[PATH 1/4] drm: Add Virtual DRM device driver

[Tomohito Esaki]

Virtual DRM splits the resources of an overlay plane into multiple
virtual devices to allow each plane to be accessed by each process.

This makes it possible to overlay images output from multiple processes
on a display. For example, one process displays the camera image without
compositor while another process overlays the compositor's drawing of
the UI.

The virtual DRM creates standalone virtual device and make DRM planes
from a master device (e.g. card0) accessible via one or more virtual
devices. However, these plane are no longer accessible from the original
device.
Each virtual device (and plane) can be accessed via a separate
device file.

Signed-off-by: Tomohito Esaki <etom@xxxxxxxxxx>
---
 drivers/gpu/drm/Kconfig         |   7 +
 drivers/gpu/drm/Makefile        |   1 +
 drivers/gpu/drm/vdrm/vdrm_api.h |  68 +++
 drivers/gpu/drm/vdrm/vdrm_drv.c | 859 ++++++++++++++++++++++++++++++++
 drivers/gpu/drm/vdrm/vdrm_drv.h |  80 +++
 5 files changed, 1015 insertions(+)
 create mode 100644 drivers/gpu/drm/vdrm/vdrm_api.h
 create mode 100644 drivers/gpu/drm/vdrm/vdrm_drv.c
 create mode 100644 drivers/gpu/drm/vdrm/vdrm_drv.h

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 3c16bd1afd87..ba7f4eeab385 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -294,6 +294,13 @@ config DRM_VKMS
 
 	  If M is selected the module will be called vkms.
 
+config DRM_VDRM
+	tristate "Virtual DRM"
+	depends on DRM
+	help
+	  Virtual DRM splits the resources of an overlay plane into multiple
+	  virtual devices to allow each plane to be accessed by each process.
+
 source "drivers/gpu/drm/exynos/Kconfig"
 
 source "drivers/gpu/drm/rockchip/Kconfig"
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 5279db4392df..55dbf85e2579 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -82,6 +82,7 @@ obj-$(CONFIG_DRM_VMWGFX)+= vmwgfx/
 obj-$(CONFIG_DRM_VIA)	+=via/
 obj-$(CONFIG_DRM_VGEM)	+= vgem/
 obj-$(CONFIG_DRM_VKMS)	+= vkms/
+obj-$(CONFIG_DRM_VDRM)	+= vdrm/
 obj-$(CONFIG_DRM_NOUVEAU) +=nouveau/
 obj-$(CONFIG_DRM_EXYNOS) +=exynos/
 obj-$(CONFIG_DRM_ROCKCHIP) +=rockchip/
diff --git a/drivers/gpu/drm/vdrm/vdrm_api.h b/drivers/gpu/drm/vdrm/vdrm_api.h
new file mode 100644
index 000000000000..dd4d7e774800
--- /dev/null
+++ b/drivers/gpu/drm/vdrm/vdrm_api.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * vdrm_api.h -- Virtual DRM API
+ *
+ * Copyright (C) 2021 Renesas Electronics Corporation
+ */
+
+#ifndef __VDRM_API__
+#define __VDRM_API__
+
+#include <linux/of_device.h>
+#include <drm/drm_crtc.h>
+
+/**
+ * struct vdrm_property_info - Information about the properties passed from
+ *			       the DRM driver to vDRM
+ * @prop: Parent property to pass to vDRM
+ * @default_val: Default value for the property passed to vDRM
+ */
+struct vdrm_property_info {
+	struct drm_property *prop;
+	uint64_t default_val;
+};
+
+/**
+ * struct vdrm_funcs - Callbacks to parent DRM driver
+ */
+struct vdrm_funcs {
+	/**
+	 * @dumb_create:
+	 *
+	 * Called by &drm_driver.dumb_create. Please read the documentation
+	 * for the &drm_driver.dumb_create hook for more details.
+	 */
+	int (*dumb_create)(struct drm_file *file, struct drm_device *dev,
+			   struct drm_mode_create_dumb *args);
+
+	/**
+	 * @crtc_flush:
+	 *
+	 * Called by &drm_crtc_helper_funcs.atomic_flush. Please read the
+	 * documentation for the &drm_crtc_helper_funcs.atomic_flush hook for
+	 * more details.
+	 */
+	void (*crtc_flush)(struct drm_crtc *crtc);
+};
+
+struct vdrm_device;
+struct vdrm_display;
+
+void vdrm_drv_handle_vblank(struct vdrm_display *vdisplay);
+void vdrm_drv_finish_page_flip(struct vdrm_display *vdisplay);
+struct vdrm_device *vdrm_drv_init(struct drm_device *dev,
+				  struct device_node *np, int num_props,
+				  struct vdrm_property_info *props,
+				  const struct vdrm_funcs *funcs);
+int vdrm_drv_plane_init(struct vdrm_device *vdrm, struct drm_plane *plane,
+			const struct drm_plane_funcs *funcs,
+			const struct drm_plane_helper_funcs *helper_funcs,
+			const u32 *formats, unsigned int num_formats,
+			int max_zpos);
+struct vdrm_display *vdrm_drv_display_init(struct vdrm_device *vdrm,
+					   struct drm_crtc *crtc,
+					   struct drm_plane *plane);
+int vdrm_drv_register(struct vdrm_device *vdrm);
+void vdrm_drv_fini(struct vdrm_device *vdrm);
+
+#endif /* __VDRM_API__ */
diff --git a/drivers/gpu/drm/vdrm/vdrm_drv.c b/drivers/gpu/drm/vdrm/vdrm_drv.c
new file mode 100644
index 000000000000..835bdecfc8e6
--- /dev/null
+++ b/drivers/gpu/drm/vdrm/vdrm_drv.c
@@ -0,0 +1,859 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * vdrm_drv.c -- Virtual DRM driver
+ *
+ * Copyright (C) 2021 Renesas Electronics Corporation
+ *
+ * This driver is based on drivers/gpu/drm/drm_simple_kms_helper.c.
+ */
+
+#include <linux/of_device.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_atomic_uapi.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_plane_helper.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <video/videomode.h>
+
+#include "vdrm_drv.h"
+
+static inline struct vdrm_display *
+to_vdrm_display(struct drm_connector *connector)
+{
+	return container_of(connector, struct vdrm_display, connector);
+}
+
+static inline struct vdrm_display *
+crtc_to_vdrm_display(struct drm_crtc *crtc)
+{
+	return container_of(crtc, struct vdrm_display, crtc);
+}
+
+static int vdrm_dumb_create(struct drm_file *file, struct drm_device *dev,
+			    struct drm_mode_create_dumb *args)
+{
+	struct vdrm_device *vdrm = to_vdrm_device(dev);
+
+	return vdrm->funcs->dumb_create(file, dev, args);
+}
+
+struct vdrm_framebuffer {
+	struct drm_framebuffer fb;
+	struct drm_framebuffer *parent_fb;
+};
+
+static inline struct vdrm_framebuffer *
+to_vdrm_framebuffer(struct drm_framebuffer *fb)
+{
+	return container_of(fb, struct vdrm_framebuffer, fb);
+}
+
+static void vdrm_fb_destroy(struct drm_framebuffer *fb)
+{
+	struct vdrm_framebuffer *vfb = to_vdrm_framebuffer(fb);
+
+	vfb->parent_fb->funcs->destroy(vfb->parent_fb);
+	drm_framebuffer_cleanup(fb);
+	kfree(vfb);
+}
+
+static const struct drm_framebuffer_funcs vdrm_fb_funcs = {
+	.destroy = vdrm_fb_destroy,
+};
+
+static int vdrm_fb_init(struct drm_device *dev, struct vdrm_framebuffer *vfb)
+{
+	vfb->fb = *vfb->parent_fb;
+	vfb->fb.dev = dev;
+
+	return drm_framebuffer_init(dev, &vfb->fb, &vdrm_fb_funcs);
+}
+
+static struct drm_framebuffer *
+vdrm_fb_create(struct drm_device *dev, struct drm_file *file_priv,
+	       const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+	struct vdrm_device *vdrm = to_vdrm_device(dev);
+	const struct drm_mode_config_funcs *mode_config_funcs =
+		vdrm->parent->mode_config.funcs;
+	struct vdrm_framebuffer *vfb;
+	struct drm_framebuffer *fb;
+	int ret;
+
+	vfb = kzalloc(sizeof(*vfb), GFP_KERNEL);
+	if (!vfb)
+		return ERR_PTR(-ENOMEM);
+
+	fb = mode_config_funcs->fb_create(vdrm->parent, file_priv, mode_cmd);
+	if (IS_ERR(fb)) {
+		kfree(vfb);
+		return fb;
+	}
+
+	vfb->parent_fb = fb;
+	ret = vdrm_fb_init(dev, vfb);
+	if (ret) {
+		fb->funcs->destroy(fb);
+		kfree(vfb);
+		return ERR_PTR(ret);
+	}
+
+	return &vfb->fb;
+}
+
+static const struct drm_mode_config_funcs vdrm_mode_config_funcs = {
+	.fb_create = vdrm_fb_create,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static struct drm_display_mode *vdrm_create_mode(struct vdrm_display *disp)
+{
+	struct drm_display_mode *mode;
+	struct videomode videomode;
+
+	mode = drm_mode_create(&disp->dev->ddev);
+	if (!mode)
+		return NULL;
+
+	memset(&videomode, 0, sizeof(videomode));
+	videomode.hactive = disp->plane_info.width;
+	videomode.vactive = disp->plane_info.height;
+	videomode.pixelclock =
+		disp->parent_crtc->state->adjusted_mode.crtc_clock * 1000;
+	mode->type = DRM_MODE_TYPE_PREFERRED | DRM_MODE_TYPE_DRIVER;
+	drm_display_mode_from_videomode(&videomode, mode);
+
+	return mode;
+}
+
+static int vdrm_connector_get_mode(struct drm_connector *connector)
+{
+	struct vdrm_display *disp = to_vdrm_display(connector);
+	struct drm_display_mode *mode = vdrm_create_mode(disp);
+
+	if (!mode)
+		return 0;
+
+	drm_mode_probed_add(connector, mode);
+	return 1;
+}
+
+static const struct drm_connector_helper_funcs vdrm_conn_helper_funcs = {
+	.get_modes = vdrm_connector_get_mode,
+};
+
+/*
+ * TODO:
+ *  At the time this callback is called, the parent CRTC must be connected.
+ *  Since this callback will not be called when detect() callback of the
+ *  parent connector is called, vDRM driver desn't support hotplug.
+ *  In the future, it is necessary that hotplug is supported.
+ */
+static enum drm_connector_status
+vdrm_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct vdrm_display *disp = to_vdrm_display(connector);
+	struct vdrm_device *vdrm = to_vdrm_device(connector->dev);
+	struct drm_connector *conn;
+	struct drm_connector_list_iter conn_iter;
+
+	drm_connector_list_iter_begin(vdrm->parent, &conn_iter);
+	drm_for_each_connector_iter(conn, &conn_iter) {
+		if (!conn->state)
+			continue;
+
+		if (conn->state->crtc == disp->parent_crtc) {
+			drm_connector_list_iter_end(&conn_iter);
+			return connector_status_connected;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+	return connector_status_disconnected;
+}
+
+static const struct drm_connector_funcs vdrm_conn_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.detect = vdrm_connector_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static void vdrm_drv_finish_page_flip_internal(struct vdrm_display *disp)
+{
+	struct drm_device *dev = &disp->dev->ddev;
+	struct drm_pending_vblank_event *event;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	event = disp->event;
+	disp->event = NULL;
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+
+	if (event == NULL)
+		return;
+
+	spin_lock_irqsave(&dev->event_lock, flags);
+	drm_crtc_send_vblank_event(&disp->crtc, event);
+	spin_unlock_irqrestore(&dev->event_lock, flags);
+
+	if (disp->vblank_count) {
+		drm_crtc_vblank_put(&disp->crtc);
+		disp->vblank_count--;
+	}
+}
+
+static void vdrm_plane_update(struct drm_plane *plane,
+			      struct drm_atomic_state *state)
+{
+	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state, plane);
+	struct drm_plane_state *new_state = drm_atomic_get_new_plane_state(state, plane);
+	struct drm_crtc *vcrtc_old_state = old_state->crtc;
+	struct drm_crtc *vcrtc_plane_state = new_state->crtc;
+	struct drm_crtc *crtc;
+	struct vdrm_display *vdisplay;
+
+	crtc = (old_state->crtc ? old_state->crtc : new_state->crtc);
+	if (WARN_ON(!crtc))
+		return;
+
+	vdisplay = crtc_to_vdrm_display(crtc);
+
+	old_state->crtc = vdisplay->parent_crtc;
+	new_state->crtc = vdisplay->parent_crtc;
+
+	new_state->dst.x1 += vdisplay->plane_info.x;
+	new_state->dst.y1 += vdisplay->plane_info.y;
+	vdisplay->parent_plane_helper_funcs->atomic_update(plane, state);
+
+	old_state->crtc = vcrtc_old_state;
+	new_state->crtc = vcrtc_plane_state;
+}
+
+static struct vdrm_display *
+vdrm_plane_find_display(struct vdrm_device *vdrm, struct drm_plane *plane)
+{
+	struct vdrm_display *disp;
+
+	list_for_each_entry(disp, &vdrm->disps, head) {
+		if (disp->plane == plane)
+			return disp;
+	}
+
+	return NULL;
+}
+
+static void vdrm_plane_reset(struct drm_plane *plane)
+{
+	struct vdrm_device *vdrm = to_vdrm_device(plane->dev);
+	struct vdrm_display *disp;
+
+	disp = vdrm_plane_find_display(vdrm, plane);
+	if (WARN_ON(!disp))
+		return;
+
+	disp->parent_plane_funcs->reset(plane);
+	plane->state->zpos = disp->plane_info.z;
+}
+
+static struct drm_property *
+vdrm_find_parent_property(struct vdrm_device *vdrm, struct drm_property *prop)
+{
+	int i;
+
+	for (i = 0; i < vdrm->num_props; i++) {
+		if (vdrm->props[i].prop == prop)
+			return vdrm->props[i].parent_prop;
+	}
+
+	return NULL;
+}
+
+static int vdrm_plane_set_property(struct drm_plane *plane,
+				   struct drm_plane_state *state,
+				   struct drm_property *property,
+				   uint64_t val)
+{
+	struct vdrm_device *vdrm = to_vdrm_device(plane->dev);
+	struct vdrm_display *disp;
+	struct drm_property *parent_prop;
+
+	disp = vdrm_plane_find_display(vdrm, plane);
+	if (WARN_ON(!disp))
+		return -EINVAL;
+
+	parent_prop = vdrm_find_parent_property(vdrm, property);
+	if (parent_prop && disp->parent_plane_funcs->atomic_set_property)
+		return disp->parent_plane_funcs->atomic_set_property(plane,
+								state,
+								parent_prop,
+								val);
+
+	if (vdrm->plane_props.offset_x == property) {
+		if (val > disp->parent_crtc->mode.hdisplay)
+			return -EINVAL;
+		disp->plane_info.x = val;
+	} else if (vdrm->plane_props.offset_y == property) {
+		if (val > disp->parent_crtc->mode.vdisplay)
+			return -EINVAL;
+		disp->plane_info.y = val;
+	} else if (vdrm->plane_props.width == property) {
+		if (val > disp->parent_crtc->mode.hdisplay)
+			return -EINVAL;
+		disp->plane_info.width = val;
+	} else if (vdrm->plane_props.height == property) {
+		if (val > disp->parent_crtc->mode.vdisplay)
+			return -EINVAL;
+		disp->plane_info.height = val;
+	} else {
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int vdrm_plane_get_property(struct drm_plane *plane,
+				   const struct drm_plane_state *state,
+				   struct drm_property *property,
+				   uint64_t *val)
+{
+	struct vdrm_device *vdrm = to_vdrm_device(plane->dev);
+	struct vdrm_display *disp;
+	struct drm_property *parent_prop;
+
+	disp = vdrm_plane_find_display(vdrm, plane);
+	if (WARN_ON(!disp))
+		return -EINVAL;
+
+	parent_prop = vdrm_find_parent_property(vdrm, property);
+	if (parent_prop && disp->parent_plane_funcs->atomic_get_property)
+		return disp->parent_plane_funcs->atomic_get_property(plane,
+								state,
+								parent_prop,
+								val);
+
+	if (vdrm->plane_props.offset_x == property)
+		*val = disp->plane_info.x;
+	else if (vdrm->plane_props.offset_y == property)
+		*val = disp->plane_info.y;
+	else if (vdrm->plane_props.width == property)
+		*val = disp->plane_info.width;
+	else if (vdrm->plane_props.height == property)
+		*val = disp->plane_info.height;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int vdrm_crtc_check(struct drm_crtc *crtc,
+			   struct drm_atomic_state *state)
+{
+	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state,
+									  crtc);
+	bool has_primary = crtc_state->plane_mask &
+				drm_plane_mask(crtc->primary);
+
+	/* We always want to have an active plane with an active CRTC */
+	if (has_primary != crtc_state->enable)
+		return -EINVAL;
+
+	return drm_atomic_add_affected_planes(state, crtc);
+}
+
+static void vdrm_crtc_flush(struct drm_crtc *crtc,
+			    struct drm_atomic_state *state)
+{
+	struct vdrm_display *disp = crtc_to_vdrm_display(crtc);
+	struct vdrm_device *vdrm = disp->dev;
+
+	if (crtc->state->event) {
+		struct drm_device *dev = crtc->dev;
+		unsigned long flags;
+
+		if (disp->crtc_enabled) {
+			WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+			disp->vblank_count++;
+		}
+
+		spin_lock_irqsave(&dev->event_lock, flags);
+		disp->event = crtc->state->event;
+		crtc->state->event = NULL;
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	}
+
+	if (vdrm->funcs->crtc_flush)
+		vdrm->funcs->crtc_flush(disp->parent_crtc);
+}
+
+static void vdrm_crtc_enable(struct drm_crtc *crtc,
+			     struct drm_atomic_state *state)
+{
+	struct vdrm_display *disp = crtc_to_vdrm_display(crtc);
+
+	drm_crtc_vblank_on(crtc);
+	disp->crtc_enabled = true;
+}
+
+static void vdrm_crtc_disable(struct drm_crtc *crtc,
+			      struct drm_atomic_state *state)
+{
+	struct vdrm_display *disp = crtc_to_vdrm_display(crtc);
+	unsigned long flags;
+	bool pending;
+
+	disp->crtc_enabled = false;
+	drm_crtc_vblank_off(crtc);
+
+	spin_lock_irqsave(&crtc->dev->event_lock, flags);
+	pending = disp->event != NULL;
+	spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+
+	if (!wait_event_timeout(disp->flip_wait, !pending,
+				msecs_to_jiffies(50))) {
+		DRM_WARN("VDRM: page flip timeout\n");
+		vdrm_drv_finish_page_flip_internal(disp);
+	}
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (crtc->state->event) {
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+}
+
+static const struct drm_crtc_helper_funcs vdrm_crtc_helper_funcs = {
+	.atomic_check = vdrm_crtc_check,
+	.atomic_flush = vdrm_crtc_flush,
+	.atomic_enable = vdrm_crtc_enable,
+	.atomic_disable = vdrm_crtc_disable,
+};
+
+static int vdrm_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+	struct vdrm_display *disp;
+
+	disp = crtc_to_vdrm_display(crtc);
+	disp->vblank_enabled = true;
+
+	return 0;
+}
+
+static void vdrm_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+	struct vdrm_display *disp;
+
+	disp = crtc_to_vdrm_display(crtc);
+	disp->vblank_enabled = false;
+}
+
+static const struct drm_crtc_funcs vdrm_crtc_funcs = {
+	.reset = drm_atomic_helper_crtc_reset,
+	.destroy = drm_crtc_cleanup,
+	.set_config = drm_atomic_helper_set_config,
+	.page_flip = drm_atomic_helper_page_flip,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+	.enable_vblank = vdrm_crtc_enable_vblank,
+	.disable_vblank = vdrm_crtc_disable_vblank,
+};
+static const struct drm_encoder_funcs vdrm_encoder_funcs = {
+	.destroy = drm_encoder_cleanup,
+};
+
+static int vdrm_properties_init(struct vdrm_device *vdrm, int num_props,
+				struct vdrm_property_info *props)
+{
+	int i;
+	unsigned int w = vdrm->ddev.mode_config.max_width;
+	unsigned int h = vdrm->ddev.mode_config.max_height;
+
+	vdrm->plane_props.offset_x =
+		drm_property_create_range(&vdrm->ddev, 0, "vdrm_offset_x", 0, w);
+	if (!vdrm->plane_props.offset_x)
+		return -1;
+	vdrm->plane_props.offset_y =
+		drm_property_create_range(&vdrm->ddev, 0, "vdrm_offset_y", 0, h);
+	if (!vdrm->plane_props.offset_y)
+		return -1;
+	vdrm->plane_props.width =
+		drm_property_create_range(&vdrm->ddev, 0, "vdrm_width", 1, w);
+	if (!vdrm->plane_props.width)
+		return -1;
+	vdrm->plane_props.height =
+		drm_property_create_range(&vdrm->ddev, 0, "vdrm_height", 1, h);
+	if (!vdrm->plane_props.height)
+		return -1;
+
+	if (num_props == 0)
+		return 0;
+
+	vdrm->props = devm_kzalloc(vdrm->parent->dev,
+				    sizeof(*vdrm->props) * num_props,
+				    GFP_KERNEL);
+	if (!vdrm->props)
+		return -ENOMEM;
+
+	for (i = 0; i < num_props; i++) {
+		struct drm_property *p = props[i].prop;
+
+		vdrm->props[i].prop =
+			drm_property_create_range(&vdrm->ddev, p->flags,
+						  p->name, p->values[0],
+						  p->values[1]);
+		if (!vdrm->props[i].prop)
+			goto err;
+
+		vdrm->props[i].parent_prop = p;
+		vdrm->props[i].default_val = props[i].default_val;
+	}
+	vdrm->num_props = num_props;
+
+	return 0;
+
+err:
+	for (i--; i >= 0; i--)
+		drm_property_destroy(&vdrm->ddev, vdrm->props[i].prop);
+	devm_kfree(vdrm->parent->dev, vdrm->props);
+	return -1;
+}
+
+static int vdrm_of_get_plane(struct device_node *np,
+			     int *x, int *y, int *width, int *height, int *z)
+{
+	struct device_node *child;
+	int ret;
+
+	child = of_get_next_child(np, NULL);
+	if (!child)
+		return -ENODEV;
+
+	ret = of_property_read_u32(child, "x", x);
+	ret |= of_property_read_u32(child, "y", y);
+	ret |= of_property_read_u32(child, "width", width);
+	ret |= of_property_read_u32(child, "height", height);
+	ret |= of_property_read_u32(child, "zpos", z);
+
+	of_node_put(child);
+	return ret;
+}
+
+static void vdrm_dump(struct vdrm_device *vdrm)
+{
+	struct vdrm_display *disp;
+
+	DRM_INFO("Virtual DRM Info:\n");
+	list_for_each_entry(disp, &vdrm->disps, head) {
+		DRM_INFO("\tCONNECTOR: %d\n",
+			 disp->connector.base.id);
+		DRM_INFO("\tCRTC: %d\n",
+			 disp->crtc.base.id);
+		DRM_INFO("\tENCODER: %d\n",
+			 disp->encoder.base.id);
+		DRM_INFO("\tPLANE: %d\n",
+			 disp->plane->base.id);
+		DRM_INFO("\tParent CRTC: %d\n",
+			 disp->parent_crtc->base.id);
+	}
+}
+
+/**
+ * vdrm_drv_handle_vblank - handle a vblank event for vDRM
+ * @vdisplay: vDRM display object
+ */
+void vdrm_drv_handle_vblank(struct vdrm_display *vdisplay)
+{
+	if (vdisplay->vblank_enabled)
+		drm_crtc_handle_vblank(&vdisplay->crtc);
+}
+
+/**
+ * vdrm_drv_finish_page_flip - handle a page flip event for vDRM
+ * @vdisplay: vDRM display object
+ */
+void vdrm_drv_finish_page_flip(struct vdrm_display *vdisplay)
+{
+	vdrm_drv_finish_page_flip_internal(vdisplay);
+}
+
+DEFINE_DRM_GEM_CMA_FOPS(vdrm_fops);
+
+static struct drm_driver vdrm_driver = {
+	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.dumb_create = vdrm_dumb_create,
+	.fops = &vdrm_fops,
+	.name = "virt-drm",
+	.desc = "Virtual DRM driver",
+	.date = "20201104",
+	.major = 1,
+	.minor = 0,
+};
+
+/**
+ * vdrm_drv_init - Initialize vDRM device
+ * @dev: parent DRM device
+ * @np: vDRM device node in DTB
+ * @num_props: number of parent property objects
+ * @props: parent plane properties used in vDRM
+ * @funcs: callbacks for vDRM
+ *
+ * Allocates a new vDRM device, initializes mode_config of the vDRM device
+ * and allocates property objects. Not initialize plane, crtc, encoder and
+ * connector. Initialization of plane must be done in vdrm_drv_plane_init()
+ * and initialization of crtc, encoder and connector must be done by
+ * vdrm_drv_display_init(). Also, after initializing the plane, crtc,
+ * connector, and encoder, register vDRM device must be done by
+ * vdrm_drv_register().
+ *
+ * Returns:
+ * vDRM object (&vdrm_device) on success, error code encoded into the pointer
+ * on failure.
+ */
+struct vdrm_device *vdrm_drv_init(struct drm_device *dev,
+				  struct device_node *np, int num_props,
+				  struct vdrm_property_info *props,
+				  const struct vdrm_funcs *funcs)
+{
+	struct vdrm_device *vdrm;
+	struct vdrm_plane_info plane_info;
+	int ret;
+
+	if (!of_device_is_compatible(np, "virt-drm"))
+		return ERR_PTR(-ENODEV);
+
+	/* get plane information from device tree */
+	ret = vdrm_of_get_plane(np, &plane_info.x, &plane_info.y,
+				&plane_info.width, &plane_info.height,
+				&plane_info.z);
+	if (ret < 0) {
+		DRM_WARN("VDRM: failed get plane node of %s\n",
+			 of_node_full_name(np));
+		return ERR_PTR(ret);
+	}
+
+	vdrm_driver.prime_handle_to_fd = dev->driver->prime_handle_to_fd;
+	vdrm_driver.prime_fd_to_handle = dev->driver->prime_fd_to_handle;
+	vdrm_driver.gem_prime_import_sg_table =
+		dev->driver->gem_prime_import_sg_table;
+	vdrm_driver.gem_prime_mmap = dev->driver->gem_prime_mmap;
+
+	vdrm = devm_drm_dev_alloc(dev->dev, &vdrm_driver, struct vdrm_device,
+				  ddev);
+	if (IS_ERR(vdrm))
+		return vdrm;
+
+	vdrm->parent = dev;
+	vdrm->funcs = funcs;
+	vdrm->of_plane_info = plane_info;
+
+	INIT_LIST_HEAD(&vdrm->disps);
+
+	ret = drmm_mode_config_init(&vdrm->ddev);
+	if (ret)
+		goto failed;
+
+	vdrm->ddev.mode_config.min_width = 0;
+	vdrm->ddev.mode_config.min_height = 0;
+	vdrm->ddev.mode_config.max_width = 8190;
+	vdrm->ddev.mode_config.max_height = 8190;
+	vdrm->ddev.mode_config.normalize_zpos = true;
+	vdrm->ddev.mode_config.funcs = &vdrm_mode_config_funcs;
+
+	ret = vdrm_properties_init(vdrm, num_props, props);
+	if (ret < 0)
+		goto failed;
+
+	drm_dev_set_unique(&vdrm->ddev, of_node_full_name(np));
+	return vdrm;
+
+failed:
+	kfree(vdrm);
+	return ERR_PTR(ret);
+}
+
+/**
+ * vdrm_drv_plane_init - Initialize the plane used by vDRM
+ * @vdrm: vDRM object
+ * @plane: plane to assign to vDRM
+ * @funcs: callbacks for the plane
+ * @helper_funcs: helper vtable to set for plane
+ * @formats: color formats
+ * @num_formats: number of color formats
+ * @max_zpos: max value for zpos property of plane
+ *
+ * Initializes a plane object of PRIMARY type by drm_universal_plane_init()
+ * and initializes @plane's properties. The property passed by vdrm_drv_init()
+ * is set to @plane.
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int vdrm_drv_plane_init(struct vdrm_device *vdrm, struct drm_plane *plane,
+			const struct drm_plane_funcs *funcs,
+			const struct drm_plane_helper_funcs *helper_funcs,
+			const u32 *formats, unsigned int num_formats,
+			int max_zpos)
+{
+	struct vdrm_display *disp;
+	int i, ret;
+
+	disp = kzalloc(sizeof(*disp), GFP_KERNEL);
+	if (!disp)
+		return -ENOMEM;
+
+	disp->dev = vdrm;
+	disp->plane = plane;
+	disp->plane_info = vdrm->of_plane_info;
+
+	disp->parent_plane_funcs = funcs;
+	disp->parent_plane_helper_funcs = helper_funcs;
+	disp->plane_funcs = *funcs;
+	disp->plane_helper_funcs = *helper_funcs;
+
+	disp->plane_funcs.reset = vdrm_plane_reset;
+	disp->plane_funcs.atomic_set_property = vdrm_plane_set_property;
+	disp->plane_funcs.atomic_get_property = vdrm_plane_get_property;
+	disp->plane_helper_funcs.atomic_update = vdrm_plane_update;
+
+	drm_plane_helper_add(disp->plane, &disp->plane_helper_funcs);
+	ret = drm_universal_plane_init(&vdrm->ddev, plane, 0,
+				       &disp->plane_funcs, formats,
+				       num_formats, NULL,
+				       DRM_PLANE_TYPE_PRIMARY, NULL);
+	if (ret) {
+		kfree(disp);
+		return ret;
+	}
+
+	drm_plane_create_alpha_property(plane);
+	drm_plane_create_zpos_property(plane, disp->plane_info.z, 0, max_zpos);
+	drm_object_attach_property(&plane->base,
+				   vdrm->plane_props.offset_x,
+				   disp->plane_info.x);
+	drm_object_attach_property(&plane->base,
+				   vdrm->plane_props.offset_y,
+				   disp->plane_info.y);
+	drm_object_attach_property(&plane->base,
+				   vdrm->plane_props.width,
+				   disp->plane_info.width);
+	drm_object_attach_property(&plane->base,
+				   vdrm->plane_props.height,
+				   disp->plane_info.height);
+	for (i = 0; i < vdrm->num_props; i++) {
+		drm_object_attach_property(&plane->base,
+					   vdrm->props[i].prop,
+					   vdrm->props[i].default_val);
+	}
+
+	INIT_LIST_HEAD(&disp->head);
+	list_add_tail(&disp->head, &vdrm->disps);
+	vdrm->num_crtcs++;
+	return 0;
+}
+
+/**
+ * vdrm_drv_display_init - Initialize the vDRM display object
+ * @vdrm: vDRM object
+ * @crtc: parent crtc to be linked with the vDRM crtc
+ * @plane: plane assigned to vDRM
+ *
+ * Initializes crtc, connector and encorder, and links @crtc to crtc of vDRM.
+ *
+ * Returns:
+ * vDRM display object on success, error code encoded into the pointer on
+ * failure.
+ */
+struct vdrm_display *vdrm_drv_display_init(struct vdrm_device *vdrm,
+					   struct drm_crtc *crtc,
+					   struct drm_plane *plane)
+{
+	struct vdrm_display *disp;
+	int ret;
+
+	disp = vdrm_plane_find_display(vdrm, plane);
+	if (!disp)
+		return ERR_PTR(-EINVAL);
+
+	drm_crtc_helper_add(&disp->crtc, &vdrm_crtc_helper_funcs);
+	ret = drm_crtc_init_with_planes(&vdrm->ddev, &disp->crtc, plane, NULL,
+					&vdrm_crtc_funcs, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	drm_connector_helper_add(&disp->connector, &vdrm_conn_helper_funcs);
+	ret = drm_connector_init(&vdrm->ddev, &disp->connector,
+				 &vdrm_conn_funcs, DRM_MODE_CONNECTOR_VIRTUAL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	disp->encoder.possible_crtcs = drm_crtc_mask(&disp->crtc);
+	ret = drm_encoder_init(&vdrm->ddev, &disp->encoder, &vdrm_encoder_funcs,
+			       DRM_MODE_ENCODER_NONE, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ret = drm_connector_attach_encoder(&disp->connector, &disp->encoder);
+	if (ret)
+		return ERR_PTR(ret);
+
+	init_waitqueue_head(&disp->flip_wait);
+	disp->parent_crtc = crtc;
+
+	return disp;
+}
+
+/**
+ * vdrm_drv_register - Register vDRM device
+ * @vdrm: vDRM object
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int vdrm_drv_register(struct vdrm_device *vdrm)
+{
+	int ret;
+	struct drm_device *dev = &vdrm->ddev;
+
+	ret = drm_vblank_init(dev, vdrm->num_crtcs);
+	if (ret)
+		return ret;
+
+	drm_mode_config_reset(dev);
+
+	ret = drm_dev_register(dev, 0);
+	if (ret)
+		return ret;
+
+	dev->irq_enabled = true;
+
+	DRM_INFO("Virtual Device is initialized.\n");
+
+	vdrm_dump(vdrm);
+
+	return 0;
+}
+
+/**
+ * vdrm_drv_fini - release vDRM resources
+ * @vdrm: vDRM object
+ */
+void vdrm_drv_fini(struct vdrm_device *vdrm)
+{
+	struct vdrm_display *disp;
+
+	if (vdrm->ddev.registered)
+		drm_dev_unregister(&vdrm->ddev);
+	drm_mode_config_cleanup(&vdrm->ddev);
+
+	list_for_each_entry(disp, &vdrm->disps, head)
+		kfree(disp);
+}
diff --git a/drivers/gpu/drm/vdrm/vdrm_drv.h b/drivers/gpu/drm/vdrm/vdrm_drv.h
new file mode 100644
index 000000000000..67b8e02efddf
--- /dev/null
+++ b/drivers/gpu/drm/vdrm/vdrm_drv.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * vdrm_drv.h -- Virtual DRM driver
+ *
+ * Copyright (C) 2021 Renesas Electronics Corporation
+ */
+
+#ifndef __VDRM_DRV_H__
+#define __VDRM_DRV_H__
+
+#include <drm/drm_device.h>
+
+#include "vdrm_api.h"
+
+struct vdrm_property {
+	struct drm_property *prop;
+	struct drm_property *parent_prop;
+	uint64_t default_val;
+};
+
+struct vdrm_plane_info {
+	int x;
+	int y;
+	unsigned int width;
+	unsigned int height;
+	unsigned int z;
+};
+
+struct vdrm_device;
+
+struct vdrm_display {
+	struct drm_connector connector;
+	struct drm_crtc crtc;
+	struct drm_crtc *parent_crtc;
+	struct drm_plane *plane;
+	struct drm_encoder encoder;
+	struct drm_pending_vblank_event *event;
+	struct vdrm_device *dev;
+	bool vblank_enabled;
+	wait_queue_head_t flip_wait;
+	bool crtc_enabled;
+	int vblank_count;
+
+	struct list_head head;
+
+	struct vdrm_plane_info plane_info;
+
+	const struct drm_plane_funcs *parent_plane_funcs;
+	const struct drm_plane_helper_funcs *parent_plane_helper_funcs;
+	struct drm_plane_funcs plane_funcs;
+	struct drm_plane_helper_funcs plane_helper_funcs;
+};
+
+struct vdrm_device {
+	struct drm_device ddev;
+	struct drm_device *parent;
+
+	int num_crtcs;
+	struct list_head disps;
+
+	const struct vdrm_funcs *funcs;
+	struct vdrm_property *props;
+	int num_props;
+
+	struct {
+		struct drm_property *offset_x;
+		struct drm_property *offset_y;
+		struct drm_property *width;
+		struct drm_property *height;
+	} plane_props;
+
+	struct vdrm_plane_info of_plane_info;
+};
+
+static inline struct vdrm_device *to_vdrm_device(struct drm_device *dev)
+{
+	return container_of(dev, struct vdrm_device, ddev);
+}
+
+#endif /* __VDRM_DRV_H__ */
-- 
2.25.1