drm/sun4i: Add alpha property for sun8i UI layer

DE2.0 and DE3.0 UI layers supports plane-global alpha channel.
Add alpha property to the DRM plane and connect it to the
corresponding registers in mixer.
Signed-off-by: Roman Stratiienko <r.stratiienko@gmail.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20210128113940.347013-2-r.stratiienko@gmail.com

drivers/gpu/drm/sun4i/sun8i_ui_layer.c

@@ -72,6 +72,27 @@ static void sun8i_ui_layer_enable(struct sun8i_mixer *mixer, int channel,
 	}
 }
 
+static void sun8i_ui_layer_update_alpha(struct sun8i_mixer *mixer, int channel,
+					int overlay, struct drm_plane *plane)
+{
+	u32 mask, val, ch_base;
+
+	ch_base = sun8i_channel_base(mixer, channel);
+
+	mask = SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_MASK |
+		SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MASK;
+
+	val = SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA(plane->state->alpha >> 8);
+
+	val |= (plane->state->alpha == DRM_BLEND_ALPHA_OPAQUE) ?
+		SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_PIXEL :
+		SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_COMBINED;
+
+	regmap_update_bits(mixer->engine.regs,
+			   SUN8I_MIXER_CHAN_UI_LAYER_ATTR(ch_base, overlay),
+			   mask, val);
+}
+
 static int sun8i_ui_layer_update_coord(struct sun8i_mixer *mixer, int channel,
 				       int overlay, struct drm_plane *plane,
 				       unsigned int zpos)
@@ -290,6 +311,8 @@ static void sun8i_ui_layer_atomic_update(struct drm_plane *plane,
 
 	sun8i_ui_layer_update_coord(mixer, layer->channel,
 				    layer->overlay, plane, zpos);
+	sun8i_ui_layer_update_alpha(mixer, layer->channel,
+				    layer->overlay, plane);
 	sun8i_ui_layer_update_formats(mixer, layer->channel,
 				      layer->overlay, plane);
 	sun8i_ui_layer_update_buffer(mixer, layer->channel,
@@ -367,6 +390,12 @@ struct sun8i_ui_layer *sun8i_ui_layer_init_one(struct drm_device *drm,
 
 	plane_cnt = mixer->cfg->ui_num + mixer->cfg->vi_num;
 
+	ret = drm_plane_create_alpha_property(&layer->plane);
+	if (ret) {
+		dev_err(drm->dev, "Couldn't add alpha property\n");
+		return ERR_PTR(ret);
+	}
+
 	ret = drm_plane_create_zpos_property(&layer->plane, channel,
 					     0, plane_cnt - 1);
 	if (ret) {

drivers/gpu/drm/sun4i/sun8i_ui_layer.h

@@ -40,6 +40,11 @@
 #define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_FBFMT_MASK	GENMASK(12, 8)
 #define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_FBFMT_OFFSET	8
 #define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MASK	GENMASK(31, 24)
+#define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA(x)		((x) << 24)
+
+#define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_PIXEL		((0) << 1)
+#define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_LAYER		((1) << 1)
+#define SUN8I_MIXER_CHAN_UI_LAYER_ATTR_ALPHA_MODE_COMBINED	((2) << 1)
 
 struct sun8i_mixer;