/*
   * Copyright (C) 2014 Red Hat
   * Author: Rob Clark <robdclark@gmail.com>
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   * OTHER DEALINGS IN THE SOFTWARE.
   */
  
  #ifndef DRM_MODESET_LOCK_H_
  #define DRM_MODESET_LOCK_H_
  
  #include <linux/ww_mutex.h>
  
  struct drm_modeset_lock;
  
  /**

   * struct drm_modeset_acquire_ctx - locking context (see ww_acquire_ctx)

   * @ww_ctx: base acquire ctx
   * @contended: used internally for -EDEADLK handling
   * @locked: list of held locks

   * @trylock_only: trylock mode used in atomic contexts/panic notifiers

   *
   * Each thread competing for a set of locks must use one acquire
   * ctx.  And if any lock fxn returns -EDEADLK, it must backoff and
   * retry.
   */
  struct drm_modeset_acquire_ctx {
  
  	struct ww_acquire_ctx ww_ctx;

  	/*

  	 * Contended lock: if a lock is contended you should only call
  	 * drm_modeset_backoff() which drops locks and slow-locks the
  	 * contended lock.
  	 */
  	struct drm_modeset_lock *contended;

  	/*

  	 * list of held locks (drm_modeset_lock)
  	 */
  	struct list_head locked;

  	/*

  	 * Trylock mode, use only for panic handlers!
  	 */
  	bool trylock_only;

  };
  
  /**

   * struct drm_modeset_lock - used for locking modeset resources.

   * @mutex: resource locking
   * @head: used to hold it's place on state->locked list when
   *    part of an atomic update
   *
   * Used for locking CRTCs and other modeset resources.
   */
  struct drm_modeset_lock {

  	/*

  	 * modeset lock
  	 */
  	struct ww_mutex mutex;

  	/*

  	 * Resources that are locked as part of an atomic update are added
  	 * to a list (so we know what to unlock at the end).
  	 */
  	struct list_head head;
  };
  
  extern struct ww_class crtc_ww_class;
  
  void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
  		uint32_t flags);
  void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
  void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
  void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
  int drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
  
  /**
   * drm_modeset_lock_init - initialize lock
   * @lock: lock to init
   */
  static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
  {
  	ww_mutex_init(&lock->mutex, &crtc_ww_class);
  	INIT_LIST_HEAD(&lock->head);
  }
  
  /**
   * drm_modeset_lock_fini - cleanup lock
   * @lock: lock to cleanup
   */
  static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
  {
  	WARN_ON(!list_empty(&lock->head));
  }
  
  /**
   * drm_modeset_is_locked - equivalent to mutex_is_locked()
   * @lock: lock to check
   */
  static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
  {
  	return ww_mutex_is_locked(&lock->mutex);
  }
  
  int drm_modeset_lock(struct drm_modeset_lock *lock,
  		struct drm_modeset_acquire_ctx *ctx);
  int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
  		struct drm_modeset_acquire_ctx *ctx);
  void drm_modeset_unlock(struct drm_modeset_lock *lock);
  
  struct drm_device;

  struct drm_crtc;

  struct drm_plane;

  
  void drm_modeset_lock_all(struct drm_device *dev);
  void drm_modeset_unlock_all(struct drm_device *dev);

  void drm_modeset_lock_crtc(struct drm_crtc *crtc,
  			   struct drm_plane *plane);

  void drm_modeset_unlock_crtc(struct drm_crtc *crtc);

  void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);

  struct drm_modeset_acquire_ctx *
  drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);

  int drm_modeset_lock_all_ctx(struct drm_device *dev,
  			     struct drm_modeset_acquire_ctx *ctx);

  
  #endif /* DRM_MODESET_LOCK_H_ */