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
 32static struct kmem_cache *sched_fence_slab;
 33
 34static int __init drm_sched_fence_slab_init(void)
 35{
 36	sched_fence_slab = KMEM_CACHE(drm_sched_fence, SLAB_HWCACHE_ALIGN);
 37	if (!sched_fence_slab)
 38		return -ENOMEM;
 39
 40	return 0;
 41}
 42
 43static void __exit drm_sched_fence_slab_fini(void)
 44{
 45	rcu_barrier();
 46	kmem_cache_destroy(sched_fence_slab);
 47}
 48
 49static void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
 50				       struct dma_fence *fence)
 51{
 52	/*
 53	 * smp_store_release() to ensure another thread racing us
 54	 * in drm_sched_fence_set_deadline_finished() sees the
 55	 * fence's parent set before test_bit()
 56	 */
 57	smp_store_release(&s_fence->parent, dma_fence_get(fence));
 58	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
 59		     &s_fence->finished.flags))
 60		dma_fence_set_deadline(fence, s_fence->deadline);
 61}
 62
 63void drm_sched_fence_scheduled(struct drm_sched_fence *fence,
 64			       struct dma_fence *parent)
 65{
 66	/* Set the parent before signaling the scheduled fence, such that,
 67	 * any waiter expecting the parent to be filled after the job has
 68	 * been scheduled (which is the case for drivers delegating waits
 69	 * to some firmware) doesn't have to busy wait for parent to show
 70	 * up.
 71	 */
 72	if (!IS_ERR_OR_NULL(parent))
 73		drm_sched_fence_set_parent(fence, parent);
 74
 75	dma_fence_signal(&fence->scheduled);
 76}
 77
 78void drm_sched_fence_finished(struct drm_sched_fence *fence, int result)
 79{
 80	if (result)
 81		dma_fence_set_error(&fence->finished, result);
 82	dma_fence_signal(&fence->finished);
 83}
 84
 85static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
 86{
 87	return "drm_sched";
 88}
 89
 90static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
 91{
 92	struct drm_sched_fence *fence = to_drm_sched_fence(f);
 93	return (const char *)fence->sched->name;
 94}
 95
 96static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
 97{
 98	struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
 99	struct drm_sched_fence *fence = to_drm_sched_fence(f);
100
101	if (!WARN_ON_ONCE(!fence))
102		kmem_cache_free(sched_fence_slab, fence);
103}
104
105/**
106 * drm_sched_fence_free - free up an uninitialized fence
107 *
108 * @fence: fence to free
109 *
110 * Free up the fence memory. Should only be used if drm_sched_fence_init()
111 * has not been called yet.
112 */
113void drm_sched_fence_free(struct drm_sched_fence *fence)
114{
115	/* This function should not be called if the fence has been initialized. */
116	if (!WARN_ON_ONCE(fence->sched))
117		kmem_cache_free(sched_fence_slab, fence);
118}
119
120/**
121 * drm_sched_fence_release_scheduled - callback that fence can be freed
122 *
123 * @f: fence
124 *
125 * This function is called when the reference count becomes zero.
126 * It just RCU schedules freeing up the fence.
127 */
128static void drm_sched_fence_release_scheduled(struct dma_fence *f)
129{
130	struct drm_sched_fence *fence = to_drm_sched_fence(f);
131
132	dma_fence_put(fence->parent);
133	call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
134}
135
136/**
137 * drm_sched_fence_release_finished - drop extra reference
138 *
139 * @f: fence
140 *
141 * Drop the extra reference from the scheduled fence to the base fence.
142 */
143static void drm_sched_fence_release_finished(struct dma_fence *f)
144{
145	struct drm_sched_fence *fence = to_drm_sched_fence(f);
146
147	dma_fence_put(&fence->scheduled);
148}
149
150static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
151						  ktime_t deadline)
152{
153	struct drm_sched_fence *fence = to_drm_sched_fence(f);
154	struct dma_fence *parent;
155	unsigned long flags;
156
157	spin_lock_irqsave(&fence->lock, flags);
158
159	/* If we already have an earlier deadline, keep it: */
160	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
161	    ktime_before(fence->deadline, deadline)) {
162		spin_unlock_irqrestore(&fence->lock, flags);
163		return;
164	}
165
166	fence->deadline = deadline;
167	set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
168
169	spin_unlock_irqrestore(&fence->lock, flags);
170
171	/*
172	 * smp_load_aquire() to ensure that if we are racing another
173	 * thread calling drm_sched_fence_set_parent(), that we see
174	 * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
175	 */
176	parent = smp_load_acquire(&fence->parent);
177	if (parent)
178		dma_fence_set_deadline(parent, deadline);
179}
180
181static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
182	.get_driver_name = drm_sched_fence_get_driver_name,
183	.get_timeline_name = drm_sched_fence_get_timeline_name,
184	.release = drm_sched_fence_release_scheduled,
185};
186
187static const struct dma_fence_ops drm_sched_fence_ops_finished = {
188	.get_driver_name = drm_sched_fence_get_driver_name,
189	.get_timeline_name = drm_sched_fence_get_timeline_name,
190	.release = drm_sched_fence_release_finished,
191	.set_deadline = drm_sched_fence_set_deadline_finished,
192};
193
194struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
195{
196	if (f->ops == &drm_sched_fence_ops_scheduled)
197		return container_of(f, struct drm_sched_fence, scheduled);
198
199	if (f->ops == &drm_sched_fence_ops_finished)
200		return container_of(f, struct drm_sched_fence, finished);
201
202	return NULL;
203}
204EXPORT_SYMBOL(to_drm_sched_fence);
205
206struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
207					      void *owner)
208{
209	struct drm_sched_fence *fence = NULL;
210
211	fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
212	if (fence == NULL)
213		return NULL;
214
215	fence->owner = owner;
216	spin_lock_init(&fence->lock);
217
218	return fence;
219}
220
221void drm_sched_fence_init(struct drm_sched_fence *fence,
222			  struct drm_sched_entity *entity)
223{
224	unsigned seq;
225
226	fence->sched = entity->rq->sched;
227	seq = atomic_inc_return(&entity->fence_seq);
228	dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
229		       &fence->lock, entity->fence_context, seq);
230	dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
231		       &fence->lock, entity->fence_context + 1, seq);
232}
233
234module_init(drm_sched_fence_slab_init);
235module_exit(drm_sched_fence_slab_fini);
236
237MODULE_DESCRIPTION("DRM GPU scheduler");
238MODULE_LICENSE("GPL and additional rights");