1/*
  2 * dma-fence-array: aggregate fences to be waited together
  3 *
  4 * Copyright (C) 2016 Collabora Ltd
  5 * Copyright (C) 2016 Advanced Micro Devices, Inc.
  6 * Authors:
  7 *	Gustavo Padovan <gustavo@padovan.org>
  8 *	Christian König <christian.koenig@amd.com>
  9 *
 10 * This program is free software; you can redistribute it and/or modify it
 11 * under the terms of the GNU General Public License version 2 as published by
 12 * the Free Software Foundation.
 13 *
 14 * This program is distributed in the hope that it will be useful, but WITHOUT
 15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 16 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 17 * more details.
 18 */
 19
 20#include <linux/export.h>
 21#include <linux/slab.h>
 22#include <linux/dma-fence-array.h>
 23
 24static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
 25{
 26	return "dma_fence_array";
 27}
 28
 29static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
 30{
 31	return "unbound";
 32}
 33
 34static void dma_fence_array_cb_func(struct dma_fence *f,
 35				    struct dma_fence_cb *cb)
 36{
 37	struct dma_fence_array_cb *array_cb =
 38		container_of(cb, struct dma_fence_array_cb, cb);
 39	struct dma_fence_array *array = array_cb->array;
 40
 41	if (atomic_dec_and_test(&array->num_pending))
 42		dma_fence_signal(&array->base);
 43	dma_fence_put(&array->base);
 44}
 45
 46static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
 47{
 48	struct dma_fence_array *array = to_dma_fence_array(fence);
 49	struct dma_fence_array_cb *cb = (void *)(&array[1]);
 50	unsigned i;
 51
 52	for (i = 0; i < array->num_fences; ++i) {
 53		cb[i].array = array;
 54		/*
 55		 * As we may report that the fence is signaled before all
 56		 * callbacks are complete, we need to take an additional
 57		 * reference count on the array so that we do not free it too
 58		 * early. The core fence handling will only hold the reference
 59		 * until we signal the array as complete (but that is now
 60		 * insufficient).
 61		 */
 62		dma_fence_get(&array->base);
 63		if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
 64					   dma_fence_array_cb_func)) {
 65			dma_fence_put(&array->base);
 66			if (atomic_dec_and_test(&array->num_pending))
 67				return false;
 68		}
 69	}
 70
 71	return true;
 72}
 73
 74static bool dma_fence_array_signaled(struct dma_fence *fence)
 75{
 76	struct dma_fence_array *array = to_dma_fence_array(fence);
 77
 78	return atomic_read(&array->num_pending) <= 0;
 79}
 80
 81static void dma_fence_array_release(struct dma_fence *fence)
 82{
 83	struct dma_fence_array *array = to_dma_fence_array(fence);
 84	unsigned i;
 85
 86	for (i = 0; i < array->num_fences; ++i)
 87		dma_fence_put(array->fences[i]);
 88
 89	kfree(array->fences);
 90	dma_fence_free(fence);
 91}
 92
 93const struct dma_fence_ops dma_fence_array_ops = {
 94	.get_driver_name = dma_fence_array_get_driver_name,
 95	.get_timeline_name = dma_fence_array_get_timeline_name,
 96	.enable_signaling = dma_fence_array_enable_signaling,
 97	.signaled = dma_fence_array_signaled,
 98	.wait = dma_fence_default_wait,
 99	.release = dma_fence_array_release,
100};
101EXPORT_SYMBOL(dma_fence_array_ops);
102
103/**
104 * dma_fence_array_create - Create a custom fence array
105 * @num_fences:		[in]	number of fences to add in the array
106 * @fences:		[in]	array containing the fences
107 * @context:		[in]	fence context to use
108 * @seqno:		[in]	sequence number to use
109 * @signal_on_any:	[in]	signal on any fence in the array
110 *
111 * Allocate a dma_fence_array object and initialize the base fence with
112 * dma_fence_init().
113 * In case of error it returns NULL.
114 *
115 * The caller should allocate the fences array with num_fences size
116 * and fill it with the fences it wants to add to the object. Ownership of this
117 * array is taken and dma_fence_put() is used on each fence on release.
118 *
119 * If @signal_on_any is true the fence array signals if any fence in the array
120 * signals, otherwise it signals when all fences in the array signal.
121 */
122struct dma_fence_array *dma_fence_array_create(int num_fences,
123					       struct dma_fence **fences,
124					       u64 context, unsigned seqno,
125					       bool signal_on_any)
126{
127	struct dma_fence_array *array;
128	size_t size = sizeof(*array);
129
130	/* Allocate the callback structures behind the array. */
131	size += num_fences * sizeof(struct dma_fence_array_cb);
132	array = kzalloc(size, GFP_KERNEL);
133	if (!array)
134		return NULL;
135
136	spin_lock_init(&array->lock);
137	dma_fence_init(&array->base, &dma_fence_array_ops, &array->lock,
138		       context, seqno);
139
140	array->num_fences = num_fences;
141	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
142	array->fences = fences;
143
144	return array;
145}
146EXPORT_SYMBOL(dma_fence_array_create);