1 /* 1
2 * Copyright 2019 Advanced Micro Devices, Inc.
3 *
4 * Permission is hereby granted, free of charg
5 * copy of this software and associated docume
6 * to deal in the Software without restriction
7 * the rights to use, copy, modify, merge, pub
8 * and/or sell copies of the Software, and to
9 * Software is furnished to do so, subject to
10 *
11 * The above copyright notice and this permiss
12 * all copies or substantial portions of the S
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT W
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE W
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINF
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIA
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CO
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH
20 * OTHER DEALINGS IN THE SOFTWARE.
21 *
22 */
23 #include <linux/semaphore.h>
24 #include <linux/atomic.h>
25
26 /*
27 * Reusable 2 PHASE task barrier (rendez-vous
28 * Based on the Little book of semaphores - ht
29 */
30
31
32
33 #ifndef DRM_TASK_BARRIER_H_
34 #define DRM_TASK_BARRIER_H_
35
36 /*
37 * Represents an instance of a task barrier.
38 */
39 struct task_barrier {
40 unsigned int n;
41 atomic_t count;
42 struct semaphore enter_turnstile;
43 struct semaphore exit_turnstile;
44 };
45
46 static inline void task_barrier_signal_turnsti
47
48 {
49 int i;
50
51 for (i = 0 ; i < n; i++)
52 up(turnstile);
53 }
54
55 static inline void task_barrier_init(struct ta
56 {
57 tb->n = 0;
58 atomic_set(&tb->count, 0);
59 sema_init(&tb->enter_turnstile, 0);
60 sema_init(&tb->exit_turnstile, 0);
61 }
62
63 static inline void task_barrier_add_task(struc
64 {
65 tb->n++;
66 }
67
68 static inline void task_barrier_rem_task(struc
69 {
70 tb->n--;
71 }
72
73 /*
74 * Lines up all the threads BEFORE the critica
75 *
76 * When all thread passed this code the entry
77 */
78 static inline void task_barrier_enter(struct t
79 {
80 if (atomic_inc_return(&tb->count) == t
81 task_barrier_signal_turnstile(
82
83 down(&tb->enter_turnstile);
84 }
85
86 /*
87 * Lines up all the threads AFTER the critical
88 *
89 * This function is used to avoid any one thre
90 * used repeatedly .
91 */
92 static inline void task_barrier_exit(struct ta
93 {
94 if (atomic_dec_return(&tb->count) == 0
95 task_barrier_signal_turnstile(
96
97 down(&tb->exit_turnstile);
98 }
99
100 /* Convinieince function when nothing to be do
101 static inline void task_barrier_full(struct ta
102 {
103 task_barrier_enter(tb);
104 task_barrier_exit(tb);
105 }
106
107 #endif
108
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