text: /*
   * Copyright (c) 2016 Intel Corporation
   *
   * Permission to use, copy, modify, distribute, and sell this software and its
   * documentation for any purpose is hereby granted without fee, provided that
   * the above copyright notice appear in all copies and that both that copyright
   * notice and this permission notice appear in supporting documentation, and
   * that the name of the copyright holders not be used in advertising or
   * publicity pertaining to distribution of the software without specific,
   * written prior permission.  The copyright holders make no representations
   * about the suitability of this software for any purpose.  It is provided "as
   * is" without express or implied warranty.
   *
   * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
   * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
   * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
   * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
   * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   * OF THIS SOFTWARE.
   */
  
  #include <linux/export.h>
  #include <drm/drmP.h>
  #include <drm/drm_encoder.h>
  
  #include "drm_crtc_internal.h"
  
  /**
   * DOC: overview
   *
   * Encoders represent the connecting element between the CRTC (as the overall
   * pixel pipeline, represented by &struct drm_crtc) and the connectors (as the
   * generic sink entity, represented by &struct drm_connector). An encoder takes
   * pixel data from a CRTC and converts it to a format suitable for any attached
   * connector. Encoders are objects exposed to userspace, originally to allow
   * userspace to infer cloning and connector/CRTC restrictions. Unfortunately
   * almost all drivers get this wrong, making the uabi pretty much useless. On
   * top of that the exposed restrictions are too simple for today's hardware, and
   * the recommended way to infer restrictions is by using the
   * DRM_MODE_ATOMIC_TEST_ONLY flag for the atomic IOCTL.
   *
   * Otherwise encoders aren't used in the uapi at all (any modeset request from
   * userspace directly connects a connector with a CRTC), drivers are therefore
   * free to use them however they wish. Modeset helper libraries make strong use
   * of encoders to facilitate code sharing. But for more complex settings it is
   * usually better to move shared code into a separate &drm_bridge. Compared to
   * encoders, bridges also have the benefit of being purely an internal
   * abstraction since they are not exposed to userspace at all.
   *
   * Encoders are initialized with drm_encoder_init() and cleaned up using
   * drm_encoder_cleanup().
   */
  static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
  	{ DRM_MODE_ENCODER_NONE, "None" },
  	{ DRM_MODE_ENCODER_DAC, "DAC" },
  	{ DRM_MODE_ENCODER_TMDS, "TMDS" },
  	{ DRM_MODE_ENCODER_LVDS, "LVDS" },
  	{ DRM_MODE_ENCODER_TVDAC, "TV" },
  	{ DRM_MODE_ENCODER_VIRTUAL, "Virtual" },
  	{ DRM_MODE_ENCODER_DSI, "DSI" },
  	{ DRM_MODE_ENCODER_DPMST, "DP MST" },
  	{ DRM_MODE_ENCODER_DPI, "DPI" },
  };
  
  int drm_encoder_register_all(struct drm_device *dev)
  {
  	struct drm_encoder *encoder;
  	int ret = 0;
  
  	drm_for_each_encoder(encoder, dev) {
  		if (encoder->funcs->late_register)
  			ret = encoder->funcs->late_register(encoder);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  
  void drm_encoder_unregister_all(struct drm_device *dev)
  {
  	struct drm_encoder *encoder;
  
  	drm_for_each_encoder(encoder, dev) {
  		if (encoder->funcs->early_unregister)
  			encoder->funcs->early_unregister(encoder);
  	}
  }
  
  /**
   * drm_encoder_init - Init a preallocated encoder
   * @dev: drm device
   * @encoder: the encoder to init
   * @funcs: callbacks for this encoder
   * @encoder_type: user visible type of the encoder
   * @name: printf style format string for the encoder name, or NULL for default name
   *
   * Initialises a preallocated encoder. Encoder should be subclassed as part of
   * driver encoder objects. At driver unload time drm_encoder_cleanup() should be
   * called from the driver's &drm_encoder_funcs.destroy hook.
   *
   * Returns:
   * Zero on success, error code on failure.
   */
  int drm_encoder_init(struct drm_device *dev,
  		     struct drm_encoder *encoder,
  		     const struct drm_encoder_funcs *funcs,
  		     int encoder_type, const char *name, ...)
  {
  	int ret;
  
  	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
  	if (ret)
  		return ret;
  
  	encoder->dev = dev;
  	encoder->encoder_type = encoder_type;
  	encoder->funcs = funcs;
  	if (name) {
  		va_list ap;
  
  		va_start(ap, name);
  		encoder->name = kvasprintf(GFP_KERNEL, name, ap);
  		va_end(ap);
  	} else {
  		encoder->name = kasprintf(GFP_KERNEL, "%s-%d",
  					  drm_encoder_enum_list[encoder_type].name,
  					  encoder->base.id);
  	}
  	if (!encoder->name) {
  		ret = -ENOMEM;
  		goto out_put;
  	}
  
  	list_add_tail(&encoder->head, &dev->mode_config.encoder_list);
  	encoder->index = dev->mode_config.num_encoder++;
  
  out_put:
  	if (ret)
  		drm_mode_object_unregister(dev, &encoder->base);
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_encoder_init);
  
  /**
   * drm_encoder_cleanup - cleans up an initialised encoder
   * @encoder: encoder to cleanup
   *
   * Cleans up the encoder but doesn't free the object.
   */
  void drm_encoder_cleanup(struct drm_encoder *encoder)
  {
  	struct drm_device *dev = encoder->dev;
  
  	/* Note that the encoder_list is considered to be static; should we
  	 * remove the drm_encoder at runtime we would have to decrement all
  	 * the indices on the drm_encoder after us in the encoder_list.
  	 */
  
  	if (encoder->bridge) {
  		struct drm_bridge *bridge = encoder->bridge;
  		struct drm_bridge *next;
  
  		while (bridge) {
  			next = bridge->next;
  			drm_bridge_detach(bridge);
  			bridge = next;
  		}
  	}
  
  	drm_mode_object_unregister(dev, &encoder->base);
  	kfree(encoder->name);
  	list_del(&encoder->head);
  	dev->mode_config.num_encoder--;
  
  	memset(encoder, 0, sizeof(*encoder));
  }
  EXPORT_SYMBOL(drm_encoder_cleanup);
  
  static struct drm_crtc *drm_encoder_get_crtc(struct drm_encoder *encoder)
  {
  	struct drm_connector *connector;
  	struct drm_device *dev = encoder->dev;
  	bool uses_atomic = false;
  	struct drm_connector_list_iter conn_iter;
  
  	/* For atomic drivers only state objects are synchronously updated and
  	 * protected by modeset locks, so check those first. */
  	drm_connector_list_iter_begin(dev, &conn_iter);
  	drm_for_each_connector_iter(connector, &conn_iter) {
  		if (!connector->state)
  			continue;
  
  		uses_atomic = true;
  
  		if (connector->state->best_encoder != encoder)
  			continue;
  
  		drm_connector_list_iter_end(&conn_iter);
  		return connector->state->crtc;
  	}
  	drm_connector_list_iter_end(&conn_iter);
  
  	/* Don't return stale data (e.g. pending async disable). */
  	if (uses_atomic)
  		return NULL;
  
  	return encoder->crtc;
  }
  
  int drm_mode_getencoder(struct drm_device *dev, void *data,
  			struct drm_file *file_priv)
  {
  	struct drm_mode_get_encoder *enc_resp = data;
  	struct drm_encoder *encoder;
  	struct drm_crtc *crtc;
  
  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
  		return -EINVAL;
  
  	encoder = drm_encoder_find(dev, file_priv, enc_resp->encoder_id);
  	if (!encoder)
  		return -ENOENT;
  
  	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
  	crtc = drm_encoder_get_crtc(encoder);
  	if (crtc && drm_lease_held(file_priv, crtc->base.id))
  		enc_resp->crtc_id = crtc->base.id;
  	else
  		enc_resp->crtc_id = 0;
  	drm_modeset_unlock(&dev->mode_config.connection_mutex);
  
  	enc_resp->encoder_type = encoder->encoder_type;
  	enc_resp->encoder_id = encoder->base.id;
  	enc_resp->possible_crtcs = drm_lease_filter_crtcs(file_priv,
  							  encoder->possible_crtcs);
  	enc_resp->possible_clones = encoder->possible_clones;
  
  	return 0;
  }
  