/*
   * Header file for reservations for dma-buf and ttm
   *
   * Copyright(C) 2011 Linaro Limited. All rights reserved.
   * Copyright (C) 2012-2013 Canonical Ltd
   * Copyright (C) 2012 Texas Instruments
   *
   * Authors:

   * Rob Clark <robdclark@gmail.com>

   * Maarten Lankhorst <maarten.lankhorst@canonical.com>
   * Thomas Hellstrom <thellstrom-at-vmware-dot-com>
   *
   * Based on bo.c which bears the following copyright notice,
   * but is dual licensed:
   *
   * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   * All Rights Reserved.
   *
   * 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, sub license, 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 (including the
   * next paragraph) 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 NON-INFRINGEMENT. IN NO EVENT SHALL
   * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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 _LINUX_RESERVATION_H
  #define _LINUX_RESERVATION_H

  #include <linux/ww_mutex.h>

  #include <linux/dma-fence.h>

  #include <linux/slab.h>

  #include <linux/seqlock.h>
  #include <linux/rcupdate.h>

  
  extern struct ww_class reservation_ww_class;

  /**

   * struct dma_resv_list - a list of shared fences

   * @rcu: for internal use
   * @shared_count: table of shared fences
   * @shared_max: for growing shared fence table
   * @shared: shared fence table
   */

  struct dma_resv_list {

  	struct rcu_head rcu;

  	u32 shared_count, shared_max;

  	struct dma_fence __rcu *shared[];

  };

  /**

   * struct dma_resv - a reservation object manages fences for a buffer

   * @lock: update side lock
   * @seq: sequence count for managing RCU read-side synchronization
   * @fence_excl: the exclusive fence, if there is one currently
   * @fence: list of current shared fences

   */

  struct dma_resv {

  	struct ww_mutex lock;

  	seqcount_ww_mutex_t seq;

  	struct dma_fence __rcu *fence_excl;

  	struct dma_resv_list __rcu *fence;

  };

  #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
  #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)

  /**

   * dma_resv_get_list - get the reservation object's

   * shared fence list, with update-side lock held
   * @obj: the reservation object
   *
   * Returns the shared fence list.  Does NOT take references to
   * the fence.  The obj->lock must be held.
   */

  static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)

  {

  	return rcu_dereference_protected(obj->fence,

  					 dma_resv_held(obj));

  }

  /**

   * dma_resv_lock - lock the reservation object

   * @obj: the reservation object
   * @ctx: the locking context
   *
   * Locks the reservation object for exclusive access and modification. Note,
   * that the lock is only against other writers, readers will run concurrently
   * with a writer under RCU. The seqlock is used to notify readers if they
   * overlap with a writer.
   *
   * As the reservation object may be locked by multiple parties in an
   * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
   * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
   * object may be locked by itself by passing NULL as @ctx.
   */

  static inline int dma_resv_lock(struct dma_resv *obj,
  				struct ww_acquire_ctx *ctx)

  {
  	return ww_mutex_lock(&obj->lock, ctx);
  }
  
  /**

   * dma_resv_lock_interruptible - lock the reservation object

   * @obj: the reservation object
   * @ctx: the locking context
   *
   * Locks the reservation object interruptible for exclusive access and
   * modification. Note, that the lock is only against other writers, readers
   * will run concurrently with a writer under RCU. The seqlock is used to
   * notify readers if they overlap with a writer.
   *
   * As the reservation object may be locked by multiple parties in an
   * undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
   * is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
   * object may be locked by itself by passing NULL as @ctx.
   */

  static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
  					      struct ww_acquire_ctx *ctx)

  {
  	return ww_mutex_lock_interruptible(&obj->lock, ctx);
  }

  /**

   * dma_resv_lock_slow - slowpath lock the reservation object

   * @obj: the reservation object
   * @ctx: the locking context
   *
   * Acquires the reservation object after a die case. This function

   * will sleep until the lock becomes available. See dma_resv_lock() as

   * well.
   */

  static inline void dma_resv_lock_slow(struct dma_resv *obj,
  				      struct ww_acquire_ctx *ctx)

  {
  	ww_mutex_lock_slow(&obj->lock, ctx);
  }
  
  /**

   * dma_resv_lock_slow_interruptible - slowpath lock the reservation

   * object, interruptible
   * @obj: the reservation object
   * @ctx: the locking context
   *
   * Acquires the reservation object interruptible after a die case. This function
   * will sleep until the lock becomes available. See

   * dma_resv_lock_interruptible() as well.

   */

  static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
  						   struct ww_acquire_ctx *ctx)

  {
  	return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
  }

  
  /**

   * dma_resv_trylock - trylock the reservation object

   * @obj: the reservation object
   *
   * Tries to lock the reservation object for exclusive access and modification.
   * Note, that the lock is only against other writers, readers will run
   * concurrently with a writer under RCU. The seqlock is used to notify readers
   * if they overlap with a writer.
   *
   * Also note that since no context is provided, no deadlock protection is
   * possible.
   *
   * Returns true if the lock was acquired, false otherwise.
   */

  static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)

  {
  	return ww_mutex_trylock(&obj->lock);
  }
  
  /**

   * dma_resv_is_locked - is the reservation object locked

   * @obj: the reservation object
   *
   * Returns true if the mutex is locked, false if unlocked.
   */

  static inline bool dma_resv_is_locked(struct dma_resv *obj)

  {
  	return ww_mutex_is_locked(&obj->lock);
  }
  
  /**

   * dma_resv_locking_ctx - returns the context used to lock the object

   * @obj: the reservation object
   *
   * Returns the context used to lock a reservation object or NULL if no context
   * was used or the object is not locked at all.
   */

  static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)

  {
  	return READ_ONCE(obj->lock.ctx);
  }
  
  /**

   * dma_resv_unlock - unlock the reservation object

   * @obj: the reservation object
   *
   * Unlocks the reservation object following exclusive access.
   */

  static inline void dma_resv_unlock(struct dma_resv *obj)

  {

  #ifdef CONFIG_DEBUG_MUTEXES
  	/* Test shared fence slot reservation */

  	if (rcu_access_pointer(obj->fence)) {

  		struct dma_resv_list *fence = dma_resv_get_list(obj);

  
  		fence->shared_max = fence->shared_count;
  	}

  #endif

  	ww_mutex_unlock(&obj->lock);
  }

  /**
   * dma_resv_get_excl - get the reservation object's
   * exclusive fence, with update-side lock held
   * @obj: the reservation object
   *
   * Returns the exclusive fence (if any).  Does NOT take a
   * reference. Writers must hold obj->lock, readers may only
   * hold a RCU read side lock.
   *
   * RETURNS
   * The exclusive fence or NULL
   */
  static inline struct dma_fence *
  dma_resv_get_excl(struct dma_resv *obj)
  {
  	return rcu_dereference_protected(obj->fence_excl,
  					 dma_resv_held(obj));
  }
  
  /**
   * dma_resv_get_excl_rcu - get the reservation object's
   * exclusive fence, without lock held.
   * @obj: the reservation object
   *
   * If there is an exclusive fence, this atomically increments it's
   * reference count and returns it.
   *
   * RETURNS
   * The exclusive fence or NULL if none
   */
  static inline struct dma_fence *
  dma_resv_get_excl_rcu(struct dma_resv *obj)
  {
  	struct dma_fence *fence;
  
  	if (!rcu_access_pointer(obj->fence_excl))
  		return NULL;
  
  	rcu_read_lock();
  	fence = dma_fence_get_rcu_safe(&obj->fence_excl);
  	rcu_read_unlock();
  
  	return fence;
  }

  void dma_resv_init(struct dma_resv *obj);
  void dma_resv_fini(struct dma_resv *obj);
  int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
  void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);

  void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);

  int dma_resv_get_fences_rcu(struct dma_resv *obj,
  			    struct dma_fence **pfence_excl,
  			    unsigned *pshared_count,
  			    struct dma_fence ***pshared);

  int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);

  long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
  			       unsigned long timeout);

  bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);

  #endif /* _LINUX_RESERVATION_H */