drm/bridge: dw-hdmi-i2s: add .get_eld support

Provide the eld to the generic hdmi-codec driver.
This will let the driver enforce the maximum channel number and set the
channel allocation depending on the hdmi sink.

Cc: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190812125016.20169-1-jbrunet@baylibre.com

drivers/gpu/drm/bridge/synopsys/dw-hdmi-audio.h

@@ -14,6 +14,7 @@ struct dw_hdmi_audio_data {
 
 struct dw_hdmi_i2s_audio_data {
 	struct dw_hdmi *hdmi;
+	u8 *eld;
 
 	void (*write)(struct dw_hdmi *hdmi, u8 val, int offset);
 	u8 (*read)(struct dw_hdmi *hdmi, int offset);

drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c

@@ -10,6 +10,7 @@
 #include <linux/module.h>
 
 #include <drm/bridge/dw_hdmi.h>
+#include <drm/drm_crtc.h>
 
 #include <sound/hdmi-codec.h>
 
@@ -121,6 +122,15 @@ static void dw_hdmi_i2s_audio_shutdown(struct device *dev, void *data)
 	dw_hdmi_audio_disable(hdmi);
 }
 
+static int dw_hdmi_i2s_get_eld(struct device *dev, void *data, uint8_t *buf,
+			       size_t len)
+{
+	struct dw_hdmi_i2s_audio_data *audio = data;
+
+	memcpy(buf, audio->eld, min_t(size_t, MAX_ELD_BYTES, len));
+	return 0;
+}
+
 static int dw_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
 				  struct device_node *endpoint)
 {
@@ -144,6 +154,7 @@ static int dw_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
 static struct hdmi_codec_ops dw_hdmi_i2s_ops = {
 	.hw_params	= dw_hdmi_i2s_hw_params,
 	.audio_shutdown	= dw_hdmi_i2s_audio_shutdown,
+	.get_eld	= dw_hdmi_i2s_get_eld,
 	.get_dai_id	= dw_hdmi_i2s_get_dai_id,
 };
 

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

@@ -2799,6 +2799,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
 		struct dw_hdmi_i2s_audio_data audio;
 
 		audio.hdmi	= hdmi;
+		audio.eld	= hdmi->connector.eld;
 		audio.write	= hdmi_writeb;
 		audio.read	= hdmi_readb;
 		hdmi->enable_audio = dw_hdmi_i2s_audio_enable;