1 /**
2 * Copyright (c) 2010-2012 Broadcom. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions, and the following disclaimer,
9 * without modification.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. The names of the above-listed copyright holders may not be used
14 * to endorse or promote products derived from this software without
15 * specific prior written permission.
16 *
17 * ALTERNATIVELY, this software may be distributed under the terms of the
18 * GNU General Public License ("GPL") version 2, as published by the Free
19 * Software Foundation.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
22 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
23 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
25 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
27 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
28 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
29 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include "vchiq_util.h"
35
is_pow2(int i)36 static inline int is_pow2(int i)
37 {
38 return i && !(i & (i - 1));
39 }
40
vchiu_queue_init(VCHIU_QUEUE_T * queue,int size)41 int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size)
42 {
43 WARN_ON(!is_pow2(size));
44
45 queue->size = size;
46 queue->read = 0;
47 queue->write = 0;
48 queue->initialized = 1;
49
50 _sema_init(&queue->pop, 0);
51 _sema_init(&queue->push, 0);
52
53 queue->storage = kzalloc(size * sizeof(VCHIQ_HEADER_T *), GFP_KERNEL);
54 if (queue->storage == NULL) {
55 vchiu_queue_delete(queue);
56 return 0;
57 }
58 return 1;
59 }
60
vchiu_queue_delete(VCHIU_QUEUE_T * queue)61 void vchiu_queue_delete(VCHIU_QUEUE_T *queue)
62 {
63 if (queue->storage != NULL)
64 kfree(queue->storage);
65 }
66
vchiu_queue_is_empty(VCHIU_QUEUE_T * queue)67 int vchiu_queue_is_empty(VCHIU_QUEUE_T *queue)
68 {
69 return queue->read == queue->write;
70 }
71
vchiu_queue_is_full(VCHIU_QUEUE_T * queue)72 int vchiu_queue_is_full(VCHIU_QUEUE_T *queue)
73 {
74 return queue->write == queue->read + queue->size;
75 }
76
vchiu_queue_push(VCHIU_QUEUE_T * queue,VCHIQ_HEADER_T * header)77 void vchiu_queue_push(VCHIU_QUEUE_T *queue, VCHIQ_HEADER_T *header)
78 {
79 if (!queue->initialized)
80 return;
81
82 while (queue->write == queue->read + queue->size) {
83 if (down_interruptible(&queue->pop) != 0) {
84 flush_signals(current);
85 }
86 }
87
88 /*
89 * Write to queue->storage must be visible after read from
90 * queue->read
91 */
92 smp_mb();
93
94 queue->storage[queue->write & (queue->size - 1)] = header;
95
96 /*
97 * Write to queue->storage must be visible before write to
98 * queue->write
99 */
100 smp_wmb();
101
102 queue->write++;
103
104 up(&queue->push);
105 }
106
vchiu_queue_peek(VCHIU_QUEUE_T * queue)107 VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue)
108 {
109 while (queue->write == queue->read) {
110 if (down_interruptible(&queue->push) != 0) {
111 flush_signals(current);
112 }
113 }
114
115 up(&queue->push); // We haven't removed anything from the queue.
116
117 /*
118 * Read from queue->storage must be visible after read from
119 * queue->write
120 */
121 smp_rmb();
122
123 return queue->storage[queue->read & (queue->size - 1)];
124 }
125
vchiu_queue_pop(VCHIU_QUEUE_T * queue)126 VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue)
127 {
128 VCHIQ_HEADER_T *header;
129
130 while (queue->write == queue->read) {
131 if (down_interruptible(&queue->push) != 0) {
132 flush_signals(current);
133 }
134 }
135
136 /*
137 * Read from queue->storage must be visible after read from
138 * queue->write
139 */
140 smp_rmb();
141
142 header = queue->storage[queue->read & (queue->size - 1)];
143
144 /*
145 * Read from queue->storage must be visible before write to
146 * queue->read
147 */
148 smp_mb();
149
150 queue->read++;
151
152 up(&queue->pop);
153
154 return header;
155 }
156