drm/sun4i: add support for Allwinner DE2 mixers

Allwinner have a new "Display Engine 2.0" in their new SoCs, which comes
with mixers to do graphic processing and feed data to TCON, like the old
backends and frontends.

Add support for the mixer on Allwinner V3s SoC; it's the simplest one.

Currently a lot of functions are still missing -- more investigations
are needed to gain enough information for them.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

drivers/gpu/drm/sun4i/Kconfig

@@ -22,3 +22,13 @@ config DRM_SUN4I_BACKEND
 	  original Allwinner Display Engine, which has a backend to
 	  do some alpha blending and feed graphics to TCON. If M is
 	  selected the module will be called sun4i-backend.
+
+config DRM_SUN8I_MIXER
+	tristate "Support for Allwinner Display Engine 2.0 Mixer"
+	depends on DRM_SUN4I
+	default MACH_SUN8I
+	help
+	  Choose this option if you have an Allwinner SoC with the
+	  Allwinner Display Engine 2.0, which has a mixer to do some
+	  graphics mixture and feed graphics to TCON, If M is
+	  selected the module will be called sun8i-mixer.

drivers/gpu/drm/sun4i/Makefile

@@ -8,8 +8,11 @@ sun4i-tcon-y += sun4i_crtc.o
 
 sun4i-backend-y += sun4i_backend.o sun4i_layer.o
 
+sun8i-mixer-y += sun8i_mixer.o sun8i_layer.o
+
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i-drm.o sun4i-tcon.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun6i_drc.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i_tv.o
 
 obj-$(CONFIG_DRM_SUN4I_BACKEND)		+= sun4i-backend.o
+obj-$(CONFIG_DRM_SUN8I_MIXER)		+= sun8i-mixer.o

drivers/gpu/drm/sun4i/sun8i_layer.c

@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) Icenowy Zheng <icenowy@aosc.io>
+ *
+ * Based on sun4i_layer.h, which is:
+ *   Copyright (C) 2015 Free Electrons
+ *   Copyright (C) 2015 NextThing Co
+ *
+ *   Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_plane_helper.h>
+#include <drm/drmP.h>
+
+#include "sun8i_layer.h"
+#include "sun8i_mixer.h"
+
+struct sun8i_plane_desc {
+	       enum drm_plane_type     type;
+	       const uint32_t          *formats;
+	       uint32_t                nformats;
+};
+
+static void sun8i_mixer_layer_atomic_disable(struct drm_plane *plane,
+					       struct drm_plane_state *old_state)
+{
+	struct sun8i_layer *layer = plane_to_sun8i_layer(plane);
+	struct sun8i_mixer *mixer = layer->mixer;
+
+	sun8i_mixer_layer_enable(mixer, layer->id, false);
+}
+
+static void sun8i_mixer_layer_atomic_update(struct drm_plane *plane,
+					      struct drm_plane_state *old_state)
+{
+	struct sun8i_layer *layer = plane_to_sun8i_layer(plane);
+	struct sun8i_mixer *mixer = layer->mixer;
+
+	sun8i_mixer_update_layer_coord(mixer, layer->id, plane);
+	sun8i_mixer_update_layer_formats(mixer, layer->id, plane);
+	sun8i_mixer_update_layer_buffer(mixer, layer->id, plane);
+	sun8i_mixer_layer_enable(mixer, layer->id, true);
+}
+
+static struct drm_plane_helper_funcs sun8i_mixer_layer_helper_funcs = {
+	.atomic_disable	= sun8i_mixer_layer_atomic_disable,
+	.atomic_update	= sun8i_mixer_layer_atomic_update,
+};
+
+static const struct drm_plane_funcs sun8i_mixer_layer_funcs = {
+	.atomic_destroy_state	= drm_atomic_helper_plane_destroy_state,
+	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
+	.destroy		= drm_plane_cleanup,
+	.disable_plane		= drm_atomic_helper_disable_plane,
+	.reset			= drm_atomic_helper_plane_reset,
+	.update_plane		= drm_atomic_helper_update_plane,
+};
+
+static const uint32_t sun8i_mixer_layer_formats[] = {
+	DRM_FORMAT_RGB888,
+	DRM_FORMAT_ARGB8888,
+	DRM_FORMAT_XRGB8888,
+};
+
+static const struct sun8i_plane_desc sun8i_mixer_planes[] = {
+	{
+		.type = DRM_PLANE_TYPE_PRIMARY,
+		.formats = sun8i_mixer_layer_formats,
+		.nformats = ARRAY_SIZE(sun8i_mixer_layer_formats),
+	},
+};
+
+static struct sun8i_layer *sun8i_layer_init_one(struct drm_device *drm,
+						struct sun8i_mixer *mixer,
+						const struct sun8i_plane_desc *plane)
+{
+	struct sun8i_layer *layer;
+	int ret;
+
+	layer = devm_kzalloc(drm->dev, sizeof(*layer), GFP_KERNEL);
+	if (!layer)
+		return ERR_PTR(-ENOMEM);
+
+	/* possible crtcs are set later */
+	ret = drm_universal_plane_init(drm, &layer->plane, 0,
+				       &sun8i_mixer_layer_funcs,
+				       plane->formats, plane->nformats,
+				       plane->type, NULL);
+	if (ret) {
+		dev_err(drm->dev, "Couldn't initialize layer\n");
+		return ERR_PTR(ret);
+	}
+
+	drm_plane_helper_add(&layer->plane,
+			     &sun8i_mixer_layer_helper_funcs);
+	layer->mixer = mixer;
+
+	return layer;
+}
+
+struct drm_plane **sun8i_layers_init(struct drm_device *drm,
+				     struct sunxi_engine *engine)
+{
+	struct drm_plane **planes;
+	struct sun8i_mixer *mixer = engine_to_sun8i_mixer(engine);
+	int i;
+
+	planes = devm_kcalloc(drm->dev, ARRAY_SIZE(sun8i_mixer_planes) + 1,
+			      sizeof(*planes), GFP_KERNEL);
+	if (!planes)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < ARRAY_SIZE(sun8i_mixer_planes); i++) {
+		const struct sun8i_plane_desc *plane = &sun8i_mixer_planes[i];
+		struct sun8i_layer *layer;
+
+		layer = sun8i_layer_init_one(drm, mixer, plane);
+		if (IS_ERR(layer)) {
+			dev_err(drm->dev, "Couldn't initialize %s plane\n",
+				i ? "overlay" : "primary");
+			return ERR_CAST(layer);
+		};
+
+		layer->id = i;
+		planes[i] = &layer->plane;
+	};
+
+	return planes;
+}

drivers/gpu/drm/sun4i/sun8i_layer.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) Icenowy Zheng <icenowy@aosc.io>
+ *
+ * Based on sun4i_layer.h, which is:
+ *   Copyright (C) 2015 Free Electrons
+ *   Copyright (C) 2015 NextThing Co
+ *
+ *   Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#ifndef _SUN8I_LAYER_H_
+#define _SUN8I_LAYER_H_
+
+struct sunxi_engine;
+
+struct sun8i_layer {
+	struct drm_plane	plane;
+	struct sun4i_drv	*drv;
+	struct sun8i_mixer	*mixer;
+	int			id;
+};
+
+static inline struct sun8i_layer *
+plane_to_sun8i_layer(struct drm_plane *plane)
+{
+	return container_of(plane, struct sun8i_layer, plane);
+}
+
+struct drm_plane **sun8i_layers_init(struct drm_device *drm,
+				     struct sunxi_engine *engine);
+#endif /* _SUN8I_LAYER_H_ */