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 #include "vchiq_killable.h"
36
is_pow2(int i)37 static inline int is_pow2(int i)
38 {
39 return i && !(i & (i - 1));
40 }
41
vchiu_queue_init(VCHIU_QUEUE_T * queue,int size)42 int vchiu_queue_init(VCHIU_QUEUE_T *queue, int size)
43 {
44 WARN_ON(!is_pow2(size));
45
46 queue->size = size;
47 queue->read = 0;
48 queue->write = 0;
49 queue->initialized = 1;
50
51 sema_init(&queue->pop, 0);
52 sema_init(&queue->push, 0);
53
54 queue->storage = kcalloc(size, sizeof(VCHIQ_HEADER_T *), GFP_KERNEL);
55 if (!queue->storage) {
56 vchiu_queue_delete(queue);
57 return 0;
58 }
59 return 1;
60 }
61
vchiu_queue_delete(VCHIU_QUEUE_T * queue)62 void vchiu_queue_delete(VCHIU_QUEUE_T *queue)
63 {
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 * Write to queue->storage must be visible after read from
89 * queue->read
90 */
91 smp_mb();
92
93 queue->storage[queue->write & (queue->size - 1)] = header;
94
95 /*
96 * Write to queue->storage must be visible before write to
97 * queue->write
98 */
99 smp_wmb();
100
101 queue->write++;
102
103 up(&queue->push);
104 }
105
vchiu_queue_peek(VCHIU_QUEUE_T * queue)106 VCHIQ_HEADER_T *vchiu_queue_peek(VCHIU_QUEUE_T *queue)
107 {
108 while (queue->write == queue->read) {
109 if (down_interruptible(&queue->push) != 0)
110 flush_signals(current);
111 }
112
113 up(&queue->push); // We haven't removed anything from the queue.
114
115 /*
116 * Read from queue->storage must be visible after read from
117 * queue->write
118 */
119 smp_rmb();
120
121 return queue->storage[queue->read & (queue->size - 1)];
122 }
123
vchiu_queue_pop(VCHIU_QUEUE_T * queue)124 VCHIQ_HEADER_T *vchiu_queue_pop(VCHIU_QUEUE_T *queue)
125 {
126 VCHIQ_HEADER_T *header;
127
128 while (queue->write == queue->read) {
129 if (down_interruptible(&queue->push) != 0)
130 flush_signals(current);
131 }
132
133 /*
134 * Read from queue->storage must be visible after read from
135 * queue->write
136 */
137 smp_rmb();
138
139 header = queue->storage[queue->read & (queue->size - 1)];
140
141 /*
142 * Read from queue->storage must be visible before write to
143 * queue->read
144 */
145 smp_mb();
146
147 queue->read++;
148
149 up(&queue->pop);
150
151 return header;
152 }
153
