[PATCH v3] ASoC: hdac_hdmi: support 'ELD' mixer

[Brent Lu]

Add a binary mixer 'ELD' to each HDMI PCM device so user-space can
read the ELD data of external HDMI display.

If same PCM is connected to multiple receivers, the mixer returns the
ELD data for the first one found in the port list and ignore the rest.
Thie behavior seems iffy but is aligned with the user-space interface
exposed by patch_hdmi.c. Also the pcm-to-many routing is nor really
supported by the driver now.

Signed-off-by: Brent Lu <brent.lu@xxxxxxxxx>
---
 sound/soc/codecs/hdac_hdmi.c | 138 +++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)

diff --git a/sound/soc/codecs/hdac_hdmi.c b/sound/soc/codecs/hdac_hdmi.c
index f26b77faed59..869d1547ae5d 100644
--- a/sound/soc/codecs/hdac_hdmi.c
+++ b/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;
-- 
2.17.1