drm: Add Allwinner A10 Display Engine support

The Allwinner A10 and subsequent SoCs share the same display pipeline, with
variations in the number of controllers (1 or 2), or the presence or not of
some output (HDMI, TV, VGA) or not.

Add a driver with a limited set of features for now, and we will hopefully
support all of them eventually

Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

1 files changed, 161 insertions, 0 deletions

diff --git a/drivers/gpu/drm/sun4i/sun4i_layer.c b/drivers/gpu/drm/sun4i/sun4i_layer.c
new file mode 100644
index 000000000000..068ab806309b
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun4i_layer.c
@@ -0,0 +1,161 @@
+/*
+ * 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_crtc.h>
+#include <drm/drm_plane_helper.h>
+#include <drm/drmP.h>
+
+#include "sun4i_backend.h"
+#include "sun4i_drv.h"
+#include "sun4i_layer.h"
+
+#define SUN4I_NUM_LAYERS	2
+
+static int sun4i_backend_layer_atomic_check(struct drm_plane *plane,
+					    struct drm_plane_state *state)
+{
+	return 0;
+}
+
+static void sun4i_backend_layer_atomic_disable(struct drm_plane *plane,
+					       struct drm_plane_state *old_state)
+{
+	struct sun4i_layer *layer = plane_to_sun4i_layer(plane);
+	struct sun4i_drv *drv = layer->drv;
+	struct sun4i_backend *backend = drv->backend;
+
+	sun4i_backend_layer_enable(backend, layer->id, false);
+}
+
+static void sun4i_backend_layer_atomic_update(struct drm_plane *plane,
+					      struct drm_plane_state *old_state)
+{
+	struct sun4i_layer *layer = plane_to_sun4i_layer(plane);
+	struct sun4i_drv *drv = layer->drv;
+	struct sun4i_backend *backend = drv->backend;
+
+	sun4i_backend_update_layer_coord(backend, layer->id, plane);
+	sun4i_backend_update_layer_formats(backend, layer->id, plane);
+	sun4i_backend_update_layer_buffer(backend, layer->id, plane);
+	sun4i_backend_layer_enable(backend, layer->id, true);
+}
+
+static struct drm_plane_helper_funcs sun4i_backend_layer_helper_funcs = {
+	.atomic_check	= sun4i_backend_layer_atomic_check,
+	.atomic_disable	= sun4i_backend_layer_atomic_disable,
+	.atomic_update	= sun4i_backend_layer_atomic_update,
+};
+
+static const struct drm_plane_funcs sun4i_backend_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 sun4i_backend_layer_formats[] = {
+	DRM_FORMAT_ARGB8888,
+	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_RGB888,
+};
+
+static struct sun4i_layer *sun4i_layer_init_one(struct drm_device *drm,
+						enum drm_plane_type type)
+{
+	struct sun4i_drv *drv = drm->dev_private;
+	struct sun4i_layer *layer;
+	int ret;
+
+	layer = devm_kzalloc(drm->dev, sizeof(*layer), GFP_KERNEL);
+	if (!layer)
+		return ERR_PTR(-ENOMEM);
+
+	ret = drm_universal_plane_init(drm, &layer->plane, BIT(0),
+				       &sun4i_backend_layer_funcs,
+				       sun4i_backend_layer_formats,
+				       ARRAY_SIZE(sun4i_backend_layer_formats),
+				       type,
+				       NULL);
+	if (ret) {
+		dev_err(drm->dev, "Couldn't initialize layer\n");
+		return ERR_PTR(ret);
+	}
+
+	drm_plane_helper_add(&layer->plane,
+			     &sun4i_backend_layer_helper_funcs);
+	layer->drv = drv;
+
+	if (type == DRM_PLANE_TYPE_PRIMARY)
+		drv->primary = &layer->plane;
+
+	return layer;
+}
+
+struct sun4i_layer **sun4i_layers_init(struct drm_device *drm)
+{
+	struct sun4i_drv *drv = drm->dev_private;
+	struct sun4i_layer **layers;
+	int i;
+
+	layers = devm_kcalloc(drm->dev, SUN4I_NUM_LAYERS, sizeof(**layers),
+			      GFP_KERNEL);
+	if (!layers)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * The hardware is a bit unusual here.
+	 *
+	 * Even though it supports 4 layers, it does the composition
+	 * in two separate steps.
+	 *
+	 * The first one is assigning a layer to one of its two
+	 * pipes. If more that 1 layer is assigned to the same pipe,
+	 * and if pixels overlaps, the pipe will take the pixel from
+	 * the layer with the highest priority.
+	 *
+	 * The second step is the actual alpha blending, that takes
+	 * the two pipes as input, and uses the eventual alpha
+	 * component to do the transparency between the two.
+	 *
+	 * This two steps scenario makes us unable to guarantee a
+	 * robust alpha blending between the 4 layers in all
+	 * situations. So we just expose two layers, one per pipe. On
+	 * SoCs that support it, sprites could fill the need for more
+	 * layers.
+	 */
+	for (i = 0; i < SUN4I_NUM_LAYERS; i++) {
+		enum drm_plane_type type = (i == 0)
+					 ? DRM_PLANE_TYPE_PRIMARY
+					 : DRM_PLANE_TYPE_OVERLAY;
+		struct sun4i_layer *layer = layers[i];
+
+		layer = sun4i_layer_init_one(drm, type);
+		if (IS_ERR(layer)) {
+			dev_err(drm->dev, "Couldn't initialize %s plane\n",
+				i ? "overlay" : "primary");
+			return ERR_CAST(layer);
+		};
+
+		DRM_DEBUG_DRIVER("Assigning %s plane to pipe %d\n",
+				 i ? "overlay" : "primary", i);
+		regmap_update_bits(drv->backend->regs, SUN4I_BACKEND_ATTCTL_REG0(i),
+				   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK,
+				   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(i));
+
+		layer->id = i;
+	};
+
+	return layers;
+}