/*
   * fence-array: aggregate fences to be waited together
   *
   * Copyright (C) 2016 Collabora Ltd
   * Copyright (C) 2016 Advanced Micro Devices, Inc.
   * Authors:
   *	Gustavo Padovan <gustavo@padovan.org>
   *	Christian König <christian.koenig@amd.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   */
  
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/fence-array.h>
  
  static void fence_array_cb_func(struct fence *f, struct fence_cb *cb);
  
  static const char *fence_array_get_driver_name(struct fence *fence)
  {
  	return "fence_array";
  }
  
  static const char *fence_array_get_timeline_name(struct fence *fence)
  {
  	return "unbound";
  }
  
  static void fence_array_cb_func(struct fence *f, struct fence_cb *cb)
  {
  	struct fence_array_cb *array_cb =
  		container_of(cb, struct fence_array_cb, cb);
  	struct fence_array *array = array_cb->array;
  
  	if (atomic_dec_and_test(&array->num_pending))
  		fence_signal(&array->base);

  	fence_put(&array->base);

  }
  
  static bool fence_array_enable_signaling(struct fence *fence)
  {
  	struct fence_array *array = to_fence_array(fence);
  	struct fence_array_cb *cb = (void *)(&array[1]);
  	unsigned i;
  
  	for (i = 0; i < array->num_fences; ++i) {
  		cb[i].array = array;

  		/*
  		 * As we may report that the fence is signaled before all
  		 * callbacks are complete, we need to take an additional
  		 * reference count on the array so that we do not free it too
  		 * early. The core fence handling will only hold the reference
  		 * until we signal the array as complete (but that is now
  		 * insufficient).
  		 */
  		fence_get(&array->base);

  		if (fence_add_callback(array->fences[i], &cb[i].cb,

  				       fence_array_cb_func)) {
  			fence_put(&array->base);

  			if (atomic_dec_and_test(&array->num_pending))
  				return false;

  		}

  	}
  
  	return true;
  }
  
  static bool fence_array_signaled(struct fence *fence)
  {
  	struct fence_array *array = to_fence_array(fence);

  	return atomic_read(&array->num_pending) <= 0;

  }
  
  static void fence_array_release(struct fence *fence)
  {
  	struct fence_array *array = to_fence_array(fence);
  	unsigned i;
  
  	for (i = 0; i < array->num_fences; ++i)
  		fence_put(array->fences[i]);
  
  	kfree(array->fences);
  	fence_free(fence);
  }
  
  const struct fence_ops fence_array_ops = {
  	.get_driver_name = fence_array_get_driver_name,
  	.get_timeline_name = fence_array_get_timeline_name,
  	.enable_signaling = fence_array_enable_signaling,
  	.signaled = fence_array_signaled,
  	.wait = fence_default_wait,
  	.release = fence_array_release,
  };

  EXPORT_SYMBOL(fence_array_ops);

  
  /**
   * fence_array_create - Create a custom fence array

   * @num_fences:		[in]	number of fences to add in the array
   * @fences:		[in]	array containing the fences
   * @context:		[in]	fence context to use
   * @seqno:		[in]	sequence number to use

   * @signal_on_any:	[in]	signal on any fence in the array

   *
   * Allocate a fence_array object and initialize the base fence with fence_init().
   * In case of error it returns NULL.
   *

   * The caller should allocate the fences array with num_fences size

   * and fill it with the fences it wants to add to the object. Ownership of this

   * array is taken and fence_put() is used on each fence on release.

   *
   * If @signal_on_any is true the fence array signals if any fence in the array
   * signals, otherwise it signals when all fences in the array signal.

   */
  struct fence_array *fence_array_create(int num_fences, struct fence **fences,

  				       u64 context, unsigned seqno,
  				       bool signal_on_any)

  {
  	struct fence_array *array;
  	size_t size = sizeof(*array);
  
  	/* Allocate the callback structures behind the array. */
  	size += num_fences * sizeof(struct fence_array_cb);
  	array = kzalloc(size, GFP_KERNEL);
  	if (!array)
  		return NULL;
  
  	spin_lock_init(&array->lock);
  	fence_init(&array->base, &fence_array_ops, &array->lock,
  		   context, seqno);
  
  	array->num_fences = num_fences;

  	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);

  	array->fences = fences;
  
  	return array;
  }
  EXPORT_SYMBOL(fence_array_create);