1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * dma-fence-array: aggregate fences to be waited together
4 *
5 * Copyright (C) 2016 Collabora Ltd
6 * Copyright (C) 2016 Advanced Micro Devices, Inc.
7 * Authors:
8 *	Gustavo Padovan <gustavo@padovan.org>
9 *	Christian König <christian.koenig@amd.com>
10 */
11
12#include <linux/export.h>
13#include <linux/slab.h>
14#include <linux/dma-fence-array.h>
15
16#define PENDING_ERROR 1
17
18static const char *dma_fence_array_get_driver_name(struct dma_fence *fence)
19{
20	return "dma_fence_array";
21}
22
23static const char *dma_fence_array_get_timeline_name(struct dma_fence *fence)
24{
25	return "unbound";
26}
27
28static void dma_fence_array_set_pending_error(struct dma_fence_array *array,
29					      int error)
30{
31	/*
32	 * Propagate the first error reported by any of our fences, but only
33	 * before we ourselves are signaled.
34	 */
35	if (error)
36		cmpxchg(&array->base.error, PENDING_ERROR, error);
37}
38
39static void dma_fence_array_clear_pending_error(struct dma_fence_array *array)
40{
41	/* Clear the error flag if not actually set. */
42	cmpxchg(&array->base.error, PENDING_ERROR, 0);
43}
44
45static void irq_dma_fence_array_work(struct irq_work *wrk)
46{
47	struct dma_fence_array *array = container_of(wrk, typeof(*array), work);
48
49	dma_fence_array_clear_pending_error(array);
50
51	dma_fence_signal(&array->base);
52	dma_fence_put(&array->base);
53}
54
55static void dma_fence_array_cb_func(struct dma_fence *f,
56				    struct dma_fence_cb *cb)
57{
58	struct dma_fence_array_cb *array_cb =
59		container_of(cb, struct dma_fence_array_cb, cb);
60	struct dma_fence_array *array = array_cb->array;
61
62	dma_fence_array_set_pending_error(array, f->error);
63
64	if (atomic_dec_and_test(&array->num_pending))
65		irq_work_queue(&array->work);
66	else
67		dma_fence_put(&array->base);
68}
69
70static bool dma_fence_array_enable_signaling(struct dma_fence *fence)
71{
72	struct dma_fence_array *array = to_dma_fence_array(fence);
73	struct dma_fence_array_cb *cb = (void *)(&array[1]);
74	unsigned i;
75
76	for (i = 0; i < array->num_fences; ++i) {
77		cb[i].array = array;
78		/*
79		 * As we may report that the fence is signaled before all
80		 * callbacks are complete, we need to take an additional
81		 * reference count on the array so that we do not free it too
82		 * early. The core fence handling will only hold the reference
83		 * until we signal the array as complete (but that is now
84		 * insufficient).
85		 */
86		dma_fence_get(&array->base);
87		if (dma_fence_add_callback(array->fences[i], &cb[i].cb,
88					   dma_fence_array_cb_func)) {
89			int error = array->fences[i]->error;
90
91			dma_fence_array_set_pending_error(array, error);
92			dma_fence_put(&array->base);
93			if (atomic_dec_and_test(&array->num_pending)) {
94				dma_fence_array_clear_pending_error(array);
95				return false;
96			}
97		}
98	}
99
100	return true;
101}
102
103static bool dma_fence_array_signaled(struct dma_fence *fence)
104{
105	struct dma_fence_array *array = to_dma_fence_array(fence);
106
107	if (atomic_read(&array->num_pending) > 0)
108		return false;
109
110	dma_fence_array_clear_pending_error(array);
111	return true;
112}
113
114static void dma_fence_array_release(struct dma_fence *fence)
115{
116	struct dma_fence_array *array = to_dma_fence_array(fence);
117	unsigned i;
118
119	for (i = 0; i < array->num_fences; ++i)
120		dma_fence_put(array->fences[i]);
121
122	kfree(array->fences);
123	dma_fence_free(fence);
124}
125
126const struct dma_fence_ops dma_fence_array_ops = {
127	.get_driver_name = dma_fence_array_get_driver_name,
128	.get_timeline_name = dma_fence_array_get_timeline_name,
129	.enable_signaling = dma_fence_array_enable_signaling,
130	.signaled = dma_fence_array_signaled,
131	.release = dma_fence_array_release,
132};
133EXPORT_SYMBOL(dma_fence_array_ops);
134
135/**
136 * dma_fence_array_create - Create a custom fence array
137 * @num_fences:		[in]	number of fences to add in the array
138 * @fences:		[in]	array containing the fences
139 * @context:		[in]	fence context to use
140 * @seqno:		[in]	sequence number to use
141 * @signal_on_any:	[in]	signal on any fence in the array
142 *
143 * Allocate a dma_fence_array object and initialize the base fence with
144 * dma_fence_init().
145 * In case of error it returns NULL.
146 *
147 * The caller should allocate the fences array with num_fences size
148 * and fill it with the fences it wants to add to the object. Ownership of this
149 * array is taken and dma_fence_put() is used on each fence on release.
150 *
151 * If @signal_on_any is true the fence array signals if any fence in the array
152 * signals, otherwise it signals when all fences in the array signal.
153 */
154struct dma_fence_array *dma_fence_array_create(int num_fences,
155					       struct dma_fence **fences,
156					       u64 context, unsigned seqno,
157					       bool signal_on_any)
158{
159	struct dma_fence_array *array;
160	size_t size = sizeof(*array);
161
162	/* Allocate the callback structures behind the array. */
163	size += num_fences * sizeof(struct dma_fence_array_cb);
164	array = kzalloc(size, GFP_KERNEL);
165	if (!array)
166		return NULL;
167
168	spin_lock_init(&array->lock);
169	dma_fence_init(&array->base, &dma_fence_array_ops, &array->lock,
170		       context, seqno);
171	init_irq_work(&array->work, irq_dma_fence_array_work);
172
173	array->num_fences = num_fences;
174	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);
175	array->fences = fences;
176
177	array->base.error = PENDING_ERROR;
178
179	return array;
180}
181EXPORT_SYMBOL(dma_fence_array_create);
182
183/**
184 * dma_fence_match_context - Check if all fences are from the given context
185 * @fence:		[in]	fence or fence array
186 * @context:		[in]	fence context to check all fences against
187 *
188 * Checks the provided fence or, for a fence array, all fences in the array
189 * against the given context. Returns false if any fence is from a different
190 * context.
191 */
192bool dma_fence_match_context(struct dma_fence *fence, u64 context)
193{
194	struct dma_fence_array *array = to_dma_fence_array(fence);
195	unsigned i;
196
197	if (!dma_fence_is_array(fence))
198		return fence->context == context;
199
200	for (i = 0; i < array->num_fences; i++) {
201		if (array->fences[i]->context != context)
202			return false;
203	}
204
205	return true;
206}
207EXPORT_SYMBOL(dma_fence_match_context);
208