text: // SPDX-License-Identifier: GPL-2.0 OR MIT
  
  /*
   *  Xen para-virtual DRM device
   *
   * Copyright (C) 2016-2018 EPAM Systems Inc.
   *
   * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
   */
  
  #include <drm/drm_atomic.h>
  #include <drm/drm_atomic_helper.h>
  #include <drm/drm_drv.h>
  #include <drm/drm_fourcc.h>
  #include <drm/drm_gem.h>
  #include <drm/drm_gem_framebuffer_helper.h>
  #include <drm/drm_probe_helper.h>
  #include <drm/drm_vblank.h>
  
  #include "xen_drm_front.h"
  #include "xen_drm_front_conn.h"
  #include "xen_drm_front_kms.h"
  
  /*
   * Timeout in ms to wait for frame done event from the backend:
   * must be a bit more than IO time-out
   */
  #define FRAME_DONE_TO_MS	(XEN_DRM_FRONT_WAIT_BACK_MS + 100)
  
  static struct xen_drm_front_drm_pipeline *
  to_xen_drm_pipeline(struct drm_simple_display_pipe *pipe)
  {
  	return container_of(pipe, struct xen_drm_front_drm_pipeline, pipe);
  }
  
  static void fb_destroy(struct drm_framebuffer *fb)
  {
  	struct xen_drm_front_drm_info *drm_info = fb->dev->dev_private;
  	int idx;
  
  	if (drm_dev_enter(fb->dev, &idx)) {
  		xen_drm_front_fb_detach(drm_info->front_info,
  					xen_drm_front_fb_to_cookie(fb));
  		drm_dev_exit(idx);
  	}
  	drm_gem_fb_destroy(fb);
  }
  
  static const struct drm_framebuffer_funcs fb_funcs = {
  	.destroy = fb_destroy,
  };
  
  static struct drm_framebuffer *
  fb_create(struct drm_device *dev, struct drm_file *filp,
  	  const struct drm_mode_fb_cmd2 *mode_cmd)
  {
  	struct xen_drm_front_drm_info *drm_info = dev->dev_private;
  	struct drm_framebuffer *fb;
  	struct drm_gem_object *gem_obj;
  	int ret;
  
  	fb = drm_gem_fb_create_with_funcs(dev, filp, mode_cmd, &fb_funcs);
  	if (IS_ERR_OR_NULL(fb))
  		return fb;
  
  	gem_obj = fb->obj[0];
  
  	ret = xen_drm_front_fb_attach(drm_info->front_info,
  				      xen_drm_front_dbuf_to_cookie(gem_obj),
  				      xen_drm_front_fb_to_cookie(fb),
  				      fb->width, fb->height,
  				      fb->format->format);
  	if (ret < 0) {
  		DRM_ERROR("Back failed to attach FB %p: %d\n", fb, ret);
  		goto fail;
  	}
  
  	return fb;
  
  fail:
  	drm_gem_fb_destroy(fb);
  	return ERR_PTR(ret);
  }
  
  static const struct drm_mode_config_funcs mode_config_funcs = {
  	.fb_create = fb_create,
  	.atomic_check = drm_atomic_helper_check,
  	.atomic_commit = drm_atomic_helper_commit,
  };
  
  static void send_pending_event(struct xen_drm_front_drm_pipeline *pipeline)
  {
  	struct drm_crtc *crtc = &pipeline->pipe.crtc;
  	struct drm_device *dev = crtc->dev;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->event_lock, flags);
  	if (pipeline->pending_event)
  		drm_crtc_send_vblank_event(crtc, pipeline->pending_event);
  	pipeline->pending_event = NULL;
  	spin_unlock_irqrestore(&dev->event_lock, flags);
  }
  
  static void display_enable(struct drm_simple_display_pipe *pipe,
  			   struct drm_crtc_state *crtc_state,
  			   struct drm_plane_state *plane_state)
  {
  	struct xen_drm_front_drm_pipeline *pipeline =
  			to_xen_drm_pipeline(pipe);
  	struct drm_crtc *crtc = &pipe->crtc;
  	struct drm_framebuffer *fb = plane_state->fb;
  	int ret, idx;
  
  	if (!drm_dev_enter(pipe->crtc.dev, &idx))
  		return;
  
  	ret = xen_drm_front_mode_set(pipeline, crtc->x, crtc->y,
  				     fb->width, fb->height,
  				     fb->format->cpp[0] * 8,
  				     xen_drm_front_fb_to_cookie(fb));
  
  	if (ret) {
  		DRM_ERROR("Failed to enable display: %d\n", ret);
  		pipeline->conn_connected = false;
  	}
  
  	drm_dev_exit(idx);
  }
  
  static void display_disable(struct drm_simple_display_pipe *pipe)
  {
  	struct xen_drm_front_drm_pipeline *pipeline =
  			to_xen_drm_pipeline(pipe);
  	int ret = 0, idx;
  
  	if (drm_dev_enter(pipe->crtc.dev, &idx)) {
  		ret = xen_drm_front_mode_set(pipeline, 0, 0, 0, 0, 0,
  					     xen_drm_front_fb_to_cookie(NULL));
  		drm_dev_exit(idx);
  	}
  	if (ret)
  		DRM_ERROR("Failed to disable display: %d\n", ret);
  
  	/* Make sure we can restart with enabled connector next time */
  	pipeline->conn_connected = true;
  
  	/* release stalled event if any */
  	send_pending_event(pipeline);
  }
  
  void xen_drm_front_kms_on_frame_done(struct xen_drm_front_drm_pipeline *pipeline,
  				     u64 fb_cookie)
  {
  	/*
  	 * This runs in interrupt context, e.g. under
  	 * drm_info->front_info->io_lock, so we cannot call _sync version
  	 * to cancel the work
  	 */
  	cancel_delayed_work(&pipeline->pflip_to_worker);
  
  	send_pending_event(pipeline);
  }
  
  static void pflip_to_worker(struct work_struct *work)
  {
  	struct delayed_work *delayed_work = to_delayed_work(work);
  	struct xen_drm_front_drm_pipeline *pipeline =
  			container_of(delayed_work,
  				     struct xen_drm_front_drm_pipeline,
  				     pflip_to_worker);
  
  	DRM_ERROR("Frame done timed-out, releasing");
  	send_pending_event(pipeline);
  }
  
  static bool display_send_page_flip(struct drm_simple_display_pipe *pipe,
  				   struct drm_plane_state *old_plane_state)
  {
  	struct drm_plane_state *plane_state =
  			drm_atomic_get_new_plane_state(old_plane_state->state,
  						       &pipe->plane);
  
  	/*
  	 * If old_plane_state->fb is NULL and plane_state->fb is not,
  	 * then this is an atomic commit which will enable display.
  	 * If old_plane_state->fb is not NULL and plane_state->fb is,
  	 * then this is an atomic commit which will disable display.
  	 * Ignore these and do not send page flip as this framebuffer will be
  	 * sent to the backend as a part of display_set_config call.
  	 */
  	if (old_plane_state->fb && plane_state->fb) {
  		struct xen_drm_front_drm_pipeline *pipeline =
  				to_xen_drm_pipeline(pipe);
  		struct xen_drm_front_drm_info *drm_info = pipeline->drm_info;
  		int ret;
  
  		schedule_delayed_work(&pipeline->pflip_to_worker,
  				      msecs_to_jiffies(FRAME_DONE_TO_MS));
  
  		ret = xen_drm_front_page_flip(drm_info->front_info,
  					      pipeline->index,
  					      xen_drm_front_fb_to_cookie(plane_state->fb));
  		if (ret) {
  			DRM_ERROR("Failed to send page flip request to backend: %d\n", ret);
  
  			pipeline->conn_connected = false;
  			/*
  			 * Report the flip not handled, so pending event is
  			 * sent, unblocking user-space.
  			 */
  			return false;
  		}
  		/*
  		 * Signal that page flip was handled, pending event will be sent
  		 * on frame done event from the backend.
  		 */
  		return true;
  	}
  
  	return false;
  }
  
  static int display_check(struct drm_simple_display_pipe *pipe,
  			 struct drm_plane_state *plane_state,
  			 struct drm_crtc_state *crtc_state)
  {
  	/*
  	 * Xen doesn't initialize vblanking via drm_vblank_init(), so
  	 * DRM helpers assume that it doesn't handle vblanking and start
  	 * sending out fake VBLANK events automatically.
  	 *
  	 * As xen contains it's own logic for sending out VBLANK events
  	 * in send_pending_event(), disable no_vblank (i.e., the xen
  	 * driver has vblanking support).
  	 */
  	crtc_state->no_vblank = false;
  
  	return 0;
  }
  
  static void display_update(struct drm_simple_display_pipe *pipe,
  			   struct drm_plane_state *old_plane_state)
  {
  	struct xen_drm_front_drm_pipeline *pipeline =
  			to_xen_drm_pipeline(pipe);
  	struct drm_crtc *crtc = &pipe->crtc;
  	struct drm_pending_vblank_event *event;
  	int idx;
  
  	event = crtc->state->event;
  	if (event) {
  		struct drm_device *dev = crtc->dev;
  		unsigned long flags;
  
  		WARN_ON(pipeline->pending_event);
  
  		spin_lock_irqsave(&dev->event_lock, flags);
  		crtc->state->event = NULL;
  
  		pipeline->pending_event = event;
  		spin_unlock_irqrestore(&dev->event_lock, flags);
  	}
  
  	if (!drm_dev_enter(pipe->crtc.dev, &idx)) {
  		send_pending_event(pipeline);
  		return;
  	}
  
  	/*
  	 * Send page flip request to the backend *after* we have event cached
  	 * above, so on page flip done event from the backend we can
  	 * deliver it and there is no race condition between this code and
  	 * event from the backend.
  	 * If this is not a page flip, e.g. no flip done event from the backend
  	 * is expected, then send now.
  	 */
  	if (!display_send_page_flip(pipe, old_plane_state))
  		send_pending_event(pipeline);
  
  	drm_dev_exit(idx);
  }
  
  static enum drm_mode_status
  display_mode_valid(struct drm_simple_display_pipe *pipe,
  		   const struct drm_display_mode *mode)
  {
  	struct xen_drm_front_drm_pipeline *pipeline =
  			container_of(pipe, struct xen_drm_front_drm_pipeline,
  				     pipe);
  
  	if (mode->hdisplay != pipeline->width)
  		return MODE_ERROR;
  
  	if (mode->vdisplay != pipeline->height)
  		return MODE_ERROR;
  
  	return MODE_OK;
  }
  
  static const struct drm_simple_display_pipe_funcs display_funcs = {
  	.mode_valid = display_mode_valid,
  	.enable = display_enable,
  	.disable = display_disable,
  	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
  	.check = display_check,
  	.update = display_update,
  };
  
  static int display_pipe_init(struct xen_drm_front_drm_info *drm_info,
  			     int index, struct xen_drm_front_cfg_connector *cfg,
  			     struct xen_drm_front_drm_pipeline *pipeline)
  {
  	struct drm_device *dev = drm_info->drm_dev;
  	const u32 *formats;
  	int format_count;
  	int ret;
  
  	pipeline->drm_info = drm_info;
  	pipeline->index = index;
  	pipeline->height = cfg->height;
  	pipeline->width = cfg->width;
  
  	INIT_DELAYED_WORK(&pipeline->pflip_to_worker, pflip_to_worker);
  
  	ret = xen_drm_front_conn_init(drm_info, &pipeline->conn);
  	if (ret)
  		return ret;
  
  	formats = xen_drm_front_conn_get_formats(&format_count);
  
  	return drm_simple_display_pipe_init(dev, &pipeline->pipe,
  					    &display_funcs, formats,
  					    format_count, NULL,
  					    &pipeline->conn);
  }
  
  int xen_drm_front_kms_init(struct xen_drm_front_drm_info *drm_info)
  {
  	struct drm_device *dev = drm_info->drm_dev;
  	int i, ret;
  
  	drm_mode_config_init(dev);
  
  	dev->mode_config.min_width = 0;
  	dev->mode_config.min_height = 0;
  	dev->mode_config.max_width = 4095;
  	dev->mode_config.max_height = 2047;
  	dev->mode_config.funcs = &mode_config_funcs;
  
  	for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
  		struct xen_drm_front_cfg_connector *cfg =
  				&drm_info->front_info->cfg.connectors[i];
  		struct xen_drm_front_drm_pipeline *pipeline =
  				&drm_info->pipeline[i];
  
  		ret = display_pipe_init(drm_info, i, cfg, pipeline);
  		if (ret) {
  			drm_mode_config_cleanup(dev);
  			return ret;
  		}
  	}
  
  	drm_mode_config_reset(dev);
  	drm_kms_helper_poll_init(dev);
  	return 0;
  }
  
  void xen_drm_front_kms_fini(struct xen_drm_front_drm_info *drm_info)
  {
  	int i;
  
  	for (i = 0; i < drm_info->front_info->cfg.num_connectors; i++) {
  		struct xen_drm_front_drm_pipeline *pipeline =
  				&drm_info->pipeline[i];
  
  		cancel_delayed_work_sync(&pipeline->pflip_to_worker);
  
  		send_pending_event(pipeline);
  	}
  }
  