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 static struct kmem_cache *sched_fence_slab;
33 
34 static 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 
45 static void __exit drm_sched_fence_slab_fini(void)
46 {
47 	rcu_barrier();
48 	kmem_cache_destroy(sched_fence_slab);
49 }
50 
51 void drm_sched_fence_scheduled(struct drm_sched_fence *fence)
52 {
53 	int ret = dma_fence_signal(&fence->scheduled);
54 
55 	if (!ret)
56 		DMA_FENCE_TRACE(&fence->scheduled,
57 				"signaled from irq context\n");
58 	else
59 		DMA_FENCE_TRACE(&fence->scheduled,
60 				"was already signaled\n");
61 }
62 
63 void drm_sched_fence_finished(struct drm_sched_fence *fence)
64 {
65 	int ret = dma_fence_signal(&fence->finished);
66 
67 	if (!ret)
68 		DMA_FENCE_TRACE(&fence->finished,
69 				"signaled from irq context\n");
70 	else
71 		DMA_FENCE_TRACE(&fence->finished,
72 				"was already signaled\n");
73 }
74 
75 static const char *drm_sched_fence_get_driver_name(struct dma_fence *fence)
76 {
77 	return "drm_sched";
78 }
79 
80 static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
81 {
82 	struct drm_sched_fence *fence = to_drm_sched_fence(f);
83 	return (const char *)fence->sched->name;
84 }
85 
86 /**
87  * drm_sched_fence_free - free up the fence memory
88  *
89  * @rcu: RCU callback head
90  *
91  * Free up the fence memory after the RCU grace period.
92  */
93 static void drm_sched_fence_free(struct rcu_head *rcu)
94 {
95 	struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
96 	struct drm_sched_fence *fence = to_drm_sched_fence(f);
97 
98 	kmem_cache_free(sched_fence_slab, fence);
99 }
100 
101 /**
102  * drm_sched_fence_release_scheduled - callback that fence can be freed
103  *
104  * @fence: fence
105  *
106  * This function is called when the reference count becomes zero.
107  * It just RCU schedules freeing up the fence.
108  */
109 static void drm_sched_fence_release_scheduled(struct dma_fence *f)
110 {
111 	struct drm_sched_fence *fence = to_drm_sched_fence(f);
112 
113 	dma_fence_put(fence->parent);
114 	call_rcu(&fence->finished.rcu, drm_sched_fence_free);
115 }
116 
117 /**
118  * drm_sched_fence_release_finished - drop extra reference
119  *
120  * @f: fence
121  *
122  * Drop the extra reference from the scheduled fence to the base fence.
123  */
124 static void drm_sched_fence_release_finished(struct dma_fence *f)
125 {
126 	struct drm_sched_fence *fence = to_drm_sched_fence(f);
127 
128 	dma_fence_put(&fence->scheduled);
129 }
130 
131 static const struct dma_fence_ops drm_sched_fence_ops_scheduled = {
132 	.get_driver_name = drm_sched_fence_get_driver_name,
133 	.get_timeline_name = drm_sched_fence_get_timeline_name,
134 	.release = drm_sched_fence_release_scheduled,
135 };
136 
137 static const struct dma_fence_ops drm_sched_fence_ops_finished = {
138 	.get_driver_name = drm_sched_fence_get_driver_name,
139 	.get_timeline_name = drm_sched_fence_get_timeline_name,
140 	.release = drm_sched_fence_release_finished,
141 };
142 
143 struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
144 {
145 	if (f->ops == &drm_sched_fence_ops_scheduled)
146 		return container_of(f, struct drm_sched_fence, scheduled);
147 
148 	if (f->ops == &drm_sched_fence_ops_finished)
149 		return container_of(f, struct drm_sched_fence, finished);
150 
151 	return NULL;
152 }
153 EXPORT_SYMBOL(to_drm_sched_fence);
154 
155 struct drm_sched_fence *drm_sched_fence_create(struct drm_sched_entity *entity,
156 					       void *owner)
157 {
158 	struct drm_sched_fence *fence = NULL;
159 	unsigned seq;
160 
161 	fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
162 	if (fence == NULL)
163 		return NULL;
164 
165 	fence->owner = owner;
166 	fence->sched = entity->rq->sched;
167 	spin_lock_init(&fence->lock);
168 
169 	seq = atomic_inc_return(&entity->fence_seq);
170 	dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
171 		       &fence->lock, entity->fence_context, seq);
172 	dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
173 		       &fence->lock, entity->fence_context + 1, seq);
174 
175 	return fence;
176 }
177 
178 module_init(drm_sched_fence_slab_init);
179 module_exit(drm_sched_fence_slab_fini);
180 
181 MODULE_DESCRIPTION("DRM GPU scheduler");
182 MODULE_LICENSE("GPL and additional rights");
183