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_create(
 37		"drm_sched_fence", sizeof(struct drm_sched_fence), 0,
 38		SLAB_HWCACHE_ALIGN, NULL);
 39	if (!sched_fence_slab)
 40		return -ENOMEM;
 41
 42	return 0;
 43}
 44
 45static void __exit drm_sched_fence_slab_fini(void)
 46{
 47	rcu_barrier();
 48	kmem_cache_destroy(sched_fence_slab);
 49}
 50
 51static void drm_sched_fence_set_parent(struct drm_sched_fence *s_fence,
 52				       struct dma_fence *fence)
 53{
 54	/*
 55	 * smp_store_release() to ensure another thread racing us
 56	 * in drm_sched_fence_set_deadline_finished() sees the
 57	 * fence's parent set before test_bit()
 58	 */
 59	smp_store_release(&s_fence->parent, dma_fence_get(fence));
 60	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT,
 61		     &s_fence->finished.flags))
 62		dma_fence_set_deadline(fence, s_fence->deadline);
 63}
 64
 65void drm_sched_fence_scheduled(struct drm_sched_fence *fence,
 66			       struct dma_fence *parent)
 67{
 68	/* Set the parent before signaling the scheduled fence, such that,
 69	 * any waiter expecting the parent to be filled after the job has
 70	 * been scheduled (which is the case for drivers delegating waits
 71	 * to some firmware) doesn't have to busy wait for parent to show
 72	 * up.
 73	 */
 74	if (!IS_ERR_OR_NULL(parent))
 75		drm_sched_fence_set_parent(fence, parent);
 76
 77	dma_fence_signal(&fence->scheduled);
 78}
 79
 80void drm_sched_fence_finished(struct drm_sched_fence *fence, int result)
 81{
 82	if (result)
 83		dma_fence_set_error(&fence->finished, result);
 84	dma_fence_signal(&fence->finished);
 85}
 86
 87static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
 88{
 89	return "drm_sched";
 90}
 91
 92static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
 93{
 94	struct drm_sched_fence *fence = to_drm_sched_fence(f);
 95	return (const char *)fence->sched->name;
 96}
 97
 98static void drm_sched_fence_free_rcu(struct rcu_head *rcu)
 99{
100	struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
101	struct drm_sched_fence *fence = to_drm_sched_fence(f);
102
103	if (!WARN_ON_ONCE(!fence))
104		kmem_cache_free(sched_fence_slab, fence);
105}
106
107/**
108 * drm_sched_fence_free - free up an uninitialized fence
109 *
110 * @fence: fence to free
111 *
112 * Free up the fence memory. Should only be used if drm_sched_fence_init()
113 * has not been called yet.
114 */
115void drm_sched_fence_free(struct drm_sched_fence *fence)
116{
117	/* This function should not be called if the fence has been initialized. */
118	if (!WARN_ON_ONCE(fence->sched))
119		kmem_cache_free(sched_fence_slab, fence);
120}
121
122/**
123 * drm_sched_fence_release_scheduled - callback that fence can be freed
124 *
125 * @f: fence
126 *
127 * This function is called when the reference count becomes zero.
128 * It just RCU schedules freeing up the fence.
129 */
130static void drm_sched_fence_release_scheduled(struct dma_fence *f)
131{
132	struct drm_sched_fence *fence = to_drm_sched_fence(f);
133
134	dma_fence_put(fence->parent);
135	call_rcu(&fence->finished.rcu, drm_sched_fence_free_rcu);
136}
137
138/**
139 * drm_sched_fence_release_finished - drop extra reference
140 *
141 * @f: fence
142 *
143 * Drop the extra reference from the scheduled fence to the base fence.
144 */
145static void drm_sched_fence_release_finished(struct dma_fence *f)
146{
147	struct drm_sched_fence *fence = to_drm_sched_fence(f);
148
149	dma_fence_put(&fence->scheduled);
150}
151
152static void drm_sched_fence_set_deadline_finished(struct dma_fence *f,
153						  ktime_t deadline)
154{
155	struct drm_sched_fence *fence = to_drm_sched_fence(f);
156	struct dma_fence *parent;
157	unsigned long flags;
158
159	spin_lock_irqsave(&fence->lock, flags);
160
161	/* If we already have an earlier deadline, keep it: */
162	if (test_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags) &&
163	    ktime_before(fence->deadline, deadline)) {
164		spin_unlock_irqrestore(&fence->lock, flags);
165		return;
166	}
167
168	fence->deadline = deadline;
169	set_bit(DRM_SCHED_FENCE_FLAG_HAS_DEADLINE_BIT, &f->flags);
170
171	spin_unlock_irqrestore(&fence->lock, flags);
172
173	/*
174	 * smp_load_aquire() to ensure that if we are racing another
175	 * thread calling drm_sched_fence_set_parent(), that we see
176	 * the parent set before it calls test_bit(HAS_DEADLINE_BIT)
177	 */
178	parent = smp_load_acquire(&fence->parent);
179	if (parent)
180		dma_fence_set_deadline(parent, deadline);
181}
182
183static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
184	.get_driver_name = drm_sched_fence_get_driver_name,
185	.get_timeline_name = drm_sched_fence_get_timeline_name,
186	.release = drm_sched_fence_release_scheduled,
187};
188
189static const struct dma_fence_ops drm_sched_fence_ops_finished = {
190	.get_driver_name = drm_sched_fence_get_driver_name,
191	.get_timeline_name = drm_sched_fence_get_timeline_name,
192	.release = drm_sched_fence_release_finished,
193	.set_deadline = drm_sched_fence_set_deadline_finished,
194};
195
196struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
197{
198	if (f->ops == &drm_sched_fence_ops_scheduled)
199		return container_of(f, struct drm_sched_fence, scheduled);
200
201	if (f->ops == &drm_sched_fence_ops_finished)
202		return container_of(f, struct drm_sched_fence, finished);
203
204	return NULL;
205}
206EXPORT_SYMBOL(to_drm_sched_fence);
207
208struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
209					      void *owner)
210{
211	struct drm_sched_fence *fence = NULL;
212
213	fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
214	if (fence == NULL)
215		return NULL;
216
217	fence->owner = owner;
218	spin_lock_init(&fence->lock);
219
220	return fence;
221}
222
223void drm_sched_fence_init(struct drm_sched_fence *fence,
224			  struct drm_sched_entity *entity)
225{
226	unsigned seq;
227
228	fence->sched = entity->rq->sched;
229	seq = atomic_inc_return(&entity->fence_seq);
230	dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
231		       &fence->lock, entity->fence_context, seq);
232	dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
233		       &fence->lock, entity->fence_context + 1, seq);
234}
235
236module_init(drm_sched_fence_slab_init);
237module_exit(drm_sched_fence_slab_fini);
238
239MODULE_DESCRIPTION("DRM GPU scheduler");
240MODULE_LICENSE("GPL and additional rights");