFACE_PCM,
+		.name	= "ELD",
+		.info	= hdac_hdmi_eld_ctl_info,
+		.get	= hdac_hdmi_eld_ctl_get,
+		.device	= pcm->pcm_id,
+	};
+
+	/* add ELD ctl with the device number corresponding to the PCM stream */
+	kctl = snd_ctl_new1(&hdmi_eld_ctl, component);
+	if (!kctl)
+		return -ENOMEM;
+
+	pcm->eld_ctl = kctl;
+
+	return snd_ctl_add(component->card->snd_card, kctl);
+}
+
 static const struct snd_soc_dai_ops hdmi_dai_ops = {
 	.startup = hdac_hdmi_pcm_open,
 	.shutdown = hdac_hdmi_pcm_close,
@@ -1784,6 +1913,15 @@ int hdac_hdmi_jack_init(struct snd_soc_dai *dai, int device,
 		}
 	}
 
+	/* add control for ELD Bytes */
+	err = hdac_hdmi_create_eld_ctl(component, pcm);
+	if (err < 0) {
+		dev_err(&hdev->dev,
+			"eld control add failed with err: %d for pcm: %d\n",
+			err, device);
+		return err;
+	}
+
 	list_add_tail(&pcm->head, &hdmi->pcm_list);
 
 	return 0;