1/*
2 * Copyright 2015 Advanced Micro Devices, Inc.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
21 *
22 */
23
24#include <linux/kthread.h>
25#include <linux/module.h>
26#include <linux/sched.h>
27#include <linux/slab.h>
28#include <linux/wait.h>
29
30#include <drm/gpu_scheduler.h>
31
32#include <sys/pool.h>
33
34static struct pool sched_fence_slab;
35
36int __init drm_sched_fence_slab_init(void)
37{
38#ifdef __linux__
39	sched_fence_slab = kmem_cache_create(
40		"drm_sched_fence", sizeof(struct drm_sched_fence), 0,
41		SLAB_HWCACHE_ALIGN, NULL);
42	if (!sched_fence_slab)
43		return -ENOMEM;
44#else
45	pool_init(&sched_fence_slab, sizeof(struct drm_sched_fence),
46	    CACHELINESIZE, IPL_TTY, 0, "drm_sched_fence", NULL);
47#endif
48
49	return 0;
50}
51
52void __exit drm_sched_fence_slab_fini(void)
53{
54	rcu_barrier();
55#ifdef __linux__
56	kmem_cache_destroy(sched_fence_slab);
57#else
58	pool_destroy(&sched_fence_slab);
59#endif
60}
61
62static void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
63				       struct dma_fence *fence)
64{
65	/*
66	 * smp_store_release() to ensure another thread racing us
67	 * in drm_sched_fence_set_deadline_finished() sees the
68	 * fence's parent set before test_bit()
69	 */
70	smp_store_release(&s_fence->parent, dma_fence_get(fence));
71	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
72		     &s_fence->finished.flags))
73		dma_fence_set_deadline(fence, s_fence->deadline);
74}
75
76void drm_sched_fence_scheduled(struct drm_sched_fence *fence,
77			       struct dma_fence *parent)
78{
79	/* Set the parent before signaling the scheduled fence, such that,
80	 * any waiter expecting the parent to be filled after the job has
81	 * been scheduled (which is the case for drivers delegating waits
82	 * to some firmware) doesn't have to busy wait for parent to show
83	 * up.
84	 */
85	if (!IS_ERR_OR_NULL(parent))
86		drm_sched_fence_set_parent(fence, parent);
87
88	dma_fence_signal(&fence->scheduled);
89}
90
91void drm_sched_fence_finished(struct drm_sched_fence *fence, int result)
92{
93	if (result)
94		dma_fence_set_error(&fence->finished, result);
95	dma_fence_signal(&fence->finished);
96}
97
98static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
99{
100	return "drm_sched";
101}
102
103static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
104{
105	struct drm_sched_fence *fence = to_drm_sched_fence(f);
106	return (const char *)fence->sched->name;
107}
108
109static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
110{
111	struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
112	struct drm_sched_fence *fence = to_drm_sched_fence(f);
113
114	if (!WARN_ON_ONCE(!fence)) {
115#ifdef __linux__
116		kmem_cache_free(sched_fence_slab, fence);
117#else
118		pool_put(&sched_fence_slab, fence);
119#endif
120	}
121}
122
123/**
124 * drm_sched_fence_free - free up an uninitialized fence
125 *
126 * @fence: fence to free
127 *
128 * Free up the fence memory. Should only be used if drm_sched_fence_init()
129 * has not been called yet.
130 */
131void drm_sched_fence_free(struct drm_sched_fence *fence)
132{
133	/* This function should not be called if the fence has been initialized. */
134	if (!WARN_ON_ONCE(fence->sched)) {
135#ifdef __linux__
136		kmem_cache_free(sched_fence_slab, fence);
137#else
138		pool_put(&sched_fence_slab, fence);
139#endif
140	}
141}
142
143/**
144 * drm_sched_fence_release_scheduled - callback that fence can be freed
145 *
146 * @f: fence
147 *
148 * This function is called when the reference count becomes zero.
149 * It just RCU schedules freeing up the fence.
150 */
151static void drm_sched_fence_release_scheduled(struct dma_fence *f)
152{
153	struct drm_sched_fence *fence = to_drm_sched_fence(f);
154
155	dma_fence_put(fence->parent);
156	call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
157}
158
159/**
160 * drm_sched_fence_release_finished - drop extra reference
161 *
162 * @f: fence
163 *
164 * Drop the extra reference from the scheduled fence to the base fence.
165 */
166static void drm_sched_fence_release_finished(struct dma_fence *f)
167{
168	struct drm_sched_fence *fence = to_drm_sched_fence(f);
169
170	dma_fence_put(&fence->scheduled);
171}
172
173static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
174						  ktime_t deadline)
175{
176	struct drm_sched_fence *fence = to_drm_sched_fence(f);
177	struct dma_fence *parent;
178	unsigned long flags;
179
180	spin_lock_irqsave(&fence->lock, flags);
181
182	/* If we already have an earlier deadline, keep it: */
183	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
184	    ktime_before(fence->deadline, deadline)) {
185		spin_unlock_irqrestore(&fence->lock, flags);
186		return;
187	}
188
189	fence->deadline = deadline;
190	set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
191
192	spin_unlock_irqrestore(&fence->lock, flags);
193
194	/*
195	 * smp_load_aquire() to ensure that if we are racing another
196	 * thread calling drm_sched_fence_set_parent(), that we see
197	 * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
198	 */
199	parent = smp_load_acquire(&fence->parent);
200	if (parent)
201		dma_fence_set_deadline(parent, deadline);
202}
203
204static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
205	.get_driver_name = drm_sched_fence_get_driver_name,
206	.get_timeline_name = drm_sched_fence_get_timeline_name,
207	.release = drm_sched_fence_release_scheduled,
208};
209
210static const struct dma_fence_ops drm_sched_fence_ops_finished = {
211	.get_driver_name = drm_sched_fence_get_driver_name,
212	.get_timeline_name = drm_sched_fence_get_timeline_name,
213	.release = drm_sched_fence_release_finished,
214	.set_deadline = drm_sched_fence_set_deadline_finished,
215};
216
217struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
218{
219	if (f->ops == &drm_sched_fence_ops_scheduled)
220		return container_of(f, struct drm_sched_fence, scheduled);
221
222	if (f->ops == &drm_sched_fence_ops_finished)
223		return container_of(f, struct drm_sched_fence, finished);
224
225	return NULL;
226}
227EXPORT_SYMBOL(to_drm_sched_fence);
228
229struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
230					      void *owner)
231{
232	struct drm_sched_fence *fence = NULL;
233
234#ifdef __linux__
235	fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
236#else
237	fence = pool_get(&sched_fence_slab, PR_WAITOK | PR_ZERO);
238#endif
239	if (fence == NULL)
240		return NULL;
241
242	fence->owner = owner;
243	mtx_init(&fence->lock, IPL_TTY);
244
245	return fence;
246}
247
248void drm_sched_fence_init(struct drm_sched_fence *fence,
249			  struct drm_sched_entity *entity)
250{
251	unsigned seq;
252
253	fence->sched = entity->rq->sched;
254	seq = atomic_inc_return(&entity->fence_seq);
255	dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
256		       &fence->lock, entity->fence_context, seq);
257	dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
258		       &fence->lock, entity->fence_context + 1, seq);
259}
260
261module_init(drm_sched_fence_slab_init);
262module_exit(drm_sched_fence_slab_fini);
263
264MODULE_DESCRIPTION("DRM GPU scheduler");
265MODULE_LICENSE("GPL and additional rights");
266